THE UNIONINAE (MOLLUSCA, PELECYPODA, NAIADACEA)

OF FISHERY BAY, SOUTH BASS ISLAND, LAKE ERIE

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

By

DAVID HONOR STANSBEKY, B.S., M.S.

The Ohio State University I960

Approved by

Adviser & Department of Zoology and Entomology ACKNOWLEDGMENTS

This study was nade under the supervision of Dr* Thomas H*

Langlois to whom I owe a debt of gratitude for numerous suggestions and constructive criticisms. I have also been fortunate in having the use of the extensive library and collections of the Division of

Mollusks of the University of Michigan Museum of Zoology and I wish to thank Dr* Henry van der Schalie for this privilege and many others received during the course of this study. I greatly appre­ ciate the valuable suggestions given by Dr. Aurele LaRocque, Dr*

Ralph Dexter, Dr. H* Ray Eggleston, and Mr. Clarence Clark, each of whom gave freely of his time and knowledge.

The arduous task of collecting was made less difficult by the assistance of Mr. Paul Webster, master of the Stone Laboratory research vessel BIOLAB, and Mr. Ernest Miller, Superintendent of the

Ohio State Fish Hatchery at Put-In-Bay, Ohio*

To these and to others who contributed in one way or another to the fund of information upon which this study is based I wish to express ay sincere appreciation.

ii TABLE OF CONTENTS

Pag®

INTRODUCTION...... 1

A HISTORY OF THE STUDY OF THE NAIADES OFLAKE HI IE...... 6

'EE ECOLOGICAL, ZOOGEOGRAHIICAL,TAXONOMIC IEOBLSM ...... 12

METHODS AND MATERIALS...... 20

FhyBiography...... 20 Collection of Specimens...... 21 Collection of Data from Specimens...... 23 Treatment of Data...... 33 Growth end Longevity...... 39

THE mYSIOGRflJHY OF FISHERY BAY...... 53

General Characteristics...... 53 Tervilligar1s Pond...... 61 Inner Bay...... 66 Outer Bay...... 70

THE ORIGIN OF 3HE LAKE ERIE NAIAD FAUNA...... 72

SUPERFAMILY NAIADACEA MENKE...... 84

Fusconaia flava flava...... 86 Fusconala flava undata ...... 90 Amhlema plicata pllcata...... 108 Amblema pllcata peruviana...... 11^ Quadrula ouadrula quadrula ...... 1 3 3 Quadrula pustulosa...... 1^8 Cyclonaias tuberculata...... 160 Pleurohema cordatum coccineum...... 170 Elllptlo dllatatus...... 18^

SUMMARY...... 198

LITERATURE CITED...... 200

AUTOBIOGRAIHY...... 216

ill LIST OF TABLES

TABLE Page

1 Interpretation of Terms Used by Naiadologists in Descriptive Studies...... 26

2 Age and Growth Data of Lake Erie Naiades...... UU

3 Age and Growth Data of Lake Erie Naiades...... U5

1; Age and Growth Data of Naiades...... U6

5 Age and Growth Data of Naiades...... U7

6 Age and Growth Data of Lake Erie Naiades...... i+8

8 Age and Growth Data of Lake Erie Naiades......

9 Age and Growth Data of Lake Erie Naiades...... 52

10 Summary of Dimensional and Proportional Data of Shell Morphology of Fusconaia Flava...... 96

11 Dimensional and Proportional Data of Fusconaia Flava Related to Length Group...... 96

12 Age-Length Relationship of Fusconaia Flava...... 99

13 Summary of Dimensional and Proportional Data of Shell Morphology of Amblema Plicata...... 120

lU Dimensional and Proportional Data of Amblema Plicata Related to Length Group...... 120

15 Age-Length Relationship of Amblema Plicata...... 125

16 Age-Length Relationship of Amblema Plicata (Say). . . 126

17 Summary of Dimensional and Proportional Data of Quadrula Quadrula Quadrula (Rafinesque)...... 139

iv LIST OF TABLES (contd.)

TABLE Page

18 Dimensional and Proportional Data of Quadrula Quadrula (Rafinesque) Related to Length Group. . . 139

19 Age-Length Relationship of Quadrula Quadrula (Rafinesque)...... Iii3

20 Summary of Dimensional and Proportional Data of Shell Morphology of Quadrula Pustulosa (Lea)...... 155

21 Dimensional and Proportional Data of Quadrula Pustulosa (Lea) Related to Length Group...... 155

22 Age-

23 Summary of Dimensional and Proportional Data of Shell Morphology of Cyclonaias Tuberculata (Rafinesque)...... 16U

2U Age-Length Relationship of Cyclonaias Tuberculata . . 167

25 Summary of Dimensional and Proportional Data of Shell Morphology of Pleurobema Cordatum Coccineum (Conrad)...... 177

26 Dimensional and Proportional Data of Pleurobema Cordatum Coccineum (Conrad) Related to Length Group...... 177

27 Age-Length Relationship of Pleurobema Cordatum Coccineum...... 180

28 Summary of Dimensional and Proportional Data of Shell Morphology of Elliptio Dilatatus (Rafinesque)...... 191

29 Dimensional and Proportional Data of Elliptio Pilatatus (Rafinesque) Related to Length Group . . 191

30 Age-Length Relationship of Elliptio Dilatatus. . . . 195

v LIST OF FIGURES

FIGURE Page

1 Fishery Bay from the air (Langlois)...... 56

2 Fishery Bay from the north (Langlois)...... 56

3 Alligator Bar— normal water level (Langlois) ...... 57

it Alligator Bar— emerged during seiche (Langlois). . . . 57

5 Causeway cut during seiche (Langlois)...... 58

6 Alligator Bar emerged during seiche (Langlois) .... 58

7 Terwillegar’s Pond— normal water level (Langlois). . . 62

8 Terwillegar’s Pond during seiche (Langlois) ...... 62

9 Fusconaia flava flava (Rafinesque, 1820) dorsal view . 87

10 Fusconaia flava flava (Rafinesque, 1820), lateral view...... 8 7

11 Fusconaia flava flava (Rafinesque, 1820), interior view...... 87

12 Pleurobema cordatum coccineum (Conrad, 1836), dorsal view ...... 87

13 Pleurobema cordatum coccineum (Conrad, 1836), lateral view...... 87

lit Pleurobema cordatum coccineum (Conrad, 1836), dorsal view...... 87

15 Forms of Fusconaia flava...... 91

16 Amblema plicata (Say, 1817) lateral view ...... 109

17 Elliptio dilatatus (Rafinesque, 1820) lateral view . . 109

vi LIST OF FIGURES (CONTD.)

FIGURE Page

18 Forms of Amblema plicata...... 115

19 Quadrula quadrula quadrula (Rafinesque, 1820), dorsal view...... 135

20 Quadrula quadrula quadrula (Rafinesque, 1820), lateral view...... 135

21 Quadrula quadrula quadrula (Rafinesque, 1820), interior view...... 135

22 Quadrula pustulosa (Lea, 1831), lateral view...... 151

23 Cyclonaias tuberculata (Rafinesque, 1820), lateral view...... 151

vii GRAPHS

GRAPH Page

I Age-Length Relationship of Fusconaia flava...... 100

II Age-Length Relationship of Amblema Plicata...... 128

III Age-Length Relationship of Quadrula quadrula quadrula...... lUi

IV Age-Length Relationship of Quadrula pustulosa .... lkk

V Age-Length Relationship of Cyclonaias tuberculata . . 168

VI Age-Length Relationship of Pleurobema cordatum coccineum...... 181

VII Age-Length Relationship of Elliptio dilatatus .... 196

viii MAPS

Lake Erie and Its Tributary Streams...... 3

The Bass Islands of Lake Erie, Put-in-Bay Twp., Ottawa Co., Ohio* * ...... —V).

Fishery Bay of Lake Erie South Bass Island, Put-in-Bay Township, Ottawa County, Ohio. . . . 5

The Bay Areas of South Bass Island, Put-in-Bay Twp., Ottawa Co., Ohio...... 55

Fishery Bay of Lake Erie ...... 59

Fishery Bay of Lake Erie, Put-in-Bay Twp., Ottawa Co., Ohio...... 60

Terwillegar's Pond of Fishery Bay, Put-in-Bay Twp., Ottawa Co., Ohio...... 63

Lake Maumee, High Stage...... 78

The Cary-Port Huron, or Two Creek, or Lake Wayne Stage...... 78

Kirkfield Stage of Huron and Michigan Basins Early Erie Stage...... 81

Distribution of Naiad Faunal Groups in the Northeastern United States...... 81

Distribution Records of Fusconaia f. flava, Fusconaia flava undata, and Pleurobema cordatum coccineum in Fishery Bay...... 97

Distribution of Amblema p. plicata and Amblema plicata peruviana in Fishery Bay......

ix MAPS (contd.)

MAP Page

XIV Distribution Records of Quadrula cj. quadrula and quadrula pustulosa in Fishery Bay...... II4.I

XV Distribution Records of Elliptio dilatatus and Cyclonaias tuberculata in Fishery B a y ...... 193

x INTRODUCTION

This study of the naiad fauna of Fishery Bay at South Bass

Island in the western basin of Lake Erie was initiated in the fall of 1953 as one phase of a comprehensive study of the entire bay area. The present report deals with the Unioninae of Fishery Bay*

Collections and observations of the major fauna1 and floral groups represented were made during the following two years in each habitat area within the bay as well as in several other bays and the open lake in the surrounding region. Subsequent collections of naiades were made in the fall of 1956 and again in the summer of

1957, but most of the material upon which this report is based was obtained during the two-year period beginning in the fall of 1953*

Since 1955 the collection itself has been enriched by the addition of many specimens from numerous localities other than Fishery Bay*

The largest accession (1953) was that of the K* G. Wood Collection from the western basis of Lake Erie* These specimens from the lake, along with other collections, many from central Ohio streams, have been valuable a3 reference material with which to compare the bay forms.

The objectives of this study are to determine (1) what species of naiades inhabit the bay, (2) in which of the bay habitats the various species live, (3) the variability of each species within a single habitat area and, in cases of greater distribution, from one 2 habitat area to another, (U) the growth rate and longevity of each species in the study area, (5) some of the conditions (physical, chemical, and biological) tinder which this fauna lives, and (6) the probable origin of the various species which at present comprise the naiad population of the bay.

All the species collected, regardless of the number of specimens taken, are included in this study. It is believed that the knowledge gained from a few specimens carefully studied is far better than the only alternative of no knowledge at all. LAKE

HURON

ONT.

LAKE

ONTARIO

LAKE ERIE

OHIO I 23456789 10 100 MILES

MAP I. L A O IRIE AND ITS TRIBUTARY STREAMS I----- 1 I i The Island Region of western Lake Erie i

VJ N

M o u t h B a s s I s l a n d

^S-^Su&A* IstAND

M w d l h B a s s Isl a ho

x£ > Ba l l a s t I s l a n d

G/a n a l TAN J jjl ahO

So u t h B a s s I s l a n d

£ ^ > Q aajshh I s l a n d THE BASS ISLAMDS OF IA ME ERIE, PUT-/M- B A / TWP.) O T T A W A CO., MAP II. 9 Staavs OH/O Is l a n d O + 5 M tt.e s LAKE ERIE

HUNDRED FEET Peach Point

FISHERY BAY

GIBRALTAR ISLAND

SOUTH BASS ISLAND Oak Point

MAP III. FISHERY BAY OF LAKE ERIE, SOUTH BASS ISLAND, PUT-IN-BAY TOWNSHIP, OTTAWA COUNTY, CHIO A HISTORY OF THE STUDY OF THE NAIADES OF LAKE ERIE

The naiad fauna of the Mississippi Basin (Van der Schalie,

19*>0: kSl) of North America has been of interest to students of conchology and malacology since its discovery in the early eighteen hundreds. In examining the early literature in this field one finds such names as Say, Lamarck, Rafinesque, DeKay, and Kirtland, familiar in many fields of zoology as well as Lea, Barnes, Conrad, Hildreth, and Swainson, best known perhaps to students of the mollusks. These men were primarily concerned with seeking out and describing the many "new species" of missels which inhabited the vast drainage basin west of the Appalachians. Their zeal in this undertaking led them

(as it did others in other fields) to describe as species many of the ecological variants and aberrant forms which came their way. In those species exhibiting sexual dimorphism, the male and female were frequently described as two distinct species (Kirtland, l83Utll7)«

These practices led to considerable confusion in the taxonomic nomen­ clature of the group. Although this problem has been solved in most instances by relegating to synonony those names which proved to be redescriptions, there yet remains the problem of properly treating morphological-geographical and morphological-ecological clines.

These difficulties could hardly have been foreseen by early workers especially in view of their "type" concept of the species. In view 7

of the complexity and the extent of the fauna as we know it today,

it is to their credit that they accomplished the truly remarkable

job they did. Their work has also made the modern student of the

naiades acutely aware of the nature and degree (if not the explana­

tion) of the variations that exist In this complex group.

The first published record of naiades in Lake Erie is

apparently that of the original descriptions of Unio alatus and Unio

pllcatus by Thomas Say (1817). An interesting problem of authorship

arose here because the type specimens were collected in Lake Erie by

Lesueur and given to Say, along with the suggested trivial name

pllcatus for the non-alate individual (Simpson, 1900:767)* Say

figured the specimen in the article on conchology in Nicholson's

Encyclopedia (of Arts and Sciences) (1817) as a variety of Unio

crassus (lea, 1870:30). Barnes later (1823:120) recognized the

variety as a species, gave it a verbal description and listed

Lesueur as author— as had Say. This is, as far as I can learn, the

only instance where the type of a species was collected and named by

one individual, figured by a second, verbally described by a third,

and published by a fourth. Since Say's figure constitutes a valid description he is today credited with the authorship. The fact

that Barnes had actually redescribed a different form (U. peruviana

Lam.) under the name of U. plicatus Lesueur led to even further

confusion which persisted until untangled hyUtterback (1916:116)

and Qrtaann (1919:27) nearly a century later. Lipumia nasuta, another common species in Lake Erie, was also described by Say in this same 8 publication, although the type locality was given as the Delaware and

Schuylkill Rivers.

Lamarck (1819»7L, 532) described U. rectus, U. clavus, and a

"variety of U. crassidens" from Lake Erie. The following year

Rafinesque (1820) described 68 species of naiades from the Ohio

River and/or its tributaries. Eleven of these species were eventually recorded from Lake Erie. Although several additional forms have been described from Lake Erie since the time of Say and Lamarck, only the species mentioned above, i.e., Amblema plicata (Say), Proptera alata

(Say), Ligumia recta (Lamarck), and Pleurobema clave: (Lamarck), have been established as valid species. The other forms, to be reviewed in the following account of the species, have been recognized as questionable subspecies or ecological variants of previously described forms

(Van der Schalie, 19Ul:2l|6). It is interesting to note that P. clava is known from Lake Erie only from its original description. This fact suggests an error in the type locality and its correctness has been rightly questioned by La Rocque (1953:97)* There remains, how­ ever, in view of evidence to be presented below the possibility that this, as well as several other questioned records (Goodrich and

Van der Schalie, 1932:12), may well be correct.

The naiad literature of the middle and late nineteenth century was primarily descriptive (Lea, 1828, 1829, 1831* 183b* etc., to 187U) (Conrad, 183U, 1836, 18U1, 18U2, etc., to 1868) (Say, 1817,

1818, 1829* etc.* to 183U) (Rafinesque, 1818, 1819* 1820* 1831* 1832)

(Barnes* 1823, 1828) (Swainson, 1822, 1820-1833* 1835* 18U0) (Green, 9

1827, 1830, 1832) (Lamarck, 1791-1832, 1799, 1801, l8o£, etc., to

1830) with a generous sprinkling of locality lists (DeKay, 18U3)

(Dewey, 1856) (Hubbard, 18 ) (Whiteaves, 1861) (Lewis, 187U)

(Valton, 1891) (Snith, 189U) and personal collection check lists

(Ravenel, I83U) (Jay, 1852).

These were followed, near the turn of the century, by

several attempts to deal with the origin and distribution of the many

forms described. Some of the earliest contributions to these prob­

lems in the Lake Erie area are those of Ball (I86lsli5-U6) and

Whiteaves (1861). Ball recorded the discovery of several species of

fossil or subfossil "uniones" from what he interpreted to be an ancient Niagara River bed at Niagara Falls, Ontario. Whiteaves dealt with the more general topic of the biogeography of lower

Canada. Walker (1889) reported the discovery of the Atlantic Drain­ age naiad Elliptic ccmplanatus (Dillwyn, 1817) in Michigan and later

(1891) specifically noted its occurrence In northern Michigan.

This instance of discontinuous distribution, coupled with that which existed in the Grand River of Lake Michigan, when added to Walker's interest in historical geology, may well have been the prdblem- challenge combination which was responsible for Walker's later con­ tributions along this line. In his paper on the molluscan fauna of

Michigan (Walker, 1891;: 13) he observed that the Lake Michigan tributaries had species which "belong mostly to the Strepomatidae and

Unionidae, the characteristic families of the Mississippi Valley fauna" and notes that "If this is found to be true, it would be in 10 accord with the theory of the geologists, that, toward the end of the glacial period the great lakes had their outlet to the south into the

Mississippi Valley, and tend to show that during that period these forms made their way north into Lake Michigan, and thence into its tributaries. . •" While there is no evidence (other than the sug­ gestion above) of knowledge of the Wabash-Maumee connection in this paper, Walker later (1898:12) includes the Des Plaines-Illinois and the Saginaw-Grand outlets in addition to the Maumee-Wabash route in explaining the origin of the Michigan naiades. The postglacial migration routes from the east, the Trent and Nipissing Outlets, are later dealt with in conjunction with a consideration of the faunal history of the naiades of the entire Great Lakes Basin as it exists today (Walker, 1913)*

Ortmann (1912, 1913, 1919, 192U) succeeded Walker as the principal North American student of naiad zoogeography, and it is chiefly through his studies (1921;: 113) that the post-glacial valley of the Lake Erie Basin suggested by Walker (1913:16) was verified*

Van der Schalie (1938:10) demonstrated that the discontinuous distri­ bution of particular elements of the naiad fauna of the Clinton,

Rouge, Huron, Raisen and Maumee Rivers of Lake Erie also reflected its origin in the manner postulated by Walker and Ortmann.

In addition to taxonomic and zoogeographic works,some of which are listed above, the Lake Erie naiades have more recently been utilized in studies of nacreous and epidermal variation (Grier, 1920), morphological variation (Grier, 1920), erosion and thickness (Grier, 11

1920), sexual dimorphism (Grier, 1920), and growth rate (Grier,

1922). Wood (1953) made a study of the habitat distribution of the benthic invertebrates of the western basin of Lake Erie including the naiades in his work* It was found that the bivalves made tp

78*3 per cent (by weight) of the benthic fauna--even with the weight of the shells deducted. The results of these studies are referred to in appropriate places in the following text*

The only previous study known which refers specifically to the naiad fauna of Fishery Gay is that of Brown, Clark, and Gleissner

(1938)* These workers found that the Fishery Bay naiades were larger at any given age than Pelee Island specimens of the same species but were smaller than corresponding forms collected at East Harbor on the mainland shore. This fact was correlated with the degree of exposure of these habitats to wave action, the degree of stunting being directly related to the amount of exposure. The thoroughness of their sampling is reflected in the fact that they collected 21* of the 27 species now known to inhabit the bay. Of the three species herein added to the list, two are apparently restricted to the pond (not sampled in their study) and the third is represented in the collection by only three Fishery Bay specimens. THE ECOLOGICAL, ZOOGEOGRAPHICAL, TAXONOMIC PROBLEM

The naiad fauna of Lake Erie is unusual in several ways* Most,

if not all, of the species found there are markedly smaller than their

counterparts found in the streams tributary to the lake* This so-

called dwarfed, stunted or depauperate fauna is so striking that the

majority of the species recorded from the lake have, at one time or

another, been described as species or subspecies distinct from those

which inhabit streams (Lea, 18U0, 1857, 1862) (Conrad, 183U) (Slopson,

1900) (Grier, 1918) (Baker, 1922, 1927, 1928). In view of the paucity

of information concerning variation and distribution available to

workers such as Lea, Conrad, and Simpson, it is apparent that they were simply describing newly discovered forms as new taxonomic

entities.

As the geographic distribution of the naiades became better

known it was found that most lake habitats produced stunted forms while most streams did not. It became obvious that these lake forms today have a discontinuous distribution. The possibility that all

lakes (and ponds) having such a fauna were once interconnected in a manner permitting migration seems highly unlikely. While the evidence

just cited is highly speculative, that obtained by Brown et al. (1938) was not. These workers found that the degree of stunting within the lake was predictable and varied with habitat. This evidence strongly

12 13

indicates, and Van der Schalie (19U1), along with most other con­

temporary students, concludes that naiad lake forms are ecoforms and

should not be recognized as subspecies* He suggests:

If for any reason whatsoever one wishes to designate a form it would be more sensible to do so as follows: Lanpsilis siliquoidea form rosacea. A rule of this sort wbul

I would add only one modification to the above suggestion and that is to use the term ecoform preceeding the trinomen if it has been established that the form is due principally to the action of the environment on the individual. In this manner the term "form" could still be used in the general sense of na group having a dif­ ferent structure," be it due primarily to environment or heredity*

Baker, Grier, and others apparently were aware of the eco­ logical nature of these lake-dwelling naiades but nevertheless were of the opinion that they should be designated by a trinomial. Baker

(1928:1<0) states:

In the matter of varietal names, the writer believes that any form which can be distinguished from another should bear a name. Names are but handles to use in descriptive work and the trinomial system lends itself clearly to the designation of varieties. These varieties may be geographical or ecological*

Ortmann (1919:81) was more conservative in his use of tri­ nomials and, while using the names supplied by others, did not, at least as fhr as Lake Erie is concerned, coin any new names himself*

This was fortunate in view of the fact that Ortmann was familiar with Ill

the lake fauna and could easily have followed the precedent of Baker

and Grier thus burdening the synonomy with many more names.

Most of the evidence supports the generally accepted infer­

ence that the Lake Erie naiades are ecoforms of species also found

in the streams and, as such, should not be accorded either specific

or subspecific status. The problem then becomes one of determining

to which stream species these lake ecoforms should be assigned. It

has seemed natural to associate each with its most closely related

form living in the adjacent lake tributaries. Fusconaia flava

parvula (Grier, 1918) of the lake thus became the ecoform of Fusconaia

flava (Raf., 1820) of the tributaries and Pleurobema cordatum pauper-

culum (Sin?)son, 1900) became the ecoform of Pleurobema cordatum coc­

cineum (Conrad, 1836), a stream subspecies also found in the lake

tributaries. This policy has been generally followed by vorkerw in

this field for the past twenty years.

There is found among stream forms a problem of variability

similar to that of the lake forms. The term similar is important

here because, although the problem involves variability usually

related to habitat and deals with many of the same species or species

complexes which are present in Lake Erie, the degree of variability

occurring within a drainage basin such as the Ohio River is markedly

greater than that observed in the same form in the lake. While the

dwarfed forms in Lake Erie seemed to constitute a single taxonomic unit (for each species represented) within the lake environs, the

stream forms were described under as many as five different names. In 15 most cases each described entity was definable and distinguishable from the others and inhabited streams of a particular size. The accumulation of additional specimens during the first quarter of the present century revealed that species within each complex were, or seemed to be, connected by a series of intermediate forms. In passing from a headwaters tributary down to thelcwer Ohio or Mississippi River one might witness an apparent gradual transition from one species to another. This clinal distribution is particularly striking in, but not limited to, the Subfamily Unionise (Ortmann, 1920:311) and is represented here by the following complexes:

Fusconaia flava Complex

Headwaters form flava Rafinesque, 1820. Compresse3, Elongate, form rubfgtnosa Lea, 1829. Low unbones, Non-sulcate form trigona Lea, 1831*

Large River Obese, Short, form undata Barnes, 1823* High unbones, $ Sulcate form wagneri Baker, 1928.

Pleurobema cordatum Complex

Headwaters form coccineum Conrad, 1836* Compr essed, Elongate, Low uSbones, form cordatum Rafinesque, 1820, Non-sulcate

i \ form catillus Conrad, 1836*

t 16

* Large River \ jese, form plenum Lea, 181*0. Short, High umbones, t form pyramidatum Lea, 183U. Sulcate

Amblema p H cat a Complex

Headwaters form costata Rafinesque, 1820* Compressed, Fluted wing, Low umbones 1 form rariplicata Lamarck, 1819* 1 Large River Obese, Non-fluted wing 1 form peruviana Lamarck, 1819* High umbones

There are a number of other complexes such as the Laapsilis

ovata Complex and the Dysnomia perplexa Complex, both in the Lamps!linae.

Several of the forms listed above have long been relegated to the syn-

cnomy of other members of their species complex. They are used here because measurements given in the original descriptions or taken from

the original plates establish them as intermediates between recognized

forms. It should be kept in mind that each complex represents a series

of anatomically different forms, each of which is related to a some­ what different habitat, and is more or less connected by intermediates.

The problem of variation of stream dwelling members, of species com­ plexes is treated here because it has a direct bearing upon the

identity of several of the naiades of Lake Erie. 17

There are at least three possible explanations of the observed facts concerning the relationships between the apparently intergrading members of each of the several systematic complexes* They are:

(1) Each form within a complex may be genetically essentially the same as the others and none reproductively isolated from the others. If this be true, the obvious differences in anatomy would be a result of the effects of the different environments. In this case we might expect as many different forms as there are different environments which influence growth form. The result would be a highly variable (polymorphic) species. The variability of the species would, within the limits set by genetic composition, be determined by the range of environments in which it lives and the extent to which these environments affect the growth form.

(2) Each form within a complex may be reproductively isolated from the other forms. These several forms then constitute sibling species (Mayr et al., 191:2). If this were the case, it is apparent that the varieties of each such 3pecies would overlap those of at least one of the others. This would render the identification of some intermediate individuals an extremely difficult and perhaps, at times, inpossible task. The inpossibility of the identification of these sibling species would not, however, alter the fact of their existence. In the absence of morphological, physiological or other intrinsic differences between forms it would seem that tests of re­ productive isolation alone would verify or disprove this theory* 18

(3) Each form within a complex may be only partially isolated

(reproductively) from the others. The differences between these

forms would then be attributable in part to a difference in genetic

composition and in part to environmental differences. Cases of

several defined forms having few intermediates may represent nearly

isolated groups (gene pools) between which the gene exchange has all but ceased. Such populations have been termed sympatric subspecies*

although this expression has lost favor in recent years. At least

one well known systematist (Mayr et al.* 1953:37) maintains that

such a situation is impossible.

In the absence of any direct means of measuring the degree of reproductive isolation that may exist between naiad populations or population segments in nature* the evidence needed to determine the relationship of these forms must be sought elsewhere.

While the nineteenth century strident of the naiades had only morphology to guide him in learning the ielitionshlps of the forms with which he dealt* the modern student is somewhat more fortunate— not only in having a much better knowledge of the variability of these faunal elements but* more especially* of the distribution patterns of these variaties. A knowledge of the type and degree of variation and geographic distribution* viewed in the light of our understanding of population genetics* gives us a much clearer insight into evolution on the species and subspecies levels. This is precisely the knowledge and understanding required to deal with taxonomy in a realistic nanner and to avoid decisions based on hunch* 19 guess, and subjective vhim vhich have given the science of classifi­ cation a bad name in some quarters in the past. While it is not assumed that a knowledge of these things will solve all systematic problems, it seems that little real progress can be made without them. METHODS AND MATERIALS

Physiography

The map of the bay area was constructed from data obtained by

triangulation with a surveyor's transit. Depth contours of the pond

and inner bay were made from soundings taken through the ice using

either a graduated lead pine or an oak sounding rod. Depths in the

outer bay are based upon those taken by the U. S. Lake Survey (1936)

modified to compensate for the increase in lake level (2.10 ft.)

which occurred during the twenty year period between 1936 and 1956

(james L. Verber, personal communication). The docks and seawalls

were measured with a surveyor's tape and points determined by tri­

angulation were checked by tape where possible. A grid of squares one

hundred feet on a side was then superimposed over the finished chart,

thus permitting the fixing of any collection site (using coordinates)

to the area encompassed by each square. This technique proved satis­

factory except In places where habitats changed sharply. In these

situations a note concerning the habitat in addition to the appro­ priate coordinates proved adequate. The sediment terminology used

here is essentially that of Wentworth's Classification (Welch, 19U8:

353) with sediment sizes grouped as indicated by the brackets below.

2 0 2 1

Particle Diameter Group (millimeters) Particle Name Name

256 Boulder Rocks 65 - 255 Cobble h -6k Pebble Gravel 2.0 - 3.9 Granule * 1.0 - 1.9 Very coarse sand 0.5 - 0.9 Coarse sand 0.25 - 0.U9 Medium sand ^ Sand 0.125 - 0.2U9 Pine sand 0.062 - 0.12U Very fine sand 0.00U - 0.061 Silt Silt 0.000 - 0.0039 Clay Clay

The expression "rubble'' is here used to refer to an ill-sorted mixture of coarse gravel and rocks, either angular and/or water worn.

Collection of Specimens

Attempts to collect naiades were made by every means that seemed likely to prove fruitful. Efforts at quantitative sampling using an Ekman Dredge were abandoned after several days' labor pro­ duced only two specimens. The "noodllng"or "pollivogging" technique of passing the fingers lightly over the bottom in waters up to neck deep was also unproductive. This method is many times very successful in streams where the water is so turbid with plankton or silt that the bottom cannot be seen. Dredging, a successful procedure if an otter trawl is used in the deep lake muck, was only moderately suc­ cessful when smaller, two to four foot (width) dredges were used in the bay. This, however, was the oily way, except hy diving, that depths over ten feet could be sampled and, even then, the rocky bottoms at those depths were all but impossible to work. Skin diving 2 2 in boulder strewn areas, following dredging, established the inef­ ficiency of the operation of dredges over such a bottom— a large number of specimens were taken where the dredge had taken few or none at all. A shovel and floating sieve arrangement produced a few juveniles in shallow areas but worked no better than a dredge and required considerable more labor. The water was seldom clear enough for diving, but this seemed to be the only feasible method of taking specimens from the deeper rocky bottoms. Pull advantage was taken of each of several rare periods of warm clear water. The best col­ lecting was accomplished during and just following prolonged strong blows from the southwest. The net effect of such a blow is a surge of water to the east lowering the water level in the island region as much as seven feet (Langlois, 1952:6). Such a phenomenon is known as a seiche. The naiades may then be hand picked from exposed sub­ strates that are usually three to five feet under water. The only disadvantage is that these blows usually came in late November or

March when the water temperature is below 7°C. (U5°F.) and most of the mussels are M ug in" beneath the sand and gravel and difficult to see* Barnes (l823:llU) also noted this winter burying behavior and subsequent exposure above bottom in summer. An unusual opportunity came on September 21, 195U, when a wind generated seiche of the type described lowered the water level at least five feet for a period of several hours. The naiades were for the most part in their summer positions, protruding above the bottom or actively moving about. Six hundred sixty naiades, the largest single collection made in the 23

entire course of the study, were taken in approximately four

hours*

Collection of Data from Specimens

All specimens collected were taken alive to the laboratory

where individuals over ten grams were weighed to the nearest gram on

a Hanson Dietetic Scale. This scale has a capacity of $00 grams

and is calibrated in one gram graduations. The smaller specimens were

weighed to the nearest tenth of a gram using an Chaus beam balance

having a scale calibrated from zero to ten grams, in one-tenth gram

steps. Care was taken to remove the excess water from each specimen

by placing them ventral margin down on a towel until the valves

opened slightly allowing the excess water to drain. The shells were

again weighed after the soft parts were removed in order to deter­

mine the percentage of shell weight for each individual. The gills

were examined for glochidia, and the foot-gill sinus and pericardial

cavity were posted for parasitic or commensal symbionts such as

flukes, mites, and leeches.

In addition to the weight noted above, the specimens from

several of the 1956 collections were weighed while suspended in water

so that the specific gravity might be calculated*

Measurements of length, height, and width of each specimen

were also made and recorded. It was thought best to follow the

methods of measurement used by previous authors so that the bay forms

could be compared with those from other localities and, in cases of uncertain identity, with the dimensions and proportions of the types* 2 k

An examination of the terms and methods used in early descriptive work

revealed some gross differences among investigators. Many authors neglected to describe the nature of their lengths, widths, heights, diameters, breadth, and axes. According to Barnes (1823:112) Lamarck considered "the beaks as the base, . . ." and was not alone in term­ ing that side of the beaks having the ligament as anterior. This explanation helps greatly in understanding Lamarck’s descriptions*

Barnes quotes Say who encourages a reversal of the terms anterior and posterior in order to conform to the definitions of Cuvier and to have the mouth at the anterior end as it "ought always to be con­ sidered. " In spite of the logical plea of Say, Barnes and others

(e.g., Hildreth, 1828) followed Lamarck's usage of anterior and posterior, though Barnes does consider the beaks to be dorsal. In order to avoid deciphering these older descriptions on the occasion of each reference a table of terms was constructed for ease of interpretation. The decision to use the terminology of Call (1900) and McMichael and Hiscock (1958) was made in view of the facts that they are in common usage todsy by most naiadologists and easily understood by workers in related fields. Definitions of the dimensions measured are given below since a word such as "length" may have several meanings:

(1) length parallel to the ventral margin (2) length parallel to the dorsal margin (3) length parallel to the hinge line (k) length parallel to the u m b o n a lslope

The dimensions taken in this study are defined below. 2$

Length is the maximum antero-posterior dimension of the shell.

It has been found to be roughly parallel to the hinge line in all

the species here studied.

Height is the maximum dorso-ventral dimension of the shell

measured at right angles to the length. This dimension does not

include the ligament, umbones nor the wing in the alate species,

Proptera alata (Say) and Leptodea fragilis (Rafinesque)• The so-called

wing or post dorsal ridge of the other species dealt with here in in­

cluded. It is believed best not to include the structures listed

above because in many (if not most) instances they are eroded, broken,

or both. This measurement usually can be made best from the inside

of the valve. In the cases of P. alata and L. fragilis the height

is measured as described above except that the umbonal slope is con­

sidered the dorsal limit. The high point of the umbonal slope in

both species is almost always just a short distance posterior to the beaks proper and approximately the level of the lateral tooth in the

right valve or the lateral tooth sulcus in the left valve.

Width is the maximum transverse dimension of the shell with both valves in normal position and includes sculpturing, when present.

The measurements of length and height care made with the use

of a clam board, constructed for this purpose, with a Glogaivernier caliper or with a pair of needle-point dividers and a linear metric rule. The clam board was outfitted with a metric grid and with two metric scales placed at right angles and meeting at the lower left TABLE 1. INTERPRETATION OF TERMS USED BY NAIADOLOGISTS IN DESCRIPTIVE STUDIES

Modern Say Lamarck Rafinesque Barnes Lea Hildreth Conrad DeKay Term 1817® 1819® 1820® 1823 1828 1828 I836 18U3

no measure* no measure- transverse Length breadth breadth breadth breadth breadth ments given ments given axis

no measure­ no measure- vertical Height ments given len9th length length length length ments given axis

no measure­ no measure— Width ments given diameter diameter diameter diameter ments given diameter

Anterior anterior** posterior anterior posterior anterior posterior anterior anterior

Posterior posterior anterior posterior anterior posterior anterior posterior posterior

dorsal or hinge or dorsal ligament Dorsal base or hinge dorsal dorsal dorsal back (margin) (margin) (margin) (margin) basal® upper basal basal basal lower Ventral (edge) (margin) (margin) basal basal (margin) (margin) (margin) TABLE 1 (contd.)

Clench and McMichael Modem Call Simpson Utterback Qrtmann Baker Baker T*§§gr “ djH^cock Tern 1898 1900 191U 1915 1919 1928

Length length length length length length length length length

Height height height height height height height height height

Width breadth width? diameter diameter diameter diameter breadth width

Anterior anterior anterior anterior anterior anterior anterior anterior (before)

Posterior posterior posterior posterior posterior posterior posterior posterior

Dorsal dorsal dorsal dorsal dorsal or dorsal dorsal dorsal (line) upper

Ventral ventral ventral ventral (l“ e) ventral ventral TOntral TABLE 1 (contd.)

Say reverses the position taken here and uses Lamarck's reverse terminology in his American Concology (l830:pl. 22).

^From translated quotes of Barnes (1823) or from quotes of Call (1900).

eFrom translationcf Poulson (1832). £ Occasionally uses breadth or diameter.

I interpret the "axis" dimension of Rafinesque to be the lengthcf a line passing from the dorsal to the ventral margins at right angles to the length (breadth of Rafinesque) at a point midway between the anterior and posterior extremities. 29

corner. A transparent hairline T square was used to eliminate parallax

error. This method was most convenient, the calipers most precise,

and the dividers most rapid. All measurements of length and height

were taken at, or rounded off to, the nearest millimeter. The width

in every case was taken with the vernier caliper and each figure was

rounded off to the nearest millimeter with the exception of those

less than ten millimeters, and these were taken to the nearest tenth

of a millimeter. The flexible periostracum, extending beyond the

anterior, ventral, and posterior shell margins in all but the smallest

specimens, was such that consistent readings of an accuracy greater

than the nearest whole millimeter were inqjossible for any but width

measurements.

Data for the age-length graphs were obtained by measuring each

annulus possible on every specimen. Length only was measured for

each year; thus, each specimen yielded as many items of length data

as it was years old. This was accomplished using needlepoint

dividers and a metric scale calibrated in millimeters. If the speci­

men being measured had been collected during the winter months of

November, December, January, February, or March the margin of the

shell was considered to be the last annulus. Shell margin measure­ ments of individuals taken during the growing months from April to

October were not used in the growth study. Lake Erie naiades are well known for the regularity and distinctness of their annul! or

annual growth rings (Ortmann, 1919:22) (Grier, 1920:15k; 1922:132).

These rings, much like those found in tree borings, on fish scales, 30

vertebral sections, etc., are produced by changes in growth rate.

The well-defined and regular nature of the annul! of Lake Erie

naiades may be a result of the greater stability of the lake when

compared to stream conditions. This is suggested by Grier (1922:132)

and he gives evidence which supports this inference. While the

annuli of lake-dwelling naiades may be more easily read than those

of the same species in most streams, there are still difficulties to

be overcome and pitfalls to be avoided. Lake Erie naiades are not

exempt from false annuli which may be produced at any time during the

growing season when the mantle margin is withdrawn to the extent of

breaking contact with the edge of the shell where new periostracum

and prismatic layer are being deposited (Coker et al., 1921:131).

A seiche which exposed the mussel to the air for several hours might

produce a false annulus. Fortunately most, if not all, false annuli

present on Lake Erie specimens may be recognized by a combination of

the following characters:

(1) The make-up of the material of which the false annulus is

composed (i.e., color, texture) is usually quite different from the true annulus and may be quite different for some species. False

annuli are almost without exception much thinner.

(2) False annuli are generally incomplete, not extending from anterior to posterior dorsal margin in the unbroken, uniform manner of a true annulus. 31

(3) False annuli are not flanked by the type of periostracum

associated with the cessation and resumption of growth as is the true

annulus. The color (and perhaps the thickness) of the periostracum

changes as winter approaches in many species. The reverse color

change is observed in the spring. Individuals with shell rays fre­

quently lay down unrayed periostracum in late fall and early spring.

This produces interrupted rays on the disc and the true annuli pass

over the surface of the shell between the interruptions while the

false annulus passes through them.

(U) The true annuli of any particular species from any

particular habitat have a relatively uniform spacing or periodicity

which is the same from specimen to specimen of the same age or be­

tween individuals of different ages if the comparison is made between

those annuli which represent the same ages. This periodicity changes

in the naiad, indicating a rapid growth rate as a juvenile, a moder­

ate to slow growth rate as a sexually active nature adult, and the

development of a very slow rate ot the outset of senility when

reproductive activity begins to decrease. Once the worker learns

the periodicity pattern of a species for a particular habitat he can

easily identify an annulus out of position, and he may suspect any

such annulus of being false. If the annulus on either side of the

one in question is "in place" and satisfies the predicted sequence,

and if some or all of the above conditions— (1), (2), (3)— are found

to prevail, the annulus is pronounced false and is neither counted nor measured. 32

It should be noted that the above observations concerning false

annuli were not made at the beginning, but were developed during the

course of this study. It should not be concluded that the criteria

used in this study to identify false annuli will be effective every­

where. In even a few of the Lake Erie shells there remains some

doubt concerning the validity of a feu of the annuli. These in­

stances— fortunately rare— were confined to either very old specimens

where the annuli were so close together they almost overlapped or to

a few young specimens which apparently passed through a winter marked by an atypical annulus. Since the position of this annulus was, in

each of the several cases, well marked by the usual color change which accompanies the winter rest period, the annulus was counted

and measured even though it was atypical.

A light was used in the manner suggested by Chamberlain (1931:

715) to aid reading the thin to moderately thick shells, when such a

technique proved advantageous. This was of particular value in

specimens where the annulus on the surface was partially worn away.

The transnitted light made even these lines stand out in bold relief.

A number of individuals had eroded umbones with the resultant

loss of one or more annuli in a region where the use of transmitted

light was not possible due to the thickness of the shell. This was especially true of older specimens from the soft bottoms in deep water. At first it was thought that these individuals would have to be passed over, and that, as a result, it would be ingrossible to study growth rate during senility or to make any estimates of longevity in 33 some species. It was found, however, by knowing the general periodic- ity (of the annuli) of the species and by noting the spacing repre­ sented by the remaining annuli on the specimens in question, the probable number of missing annuli could be estimated. This procedure was followed and lengths were taken in the usual manner from all specimens having three or fever annuli missing. Where the eroded zone involved an estimated four or more annuli the shell was passed over and no growth data were taken. By proceeding in this manner it was found that successive annuli outside the eroded zone fell into the respective length ranges of the age groups to which they had been assigned. Some time later an eroded specimen was studied which had the "missing" annuli of the eroded area boldly represented by well- defined curved ridges in the exposed nacreous material of the shell.

A close inspection of the eroded shells previously studied revealed in almost every instance the number of estimated missing annuli represented by fine curved lines or grooves at or very near to the position expected on the basis of periodicity*

Treatment of Data

An extensive search of the literature was required to bring together the background of information necessary to treat each of the species or complexes in the proper perspective. The Naiadacea of the

North American Great Lakes have never been monographed. The same is true for Lake Erie, as such waters of the State of Ohio. Fortunately there exist such comprehensive works for Indiana (Call, 1900), 31*

Pennsylvania (Ortmann, 1911 and 1919)* Missouri (Utterback, 1915-

1916)* and Wisconsin (Baker* 1928). These studies and other papers

of greater and lesser scope vere freely used in developing a

knowledge of North American Naiades in general and those of the upper

Mississippi and Great Lakes drainages in particular. It is believed

that such a background is necessary for an understanding and appre­

ciation of the origin* distribution* and present relationships of

the Lake Erie naiad fauna. Items such as synonoraies, nature and

location of types* previous records* and descriptions have been

included in this study of the Unioninae. The following discussion

concerns the treatment of data beneath each species heading*

Scientific names* A complete scientific name, if it is to be

an effective reference* should be followed by author and date. Some writers* in referring to the later use by one author of a certain

scientific name coined earlier by another writer* omit the name of the describer but follow the trivial name with the name and date of the user referred to. This practice is quite common in early liter­ ature. The confusion arising by such a procedure can be avoided and the reader directed to the referred instance(s) of usage by adding the author* date* and a period to the Latin name* and following this by any number of desired references to the usage of this particular combination. In this manner* Fusconaia undata rubiginosa (Lea* 1829).

Ortmann (1913*291) means that the form rubiginosa* described by Lea in 1829* was referred to as a subspecies of Fusconaia undata by

Ortmann in 1913* This policy has been followed in this paper* 3*

Synonomy. The Descriptive Catalog of the Maiades (Simpson,

191U) contains what is probably the most complete grouping of naiad synonomles in existence and has been used as the principle reference in constructing the synonomles listed here. An attempt was made in this study to include in the synonomy every name under which the species has been known. In each case an effort was made to cite the earliest reference but no others. The result is a "name synonomy" rather than a “bibliographic synonomy,” and is reasonably complete down to the year I960.

Type Locality. The type locality was determined by reference to the original description or, that being unavailable, by reference to a subsequent author's citation.

Type Specimens. None of the holotypes of any of the species studied has been examined. All references to the nature of type material in existence, and its location, have been obtained from the literature. The only exceptions to the above are the cases of Amblema plicata (Say), Proptera alata (Say), and Ligumia recta (Lamarck).

The Lake Erie specimens of these species are topotypes.

Lake Erie Records. Only published records are included in the following lists. Although it is certain that these lists for Lake

Erie could be supplemented by a study of museum material there seems little possibility of adding to the knowledge of the Fishery Bay fauna through such an undertaking.

Shell Character!stics. It is surprising in view of the fact that so many lake ecoforms have been given specific or subspecific 36

rank, that there are so few comprehensive descriptions of these unusual naiades in the literature. Most of the descriptions refer

only to the few characters necessary to separate the lake from the

stream forms (Grier, 1918). Since no new taxonomic forms are des­

cribed here-in, all descriptions pertain to the collected material

of a species as a unit, and represent a composite of a particular

form in a particular habitat rather than an individual. Measure­ ments and the proportions calculated from them are treated in like manner to show the range of variability and to permit comparison of at least some characteristics with non-lake material on a quantita­ tive basis.

Two proportions were calculated from the raw data of length, height, and width. These were computed for each shell so that these specimens might be compared with others on bases other than size alone. This seemed particularly important in view of the stunted nature of the ecoforms.

The first proportion was found by dividing shell height by length. This expression of relative height was multiplied by a factor of 100 and termed the height index. It can be seen that a round shell or a square shell having its length equal to its height would have a height index of 100. A shell twide as long as high would have a height index of 5>0, its height being S>0 per cent of its length.

The second proportion was found by dividing the shell width by length. This e}q>ression of relative width was multiplied by a factor 37 of 100 and termed the width index. A specimen having a width index of

100 would be as wide as long while an index of 7$ would indicate a width of only 2J> per cent of the length. These were chosen because the two variables most frequently mentioned as changing in a pre­ dictable manner from the headwaters in a downstream direction are relative width and relative height. Ortmann's conclusions (1920:310) follow:

1. the more obese (swollen) form is found farther down in the large rivers, and passes gradually, in the upstream direction, into a less obese (compressed) form in the headwaters;

2. with the decrease in obesity often an increase in size (length) is correlated;

3. a few shells which have, in the larger rivers, a peculiar sculpture of large tubercles, lose these tubercles in the headwaters.

Ortmann presented a wealth of data in support of these con­ clusions. They have held up so well that today they are referred to as Ortmann's Laws. The laws are found to be particularly true for the so-called primitive genera— Fusconaia, Amblema, Quadrula, and

Pleurobema in the Unioninae and Dromas and Obovaria in the

Lampsilinae (Ortmann, 1920:311)*

Two tables were utilized for each species in presenting the results of this limited quantitative treatment. The first table presents the means and extremes of the measurements made and indices calculated. The range was added as a matter of convenience. It was observed that proportions sometimes changed with size and a second table was provided in which the specimens were treated in length 38 groups. A ten millimeter length interval was chosen for ease in handling data. This technique proved valuable in groups in which the sample size was relatively large (50 specimens or more) but left much to be desired in those groups represented by a small series.

This 'was particularly true in the Unioninae. Fortunately, material from other locales in western Lake Erie was cm hand and used to supplement the bay specimens in the general treatment. Only certain species in the Subfamily Lampsilinae exhibit sexual dimorphism in the shell and in these species only the data is broken down into the categories of juveniles, females, and males.

Plates. Each species is illustrated by a plate of a typical or near-typical Fishery Bay Specimen. Only one specimen was used as a model for each figure. The few instances where specimens from outside the bay are used are so noted. Each drawing was made using a 1:1 scale and was neither enlarged nor reduced. These plates are not free-hand drawings.

The following procedure was used in constructing all plates.

(1) The valve was centered on the paper and the outline traced lightly with a pencil. Small marks were then made about the margin noting such fixed points as end of ligament, highest point of beak, and intersection of rays with shell margin. The shell was then removed to one side and the exact process repeated on scratch paper.

(2) A system of polar coordinates was laid out on the drawing with a straight edge using the high point of the beak as the origin 39 from which six to eight straight lines pass out to the traced margin.

Distances from the origin along the lines mentioned were taken from the shell with dividers and transferred to the drawing. In this manner the precise position of each annular ring and ray was deter­ mined and penciled in.

(3) Once the shell outline, growth lines, and rays were positioned they were inked in using India ink and a crow-quill pen.

(U) Following the gross inking, fine ink lines were added between those already drawn to show contours and sculpturing.

Habitat Distribution. Notes were taken at the time of each collection concerning the location of the collecting site and, when possible, the associated fauna and flora. The collection site data were later used to determine depth and nature of substrate. Each specimen taken is represented on the. distribution map as a spot and the map may be compared to those showing nature of substrate and depth contour lines to note nature of distribution with respect to these factors. The same base map is used in each case for each of comparison.

Growth and Longevity. The published studies dealing with the use of growth rings in the determination of the age of fresh water mussels date back to the work of von Hessling (1859). He was unable to confirm the annual nature of these rings but he aroused the interest of Hazay (1881) who established the existence of a single growing period each year and verified the intervening rings as being of an annual nature. Israel (1911) concluded, after a study of mussel UO

shell margins collected at various seasons of the year, that there

was no winter rest period and that more than one ring may be formed

in a single year. These results quite understandably cast doubt

upon the validity of the growth ring technique of aging. Lefevre

and Curtis (1912), in the first North American work in this field,

were aware of Israel's conclusions and expressed their own doubt

in the following manner:

Assuming that these rings, when clearly seen, do represent years, it would seem that the shell grows very rapidly during the first few years of the mussel's life and after that much more slowly. To judge from the lines alone, we should say that many of the large Quadrula shells had reached one-half their size in ten or a dozen years and then taken forty or fifty for the remainder, so closely set are their later rings of growth; and that shells of these species can not reach the most desirable commercial size in a less period than twenty or thirty years.

These speculations, based on uncertain information eventually proved

to be true; but, uncertainty and the exercise of perhaps justifiable

caution prevented their general acceptance for almost twenty years.

Grave doubts of their validity still exist in the minds of some

(Shuster, 1957:5)* If the value of this technique had been recog­ nized the fresh water pearl buttom industry might have been saved.

In the twenty years following the paper by Lefevre and Curtis the commercially valuable naiad populations of the Mississippi and Ohio basins were all but extirpated by the clammers. It is questionable in view of the inroads of pollution and dam building (and despite the aid of too late protective laws) whether the naiades will ever return to their former abundance. These same workers (Lefevre and lu

Curtis, 1912:180) planted cages of mussels in the Mississippi River

during a period of two winters. One cage was recovered by Coker.

Lefevre and Curtis quote his observations:

Furthermore, the added area of shell is divided fy a conspicuous dark ring and a less distinct ring which, one is tempted to assume, represent the periods of cessation of growth during the two winters. If such an interpretation is made, the growth was accomplished chiefly during 1908 and 1909, while during the present year (1910), the mussel having reached adult size, the growth has been considerably less.

These observations and those cited above are so characteristic

of these forms that it is difficult to understand why they were not

immediately followed up.

Isely (191U) concluded that the "arrested growth rings" were

sufficiently regular and definite to be used as age indicators but

declined to use them in his own work. The nature of the annulus

and its mode of origin were investigated by Coker et al. (1921:129).

It was found that, although annul! were laid down over winter, a disturbance such as the act of measuring a specimen during the growing

season might also produce a ring. The winter annuli were noted as being darker than the false annuli.

The first growth study of lake dwelling naiades was made by

Grier (1922) using Lake Erie specimens from Presque Isle Bay,

Pennsylvania; Cedar Point, Ohio; and La Plaisance Bay, Michigan.

Grier reasoned that, since environmental conditions were fairly uniform in Lake Erie, fairly uniform naiad growth would result and that "the number of rings of growth on the shell could be reasonably conceived to represent the number of years the animal has lived." U2

He measured a number of Shell dimensions and recorded the age of each specimen. In the absence of any statement to the contrary I assume that all annuli upon any one specimen were counted in arriving at the estimated age. The data are presented in tabular form (Tables 2, 3) with the mean length of each age group represented as a percentage of the length at two years. Twelve species are dealt with and the sample size of any one year group varies from zero to a maximum of four. It was noted that none of the shells studied had reached extreme old age* although ages as great as nineteen years were reported for two species, Lampsilis ventricosa (Barnes) and Lampsilis siliquoidea

(Barnes), and a maximum of 22 years was listed for a specimen of

Proptera alata (Say). While graphs of growth (length vs. age) were not constructed, the data necessary for the plotting of such curves were calculated from Grier's tables and are presented here for com­ parison with the results of the present study.

Grier's comparisons of growth rate demonstrated that the hard shell forms were slow growing (6.8 mm./yr.), the thin shell forms rapid growing (9 mm./yr.) while the intermediate Lampsiline species had an intermediate rate (8.2 mm./yr.). In comparing the lake dwelling forms with those of the streams studied by Coker et al. (1921) he noted, as had those investigators, that the most rapid growth occurs early in life while the growth process slows down considerably with age.

An improved technique for age-growth studies was introduced by Chamberlain (1931) in a thorough study of four species of naiades* Every true annulus on each specimen was counted and measured with the

result that each individual yielded a datum for every year of age.

Although this procedure is far more laborious and time consuming, it

has the added advantage of having each length measurement made on the

shell where the margin had been at the end of the growth period of

that particular year. Mean lengths are calculated for each annulus

of each species and these are plotted against age (determined by the

annular ring method) on graphs. These graphs are, as far as I have been able to learn, the first such representation of the relationship of age and growth in fresh water mussels. Chamberlain's mean length data have been rounded off to the nearest millimeter and reorganized

in tabular form for purposes of comparison with the results of other workers (Tables U, 5)» The methods used by Chamberlain in obtaining data from specimens, calculating means, and presenting the results

in tabular and graphic form, in all essential points, are followed in the present study. The effects of diverse environments on the growth rate of a single species was revealed in Chamberlain's work on the yellow sand shell, Lampsilis anodontoides (Lea). Male specimens from the Mississippi River at Fairport, Iowa, averaged 16 mm. in length at the end of the first year, while those from White River,

Arkansas averaged 28 mm. and speciments from the Rio Grande Valley,

Texas had attained a mean length of 1*6 mm. during the same period.

A higher average temperature coupled with a longer growing season seem to be two likely factors capable of producing this effect. TABLE 2. AGE AMD GROWTH DATA OF LAKE ERIE NAIADES3

Mean Length in Millimeters Annulus Number I II III IV V VI VII VIII IX X XI XII XIII XIV XV XVI XVII XVIII XIX

Fuscenaia N 0 1 3 1* 1* 1* 1* 1* i* 2 2 2 flava L mm 17 31 31 33 1*8 1*9 55 5U 52 51 60 -

Amblema N 0 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 plicata L- 21 25 35 U2 53 61 62 66 72 56 72 76 87 87 86 mm

Pleurobema N a. 0 0 0 0 0 0 2 2 2 2 2 cordatum L ------58 61 67 67 69 -

Elliptio N 0 1 1 2 2 2 0 1* 1* 1* 1* 1* _ dilatatus L- 21 26 1*7 51 1*5 «■ 71 71 77 80 80 -

Lampsilis N 0 0 0 0 0 l 2 2 2 3 3 3 3 3 3 3 2 2 1 siliquoidea L - mm - - mm 51 56 51* 57 69 73 79 55 82 71* 75 85 78 85

Lampsilis N 0 0 0 2 0 0 2 2 1* 1* 1* 1* 1* 1* 1* 1* 1 0 1 ventrfcosa L * •* m 19 •• * 63 52 60 65 67 80 72 79 81 87 96 90

N ■ number of specimens. L * mean length in mm.

a Recalculated from Grier (1922) TABLE 3. ACE AND GROWTH DATA OF LAKE ERIE NAIADES3

enBM BBBaKaaaeEsaBBBEnBXCsm nM HnHBasEaBM BM aB Mean Length In Millimeters Annulus Number I II Ill IV V VI VII VIII IX X XI XII XIII XIV XV XVI XVII XVIII XIX XX XXI XXII

Anodonta N 0 0 0 1 1 3 3 3 3 grandis L --- 53 75 92 87 8U 86 -

Anodontoides N 0 0 2 2 3 3 3 3 1 _ /erussacianus L - mm U8 53 61 67 69 72 77 aa

Lasmigona N 0 0 0 0 0 2 2 2 2 2 . costata L - - - - flB 7k 75 8U 83 85 -

Leptodea N 0 0 1 2 2 k h U U 0 0 k fragilis L -- kh 55 98 90 92 89 85 - am 12 9 am

Proptera N 0 1 1 0 1 1 1 1 2 2 0 1 1 2 2 1 0 0 0 1 0 1 alata L m 13 1U - 13 33 26 U8 U9 66 - 90 86 67 110 96 - - - ioU - 101

Ligumla N mm 0 0 0 0 0 0 0 1 2 2 2 1 1 2 2 1 1 recta L ------mm - 61 95 89 89 109 116 90 111 95 ioL -

N ■ number of specimens. L - mean length in nun.

Recalculated from Grier (1922). TABLE 1*. AGE AMD GROWTH DATA OF NAIADES®

Mean Length in Millimeters Annulus Number 1 II III iv V VI VII VIII IX X XI XII XIII XIV XV

Lampsilis N 100 100 100 97 57 20 9 ahodontoiaes cf L 16 55 82 96 10U 113 119 M (from Ioura) N 100 100 100 100 92 33 10 3 - Q CM + L 16 52 85 100 108 115 119 1

Lampsilis * N 50 50 hO 2U 7 U h 2 - anodonteides cf L 28 67 89 103 115 121 122 133 -

(from Arkansas) Q N 5o 50 h9 33 29 h L 3U 69 91 10U 110 HU -

Lampsilis N 56 56 k9 35 6 2 • anodontoides cf L U6 80 101 112 120 133 -

(from Texas) 0 N 26 26 18 5 1 1 + L k* 83 102 121 130 136 •

N * number of specimens. L ■ mean length in mm.

^Modified from Chamberlain (1931). TABLE 5. AGE AMD GROWTH DATA OF NAIADES®

Mean Leaoth in Millimeters Annulus Number I II tti iv V VI VII VIII IX XXI tfii XIII XIV XV Lampsilis N 200 200 200 200 196 185 132 85 k6 25 8 3 1 - s'iffquoidea CF L 20 UO 56 68 77 83 87 91 93 9k 93 97 106 -

(from Lake Pepin Q N 200 200 200 200 192 139 86 30 17 7 1 m Minn.-Wis.) L 20 U3 57 66 72 76 79 80 81 85 86 -

Lampsilis d* N 100 100 100 100 100 97 85 60 33 10 U 1 s'ilfquoidea L 23 39 51 62 71 77 82 87 90 93 97 98 - (from Crosslake o N 100 100 100 100 100 100 73 32 12 2 m Minn.) + L 20 3k k9 60 67 72 76 79 8U 86

Tritogonia N 16 16 16 16 16 16 16 16 2 1 1 - verrucosa and (jfrom Iowa) 9 L 15 3k kh 5U 60 66 73 78 96 110 HU - Unio pope! a N 7 7 7 5 2 1 and (from Texas) 9 L 3U 66 8U 96 108 118 • N ■ number of specimens* L ■ mean length in mm.

Modified from Chamberlain (1931)* TABLE 6. AGE AND GROWTH DATA OF LAKE ERIE NAIADES8,

Mean Length in Millimeters Annulus Number I II III IV V VI VII VIII IX X XI XII XIIIXIV XV XVI XVII XVIII Elliptio N 1 1 1 2 U S U 7 6 3 6 3 dilatatus L 20 27 39 US Si SS 61 69 71 7S 73 77 - (fishery Bay)

Elliptio N 0 1 1 1 l l 0 3 6 S 2 8 2 3 1 2 dilatatus L 28 33 39 US S7 S3 S8 S7 S6 61 6U 66 63 6S - (?elee Island)

Ptychobranchus N 0 1 2 7 0 3 2 1 2 3 3 2 3 2 3 0 0 1 fasciolaris L 33 3U 37 US U7 U8 SO S3 63 62 60 S7 67 67 (Fishery Bay)

Ptychobranchus N 0 1 1 2 i 2 0 1 2 0 2 fasciolaris L 31 30 39 U8 U7 SI SS S6 - (Pelee Island)

N ■ Number of specimens* L “ Mean length in mm*

Modified, from Brown et al. (1938). Brown et al. (1938) utilized Grier's method of obtaining data from specimens in their study of the relationship of growth and habitat. Their age-growth data are presented here (Tables 7-9) in the same manner as those

Ptychobranchus fasciolaris (Raf.) and Ligumia nasuta (Say). TABLE 7. AGE AND GROWTH DATA OF LAKE ERIE NAIADESa

Mean Length in Millimeters Annulus Number I II III IV V VI VII VIII IX X XI XII XIII XIV XV XVI XVII XVIII

Ligumia nasuta N 2 0 5 7 8 2 h 1 (East Harbor) L Ui mm 66 72 85 101 88 96 -

Ligumia nasuta N 0 0 1 0 0 1 0 1 1 0 0 0 0 1 - (Fishery Bay) L - - a - - 80 - 65 78 - - - - 76 -

Ligumia nasuta N 0 1 0 0 1 (Pelee Island) L - 39 - mm 60 -

Ligumia recta N 2 0 5 7 8 2 U 1 (East karfcor) L Ui - 66 72 85 101 88 96 -

Ligumia recta N 0 0 1 0 0 1 0 1 1 0 0 0 0 1 - (Fishery Bay) L - mm 5U - at 80 - 65 78 - - - - 76 -

Ligumia recta N 0 1 0 0 1 mm (Pelee Island) L - 39 - - 60 -

N ■ Number of specimens* L ■ Mean length in mm.

Modified from Brown et al. (1938). TABLE 8. AjE AND GROWTH DATA OF LAKE ERIE NAIADES*

Mean Length in Millimeters Annulus Number I II III iv V VI VII VIII IX X XI XII XIII XIV XV XVI XVII XVIII

Proptera alata N 0 2 2 h 11 15 1U 11 5 2 1 2 0 1 - (East Harbor) L - 61 72 85 92 96 111 115 119 117 130 113 - 92 -

Proptera alata N 0 0 ii 2 S 6 2 2 - (Fisliery Bay) L 73 69 87 98 103 99 -

Proptera alata N 0 U 11 17 11 ' 2 0 0 1 ..(Feiee island L - 39 50 6U 71 75 - - 8U tm

Leptodea fragilis N 0 1 6 11 11 6 2 - (East Harbor) L - 77 105 113 119 122 130

Leptodea fragilis N U 1 5 5 1 1 0 0 0 0 0 1 - (Fishery Bay) L 30 53 68 88 98 103 - - - 111 -

Leptodea fragilis N 0 3 U 9 3 3 1 2 2 •• (Pelee Island) L - U2 59 7U 82 86 91 100 101

N ■ Number of specimens. L * Mean length in mm.

£ Modified from Brown et al. (1938). TABLE 9. AGE AND ®OWTH DATA OF LAKE ERIE NAIADES3

Mean Length in Millimeters Annulus Number I II III IV V VI VII VIII IX X XI XII XIII XIV XV XVI XVII XVIII Lampsilis N 0 0 2 8 19 51 27 12 7 3 2 a. siliquoidea L m - 6h 81 85 86 91 91 97 85 103 - (East harbor}

Lampsilis N 0 0 10 IS 9 12 13 8 h 2 U 1} 2 0 1 siliquoidea L -- 56 SB 61 70 68 70 81 83 76 77 91 - 90 «■ (fishery Bay)

Lampsilis N 1 1} h 12 15 11 6 6 1 2 mm siliquoidea L 20 ho U7 57 59 61 66 65 68 72 mm (Pelee island;

Lampsilis ovata N 0 0 1 0 1 2 2 1 1 «■ ventricosa L _ — 70 - 69 86 95 100 107 • (East Harbor) Lampsilis ovata N 0 l 2 0 0 0 1 1 0 1 2 2 1} 0 0 0 0 1 ventricosa L - 55 62 - - - 85 82 - 87 97 85 95 -- 96 (Fishery Bay; Lampsilis ovata N 2 5 7 10 10 10 lit 17 17 lh 8 1 3 2 3 _ ventricosa L 38 52 61 65 68 72 73 76 78 82 85 76 82 82 88 - (Pelee Island) N ■ Number of specimens* L * Mean length in mm. Modified from Brown et al. (1938!). THE PHYSIOGRAPHY OF FISHERY BAY

General Characteristics

Fishery Bay is one of a number of harbor-like inlets found in

the Bass Island region of Lake Erie. It is located on the north

shore of the larger of two joined land masses which form South Bass

Island. This body of water has been referred to in the literature as

part of Put-in-Bay proper, as Fish Hatchery Bay, or as Hatchery Bay.

The principle harbor area at South Bass Island, if priority be our

guide, should be called Put-in-Bay Harbor since references in the

older literature are usually to the entire bay area as such and seldom

to any particular subdivision. The Put-in-Bay Harbor has at least

three rather natural subdivisions: Put-in-Bay proper, Squaw (Square)

Bay, and Fishery Bay. Fishery Bay is the most nearly isolated of the

three areas (Hap IV) being connected to Put-in-Bay and Squaw Bay across

Alligator Bar on the southeast and open to the lake itself at the

deeper northeast end. It is bounded on the northwest by Peach Point

and the submerged Peach Point Reef while its southeast limits are marked by Oak Point, Alligator Bar, and Gibraltar Island (Map V).

During strong prolonged southwest blows the lake level may drop three

to seven feet resulting in the emergence of the underwater extension

of Alligator Bar and the resultant near separation of Fishery Bay

from Put-in-Bay. The only water connection across the Bar at such 5U

times is that in a dredged cut having a normal depth of about seven to

eight feet. It is at such times that naiad collecting is at its best

since it is about the only time that specimens may be handpieked— each

from its respective habitat niche. The only unfortunate aspect is

that seiches of a five to seven foot magnitude come but once or twice

a year, typically in November and/or March and, with rare exception,

are accompanied by some of the harshest weather of the Island Region.

The general shape of the bay is roughly that of an elongate

isosceles triangle with the base being its communication with the open

lake and its apex the innermost extremity of Terwillegar's Pond. The

major axis of the bay corresponds to the altitude of such a triangle

and passes from the apex at the southwest end of Terwillegar's Pond

to a point midway between the can buoy marking the submerged end of

the Peach Point Reef and the northeast extremity of Gibralter Island.

The length of the bay, measured along the axis described, is 2,925

feet— just over half a mile. The greatest width of the bay, which

constitutes the base of the triangle, is found at its connection with

the lake and measures 1,217 feet— just under a quarter of a mile.

For purposes of this study the bay was divided into three more or less natural areas. These subdivisions are referred to here as the outer Bay, inner Bay, and Terwillegar's Pond. Each of these areas constitutes a somewhat different composite of habitat types which combined represents almost every type of bay habitat found in the Island Region* Mmdtmjit*

/ i » M u m s */t & A y

SOUTH BASS ISLAND

OATS' A9H.tr

MAP IV. THE BAY AREAS OF SOUTH BASS ISLAND, PUT-IN-BAY TNP., OTTAWA CO., OHIO 5 6

fEB • 60

Figure 1. Fishery Bay from the Air (Photography hy T. H. Langlois)

09 • 83d

Figure 2. Fishery Bay from the North (fhotography hy T. E. Langlois) figure 3* Alligator Bar— Normal Water Level (Photography "by T. H. Langlois)

figure 4>. Alligator Bar Emerged During Seiche (Photography hy T. H. Langlois) FEB • 60 Figure 5* Causevey Cut During Seiche (Photography hy T. H. Langlois)

FEB • 60 Figure 6* Alligator Bar Energed During Seiche (Photography hy T. H. Langlois) LAKE ERIE

HUNDRED FEET Pooch Point

% w m -

« • * • . • • A. A

GIBRALTAR ISLAND

SOUTH BASS ISLAND Oak Point

Distribution of Sediment Types

clay 6 ** 4 angular rocks MAP V. FISHERY BAY OF LAKE ERIE * A * and gravel

• • • . . ° o rounded rocks silt • • • o and gravel • • • • O o

sand boulders a 0 0 \n vo LAKE ERIE 21: HUNDRED FEET Pooch Point

GIBRALTAR ISLAND

SOUTH BASS ISLAND Ook Point

Depth Contours Interval

MAP VI. FISHERY BAY OF LAKE ERIE, PUT-IN-BAY TOP., OTTAWA CO., OHIO

o\ o 61

Terwillegar's Pond

The innermost extremity of the bay, known as Terwillegar's Pond and hereafter referred to as the pond, is separated from the inner bay by a causeway. A cut through this causeway allows water to flow in and out of this semi-impounded area in a seiche-like manner. The direction of flow is usually reversed every six or seven minutes, although it is known to vary from one to almost fifteen minutes

(Krecker, 1928:50* This apparently continuous surging action of the water through the cut has several effects which have a direct bearing upon this study. This cut is, first of all, primarily responsible for the pond remaining a functional part of the bay rather than develop­ ing a true pond flora and fauna and passing through the familiar serai stages to extinction. Descriptions of the pond as it existed half a century ago have led me to believe that this area is becoming less pond'-like with the passage of time. Several possible causes for this reversal of natural processes have come to my attention. The pond has been dredged on at least one (and possibly two) occasions with many tons of sediments being used to create "new land" in the comers of the pond and along the causeway. At a later date (19U2) nearly all woody vegetation was removed from the shores. While this latter action undoubtedly served to increase the rate of shore erosion it has done little to increase the rate of along-shore sedimentation*

It may be that the increase in lake level has produced stronger

"seiche" currents which have served to keep the original dredged channel around the center of the pond (Map VII) relatively clear of Figure 7. Terwillogar'» Pond— Normal Water Level (Photography by T. H. Langlois)

FEB • 60

Figure 8. Tervlllegar's Fond During Seiche (Riotography by T. H. Langlois) TjEGH/iLLEGAR'sP o n D OF FISHERY Ba y F/e e r /oo *00

Depth Contours Interval “ 3*

MAP VII. TERWILLEGAR'S POND OF FISHERY BAY, PUT-IN-BAY TOP., OTTAWA CO., OHIO 6U

sediment deposition. The water action through the cut has been of

such a nature as to perpetuate its existence. This is demonstrated

by the fact that the greatest pond depth is Just inside the bridge

which spans the cut and that the bottom beneath and for some distance

(l5'-20*) on either side of the bridge is of a firm non-shifting

coarse gravel grading away into finer sediments in either direction.

This cut has made possible the exchange of naiads, fish, cray­

fish, and other strictly aquatic fauna between the pond and the inner

bay. In spite of such opportunity of access, however, the pond has maintained a predominately pond naiad fauna.

The pond is the smallest subdivision of the bay having a total area of 2.k acres, or 9,780 square meters. Expressed as a percentage of the total study area this figure is 5*5 per cent. The greatest length of the pond is measured along the major axis of the bay pre­ viously mentioned and is about 630 feet. The greatest width measured at right angles to the above mentioned axis at a level Just inside the pond dock (Map VII) and is approximately 2*>0 feet. In early January of 195U the pond was sounded through the ice using a graduated white oak sounding rod. One hundred seventeen soundings were taken at spaced intervals (20*) dong a series of 16 transverse lines thus covering all of the pond except a small unfrozen area Just inside the bridge. Hater soundings from a boat established this latter area to have a depth of at least ten feet. These data were then used to plot contour lines of the pond bottom using a three-foot interval. It can be seen (Map VII) that these contour lines delineate three regions which < 6 together make up most of the pond area. The periphery of the pond extends from the eroding soil shores down over a silt or sandy silt substrate to a depth of about three feet. This shallow zone (10'-30') almost completely surrounds the pond and was at the time of the study, occasionally characterized by emergent rooted aquatic plants:

Saggittaria latifolia, Sclrpus americanus, and Pontederia cordata.

These beds of vegetation were interspersed with stretches of eroding shore line. This shore zone grades into the channel zone, which has a depth of three to five feet. This zone in turn surrounds an elevated shallow area in the center of the pond. The channel is characterized not only by its greater depth but by its relatively coarser; substrate of sandy gravel which becomes progressively finer as one moves toward the shore, toward the pond center, or away from the causeway cut up the channel toward the tip of the pond. Emergent aquatic plants are entirely absent from this zone which is characterized instead by a luxuriant growth of the submergent rooted aquatic Eel Grass (Valisneria americana) in those regions of strongest current. Along the margins of the Valisneria beds in the finer sediments are a variety of sub­ mergent rooted aquatics including Ceratophyllum demersum, Naias flexilis, Potamogeten crispus, Potamogeton Richardson!i, Potamogeton pusillus, Elodea canadensis, Heteranthera dubia and some ffyriophyllum exalbescens. The shallow center area (less than three feet in depth) was composed of the finest (and softest) sediments to be found in the pond. This unnatural deposit is due to the dumping of dredgings from the channel— much of the soil having originally come from the eroding 66

vineyards which drain into the pond. In midsummer this submerged

platform supports a dense growth of Mjyriophyllum exalbescens. This

renders a habitat ordinarily difficult to sample more difficult to

work.

Inner Bay

The inner bay is intermediate in both position and size. It

has an area of 18.U acres of 7k»600 square meters. The latter figure*

expressed as a percentage of the total area* is 1*2.0 per cent. The

inner bay is separated from the pond by the causeway* from the open

lake by the Peach Point Peninsula, and from Put-in-Bay proper by the

southwestern end of Gibraltar Island and Alligator Bar. The line of

demarcation between the inner and outer bays was somewhat arbitrarily

determined by extending a line from the tip of Peach Point to the

shore of Gibraltar Island— this line being drawn at right angles to

the Gibraltar Island shore. Such a line approximates the division of

that portion of the bay (called inner bay) that is protected by the

Peach Point Peninsula from westerly blows from the exposed outer portion of the bay here called the outer bay. It was found that this

feature of the physiography, in conjunction with the prevailing

climate (and the usual storms), bad a marked effect upon the nature of

the bottom types and bottom stability in the bay and* hence upon the habitat distribution of the naiad species in this area. 67

An examination of the chart (Map V) shows the inner bay (as

defined) to be somewhat squarish in outline and measuring about 1000

feet in length and averaging a little less than 1000 feet in width.

The greatest depth located in the inner bay was Just over 16 feet and was found at a point about midway between the tip of the Peach

Point Peninsula and Gibraltar Island just inside the line of demarca­

tion between the inner and outer bay (Map VI). Moving from this point toward Gibraltar Island the water gradually becomes shallow so that the depth becomes less than three feet in approximately four hundred feet traversed. Moving in the opposite direction (i.e., toward

Peach Point) the depth decreases rapidly and the three foot contour is passed in less than one hundred feet. The reason for this becomes apparent after one has witnessed a heavy blow from the west. Waves coming across the lake strike the end of Peach Point, roll over the shallowly submerged reef and plunge into the relatively quiet bay on the other side. These waves have scoured a basin about three hundred feet in diameter and 21-23 feet deep on the lee side of the base of the reef. Most of the rocks and gravel have been washed out of this submerged plunge pool leaving a hard pan clay bottom. The bulk of the material quarried in this manner has been thrown up into an elongate gravel bar which extends ffom the inside of the tip of the point back into the inner bay at an oblique angle. A large part of this bar is separated from the point by a Shallow channel and, although it is usually submerged beneath six to twelve inches of water, it may be exposed for months at a time during seasonal low lake levels. This 68

sometimes emergent gravel bar has come to be known as "Hartlbb's

Island." The bar shifts position somewhat vith every heavy western blow and only one living naiad was taken from this area during the

study. This was an unusually heavy shelled specimen of Anodonta grand!s which had become wedged in between several large rocks. In comparing inner bay soundings made in 195k with those made in the same places by the U. S. Lake Survey in 1936 it was found that the bar had apparently become larger and had moved.

It can be seen that Hartlob's Island in conjunction with the

Peach Point peninsula protects a large part of the inner bay from the action of the prevailing winds. The resultant area of quiet water has probably been one of the major factors producing the silt bottom found there.

The bottom of the inner bay may be divided into three major sediment zones: (1) silt, (2) sand, and (3) sancty gravel strewn with water worn rocks and occasional boulders. Passing from the deep point mentioned and moving toward the end of Oak Point, the depth decreases slowly to less than two feet at the sea wall which surrounds the point. The same would be true in passing to the shore in almost any direction from the 18 foot depth except along the Peach Point dock front where dredging has resulted in depths as great as eight to ten feet in some places. The silt area previously mentioned is surrounded by a belt of rather firm non-shifting sand which grades shoreward through a sandy gravel zone into the rubble area described as (3) above* These last two areas proved to be the most productive in 69 numbers and species of naiades. A deposit of shifting sand along the

Oak Point sea vail was searched in vain for naiades with little success*

The few specimens found gave the appearance of having been washed into

the area from elsewhere.

The submergent rooted vegetation appeared to be related primarily

to depth and the nature of the substrate. The substrate in turn seemed

dependent upon the prevailing current, nature of storm action, and

types of available sediments. The silt bottom area was characterized

each summer by a luxuriant growth of Myriophyllum exalbescens which

occasionally reached the surface from depths of eight to ten feet.

Sandy areas were generally clear of rooted aquatics while the sandy

gravel bottoms were very productive. These latter substrates in

shallow water supported a variety of Potamogeton species, Maias flexilis

Ceratophyllum demersum, and occasionally Elodea canadensis and Heter- anthera dubia. Depths less than five feet exhibited particularly good growths of these aquatics. In depths over five feet these rough bottom areas frequently had extensive patches of Valisneria americana, the common eel grass. These patches were sometimes dense enough to prevent dredging work. It was not uncommon to pull up a fouled dredge from 18 feet of water and find it loaded with Valisneria even though no trace of the plants could be seen from the surface. It would seem that eel grass is able to persist tinder a lower light intensity than the other rooted aquatics of the bay area* 70

Outer Bay

The outer bay is bounded on the one side by the rugged cliff-

Shore of Gibraltar Island and on the other side by a somewhat less

effective barrier, the submerged Peach Point Reef. The inner margin

of this part of the bay communicates broadly with the inner bay while the outer end is continuous with the open lake*

The outer bay is the largest subdivision of the Fishery Bay and has a total area of 23*0 acres, or 93,300 square meters. Although this subdivision constitutes 52.£ par cent of the total study area, far less than $0 per cent of the total effort involved was expended upon it. The depth, turbidity of the water, and nature of the sub­ strate rendered collecting an all but impossible task by either dredg­ ing or diving.

The length measured along the major axis is just over 1,100 feet while the width varies from about 700 feet at the narrowest point to just over 1,200 feet at the widest point— the communication with the lake. With the exception of the clay-bottomed submerged plunge pool previously mentioned the bottom consists of three elongate zones

(Map V). Each is of a somewhat different composition. These zones parallel each other and the longitudinal axis of the bay. The deepest part of the outer bay lies just inside the reef and varies from 21 to over 23 feet in depth. The bottom here consists mainly of angular fragments of dolomite of various sizes in a matrix of gravelly mud or silt. This rather unusual combination of sediments is apparently the result of the loosened fragments of dolomite on the top of the reef 71 being tumbled into the depths by storms and subsequently being inundated with silt dropping out of suspension during the relatively lengthy stretches of calm.

As one moves away from the base of the reef toward Gibraltar

Island the current along the bottom increases somewhat and the angular fragments give way to a water worn sandy gravel. Although the central zone has a distinctly different substrate the difference in depth between it and the zone Just described is slight, beingcn the order of one to two feet. The only submergent aquatic plants collected in the outer bay were taken either from this zone or the adjacent portions of the next and consisted of Valisneria americana in every case. It occurs in patches at depths at least as great as 18 feet. These patches are interspersed with areas which are apparently devoid of all rooted aquatics. As Gibraltar Island is approached from the bay the water becomes rapidly Shallow and the sediments coarser. At the foot of the cliff are found huge blocks of dolomite which have dropped into the bay after being undercut by wave action at the water line. The bottom between and beyond these larger blocks consists almost entirely of rounded rocks of dolomite with an occasional freshly dropped angular piece. No naiades or naiad shells were ever collected here* THE ORIGIN OF THE LAKE ERIE NAIAD FAUNA

It has been said that through a study of the past ve can best

interpret the present and better predict the future* Ball (1861),

Whiteaves (1861, 1863), and Walker (1895:13; 1898:12; 1900, 1913)

followed this principle in utilizing the historical physiography of the Great Lakes region in explaining the origin of the naiad fauna found there. Ortmann (1912, 1913, 1919, 192U) was also aware of the value of correlating changes in drainage systems with fauna! distri­ bution patterns. In this manner he was able to account for the dis­

continuous distribution of several species which are found in most of the Lake Erie tributaries but not in the lake itself. This work and

Walker's earlier studies in the field of naiad zoogeography have more recently been confirmed by Van der Schalie (1938, 19Ll, 19L5).

This last worker has also succeeded in using unusual distribution patterns to decipher former drainage patterns whose existence was not evident on the basis of physiographic evidence alone (Van der Schalie,

19U5)* It is of interest to note that geologists (Gilfillan, 1959:19) only recently have confirmed the existence of a low post-glacial stage of Lake Erie which Ortmann (192l|tll3) predicted on the basis of naiad zoogeography thirty-five years ago. Other predictions, seme listed below, still await confirmatory evidence from other fields*

The origin of the Lake Erie naiad fauna has, for the most part, been carefully mapped out by the workers mentioned. The movement

72 73

of the present lake fauna Into the drainage system it now occupies is

intimately related to and dependent upon the nature of the retreat

of the Wisconsin Glacier*

It is generally agreed that the pre-glacial fauna of the Great

Lakes region was extirpated with the advance of the Wisconsin ice

sheet. Adams (1902:308) simply states* "The original plant and animal

population of the northeastern United States was cleared avay by the

advance of the glacial ice. . ." Walker (1913:58) is more emphatic in

concluding "That the original pre-glacial fauna of the present St.

Lawrence system was absolutely exterminated during the glacial period* . . . ." It follows that any fauna in that region today is properly termed re-entrant and* if an aquatic form is in question*

that it moved into the glaciated area by means of a suitable drainage

system which was continuous from a non-glaciated preserve at some

time since the retreat of the Wisconsin ice. The mode of retreat of the ice from the Great Lakes area was originally worked out by a number of geologists (e.g.* Newberry* Winchell* Dryer, Hubbard*

Wright* etc.) participating in state survey work during the last quarter of the last century. Their work was brought together* organized* supplemented* and expanded by Leverett and Taylor (1915) in their monumental work— The Pleistocene of Indiana and Michigan and the

History of the Great Lakes. This series of events has recently been reworked in view of the evidence accumulated during nearly half a century of subsequent work and published in book form as the Geology of the Great Lakes (Hough* 1958). A review of this literature reveals 7 U

that the naiad zoogeography of the Great Lakes can be explained best

in a series of four to six chronological steps each of which is in

accordance with the known facts of glacial geology. A set of four

maps have been drawn to aid in such a presentation and while these

maps are in part original, the information upon which they are based

comes almost entirely from the above publications.

The retreat of the Erie lobe of the ice sheet resulted in out-

wash streams which flowed out and away from the glacier so long as

the ice margin extended south of the Ohio divide. When the ice had

retreated to the north of the divide meltwater lakes formed along its margin and these eventually flowed over the lowest part of the

terminal moraine which contained them. In the case of the Erie lobe

the meltwater lake has been named Lake Maumee, the moraine was the

Fort Wayne Moraine, and the outlet was at the site of the present city of Fort Wayne. The water 1 eaving Lake Maumee thus flowed across

Indiana, joined the Wabash River and continued on to join the lower

Ohio River (Map VIII).

While the nature of the Maumee-Wabash Outlet must have been variable, considering fluctuations in the melting rate characteristic of retreating glaciers, it seems certain that it maintained itself as a very large river for considerable periods of time. This is evidenced by the Invasion of Lake Maumee from the lower Ohio River by fish species which frequent only such rivers as the (M o , Mississippi, and the lower reaches of their largest tributaries. These fishes include the Sheepshead, Aplodinotus grunniens Rqfinesque; Sturgeon, Acipenser 75 fulvcscens Rafinesque; Paddlefi sh, Polyodon spatbula (Walbaum) ;

Spotted Gar, Lepisosteus productus (Cope), Bowfin, Amia calva Linnaeus,

Northern Shorthead Redhorse, Moxostomaoa aureolum (Le Sueur) and the

Mooneye, Hiodon tergisus Le Sueur* It is not surprising, then, that a number of large river naiades also made the migration, possibly as glochidia on the gills or fins of the host fish* The Sheepshead, famous as a bottom feeder, acts as host to several naiades including

Proptera alata (Say), Leptodea fragilis (Rafinesque), Truncilla donaciformis (Lea), and Leptodes laevissima (Lea) (Howard, 191!*:37)*

The first three species of this group are common forms in Fishery

Bay, as is the Sheepshead, while L. laevissima for some unknown reason is not known from Lake Erie. The results of this study indicate that the large river peruviana Lamarck form of Amblema plicata (Say) and the undata (Barnes) form of Fusconaia flava (Rafinesque) are also part of the present lake fauna.

Records of the Fusconaia subrotunda complex from Lake Erie

(Sterki, 1907:391) (Ortmann, 1909:203) (Walker, 1913*22) were later identified (Ortmann, 1919:11) as the superficially similar Plcurobema cor datum coccineum (Conrad)* The fact that the host fish of the F. subrotunda complex, the Skipjack Herring, Pomolobus chrysochloris

Rafinesque (Howard 19lU*19), has never been recorded from Lake Erie supports this conclusion* In view of the fact that the Skipjack is a fish of the swift, clear, deep waters of large rivers (Trautman, 1957:

179), it may have moved into glacial Lake Maumee, perhaps persisted in the Erie River which followed, but did not survive the transition to the relatively slow-moving turbid lake of today* 76

The (Opinion of most if not all previous students of Lake Erie naiad geography seems to be that the entire lake fauna was derived from the Mississippi Basin by way of Maumee-Wabash outlet of Lake

Maumee. It is my belief that they are correct with the exception of a single species, Llgumia nasuta (Say). This species has never been collected— alive, subfossil or fossil— from any stream of the

Mississippi drainage although its nearest relative Ligumia subrostrata

(Say) is found only in this system. L. nasuta is found in several

Michigan Lakes (Goodrich, 1932:108), Lake Huron, Lake St. Clair, and

Lake Erie (Goodrich and Van der Schalie, 1932), the lower reaches of several Lake Erie tributaries (Van der Schalie, 1938:61;), Lake

Ontario and the Erie Canal (Ortmann, 1919*275-6), New England

(Johnson, 1915*22), and streams flowing into the Atlantic south to

North Carolina (Simpson, 19lU*97)»

It is further reported from tributaries of a lake in Portage

County, Ohio (Dean, 1890:21), from "Muzzy Pond, near Rootstown, •* portage Co.," Ohio (Sterki, 1907:389) and from the upper Cuyahoga River

(Dean, 1890) (Ortmann, 1921;:110). These stream records from Portage

County are particularly unusual in view of the fact that this species is found elsewhere in quiet waters and, furthermore, that it is absent from all but the bay-like drowned mouths of the other Lake

Erie tributaries. I collected in the upper Cuyahoga in July, 1959, in order to determine if this species still persisted in those waters and, if so, to observe the microhabitat occupied. Several living specimens were taken along with a few empty shells. These few 77 individuals were taken from a firm sandy gravel bottom in a fast current. Except for the strength of the current, the physical habitat seemed not unlike those areas of Alligator Bar where this species is found in Fishery Bay. The host fish is as yet unknown and the presence of this naiad in the upper reaches of a single Lake Erie tributary remains unexplained.

Ortmann (1913*379) reasoned as follows concerning the origin of the distribution of L. nasuta:

Its western origin is confirmed by the fact that the only species allied to it, Eurynia subrostrata (Say), is western and is found in the central and western parts of the interior basin in large quiet rivers, ponds and lakes, avoiding rough water and strong current. For this reason, probably, it is not found in the upper Ohio drainage. This species has crossed somewhere in the region from northern Illinois to northern Ohio into the lake drainage, developed there into the species nasuta, which then spread eastward, following the quiet waters of the lakes and those of the canal till it reached the estuary of the Hudson. Thence it had no difficulty to spread farther over the Coastal Plain and reached across New Jersey, the lower Delaware, and even beyond. . . . Ve are thus to regard Eurynia nasuta as a quite recent immigrant in the Atlantic drainage, belonging surely to the Postglacial time, and this immigration might have been completed even by the help of modern, artificial canals.

It must be conceded that the above explanation is quite possible but, in view of the available evidence, it seems to be less probable than a second possibility outlined below. A piece of evidence should be added to the above which, although it seems to have little bearing on the problem at present, may be of value to future students. During archaeological excavations at the Fairport Harbor Village site near

Painesville, Lake County, Ohio, a number of naiad shells were found Maumee-Wabash Migration Route MAP VIII. LAKE MAUMEE, HIGH STAGE

Mowark-Hudson Migration Route MAP IX. THE CARY-PORT HURON, OR TWO CREEK, OR LAKE WAYNE STAGE 79

(Goslin, 19k3:5l)* The species L. nasuta was among those yet identi­

fiable, thus placing it in Lake Erie before the canal building era.

This would seem to rule out the possibility of a post-glacial east to

west migration of the species from the Atlantic coast. Evidence from

glacial geology, however, has established an eastward flowing outlet

of Lake Erie meltwater at some time (perhaps several times) following

earlier outlets to the west (Leverett and Taylor, 1915) (Martin, 1939:50,

52) (Hough, 1950: fig. 59 & 63)* The existence of such a migration

route (Map IX) would provide ready access to Lake Erie of any of the

fresh water fishes from the Mohawk or Hudson Rivers in the east. It

seems quite possible that the yellox* perch, Perea flavescene (Mitchell), may have entered the Great Lakes for the first time by such a route

since records (Trautman, 1957:553) limit its distribution in Ohio during the early eighteen hundreds to Lake Erie and small lakes in the northern part of the state. This original distribution sounds

interestingly enough like that of L. nasuta and, in fact, Trautman lists seven collection records of Perea flavescens for the upper

Cuyahoga. The distribution of L. nasuta along the Atlantic coast lies entirely within and all but duplicates that of P. flavescens. It would not be surprising to find that a parasite-host relationship exists between these two species in spite of the fact that the evidence is purely circumstantial. The presence of P. flavescens bones in the

Fairport Harbor material makes such a possibility seem even more likely. A migration path of the type described would also (1) eliminate the unlikely speciation of this form since the retreat of the 80

Wisconsin, (2) provide a non-glaciated preserve presently occupied by

this species in southern Pennsylvania, New Jersey, and other states

south to North Carolina, and (3) eliminate the unlikely movement of

this freshwater species from stream to stream down the east coast

from New York to North Carolina producing the discontinuous distribu-

tion found there today* While the available evidence favors this

latter theory, it is realized that the question is far from settled

and that some evidence to the contrary exists. It is, for example, a

curious fact that af all the east coast naiades not found in the

Mississippi Basin only L. nasuta is found in Lake Erie*

At a date later than the time of the original Mohawk-Hudson or

Susquehanna Outlet dealt with above the ice retreated from the

Niagara escarpment and from a large part of the Lake Ontario basin as well. This allowed a much lower outlet of Lake Erie by way of the

Niagara River into Lake Iroquois (Map X) (a predecessor of Lake

Ontario) (Martin, 1939*56^ (Hough, 1958*293) and a lower outlet of

Lake Iroquois which may have followed the Mohawk Valley rather than run parallel to it at a higher elevation somewhat to the south as previously. The Niagara Escarpment was much lower then than now due perhaps to the tremendous weight of the ice sheet. Lake Erie was apparently all but drained and transformed into a valley having only a remnant of its former bulk remaining as a small lake in the eastern basin (Walker, 1913*15) (Ortmann, 192U:113) (Van der Schalie, 1938*11)*

While the geological evidence concerning the lowest level reached is not conclusive, recent finds by Hartley and Verber (Qilfillan, 1959*19) «p A

Erie River Migration. Route,Trent- Vailey Migra t ion Route MAF X . KIRKFIELD STAGE OF HURON AND MICHIGAN BASINS EARLY ERIE STAGE

/\

MAP XI. DISTRIBUTION OF NAIAD FAUNAL GROUPS IN THE NORTHEASTERN UNITED STATES (modified from Van der Schalie, 1950) 82

place the old river channel which occupied this valley at 106 feet

below the present lake surface at Vermillion. Such a drop in lake

level would effectively drain the western and central basins of the

lake as predicted by Ortmann (192U). The river thus formed in the

Erie Valley by the confluence of the Maumee, Raisin, Huron, and

Clinton Rivers and receiving the Portage, Sandusky, Huron, Vermilion,

Cuyahoga, and others as tributaries might well be called the Erie

River in contrast with the pre-Wisconsin Erigan River which occupied

this same valley.

It seems certain that the Erie River was a stream of major

proportions since the large river fauna derived previously from the

lower Ohio has persisted in part into the present. The existence of

this river enabled several stream species of naiades to move down its

length from the Maumee and up into the various tributaries. As the

Niagara Escarpment slowly lifted, the lake refilled; this extinguish­

ing the strictly stream fauna as the valley once again became lake.

Three species of naiades are found today in the major lake tributaries

and not in the lake itself, thus demonstrating that in some as yet

unexplained manner some bodies of fresh water can present an effective

barrier to some fresh water animals. One of these naiad species,

Actinonaias carinata (Barnes), has been recorded from the Grand River

of Ontario, a northern tributary of the eastern basin (Robertson &

Blakeslee, 19U8:10U). This suggests the past existence of a contin­ uous stream environment of the former Erie River with the Grand River. 83

I doubt the existence of such an extreme low level because of the absence of the other two species, Lampsilis fasciola Rafinesque and

Alamidonta marginata Say, and because the photograph of Robertson and Blakeslee (l?U8:pl. 12, fig. 7) labeled "Actinonaias carinata

(Binney). Grand River, Ontario.n is most certainly a male specimen of the ventricosa form of Lampsilis ovata (Say)— a common lake species.

The Erie River phase of the retreat of the Wisconsin ice sheet was apparently accompanied by the Trent outlet from the upper Great

Lakes by way of the Georgian Bay Into Lake Iroquois (Hap X). This permitted the invasion of the Georgian Bay and ripper Lake Huron by several eastern naiad species (i.e., Lampsilis radiata (Gmelin) and

Elliptio conplanatus (Dillwyn) and resulted in the curious fact that these two species are found on either side of Lake Erie in the

St. Lawrence system and yet neither occurs in Lake Erie (Hap XI). Just what factors operate in preventing the movement of these species into southern Lake Huron, through Lake St. Clair, and the Detroit River into Lake Erie are unknown. SUPERFAMILY NAIADACEA MENKE

The pearly fresh water atussels are all classified as a single

group, the superfamily Naiadacea (or family Naiades of Lamarck) belong­

ing to the Order Eulamellibranchiata of the Class Pelecypoda. Although

there is some disagreement concerning the taxonomic levels that

should be given some of the larger grotq>s, the order of arrangement is

reasonably uniform among various authors*

The superfamily Naiadacea has been characterised (Dali, 1895):

Shell of varied form, normally equivalve, inequipartite, and dimyarian; rarely alate; shell substance nacreous and prismatic, with a conspicuous epidermis; hinge area obs­ cure or amphidetic; ligament parivincular, usually opistho- detic and external; pallial lobes usually free, except for an anal siphon, the pallial line simple; foot normally long, compressed, keeled; byssus obsolete; young usually with a distinct nepionic stage; station usually fluviatile or lacustrine.

The classification of the Naiadacea followed here is that of

Ortmann (1921:li5b) *

Superfamily Naiadacea I. Family Margaritanidae II* Family Unionidae 1* Subfamily Unioninae 2. Subfamily Anodontinae 3* Subfamily Lampsilinae III. Family Mutelidae 1. Subfamily Hyrlinae 2. Subfamily Mutelinae

The family Unionidae may be characterized: Post-branchial mantle lobes not fused between the branchial and cloacal cavities; 85

anterior margins of the inner gills not in contact with the labial

palps; mantle margins between anal and brachial apertures not ihsed;

stipra-anal aperture usually present; vater-tubes of the gills usually

formed by solid septa; both pairs or only the outer pair of gills

marsupial, never the inner pair only.

All the species of naiades recorded from Lake Erie follow the

above description.

The subfamilies of Unionidae were redefined by Ortmann (1911) and

these diagnoses should be carefully studied by anyone intending to do

systematic work with unionids. The group dealt with here is charac­

terized as follows:

Subfamily Unioninae (Swainson) Ortmann, 1911

Inner lamina of inner gills generally free from the ab­ dominal sac (sometimes, in extralimital forms connected); supra-anal opening sometimes not separated from the anal, normally present, the closed part rather short; branchial opening well-defined; no papillae or flaps on edge of mantle in front; marsupium formed by all four gills, or by the outer gills only; edge of marsupium always sharp and not distending; water-tubes not divided in the gravid female; glochidium semi-elliptic or semicircular, with­ out spine; shell generally heavy and solid, rounded to elongated, mostly with dull colored epidermis; sculpture of the beak generally rather indistinct, concentric, or pustulos, or with indications of double loops or zig-zag bars; hinge always complete, with rather strong teeth; generally no difference of sex shown in the shell (Ortmann, 1911:335).

Of the 28 species of naiades found in Fishery Bay, seven which belong to the Unioninae are treated below. This subfamily includes most of the heavy shelled highly ornamented species common to the riffles and fast water stretches of streams. Their presence in a lake environment is a matter of interest to students of ecology, zoo­ geography, systematics, and evolution. 86

FUSCONAIA FLAVA F1AVA (RAFINESQUE, 1820) (L. fuscus ■ duskyj naias = water-nymph) (L. flavus “ yellow) Figures 19, 10, & 11, page 87

Synonomy:

Obliquarla flava Rafinesque, 1820. Rafinesque (1820:305)• Unio rublginosus Lea, 1829. Lea (1829:1*27). Unlo flavus ^Rafinesque, 1820). Conrad (183U:69). Margarita rubiglnosa (Lea, 1829). Lea (1836:20). Unio rubfglnosa (Lea. 1829). Deshayes (1839:672). fiargaron rublginosus (Lea, 1829). Lea (l852r2U). Unio flavus rublginosus Lea, 1829. Paetel (1890:152). Quadrula rublginosa (Lea, 1829). Baker (1898:77). FUsconaja rubiglnosa (Lea, 1829). Ortmann (1912:2Ul). Fusconaia undata rublginosa (Lea, 1829). Ortmann (1913:291). Quadrula flava (Rafinesque, 1820). Vanatta (1915:557). Fusconaia flava (Rafinesque, 1820). Utterback (1915*108). Fusconaia fiava parvula Grier, 1918. Grier (1918:11), (in part). Fusconala flava parfUla Grier, 1918. Grier (1922:131), (in part). Quadrula flava parvula (Grier, 1918). Frierson (1927:55), in pari).

Type Locality:

". . . the small rivers falling into the Kentucky, Salt or Green rivers." (Poulson,1831:38).

Type Specimens:

Primary types never designated. Metatype (Rafinesque-Poulson type) A.N.S.P. 20230 (Vanatta, 1915:557).

Lake Erie Records:

1909 Quadrula rubiglnosa. Ortmann, p. 203.

Presque Isle Bay and Horseshoe Pond, Erie Co., Pa.

1910 Quadrula rublginosa. Gary, p. 183.

Cedar Point, Erie Co., Ohio

1912 Quadrula rubiglnosa. Clark & Wilson, p.; 38.

South Bass Island shore, Ottawa Co., Ohio. FUSCONAIA FLAVA FLAVA (RAFINESQUE, 1820) September 20, 1956 Length 44 am# Fishery Bay of Lake Erie Approx# Age 22 years Eeight 37 am# Put-in-Bey Twp., Ottawa Co#, Ohio o.s.u. 3025 Width 22 am# Figures 9. 10, 11

September 29, 1956 FLSffiOBSMA COBDATUM COCCINECM (CONRAD. 1836). Lemrth mm Approx# Age 23 years Fishery Bay of Lake Erie iw O.S.U. 3069 Putpin-Bay.Twp#, Ottawa Co., Ohio ¥ldfh Figures 12, 13, 14 * ® 88

1913 Quadrula rubiginosa. Walker, p. 22.

Lake Erie

1918 Risconaia flava parvula. Grier, p. 11.

Presque Isle Bay, Erie Co., Pa.

1919 Fusconaia flava parvula. Ortmann, p. 23.

Presque Isle Bay and Horseshoe Pone, Erie Co., Pa.

Crystal Beach, Welland Co., Ont., Can.

Port Rowan, Norfolk Co., Ont., Can.

Cedar Point, Sandusky Bay, Erie Co., Ohio

La Plaisance Bay, Monroe Co., Mich.

1920 Fusconaia flava parvula. Grier, p. 161, 162.

La Plaisance Bay, Monroe Co., Mich.

Cedar Point, Erie Co., Ohio

Vermilion, Erie Co., Ohio

Presque Isle Bay (and vicinity), Erie Co., Pa.

Buffalo, Erie Co., N.Y.

Port Colborne, Welland Co., N.Y.

Port Dover, Norfolk Co., Ont., Can.

Port Rowan, Norfolk Co., Ont., Can.

1930 Fuscohaia flava parvula. Ahlstrom, p. U7.

East Harbor, Erie Co., Ohio

Buckeye Is. and Rattlesnake Is., Ottawa Co., Ohio

1932 Fusconaia flava. Goodrich, p. 89.

Lake Eric 89

1932 Fusconaia flava parvula. Goodrich & van der Schalie,

p. 11.

Lake Erie

1937 Fusconaia flava parvula. LaRocque & Oughton, p. 152.

Lake Erie

1938 Fusconaia flava. Brown, Clark, & Gleissner, p. 687.

East Harbor, Erie Co., Ohio

Pelee Is., Essex Co., Ont., Can.

Fish Hatchery Bay, South Bass Is., Ottawa Co., Ohio

19h2 Fusconaia flava parvula. Shelford & Boesel, p. 181*.

Lake Erie, western

191*8 Fusconaia flava parvula. Robertson & Blakeslee, p.9h.

Niagara River at Cayuga Is., Niagara Co., N.Y.

Thunder Bay, Ont., Can.

Long Beach, Welland Co., Ont., Can.

191*8 Fusconaia flava. Robertson & Blakeslee, p. 93.

Niagara River near Black Creek, Welland Co., Ont., Can.

1953 FUsconaia flava parvula. LaRocque, p. 91.

Lake Erie, western part.

1953 Fusconaia flava. Wood, p. 58.

Lake Erie, western basin.

195U Fusconaia flava. Langlois, p. 15U.

Lake Erie, western end. 90

FUSCONAIA FLAVA UNDATA (BARNES, 1823) (L. fuscus ** dusky; naia ■ naiad) (L. flavus * yellow) (L. unda ■ wave; atus ■ possessing) Figure I& page 91

Sjynonomy*

Unio undatus Barnes, 1823. Barnes (1823*121). Mya undata Barnes, 1823. Eaton (1826:219)* Onio trigonus Lea, 1831. Lea (1831:110). Margarita oblique (Lamarck, 1819).* Lea (1836:20).** Margaron trigohus (Lea, 1831). Lea (1802:30). Margaron Obliquus (Lamarck, 1819). Lea (1802:20). Unio triangularis Say, 183U.*** Kuster (1802:£6). Unio pilaris Lea,' 18U0. Reeve (l865:f. 138). Quadrula irigona (Lea, 1831). Baker (1898*76). Quadrula obliqua (Lamarck, 1819) (in part). Sinqpson (1900:788). Quadrula undata (Barnes, 1823). Walker (1910*21*). Fusconaja undata (Barnes, 1823)* Ortmann (1912:21*1)* Fusconaia undata! (Barnes, 1823)* Utterback (1910:101*). Fusconaia undata trigona (Lea, 1831). Utterback (1910*106). Fusconaia undata trigonoides Frierson, 1913. (?) Utterback (1910:107). Fusconaia undata wagneri Baker, 1928. Baker (1928*61*).

Type Locality:

"Oiiisconsin and Fax Rivers" (Barnes, 1823*121).

Type Specimens:

Topotypes from the Wisconsin River, Unv. Illinois 201*83 (Baker, 1928*1*61*).

*U. obliqua Lam., 1819 is unidentifiable (Ortmann & Walker, 1922s 21).

**I find no listing of trigonus Lea, 1831 in Lea's I836 synopsis. A defense of the form is given in a footnote (p. 20) and Simpson (1911** 881) refers to its listing in Lea's synopsis on page 18. It is not so listed there or anywhere in my copy of Lea's work nor in the O.S.U. copy.

***is actually Obovaria olivaria (Raf., 1820). Large River Specimen

Form undata

Lake Erie Specimen

Form undata

Small Stream Specimen

Form flava

CM.

Figure 15. Forme of Fuaconaia flava (Rafineeque). (Photography "by George fhlnney)

91 92

Lake Erie Records:

1895 Unio trigona. Marshall, p. 93.

Lake Erie.

1909 Quadrula trigona. Ortmann, p. 203.

Presque Isle Bay and Horsehoe Pond, Erie Co., Pa.

1910 Quadrula undata. Walker, p. 22.

Buffalo, Erie Co., N.Y.

Port Dover, Norfolk Co., Ont., Canada.

1912 Fusconaia undata. Ortmann, p. 21*1.

Lake Erie

1913 Quadrula undata (?). Walker, p. S.

Lake Erie

1932 Fusconaia undata. Goodrich & van der Schalie, p. 12.

Detroit River.

Many of the records cited under F. f. flava undoubtedly contained specimens of F. f. undata. Only those records were included in the above list which made reference to undata Barnes or its synonym trigona Lea and some of these may include specimens of F. f» flava as well as intergrades. It would be convenient, and perhaps for most purposes justifiable, to refer to this complex in Lake Erie as simply

Fusconaia flava. It should be kept in mind, however, that the evi­ dence indicates the existence of genetic as well as environmental differences between the extremes and in most places outside Lake Erie these forms exivt as relatively homogeneous populations of one or the other or some intermediate form. 93

Fishery Bay Records: Collection Cat*- No* Date Form Site Collector

OSU 327 IX:10:195U flava (Raf*) Outer Bay D.H.S.

Q5U 128^ IX:21:195U flava (Raf.) Inner Bay D.H.S.

OSU 11U3 X:23:195U flava (Raf.) Inner Bay D.H.S.

OSU 1129 X:23:195U undata (Bar.) Outer Bay D.H.S.

OSU 2952 Summer 1956 flava (Raf.) Bay W.C. Coil

OSU 302li IX:20:1956 flava (Raf.) Outer Bay D.H.S.

osu 3025 IX:20:1956 flava (Raf.) Outer Bay D.H.S.

osu 3071 IX:20:1956 flava (Raf.) Inner Bay D.H.S.

Shell Characteristics:

Size small to medium; subinflated to inflated; outline subtri- agonal to subquadrate, some older larger specimens becoming elongate rnomboidal; dorsal margin scarcely but perceptdbly curved as is the posterior margin, ventral margin straight or slightly emarginate just enterior to the posterior ridge and making an angle of 90° or less vith the posterior margin, ventral margin evenly and fully rounded into a rather short straight anterior margin which abruptly recurves and terminates at the level of the lunule; distinctly anteriorly inequi- partite to nearly equipartite, umbones moderately high, rising above but rarely meeting over the hinge line; beak sculpture of 3-6 angular concentric bars forming a series of acute angles on the anterio- lateral surface and a heavier series of nearly obtuse angles on the posterior ridge, the outermost of the latter being represented by 9h

nodular undulations along the ridge while the entire innermost bars

are present as miniattire concentric trapezoids; posterior ridge well

defined and subtending a relatively vide very shallow lateral sulcus;

shell subsolid to solid, periostracum and ligament bright yellow in

very young (0-15 nm.) individuals, both becoming brown or blackish

brown in adults; growth lines narrow, dark, distinct, and regular;

rays usually absent, when present limited to region of sulcus, fine,

gray-green, and inconspicuous; lunule well developed, as long or

longer than wide.

Nacre white to cream with some iridescence along the posterior

and posterio-ventral margim; pseudocardinal single in the right valve,

triangulate, serrate, and separated from the hinge-line and inter-

dentum by a sulcus, occasionally supplemented with a low lamellar

denticle on the hinge line immediately beneath the lunule and rarely by

a similar denticular swelling on the inner anterior margin of the

interdentum; right lateral usually single, scarcely curved, obliquely

striate above and below, abruptly terminating above the posterior

adductor cicatrix, occasionally accompanied by a very low super­ numerary lateral along its ventral base; interdentum narrowly oblique;

left pseudocardinals double, separated by a sulcus, subtending the

lunule or nearly so, anterior tooth narrowly triangulate to lamellar, nearly parallel to the hinge line; posterior triangulate, bordering a well developed, equilateral interdentum; laterals double, scarcely

curved, markedly obliquely striate within, terminating above the posterior adductor cicatrix; anterior cicatrices moderately impressed 9$

and distinct as are the posterior scars, posterior retractor cicatrix

inmediately beneath terminus of ventral lateral; dorsal suspensory

scars on the ventral surface of the interdentum in both valves;

pallial line distinct, lying veil within and parallel to the margin

throughout; umbonal cavity moderately deep*

Habitat (Map XII)

The seven specimens assigned to F. f. flava (Raf.) were all

taken from a firm, nonshifting sand or sand-gravel bottom. The single

specimen taken by diving was found completely burried in the sub­

strate with only the siphons showing. A slight irregular motion of

the water resulted in the closing of the valves and the disappearance

of the naiad. It may well be that a number of specimens were missed

in this manner. The pattern of shell erosion on those mussels taken by dredge suggest that most were taken from a similar situation. One

specimen, however, was so extensively eroded it could not be used in the age-length study. It was taken from a bottom of organic debris

in the deeper part of the inner bay and the erosion pattern sug­ gested that over half of the shell had extended above the protective portion of the substrate. This was the largest specimen collected and its relatively great weight in combination with the crowded annuli covering nearly half the disc indicate a very old age. A count of the non-eroded annuli, added to an estimate for the remainder of the shell, place it in the 1(0 plus year group. 96

TABLE 10. SUMMARY OF DIMENSIONAL AND PROPORTIONAL DATA OF SHELL MORPHOLOGY OF FUSCONAIA FLAVA (RAFINESQUE)

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index Minimum 11 8 73 k U8 Mean 1*1 33 79 21 51 Maximum 68 5U 8U 3U 61 Range 57 U6 11 30 13

Number of specimens ** 8

TABLE 11. DIMENSIONAL AND PROPORTIONAL DATA OF FUSCONAIA FLAVA (RAFINESQUE) RELATED TO LENGTH (SIZE) GROUP

Length Number Mean Mean Mean Mean Mean Group of Length Height Height Width Widtl (mm.) Specimens (mm.) (mm.) Index (mm.) Indo

0-9 0 — -- — — —

10-19 2 12 9 7h 5 5o

20-29 0 — — — ——

30-39 1 38 31 82 23 61

U0-L9 3 1*7 38 81 23 U9

50-59 0 -- — — ——

60-69 2 6U 50 77 33 51 LAKE ERIE

HUNDRED FEET Pooch Point

GIBRALTAR ISLAND

SOUTH BASS ISLAND Oak Point

Map XII* Distribution Records of Fusconaia f« flava (Rafinesque), Pugconala flava undata (Barnes)

• Fusconaia flava flava (Rafinesque).

© Fusconaia flava undata (Barnes)*

O Pleurobema cordatua coccineun (Conrad)•

vo •> 3 98

A single specimen taken from the peculiar rocky-silt bottom

just inside the Peach Point Reef is here assigned to F. f . undata

(Barnes) (see Remarks). It was taken with Pleurobema cordatum coc-

cineum (Con.), it being another of the relatively few species of

naiades found to inhabit this area. The degree of erosion in this

silty submerged trench is much less than one might expect and is

generally restricted to within the first two or three annuli of the

urabones. Naiades of the same age in the silt bottom habitats of the

shallower water of the inner bay usually have one-third to one-half

of the periostracum gone. A rather firm bottom of very fine sediments,

rich in finely divided organic debris, seems to be associated with

shell erosion and slow growth in Lake Erie while the non-shifting

sand-gravel bottom is associated with a more rapid growth accompanied

by little erosion.

Growth and Longevity

This species in Lake Erie has a relatively slow growth rate and

is rather long-lived. Neither the growth rate nor the longevity of

F. flava seem to have been studied for stream specimens and the only previous work on lake material is that of Grier (1922s 13b)* All of

Grier's specimens came from Lake Erie and most from Presque Isle Bay,

Erie County, Pennsylvania (qp. cit.:131). A recalculation of the data presented by Grier is included below for purposes of comparison.

These specimens showed a rate of 6.6 mm. yr. for the first five years of growth and 3*8 mm. yr. for the second five year growth 99

TABLE 12. AGE-LENGTH RELATIONSHIP OF FUSCONAIA FLAVA (RAF.)

Inner Bay Outer Bay Number Number Annulus Measure- Length (mm.) Annulus Measure- Length (mm.) Number meats Min. Mean Max. ®fa*iker raents kin. Mean Max. 1 2 5 7 8 1 0 mm m 2 1 - 9 _ 2 3 8 9 9 3 2 13 lk ia 3 a 11 12 13 k 1 «• 20 — a a 13 15 17 5 1 - 26 • 5 a 16 17 21 6 1 mm 29 mm 6 a 17 21 2a 7 1 - 32 - 7 a 18 2a 28 8 1 - 33 tm 8 a 19 26 30 9 1 - 3h - 9 a 20 28 32 10 1 - 37 mm 10 a 23 30 3a 11 mm 38 - 11 a 2a 31 35 12 1 - 39 - 12 a 25 32 36 13 1 - UO - 13 a 26 33 37 1U 1 - U1 mm ia a 27 3a 39 15 1 - U2 — 15 a 28 35 ao 16 1 - k3 - 16 a 29 37 a2 17 1 - aii - 17 a 30 38 a3 18 1 - a5 - 18 a 31 39 aa 19 1 - U6 - 19 a 32 ao a5 20 1 - U7 - 20 a 33 a i a6 21 1 - U8 - 21 3 aa a2 a7 22 - U9 - 22 2 35 ao a5 23 1 - U9> 23 2 36 a i k6 2U 1 - 50 • 2a i - 37 - 25 1 - 51 - 26 1 - 52 - 27 1 - 53 - 28 1 - 5U - 29 1 - 56 - 30 1 - 57 - 31 1 - 59 - AVERAGE LENGTH IN MILLIMETERS 40 0 6 20 0 Graph I*Graph 4 .Age-Length .Age-Length 8 Relationship of Pusconaia flava (Rafinesque)* flava of Pusconaia Relationship 12 ESTIMATED AGE IN YEARS YEARS IN AGE ESTIMATED 16 20 24 UER BA'OUTER 28 32 INNER BAY 36

0 4 100 101

period and exceed those for both the inner and outer bay specimens

during the same growth periods*

Growth Rate (mm./yr.) 0-5 6-10 11-20 Maximum Growth Period yrs. yrs. yrs. Age

Inner Bay 5.2 2.2 1.0 31

Outer Bay 3.8 2.2 1.0 21*

Grier (1922:1310* 6.6 3.8 — 12

Coker et al. (192TT15?) 7.9 (pond-reared F. f. undata)

^Recalculated data

Brown, et al. (1938) found that other species grew more rapidly

along the mainland shore and the above comparison with Grier's results

supports this observation. Shore waters are shallower, usually have

faster currents than the deeps, and are generally more productive.

These factors alone could be responsible for the difference in growth

rate and, if so, those naiades from the deep, quiet, muck bottoms of

the lake, far from the shore, should exhibit the slowest growth

rates. This relationship is observed in comparing the rate for the

inner bay, 5*2 mm./ yr. with the rate for the outer bay, 3.8 mm./yr., both rates representing the same growth period.

The older individuals are not only found to be slower growing but the effects of "compensatory growth" are seen in the identical rates attained by older individuals from the two habitats compared* 102

The age of sexual maturation is not known for this species.

In naiades of the subfamilies Anodontinae and LampsiHnae the age of

maturation is usually reflected by a rather sharp inflection in the

growth curve. This is particularly true in the case of the females

of those species having sexual dimorphism. Vhile there is frequently more than the suggestion of an inflection in individual growth curves

of specimens of Unioninae, the age at which it occurs is so variable

and its magnitude so slight that it is usually obscured when mean

lengths for each age are computed from a set of specimens. An exam­

ination of a number of individuals from the open lake as well as the bay suggests that the age of maturation of F. flava lies between five

and eight years. This estimate of range is based solely upon a study

of annular ring periodicity and should be subjected to the test of direct evidence when such becomes available. Considering that this

species is not particularly common in the lake and that it is a tachytictic breeder, it may be some time before the necessary material

can be accumulated. Every opportunity should be taken to obtain properly labeled alcoholic specimens of this species from the lake during every month of the year and particularly during the apparent breeding season from May through August (Ortmann, 1912:2Ul).

Although the "Pig-toe" of the dammer's does not attain the greatest age among the lake-dwelling naiades, it is definitely one of the longest living species of the region. The oldest specimen taken in Fishery Bay lias an estimated age of 31 years and, comparing this with other closely related species of the area, it would not be sur­ prising to find that some individuals live UO years or more. It seems 103 that in general* the slower an individual naiad grows, the longer it lives. It follows that the oldest specimens should be taken from the deep lake muck where growth is slowest. This relationship would probably hold true for this environmental extreme were it not for the rapid rate of shelf corrosion which occurs in such circumstances.

It appears that there is an accumulation of some acid (perhaps carbonic) at the mud-water interphase and this acid (?) rapidly corrodes the shell from beneath the periostracum once it has gained access. The majority of dead shells dredged from such habitats have holes corroded all the way through in the region of the umbones.

The optimum habitat niche for the lake naiad, assuming old age to be desirable, would be the deep water sand-gravel bottoms where the eroding action of the sediments appears to be far less destructive than the corrosive action of quieter waters.

Remarks

There are Lake Erie records for both Fusconaia flava (Raf.) and Fasconaia undata (Barnes)9 those for the ecoform parvula Grier having been generally assigned to the former. Since many of the Lake

Erie fusconaia seemed to resemble F. undata much more closely than

F. flava an attempt was made to determine just what (form(s) of this complex exists in western Lake Erie. The original descriptions of each form described in this complex from this general area were consulted. In each case the characteristics were recorded and compared ioU and the dimensions of the holotype taken from the description or, that lacking, from the accompanying figure. Despite the listing of other distinguishing characteristics the only ones which seem to hold for the material available are those of proportions.

The described forms may be arranged in a linear series in which the width index increases from 29 in the highly compressed form flava described by Rafinesque (1820) from small tributaries of the

Kentucky, Salt, or Green Rivers to an index of 75 in the greatly inflated form wagneri described by Baker (1928:61*) from the Lake Pepin expansion of the Mississippi River. These figures were then compared with the means and ranges of a group of 83 Fusconaia from many localities in western Lake Erie. This series contains all the Lake

Erie Fusconaia specimens in the collection and Includes individuals from almost every type of naiad habitat available in the western basin.

Length Height Height Width Width Form (mm.) (mm.) Index (mm.) Index

flava Raf., 1820 102 7U 73 30 29

rubiginosa Lea, 1829 73 52 72 31 13

parvula Grier, 1918 36 28 78 19 53

trigonus Lea, 1831 60 50 83 38 63

undatus Barnes, 1823 50 U6 92 3U 67

wagnerI Baker, 1928 58 56 98 U3 75 105

Specimens of Fusconaia sp. from Western Basin of Lake Erie

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index

83 individuals

Minimum 11 8 73 1* 1*3

Mean 1*5 36 80 23 51

Maximum 68 51* 88 3l* 61

The above series of holotype proportions indicates that these forms may be representative from various points along the morphological cline of a single species and, with the exception of the ecoform parvula they are found to intergrade in the indicated order in nature*

The form flava Rafinesque is characteristic of small headwater streams while the form wagneri Baker is found at the opposite extreme in a ponded portion of the Mississippi River known as Lake Pepin. If it were certain that each of these morphological forms was due to a dif­ ferent environment acting on the same genotype, then all these forms could be placed under a single specific name and the matter settled.

There are instances, however, when several forms may be found in the same area under apparently identical environmental conditions. There has never been a case, so far as I have been able to learn, where extreme forms have been found together so the differences noted may have been due to unobserved differences between microhabitats.

Since there exist two well-defined extremes connected by a series of intergrades it is best at this time to place all of the described forms in a single species and to designate the two extremes 106

as subspecies. The form flava Rafinesque, 1820, has priority as the

species name and used as a sub specific designation refers to the com­

pressed, relatively elongate form with low umbones. The form undatus

Barnes, 1823 is the second oldest name and was originally applied to

the inflated, relatively short form with high umbones. If relative

width be used to separate these subspecies, the rather arbitrary line

should probably be drawn halfway between the extremes of 29 and 75.

Such a procedure places all those specimens having a width index

below 52 into the F. f. flava group and those above 52 in the F. f.

undata group. If it should be found that these forms are purely

environmental the trinomials may be dropped. On the other hand,

if it should be demonstrated that sibling species are being dealt with the names may be restored to specific rank. It is my opinion

that the most important consideration be that the current classifi­

cation reflect current knowledge. This classification is as follows:

Fusconaia flava flava (Rafinesque, 1820). fibliquari a £ lava Rafinesque, 1820. Unio rubTginosus Lea, 1829. FVrsconaia flava parvula Grier, 1918 (in part). Fusconaia /lava undata (Barnes, 1823). Unio undatus Barnes, 1823. Unio trigonus Lea, 1831. Fusconaia flava parvula Grier, 1818 (in part). Fusconaia undata wagneri Baker, 1928.

An examination of the 83 Lake Erie specimens at hand reveals that 32 individuals are F. f. undata and 51 individuals are F. f. flava. None of these specimens fall under the extreme form flava or form wagneri dimensions given above. It is not surprising that Lake

Erie specimens are mostly intermediates if the above interpretation of 107 data is correct. Lake Erie has in the past been open to invasion by both forms and the environment today, while apparently not optimal for either subspecies, is nevertheless of a type which will support small populations of both headwater species and large river species side by side. I know of no other place where Carunculina parva

(Barnes), Villosa iris (Lea), Dysnomia triquetra (Rafinesque), and

Pleurobema cardatum coccineum (Conrad) may be found living within a few yards of such species as Proptera alata (Say), Leptodea fragilis

(Rafinesque), Truncilla donaciformia (Lea), and Obliquaria reflexa.

The fact that F. f. flava and F. f. undata intergrade almost completely in Lake Erie is further evidence of the lack of effective repro­ ductive isolation between these forms and substantiates their treatment here as members of the same species« 1 0 8

AMBLEMA PLICATA PLICATA (SAY, 1817) (Gr. amblys - blunt) (L. plicatus ■ folded) Fig. 16, p. 109

Synonomy

Unio plicata Say, 1817. Say (I8l7:pl. Ill, fig. 1). Unio rarlpiicata Lamarck, 1819. Lamarck (1819:71). Amblema costata Rafinesque, 1820. Rafinesque (1820:315). l)nio undulatus Barnes, 1823. Barnes (1823:120). Hya undulata (Barnes, 1823). Eaton (1826: ). Unio undulata (Barnes, 1823). Valenciennes (1833*229). Unio costatus (Rafinesque, 1820). Conrad (1836:17). kargarlta undulatus (Barnes, 1823). Lea (1836:12). Unio hippopaeus Lea, 18U5. Lea (181:5:163) (in part). l/riio latecostata Lea, 18U5. Lea (181:5:163). Margaron undulatus (Barnes, 1823). Lea (1852:20), Margaron hippopaeus (Lea, 181:5). Lea (1852:21). Margaron laticostasus (Lea, 181:5). Lea (1852:21). Pleetomerus costatus (Rafinesque, 1820). Conrad (1853:260). Margaron~Iaticostatus (Lea, 181:5). Lea (1870:31). tlnio pilsbryi Marsh, 1891. Marsh (1891:1). Quadrula undulata (Barnes, 1823). Baker (1898:82), Quadrula undulata latecostata (Lea, 181:5). Simpson (1900:769). Quadrula undulata pilsbryiTMareh, 1891). Simpson (1900:769). Quadrula undulata hippopaea (Lea, 181:5). Ortmann (1909:203), Crenodonta undulata (Barnes', 1823). Ortmann (1912:21:6). Crenodonta plica ta"(Say, 1817). Ortmann (1912:21:6) (in part), Quadrula hippopaea (Lea, 181:5). Walker (1913:5) (in part). Amblema plicata costata Rafinesque, 1820. Ortmann (1919:28). Amblema plicata (.Say, 1817). Ortmann (1919:25) (in part). Amblema costata eriganensis Grier, 1920. Grier (1920:17) (in part). Amblema plicata hippopaea (Lea, 181:5). Frierson (1927:61) fin" part). Crenodonta costata (Rafinesque, 1820). Clench (1959:111:0).

Type Locality:

"Lake Erie" (Ortmann & Walker, 1922:13).

Type Specimens:

The holotype is not known to exist. All specimens from Lake

Erie are topotypes, but which form, i.e., costata Rafinesque or peruviana Lamarck, was the holotype is not known. It may well have 109

AMBLEMA PLIOATA (SAY, 1817)* August 8 , 1954 Fishery Bay of Lake Erie Length 74 Approx. Age 18 years Put—in-Bay Twp*» Height 48 bub* OSU 298 Ottawa Co*, Ohio rfldth 36 mm* Figure 16

Tff.T.TPTTO DILATATP3 (RAF INIS CJIE, 1820) July 8 , 1955 Fishery Bay of Lake Erie Length 75 Approx. Age 14 years Put-ln-Bay Twp., Eelf^it 40 mm. OSU 1628 Ottawa Co*, Ohio Width 25 mm. ' Figure 17 1 1 0

been an intermediate between the two extremes. The above synonomy of

A. £• plicata and the following one for A. £. peruviana are constructed

on the supposition that Say had in hand a lake form of what has been

generally known as costata Rafinesque. It is to this form that the

Lake Erie specimens have most frequently been assigned. A careful

search for the holotype of plicatus Say, 1817, and study of the

original description should be made. If this described form is un­

identifiable the next available name for the species would be

peruviana Lamarck, 1819, with costata Rafinesque 1820 as the headwaters

subspecies. In any event, Lake Erie has both forms and many inter­ mediates, thus demonstrating that we are dealing with a single

species*

Lake Erie Records:

1817 Unio plicatus. Say, pi. Ill, fig. 1 (no pagination)

Lake Erie

18U5 Unio hippopaeus. Lea, p. 163*

Lake Erie*

1895 Unio undulatus. Whiteaves*

Detroit River at Windsor, Essex Co., Ont., Canada

Port Colbourne, Welland Co*, Ont., Canada

1895 Unio undulatus. Kirsch, p. 332,

Port Clinton, Ottawa Co*, Ohio

1895 Unio undulatus. Marshall, p. 50.

Buffalo, Erie Co., N.Y* Ill

I898 Unio hippopaeus* Walker, p. *>•

Lake Erie

Detroit River

1909 Quadrula undulata hippopaea. Ortmann, p. 203.

Lake Erie ! | 1910 Quadrula undulata. Gary, p. 183.

Cedar Point, Erie Co., Ohio |

1912 Crenodonta plicata. Ortmann, p. 21*6.

Pennsylvania shores

Ohio shores

1912 Quadrula undulata. Clark & Wilson, p. 38.

South Bass Is., Ottawa Co., Ohio

1913 Quadrula hippopaea. Walker, p. 22.

Lake Erie

1919 Amblema plicata. Ortmann, p. 27.

Presque Isle Bay, Erie Co., Pa.

Cedar Point, Erie Co., Ohio

Sandusky Bay, Erie Co., Ohio

La Plaisance Bay, Monroe Co., Mich.

Maumee Bay, Lucas Co., Ohio (p. 30).

1920 (c) Amblema plicata. Grier, p. 1^1.

Lake Erie

1920 (b) Amblema plicata. Grier, p. 213.

Lake Erie

1920 (a) Amblema costata eriganensis, Grier, p. 17

Presque Isle Bay, Erie Co., Pa. 1 1 2

1922 Amblema plicata. Grier, p. 131.

Presque Isle Bay, Erie Co., Pa.

La Plaisance Bay, Monroe Co., Mich.

Cedar Point, Erie Co., Ohio

192U Amblema plicata. Ortmann, p. 106.

Lake Erie

1930 Amblema plicata. Ahlstrom, p. 1*7*

East Harbor, Ottawa Co., Ohio

1932 Amblema costata plicata. Goodrich & van der Schalie, p. 11.

Lake Erie

1932 Amblema costata Goodrich, p. 87.

Great Lakes

1937 Amblema plicata. LaRocque & Oughton, p. 152.

Amblema costata. LaRocque & Oughton, p. 1*>2,

Lake Erie

Detroit River

Niagara River

1938 Amblema costata. Brown, Clark, & Gleissner, p. 687.

Pelee Is., Essex Co., Ont., Canada.

Fish Hatchery Bay, So. Bass Is., Ottawa Co., Ohio

East Harbor, Ottawa Co., Ohio

191*1 Amblema costata plicata. van der Schalie, p.

Lake Erie

19U2 Amblema costata. Shelford & Boesel, p. 182*

Western Lake Erie 113

1953 Amblema costata. Wood, p. 56.

"near Middle Sister Is."

"7 mi lev/ east of Pelee Is."

1953 Amblema costata. LaRocque, p. 86.

Amblema plicata. LaRocque, p. 87.

Amblema plicata hippopaea. LaRocque, p. 87.

Lake Erie

Detroit River

Niagara River

195U Amblema costata. Langlois, p. 153*

Western end of Lake Eric 1 1 U

AMBLEMA PLICATA PERUVIANA (LAMARCK, 1819). (Gr. amblys * blunt) (L. plicatus = folded) ("of Peru") Figure 18, page 11$

Synonomy

Unio peruviana Lamarck, 1819. Lamarck (1819:71). Unio plicatus (Say, 1817). Barnes (1823:120). Unio crassus (Barnes, 1823). Barnes (1823:118). Mya plicata (Say, 1817). Eaton (1826:219). Margarita plicatus (Say, 1817). Lea (1836:12). Unio gigainteus Lea, 1838. Lea (1838:35)* Unio plicataTSay, 1817)• Swainson (181+0:271). Unio hippopaeus Lea, 181+5 . Lea (181+5 :163) (in part). Margaron plicatus (Say, 1817). Lea (1852:20). Plectomerus plicatus (Say, 1817)* Conrad (1853:261). Unio heros Say, 1029. Kuster (1856:136). Quadrula plicata (Lesueur, 1817). Baker (1898:80). Quadrula plicata hippopaea (Lea, 181+5)* Simpson (1900:767). Crenodonta plicata (Say, 1817). Ortmann (1912:21+6) (in part). Quadruia~hippopaea (Lea, 181+5)* Walker (1913:5) (in part). Amblema peruviana (Lamarck, 1819). Utterback (1915:115). Amblema plicata TSay, 1817)* Ortmann (1919:25) (in part). Amblema costata eriganensis Grier, 1920. Grier (1920:17) (in part). Amblema plicata hippopaea (Lea, 181+5). Frierson (1927:61) (in part).

Type Locality

The locality of the holotype is given as Peru. This is an error (Ortmann & Walker, 1922:13), the form being limited to the

United States and Canada.

Type Specimens

Holotype, Museum of Paris? (Lea, l8£2:xi).

Lake Erie Records

1823 Unio crassus (k). Barnes, p. 118.

Lake Erie 115

Large River Specimen

Form peruviana

Lake Erie Specimen

Form peruviana

Small Stream Specimen

Form plicata

Figure 18. Forms of Amblema plicata (Say). (Photography by George Phinney) 1 1 $

1838 Unio plicatus. Kirtland, p. 198.

Lake Erie

1861 Unio plicatus. Whiteaves, p. ii58.

Welland Canal, Welland Co., Ont., Canada

1900 Unio piicata hlppopaea. Simpson, p. 767.

Lake Erie

1905 Quadrula plicata hlppopaea. Letson, p. 93*

Lake Erie, N. Y.

1905 Quadrula plicata hippopaea. Dali, p. 133*

Lake Erie

1907 Quadrula plicata hippopaea. Sterki, p. 390.

Lake Erie.

1910 Quadrula plicata. Gary, p. 183*

Cedar Point, Erie Co., Ohio.

It is impossible to say how many of the Lake Erie records here

listed for A. p. plicata and its syponyms include specimens of A. £.

peruviana. Only those records have been included under A. p. peruviana

above which refer to specimens taken from Lake Erie during that period

of time when the head water form was known as undulata Barnes and the large river form as plicata Say. 117

Fishery Bay Records:

Collection Cat* No* Date Form Site Collector

OSU 296 Vnir8:195U plicata (Say) Inner Bay D.H.S.

OSU 297 VIII:8:195b peruviana (Lam.) Inner Bay D.H.S.

OSU 298 VIII:8:195lt peruviana (Lam.) Inner Bay D.H.S.

OSU 299 1/111:8:195U peruviana (Lam.) Inner Bay D.H.S.

OSU 662 IX:21:195U peruviana (Lam.) Inner Bay D.H.S.

OSU 663 3X:21:195U plicata (Say) Inner Bay D.H.S.

OSU 66k IX: 21:1951: peruviana (Lam.) Inner Bay D.H.S.

OSU 1298 IX:21:195U peruviana (Lam.) Inner Bay D.H.S.

OSU llUl X: 23:1951: peruviana (Lam.) Inner Bay D.H.S.

OSU 1576 111:22:1955 peruviana (Lam.) Terwillegar's Pond D.H.S.

OSU 301U IX:20:1956 plicata (Say) Outer Bay D.H.S. osu 3015 IX:20:1956 plicata (Say) Outer Bay D.H.S. OSU 3016 IX:20:1956 plicata (Say) Outer Bay D.H.S.

OSU 3086 IX:20:1956 plicata (Say) Inner Bay D.H.S.

OSU 3087 IX:20:1956 peruviana (Lam.) Inner Bay D.H.S.

OSU 3088 IX:20:1956 plicata (Say) Inner Bay D.H.S.

Shell Characteristics

Size medium; subinflated; outline subquadrate in young, usually becoming somewhat elongate rhomboidal with age; dorsal margin nearly straight forming a gently curved but definite angle with the straight or slightly curved posterior margin; evenly rounded ventral margin 1 1 8

joined to the posterior by a curved angle which usually becomes more

acute with age; ventral margin continuous with anterior margin whose

curvature increases to the anterior extremity of the shell where it tends to become straight and terminates at the level of, but somewhat

anterior to, the lunulej distinctly anteriorly inequipartite, the beaks of the umbones occasionally approximating the anterior margin, umbones directed forward and moderately to rather fully inflated; beak sculpture a series of li-6 v-shaped nodules on the posterior slope which are sharply recurved posteriorly and irregularly connected on the lateral surface with corresponding curved bars which become obsolete as they curve medially toward the anterior lunule, inntermost one or two bars smoothly curved resembling concentric ellipsoids; posterior ridge broadly rounded and poorly defined forming little or no sulcus with the dorsal margin, lateral stir face of the disc below the posterior ridge with 0-6, usually 5, ridges which parallel the greatest length of the shell and are restricted to the posterior two- thirds of the surface, these ridges very rarely accompanied by a smaller oblique set which curve dorsally and posteriorly from the posterior ridge, becoming indistinct as they approach the dorsal margin of the low wing; shell subsolid to solid; periostracum light olivaceous in young specimens passing through light and dark brown to near black with age; growth lines narrow, dark, exceptionally distinct and regular; rays absent; ligament exposed, moderately heavy, brown to black; lunule elongate cordate, occasionally as wide as long. 119

Nacre white becoming bluish, iridescent posteriorly; pseudo­

cardinal single, triangulate, coarsely serrate in the right valve, flanked on either side by sulci which sometimes coalesce between the

tooth and the dorsal margin, a supplementary denticle occasionally develops on the hinge line adjacent to the lunule; right lateral

single, nearly straight, striate above and below, rarely with a low supplemental abruptly terminating lateral along its ventral base;

interdentum n arrowly rhomboidal, poorly developed, absent in some; left pseudocardinals double, serrate, triangulate, separated by a sulcus, usually equal but variable in size, posterior tooth bordering well-developed rhomboidal to triangulate interdentum, dorsal margin parallel to the ligament; laterals double, scarcely curved, striate within and below, about equally developed, terminating gradually over the posterior qdductor cicatrix; anterior cicatrices moderately to deeply impressed, usually distinct, largely filled with a very rough nacreous deposit; posterior cicatrices lightly impressed, con­ fluent and continuous with the pallial line which becomes deeply impressed anteriorly; dorsal suspensory cicatrices distributed on the under side of the interdentum in each valve; umbonal cavities deep*

Habitat. Specimens were collected from the pond, inner bay, and outer bay from waters less than three to over 21 feet deep. In every case, however, they were taken from a firm sand or sandy-gravel sub­ strate. While none were taken from the mud (silt) area of the inner bay, they have been occasionally taken from a similar bottom in the 1 2 0

TABLE 13. SUMMARY OF DIMENSIONAL AND PROPORTIONAL DATA OF SHELL MORPHOLOGY OF AMBLEMA PLICATA

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index Minimum 10 9 61 5 1*1*

Mean 6U 1*5 73 30 1*8

Maximum 96 66 90 111* 53

Range 86 57 29 39 9

Number of specimens * 16.

TABLE ll*. DIMENSIONAL AND PROPORTIONAL DATA OF AMBLEMA PLICATA RELATED TO LENGTH (SIZE) GROUP

Length Number Mean Mean Mean Mean Mean Group of Length Height Height Width Width (mm.) Specimens (mm.) index (mm.) (mm.) Index

9-9 0 -- - --

10-19 1 10 9 90 5 5o

20-29 0 - mm ---

30-39 3 33 25 75 16 1*9

1*0-1* 9 1 1*8 36 75 2i* 50

50-59 0 - - - - -

60-69 1 62 1*5 73 27 10*

70-79 6 71* 51* 73 36 1*9

80-89 3 86 56 65 1*0 1*6

90-99 1 96 66 69 10* 1*6 1 2 1 open lake beneath about forty feet of water. Such specimens are so extremely stunted they are scarcely identifiable.

The youngest specimens were all found in the shallow water of the inner bay thus suggesting a possible migration with age to deeper water. This is doubted, however, because in streams the young and old may be found intermixed on riffles only one foot deep*

It was also noticed that none of the A. £. peruviana were found in the outer bay and that all but one of the specimens taken in shallow water were this form. It is possible that this is due to the fact that the youngest specimens which usually have a greater relative width, were taken in the shallows. The sample size here is rather small-even for speculation, and more material with data is needed if one is to arrive at any valid conclusions concerning habitat distri­ bution differences between these two forms*

Growth and Longevity

This species, like most of the Unioninae, grows slowly, rather steadily, and usually attains an age greater than almost all other

Lake Erie naiades. The only previous studies concerned with the growth of this species are those of Coker et al. (1921:159) and Grier

(1922:13^). Coker's observations were on a single specimen of A. £• peruviana reared in a pond at the Fairport Laboratory on the Mississip­ pi River* This specimen had attained a length of 13*5 millimeters in approximately two years, a rate of about 6.8 millimeters per year*

It is rather surprising that the initial rate (for first five-year period) for Lake Erie specimens as recalculated from Grier is somewhat LAKE ERIE

HUNDRED FEET Peach Point

GIBRALTAR ISLAND

SOUTH BASS ISLAND Oak Point

Hap XIII* Distribution of Amblema £* plicata (Say) and Ambloma plicata Peruvian^ (Lamarck) in Fishery Bay.

O Amblema Plicata plicata (Say).

9 Amblema plicata peruviana (Lamarck)* 123

greater than that for the river specimen. An explanation of this

apparent contradiction to the general rule may lie in the nature of

the Fairport rearing ponds*

Growth Rate (mm./yr.) 0-5 6-10 11-20 Maximi yrs. F s- Age

Inner Bay Bar 8.8 — — 5

Inner Bay Channel 5.8 U.6 2.U 32

Outer Bay U.U 3.U 2.1 25

Deep Lake (muck) 3.2 3.2 2.7 2U

Grier (1922:135) 8.U 6.0 2.8 16

Coker et al. (1921:159) 6.8 (pond reared A. £. 2 peruviana)

It can be seen from the table that the most rapid growth of

young specimens occurs on the bar and that the rates decrease with

an increase in depth accompanied by a corresponding decrease in

current. The slowest initial rate was found for those individuals

dredged from a muck bottom in the open lake. Although these deep

lake naiades have a markedly slower initial rate (less than half of

that on the bar), this rate is maintained for the second five-year period while rates elsewhere decrease. A decrease is observed after

the tenth year but it is relatively small so that after this time the deep lake individuals are growing more rapidly than the others.

While it might seem that the "compensatory growth" exhibited by the deep lake specimens would result in their attaining (given adequate 1 2 U

time) the size of their shallow water counterparts, this has not

been observed to occur. The growth curves of two populations

approach each other asymptotically and apparently never quite meet.

Sexual dimorphism does not occur in this species so it is not

possible to determine the age of sexual maturity by this means*

A study of the annular ring periodicity of the Fishery Bay specimens

reveals a marked change between the eight and fourteenth years.

There is a large amount of variability among individuals as is in­

dicated by the given range. While there is no direct evidence on

this question at present, the persistent occurrence of the growth

curve inflection at the onset of sexual maturity in most species of

Lamsilinae indicates that the same technique might be applicable in

the Unioninae. If such an inference be correct, this species is one

of the very latest to mature and may lag behind the early-maturing thin shelled Anodontinae by as much as 6-12 years.

The oldest shell aged in this study was estimated at 32 years*

Its length had increased by approximately one millimeter each year for its last five years of life. An annual increase greater than two millimeters had not been made during the last 16 years of life*

Several specimens were eroded so badly in the umbonal region they could not be aged. A count of the annular rings outside the eroded area of one specimen (OSU 3088) gave a figure in excess of 3>0 years which, if correct, establishes this species as one of the longest-lived naiades of the area* 125

TABLE 15. AGE-LENGTH RELATIONSHIP OF AMBLEMA PLICATA

______Inner Bay Channel______Inner BayBar ____ Number Number Annulus Measure- Length (mm.) Annulua Measure- Length (mm,) Number ments Min. Mean Max* Number ments Min. Mean Max.

1 0 -_- 1 3 2 2 2 2 U 10 13 15 2 U 11 13 1U 3 5 15 18 21 3 U 19 2U 31 U 5 20 2U 28 U 1 32 5 5 28 29 33 5 1 UU 6 5 32 3U 36 7 5 37 38 Uo 8 5 UO 12 U5 9 5 U2 U7 52 10 5 U8 52 57 11 5 52 56 61 12 5 53 60 66 13 5 55 63 68 1U 5 57 65 70 15 5 59 67 73 16 5 6l 70 75 17 U 63 71 77 18 U 65 73 78 19 3 67 72 77 20 3 68 73 78 21 2 69 72 75 22 2 70 73 76 23 2 71 75 78 2U 2 72 76 80 25 2 73 77 81 26 2 7U 78 82 27 1 - 8U 28 1 - 86 - 29 1 - 87 - 30 1 88 - 31 1 - 89 - 32 1 - 90 - 1 2 6

TABLE 16. AGE-LENGTH RELATIONSHIP OF AMBLEMA PLICATA (SAY)

Outer Bay ______Deep Lake Number Number Annulus Measure- Length (mm.) Annulus Measure- Length (mm.) Number ments Min. Mean Max. Number ments Min. Mean Max.

1 0 1 0 - 1 - 2 2 11 11 11 2 3 6 7 8 3 2 lU 15 15 3 U 8 10 12 U 2 16 18 19 UU 11 13 16 5 2 18 22 25 5 U 15 16 18 6 2 21 25 29 6 U 18 19 21 7 2 2U 29 33 7 U 21 23 25 8 2 28 32 36 8 U 2U 27 28 9 2 31 36 UO 9 U 26 29 33 10 2 36 39 U2 10 U 28 32 36 11 2 38 Ul UU 11 U 31 35 39 12 2 UO U3 U6 12 U 3U 2 9 U2 13 2 U2 U5 U7 13 u 37 U2 U5 lU 2 U5 U7 U8 1U u Ul U5 U9 15 2 U9 50 50 15 u UU U8 52 16 2 51 52 52 16 u U8 52 56 17 2 53 5U 55 17 u 50 53 58 18 2 5U 56 57 18 u 51 55 60 19 2 56 58 60 19 u 52 57 63 20 2 58 60 61 20 3 53 59 66 21 2 59 61 63 21 2 60 6U 67 22 2 60 63 65 22 1 _ 62 23 2 61 6U 67 23 1 - 6U - 2U 1 _ 68 • 2U 1 - 65 - 25 1 - 69 - 127

Remarks

Barnes (1823:121) believed plicata Say, 1817, to be the large

river form and so it was interpreted in general by most, if not all,

naiad students until Ortmann's time. Ortmann (1912:21*6) noted that

"the type locality of plicata is Lake Erie, and thus the only known

Crenodonta from Lake Erie should bear this name, but this is the form

called hippopaea by Lea. The plicata of authors (incl. Simpson)

should be Cr. peruviana (Lamarck)."

The anatomy of the soft parts of Lake Erie specimens and upper

Ohio drainage specimens were studied by Ortmann (1912:21*6) and declared

to be absolutely identical in every respect. He thus concluded that

they were conspecific and he treated them so in his Pennsylvania

Bonograph (Ortmann 1919:2$). Ortmann and Walker (1922), with the aid

of Pilsbry, reviewed many of the contested naiad names in an effort

to eliminate much of the confusion which resulted largely from the

poor descriptions of Rafinesque and Lamarck. It was concluded that

the three forms A. costata (Raf. 1820), A. plicata (Say, 1817), and

A. peruviana (Lamarck, 1819) were identifiable from the original des­

criptions and hence valid. They were recognized here as the headwater,

large river, and lake forms, respectively. While this action

clarified the nomenclatorial confusion it didnot, nor was it intended

to, resolve taxonomic difficulties. If, as we have tentatively con­

cluded the type of plicata Say is the headwater form, then costata Raf. becomes its synonym and there remains the problem of differentiating

between plicata Say and peruviana Lam. when dealing with material

containing intergrades. Ball (1922:106) made a study of the inter- AVERAGE LENGTH IN MILLIMETERS lOOi 0 4 0 6 20 ao 0 rp I Age-LengthGraph II* Relationship of Amblema Plicata (Say)* 4 BAY INNER BAR 8 12 SIAE AE N YEARS IN AGE ESTIMATED 16 20 24 832 28 36 40 00 K 1 2 9

gradation of stream dwelling naiades including the forms dealt with

here. He concluded that they were conspecific and that those with a

width index (obesity) of 1*7 and less should be classified as the

headwaters form while those over 1*7 constituted the large river

form. While this technique has the disadvantage of not taking into

account other characteristics, such as the anteriorly placed swollen

umbones, it is recognized that other large river features are rather

consistently associated with the increase in relative width.

All of the Lake Erie specimens in the collection were measured

and their width indices calculated to determine whether one or two

subspecies were present. The results are canspared below with calcu­

lations made from data presented by Rafinesque (1820:315) (1832*57),

Call (1900:1*1*5, p. 13), Simpson (1911*, 185, 820), Vanatta (1915*556),

Ortmann (1919:29), and Baker (1928:71*, 81). The rarlplicata Lam.,

1819, is apparently an intermediate form while the entry from Vanatta

is the so-called Rafinesque-Poulson type of A. costata (Raf.).

Length Height Height Width Width No. Form (mm.) (mm.) Index (mm.) Index Spec. Authority costata (Raf.) (only proporti ons given) 38 1-? Raf. (1820) costata (Raf.) 81 59 73 26 1*1* 1 Call (1900) costata (Raf.) li*7 99 68 5U 37 3 Simpson (1911*) costata (Raf.) 66 53 80 21* 36 1 Vanatta (1915) costata (Raf.) 130 101 78 53 Ul 2 Ortmann (1919) costata (Raf.) 106 73 69 1*6 1*3 7 Baker (1928) rafiplicata (Lam.) 109 82 76 51 1*7 8 Baker (1928) 1 3 0

Length Height Height Width Width No. Fora (mm.) (mm.) Index (mm.) Index Spec. Authority peruviana (Lam.) 110 78 71 51 L6 3 Simpson (191L) peruviana (Lam.) 73 56 76 L2 57 L Baker (1928)

Specimens of Amblema sp. from the Western Basin of Lake Erie

7U Individuals

Minimum 10 9 6l 5 U2

Mean 60 L5 75 28 L7

Maximum 96 66 90 Ilk 59

The range of variation of the width index of the Lake Erie material studied does not include the low extreme exhibited by the specimens of Rafinesque, Vanatta, and Simpson above. This also holds true for characteristics other than relative width such as development of the.umbones, plications of the wing, lunule outline, as well as the number and depth of the plications of the disc.

The maximum width index of 59 compared to the high of 57 in the table suggests that this species reaches its greatest obesity in

Lake Erie. Although this is not true, the result of a paucity of data of this sort in the literature and the effect of presenting the means rather than the extremes of the data that do exist gives this impression. Two of the four specimens listed by Baker (qp. cit.) had indices of 59* I have examined specimens in the mollusk collection at the University of Michigan which appeared to have an index in excess of 70. While the Amblema plicata population in Lake Erie has 131 wore peruviana (Lam.) individuals thah plicata (Say) individuals, neither extreme of development is reached by these dwarfed individuals.

When Ball's criterion (1922:106) of the width index value of h7 is used in separating the 7k Lake Erie specimens into subspecies, it is found that U6 individuals, or 62 per cent, are A. p. peruviana and

28 individuals, or 38 per cent, are A. p. plicata.

Since all these individuals appear to be more or less inter­ grades (and stunted ones at that) it is probably best to drop the tri­ nomial for Lake Erie specimens and refer to them simply as A. plicata.

The fact that the mean width index of the Lake Erie collection is U7, exaetly the mean of variation determined for stream specimens, sub­ stantiates the intermediate position of these naiades and indicates that the Lake Erie basin is a rather unusual zone of intergradation between two stream subspecies. The classification of this species and its synonomy of described names thus becomes:

Amblema plicata plicata (Say, 1817). Unio plicatus Say, 1817. Unio raripllcata Lamarck, 1819 (in part). Amblema costata Rafinesque, 1820* Unio undulatus Barnes, 1823. Unio latecostata Lea, l8U£. tlnio hippopaea Lea, 181j5. (in part) Unio pilsbryl "Marsh, 1891. Amblema costata eriganensis Grier, 1920 (in part). Amblema plicata peruviana (Lamarck, 1819). Unio peruviana Lamarck, 1819. Unio rariplicata Lamarck, 1819 (in part). Unio crassus Barnes, 1823. Unio qiganteus Lea, 1838, Unio hippopaes Lea, l8UE> (in part). Amblema costata eriganensis Grier, 1920 (in part). 132

There remains the possibility that the type specimen described by Say may have been a dwarfed specimen of the large river form.

Even if this were found to be true it would not necessitate a change in taxonomy but rather a change of the subspecific trivial names.

A. £. plicata would then represent the large river subspecies with peruviana (Lam.) in its synonomy and A. £. costata would represent the headwater subspecies. That this is the case is indicated by the action of Barnes (1823:120, pi 3) in figuring and describing a large river form to which he assigns the name Unio plicatus. He presumably had only Say’s published figure to use in making this decision and he further strengthens this position by describing (with a figure, p. 2) the headwater form giving it the name Unio undulata. This matter, even though it does not involve the species trivial name, should be investigated and settled. 133

QUADRULA QUADRULA QUADRULA (RAFINESQUE, 1820) (lT quadras - square; ula ■ small) Figures 19, 20, 21, page 135

Synonomy

Obliquaria quadrula Rafinesque, 1820. Rafinesque (1820:307)* Unio rugoius Barnes, 1823* Barnes (1823:126). Unio lachrymosus Lea, 1828. Lea (1828:272)* Unio asperrimus Lea, 1831* Lea (1831:71). Unio quadrulus Say, 183b* Say (183U: )• Unio fragosus Conrad, 1836. Conrad (1836:12). Margarita lachrymosus (Lea, 1828). Lea (1836:1U). Margarita asperrimus (Lea, 1831). Lea (1836:1U). Margarita fragosus (Conrad, 1836). Lea (l836:lli). Unio tragosus Hanley, 18U3* Hanley (181*3:178). Margaron lachrymosus (Lea, 1828). Lea (1852:21)* Margaron asperrimus (Lea, 1831). Lea (1852:21). Margaron ilragosus~TConrad, 1®36). Lea (1852:22). Unio quadratus Reeve, 186U. Reeve (I861*:p. VI, fig. 2lt). Mnio lunulatus Pratt, 1876. Pratt (1876:167)* Quadrula lachrymosa (Lea, 1828). Baker (1898:83). Quadrula lachxymosa lunulata (Pratt, 1876). Sinqpson (1900: 77777 Quadrula fragosa (Conrad, 1836). Simpson (1900:777)* Quadrula quadrula (Rafinesque, 1820). Vanatta (1915:556). Quadrula quadrula quadrula (Rafinesque, 1820). Neel (19itls1)•

Type Locality

Ohio River (Poulson, 1832:1|2).

Type Specimens

Primary types never designated. Metatype (Rafinesque-Poulson

type) A. N. S. P. 2022U (Vanatta, 1915:556).

Lake Erie Records

1898 Unio asperrimus. Walker, p. 5 (footnote).

Detroit River at Belle Isle

1907 Quadrula lachrymosa. Sterki, p. 390.

Lake Erie 13U

1913 Quadrula lachrymosa. Walker, p. 22.

Lake Erie

1919 Quadrula quadrula. Ortmann, p. Ul.

Presque Isle Bay, Erie Co., Pa.

1932 Quadrula quadrula. Goodrich & van der Schalie, p. 12.

Lake Erie

\ 1932 Quadrula quadrula. Goodrich, p. 86.

Beach at Monroe Co., Mich.

1937 Quadrula quadrula. LaRocque & Oughton, p. 15>3*

Lake Erie

Niagara River

19U1 Quadrula quadrula. van der Schalie

L8ke Erie

19U8 Quadrula quadrula. Robertson & Blakeslee, p. 9U*

Niagara River, Cayuga Is., Erie Co., N. Y.

Niagara River, above falls

1953 Quadrula quadrula. Wood, p. 56.

Gibraltar Is., Ottawa Co., Ohio

195U Quadrula quadrula. Langlois, p. lf>3»

Lake Erie, western end

There is little difference in proportions or sculpturing between the stunted population of Q. quadrula found in Lake Erie and specimens of the same species from the tributary streams. The differences in growth rate and size, however, can be quite remarkable. This is QUADRULA QUADRULA QUADRULA (RAFIHESQUE, 1820). September 20, 1956 Fishery Bey of Lake Ikie Length 55 mm. Approx. Age 5 years Put-in-Bay Twp., Ottawa Co., Ohio Height U4 mm. OSU 3066 Figures 19,20,21 Width 2? mm. 136

demonstrated by the growth curves and is seen to exist between

specimens from different bay habitats as well as between lake and

stream specimens.

Sterki (1907:390) noted that this species was decidedly variable

in Ohio and that "The Lake Erie form is little inflated and has few

tubercles, . . This lake form was not given separate taxonomic

standing by Sterki nor by any other workers. This was fortunate

since the form described by Sterki apparently was not typical of the

species in Lake Erie. None of the material studied from Fishery Bay,

and elsewhere in the western basin, exhibit any decrease in width or

sculpturing except in relation to over-all size.

Fishery Bay Records

Collection Cat. No. Date Site Collector

OSU 1577 111:22:1955 Causeway Cut D.H.S.

OSU 29U1 Summer:1956 Outer Bay W.C. Coil

OSU 3066 DC:20:1956 Inner Bay D.H.S.

Shell Characteristics

Size small to medium; subinflated; outline subquadrate, occas­ ionally sUbrhombusoid; dorsal margin straight, connected by means of a rounded angle with the straight posterior margin, postbasal angle 90° or slightly less, ventral margin emarginate posteriorly, fiilly rounded anteriorly, becoming straight or nearly so approaching the lunule; anteriorly inequipartite, beaks of umbones inverted over the lunule in 137 non-eroded specimens; beak sculpture a series of v-shaped nodules down the posterior ridge accompanied by a similar series on the lateral ridge, the innermost two to three sets being connected, forming concentric VPs, the outside bars of both V’s and ¥*s are re­ curved anteriorly in undulatory ridges to the margin of the lunule, the posterior bars extend in straight parallel lines back toward the beaks; the disc sculpture appears to be the enlarged, broken up, con­ tinuation o f the beak sculpture, two zones of prominent tubercles extend out over the disc associated with the posterior and lateral ridges respectively; the tubercles on the posterior ridge are usually present as a single row of protuberances while those upon the lateral ridge may number as many as three to five at any one level; these structures tend to increase in size out to the fourth, fifth, or sixth annulus where they become broad, low and Inconspicuous or absent; anterior third of the disc usually free of tubercles except for the area within the second or third annulus; both lateral and dorsal ridges well defined, forming a distinct medial sulcus which is usually free of tubercles, posterior ridge forms with the dorsal margin a shallow sulcus which is ornamented within the first four to six annuli with a number of rather fine nodular interrupted corruga­ tions, which pass from the posterior ridge, usually becoming obsolete as they approach the dorsal or posterior margin; shell solid, perio- stracum greenish-yellow, with or without poorly defined irregular green rays, older shells becoming brown; growth lines narrow, well 138 defined, impressed when young, color variable but without raysj lunule

linear, width occasionally over half the length, ligament brown, moderately strong.

Nacre white, iridescent posteriorly; right pseudocardinal tri­ angulate, serrate, heavy, separated from the hinge line by a sulcus and accompanied by a low supernumerary denticle which is located on the hinge line just beneath the anterior lunule; right lateral single

scarcely curved, striate above and below, and accompanied by a low

supplemental lateral along its post-ventral base; interdentum rhomboidal; left pseudocardinals double triangulate, serrate, separated by a sulcus

and particularly heavy; interdentum fchomboidal; laterals double, scarcely curved, striate within and below; anterior cicatrices deeply impressed, distinct; posterior cicatrices lightly Impressed, confluent;

dorsal suspensories on tinder surface of interdentum in both valves with a few scars on under surface of posterior pseudocardinal in left valve; pallial line distinct, closest to posterior and posterio- ventral margina; umbonal cavity moderately deep.

Habitat

While only three specimens of this rather rare species were taken from the bay, each was taken from a somewhat different habitat.

One was found in the gravel bottom of the causeway cut, one was col­ lected about fifty yards out in the bay from this location on a firm sand substrate and the third was dredged from the silt area of the outer bay. Wood (19f>3;56) collected a single specimen from a sand 1 3 9

TABLE 17. SUMMARY OF DIMENSIONAL AND PROPORTIONAL DATA OF QUADRULA QUADRULA QUADRULA (RAFINESQUE)

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index Minimum 22 17 77 10 U5

Mean 36 29 80 17 U7

Maximum 55 UU 8U 27 U9

Range 33 27 7 17 U

Number of specimens “ 3

TABLE 18. DIMENSIONAL AND PROPORTIONAL DATA OF QUADRULA QUADRULA QUADRULA (RAFINESQUE) RELATED TO LENGTH (SIZE) GROUP

Length Number Mean Mean Mean Mean Mean Group of Length Height Height Width Width (liw.) Specimens (mm.) (mm.) Index (mm.) Index

0-9 0 - - - - -

10-19 0 -- - m* -

20-29 1 22 17 77 10 U5 30-39 1 31 26 8U 15 U8

U0-U9 0 «• -- --

50-59 1 55 UU 80 27 U9 lUo

bottom off the east side of Gibraltar Island and another from the deep

lake off the southwest shore of Kelley's Island— again from a sandy

substrate. Goodrich (1932:86) notes concerning this species, "Though

rare in the extreme west end of Lake Erie, it occurs fairly plenti­

fully in the vicinity of Put-in-Bay. . The basis of this statement

may be the fact that the University of Michigan collection had, at

that time, only a single specimen of this species from Michigan and

that came from the Lake Erie beach of Monroe County. The series of

ten specimens in the Ohio State University collection from the island

region could be considered "fairly plentiful" when compared to a

Single individual. This species, however, should not be considered common in the area. There is a possibility that this and several other uncommon naiads in Lake Erie may not have breeding populations

in the lake. Individuals in our meager collections may have developed from glochidia carried from stream populations to the lake by host fish. While the life history of this mussel has never been worked out, there is a large population of this species in the lower

Maumee River (Clark & Walton, 1912:1*1) (Goodrich, 1932:86).

Growth and Longevity

This naiad appears to have a growth rate which is profoundly affected by habitat. The growth curves of the few specimens from

Fishery Bay were so widely divergent that similar curves were con­ structed from additional specimens from Sandusky Bay and the Portage

River. Rates were calculated for these two habitats in addition to the inner and outer areas of Fishery Bay* LAKE ERIE

HUNDRED FEET Peach Point

GIBRALTAR ISLAND

SOUTH BASS ISLAND Oak Point

Map XIV. Distribution Records of Quadrula £• ouadrula (Rafinesque) and Quadrola pustulosa (Lea) in Fishery Bay*

• Quadrula quadrula quadrula (Rafinesque).

O Quadrula nustulosa (Lea) • 1U2 Growth Rate (mm./yr.) 0-5 6-10 11-20 Maximum Growth Period yrs. yrs. yrs. Age mmmmmmm rnmmmmmm m x m m

Locale Substrat*

Portage River Coarse gravel 15*6 6.0 8

Inner Bay Sand and gravel 10.0

Sandusky Bay Sandy mud 6.0 5.8 1.7 13

Outer Bay Silt 3.6 2.0 6

It should be kept in mind that larger samples probably would

have revealed smaller differences between the mean rates of different

environments. The above data demonstrate, however, that the growth

rates of individuals may vary by as much as a factor of four during

the same growth period and by as much as a factor of nine in dif­

ferent growth periods in different habitats. The extremes listed here may prove to be low when additional material is studied.

The problem arising from a consideration of these and other

similar growth-rate-differences in this report is that of cause.

Several previous workers have attempted to explain either the stunting of the Lake Erie mussels (Grier, 1922:lU5) or the variation existing within the lake itself (Brown, et al. 1938). Grier suggested that

certain soluble salts may have a regulatory effect on growth, and found (1920:15) a negative correlation between shell thickness and the calcium concentration of the water. Brown et al. concluded that the degree of stunting ". . . is definitely correlated with the degree of exposure found in the habitats. The more stunted individuals were found in the more exposed lake habitats." TABLE 19. AGE-LENGTH RELATIONSHIP OF QUADRULA QUADRULA (RAF.)

Inner Bay Outer Bay . Number . . Number Measure- Length (mm.) Numbed Measure“ ^Length (mm.)_ Number Meats Mini Mean Max.' ments Min. Mean Max.

1 2 8 8 8 1 1 mm 5 * 2 2 17 20 22 2 1 mm 8 - 3 2 29 32 3k 3 1 - 11 - - U 1 - Uo U 1 - 15 • 5 1 - 5o - 5 1 - 18 - 6 1 20 -

Sandusky Bay Portage River

1 2 5 5 5 1 2 8 10 12 2 2 ll n 11 2 2 32 3k 36 3 2 17 18 18 3 2 51 55 59 k 2 23 2h 25 U 2 67 70 72 5 2 30 30 30 5 2 7U 78 82 6 2 37 38 38 6 2 83 85 86 7 2 kh U5 U6 7 2 87 89 91 8 2 L8 50 52 8 2 93 96 99 9 2 52 55 57 10 2 57 59 61 11 2 60 63 65 12 2 62 65 67 13 1 •» 6U mm

My observations on specimens from Pelee Island, Fishery Bay, and East Harbor agree with those of Brown et al. as to the degree of. stunting but the data presented in this study do not support exposure as the causative factor. If exposure produces stunting then it follows that the larger, fast-growing, members of a species should be found in the deep, quiet waters, away from currents and wave action.

In the seven species included in this study, the rapid-growing individuals were taken in relatively shallow water from coarse bottom nustulosa AVERAGE LENGTH IN MILLIMETERS 20 40 60 0 rp 7 Age-JjengthGraph17, Relationship of Quadrula INNER BAY (Lea), > u 40 5 60 Z

of Quadrula quadrula quadrula (Rafinesque) 100 20 80 4 0 Graph SIAE AE N YEARS IN AGE ESTIMATED SIAE AE N YEARS IN AGE ESTIMATED 12 8 III* III* 4 OUTER BAY Age-Length Relationship BAY 12 8 O TAGEPOR NDUSKYBAY SA VER 16 20

DEEP LAKE 24 IU*> sediments. The slow growing specimens came from relatively deep waters and soft substrates. Very few naiades were found in water less than two feet in depth except in Terwillegar's Pond. Outside the pond the rocky shores were generally found to be devoid of all but worn and broken shells. The few specimens taken from the exposed rocky shallows (less than one foot deep) were stunted but had shells that were very heavy compared to the weight of shells of deep water speci­ mens of approximately the same age and length.

Although fine sediments and deep water are associated with stunting in this study, it is my opinion that one is not the result of the other, but that both are produced primarily by the nature of the water. The substrate is principally determined by the nature of the sediments carried in suspension in the water and the current (es­ pecially the extremes) at the site of interest. This determines what sediments will be deposited and when and where. Since the naiad feeds upon particulate matter in suspension in the water, it follows that the nature of such sediments (i.e., particles) and their avail­ ability should be two major factors affecting the food supply and, hence, the growth rate of these animals. Depth in quiet bodies of water, such as lakes, largely determines the zones of productivity- other things being equal. Only those depths receiving light will be capable of supporting populations of autotroph!c plankters.

While there are enough exceptions to the above to demonstrate the existence of other factors of appreciable magnitude, the data indicate that this conclusion is a valid inference in regard to the 1U6 action of at least two factors. While the mean yearly nutritive value of the water over a given area of substrate is difficult to measure, depth is not; and while the mean yearly current over this same area would be difficult to determine, the nature of the substrate is readily observed. While these things are not equivalents, it seems that the associations are close enough to enable one to use depth and substrate in predicting degree of stunting— other things being equal*

This theory may be represented graphically by arranging a set of arbitrary indices of stunting and relating them to depth of water and size of sediments*

In the table below it is shown that the degree of stunting increases directly with decrease in sediment size and increase in depth. Thus it is that the least stunted individuals are found in shallow waters on coarse substrates while the specimens from deep waters and soft bottoms exhibit the least growth during the same period of time*

Sediment Size Depth Coarse Mle'dlum Fine Very Fine Shallow 0 1 2 3

Moderately Shallow 1 2 3 U

Moderately Deep 2 3 U 5

Deep 3 U 5 6

The numbers above indicate degree of stunting found in western

Lake Erie as related to depth and sediment size* 1U7

Remarks

The stunted individuals which make up the lake population of

Q. q. quadrula have never been given a separate varietal, subspecific

or specific name* This is not because the form Is little affected

by the lake environment but probably because it is such an uncommon

species in the lake. Ortmann (1919:1+3) noted that Sterki’s des­

cription (1907*390) "fits the specimen before me, but I cannot judge

from a single example whether this is a constant difference.n

This is one of the few species complexes given careful study

in relatively recent years. Neel (19Ul) made a taxonomic study of all forms of this species, using the extensive collections at the Museum of Zoology of the University of Michigan. He concluded that the fourteen different described entities were in reality all forms of the same species, and that, within this widely distributed taxon, there were only two forms which could be recognized as subspecies.

The following classification is essentially that of Neel*

Quadrula quadrula quadrula (Rafinesque, 1820). OSbliquaria quadrula Rafinesque, 1820. Unio rugosus Barnes, 1823* Unlo lacrymosus Lea, 1828. Unio asperrimus Lea, 1831. Unio quadrulus"~Rafinesque, 1835. Unio fragosus"Conrad, 1836. Quadrula quadrula apiculata (Say, 1829). Unio aptcuiatus Say, 1829. Unio asper LeaT 1831. Unlo rumphianus Lea, 1852* Unio nobilis Conrad, 1 851*. Unio falandigianus Lea, 1 8 56* Unio forsheyii Lea, 1859* Unio speciosus Lea, 1862. Unio conjugans B.H. Wright, 1899. 1U8

QUADRULA PUSTULOSA (LEA, 1831) (L. quadras * square; L. ula - small) (1. pustula • blister; L. osus ■ having nature of) Figure 22, page 1$1

Sygonomy

Obliquaria bullata Rafinesque, 1820* Rafinesque (1820:307)* Unio pustulosus Lea, 1831* Lea (1831:76)* Unio verrucosa Valenciennes, 1833* Valenciennes (1833:231)* Unio nodulosus Say, 183U. Say (183U)* Unio prasinus Conrad, I83U. Conrad (183U*UU)» Unio ouilatus (Rafinesque, 1820). Conrad (I83l;:68). Unio schooleraftensis Lea, 183h» Lea (183U:37). Margarita pustulosus (Lea, 1831). Lea (1836:15). Margerita schooleraf tensis (Lea, 183k). Lea (1836:15)* Unio dorf euTTl1anus' LeaT*t838. Lea (1838:73). Margarita dorfeuiillanus (Lea, 1838).. Lea (1838:15)* Onto pernodosus Lea, l8ii5» Lea (18U5:163). Unio keinerianus Lea, 1852. Lea (1852:251). Margeron pustulosus (Lea, 1831). Lea (1852:22). Margaron schoolcra?tensis (Lea, 183U0* Lea (1852:22). Margaron keinerianus (Lea, 1852). Lea (1852:22). Unio asperate Lea, 1861. Lea (l86l:Ul). Margaron schoolcraftii (Lea, I83U). Lea (1870:33)* Margaron asperatus (Lea, 1861). Lea (1870:33)* Margaron pernodosus (Lea, 18U£). Lea (1870:3U)* Unio schoolcraftii (Lea, I83U). B. H. Wright (1888). Unio bullatus prasinus (Conrad, 183W* Paetel (1890:1U6). Unlo bullatus schoolcraftensis (Lea, 183U)• Paetel (1890:1U6). Quadrula pustulosa (Lea, 1831)* Baker (1898:86). Quadrula pustulosa pernodosa (Lea, 181*5). Simpson (1900:780). Quadrula pustolosa keineriana (Lea, 1852). Simpson (1900:780). Quadrula pustulosa schoolcraftensis (Lea, 183U). Simpson

■ T 3m : f e r r ------Quadrula pustulosa prasina (Conrad, I83U)• Ortmann & Walker — 05^ : 1577^ — -----

Type Locality

Ohio: Alabama River (Lea, 1831:76). (Simpson, 19lU:8U9).

"Ohio (and incorrectly Alabama) rivers." (Ortmann and Walker, 1922:15).

hlme preoccupied (Ortmann & Walker, 1922:15)• 1 h9

Type Specimens

Holotype probably in the Lea Collection at the United States

National Museum, Washington, D.C.

Lake Erie Records

1907 Quadrula pustulosa kleineriana. Sterki, p. 391.

Lake Erie

1910 Quadrula pustulosa. Gary, p. 183.

Cedar Point

1912 Quadrula pustulosa schooleraftensis. Ortmann, p. 201.

Lake Erie

1913 Quadrula pustulosa. Walker, p. 22.

Lake Erie

1919 Quadrula pustulosa schooleraftens is. Ortmann, p. 39.

Cedar Point, Erie Co., Ohio

Presque Isle Bay, Erie Co., Pa.

La Plaisance Bay, Monroe Co., Mich.

1930 Quadrula pustulosa prasina. Ahlstrom, p. U7*

East Harbor, Erie Co., Ohio

Gibraltar Is., Ottawa Co., Ohio

1932 Quadrula pustulosa prasina. Goodrich, p. 8£.

Lake Erie at Monroe Co., Mich.

1932 Quadrula pustulosa prasina. Goodrich & van der Schalie,

p. 12.

Lake Erie 150

1937 Quadrula pustulosa. LaRocque & Oughton, p. 153.

Lake Erie

Niagara River

1938 Quadrula pustulosa. van der Schalie, p. U6.

Lake Erie

1938 Quadrula pustulosa. Brown, Clark, and Gleissner, p. 687.

Fishery Bay, Ottawa Co., Ohio

19U1 Quadrula pustulosa prasina. van der Schalie, p.

Lake Erie

19U8 Quadrula pustulosa. Robertson & Blakeslee, p. 9b.

Niagara River.

1953 Quadrula pustulosa. Wood, p. 56.

Put-in-Bay, So. Bass Is., Ottawa Co., Ohio

Kelleys Is., Erie Co., Ohio

1953 Quadrula pustulosa pustulosa. LaRocque, p. 98.

Quadrula pustulosa schoolcraftensis. LaRocque, p. 98.

Lake Erie

195b Quadrula pustulosa. Langlois, p. 153.

Lake Erie, western end

Fishery Bay Records Collection Cat. No. Date Site Collector

05U 16b III:3:195U Inner Bay D.H.S.

OSU 1829 XI:29:195b Inner Bay D.H.S.

05U 2950 Summer:1956 Inner Bay W. H. Coil 151

QUADRULA HTSTULOSA (LEA, I83I) October 11, I95U Western'Basin of Lake Erie Length h9 Approx, Age 15 years Put-la-Bay Tvp,f Height i»3 03U 1096 Ottawa Co,, Ohio Width 28 Figure 22

Cf CLONAIAS TUBEROULATA (RAFINESqUE, 1820) Middle Bass-South Bass Channel, September 20, 1958 Lake Erie, Put-in-Bay Twp,, Length 53 Approx, Age 23 year* Ottawa Co,, Ohio Height 48

OSU 3034 Figure 23 Width 26 III 183 152

Shell Characteristics

Size, small to medium; subinflated; outline suborbicular to sub-

quadrate, very old individuals becoming somewhat produced postventrally;

dorsal margin straight to scarcely curved as is the posterior margin

to which it is joined by a rounded angle; ventral margin evenly rounded

and continuous with the anterior margin which occasionally becomes

straight before terminating at the lunule; a slight emargination is

sometimes present just anterior to the post basal angle marking the

intersection of a shallow lateral sulcus with the margin; anteriorly

distinctly inequipartite; umbones rising above the hinge line, inverted

over the lunule; umbonal sculpture a series of concentric bars

represented by three to five triangulate nodules on the crest of the

posterior ridge, sharply bent forward toward the beaks on the posterior

slope and becoming obsolete on the lateral surface of the disc,

occasionally reappearing as a series of gently curved concentric arcs

on the anterior surface; innermost one or two bars continuous throughout

their length forming concentric trapezoids; area just beneath the

beaks without sculpture other than growth rings; posterior ridge

rounded but distinct, sometimes marked by an irregular series of

pustules but as often smooth; a very shallow sulcus or nonpustulate

path exists on the lateral surface of most specimens passing from the

beaks to the post-ventral margin between the posterior ridge and a

medial zone of pustulation; any pustules in this sulcus are greatly

reduced in size; posterior slope usually smooth but may be heavily

pustulose or rarely with a series of fine irregular horizontal bars which pass posteriorly from their origin on the posterior ridge; 153

sculpture obsolete Just beneath the beaks and near the margin of old specimens; some elongate pustules or ridges in the medial zone may be over ten times as long as wide; shell subsolid to solid; periostracura horn yellow to light brown becoming darker with age, rarely without a single broad bright green ray passing from the umbones over the lateral surface of the discs out to the fourth or sixth annulus, occasionally supplemented with one or two similar additional rays on the posterior slope; annular rings dark, narrow, regular, and well defined, becoming crowded near the margin of old specimens; ligament dark brown, heavy, and exposed; anterior lunule about twice as long as wide becoming somewhat cordate in obese specimens and linear in compressed individuals*

Nacre white iridescent posteriorly; post cardinal triangulate, serrate and single in the right valve, separated from the hinge line by a sulcus, occasionally accompanied by a pair of low denticles which are adjacent to but separated from the pseudocardinal by the sulcus; the anterior denticle lies on the hinge line beneath the lunule while the posterior denticle is a process on the ventral margin of the interdentum; right lateral single, straight or gently curved, obliquely striate above and below, abruptly terminating over the posterior cicatrices, usually accompanied by a low ledge or swelling along its post ventral base; interdentum rhomboidal, well developed; left laterals double, striate within and below, straight or gently curved; left pseudocardinals double, triangulate, serrate, separated by a sulcus, the anterior tooth distinctly larger, subtending and 15U

nearly parallel to the anterior lunule; posterior pseudocardinal a

process on the ventral margin of a relatively wide, well developed

interdentum; anterior cicatrices deeply impressed, distinct, posterior

cicatrices moderately impressed, confluent; dorsal suspensory scars

beneath the hinge plate in the region of the interdentum and pseudo­

cardinals; pallial line distinct and rather uniformly equidistant

from the margin throughout; umbonal cavity deep.

Habitat

Only three specimens of this species were taken from the bay during the course of this study. All were very young, probably

Juvenile, individuals. The largest specimen, only 21 mm. in length, was a dead shell. The smallest, eleven mm. in length, was collected alive by Dr. William Coil. All specimens were taken from a sandy- grave 1 substrate, which is the typical stream habitat of this naiade

(Call, 1900:1*88). Since this species has been shown to be parasitic

(as a glochidium) on several catfishes (Ictaluridae) (Coker, 1921:

152), it is not surprising that it is found inhabiting their feeding grounds. Although the bay specimens were taken from relatively shallow water, the species is not limited to such areas, since Wood

(1953:56) lists it from "... one-half mile southeast of Kelley’s

Island. . where the water is at least thirty feet deep.

Growth and Longevity

A growth rate of 3.3 millimeters per year (in length) was measured by Isely (19lU:10) from tagged specimens of 2* pustulosa TABLE 20. SUMMARY OF DIMENSIONAL AND PROPORTIONAL DATA OF SHELL MORPHOLOGY OF QUADRULA PUSTULOSA (LEA)

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index

Minimum 11 9 82 6 5U

Mean 15 13 87 8 55

Maximum 21 18 92 12 57

Range 10 9 10 6 3

TABLE 21. DIMENSIONAL AND PROPORTIONAL DATA OF QUADRULA PUSTULOSA (LEA) RELATED TO LENGTH (SIZE) GROUP

Length Number Mean Mean Mean Mean Mean Group of Length He!ght Height Width Width (mm.) Specimens (mm.) (mm.) Index (mm.) Index

0-9 0 -- - -

10-19 2 12 11 87 7 55

20-29 1 21 18 86 12 57 156 which had been recovered after being planted in a stream. It is un­ fortunate that the age of these specimens was not recorded so that this figure could be compared with rates calculated herein. Since the bay material for this species is represented by only three young

specimens, data are also presented from a single deep lake specimen, a single Sandusky Bay specimen, and a set of four specimens labeled simply "Put-In-Bay."

Growth Rate (mm./ 0-5 6-10 11-20 Maximum Growth Period yrs. yrs. yrs. Age Locale Substrate

Inner Bay Sandy Gravel 7.3 — — 3

Put-In-Bay ? 7.0 5.0 1.5 22

Sandusky Bay Mud 3.U 3.8 1.7 32

Deep Lake Muck 3*2 3.0 10

The rates were entered in the above table in order of decreasing magnitude. Again it is observed that the coarsest substrate and the least depth are associated with the greatest initial growth rate.

While it is not certain precisely where the "Put-in-Bay" material was collected, it would not be surprising, in view of the calculated rates, to learn that the specimens were taken from the inshore shallows having a rather coarse bottom and a fair current.

One of the most interesting rates in the table is the 6-10 year rate of the Sandusky Bay specimen. This is the only instance in the 157

TABLE 22. AGE-GRCWTH RELATIONSHIP OF QUADRULA PUSTULOSA (LEA)

Inner Bay Lake Erie Number Number Annulus Measure- Length (mm.) Annulus Measure* Length (mm.) Number ments Min. Mean Max. Number ments Min. Mean Max.

1 2 U 5 6 1 0 ___ 2 2 lli 15 15 2 ii 8 9 10 - 3 1 22 3 . U 11 13 111 li U 13 16 18 5 U 18 21 23 Sandusky Bay 6 li 20 2li 27 7 li 23 27 31 1 0 - M 8 U 27 31 35 2 1 - 8 9 li 30 3U 37 3 1 - 10 10 U 33 36 1|0 U 1 - 13 •a 11 U 35 39 1+2 5 1 - 17 - 12 li 37 111 lilt 6 1 - 22 - 13 3 39 1|2 U5 7 1 27 - 1U 3 1|0 Uli U7 8 1 - 30 - 15 3 1|2 Ii5 1+8 9 1 — 33 - 16 Uli U6 hi 10 1 - 36 - 17 1 - U8 11 1. a 39 •a 18 1 - U9 - 12 I a Ul - 19 1 - 50 a. 13 1 - U3 - 20 1 - 51 — lh 1 a U5 - 21 1 - 52 — 15 1 — U6 W 22 1 a. 53 _ 16 1 — H7 - 17 1 - Ii9 mm 18 1 - 51 - 19 1 52 - Deep Lake 20 1 - 53 aw 21 1 - 51 mm 1 0 - «■ 22 1 - 56 - 2 1 mm 6 - 23 1 - 57 m 3 1 mm 9 mm 2ii 1 ~ 59 «a h 1 2 13 - 25 1 - 60 a. 5 1 m 16 _ 26 1 - 61 - 6 1 mm 19 — 27 1 62 - 7 1 ■ — 22 . 28 1 a* 63 - 8 1 25 _ 29 1 - 61i - 9 1 • 28 «. 30 1 - 65 - 10 1 - 31 • 31 1 - 66 - 32 1 67 - 169 entire study in which the growth rate increased during this second

growth period. The nearest approach to this phenomenon is the rate calculated for deep lake A. plicata which remained (averaged) the same during the first two periods. Although this growth curve was not plotted it seems that such a change in rate, when expressed as yearly increments, would be likely to exhibit the lower half of the character­ istic sigmoid growth curve when graphed.

Remarks

The stunted lake form of Q. pustulosa has been variously referred to in the past under the names pustulosa Lea, schoolcraftens!S

Lea, and prasinus Conrad. Ortmann and Walker (1922:16) record the unusual fact that both prasinus Conrad and schoolcraftensis Lea were founded on the same specimen in the same year, 183b. Conrad's name had priority over Lea’s name by a matter of only five months. Van der

Schalie (191+1) recognized prasina Conrad as the environmental lake form of Q. pustulosa (lea, 1831)— which name has priority by three years. Thus it is that we recognize here a single variable species having no well defined genetic subgroups which could be termed subspecies. The synonomy of descriptions is as follows:

Quadrula pustulosa (Lea, 1831)* Obiiguaria bullata Rafinesque, 1820. Unio pustulosus Lea, 1831. Unio verrucosa Valenciennes, 1833. Unio nodulosus Say, 183b. Unio prasinus"Conrad, 183b. Unio schoolcraftensis Lea, 183b. Unio dorfeuillianus Lea, 1838. Unio pernodosus Lea, I8b5>. Unio keinerianus Lea, l8f>2. Unio asperatus Lea, 1861. Just what factors are responsible for the indicated small size of the population in this area are not known. The host fishes Ictalurus melas (Rafinesque), Ictalurus nebulosus (LeSueur), and Ictalurus punctatus (Rafinesque) are common in the island region. One factor not investigated here is a possible insufficient association of naiad and host at the time of the release of glochidia. 2* pustulosa is, as are all Unioninae, a tachytictic breeder. The length of the period during which glochidia are released is not known but it occurs during July and/or August (Coker, et al.).. Since adults are seldom found in the gravid condition, this period is probably quite short*

The age of maturity and reproductive life span are also factors which influence the reproductive potential of a population and are also facts of which we are ignorant in the case of almost all species of Unioninae. The periodicity of the annular rings of this species first changes markedly at seven to eleven years of age, suggesting either a very late maturity or a rather early senility.

Matteson (19U8:7lU) notes that Elliptio complanatus (Dillwyn), a Unionid naiad, becomes sexually mature at least as early as the end of the third growing season. An examination of E. complanatus shells in the QSU collection reveals that the periodicity change at the fifth or sixth year, suggesting a lack of correlation of periodicity change and sexual maturation. Fhrther observational and experimental work is needed to solve these problems* 160

CYCLONAIAS TUBERCULATA (RAFINESQUE, 1820) (Gr. cycle » circle; Gr. naias * water nymph) (1. tubercul ■ small swelling; atus ■ possessing) Figure 23, page 151

Synonony

Obliquaria tuberculata Rafinesque, 1820. Rafinesque (1820:308). Unio verrucosus Barnes, 1823. Barnes (1823:123). Mya verrucosa (Barnes, 1823). Eaton (1826:216). Unio verrucosus purpureus Hildreth, 1828. Hildreth (1828:281). Unio tuberculosa Valenciennes, 1833. Valenciennes (1833:232). tinio tuberculatus (Rafinesque, 1820). Conrad (1836:1*3). Margarita verrucosus (Barnes, 1823). Lea (1836:16). Unio graniferous Lea. 1838. Lea (1838:69). Margarita graniferous (Lea, I838). Lea (1838:15). ftargaron verrucosus (Barnes, 1823). Lea (1852:22). Margaron graniferus (Lea, 1838). Lea (1852:22). Rotundaria tuberculata (Rafinesque, 1820). Agassiz (1852:1*8). Quadrula verrucosa (Barnes, 1823). Baker (1898:85). Quadrula tuberculata (Rafinesque, 1820). Simpson (1900:795). Quadrula grand?er aTLea, 1838). Simpson (1900:795). Quadrula granifera pusilla Simpson. 1900. Simpson (1900:795). Cyclonaias Tuberculata (Rafinesque, 1820). Ortmann & Walker f i m t w : ------Cyclonaias granifera (Lea, 1838). Grier & Mueller (1922:1*8). Cyclonaias tuberculata granifera (Lea, 1838). Baker (1928:107). Cyclonaias tuberculata compressa Baker, 1928. Baker (1928:107). Cyclonaias tuberculata tuberculata (Rafinesque, 1820). Baker (1928:1037; Type Locality

. . the Ohio and adjacent rivers; . . (Poulson, 1832:1*1*),

Ty pe Specimens

Primary types never designated. Metatype (Rafinesque-Poulson

type) A.N.S.P. 20215 (Vanatta, 1915*558).

Lake Erie Records

1823 Unio verrucosus. Barnes, p. 123.

Lake Erie 1850 Unio verrucosus. Jay, p. 68

Lake Erie

1912 Quadrula tuberculata. Clark & Wilson, p. 3.

Put-in-Bay, So. Bass Is., Ottawa Co., Ohio

1913 Quadrula tuberculata. Walker, p. 22.

Lake Erie

1919 Rotundaria tuberculata. Ortmann, p. 1*1.

La Plaisance Bay, Monroe Co., Mich.

1930 Cyclonaias tuberculata. Ahlstrom, p. U7.

Gibraltar Is., Ottawa Co., Ohio

Middle Bass Is., Ottawa Co., Ohio

Lakeside, Ottawa Co., Ohio

1932 Cyclonaias tuberculata. Goodrich & van der Schalie

(1932:11).

Lake Erie

1932 Cyclonaias tuberculata. Goodrich, p. 87.

Detroit River

Lake Erie, Monroe Co., Mich.

1937 Cyclonaias tuberculata. LaRocque & Oughton, p. 152.

Detroit River

Lake Erie

1938 Cyclonaias tuberculata. Brown, Clark & Gleissner, p.

Fishery Bay, So. Bass., Ottawa Co., Ohio

Pelee Is., Essex Co., Ont., Canada 162

19U1 Qyclonaias tuberculata. van der Schalie

Lake Erie

1953 Cyclonaias tuberculata. LaRocque, p. 90.

Lake Erie

Detroit River

195U Cyclonaias tuberculata. Langlois, p. lf>lu

Lake Erie, western end

Shell Characteristics

Size medium; compressed; outline suborbicular to subquadrate,

some old specimens becoming broadly subovate; dorsal margin straight

to slightly curved, connected to the posterior margin by a rounded

angle of 90° or more; posterior margin straight to emarginate, con­

tinuous with the ventral margin by way of a broadly rounded post-

ventral angle; ventral and dorsal margins evenly rounded, continuous,

becoming rather straight before terminating at the anterior lunule,

markedly anteriorly inequipartite, the beaks of the umbones attaining

a position just short of the anterior extremity; umbones moderately

high, rising above the hinge line and somewhat forward, becoming

inverted over the lunule; beak sculpture a series of 1$ to 18

concentric, undulate bars, the innermost seven to nine being contin­ uous from the margin of the anterior lunule to the margin of the

ligament, and having a loop or undulation on the posterior ridge and

lateral surface of the disc respectively; from this level out the bars become increasingly broken and nodular, merging into the 163 tuberculate sculpture of the disc proper; posterior ridge poorly defined, nearly flat in some Individuals; lateral sulcus usually absent, when present it is narrow, very shallow, and nearly atuber- culate; tubercles variable in size and shape but limited to the posterior two-thirds of the shell; the posterior slope usually having small and/or elongate tubercles arranged in horizontal rows which almost parallel the dorsal margin; shell solid, the heaviest of the lake dwelling naiads; periostracura brown becoming darker with age; rays absent; annular rings narrow, dark, close-set, and regular; ligament exposed, brown, short, and heavy; anterior lunule linear, width four to five in the length.

Nacre purple, occasionally nearly white in the tmbonal cavity of larger specimens; iridescent posteriorly; right valve with a single large, heavy, triangulate-serrate, pseudocardinal, surrounded by a sulcus and accompanied by two rather well developed denticles, one on either side of the sulcus; right lateral sihgle, slightly curved or straight, usually accompanied by low, lamellar ridge along its post-ventral base; interdentum broad, flat, and smooth; left pseudocardinals double, triangulate, serrate, heavy, separated by a sulcus which occasionally has a third smaller denticle arising from its base; left laterals double, straight or slightly curved; inter­ dentum well developed, broad and flat; anterior cicatrices deeply impressed, confluent; dorsal suspensories on the under side of the interdentum and pseudocardinals in both valves; pallial cicatrix well defined, markedly closer to the posterior margin; umbonal cavity com­ pressed, very deep* 16U

TABLE 23. SUMMARY OF DIMENSIONAL AMD PROPORTIONAL DATA OF SHELL MORPHOLOGY OF CYCLONAIAS TUBERCULATA (RAFINESQUE) (From: South Bay, Pelee Island, Essex Co., Ontario, Canada)

Length Hei ght Height Width Width (mm.) (mm.) Index (mm.) Index Minimum 60 52 87 26 UO

Mean 67 60 90 30 U5

Maximum 80 70 92 33 50

Range 20 18 5 7 10

Number of specimens * 9

Habitat: ...

No living specimens or complete valves of this species were

taken from Fishery Bay during this study. A single specimen was

taken by Brown, Clark, and Gleissner (1038:687) from an area "almost

one acre in extent" off Gibraltar Island across from the Ohio State

Fish Hatchery on South Bass'Island. The shallow water within this

area was searched thoroughly, but without success. Practically all

the living naiades taken here were from depths over six feet and

only a few shell fragments of C. tuberculata were found. One specimen,

which was obtained from the deep water, vand bottomed channel between

South Bass and Middle Bass Islands, was used in making the plate.

A series of nine specimens taken in July of 1957 from South Bay,

Pelee Island was employed as a source of data in constructing the

tables of dimensional and proportional variation. While these data 165

may not be typical of Fishery Bay specimens, it seems logical to

assume that they are closer than would be similar information from

stream material. The bottom at South Bay was coarse material. Stream

specimens are usually taken from or near rocky areas such as riffles

(Ortmann, 1919:60), but Call (1900:1+92) and Baker (1898:36) (1928:106)

record it from mud bottoms, as well. Whatever its habitat in Lake

Erie may be, it seems certain that this species is either rare in

Fishery Bay or that the collecting techniques employed here were in­

effective in sampling its particular habitat niche. -

Growth and Longevity

While the data presented in Table 23 were obtained from a set

of Pelee Island specimens only, the data concerning growth and

longevity were secured from five easily read specimens from several

locales in the island region. C. tuberculata. which lives in coarse

sediment bottoms, seems particularly susceptable to umbonal abrasion.

Most of the specimens collected were lacking an estimated three to

five annular rings. Only those shells which could be read with

certainty were used in this study.

The series used here appears to include the extremes of growth

rate represented by the total collection of ll+ individuals from Lake

Erie. The lowest calculated rate for the first five is 3.U milli­ meters per year for the specimen figured in this report. This same

specimen averaged 2.6 millimeters per year for the second five-year period and, upon reaching the age of 18 years, continued to grow at a 166 rate of about one millimeter a year until the time of collection at the estimated age of 23 years. A second specimen (OSU 19U8) exhibited an annual growth rate of 0.6 millimeters between the ages of 25 and

30 years. The annuli in this case were less than one millimeter apart but were quite regular and could be read easily with the aid of transmitted light. A Pelee Island specimen yielded the highest growth rate for the first five-year period. This individual averaged 5 . 5 millimeters a year during the first five year period and 1*.2 milli­ meters a year during the second five-year period. It was 11 years old when collected.

The mean rates for all five specimens are: Growth Rate (mm./yr.) 6-5 6-10 11-20 21+ Maximum Growth Period yrs. yrs. yrs. yrs. Age

Island Region li.h 3.U 1.2 1.1 31

The greatest age found was 31 years, but a heavy shell of this species from South Bay at Pelee Island was estimated at 58 years old.

The first ten annuli were read from the umbonal region which is worn smooth and without periostracum. The annular rings of the last two decades of growth, if correctly interpreted, are imbricated one upon the other, in succession and occupy a length of just under ten centi­ meters. The growth rate was estimated at about 0.5 millimeters a year at this extreme age.

Remarks

The lake form of C. tuberculata has never been given separate taxonomic recognition even though it is as distinct and striking as 167

TABLE 2lw AGE-LENGTH RELATIONSHIP OF CYCLONAIAS TUBERCULATA

Lake Erie______Number 3 Measure- Length (mm.) ^un*er ments Min. Mean Max* 1 0 2 U 9 li 12 3 5 12 15 17 U 5 15 18 21 5 5 17 22 27 6 5 20 25 32 7 5 22 28 37 8 5 2U 32 U2 9 5 27 36 U5 10 5 30 39 U8 11 5 31 Ul U9 12 U 32 U2 5U 13 U 3U UU 56 lU U 35 U6 58 15 3 36 U3 5U 16 3 37 UU 55 17 3 38 U6 56 18 3 39 U9 60 19 3 Ul 50 61 20 3 U2 51 63 21 3 UU 53 6U 22 3 U5 5U 65 23 3 U6 55 66 2U 2 U7 57 67 25 2 U8 58 68 26 2 U9 59 69 27 2 U9 60 70 28 2 50 6l 71 29 2 50 61 72 30 2 51 62 73 31 1 - 7U - AVERAGE AVERAGE LENGTH IN MILLIMETERS O OD 01 ■A o Ui ro ro N (M 00 > m H > -< m co i H o ** x m o m 01

Graph V, Age-Length Relationship of Cyclonaias tubercnlata (Rafinesque) 169 other forms which have been recognized in this manner. It appears to be about as variable within the lake as the other species studied.

Van der Schalie (19U1) concludes that the lake form is purely environ­ mental and the evidence presented here supports this inference*

It might be added that in the streams this species becomes more obese, with fewer but larger tubercles, in the downstream direction.

Specimens fitting this description have been taken with the typical compressed form at Pelee Island. This demonstrates again the peculiar large river-small stream combination of specimens fo frequently found in Lake Erie.

The synonomy of original descriptions of this species is:

Cyclonaias tuberculata (Rafinesque, 1820) Qbljquarla tuberculata Rafinesque, 1820. Unio verrucosa Barnes, 1823. Unio verrucosa purpureus Hildreth, 1828. Unio tuberculosa Valenciennes, 1833. Unio graniferous Lea, 1838. Quadrula grantfera pusilla Simpson, 1900. Cyclonaias tuberculata corapressa Baker, 1928* 170

PLEUROBEMA CORDATUM COCCINEUM (CONRAD, 1836) (Gr. pleura - siddj bema ■ step) (L. cordatus ■ heart) (L. coccineus ■ red) Figures 12, 13, lU, page 87

Synonomy

Unio rubens Menke, 1828. Menke (1828:90)* Onio coccineus Conrad, 1836. Conrad (1836:29)* Unio emeus Conrad, 1836. Conrad (l836:p. 58, fig. 1). Margarita coccineus (Conrad, 1836). Lea (1836:3^)* Unio gouldlanus Ward, 1839* Ward (1839*21*)* Margaron coccineus (Conrad, 1836). Lea (1852*35)* Quadrula coccinea (Conrad, 1836). Baker (1898:79)* Quadrula coccinea paupercula Simpson, 1900. Simpson (1900:789). Quadrula subrotunda (Lea, 1831). Sterki (1907*391) (in part)* Qrtmann (1909*203) (per errorem). Pleurobema obliquum coccineum (Conrad, 1836). Qrtmann (1911* 3^6). Quadrula emeus (Conrad, 1836). Simpson (1900:792). Pleurobema coccineum (Conrad, 1836). Ortmann (1912:263)* QuadrulaTT9iii:HBiry: coccinea--- magnalacustria------Simpson, 1911:. Simpson Pleurobema obliquum pauperculum (Simpson, 1900). Ortmann — (155^ 3' ) ' . " ------Pleurobema coccineum pauperculum (Simpson, 1900). Ortmann & Walker (1922:2k). Pleurobema cordatum pauperculum (Simpson, 1900). Ortmann (l92li:106). Pleurobema cordatum coccineum (Conrad, 1836). Ortmann (192U* — m r . ------Fusconaia subrotunda (Lea, 1831). Goodrich & van der Schalie (1932:l7T:

Type Locality

Conrad (1836:30) gives ". . . Mahoning river, near Pittsburg...11

Ortmann (1919*78) restricts the type locality to the Mahoning where it joins the Shenango forming the Beaver River at Mahoningtown, Lawrence

Co., Pa.--this being the nearest the Mahoning as such approaches

Pittsburgh, and a locality where he (Ortmann) had collected this form. 171

Type Specimens

Holotype, A.N.S.P. No. 210U (Conrad, 1836:29); Topotype,

C. M. No. 61.3907 (Ortmann, 1919:79).

Lake Erie Records

1901 Quadrula coccinea. Letson, p. 2J>2.

Niagara River at Goat Island (subfossil)

1907 Quadrula subrotunda. Sterkl, p. 391.

Lake Erie

1909 Quadrula subrotunda. Ortmann, p. 203.

Presque Isle Bay, Erie Co., Pa.

1913 Quadrula subrotunda. Walker, p. 22.

Quadrula coccinea paupercula. Walker, p. 22.

Lake Erie

1919 Pleurobema obliquum pauperculum. Ortmann, p. 8iw

Presque Isle Bay, Erie Co., Pa.

La Plaisance Bay, Monroe Co., Mich.

1920 Pleurobema obliquum pauperculum. Grier, p. 213.

Lake Erie

1920 Pleurobema obliquum pauperculum. Grier, p. 1J>1.

Lake Erie

1920 Pleurobema obliquum pauperculum. Grier, p. 18.

Presque Isle Bay, Erie Co., Pa.

1922 Pleurobema coccineum pauper Outran. Grier, p. 131.

Lake Erie 192U Pleurobema coccineum pauperculum. Ortmann, p. 106.

Lake Erie

1930 Pleurobema coccineumpauperculum. Ahlstrom, p. 1j7.

Middle Bass Is., Ottawa Co., Ohio

Lakeside, Ottawa Co., Ohio

1932 Pleurobema cordatum pauperculum. Goodrich, p. 90

Lake Erie

1932 Fusconaia subrotunda, Goodrich & van der Schalie, p

Detroit River

Pleurobema cordatum coccineum. Goodrich & van der

Schalie, p. 12.

Lake Erie

1937 Pleurobema cordatum coccineum. LaRocque & Oughton,

p. 153.

Detroit River

Lake Erie

Niagara River

Pleurobema cordatum pauperculum. LaRocque & Oughton

P. 153.

Lake Erie

1938 Pleurobema cordatum coccineum. Brown, Clark, &

Gleissner, p. 687.

Fishery Bay, S. Bass Is., Ottawa Co., Ohio

East Harbor, Ottawa Co., Ohio 173

19Ul Pleurobema cordatum pauperculum. van der Schalie.

Lake Erie

19U8 Pleurobema cordatum pauperculum. Robertson &

Blakeslee, p. 9$.

Buffalo, Erie Co., N.Y.

Niagara River at Grand Is., Erie Co., N.Y. *

Niagara River at Cuyuga Is., Erie Co., N.Y.

Niagara River at Black Creek, Welland Coi, Ont., Canada

1953 Pleurobema cordatum coccineum. Wood, p. £8.

Put-in-Bay, Ottawa Co., Ohio

1953 Pleurobema cordatum pauperculum. LaRocque, p. 97.

Niagara Falls

195k Pleurobema cordatum coccineum. Langlois, p. 15U.

Lake Erie, western end

The records of Fusconaia subrotunda (Lea, 1831) from Lake Erie most probably represent specimens of the stunted form of P. cordatum coccineum. Simpson (1900:791) noted that F. subrotunda had been reported "from Michigan and the Grand River, Ontario, but added that

"it is probable that the material from these localities is not sub- rotundus." No reasons for this statement were given. Sterki (1907:

391) in his Ohio Catalogue mentions a very small, slight form in Lake

Erie, and Ortmann (1909:203) lists "a peculiar dwarfed form" of F. subrotunda from Presque Isle Bay at Erie, Pennsylvania. Gary (1910:

183) lists the kirtlandiana (Lea) form of F. subrotunda from the Grand 17U

River in Ohio and Walker (1913:22) includes it in his list from Lake

Erie, as do Goodrich and van der Schalie (1932:12) in their compila­ tion.

This probable error was first suspected by Simpson (1900) and

first corrected by Ortmann (1919:11)* In his discussion of F. sub­ rotunda he concludes:

The records from Lake Erie given by Sterki (1907a, p. 391) and Ortmann (1919b, p. 203) do not refer to this species, but to Pleurobema obliquum pauperculum, and the same probably is true of Walker's record (1913, P. 22).

The absence of the established host fish, the Skipjack Herring,

Pomolobus chrysochloris Rafinesque, substantiates this conclusion.

The presence of the closely related Alewife, Pomolobus pseudoharengus

(Wilson), suggests the possibility of a second host fish which does live in the lake. The earliest of the naiad records in question, however, predate the first definite Lake Erie drainage .record of the

Alewife by over 30 years. Dymond (1932:32) gives the first Alewife record from Lake Erie as September of 1931. While I have not examined any of the questionable specimens it seems, on the basis of the above evidence, that Ortmann was correct. It is on this basis that the F. subrotunda records for Lake Erie are Included in the above list. 175

Fishery Bay Records

Catalogue Collection Number Date Site Collector

osu 328 IX:10:195U Outer Bay D.H.S.

osu 1127 X s23:195U Outer Bay D.H.S.

OSU 1128 X:23*195U Outer Bay D.H.S.

osu 3023 IX:20:1956 Outer Bay D.H.S.

osu 3069 IX: 20:1956 Inner Bay D.H.S.

osu 3070 IX:20:1956 Inner Bay D.H.S.

Shell Characteristics

Size small to medium; subinflated; outline variable but usually subtriagonal and almost always lacking any well-defined marginal angles; dorsal margin distinctly curved, becoming the posterior margin with only the f&ihtest suggestion of an angle in a very few specimens; post-basal angle smoothly and broadly rounded; ventral margin gently curved to straight to slightly emarginate in a few individuals, con­ tinuous with the anterior margin which curves strongly upward, usually becoming straight before terminating at the level of the lunule; markedly anteriorly inequipartite, the beaks nearly reaching the anterior extremity in most specimens; umbones high, directed for­ ward and upward, sculpture a series of 3-h concentric trapezoidal bars, the inner one or two of which are complete, the outer two or three each being represented by a rather large undulate swelling on the posterior ridge; surface of the disc without ornamentation; posterior ridge broadly rounded) some relatively high specimens with

a wide, very shallow lateral sulcus; posterior slope not sulcate

except near the region of the beaks; shell solid; periostracum usually

dark brown to black but occasionally reddish brown or yellow-brown;

rays when present, narrow, gray-green, and usually confined to the

lateral slope just anterior to the posterior ridge; rays, when

present in dark shells, can be seen with the use of transmitted light

and are usually best developed just beneath the umbones; annual

rings dark, narrow, and well defined; ligament dark brown, short, moderately heavy, exposed, lunule varies from linear in compressed

specimens to cordate in obese specimens, occasionally as wide as long*

Nacre usually white but sometimes light orange, cream, or pink; iridescent in the region of the post-basal angle; right pseudo­

cardinal immediately beneath the beak, single, large, triangulate,

serrate, surrounded by a sulcus which may be flanked on its outer margins by a pair of small denticles, one below the lunule and one

subtending the interdentum; right valve with a single, well-developed,

curved lateral, nearly always accompanied by a supplemental lateral paralleling its ventral surface; this ventral lateral is. rarely large as the dorsal tooth; interdentum well developed, flat, elongate;

left pseudocardinals double, serrate, separated by a sulcus; posterior tooth largest, triangulate, subtending a broad flat interdentum; anterior pseudocardinal relatively small, narrowly triangulate to lamellar, located immediately beneath the lunule, nearly paralleling the margin at that point, and making a right angle with the major TABLE 25. SUMMARY OF DIMENSIONAL AND PROPORTIONAL DATA OF SHELL MORPHOLOGY OF PLEUROBEMA CORDATUM COC­ CINEUM (CONRAD)

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index Minimum 33 30 78 18 U5

Mean U8 3 9 83 2h 50

Maximum 58 U5 91 26 55

Range 25 15 13 8 10

TABLE 26. DIMENSIONAL AND PROPORTIONAL DATA OF PLEUROBEMA CORDATUM COCCINEUM (CONRAD) RELATED TO LENGTH (SIZE) GROUP

Length Number Mean Mean Mean Mean Mean Group of Length Height Height Width Width (mm.) Specimens (mm.) (mm.) Index (mm.) Index

0-9 0 --- - -

10-19 0 - - - - mm

20-29 0 - --- -

30-39 1 33 30 91 18 55

U0-U9 2 U7 39 83 2U 50

50-59 3 52 U3 80 25 U8 178

axis of the laterals; anterior cicatrices very deeply impressed, dis­

tinct or nearly so, posterior cicatrices moderately inpressed, the posterior retractor scar just beneath the posterior termination of

the laterals; dorsal suspensory scars beneath the interdentum and posterior pseudocardinals in both valves; pallial line distinctly

impressed anteriorly, markedly less so in the post-basal region,

equidistant from the margin throughout; umbonal cavity rather shallow, compressed.

Habitat

Wood (19f>3:5>8) recorded P. c. coccineum "in a very poorly sorted

silt," and this seems to be its habitat in Fishery Bay. Specimens from both the inner and outer bay areas came from poorly sorted sub­ strates which were predominately a loose, somewhat flocculent silt.

This is surprising in view of its being associated with riffles rather than the pooled areas of streams in central Ohio. Ortmann (1919:81) found this species in and below riffles. Baker (1928:115) records it from gravel and sand and further noted its being found buried in sand bars. All these agree ifith my own observations which were made in the streams. Ortmann's Presque Isle Bay specimens (1919:81;) x*ere col­ lected in a few feet of water from a pure sand bottom. It may be that this species has a different host in the lake or that the habits and/or habitat of the host fish, if it be the same species, may be different in the lake environment. The host fish Is not known, and it seems that the answer to this question might hold the answer to the habitat distribution problem. 17 9

Growth and Longevity

The oldest Individual from the study area was found to be

forty years of age. Its average growth rate was 1.3 millimeters a

year during the forty-year period, and varied from a rate of 2,7

millimeters a year for the first five years of life to 0.6 millimeters

a year for its last five years of growth.

The mean rates for specimens from the two bay areas yielding

material are:

Growth Rate (mm./yr.) 0^5 6-10 11-20 21+ Maximum Growth Period yrs. yrs. yrs. yrs. Age Approx. Habitat Depth Substrate

Inner Bay 5* silt 3.8 2.6 1.9 — 23

Outer Bay 20 * silt 2.8 2.U 1.3 0.6 UO

Since the substrate was quite similar in both areas, this

material lends itself to a test of the effects of depth upon growth

rate with at least one factor more or less controlled. Assuming

other factors (except those affected by depth) to be essentially the

same, it is demonstrated that the growth rate varies inversely with

depth.

Remarks

The Pleurobema cordatum complex has been one of the most diffi­

cult groups of Mississippi mussels with which the naiadologist has 180

TABLE 27. AGE-LENGTH RELATIONSHIP OF PLEUROBEMA CORDATUM COCCINEUM

Inner Bay Outer Bay Number Number Annulus Measure­ Length (mm.) Annulus Measure­ (Length (mm.) Number ments Min. Mean Max. Number ments Min. Mean Max.

1 0 & «• 1 2 u u U 2 2 6 8 10 2 2 6 7 8 3 2 10 13 15 3 3 8 9 10 U 2 12 16 20 U U 10 11 12 5 2 15 19 22 5 u 13 lU lU 6 2 18 22 25 6 u 16 17 17 7 2 22 25 28 7 u 18 19 20 8 2 26 28 30 8 u 20 22 22 9 2 28 30 32 9 u 22 2U 25 10 2 30 32 3U 10 u 25 26 27 11 2 32 3U 36 11 u 27 28 29 12 2 35 37 38 12 u 29 30 31 13 2 38 39 39 13 u 30 31 33 lU 2 UO U2 Ul 1U u 32 33 35 15 2 Ul U3 UU 15 3 33 3U 36 16 2 U2 UU U6 16 3 3k 35 37 17 2 UU U6 U8 17 3 35 36 38 18 2 U6 U8 U9 18 3 36 37 39 19 2 U8 U9 50 19 3 37 38 UO 20 2 50 51 52 20 3 37 39 Ul 21 1 - 53 -■ 21 3 38 UO U2 22 1 - 55 - 22 3* ; 38 Ul U2 23 1 - 57 - 23 3 39 U3 UU 2U 3 39 UU U5 25 2 UO U3 U5 26 2 UO U3 U6 27 2 Ul UU U6 28 2 U2 U5 U7 29 2 U3 U5 U7 30 2 UU U6 U8 31 2 UU U6 U8 32 1 - U5 - 33 1 - U6 - 3k 1 - U7 _ 35 1 - U8 •m 36 1 - U9 - 37 1 - U9 - 38 1 a a 50 mm 39 1 - 50 UO - 51 - average length in millimeters O T 0 4 20 60 0 rp I AeLnt eainhpo luoeacrau nwim(Conrad), Age-LengthGraph VI,Relationship of Pleurohema cordatum 4 8 12 SIAE AE N YEARS IN AGE ESTIMATED 16 20 24 INNER BAY * 28 32 640 36 OUTEI: BAY 182

had to deal. As with most of these complexes the forms were origin­

ally thought to be, and described as, distinct species.

The first insight into the relationships of the group was made

by Ortmann (1910:11?) in a footnote:

PL obliqua. pyramidata ^and also plena (LeaJ[7 form a natural group by themselves and probably are one and the same species. P. pyramidata is only an extreme variation of PI. obTiqua, with which it occurs, while coccinea is a good ecological Variety, which, however, runs into obiiqua at certain localities*

In his Pennsylvania Monograph, Ortmann (1919:69) grouped six

forms as subspecies of P. obliquum (Lamarck, 1819). The lake form was

included as the subspecies P. c. pauperculum (Simpson, 1900). Several years later it was concluded (Lea, 1829:1*22) (Ortmann & Walker, 1922:

21) that obliquum Lamarck, 1819, was unidentifiable and that the name

cordata Rafinesque, 1820, was identifiable and available. Thus it was

that the form in Lake Erie became known as Pleurobema cordatum pauper­ culum.

A very accurate description of the lake form is given by

Goodrich (1932:90):

A form in Lake Erie is called P. cordatum pauperculum (Conrad), scarcely a fortunate name since the moliuSk is not much smaller than the form of the streams, and is rougher and more swollen.

The above comparison of size reveals that the stream specimens in mind were very likely from northern streams, probably Michigan tributaries of the lake, where the size is relatively small. The rougher appearance of the shell is due to crowded annular rings, a . lake characteristic, and the "more swollen" condition is the large river feature present in so many Lake Erie species. LaRocque and Oughton (1937:1E>3) listed both P. c. pauper culm and the headwater form, P. c. coccineum, from Lake Erie. The follow­ ing year Brown, Clark, and Gleissner (1938s687) referred to the lake specimens as P. c. coccineum, presumably including pauperculum in

its synonomy. Van der Schalie (19U1) includes pauperculum in his list of environmental lake forms and later students have, for the most part, followed van der Schalie's example.

The material presently available is too limited to determine the nature of this group in Lake Erie. The data collected from the

31 specimens at hand indicate, however, the presence in the lake of specimens having the proportions, as well as some of the other characteristics, of several of the recognized subspecies of this complex. It seems best at present to refer to the Lake Erie popula­ tion as simply Pleurobema cordatum ssp., thus recognizing the species and indicating the existence of subgroups. 18U

ELLIPTIC) DILATATUS (RAFINESQUE, 1820) (Gr. ellipsis “ ellipse) (L. dilatatus ■ to enlarge) Figure 17, page 109

Synonomy

Unio nasutus* Lamarck, 1819. Lamarck (1819:75)* Unio dilatatus Rafinesque, 1820. Rafinesque (1820:297). Unio gibbosus*"Barnes, 1823. Barnes (1823:262). Unio mucronatus Barnes, 1823. Barnes (1823:226). Mya gibbosa (Barnes, 1823). Eaton (1826:220). Mya mucronata (Barnes, 1823). Eaton (1826:220). Unio arcus Conrad, 183U- Conrad (I83I4.S3U0)• Unio arctatus Conrad, 183k. Conrad (I83k:3k0). Unio arciior Lea, 183k. Lea (l83k:10). Uniio torulosus Ferussac, 1835. Ferussac (1835:28). Margarita gibbosus (Barnes, 1823). Lea (1836:38). Margarita arcus (Conrad, 183k). Lea (1836:38). Margarita arciatus (Conrad, 183k). Lea (1836:38). Margaron gibbosus (Barnes, 1823). Lea (1852:38). Margaron arcus (Conrad, 183k). Lea (1852:38). Margaron arctlor (Lea, 183k). Lea (1852:38). Margaron arctatus (Conrad, 183k). Lea (1852:38). Unio lazarus Lea, 1852. Lea (1852:15). Unio subgibbosus Lea, 1857. Lea (1857:169). Unio rufus Lea,‘1857. Lea (1857:171). Margaron subgibbosus (Lea, 1857). Lea (1870:61). Margaron rufus (Lea, 1857). Lea (1870:61). Unio gibbosus armathwaitensis Wright, 1898. Wright (1898:123). Unio gibbosus subgibbosus Lea, 1857. Simpson (1900:70k). Unio gibbosus arcus Conrad, 183k. Simpson (1900:70k). Unio gibbosus delicatus Simpson, 1900. Simpson (1900:70k). Elliptio gibbosus (Barnes, 1823). Ortmann (1911:3kk). Elliptio dilatatus (Rafinesque, 1820). Utterback (1915:201). Elliptio dilatatus stibgibbosa (Lea, 1857). Utterback (1915: §02)7 Elliptio dilatata delicata (Simpson, 1900). Utterback (1915: 103)7 Elliptio dilatatus sterkii Grier, 1918. Grier (1918:9).

lame preoccupied by Unio nasutus Say, 1817. 185

Type Locality

The descriptive account, given by Rafinesque (1820s297), according to Poulson's translation (1832:25), does not mention the site of collection. The translated title of the work "Monograph of the Bivalve Shells of the River Ohio," in the absence of any other designation, fixes the Ohio River as the type locality.

Type Specimens

Holotype never designated. Metatype (Rafinesque-Poulson type)

A.N.S.P. No. 202U8 (Vanatta, 1915:555).

Lake Erie Records

1861 Unio gibbosus. Bell, p. 1*6.

Niagara River, ancient bed (sub-fossil), Welland Co.,

Ontario, Canada

1901 Unio gibbosus. Letson, p. 2£l.

Niagara River at Goat Is.

1907 Unio gibbosus. Sterki, p. 392,

Lake Erie

1909 Unio gibbosus. Ortmann, p. 203.

Presque Isle Bay, Erie Co., Pa,

1910 Unio gibbosus. Gary, p. 183.

Cedar Point, Erie Co., Ohio

1912 Unio gibbosus. Clark and Wilson, p. 38.

So. Bass Is., Ottawa Co., Ohio 186

1913 Unio gibbosus. Walker, p. 5>.

Lake Erie

1918 Elliptio dilatatus sterkli. Grier, p. 9.

Presque Isle Bay, Erie Co., Pa.

1919 Elliptio dilatatus sterkii. Ortmann, p. 102.

Lake Erie off Presque Isle, Erie Co., Pa.

Port Colbourne, Welland Co., Ont., Canada

Cedar Point, Erie Co., Ohio

La Plaisance Gay, Monroe Co., Mich.

1920 Elliptio dilatatus sterkii. Grier, p. 18.

Presque Isle Bay, Erie Co., Pa.

1920 Elliptio di latatus sterki i. Grier, p. 1J>1.

Lake Erie

1921 Unio gibbosus. Coker et al., p. 100.

Put-in-Bay, Ottawa Co., Ohio

1922 Elliptio dilatatus sterki1. Grier, p. 131.

Lake Erie

192U Elliptio dilatatus sterkii. Ortmann, p. 106.

Lake Erie

1930 Elliptio dilatatus sterkii. Ahlstrom, p. k7»

Rattlesnake Is., Ottavra Co., Ohio

1932 Elliptio dilatatus sterkii. Goodrich & van der Schalie,

p. 11.

Lake Erie 187

1937 Elliptio dilatatus sterkii. LaRocque & Oughton, p. 152.

Lake Erie

Niagara River

1938 Elliptio dilatatus. Brown, Clark & Gleissner, p. 687.

Fishery Bay, So. Bass Is., Ottawa Co., Ohio

Pelee Is., Essex Co., Ont., Canada

19U1 Elliptio dilatatus. van der Schalie.

Lake Erie

19U2 Elliptio dilatatus sterkii. Shelford & Boesel, p. 182.

Lake Erie, western

19U8 Elliptiodilatatus sterkii. Robertson& Blakeslee, p. 95*

Long Beach, Ont., Canada

Low Banks, Ont., Canada

Niagara River at Black Creek, Welland Co., Ont., Canada

Niagara River at Cayuga Is., Niagara Co., N.Y.

Niagara River at Grand Is., Erie Co., N.Y.

1953 Elliptiodilatatus. Wood, p. 58.

Lake Erie, western basin

1953 Elliptiodilatatus sterkii. LaRocque, p. 91.

Lake Erie

Presque Isle Bay, Erie Co., Pa.

1953 Elliptiodilatatus. Langlois, p. 15U»

Lake Erie, western end

This species was known to several generations of naiadologists as Unio gibbosus Barnes, 1823. Utterback (1915*201) recognized it as 188

U. dilatatus Rafinesque, 1820, and his interpretation was supported by

Ortmann and Walker (1922:30). Grier (1918:9) provided the subspecific name sterkii for the Lake Erie population. This designation was generally used until Brown, Clark, and Gleissner (1938:689) demon­ strated, with Lake Erie naiades of this species, that

According to height, all our specimens (those from the river as well as the lake) belong to the stream variety while according to obesity they would all become sterkii. We seriously doubt the validity of varieties based upon such variable characters.

Van der Schalie (19U1) also recognized sterkii as an environ­ mental variant and there has followed a general tendency to drop the use of the trinomial.

Fishery Bay Records

Catalogue of Collection Number Date Specimens Site Collector

OSU 167 III: 3:19$U 1 Inner Bay D.H.S.

OSU 29$ VII:26:19$U 1 Inner Bay D.H.S.

OSU 3 0 1 and 302 VIII: 8:19$U 2 Inner Bay D.H.S.

OSU 697 to 699 IX:21:195U 3 Inner Bay D.H.S.

OSU 1332 to 133U IX:21:19$U 3 Inner Bay E. Kindt & R. Zura

OSU 1136 to 1139 X:23:19$U h Inner Bay D.H.S.

OSU l$hk 111:22:19$$ 1 Inner Bay D.H.S.

OSU 1611 to l6Uj. V I O 7:19$$ h Inner Bay E. Miller and D.H.S. 189

No. Catalogue of Collection Number Date Specimens Site Collector

OSU 1619 to 1635 VII: 8:1955 17 Inner Bay E. Miller and D.H.S.

OSU 3072 to 3073 IX:20:1956 2 Inner Bay D.H.S.

Shell Characteristics

Size small to medium; moderately compressed; outline elongate elliptical, occasionally becoming arcuate with age; dorsal and posterior margins a continuous gentle curve or nearly so; post-basal angle simple in young specimens, becoming distinctly biangulate in older individuals; ventral margin slightly convex in young specimens, usually becoming straight or somewhat emarginate with age; anterior margin fully rounded, terminating just anterior to the lunule forming a small marginal concavity; umbones low, scarcely rising above the hinge line; distinctly inequipartite anteriorly; beaks sculpture a series of three to five rather heavy slightly undulate concentric trapezoids, the base of each trapezoid being nearly parallel to the growth lines, the basal angles sharply formed on the posterior ridge and anterior lateral surfaces respectively, the sides of the trapezoid converging on the hinge line just medial to the tips of the beaks; posterior ridge rounded but well-defined, usually becoming decurved and biangu­ late with age; arcuate specimens producing a very shallow lateral sulcus; surface of disc without tubercles, flutings, or corrugations; shell subsolid to solid; periostracum of one to two year old specimens 190 bright yellow with fine green rays and a purplish cast in the region

of the beak sculpture; three to five year old individuals olivaceous with dark brown or black annuli, and rays difficult to see except with the aid of transmitted light; periostracum of adults brown to brownish black, and rarely with rays, surface coarse textured with crowded, narrow, dark annuli; ligament moderately heavy, dark brown, elongate, and exposed; lunule linear length two to three times the width.

Nacre usually a deep purple, blue, or lavender and rarely white; some young specimens with inner pallial area light brownish- blue and the margin cream to white; slightly iridescent posteriorly; right pseudocardinal single, triangulate serrate, separated from the interdentum, and hinge line by a sulcus; a small denticle usually present on the hinge line beneath the lunule; right lateral, single, straight to gently curved, obliquely striate above and below and occasionally accompanied by a low supplemental lateral along its post-ventral base; interdentum narrowly elongate, poorly developed; left pseudocardinals double, triangulate, serrate, separated by a serrate sulcus; anterior tooth subtending the hinge line below the lunule; posterior tooth adjacent to the interdentum and dorsal margin just posterior to the level of the beaks; left laterals double obliquely, striate within; interdentum, if developed, undulate elongate; anterior cicatrices deeply impressed, distinct, posterior cicatrices rather deeply impressed, confluent; dorsal suspensories on 191

TABLE 28. SUMMARY OF DIMENSIONAL AND PROPORTIONAL DATA OF SHELL MORPHOLOGY OF ELLIPTIO DILATATUS (RAFINESQUE)

Length Height Height Width Width (mm.) (mm.) Index (mm.) Index Minimum 12 7 1+7 3 23

Mean 1+5 32 51 22 33

Maximum 88 1+3 58 30 39

Range 76 36 11 27 16

TABLE 29. DIMENSIONAL AND PROPORTIONAL DATA OF ELLIPTIO DILATATUS (RAFINESQUE) RELATED TO LENGTH (SIZE) GROUP

98SSSS9 Length Number Mean Mean Mean Mean Mean Group of Length Height Height Width Width (mm.) Specimens (mm.) (mm.) Index (mm.) Index

mm 0-9 0 . - ---

10-19 1+ 15 8 53 1+ 27

20-29 0 - mm -- -

30-39 2 32 15 1+8 9 27

1+0-U9 2 1+6 23 50 15 32

50-59 0 - - mm --

60-69 8 67 35 52 25 37

70-79 18 75 38 51 26 35

80-89 1+ 81+ 1+1 1+9 29 31+ 192 underside of interdentum in each valve; pallial line distinctly im­ pressed, pallial margin widest at the posterior extremity; umbonal cavity very shallow.

Habitat

During the first year of collecting only U 4 specimens of

Elliptio dilatatus were taken in spite of a seiche of major proportions.

This seemed unusual in view of Brown et al. (1938:687) having found this species to be the most abundant (13U specimens) in their Fishery

Bay collections. The area which Brown et al, worked lay just off

Gibraltar Island in the inner bay. This area, when dredged, had yielded few naiades but had given evidence of a substrate of large rocks. Diving established that the bottom was, in fact, a firm, non-shifting sand but was strewn with a number of large boulders.

Collections were made from this zone by diving during two rare days of relatively quiet, clear water. Twenty-one individuals were obtained in this manner, and more could have been obtained had the weather continued fair.

The host fish of Elliptio dilatatus is not known, but the life history of a closely related species, E. complanatus (Dillwyn), has been studied by Matteson (19U8). A number of fish were tested by

Matteson but only the Yellow Perch, Perea flavescens, proved to be a successful host. The Yellow Perch is a very common species in Lake

Erie and may also serve as host to E. dilatatus. LAKE ERIE

HUNDRED FEET Peach Point

• •

• •

GIBRALTAR ISLAND

SOUTH BASS ISLAND Oak Point

Map XT. Distribution Records of Elliptio dilatatus (Rafinesque) and Qyclonalas tuberculata (Raflnesque) in Fishery Bay0

• Elliptio dilatatus (Rafinesque).

Orclonaias tuberculata (Rafinesque).

vo 19h

Growth and Longevity

Rates were calculated for a series of three specimens from the

deep lake for purposes of comparison with the rates computed for the

Inner bay material.

Growth Rate (mm./yr.) 0-5 6-10 11-20 21+ Maximum Growth Period yrs. yrs. yrs. yrs. Age

Approx. Habitat Depth Substrate

Inner Bay 6'-l5’ sand, rocks 8.U 3.U 1.1 1.0 30

Deep Lake 30'-35' sand, gravel 5.6 2.2 1.1 1.1 35

The deep lakematerial was dredged from thechannel between

South Bass and MiddleBass Islands. Since the bottoms are predom­

inantly sand in both cases this factor might be considered of minor

importance here in rate determination. "Compensatory growth" is

exhibited by the deep water forms which approach, but never quite

attain, the length of the Fishery Bay individuals.

Remarks

The "Spike" or "Lady Finger" of the clammers appears to be

not only the most abundant but one of the fastest growing of the

Fishery Bay Unioninae. This may be more apparent than real, however,

in view of several collecting experiences noted in this report. This particular group of naiades consists of species which are characteris­

tic of coarse bottoms and rapid currents. While these conditions are 195

TABLE 30. AGE-LENGTH RELATIONSHIP OF ELLIPTIO DILATATUS

______Inner Bay______Deep Lake Number Number Annulus Measure- Length (mm.) Annulus Measure- (Length (mm.) Number ments Min. Mean Max. Number ments Min. Mean Max.

1 8 5 10 15 1 1 - 10 - 2 26 13 20 25 2 2 16 17 17 3 29 ' 21 29 36 3 3 19 20 21 h 29 25 37 aa a 3 23 2a 2a 5 .*■28 29 U2 51 5 3 27 28 28 6 28 3k U7 57 6 3 30 31 31 7 28 38 51 6U 7 3 32 33 3a 8 27 U3 5U 63 8 3 3a 36 38 9 27 1x6 56 66 9 3 35 38 a i 10 27 U8 59 70 10 3 36 39 a2 11 27 50 61 73 11 3 38 ao a3 12 27 52 63 76 12 3 39 a i aa 13 26 53 65 77 13 3 ao a2 a7 1U 23 55 66 79 ia 3 a i a3 ae 15 20 58 67 80 15 3 a2 aa a9 16 18 59 67 81 16 3 aa a6 5o 17 17 60 68 89 17 3 a5 a7 51 18 16 62 69 82 18 3 a6 as 52 19 1U 63 69 78 19 3 a7 a9 53 20 13 6U 70 79 20 3 as 50 5a 21 10 68 72 80 21 3 a9 51 55 22 9 69 73 81 22 3 5o 52 56 23 6 70 7U 78 23 3 51 53 57 2U U 71 75 79 2a 3 52 5a 57 25 3 72 75 80 25 2 5a 56 58 26 3 to 76 81 27 2 75 79 82 28 2 76 80 8U 29 1 - 85 - 30 1 - 87 - average length in millimeters 20 60 40 80 0 Graph VII, Age-Length Relationship of Elliptio dllatattta (Rafinesque). dllatattta Elliptio of Relationship Age-Length VII, Graph 4 8 SIAE AE N YEARS IN AGE ESTIMATED 12 20 2416 DEEP 28 LAKE INNEF BAY 32 197

associated with the shallow, easily studied riffle areas in streams,

this is not always true in a body of water such as Lake Erie* There

has yet to be devised a collecting device which the biologist can

conveniently use to secure samples from rocky bottoms tinder deep

water. The data at present indicate the Unioninae to be the least

abundant subfamily of naiades in the Fishery Bay area but this may be

a reflection of the inefficiency of collecting techniques rather than

an accurate estimate of relative population size.

The synonomy of described names of this species includes:

Elliptio dilatatus (Rafinesque, 1820). Unio nasutus Lamarck, 1819. Unio dilatatus Rafinesque, 1820 Unio gibbosus Barnes, 1823* Unio mucronatus Barnes, 1823. Unio arcus Conrad, 183U. Unio arctatus Conrad, I8 3 U. Unio torulosus Ferussac, 1835* Unio arctior Lea, I8 3 U. Unio lazarus Lea, 1852. Unio subgibbosus Lea, 1857* Unio ruius Lea, 1857* Unio gibbosus armathwaitensis Wright, 1 8 9 8 . Unio gibbosus dellcatus Simpson, 1900. EiliptTo dilatatus sterkii Grier, 1918.

The length of the above list of descriptions attest the variability of this species. SUMMARY

The naiad subfamily Unioninae is represented in Fishery Bay

by nine species or subspecies of six genera:

Subfamily Unioninae

Fusconaia flava flava (Rafinesque, 1820). Fusconaia ilava undata (Barnes, 1823). Arriblema plicata plicata (Say, 1817). Amblema plicata peruviana (Lamarck, 1819). Quadrula quadrula quadrula (Rafinesque, 1820). Quadrula pustulosa (Lea, 1831). Cyclonai'as tuberculata (Rafinesque, 1820). Pleurobema cordatum coccineum (Conrad, 1 8 3 6 ). Elliptio~~dilatatus (Rafinesque, 1820).

The evidence indicates this fauna gained access to the Lake

Erie basin from the lower Ohio River by way of the Maumee-Wabash

River glacial outlet during the time of glacial Lake Maumee. This migration route had a number of large river characteristics which were sufficient to enable some large river species of fish and naiades to make the migration. Some of these large river mussels, i.e.,

F. f. undata, A. £. peruviana, and others, persist in the lake today.

Lake Erie has a combination of large river and small stream characteristics. This fact in conjunction with its being, or having been, accessible to both faunal elements, has resulted in the present unusual combination of headwater and large river forms in the lake fauna. Those naiad subspecies assembled in the lake basin have inter­ graded. This intergradation is evident in lake populations of

198 1 9 9

Fusconaia flava and Amblema plicata and Is suggested In the case of

Pleurobema cordaturn.

The growth rate of the lake-dwelling naiades investigated varies with the age and habitat. The most rapid growth rate for each species occurred during its first five years of growth. The highest calculated rate was the average of ten millimeters a year for a five-year old Quadrula quadrula (Rafinesque). The older the ' individual becomes the slower becomes its growth rate, decreasing, in some instances, to less than half a millimeter a year.

Relatively strong, persistent, shore currents were associated with rapid growth. Locations having such currents were identified by shallowness and coarseness of the substrates. The slowest growing indiv­ iduals were taken from silt bottoms in deep water while individuals from the shallows on gravel bars exhibited the highest rates of growth.

The maximum age in the case of all species, except those of the genus Quadrula, was over 20 years. The oldest naiad from the study area was a I4.O year old specimen of Pleurobema cordatum coccineum.

The two species of Quadrula are represented from Fishery Bay by only three specimens each and material from elsewhere in Lake Erie in­ dicates a longevity close to, if not in the same general range as, the others. LITERATURE CITED

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I, David Honor Stansbery, was born at Upper Sandusky, Wyandot

County, Ohio, on May 5* 1926, I reoeived my secondary school education

in the public schools of Upper Sandusky* The period of time from July,

1944, to July, 1946, was spent on active duty with the United States

Navy, I received my undergraduate degree, Bachelor of Science, from

The Ohio State University in 1950* This was followed by a summer's

study at Western Heserve University and three years’ teaching in the public secondary schools of Plymouth, Ohio, and of Put-in-Bey, Ohio*

In 1953 1 was granted the Master of Science degree from the Franz

Theodore Stone Institute of Hydrobiology of The Ohio State University*

In 1953 I was appointed Senior Conservation Fellow at the Stone Insti­ tute and continued under this appointment until the summer of 1955*

Since that time I have been associated with the Department of Zoology and Xntomology as graduate assistant and as instructor while completing the requirements for the degree Doctor of Philosophy*

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