Patterns of Diurnal Vertical Distribution and Dispersal

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OEAS Theses and Dissertations Ocean, Earth & Atmospheric Sciences

Spring 1986

Patterns of Diurnal Vertical Distribution and Dispersal- Recruitment Mechanisms of Decapod Crustacean Larvae and Postlarvae in the Chesapeake Bay, Virginia and Adjacent Offshore Waters

Robert Copeland Maris Old Dominion University

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Recommended Citation Maris, Robert C.. "Patterns of Diurnal Vertical Distribution and Dispersal-Recruitment Mechanisms of Decapod Crustacean Larvae and Postlarvae in the Chesapeake Bay, Virginia and Adjacent Offshore Waters" (1986). Doctor of Philosophy (PhD), dissertation, Ocean/Earth/Atmos Sciences, Old Dominion University, DOI: 10.25777/h953-fj74 https://digitalcommons.odu.edu/oeas_etds/142

This Dissertation is brought to you for free and open access by the Ocean, Earth & Atmospheric Sciences at ODU Digital Commons. It has been accepted for inclusion in OEAS Theses and Dissertations by an authorized administrator of ODU Digital Commons. For more information, please contact [email protected]. PATTERNS OF DIURNAL VERTICAL DISTRIBUTION AND DISPERSAL-RECRUITMENT MECHANISMS OF DECAPOD CRUSTACEAN LARVAE AND POSTLARVAE IN THE CHESAPEAKE BAY, VIRGINIA AND ADJACENT OFFSHORE WATERS

by Robert Copeland Maris B.S. December 1975, Texas ASM University M.S. May 1980, University of Southern Mississippi

A Dissertation Submitted to the Faculty of Old Dominion University in Partial Fulfillment of the Requirements for the Degree of

DOCTOR OF PHILOSOPHY OCEANOGRAPHY

OLD DOMINION UNIVERSITY May, 1986

Approved by:

ohn R. McConaugha (Dire«#or)

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT

PATTERNS OF DIURNAL VERTICAL DISTRIBUTION AND DISPERSAL-RECRUITMENT MECHANISMS OF DECAPOD CRUSTACEAN LARVAE AND POSTLARVAE IN THE CHESAPEAKE BAY, VIRGINIA AND ADJACENT OFFSHORE WATERS

Robert Copeland Maris Old Dominion University, 1986 Director: Dr. John R. McConaugha

Larval dispersal and subsequent postlarval recruitment are extreme

ly significant processes affecting the maintenance of ecologically and

economically important populations of decapod crustaceans. Vertical

positioning in the water column plays a major role in the particular

strategies of retention or expulsion with immigration.

The present study was undertaken to investigate variations in ver

tical distribution according to temporal (diurnal), spatial (estuarine,

transition, oceanic), ontogenetic (larval stages, postlarvae) and vari

ous environmental factors (especially light, temperature, salinity and

tides). Also, effects of vertical positioning on dispersal-recruitment

were examined.

Three stations were established for the present study: York River

mouth (estuarine) (37°12’N, 76°16'W); Chesapeake Bay mouth (transition)

(36° 58'N, 76°07’W); Chesapeake Light Tower (offshore) (35° 54’N, 75°

43*W). Each station was occupied for a continuous 72 hour period in

late summer, and quantitative plankton samples were taken every three

hours from the following depths: neuston (0.10-0.15 m), 1 m, 3 m, 6m ,

epibenthic (10.7-12.8 m). The collection consisted of 375 samples.

A total of 41 species, 160 developmental stages and an estimated

6,000,000 specimens were obtained, with 86% of the total catch coming

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. from the offshore location. True crabs (Brachyura) accounted for 53% of

the species, 50% of the stages and 92.42% of the total catch. The most

commonly collected species were Callinectes sapidus (87.40% of the

total), Uca spp. (3.45%), and Pinnixa chaetopterana (1.74%).

Of the 160 developmental stages, 56 were found in sufficient quan

tities for analysis. Fifteen different distributional groups were estab

lished based on comparisons of Spearman rank correlation coefficients

with depth.

Results indicated that proximity to the estuary greatly affects

vertical positioning. Overall day-night mean depths for collective

specimens were: York River mouth, 5.96-4.24 m; Chesapeake Bay mouth,

7.49-3.19 m; offshore, 1.86-1.41 m. Light was proposed to be the major

factor affecting distribution, with temperature, salinity and tidal

cycles having little effect.

Six dispersal-recruitment patterns were established for collected

genera based on vertical and spatial distributions of larvae and post

larvae compared with adult habitats: retained estuarine (Neopanope,

Palaemonetes, Panopeus). retained estuarine-transitional (Callinassa,

Pinnixa, Pinnotheres, Upogebia), retained transitional-nearshore

(Euceramus. Hexapanopeus, Pagurus), retained offshore (Emerita, Libinia,

Ovalipes), expelled with estuarine spawning (Uca) and expelled with

transitional spawning (Callinectes).

Hypothesized dispersal-recruitment mechanisms included: mainte

nance at a given depth without diurnal vertical migration, active ver

tical migration to a depth of zero net motion, and varying degrees of

vertical migration throughout the water column.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGEMENTS

I will always be indebted to my thesis advisor the late Dr. A.

Geoffrey Fish, Department of Biology, University of Southern Mississip

pi, Hattiesburg, Mississippi for arousing my interest in plankton. His

unique sense of humor brightened many dark days.

I am extremely grateful for the time and help given to me by my

dissertation committee: Drs. John R. McConaugha (Chairman), Anthony J.

Provenzano, Jr., David L. Feigenbaum and Michael H. Prager, all of the

Department of Oceanography, Old Dominion University, Norfolk, Virginia,

and Dr. Charles E. Epifanio, College of Marine Studies, University of

Delaware, Lewes, Delaware. I also appreciate the assistance supplied by

my guidance committee: Drs. Provenzano (Chairman), McConaugha and

Feigenbaum.

Field collections would not have been possible without the expert

help, advice, time and effort given by the crew of the R/V Linwood

Holton (berthed at the Naval Amphibious Base - Little Creek) for the

entire 216 hours of sampling: Captains Robert N. Bray and James D.

Padgett, and Engineer Nelson C. Griffin. Special thanks is given to

Emily Deaver for helping with all three phases of sampling.

The following people assisted with sampling for various periods of

time during the 72-hour bay mouth study, 19 August - 1 September 1983:

Erik Barth, Sandy Booth, Emily Deaver, Rick Hall, Beth Hester (entire 72

hours), Bruce Hill, Dr. Donald Johnson, Mike Kelly, Joung Kim, Ken

Kimidy, Rebecca Lovingood, Yvonne Maris, Les Parker, Mario Paula,

Florence Roessler, Phil Sadler, Ray Sawyer and Larry White. Yvonne

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Maris helped load the gear prior to sampling, transported people and

food, and assisted in sample washing along with Jim Pletl.

The following individuals helped with sampling for various periods

of time during the 72-hour York River mouth study: Paul Cheek, Emily

Deaver, Chris Frye (entire 72 hours), Joung Kim, Yvonne Maris, Michael

Mutua (entire 72 hours), Jean Pletl, Jim Pletl and Lyle Varnell. John

Keating delivered the small boat for shuttling to the dock site. Yvonne

Maris and Jim Pletl helped load the gear prior to sampling. Neville

Reynolds shuttled people and food to/from Seaford, Virginia, while Chris

Krahforst and Eric Stern transported people, gear and the small boat

following completion of sampling.

The following volunteers assisted with sampling for various periods

of time during the 72-hour offshore study: Emily Deaver, Dean Devereaux,

Lore Hantske (entire 72 hours), Rebecca Lovingood, Yvonne Maris (entire

72 hours), Jim Pletl, Eric Stern and Ann Wry. Lore Hantske, Yvonne

Maris and Jim Pletl helped load the gear prior to sampling. Dr. John

McConaugha furnished food through his research grant, while Lore

Hantske, Yvonne Maris, Cathy McConaugha, Jean and Jim Pletl helped

purchase the food. Cathy McConaugha provided transportation for people

and food. Lyle Varnell, with assistance from Les Parker and Jim Pletl,

transported and operated the small boat shuttle. Bill Cooper provided

dock space for the small boat at Rudee Cove Marina, Virginia Beach,

Virginia. Lore Hantske, Yvonne Maris and Eric Stern helped transport

gear following completion of sampling.

The following people volunteered to help with sampling, but weather

cancellations prevented their contributions: Mark Arquette, Bonnie

Brown, Tim Craddock, Tom Deane, Sonya Dunton, Cathy Erickson, Susan

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Farley, Brad Giles, David Hager, Mark Herrenkohl, Julie Herrin, Betsy

Hume, Chris Krahforst, Tom Kovalchuk, Jennifer Loftin, Cathy McConaugha,

Joy Moses, Kathie Mullen, Fred Mutter, Marguerite Nelson, Frank Parker,

Kristi Perino, Steve Reynolds, Andy Strobel, Kathy Varnell, Jay

Woodward, and Kathy Wright.

Consultation and advice were willingly given by Drs. Donald

Johnson, Department of Oceanography, Old Dominion University, Norfolk,

Virginia and Anson H. Hines, Smithsonian Environmental Research Center,

Edgewater, Maryland. Dr. Paul A. Sandifer, South Carolina Wildlife and

Marine Resources Department, Charleston, South Carolina, allowed me to

use his unpublished manuscript and make slides of figures from the same

paper.

I appreciate the advice, consideration and understanding given by

my Sea Grant project coworkers: Sandy Booth, Marie Bundy, Juanita

Grabarczyk, Lore Hantske, Beth Hester, David Johnson, Mario Paulo, Jim

Pletl, Phil Sadler, Lyle Varnell and Harry Winnik.

Expert assistance with figure preparations, slides and other graph

ics was provided by Yvonne Wilson. Richard Kemp, staff photographer,

helped with slides. Both are employed by the Center for Instructional

Development, Old Dominion University, Norfolk, Virginia. I also appre

ciate the time and patience of Lore Hantske, who modeled for some of my

slides.

Special encouragement, assistance and much understanding was given

to me in the final stages of my dissertation preparation by Emily

Deaver, Lore Hantske, Cathy McConaugha, Jean and Jim Pletl, Eric Stem,

and Kathy and Lyle Varnell.

I am grateful for financial support provided for over five years by

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Dr. John McConaugha through his research grant funded by the Office of

Sea Grant, NOAA, Department of Commerce, Grant NA81AA-D-00025.

I feel extremely fortunate having the friendship and encouragement

of Mr. and Mrs. Leonard C. Anderson and Lynn of Norfolk, Virginia.

I am especially indebted to my parents, Ava and Luiell Maris of

Calvert, Texas, for much assistance, encouragement and understanding

throughout my life. Without their concern, this project would not have

been possible.

A few words are not nearly enough to express my extreme gratitude

to my wife, Yvonne. She was always at my side, never complaining, and

always giving me encouragement when things seemed impossible. Yvonne

provided expert assistance in all aspects of my dissertation from field

sampling, to sample washing, and data analysis. She deserves much

credit for typing the entire paper and other aspects of manuscript prep

aration. Her immeasurable love and unselfishness are greatly apprecia

ted.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. DEDICATION

To Dr. A. Geoffrey Fish; Ava, Luiell and Yvonne Maris

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. "...I could never invent any plausible excuse..., nor indeed any one else, which should teach us to regard with complaisance the deviations and eccen tricities which we observe in Nature, and which have all, no doubt, some specific object in view, although difficult or impossible for us to discover..."

John V. Thompson Addenda to Memoir I. On the Metamorphosis of the Crustacea, Zoological Researches No. II. Page 65. 1829.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS

Page

LIST OF TABLES ...... x

LIST OF FIGURES ...... xi

CHAPTER

I. REVIEW OF LITERATURE ...... 1

Vertical Distribution ...... 1

Classical Studies ...... 2

Further Investigations ...... 3

Patterns of Migration ...... 4

Initiating, Controlling and Orienting Factors . . . 6

Biological Significance ...... 6

Vertical Distribution of Specific Organisms .... 7

Dispersal-Recruitment ...... 8

Advantages of Planktonic Larvae ...... 8

Functions of Larvae ...... 9

Factors Causing Fluctuations in Recruitment .... 10

Recruitment Mechanisms ...... 11

Effects of Recruitment Mechanisms ...... 15

Dispersal-Recruitment of Specific Organisms .... 16

Plankton Sampling ...... 17

Techniques ...... 17

Problems...... 17

Importance of the Neuston Layer ...... 19

Clarke-Bumpus Sampler ...... 19

Subsampling Methods ...... 20

Larval Descriptions ...... 21

viii

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. II. FIELD S T U D Y ...... 22

Introduction...... 22

Objectives...... 26

Description of the Study A r e a ...... 28

Materials and Methods ...... 30

Field M e t h o d s ...... 30

Laboratory Methods...... 33

Data A n a l y s i s ...... 36

Results...... 38

Environmental Parameters ...... 38

Collective Larvae and Postlarvae ...... 38

Species and Stage Differentiations ...... 48

Vertical Distribution Groups ...... 53

Dispersal-Recruitment Patterns ...... 64

D i s cussion...... 77

Retained Species ...... 85

Expelled Species ...... 93

Perspectives ...... 96

Future Considerations ...... 97

Summary and Conclusions ...... 99

Literature Cited ...... 103

Appendix A . , ...... 161

Appendix 6 ...... 175

Appendix C ...... 178

Appendix D ...... 202

Appendix E ...... 205

Appendix F ...... 212

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES

Table Page

1. Vertical Distribution-Migration Studies of Decapod L a r v a e ...... 23

2. Mean Volume of Water Filtered per Five Minute Tow at each Station...... 35

3. Environmental Parameters per Station...... 39

4. Species, Stages and Specimens per Station ...... 49

5. Species and Stages, Overlap and Unique among the Stations 49

6. Overall Species and Stage Composition According to Sub/ Infraorder...... 50

7. Overall Percent of Total Catch by Species ...... 51

8. Overall Percent of Total Catch by Stage of Development . 54

9. Stage Groupings Based on Significant Spearman Rank Cor relations at all Depths S a m p l e d ...... 57

10. Dispersal-Recruitment Patterns by Genera ...... 65

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES

Figure Page

1. Map of Study A r e a ...... 31

2. York River Mouth, Collective Larvae and Postlarvae with Depth and Time ...... 41

3. Chesapeake Bay Mouth, Collective Larvae and Postlarvae with Depth and T i m e ...... 42

4. Offshore, Collective Larvae and Postlarvae with Depth and Time ...... 43

5. Percent of Total Catch with Depth, Day-Night, Collec tive Larvae and Postlarvae at each Station ...... 44

6. Weighted Mean Depth of Collective Larvae and Postlarvae with Time per Station...... 46

7. Percent of Total Catch with Depth, Day-Night, Groups . 59

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER I

REVIEW OF LITERATURE

Vertical Distribution

Small-scale distribution and migration patterns are primarily de

termined by the simple, but often overlooked, fact that the oceanic

environment changes far more rapidly in the vertical than horizontal

plane (Longhurst, 1976). Available literature on vertical distribution

and migrational patterns is both extensive and controversial (Murillo

1972). Many explanations of vertical migration, mostly speculative,

have been presented giving the causes, mechanisms involved, and adaptive

significances (Cushing, 1951; Raymont, 1963). Nevertheless, the pheno

menon of vertical distribution is still poorly understood. In addi

tion, various factors possibly interact to initiate changes in vertical

position, and the stimulating agents and intensities may vary with

species, developmental stage, geographic location and time.

Extensive reviews of the literature were prepared by Birge (1897),

Russell (1927b), Kikuchi (1930b), Cushing (1951), Harris (1953), Baylor

and Smith (1957), Bainbridge (1961), Cachon-Enjumet (1961), Raymont

(1963), Banse (1964), Vinogradov (1968), Murillo (1972), Bougis (1976),

Longhurst (1976), Pearre (1979) and Raymont (1983). Extensive experi

mental studies of vertical distribution are included in Appendix A

(Table A-l).

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Classical Studies

The early history of vertical distribution studies was summarized

in lengthy detail by Cushing (1951) and Vinogradov (1968). According to

the latter review, Cuvier, in 1817, was the first to record observations

on diurnal vertical migration. He noted that cladocerans were generally

located at the surface during the morning and evening, but descended in

the warmest part of the day.

Two basic approaches were used by the early investigators of

vertical migration. In the first method, observations taken at the

surface throughout the day and night revealed that many animals were

found at the surface only at night. The second method was employed to

compare vertical distribution at given times during the day and night.

Results showed that animals moved toward the surface at night (Cushing,

1951).

By the end of the 19th century certain things were known about

diurnal vertical migration: a wide variety of organisms were involved,

but some species did not migrate, while others migrated in reverse;

migrations occurred in all oceans and latitudes; and some migrations

exceeded 500 m in distance.

Michael (1911) combined the two methods in observations of chae-

tognaths near San Diego, California over several weeks. He related the

disappearance of animals from depths during the day to appearance near

the surface at night in a time sequence. The extremely precise tech

niques of Michael led to a period of about 40 years in which a vast

amount of information was obtained concerning diurnal vertical migra

tion.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3

Further Investigations

1. Bathyscaph

Nets have not been the only equipment used to investigate vertical

distributional patterns. The bathyscaph was designed and first used by

Beebe (1935), and further submersibles were employed mainly during the

1950’s. A review of studies using the bathyscaph was presented by Gold

and Warsaw (1980).

2. Deep Scattering Layer

The investigation of vertical movements of the plankton using sonic

methods began during World War II. Early studies of the deep scattering

layer include Hersey and Moore (1948), Raitt (1948) and Hersey et al.

(1952), The deep scattering layer has been extensively reviewed by

Tucker (1951), Hersey and Backus (1962), Cushing (1973) and Farquhar

(1977). Farquhar (1971), and Anderson and Zahvranec (1977) compiled

information presented at symposia on sound scattering.

3. Bioluminescence

Bioluminescence of marine organisms provided another method for

studying vertical distribution. Boden and Kampa (1957, 1964), and Nicol

(1958), perfected methods of measuring bioluminescence and using the

information to trace vertical movements in the sea. Recent reviews of

bioluminescence include Morin (1983), and Young (1983).

4. Migrating Parachute Drogue

Miller (1970) used a migrating parachute drogue as a "model animal"

to study horizontal displacement due to vertical migration.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4

Patterns of Migration

1. Diurnal Cycle

According to Cushing (1951) the general pattern of diurnal vertical

migration can be divided into five parts: (1) ascent towards the sur

face from the day depth; (2) midnight movement away from the surface;

(3) dawn rise back to the surface; (4) sharp descent to the day depth

when sunlight penetrates the water; (5) variable day depth. Typically

the ascent is an active swimming process, with rates varying according

to species (Foxon, 1934; Ryland, 1963). Enright (1977a) provided the

most rapid ascent rates for copepods at 30-90 m/hr sustained for periods

exceeding one hour. In contrast, Rudyakov (1970, 1972a,b) reported that

the descent was often a passive sinking process. Passive sinking rates

were provided by Stepanov and Svetlichnii (1976) and largely depend on

surface area and specific gravity.

Below the euphotic zone, diurnal vertical migration likely occurs,

but is unsubstantiated by a confusion of literature at present.

Vinogradov (1955) proposed a "Ladder of Migrations" hypothesis in which

organic material is actively transported downwards by coprophagy and

predation between overlapping patterns of vertical migration to at least

4000-5000 m. The hypothesis remains unproven, but Longhurst (1976)

presented evidence for vertical migration below levels of light

penetration.

2. Longer-Term Migrations

Vertical movements are also known to occur over periods longer than

a single day. Generally, these migrations have been separated into

"seasonal", in which a species varies its vertical position according to

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times of the year, and "ontogenetic", in which different life stages

occur at various depths. Seasonal and ontogenetic migrations are often

the same, due to species with several generations per year or larval

development which extends over seasons (Longhurst, 1976). Longer-term

migrations have been investigated by Langford (1938), Ostvedt (1955),

Sekiguchi (1975a,b, 1976a,b,c), and Rudyakov (1984).

3. Regional Differences

During periods of continuous summer sunlight in polar regions,

diurnal vertical migration may be entirely suppressed (Bogorov 1938,

1941, 1946a,b). In the autumn, typical vertical migrations occur, while

in the total darkness of winter, most species remain at a constant lower

depth. Digby (1960, 1961) observed diurnal migrations under constant

daylight in quieter, more stratified areas of Spitzbergen. Buchanan and

Haney (1980), and Longhurst et al. (1984) also studied the effects of

polar conditions on vertical migration.

4. Anomalies

Reversed vertical migration normally occurs in some species of

copepods, cladocerans and rotifers (Kikuchi, 1930a; Worthington, 1931;

Gardiner, 1933; Worthington and Ricardo, 1936). Dumont (1972) proposed

that competition caused reversed migration by the rotifer, Asplanchna

priodonta (Gosse); while Ohman et al. (1983) reported that the copepod,

Pseudocalanus sp., escaped from predators by using reversed vertical

migration. Unusual occurrences of reversed migration due to extremes in

pH were reported by Bayly (1963) and Connell (1978). During solar

eclipses, certain organisms reacted as if the sun were setting (Backus

et al., 1965; Skud, 1967; Franceschini et al., 1970).

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5. "Uferflucht"

"Uferflucht" or avoidance of the shore due to vertical migration

was proposed by Burkhardt (1910). Davis (1955) provided a description

of the process, and Siebeck (1964) concluded that "Uferflucht" does not

necessarily result from vertical migration.

Initiating, Controlling and Orienting Factors

Light is generally accepted as the most important factor stimula

ting vertical migration. Temperature is an important accessory factor,

while pressure and gravity are auxilliary factors which cannot be ne

glected (Bougis, 1976). Much confusion exists as to how environmental

factors initiate vertical movements, and the possible biological signi

ficances of responding to the stimuli. A basic consideration is that

vertical migration does not affect the entire population, and various

species, stages, and even individuals react differently to the same

stimulus. Sameoto (1984) discussed effects of environmental factors on

vertical distribution. Reviews of orientation to light were presented

by Baylor and Smith (1957), Ringelberg (1964), Blaxter (1970), Segal

(1970) and Forward (1976b). In recent years, the importance of physio

logical rhythms as factors in vertical migration have become apparent.

Harris (1963), and Allen (1966, 1972) reviewed physiological rhythms of

crustaceans. Appendix A (Table A—2) lists various factors proposed for

vertical migration with corresponding studies.

Biological Significance

Longhurst (1976) summarized the more probable hypotheses concerning

biological implications of vertical migrations. The major significances

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include: (1) avoidance of predation (Clarke, 1936; Hardy, 1953; Zaret

and Suffern, 1976; Wright et al., 1980; Iwasa, 1982; Williamson and

Magnien, 1982; Alldredge and King, 1985), (2) horizontal dispersion and

transport (Hardy, 1953; Grindley, 1964; Woodmansee, 1966b; Longhurst,

1968; Miller, 1970; Evans, 1978), and (3) bioenergetic advantages

(McLaren, 1963; Kerfoot, 1970; Arashkevich, 1971; Gatten and Sargent,

1973; Enright, 1977b; Enright and Honegger, 1977; Tseitlin, 1977, 1982;

Klyashtorin, 1984; Petipa and Ostravskaya, 1984; Lamport: and Taylor,

1985).

Vertical Distribution of Specific Organisms

Tables A-3 and A-4 of Appendix A list studies of vertical distribu

tion in non-crustacean and crustacean species, respectively. Bainbridge

(1961) provided an extensive table on vertical migration studies of

crustaceans.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Dispersal-Recruitment

Recruitment requires that sufficient numbers of larvae, postlarvae

or juveniles survive and remain within, be carried to, or return to a

given region to replenish the parental population (Sandifer, 1975).

Larval dispersal and postlarval recruitment are especially important

for ecological and often economic reasons, but very little is known

concerning specific mechanisms. Thorson (1946, 1950, 1961, 1964, 1966)

provided extensive information on reproduction and larval ecology of

marine benthic invertebrates. Carriker (1967) reviewed larval ecology,

reproductive strategies, distribution and movements of estuarine

species, and Goy (1976) summarized previous studies concerning es

tuarine decapod larval distributions and dispersal patterns.

Advantages of Planktonic Larvae

A large majority of marine benthic organisms develop through plank

tonic larvae (about 67% of temperate species, about 90% of tropical

species) (Thorson, 1946). Three types of pelagic larvae are known: (a)

lecithotrophic larvae (about 10%), which do not feed and originate from

large yolky eggs spawned in low numbers; (b) planktotrophic larvae with

a long pelagic life (2-4 weeks) (about 85%), which actively feed and

originate from small eggs spawned in high numbers; (c) planktotrophic

larvae with a short pelagic life (a few hours to a very few days) (about

5%) (Thorson, 1950). Mileikovsky (1971) and Sandifer and Smith (1979)

summarized various advantages of planktonic larvae: (1) greater poten

tial for dispersal; (2) increased gene flow through increased mixing;

(3) potential for quick population recovery after a major disaster; (4)

ability to expand quickly and colonize favorable habitats; (5) lessens

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danger of overcrowding; (6) decreases inter- and intraspecific competi

tion for food; and (7) allows for utilization of high energy phytoplank

ton as a food source.

Functions of Larvae

The main biological fimctions of planktonic larvae include: (1)

extension of species distribution to new areas; and (2) recruitment of

parental populations already established (Mileikovsky, 1972). Both

mechanisms require larval survival in sufficient quantities to compen

sate natural adult mortality, if a stable population is to be main

tained. Planktonic mortality is extremely high but large numbers of

eggs per female are not uncommon. For example, blue crabs (Callinectes

sapidus Rathbun) average 1-2 million eggs per female (Tagatz, 1968).

Munro and Jones (1968) found that the survival rate of the pink

shrimp (Penaeus duorarum Burkenroad) in Florida averages 80.4% per day

during the average 35 day developmental period. Only 0.05% of the orig

inal population survived to enter nursery grounds as postlarvae. Some

6% of the postlarvae survived to adult capture.

Mileikovsky (1971) and Strathmann (1974) noted several strategies

for planktonic survival. Varying the duration of the pelagic period can

be very important. Decreasing planktonic time usually increases surviv

al, while extended time often increases the chance of spreading (but

does not necessarily increase the chance of finding a favorable site).

Prolonged release of larvae is important for species with long-lived

planktonic stages, while repeated release aids organisms with short

development times. Spreading the larvae over a wide vertical distance

helps in protection and enhances horizontal spreading. Scheltema (1966,

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1968, 1971a,b,c, 1975) hypothesized that larvae act as genetic links

between disjunct, geographically isolated populations through dispersal

over long distances by ocean currents.

Factors Causing Fluctuations in Recruitment

Recruitment to benthic populations involves a wide range of fac

tors. Mileikovsky (1968a) believed that adult distribution was the

single most significant factor, while distance from adult populations

also greatly affects recruitment strength (Gnewuch and Croker, 1973).

The expandability of larvae is largely determined by the quantity of egg

production (Hidu, 1978) and corresponding larval types (Thorson, 1950,

1961). Jackson and Strathmann (1981) proposed that larval mortality

from offshore mixing links precompetent and competent periods of devel

opment. Life span of the species indicates how often recruitment is

needed. For example, populations of long-lived barnacles, (Tetraclita

spp.) in California needed successful recruitment only every two years

(Villalobos, 1979). Hidu (1978) mentioned that differential travel in

current systems causes recruitment fluctuations, as does natural mor

tality along with predation (Gophen, 1978; Matthews et al., 1978).

Eventually, the concentration of larvae and postlarvae in particular

areas is necessary for recruitment (Hidu, 1978), and ultimately a stimu

lation to set is needed. Food, light, temperature and substrate are a

few factors influencing settling behavior (Thorson, 1950, 1966).

Thus, settlement density is not a function of planktonic supply of

recruits (Connell, 1960), and recruitment is by no means a routine

process. The major characteristic of recruitment is its striking unpre

dictability (Sutherland and Karlson, 1977).

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 11

Barnes (1956) listed a number of factors causing annual recruitment

fluctuations: (1) lowered viability of larval input (also noted by

Redfield and Vincent, 1979), lowered parental egg production, or adverse

conditions affecting embryonic development; (2) abnormal increase in

larval predation (likewise studied by Hurley, 1975; and Forbes, 1977);

(3) harmful effects of the physical environment including: fluctuations

in rainfall (salinity), temperature extremes, winds from the wrong

direction or lack of winds, and changes in current patterns; (4) adverse

chemicals in the water; (5) defective sampling (net clogging, avoidance,

wrong direction/time, insufficient volume filtered, patches, wrong

equipment); (6) biotic factors of dense phytoplankton blooms; and (7)

absence of an adequate food supply. Barlow (1955) and Mileikovsky

(1968b) presented data that supported the creation and maintenance of

small, sterile "pseudopopulations" by fluctuations in water circulation.

Recruitment Mechanisms

Sandifer (1975) and Scheltema (1975) listed the factors for an

overall consideration of recruitment in a given area: (1) number of

larvae retained — important in maintaining an endemic adult population;

(2) number of larvae flushed out — important in establishing gene-flow,

possibly maintaining and extending the population, and (3) number of

larvae immigrating from some outside region — important in introducing

new genetic variability and maintaining continuity of distant adult

populations. Likewise, the number of larvae expelled with later reinva

sion is important. Johnson (1982) assigned brachyuran postlarvae to

three appropriate recruitment strategies: retained estuarine, expelled

estuarine and retained coastal.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 12

1. Retention

a. Nursery areas

S^mme (1933) noted that copepods hatching early in the flood tide

were generally retained in the Norwegian Sea. Cronin (1979, 1982) found

that short development time, and high survival, together with small

tidal exchanges, leads to almost automatic retention.

b. Tidal currents

Bousfield (1955), Sandifer (1973b), and Penn (1975) studied the

effects of tidal flow on retention. Many larvae migrate vertically into

the water column during the appropriate tidal phase. The flood tide

carries larvae into the estuary, while the ebb tide transports larvae

out to sea.

c. Ontogenetic migrations

Bousfield (1955), Sandifer (1973b), Goy (1976), and Lough (1976)

found that larvae of different stages occur at different depths. Early

stages are often distributed near the surface, while later stages are

found close to the bottom. Most vertically stratified estuaries display

a net surface flow seaward and a net bottom flow landward due to density

differences in the water masses.

d. Cyclic vertical migrations

Short-term vertical migrations to the depth of zero net motion are

common in estuarine larvae (Woodmansee, 1966b; Cronin, 1979). Such

larvae are probably influenced by one or more of the major estuarine

cycles: day/night light cycle, flood/ebb tidal cycle; slack/flow tidal

current cycle.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 13

e. Circulation patterns

Circulation patterns, especially counterclockwise transport

mechanisms, are important in larval retention (Fish, 1936; Redfield,

1941; Ketchum, 1954; Manning and Whaley, 1954; Bousfield, 1955; Trinast,

1975). Rajyalakshmi (1980) stated that monsoon flood waters were a

major larval transport mechanism in India.

f. Behavioral and physiological adaptations

Larval dispersal is either an active process in which horizontal

movement is controlled by vertical migration or a passive process

completely carried out by advective or turbulent processes in the water

column (Makarov, 1969; de Wolf, 1981; Lambert and Epifanio, 1982; Gagnon

and Lacroix, 1983; Hannan, 1984).

(1) passive trapping

de Wolf (1973) found that barnacle larvae were being trapped in a

Dutch estuary due to lack of flushing. Larvae were moved to the head of

the estuary during flood tides, but ebb tides were too weak to prevent

retention.

(2) active processes

Manning and Whaley (1954), Cronin (1979), and Stephenson (1980)

stressed the importance of environmental factors including light, sali

nity, temperature and pressure on larval retention. Internal factors

such as age, nutrition (starved larvae abandon recruitment in search of

food), endogenous rhythms and duration of planktonic life (the shorter

the larval period, the better the chances of retention) are also impor

tant factors. Population genetic factors affecting dispersal were stu

died by Burton and Feldman (1982), Hedgecock (1982), and Strathmann

(1982).

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 14

2. Immigration

a. Currents

Efford (1970) proposed four hypotheses for immigration by the

anomuran mole crab, Emerita analoga (Stimpson), in California: counter-

current, gyral, nursery area, and rearing current hypotheses. The mole

crab is unusual in having a long (four month) developmental period with

8-11 zoeal molts, but relatively few eggs are produced (Johnson, 1939).

Pachygrapsus crassipes Randall, a brachyuran crab, also has a long

developmental period of two to three months in California, with offshore

transport of larvae (J. R. McConaugha, personal communication).

b. Rafting

Knudsen (1960) found that megalopae of xanthid crabs often float on

algae. Wickham (1979) noticed large numbers of megalopae of the dunge-

ness crab, Cancer magister Dana, within gonozooids of the hydroid,

Velella velella (Linnaeus), along the California coast. Rafting by

phyllosoma larvae of spiny lobsters was mentioned by Shojima (1963) and

Thomas (1963).

c. Environmental and behavioral factors

Cronin (1979) noted that crab larvae are influenced by light, sali

nity, temperature and substrate. Ruello (1973) found that young school

prawns, Metapenaeus macleayi (Haswell), in Australia probably utilize

dissolved organic compounds in estuarine water to direct movements back

to an estuary. Hopkins et al. (1981) stated that the landward occurrence

of 69 planktonic and 92 micronektonic species was significantly corre

lated with bottom depth and distance from open water. The importance of

wind in distributing near-surface larvae has been examined by Southern

and Gardiner (1932), Voronina (1958), Langford and Jermolaev (1966),

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Verwey (1966a), George and Edwards (1976), Johnson et al. (1984), and

Johnson (1985b). Shanks (1983, 1985) reported that tidally forced

internal waves might aid in the shoreward transport of pelagic larvae.

Effects of Recruitment Mechanisms

The tendency to exhibit retention or immigraton mechanisms is

influenced mainly by the degree of dependence on estuaries of a given

species. Dittel and Epifanio (1982) found that larvae of crab species

strongly dependent on estuaries tended to congregate near the bottom

where net flow is landwards, thus favoring retention. Species not as

estuary-dependent had larvae commonly at the surface, which suggests

flushing out of the estuary with recruitment by immigration.

Sandifer (1975) hypothesized that natural selection for behavioral

patterns which promote retention may be taking place among euryhaline

marine crustaceans and probably gave rise to the true estuarine species

with planktonic larvae. Retention may also reduce gene flow between

populations. Therefore, a tendency towards isolation and divergent

evolution may increase in populations restricted to estuaries.

Sandifer and Smith (1979) further postulated that the colonization of

freshwater through estuaries is often accompanied by a decrease in the

number of larval stages, a decrease in duration of the larval period,

along with increased larval retention (Sandifer, 1975).

Strathmann (1982) proposed that larval dispersal is an accidental

consequence of planktonic existence. According to Strathmann, varying

favorability does not select for spread of larvae among estuaries, and

areas outside of estuaries are often safer for development. Further

more, when there is selection for larval export from estuaries, it is

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selection for migration to more favorable areas for larval development

and not dispersal.

Dispersal-Recruitment of Specific Organisms

Tables A-5, A-6 of Appendix A list studies of dispersal and recruit

ment in non-crustacean and crustacean species, respectively.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plankton Sampling

Techniques

The history of plankton sampling has been reviewed by Fraser (1968)

and Herman and Platt (1980). Dovel (1964) discussed specific methods

for estuarine sampling. Net towing studies were conducted by Aron et

al. (1965), and Barkley (1964,1972). Methods of plankton collection

using pumps were presented by Gibbons and Fraser (1937), O'Connell and

Leong (1963), and Beers et al. (1967). Studies of replicate sampling

included: Gardiner (1931), Barnes and Bagenal (1951), Barnes and

Marshall (1951), Cassie (1959c), Hopkins (1963), and Angel (1969b).

Jacobs and Grant (1978) provided guidelines for quantitative zooplankton

sampling.

Problems

Kofoid (1897) listed sources of error in the plankton method, while

Winsor and Walford (1936), along with Winsor and Clarke (1940), noted

sampling variations in plankton net catches. Angel (1977) summarized

plankton sampling problems and limitations.

1. Mesh Selection

Heron (1968) reviewed use of plankton gauze and noted that the

specific gauze used in a net influences the size of the organisms

caught, filtration efficiency, drag, clogging, mesh velocity and condi

tion of the catch. Saville (1958) and McGowan and Fraundorf (1966) had

previously studied the effects of mesh selection on catch.

2. Filtration Performance

Tranter and Smith (1968) presented a review of the interaction

between net and water. This collection of disturbances, called the

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 18

filtration performance, is composed of filtration efficiency, filtration

pressure (across meshes) and perhaps mesh velocity. Filtration perfor

mance determines the volume of water filtered by the net and influences

the catch condition and composition. Other studies of filtration per

formance included: Tranter and Heron (1965,1967), Tranter (1967), and

Smith et al. (1968).

3. Avoidance

A review of avoidance of samplers was written by Clutter and Anraku

(1968). Net size, towing velocity and light conditions all affect net

avoidance. Other studies of avoidance were conducted by Fleminger and

Clutter (1965), Singarajah (1969), Tranter et al. (1969), and Laval

(1974).

4. Extrusion

Vannucci (1968) reviewed the problem concerning loss of organisms

through the meshes. The main factors controlling net selectivity

include: escapement, nature and weave of the material, clogging and age

of the net.

5. Patchiness

The uneven spatial and temporal distributions of planktonic organ

isms make sampling especially difficult. The problem of plankton

patchiness was reviewed by Cushing (1962), Steele (1976, 1977) and

Mackas et al. (1985). Reasons for patchy distribution were given by

Brandi and Fernando (1971), while Fasham (1978) provided extensive

statistical and mathematical analyses of patchiness. Cassie

(1959a,b,1963) noted factors influencing variations in microdistribu-

tional patterns of plankton, and Omori and Hamner (1982) discussed

problems, along with an assessment of population behavior, relating to

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 19

patchiness. Other studies of variability in plankton distribution in

cluded: Tonolli and Tonolli (1960), Wiebe and Holland (1968), Wiebe

(1970,1971), Alldredge and Hamner (1980), Gagnon and Lacroix (1981), and

Alcaraz (1983).

Importance of the Neuston Layer

Until recently the extreme upper water layer in contact with the

atmosphere was largely ignored in plankton sampling programs. Johnson

(1982) and Provenzano et al. (1983a) discussed the significance of the

neuston layer in larval and postlarval dispersal of decapod crustaceans.

Up to 99% of blue crab larvae and postlarvae (C_. sapidus) were collected

from the neuston layer in the two previously mentioned studies. Organ

isms in the neuston tend to be greatly influenced by wind-driven circu

lation (Johnson, 1985b). Neuston distributions of plankton were pre

sented by Champalbert (1971a,b), Hempel and Weikert (1972), Hardy

(1982), and Holdway and Maddock (1983a,b). Various floating and skim

ming samplers for the neuston were devised by David (1965), Harvey

(1966), and Schram et al. (1981).

Clarke-Bumpus Sampler

Clarke and Bumpus (1939,1940,1950) developed an efficient and

effective opening-closing plankton sampler. Various modifications were

presented by Comita and Comita (1957), Paquette and Frolander (1957),

Paquette et al. (1961), while Yentsch and Duxbury (1956), McHardy

(1961), and Regan (1963) provided calibration factors. Regan (1963)

discussed the effects of net mesh variations, and Tranter and Heron

(1965) studied filtration characteristics of the Clarke-Bumpus plankton

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 20

sampler. A detailed comparison with a plankton pump was given by Wiborg

(1948).

Subsampling Methods

Wiborg (1962) reviewed various methods of dividing plankton collec

tions, while Venrick (1971) discussed the statistics of subsampling, and

Horwood and Driver (1976) presented theoretical techniques. Methods of

plankton subsampling include: plankton splitter (Gibbons, 1933), whirl

ing vessel (Wiborg, 1951), modified whirling vessel (Kott, 1953), Folsom

splitter (McEwen et al., 1954), splitting chamber (Motoda, 1959), a

"new" subsampling device (Burrell et al., 1974), pipette with bubbling

(McCallum, 1979), and sieve fractionation (Alden et al., 1982). The

Folsom splitter has been the most reliable and widely used method.

McEwen et al. (1954) conducted a statistical analysis, while Longhurst

and Siebert (1967) provided techniques for skill in using the Folsom

plankton splitter. Subsampling procedures were provided by Jacobs and

Grant (1978), while Haasman (1983) constructed a new sorting device.

Statistical treatments of subsampling and discussions of clumping prob

lems were provided by Dahiya (1980), Sell and Evans (1982), Van Guelpen

et al. (1982), George et al. (1984), and Griffiths et al. (1984).

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Larval Descriptions

Central to any biological investigation is the accurate identifica

tions of the organisms studied (Sandifer, 1972). Likewise large varia

tions in distribution and environmental tolerances have been found among

larvae of different species of the same genus, and even different devel

opmental stages of the same species (Dudley and Judy, 1971; Sandifer,

1972, 1973b, 1975; Goy, 1976; Dittel and Epifanio, 1982; Maris and

McConaugha, 1983; McConaugha et al., 1983). Thus, studies in which

species and stages were not separated are only of minimal value.

Gurney (1939) provided an extensive bibliography on decapod larvae

and a review of larval biology (Gurney, 1942). Although various indi

vidual larval descriptions have been subsequently provided, much more is

still needed. In an area as well studied as the Chesapeake Bay, less

than half of the nearly 100 species of decapods have larval descriptions

(Goy, 1976). In addition, only 44% of 228 known species from the Middle

Atlantic Bight have even partial descriptions (Maris, unpublished).

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CHAPTER II.

FIELD STUDY

Introduction

Larval dispersal and postlarval recruitment are extremely signifi

cant processes in the life histories of ecologically and economically

important species of decapod crustaceans. Vertical positioning of

larvae and postlarvae in the water column plays a major role in the

particular strategies of retention or immigration that are employed.

Large-scale variations in distribution occur not only at the species

level but also among different stages of the same species (Dudley and

Judy, 1971; Sandifer, 1972, 1973b, 1975; Goy, 1976; Dittel and Epifanio,

1982; McConaugha et al., 1983). See Table 1 for more specific informa

tion concerning studies on vertical distribution of decapod larvae.

Studies of vertical distribution and diurnal migration are espe

cially lacking for decapod larvae and postlarvae with only 14 known

studies, in addition to the present one (see Table 1). In 50% of the

previous studies sampling was not extended past a 24-hour period, there

fore very little can be noted statistically concerning possible verti

cal migration. The only extensive study using decapod larvae was con

ducted by Cronin (1979) with the low salinity estuarine crab

Rhithropanopeus harrisii (Gould) which cannot be considered characteris

tic of all decapod larvae.

Of the previous studies, 57% examined only one species, 43% did not

differentiate among stages of development, and 71% did not sample from

surface to bottom. Studies of only one species are of minimal value in

making generalizations about decapod larvae and postlarvae collectively.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

--- harrisii crangon longipes cygnus americanus Callianassa sp. Brachyura sp. Caridea sp. Rhithropanopeus to genera to only identifications Panulirus 1 1 Uca spp. 5 5 5 Crangon 4 4 Homarus 16 16 26 No. Stages Comments

Sampled Species Depths No. (4 depths) (4 (3 depths) (3 (5 depths) (5 depths) (8 depths) (8 depths) (4 cm 10 6 3 1 m 1 - epibenthic 11 100-240 m 100-240 neuston-epibenthic 1 decapod decapod larvae. surface surface-bottom 1 1 0.5-45 cm 1 0-40 m 0-180 m 12 1

Sampling 1 hr 1 2 hr 2 2 hr 2 2 hr hr 2 hr 2 4 4 hr (daylight,dusk, about hr 4 midnight,dawn) 8 tidal phases

(2 stations) (2 hr14 stations) (4 hr 2 (6 stations) (6 14 hr 14 24 hr 24 hr 57 56-100 hr each 24 each hr 24 8 days

1927a,1928,1931b) Study Study Duration Interval Scarratt (1973) Chittleborough and Thomas (1969) each hr 24 (2 stations) Russell (1925, Russell (1925, hr 17-18 Cronin (1979) Howard (1978) Table 1. Table 1. Vertical distribution-migration studies of DeCoursey (1976) Goy (1976) Robertson and Makarov (1976)

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. >* h O 4

------cygnus sapidus pump pump sampling zoeae,megalopae pump pump sampling penaeid larvae Panulirus Rhithropanopeus 1 Callinectes 8 9 — laboratory No. 160 Stages Comments 1 1 1 7 No. 15 64 41 — Species

Sampled Depths (4 depths) (4 (5 depths) (5 (lucite (lucite column) (5 depths) (5 (5 depths) (5 bottom surface-20 m epibenthic night m 0-90 0-19 m 1 hr 1 2 hr2 0-300 day m 3 3 hr neuston-epibenthic 3 3 hr neuston- 4 4 hr Interval Sampling

2 2 times (2 stations) (2 (2 stations) (2 24 hr24 3 hr 5, m 11, 20 24 24 hr 28, 28, 46 hr 70 70 hr hr 2 surface and each hr 30 each sampled 8 8 days each 72 each hr 72 Duration •

(1983b) (1982) Study Cronin and Forward (1979) Epifanio (1982) Provenzano (1979) Provenzano et al. Rimmer and Phillips (1979) Rothlisberg Table 1. Table 1. continued Epifanio (1985) Dittel and Brookins and Present study stations) (3

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 25

However, results of various individual species studies could be compiled

for better overall understanding. Likewise, little information on

vertical distribution can be gained from studies in which sampling was

not conducted from neuston to epibenthic layers and/or samples were not

taken at night. Also, many previous conclusions concerning both horizon

tal and vertical distribution patterns must be viewed with certain

skepticism due to extremely low numbers of individuals collected.

The present study was longer than 79% of the known previous stu

dies, therefore statements can be made about possible vertical migra

tion. Only three previous studies were longer than 72 hours and each

examined only one species. Twenty-six more species (273%) and 96 more

stages (250%) were differentiated than in any previous study, with

possibly a better understanding of overall vertical distributional pat

terns and influences on dispersal-recruitment mechanisms.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Objectives

The present study was undertaken to investigate variations in ver

tical distribution of prejuvenile decapod crustaceans according to tem

poral (diurnal), spatial (estuarine, transition, oceanic), ontogenetic

(larval stages, postlarvae) and environmental factors (light, tempera

ture, salinity, wind speed, wind direction, sea state, cloud cover and

tidal cycles). A further objective was to study how variations in ver

tical positioning might affect larval dispersal and eventual postlarval

recruitment mechanisms (retention, expulsion with reinvasion).

The specific objectives were to test the following null hypotheses

concerning diurnal vertical distribution of decapod larvae and postlar

vae :

Ho (1) = no differences occur in relation to distana

estuary.

Ho (2) = no differences occur due to depth.

Ho (3) = no differences occur due to light cycles.

Ho (4) = no differences occur due to tidal cycles.

Ho (5) = no differences occur due to temperature.

Ho (6) = no differences occur due to salinity.

Ho (7) = no differences occur due to wind direction.

Ho (8) = no differences occur due to wind speed.

Ho (9) = no differences occur due to cloud cover.

Ho (10) = no differences occur due to sea state.

Ho (11) = similar stages show no differences among different

species.

Ho (12) = no differences occur among developmental stages of a

given species.

with permission of the copyright owner. Further reproduction prohibited without permission. 27

Ho (13) = diurnal vertical migration does not occur.

Any null hypothesis which could not be accepted was thoroughly investi

gated with the purpose of examining any possible effects of diurnal ver

tical distribution of decapod larvae and postlarvae on dispersal-

recruitment mechanisms.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Description of the Study Area

The Chesapeake Bay ana its tributaries represents the largest

estuary in the United States, measuring 289 km in length, 48 km at its

widest point, and 29 km at the mouth between Cape Charles and Cape

Henry. Surface area is 11.5 billion square meters with a volume of 74

billion cubic meters of water. Mean depth is about 8 m and normally the

tidal range is about 1 m (Hargis, 1981).

Formation of the Chesapeake Bay, as a coastal plain estuary,

occurred by drowning of the Pleistocene-incised Susquehanna River valley

(Ludwick, 1971). Large expanses of four states (New York, Pennsylvania,

Maryland, Virginia) and lesser portions of two others (West Virginia,

Delaware) are drained by the Chesapeake Bay. The Susquehanna River

system provides about 51% of freshwater input to the system. The rest

is provided by the Potomac (18%), James (14%), Rappahannock (4%), York

(2%), and 11% from rivers on the eastern shore (Hargis, 1981).

A two-layered net flow is usually established in the bay mouth re

gion with a new outflow of lower salinity estuarine water at the sur

face. Net inflowing oceanic water of higher salinity generally, enters

along the bottom (Boicourt, 1981). Typically semidiurnal tides occur

throughout the year (Hargis, 1981).

Coastal areas are influenced by a surface plume leaving the bay

mouth and veering southward due to the Coriolis effect. Bottom currents

usually flow toward the south except for net inflow near the bay mouth

(Bumpus, 1973; Boicourt, 1981). Nearshore currents are often weak and

poorly-defined with wind-driven circulation dominating flow patterns

(Johnson et al., 1984; Johnson, 1985b). Also, strong, persistent winds

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 29

can initiate inflow or outflow surges in the bay (Wang and Elliott,

1978a,b; Wang, 1979a,b).

Other studies of circulation patterns within the Chesapeake Bay

include: Pritchard (1952b), Heltzel (1973), Johnson (1976b), and

Wilson and Okubo (1978). Circulation of the Mid-Atlantic Bight was

studied by Bumpus (1965,1969,1973), Harrison et al. (1967), Beardsley et

al. (1976), Boicourt and Hacker (1976), and Cox and Wiebe (1979).

Johnson (1976a) provided a bibliography of shelf circulation studies

along the Mid-Atlantic Bight. Current patterns in the shelf region

adjacent to the Chesapeake Bay were investigated by Joseph et al. (1960)

and Norcross et al. (1962). Chase (1959) studied the effects of wind on

currents off the eastern United States.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Materials and Methods

Field Methods

Three stations were established for the present study:

(1) 37°12'N, 76°16'W - York River Channel, Buoy R-18, York

River Mouth, Chesapeake Bay (30 August - 2 September 1984),

(2) 36°58'N, 76°07'N - Thimble Shoal Channel, Chesapeake Bay

Mouth (29 August - 1 September 1983),

(3) 35°54*N, 75°43*W - Chesapeake Light Tower, offshore (13-16

August 1985) (see Fig. 1).

Mean depths (m) for the stations were as follows: (1) 11.6, (2) 10.7,

(3) 12.8. The stations were chosen to represent estuarine, transition

and continental shelf environments, respectively. Lunar phases and mean

sunrise/sunset during sampling were as follows: last quarter, 31 August

1983, 0636/1937; first quarter, 2 September 1984, 0637/1935; new moon,

16 August 1985, 0622/1957. All sampling was conducted aboard the 19.8 m

R/V Linwood Holton of the Department of Oceanography, Old Dominion

University, Norfolk, Virginia. Station locations were determined by

adjusted Loran-C coordinates.

Each station was occupied for a continuous 72 hr period over six

tidal cycles, from 1200 hours on day one until 1200 hours on day four.

Quantitative plankton samples were collected every three hours from the

following depths: neuston (0.10-0.15 m), 1 m, 3 m , 6 m , epibenthic

(10.7-12.8 m). A total of 375 samples were collected (125 from each

station).

The neuston was sampled with a net modified from one designed by

John Clark, David Johnson and Kathy Philips, Department of Oceanography,

Old Dominion University. The neuston net consists of a rectangular

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 1. Map of study area.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. CO 76°00 CHESAPEAKE CHESAPEAKE BAY RIVER . . YORK

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 32

fiberglass net mouth (31 x 124 cm), buoyed with twin foam-filled PVC

plastic pontoons. A one meter diameter plankton net (#6, 0.243 mm nylon

mesh) was attached to the net mouth and a laboratory flume-calibrated

flowmeter (General Oceanics Inc. Model 2030) was secured to the lower,

outside surface of the net mouth (to insure consistent contact with the

water) (Nishizawa and Anraku, 1956). The neuston net was towed for a

five minute period in a circular path to reduce the surface speed to

about 0.5 m/sec which helped ensure uniform sampling.

All depths below the neuston were sampled with two standard Clarke-

Bumpus plankton samplers (30.5 cm dia. mouth opening), using messenger

controlled opening-closing devices for discrete depth sampling. The

Clarke-Bumpus samplers had internally located flowmeters (identical to

the one described for the neuston net) and were equipped with removable

plankton nets (#6, 0.243 mm nylon mesh). Each Clarke-Bumpus plankton

sampler was towed in a straight line for five minutes at about 1.75

m/sec. The actual depth of each Clarke-Bumpus sampler was calculated

using the formula:

Depth = (meters of wire let out)[cos(wire angle)]. (1)

A calibrated meter wheel measured the wire out, while an inclinometer

was used to determine the wire angle (Moore, 1941). A 60 kg bronze wire

depressor was used to maintain the Clarke-Bumpus sampler at a constant

depth for 6 m and epibenthic tows. An 11 kg lead weight was used for 1

and 3 m tows.

All 1 m and 6 m samples were taken simultaneously using the aft

winch, while 3 m and epibenthic samples were obtained at the same time

using the forward winch. The neuston was always sampled individually

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 33

using the forward winch. Theoretical sampling efficiencies were >90%

for each net (J. R. McConaugha, personal communication).

At the conclusion of each sampling period, a vertical temperature-

salinity-conductivity profile was recorded from surface to bottom (1 m

increments) using a Beckman RS 5 inductive salinometer. Wind speed and

direction were determined with a shipboard anemometer and wind direc

tion gauge, while sea state and cloud cover were estimated by qualified

crew members.

Immediately after collection, each plankton sample was washed

(using a hose with nozzle, attached to a seawater pump) into the PVC

plastic collection bucket (0.946 1, 87 mm dia.) attached to the net. The

sample was then transferred to a glass collecting jar (0.946 1, 87 mm

dia.) containing about 50 ml of concentrated (37% by weight) formalin

buffered by saturation with borax (hydrated sodium borate) (Jacobs and

Grant, 1978). The jar was then filled with filtered seawater to make a

4-5% formalin preservative. In the laboratory, each sample was washed

with tapwater in a 0.125 mm sieve to remove the formalin, and then

reconcentrated in 50% ethylene glycol for storage (Williamson and

Russell, 1965).

Laboratory Methods

Most samples contained large numbers of larval and postlarval

decapods, therefore a Folsom plankton splitter was used to divide the

collection to a manageable level. Samples with few specimens were

sorted in their entirety. Counts of individuals were converted to

densities (total number per cubic meter of water volume filtered through

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 34

the net). The volume filtered for each sample was calculated using the

formula:

V = RK (2)

where V = volume in cubic meters, R = the number of flowmeter

revolutions, and K = the net constant [(distance towed in meters/flow-

meter revolutions)(filtering area of sampler in square meters)]. Table

2 contains mean volume of water filtered calculations per depth for each

station.

All stages comprising about 0.03% or more of the total catch were

collected in sufficient quantities for statistical analysis. Published

descriptions of larvae and postlarvae (see Appendix B) were used for

identifications. At present, local species of Penaeus [P. aztecus Ives,

P. duorarum, P. setiferus (Linnaeus)], Palaemonetes [P. intermedius

Holthuis, P. paludosus (Gibbes), P. pugio Holthuis, P. vulgaris (Say)],

Libinia [L. dubia H. Milne-Edwards, L. emarginata Leach (larvae only)],

Callinectes [C. sapidus, C. similis Williams!. Portunus [P. anceps

(Saussure), P. gibbesii (Stimpson), P. sayi (Gibbes), P. spinicarpus

(Stimpson), P. spinimanus Latreille], Pinnixa [P. chaetopterana

Stimpson, P. cylindrica (Say), P. sayana Stimpson (postlarvae only)],

Uca [U. minax (Le Conte), TJ. pugilator (Bose), U. pugnax (Smith)] cannot

be readily differentiated in field collected specimens. In addition,

Arenaeus cribrarius (Lamarck) cannot be separated practically from

Callinectes sapidus, but more than 95% of previously collected portunid

postlarvae were positively identified as C. sapidus (Johnson, 1982).

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 35

Table 2. Mean volume of water filtered (cubic meters) per five minute tow at each station; standard deviation in parentheses.

Depth (m)

0 1 3 6 11/13

York River 129.021 30.898 30.870 31.059 31.063 Mouth (13.857) (5.067) (5.203) (12.702) (10.234)

Chesapeake 129.026 30.444 30.230 31.513 31.529 Bay Mouth (25.952) (12.956) (13.620) (10.234) (14.571)

Offshore 128.709 29.899 31.113 30.953 31.184 (19.898) (8.459) (8.451) (5.545) (9.203)

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 36

Data Analysis

Descriptive statistics were used initially to assess variations in

distribution with depth. Specifically, the arithmetic mean (X) and

standard deviation (s) were used and calculated according to Zar (1974).

Weighted mean depth (D, in meters) was calculated using the

formula: D = £ nidi (3) N

where, n^ = density of sample i in number per cubic meter, d^ = depth of

sample i in meters, N = total density at all depths in a sampling

period in number per cubic meter. Worthington (1931) first used

weighted mean depth determinations in vertical distribution studies of

plankton. Further refinements in the techniques used were presented by

Gardiner (1933), Pearre (1973) and Roe et al. (1984a). Plots of day-

night percent distribution with depth were made using modifications of

methods used by Pennak (1943) and Shulenberger (1978).

The data were tested for normality by calculating skewness and kur-

tosis values. Results indicated that the data were not normally distri

buted, and transformations (log, arcsine, square root) did not suffi

ciently correct the violations of normality in all instances. There

fore, non-parametric methods of statistical analysis (Zar, 1974) were

generally used for consistency, except in cases where normality was not

critical.

The Mann-Whitney test (statistic U) or non-parametric equivalent of

the two-sample t-test, was used to compare day-night mean depths.

Spearman rank correlation (coefficient rs)was used to make comparisons

among developmental stages, and stages with environmental parameters.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 37

Kruskal-Wallis single factor analysis of variance by ranks (statistic H)

was used to test for depth and tidal variations among stages. A mul

tiple comparison (range) test was not possible due to unequal sample

sizes.

The cross-correlation function (Chatfield, 1980) was used to exam

ine relationships between the time series of light and mean depth of

stages. In the analysis, an auto-correlation coefficient (r^ ) was

calculated for each variable, along with a cross-correlation coefficient

[CXy(k)]. All coefficients were indications of the randomness (lack of

cyclical behavior) of the data sets (sampled at the same interval) and

the degree of correlation between them. Lag ranged from 0 to N/5 in

this determination, where each lag corresponded to three hours. A peak

in cross-correlation coefficients at lag d may have indicated that one

time series was related to the other when delayed by time d. If a time

series was completely random, 95% of revalues were expected to lie

between Values of r ^ which f e^l outside of these limits were

significantly different from zero at the 0.05 level. The size of r^ ,

along with a physical interpretation of the lag were necessary in eval

uating randomness of distribution.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Results

Environmental Parameters

Table 3 contains measurements of environmental parameters for each

station. Mean temperature change with depth (neuston to epibenthic) was

-0.30, -2.01 and -4.52°C for the York River mouth, Chesapeake Bay mouth

and offshore stations, respectively. The York River mouth location had

the highest mean temperature for each depth. Significant inverse Spear

man rank correlation coefficients were obtained between temperature and

light at 0 m (rs = -0.442, p < 0.05) and 1 m (rs = -0.423, p < 0.05) at

the bay mouth station. Coefficients at all other depths and locations

were not significant (p > 0.50).

Mean salinity change with depth (neuston to epibenthic) was +1.48,

+5.03 and +2.27 o/oo (York, bay, ocean). Salinity at all depths in

creased from the York River mouth to bay mouth to offshore.

Mean sea state ranged from 0.24 to 0.45 m, and mean wind speed

ranged from 54.00 to 72.59 m/s. A highly significant Spearman rank

correlation coefficient was obtained between sea state and wind speed at

the neuston depth (rs = +0.786, p < 0.001). Coefficients at all other

depths were not significant. The majority of wind direction readings

were SW for York River mouth and offshore stations and NW for the bay

mouth location.

Collective Larvae and Postlarvae

Differentiation to the species and developmental stage levels are

extremely important due to large behavioral variations. However, general

distributional trends can be studied before species and stages are

examined individually.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table 3. Environmental parameters per station; standard deviation in parentheses.

Temperature (°C)

Depth (m) Station 0 1 3 6 11/13

York River 27.65 27.63 27.58 27.42 27.35 (0.57) (0.56) (0.56) (0.45) (0.44)

Bay mouth 26.21 25.95 25.53 24.71 24.20 (0.77) (0.80) (0.72) (0.46) (0.50)

Offshore 26.60 26.53 26.19 25.59 22.08 (0.77) (0.72) (0.57) (0.65) (l.H)

Salinity (o/oo)

York River 18.75 18.81 19.07 19.62 20.24 (0.61) (0.56) (0.46) (0.48) (0.25)

Bay mouth 23.71 24.17 25.19 27.63 28.74 (1.12) (1.12) (1.22) (1.03) (1.05)

Offshore 30.45 30.68 31.18 32.34 32.72 (1.28) (1.33) (1.34) (1.03) (0.94)

Cloud Sea Wind Station Cover (%) State (m) Speed (m/s) Wind Dir

York River 30 0.26 54.00 28% SW 16% S (20) (0.11) (25.84) 24% NW 4% N] 24% N 4% W

Bay mouth 50 0.24 61.86 36% NW 8% N1 (40) (0.18) (19.81) 32% SE 8% N 12% E 4% S

Offshore 0 0.45 72.59 48% SW (0) (0.17) (18.98) 44% SE 8% S

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 40

The first hypothesis to test was

Ho(l) : no distributional differences occur in relation to

distance from the estuary.

Figures 2-4 show distribution with depth and time at the York River

Mouth (York), estuarine; Chesapeake Bay Mouth (bay), transitional; and

Chesapeake Light Tower (ocean), offshore stations, respectively. Spear

man rank correlation was used to test Ho(l) by comparing distribution

with depth and time among the three stations (see Appendix C, Table C-

1). A significant correlation coefficient at each depth was necessary

to accept the hypothesis for any station combination. Significant

correlations were not found at all depths for any combination. Thus,

Ho(l) was rejected for all situations.

The next hypotheses for testing were

Ho(2): no overall differences occur in distribution due to

depth,

Ho(3a): no overall differences occur in day-night depth dis

tribution.

Ho(3b): no overall differences occur in day-night density

distribution.

Appendix C (Table C-2) contains Kruskal-Wallis test results for collec

tive larval and postlarval distribution with depth. Ho(2) was rejected

at each station due to the significant coefficients, p < 0.001.

Figure 5 gives day-night percent of total catch with depth at each

station. Day-night maxima were as follows: York, 33% - 1 m day, 60% -

0 m night; bay, 52% - 11 m day, 57% - 0 m night; ocean, 39% - 0 m day,

56% - 1 m night. Mann-Whitney test results for collective larvae and

postlarvae with depth, along with mean densities at each station can be

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 2. York River mouth, collective larvae and postlarvae with depth and time.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 41

NIGHT NIGHT NIGHT w m m m

L'»•♦5

m & m ■•,.■“>.;, *.r; * V.;sv> C*^**v>V Va • ». *T o r LU I— lli

o ;Av;—;/ CD oz > IT lli c l (Z Lli CQ

•>» ^v* > lV ?.• ,\ / •• • ir * ,v ;'' BSPS _ 6 m :v“1 *£*! ?: .yi^V -•?>>’ •*i- S S i l l 100 •dT* ** £“■ v yV'i.'.l -SSfs &&

/■ 'Mi?.: *hs i

_ 1 1 m 100 - I k ® ® *

_____ Lj^bSshL%i^_ I i SB

TIME

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 3. Chesapeake Bay mouth, collective larvae and postlarvae with depth and time.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced

NUMBER PER CUBIC METER 1200

1800 i H

NIGHT 0000

06001200

1800 TIME S S 8

NIGHT 0000

0600

1200

1800

NIGHT 0000

0600

1200 42 Figure 4. Offshore, collective larvae and postlarvae with depth and time.

NUMBER PER CUBIC METER 1200 . 1 “ 5 m i 4 ' - - •

» « » » m 6 , m c 1800 & C & 8 S^fcjSPR* 8 W :u>: r~. i >-*;v v .-.* v» * v ; * - \> • ratisME&a ii p §

- • m m w 7 NIGHT 0000 '- 0 2 203

_ 0600 •■ j r--.

1200 1535

» ; pup u p I 1800

5484 i i^&fesss nawifts TIME m m m VS.Wf;*'*". . • V u k ' S f c i ' - ? . ' : «r* i.*n.- - - ;-r2QKs; ;wj

0000 IH NIGHT NIGHT

2858

0600 I'lK

1200

1800 5908 4f^t > 24^fe^#tS i6j|$ils5s s m m i **-V > • * .v^.'*//'. . :S3»#W ^ s r a t f S r S t i * • *"• - ‘ •* •

/V | »/.V \j

1677 1 f t k : . , : ' * I ' i :

0600

2141

1200 43- Figure 5. Percent of total catch with depth, day-night, collective larvae and postlarvae at each station.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. - p • ■c- DAY %DAY NIGHT % COLLECTIVE LARVAE-POSTLARVAE B. B. CHESAPEAKE BAY MOUTH o ) DAY %DAY NIGHT % 8 6 . 1 ( COLLECTIVE LARVAE-POSTLARVAE N.S. (4.24) C. C. OFFSHORE E x Q. a Ui DAY DAY % % NIGHT COLLECTIVE COLLECTIVE LARVAE-POSTLARVAE A. YORK RIVER MOUTH YORK A. E X i— Q. I l l n

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 45

found in Appendix C (Table C-3). Figure 6 gives weighted mean depth

calculations of collective larvae and postlarvae with time at each

station. Day-night weighted mean depths (standard deviation) and sig

nificance level (Mann-Whitney table value = 115) were as follows: York,

5.96 (2.22)-4.24 (2.74) (109, p = 0.10); bay 7.49 (1.62)-3.19 (1.80)

(148.5, p < 0.001); ocean, 1.86 (0.96)-1.41 (0.60) (101, p > 0.20).

Ho(3a) was accepted for 1, 6, 11 m depths and rejected for 0 and 3

m depths at the York River station. Ho(3a) was accepted for 3 and 11 m

depths and rejected for 0, 1 and 6 m depths at the bay mouth station.

Ho(3a) was accepted for 1, 3 and 6 m depths and rejected for 0 and 13 m

depths offshore. Ho(3b) was investigated using the Mann-Whitney test

(Appendix C, Table C-4). Only the York River station exhibited a sig

nificant difference in day-night densities [reject Ho(3b), U = 117, p <

0.005]. Thus, Ho(3b) was accepted for the bay and offshore stations.

Distribution according to environmental parameters was investigated

by testing the following hypotheses [in additon to Ho(3)]:

Ho(4a): no overall differences occur in mean depth due to

tidal cycles.

Ho(4b): no overall differences occur in mean densities due to

tidal cycles.

Ho(5): no overall differences occur in distribution due to

temperature.

Ho(6): no overall differences occur in distribution due to

salinity.

Ho(7): no overall differences occur in distribution due to

wind direction.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 6. Weighted mean depth of collective larvae and postlarvae with time per station.

WEIGHTED MEAN DEPTH (m) 0900 yi ______

1200 ■

1500 ______IE (HR) TIME

OFFSHORE HSPAE A MOUTH BAY CHESAPEAKE OK IE MOUTH RIVER YORK 1800 ,

2100 S£PPIf

0000 NIGHT

0300

0600 46 47

Ho(8): no overall differences occur in distribution due to

wind speed.

Ho(9): no overall differences occur in distribution due to

cloud cover.

Ho(10): no overall differences occur in distribution due to

sea state.

Ho(4a) was tested using the Kruskal-Wallis test in comparisons of depth

distribution according to weighted mean depth variations with light and

tidal phases (see Appendix C, Table C-2). Ho(4a) was accepted for the

overall tidal cycle and day-night phases at both York and bay stations.

However, tendencies toward heterogeneous depth distribution at certain

tidal phases were noted. Ho(4b) was tested using the Kruskal-Wallis

test (Appendix C, Table C-4). The null hypothesis was accepted at all

stations. Offshore tides were not measurable (D. R. Johnson, personal

communication).

Hypotheses Ho(3) and Ho(5)-Ho(10) were examined using Spearman rank

correlations (Appendix C, Table C-5). Significant positive correlations

with light (night) were found at 0 m (York); 0, 1 m (bay); 0, 13 m

(ocean); with temperature at 13 m (ocean); with salinity 1, 3 m (ocean);

with wind direction at 6 m (ocean). Inverse correlations were noted

between temperature and distribution at 0, 1, 3 m (bay), 13 m (ocean);

with salinity at 13 m (ocean); with cloud cover at 11 m (bay). Ho(5)~

Ho(10) were accepted for all depths at the York River station. Ho(6)-

Ho(8) and Ho(10) were accepted at all bay mouth depths. Ho(8)-Ho(10)

were accepted at all offshore depths.

Hypotheses Ho(ll)-Ho(12) concern species and stage difference and

thus cannot be tested for collective larvae. The possibility of diurnal

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 48

vertical migration was studied using time series analysis, specifically

auto-correlation and cross-correlation with the light cycle in testing

the hypothesis:

Ho(13): diurnal vertical migration does not occur for collec

tive larvae,

Ho(13) was accepted at the York River and offshore stations but rejected

at the bay mouth location (see Appendix C, Figure C-l).

Species and Stage Differentiations

A total of 41 species, 160 developmental stages and an estimated

6,000,000 specimens were collected in the present study (see Table 4).

The offshore location provided 86% of the total catch. Species and

stage overlap (Table 5) decreased from estuarine to offshore stations,

York River mouth - bay mouth species and stages overlap was 63 and 53%,

respectively. Species unique to a station ranged from 7-12% and 9-16%

for stages, with percent uniqueness, generally increasing from estuarine

to offshore stations.

Overall species and stage composition according to sub/infraorder

can be found in Table 6. True crabs (Brachyura) accounted for 53% of

the species, 50% of the stages and 92.42% of the total catch. Ano-

murans, thalassinideans and shrimps (Dendrobranchiata, Caridea) made up

^ 2.16, 1.24 and 0.18% of the total catch, respectively.

A breakdown of percent of total catch by the 41 species is listed

in Table 7. Callinectes sapidus constituted 87.40% of the total col

lection followed by Uca spp. (3.45%), Pinnixa chaetopterana Stimpson

(1.74%), Hexapanopeus angustifrons (Benedict and Rathbun) (1.42%),

Pagurus annulipes (Stimpson) (1.32%), and Upogebia affinis (Say)

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 49

Table 4. Species, stages and specimens per station.

Estimated Station No. Specimens (%) No. Species No. Stages

York River 400,000 (7) 29 101

Bay Mouth 400,000 (7) 33 117

Offshore 5,200,000 (86) 24 70

TOTAL 6,000,000 (100) 41* 160*

...... ^ . *no. different (considering overlap)

Table 5. Species and stages, overlap and unique among the stations.

Stations No. Species (%) No. Stages (%)

A. OVERLAP

York River - Bay Mouth 26 (63) 85 (53)

Bay Mouth -- Offshore 19 (46) 43 (27)

Offshore - York River 15 (37) 28 (18)

B. UNIQUE

York River 3 (7) 16 (10)

Bay Mouth 3 (7) 15 (9)

Offshore 5 (12) 26 (16)

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table 6. Overall species and stage composition according to sub/infraorder.

Sub/Infraorder No. Species (%) No. Stages (%) % of Total

Dendrobranchiata 3 (7) 12 (8) 0.03

Caridea 6 (15) 26 (16) 0.15

Thalassinidea 4 (10) 16 (10) 1.24

Anomura 6 (15) 26 (16) 2.16

Brachyura 22 (53) 80 (50) 96.42

TOTAL 41 (100) 160 (100) 100

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table 7. Overall percent of total catch by species.

Species % of total

1. Callinectes sapidus 87.40

2. Uca spp. 3.45

3. Pinnixa chaetonterana 1.74

4. Hexapanopeus aneustifrons 1.42

5. Pagurus annulipes 1.32

6. Upogebia affinis 1.08

7. Pinnotheres ostreum 0.84

8. Neopanope savi 0.51

9. Pinnixa sayana 0.38

10. Pagurus longicarpus 0.32

11. Euceramus praelongus 0.22

12. Emerita talpoida 0.21

13. Pinnotheres maculatus 0.21

14. Panopeus herbstii 0.17

15. Callianassa biformis 0.13

16. Palaemonetes spp. 0.11

17. Libinia spp. 0.09

18. Ovalipes ocellatus 0.08

19. Pagurus pollicaris 0.05

20. Pinnixa cylindrica 0.05

21. Eurypanopeus depressus 0.04

22. Xiphopenaeus kroyeri 0.03

23. Ogyrides alphaerostris 0.03

24. Polyonyx gibbesi 0.03

25. Naushonia crangonoides 0.02

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 52

Table 7. continued.

26. Pinnixa sun. 0.02

27. Rhithropanopeus harrisii 0.02

28. Alpheus heterochaelis 0.01

29. Callianassa atlantica 0.01

30. Sesarma cinereum 0.01

31. Cancer irroratus <0.01

32. Trachypenaeus constrictus <0.01

33. Cranson septemspinosa <0.01

34. Ocypode quadrata <0.01

35. unknown A <0.01

36. Penaeus spp. <0.01

37. unknown B <0.01

38. Hippolyte pleuracantha <0.01

39. Sesarma reticulatum <0.01

40. Alpheus normanii <0.01

41. Cancer borealis <0.01

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 53

(1.08%). A classification for the 41 species is contained in Appendix

D. Information concerning known ranges and habitats can be found 'n

Williams (1965, 1984).

Of the 160 developmental stages, 56 were found in sufficient quan

tities for analysis. Approximately a 0.03% of total catch level was the

critical value for further stage consideration. Table 8 contains per

cent of total catch according to stage of development. Zoeae I, II and

III of C. sapidus were the most commonly encountered stages at 54.72,

26.05 and 5.01% of total catch, respectively. Zoea II and the postlarva

of Uca spp. were next at 1.46 and 0.96%, respectively. Complete devel

opmental stage distributions by station and light-depth are listed in

Appendix E and F, respectively.

Vertical Distribution Groups

Fifteen different patterns of vertical distribution were discerned

based on comparisons of Spearman rank correlation coefficients for the

56 stages at the five depths sampled. 1540 possible stage combinations

were tested but individual results were not included due to space limi

tations. Larvae and postlarvae with similar vertical distributional

patterns were grouped in Table 9. Absolute significant correlations at

all depths were not always necessary for inclusion in a given group.

For example, if stages A-C and B-C were correlated, then A-B were also

included in the group with stage C, even though A-B were not completely

correlated. In most of these cases, significant coefficients were

obtained at four of the five depths, with p slightly >0.05 at the other

depth. Within a given group, the most abundant stage was selected for

further testing.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54

Table 8. Overall percent of total catch by stage of development; Roman numerals = zoeal stages, PL = postlarva.

Species Stage %

1. Callinectes sapidus I 54.72

2. Callinectes sapidus II 26.05

3. Callinectes sapidus III 5.01

4. Uca spp. II 1.46

5. Uca spp. PL 0.96

6. Callinectes sapidus PL 0.89

7. Hexapanopeus angustifrons I 0.79

8. Pagurus annulipes I 0.74

9. Pinnixa chaetopterana II 0.73

10. Upogebia affinis I 0.68

11. Uca spp. III 0.51

12. Callinectes sapidus IV 0.42

13. Pinnixa chaetopterana I 0.42

14. Hexapanopeus angustifrons II 0.39

15. Pinnixa chaetopterana III 0.39

16. Pagurus annulipes II 0.36

17. Pinnotheres ostreum II 0.34

18. Neopanope savi I 0.32

19. Pinnotheres ostreum I 0.31

20. Uca spp. I 0.30

21. Upogebia affinis II 0.22

22. Pagurus annulipes III 0.20

23. Pagurus longicarpus I 0.19

24. Hexapanopeus angustifrons III 0.17

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 55

Table 8. continued.

25. Pea spp. IV 0.16

26. Neopanope sayi II 0.16

27. Pinnixa chaetopterana IV 0.14

28. Panopeus herbstii I 0.13

29. Euceramus praelongus I 0.13

30. Pinnotheres ostreum III 0.12

31. Pinnixa sayana II 0.11

32. Upogebia affinis III 0.10

33. Pinnotheres maculatus I 0.10

34. Pinnixa sayana I 0.10

35. Euceramus praelongus II 0.09

36. Pagurus longicarpus II 0.09

37. Pinnixa sayana III 0.09

38. Libinia spp. I 0.09

39. Callinectes sapidus V 0.08

40. Upogebia affinis IV 0.07

41. Callinectes sapidus VI 0.07

42. Emerita talpoida II 0.07

43. Emerita talpoida III 0.06

44. Uca spp. V 0.06

45. Pinnixa chaetopterana V 0.06

46. Hexapanopeus angustifrons IV 0.06

47. Pinnotheres maculatus II 0.05

48. Callianassa biformis I 0.05

49. Emerita talpoida I 0.05

50. Pinnixa sayana IV 0.05

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 56

Table 8. continued.

51. Pinnotheres ostreum IV 0.04

52. Callinectes sapidus VII 0.04

53. Pagurus pollicaris I 0.04

54. Ovalipes ocellatus II 0.04

55. Callianassa biformis II 0.04

56. Pagurus longicarpus III 0.03

57. Palaemonetes spp. II 0.03

103 other stages 0.83

TOTAL 100

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 57

Table . Stage groupings based on significant Spearman rank correla tions at all depths sampled, * = most abundant stage used as group example for further discussions.

Group Station Stages

1 York Uca spp. I, II*

2 York Uca spp. Ill*, IV, V, PL; Callinectes sapidus PL

3 York Upogebia affinis I, II; Neopanope sayi I, II; Hexapanopeus angustifrons I, II; Pinnixa sayana II, III; Pinnotheres maculatus I, II; Pinnotheres ostreum I; Panopeus herbstii I; Palaemonetes spp. II; Euceramus praelongus II; Pinnixa chaetopterana I, II*, III, IV

4 bay Callinectes sapidus I

5 bay Callinectes sapidus PL, Uca spp. PL*

6 bay Uca spp. II

7 bay Uca spp. Ill*, IV, V

8 bay Pinnixa chaetopterana I, II, III, IV, V; Pinnixa sayana I, II, III; Pinnotheres ostreum I. II, III, IV; Pinnotheres maculatus I; Hexapanopeus angustifrons I*, II, III, IV; Neopanope sayi I, II; Pagurus longicarpus I, II, III; Upogebia affinis I, II, III, IV; Callianassa biformis I, II

9 bay Euceramus praelongus I

10 bay Euceramus praelongus II

11 ocean Callinectes sapidus I

12 ocean Callinectes sapidus II*. Ill, IV

13 ocean Callinectes sapidus V*. VI, VII

14 ocean Callinectes sapidus PL

15 ocean Emerita talpoida I, II, III; Libinia spp. I; Hexapanopeus angustifrons II, III; Pagurus annulipes I*, II, III; Ovalipes ocellatus II; Pagurus longicarpus II; Upogebia affinis II; Pagurus pollicaris I

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 58

As spatial distribution (Hoi) was previously discussed, the hypo

thesis concerning depth differences (Ho2) was initially tested using

group results. Appendix C (Table C-6) contains test results for

Kruskal-Wallis using depth and group distributions. Ho(l) was accepted

for groups 1, 2, 4-6 and 13 without a consideration of light conditions.

Figure 7 contains day-night percent of total catch with depth for

each group. As with collective larval and postlarval considerations,

Ho(3) was subdivided into Ho(3a) (day-night depth) and Ho(3b) (day-night

density) for group considerations. Appendix C (Table C-6) also shows

results which indicate that daylight differences in depth distribution

occur in groups 3-12 and 15 and at night in groups 2-3, 5-7, 11-12 and

14. Ho(3a) was formally rejected for every group except 10, 11 and 13

(see Appendix C, Table C-7). Differences in day-night neuston distribu

tions were especially evident. Group 7 exhibited significantly differ

ent day-night distributions at all sampled depths. Ho(3b) was investi

gated using the Mann-Whitney test (Appendix C, Table C-8). The null

hypothesis was accepted for all groups except 5 and 7.

Mann-Whitney test results for group distributions along with mean

densities can be found in Appendix C (Table C-9). Significant differ

ences in day-night mean depth were obtained for all groups except 1, 4,

10, 13 and 15. A representation of day-night variations in group

weighted mean depths is contained in Appendix C (Figure C-2).

Again, Ho(4) (tidal differences) was split into Ho(4a) (tidal depth

variations) and Ho(4b) (tidal density variations). Ho(4a) was tested

using the Kruskal-Wallis test in comparisons of depth distribution

according to weighted mean depth variations with light and tides.

Ho(4a) was accepted for all groups for total tides and tides divided

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure 7 Percent of total catch with depth, day-night, groups. A-C = York River mouth; D-J = Chesapeake Bay mouth; K-0 offshore.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

N.S. (3.19) (1.96) (p<0.05)

CALLINECTES SAPIDUS I DAY % NIGHT % DAY DAY % NIGHT % U.

YORK YORK RIVER MOUTH CHESAPEAKE BAY MOUTH ET () ET (m) DEPTH B. GROUP 2. UCA spp. IH (m) DEPTH D. D. GROUP 100

N.S. (7.62) (2.67) (p < 0.05) < (p

DAY DAY % NIGHT % DAY DAY % NIGHT % (9.71) YORK YORK RIVER MOUTH YORK YORK RIVER MOUTH C. C. GROUP 3. PINNIXA CHAETOPTERANA H A. A. GROUP 1. UCA spp. H E E X CL LD O x h* Q. LU Q

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

(3.37) (1.87) (p<0.01) (p<0.001)

DAY DAY % NIGHT % DAY % NIGHT % (6.63) (6.59) CHESAPEAKE BAY MOUTH CHESAPEAKE BAY MOUTH H. H. GROUP 8. HEXANOPEUS ANGUSTIFRONS I F. F. GROUP 6. UCA spp. IE

E E x x t— Q. i— CL LU Q UJ Q (1.31) (p<0.001) (3.38) (p < 0.02) < (p

) 12 . DAY DAY % NIGHT % DAY DAY % NIGHT % 8 ( (5.75) CHESAPEAKE BAY MOUTH CHESAPEAKE BAY MOUTH G. G. GROUP 7. UCA spp. PL E. E. GROUP 5. UCA spp. D E E X t- h- Q. Q. UJ Q Ill O

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.

) N.S. 02 . (5.70) 1 ( (p <0.05) ) 66 DAY DAY % NIGHT % DAY DAY % NIGHT % . (7.01) 1 (

OFFSHORE CHESAPEAKE BAY MOUTH ET () ET (m) DEPTH J. GROUP 10. EUCERAMUS PRAELONGUS H (m) DEPTH L. GROUP 12. CALLINECTES SAPIDUS 100

) 11 . U .53) 1 {p = 0.02) = {p ( (p < 0.05) (p < ) 11 DAY DAY % NIGHT % DAY DAY % NIGHT % . 12 CHESAPEAKE BAY MOUTH OFFSHORE I. GROUP 9. EUCERAMUS PRAELONGUS I K. K. GROUP 11. CALLINECTES SAPIDUS I E E x H- O. UJ Q a. a UJ

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. NJ O'

(8.58) (p= 0.02) (p= NIGHT % (1.17) DAY %

OFFSHORE NIGHT % N. N. GROUP tt. CALLINECTES SAPIDUS PL E X t— CL Q UJ DAY DAY %

V N.S. NIGHT % OFFSHORE 0. 0. GROUP 15. PAGURUS ANNULIPES I E t— UJ Q Q. DAY % (0.85) (2.19) OFFSHORE M. M. GROUP CALLINECTES 13. SAPIDUS o UJ

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 63

into day-night. Appendix C (Table C-6) lists various significant dif

ferences in vertical distribution by comparing distribution with depth

at given tidal phases. Ho(4b) was likewise tested using Kruskal-Wallis

methods. Ho(4b) was accepted for all groups (Appendix C, Table C-8).

Ho(3) (light differences) and Ho(5)-Ho(10) concerning variations in

group distributional patterns according to environmental parameters were

tested using Spearman rank correlation (Appendix C, Table C-10). Sig

nificant positive correlations were found between distribution and light

(night) for all groups, especially at the neuston depth. Significant

coefficients were obtained between night and all depths for group 5.

Thus, Ho(3) was rejected for all groups. Significant inverse correla

tions with temperature occurred at various depths for groups 4, 6-8 and

15. Positive correlations with temperature were found in groups 5, 11-

15. Ho(5) (temperature variations) was accepted for groups 1-3 and 9,

while Ho(6) (salinity differences) was accepted for groups 2, 4-9.

Significant positive correlations with salinity were noted in groups 1,

3, 10-15; inverse correlations in groups 1 and 13. Significant correla

tions with wind direction were found in groups 7, 8, 10-14. The null

hypothesis was accepted for wind direction (Ho7), groups 1-6, 9-15; wind

speed (Ho8), groups 1-2, 4, 7-12, 15; cloud cover (Ho9), groups 2-3, 5,

7, 11-15; and sea state (HolO), groups 1, 4-5, 8, 10-12.

Inter- and intra-specific variations in vertical distribution

(Holl-Hol2) can be found in Table 9. Ho(ll) (similar stages show no

distributional differnces) was rejected. Ho(12) was likewise rejected

with various groups containing different stages of the same species.

The possibility of diurnal vertical migration (Hol3) was tested

using time series analysis, specifically; auto-correlation and cross-

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correlation with light. Ho(13) was accepted for the following groups:

1, 3, 4, 10-15 (see Appendix C, Figure C-3).

Dispersal-Recruitment Patterns

Six dispersal-recruitment patterns were discerned after examination

of group results, spatial distributions (Appendix E), previous litera

ture findings and adult habitats (Williams, 1965, 1984) (see Table 10).

All genera collected were included, even those found in low concentra

tions. Patterns of rarely obtained genera were based partly on avail

able information and partly on speculation. Each retention pattern

overlaps another one in a progression from estuarine to transitional to

offshore locations. Expulsion/immigration patterns were based partly on

where spawning occurs and distance of offshore dispersal (Callinectes is

transported to at least 50 miles offshore, while Uca is dispersed mainly

to about 20 miles, Maris and Mcconaugha, 1983; McConaugha et al., 1983).

1. Retained Estuarine Species

About 24% of collected species were classified as "retained estua

rine" recruitment pattern, in which approximately 80% of the catch were

obtained from the York River station. Two distributional groups were

included with this pattern. Group 3 (mean depth day-night = 9.71-7.62 m,

p < 0.05) and group 8 (6.59-3.37, p < 0.001). Diurnal vertical migra

tion occurred in group 8.

a. Alpheus heterochaelis Say

Apheus heterochaelis was the 28th most commonly collected species

(0.01% of the total). Zoeal stages I, II, III, V and VI were collected

(74% were stage I) with 93% from the York River mouth. Maximum density

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Xiphopenaeus Spawning Expelled Callinectes Transitional Spawning Uca Expelled Estuarine Naushonia Ocypode Libinia Retained Offshore (20-70-10) (0-15-85) York) (>60% ocean) (>90% Trachypenaeus Cancer Penaeus Pagurus Ovalipes Nearshore Hexapanopeus Retained Transitonal- Rhithropanopeus Upogebia Hippolyte Crangon Callianassa Euceramus Emerita Retained Estuarine- Transitional to approximate to mean % catch of per station - bay (York - ocean); genera below the below dotted the were line collected in numbers low and placed partly on speculation. (80-20-0) (35-60-5) Polyonyx Sesarma Eurypanopeus Ogyrides Alpheus Palaemonetes Pinnixa Panopeus Pinnotheres Neopanope Estuarine Retained Table 10. Table 10. Dispersal-recruitment patterns by genera. Numbers in parentheses refer

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•was 2.238 per cubic meter (ZI-York-EB-night) (stage-station-depth-

light). During the day, 50% of the catch were from 3 m (100% 3 m, and

below). At night 63% were collected from 6 m and below.

b . Alpheus normanii Kingsley

Alpheus normanii was the 40th most commonly collected species

(<0.01% of the total). Zoeal stages II and III were obtained (84% were

stage II) with 100% from the bay mouth. Maximum density was 0.173 per

cubic meter (ZI-bay-N-day). During the day, 100% were from the epiben-

thic and at night 100% were collected from the neuston.

c. Eurypanopeus depressus (Smith)

Eurypanopeus depressus was the 21st most commonly collected species

(0.04% of the total). Zoeal stages I-III were obtained (56% were stage

I) with 88% from the York River mouth. Maximum density was 12.023 per

cubic meter (ZI-York-N-night). During the day 76% of the catch ranged

from 3-6 m, at night 55% were collected from the neuston.

d. Neopanope sayi (Smith)

Neopanope sayi was the 8th most commonly collected species (0.51%

of the total). Zoeal stages I-IV and a postlarval stage were obtained

(62% were stage I) with 80% from the York River mouth. Maximum density

was 87.295 per cubic meter (ZI-York-1 m-day). During the day, 54% were

from 1 m. At night, 67% were collected from the neuston.

e. Ogyrides alphaerostris (Kingsley)

Ogyrides alphaerostris was the 23rd most commonly collected species

(0.03% of the total). Zoeal stages I-VII were obtained (35% were stage

I) with 81% from the York River mouth. Maximum density was 1.983 per

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cubic meter (ZIII-York-1 m-night). During the day 62% of the catch were

from 6 m (100% at 3 m or below). At night 55% were collected from the

epibenthic layer.

f. Palaemonetes spp.

Palaemonetes spp. was the 16th most abundant species (0.11% of the

total). Zoeae I-VII and the postlarva were obtained (29% were stage II)

with 79% from the York River mouth. Maximum density was 7.672 per cubic

meter (ZII-York-N-night). During the day 57% were found from 3-11 m. At

night 78% were from the neuston.

g. Panopeus herbstii H. Milne-Edwards

Panopeus herbstii was the 14th most commonly collected species

(0.17% of the total catch). Zoeae I-IV and the postlarva were obtained

(81% were stage I) with 87%from the York River mouth. Maximum density

was 81.060 per cubic meter (ZI-York-1 m-day). During the day 78% of the

catch was from 1 m, while at night 59% was from the neuston.

h. Polyonyx gibbesi Haig

Polyonyx gibbesi was the 24th most commonly collected species

(0.03% of the total catch). Zoeae I-II and the postlarva were obtained

(57% were stage II) with 97% from the York River mouth. Maximum density

was 2.486 per cubic meter (ZII-York-EB-day). During the day all were

collected at 3 m or below (56% epibenthic). At night 98% were located

at 3 m or below (45% epibenthic).

i. Sesarma cinereum (Bose)

Sesarma cinereum was the 30th most abundant species (0.01% of the

total). Zoeae II-IV were obtained (46% were stage II), all from the York

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River mouth. A maximum density of 2.486 per cubic meter was found (ZII-

York-EB-day). During the day 89% were located at or below 6 m, while at

night 78% were in the neuston.

j. Sesarma reticulatum (Say)

This species was rarely collected (number 39, at <0.01% of the

total). Only zoea III was obtained from the York River mouth in maximum

densities up to 0.252 per cubic meter. Larvae were collected only at

night from the neuston.

2. Retained Estuarine-Transitional Species

Species having a "retained estuarine-transitional" recruitment

pattern accounted for 30% of the total catch. The approximate percent

catch by station (York-bay-ocean) was 35-60-5. As with retained estua

rine forms, groups 3 and 8 were included.

a. Callianassa atlantica Rathbun

Callianassa atlantica was the 29th most abundant species (0.01% of

the total). Zoeae I-II were found (66% were stage I), with 99% from the

bay mouth. Maximum density was 2.029 per cubic meter (ZII-bay-EB-day).

b. Callianassa biformis Biffar

Callianassa biformis was the 15th most common species (0.13% of the

total). Zoeae I-IV and a postlarva were found (42% were stage I), with

88% from the bay mouth. Maximum density was 8.156 (ZI-bay-EB-day).

During the day 75% were found in the epibenthic while 49% of night

specimens were taken near the bottom.

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c. Crangon septemspinosa Say

Crangon septemspinosa ranked 33rd (<0.01% of the total). Zoeae I

and III, along with the postlarva were collected (57% were stage I),

with 43% from the York River mouth and 57% from the bay mouth. Maximum

concentration was 0.741 per cubic meter (PL-York-EB-night). During the

day 100% were found at 6 m, while at night 75% were in the epibenthos.

d. Hippolyte pleuracanthus (Stimpson)

This species was rarely collected (38th, <0.01% of total). Only

zoea I was found, with 100% from the bay mouth. Maximum density was

0.381 per cubic meter (ZI-bay-6 m-night). Specimens were obtained only

at night from the epibenthic depth.

e . Pinnixa chaetopterana Stimpson

Pinnixa chaetopterana was the third most abundant species (1.74% of

total catch). All five zoeae were obtained (43% were stage II), with

45% from the York River mouth and 55% from the bay mouth. Maximum

density was 68.698 per cubic meter (ZII-bay-EB-day). During the day 73%

were at the bottom, and at night 60% were in the epibenthic layer.

f. Pinnixa cylindrica (Say)

Pinnixa cylindrica was the 20th most common species (0.05% of total

catch). All five zoeae were collected (50% were stage I) with 97% from

the bay mouth. Densities up to 5.648 per cubic meter (ZI-bay-EB-day)

were found. During the day 95% were at or below 6 m and at night 39%

were in the neuston, while 30% were at the bottom.

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g. Pinnixa sayana Stimpson

Pinnixa sayana accounted for 0.38% of total catch and was the ninth

most common species. Zoeae I-V were found, with stage II accounting for

31%; 44% of the total were collected from the York River mouth, while

56% were found in the bay mouth. Maximum density was 9.814 (ZIII-bay-EB-

day). During the day 55% were at the bottom (94% at or below 6 m).

At night 49% were found in the epibenthos (64% at or below 6m).

h. Pinnixa spp.

Pinnixa spp. (postlarvae only) was the 26th most common species

(0.02% of total catch). 65% were found at the York River mouth, 35% at

the bay mouth station. A maximum density of 3.005 per cubic meter was

obtained (PL-York-EB-night) 100% were collected at or below 6 m during

the day, while 83% were found at similar depths at night.

i. Pinnotheres maculatus Say

Pinnotheres maculatus was the 13th most abundant species (0.21% of

total catch). Zoeae I-V were collected (50% were stage I), with 53%

from the York River mouth and 45% from the bay mouth. Maximum density

was 8.521 per cubic meter (ZI-bay-N-night). During the day 57% were in

the epibenthos (91% at 6 m or below). At night 42% were at the bottom

and 27% were in the neuston.

j. Pinnotheres ostreum Say

Pinnotheres ostreum was the seventh most common form (0.84% of

total catch). Zoeae I-IV and the postlarva were collected (41% were

zoea II), with 90% from the bay mouth. Maximum density was 58.656 per

cubic meter (ZII-bay-6 m-day). During the day 61% were found in the

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epibenthos (97% at or below 6 m), while at night 64% were in the

neuston.

k. Rhithropanopeus harrisii (Gould)

Rhithropanopeus harrisii was the 27th most abundant species (0.02%

of total catch). Zoeae I-IV were collected (zoea III was 48%), with 87%

from the bay mouth. Maximum density was 1.883 per cubic meter (ZIII-

bay-EB-day). During the day 52% were at the bottom (86% at or below 6

m), while at night 35% were in the neuston and 35% were found in the

epibenthos.

1. Upogebia affinis (Say)

This species was the sixth most common (1.08% of the total). Zoeae

I-IV were collected (zoea I was 62%), with 60% from the bay mouth.

Maximum density was 36.788 per cubic meter (ZI-bay-EB-night). During

the day 42% were found at 3 m, while at night 34% were in the epiben

thos.

3. Retained Transitional-Nearshore Species

Fifteen percent of the species catch was classified as having a

"retained transitional-nearshore" recruitment pattern. Station distri

bution was about 20-70-10 (York-bay-ocean). Groups 3 and 8 were in

cluded as with retained estuarine and retained estuarine-transitional

species. In addition, groups 9 (mean depth day-night = 7.42-4.53, p =

0.02), 10 (7.01-5.70, p > 0.20) and 15 (6.74-6.64, p > 0.20) were

categorized with this recruitment pattern.

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a. Euceramus praelongus Stimpson

Euceramus praelongus was the 11th most common species (0.22% of the

total). Both zoeal stages and the postlarva were collected (58% were

stage I), with 76% from the bay mouth. Maximum density was 11.066 per

cubic meter (ZI-bay-EB-day). During the day 44% were at 6 m (83% at or

below 6 m), while at night 41% were in the epibenthos (60% at or below

6 m).

b. Hexapanopeus angustifrons (Benedict and Rathbun)

Hexapanopeus angustifrons was the fourth most common form (1.42% of

total catch). All four zoeae and the postlarva were collected(56% were

stage I), with 81% of the catch from the bay mouth station. A maximum

density of 32.172 (ZI-bay-6 m-day) was obtained. During the day 66%

were found at or below 6 m, while at night 42% were in the neuston.

c. Pagurus annulipes (Stimpson)

Pagurus annulipes was the fifth most common species collected

(1.32% of the total catch). All four zoeae and the postlarvae were ob

tained (zoea I was 56%), with almost 100% from offshore. A maximum of

138.847 per cubic meter was found (ZI-ocean-1 m-night). During the day

64% were found from 3-6 m, while at night 55% were at or above 1 m.

d . Pagurus longicarpus Say

This species was tenth in total abundance (0.32% of total catch).

All four zoeae and the postlarva were collected (60% were zoeaI), with

83% found in the bay mouth. A maximum density of 14.721 per cubic meter

was obtained (ZI-bay-EB-day). During the day 64% were in the epiben

thos, while at night 27% were in the neuston and 30% at the bottom.

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e. Pagurus pollicaris Say

Pagurus pollicaris was the 19th most common form (0.05% of total

catch). Zoeae I-III were obtained (77% were stage I), with 99% from

offshore. A maximum density of 17.276 was found (ZI-ocean-N-night).

During the day 100% were at or below 6 m, while at night 49% were in the

neuston.

f. Trachypenaeus constrictus (Stimpson)

Trachypenaeus constrictus was the 32nd most common species (<0.01%

of total catch). Zoeae II-V were obtained (zoea IV was 40%), with 53%

of the catch from the bay mouth. A maximum concentration of 1.002 per

cubic meter (ZIV-York-N-night) was noted. During the day 69% were in

the epibenthic layer, while at night 59% were in the neuston.

4. Retained Offshore Species

Seventeen percent of the species were classified as having a "re-

tained offshore" recruitment pattern. Spatial distributions of about 0-

15-85 (York-bay-ocean) were noted. Group 15 was included as with re

tained transitional nearshore.

a. Cancer borealis Stimpson

A single postlarva of C. borealis was collected in the bay mouth

(3 m, night, 0.158 per cubic meter).

b. Cancer irroratus Say

Cancer irroratus was the 31st most common form (<0.01% of the

total). Zoeae I-II, V, along with the postlarva were collected (the

postlarva accounted for 39%), with 100% from offshore. A maximum den

sity of 1.664 per cubic meter was obtained (PL-ocean-3 m-day). During

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the day, 53% were at 3 m with the rest at the bottom. At night 100%

were at 6 m.

c. Emerita talpoida (Say)

Emerita talpoida was the 12th most common species (0.21% of the

total). All six zoeae and the postlarva were collected (zoeae II, III =

31%, 30%, respectively) with 82% of the total catch from offshore.

Maximum density was 46.282 per cubic meter (ZII-ocean-N-night). During

the day 90% were at or below 6 m, while at night 86% were at or above

1 m.

d. Libinia spp.

Libinia spp. was the 17th most abundant form (0.09% of total

catch). Both zoeal stages and the postlarva were obtained (91% were

zoea I), with 85% of the specimens from offshore. A maximum density of

12.896 per cubic meter (ZI-ocean-EB-night) was noted. During the day

85% were at or below 6 m, while 34% were in the neuston and 30% were

epibenthic at night.

e. Naushonia crangonoides Kingsley

Naushonia crangonoides was 25th in abundance (0.02% of the total).

Zoeae I-II were collected (83% zoea I), with 98% offshore. A maximum

density of 7.620 per cubic meter (ZI-ocean-N-night) was noted. During

the day all were at 6 m or below, while at night 58% were in the

neuston.

f. Ocypode quadrata (Fabricius)

Ocypode quadrata was 34th in abundance (<0.01% of the total). Only

stage I was found and all were at the offshore location. A maximum

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density of 1.497 per cubic meter was noted (N-night). All specimens

were collected at night in the neuston.

g. Ovalipes ocellatus (Herbst)

Ovalipes ocellatus was the 18th most abundant species (0.08% of the

total). All five zoeal stages were found (47% zoea II), with 94% from

offshore. A maximum density of 17.276 per cubic meter (ZII-ocean-N-

night) was collected. During the day 57% were in the epibenthos, while

at night 37% were in the neuston and 42% at the bottom.

5. Expelled Species with Estuarine Spawning (Uca spp.)

Uca spp., having an "expelled with estuarine spawning" recruitment

strategy, accounted for 3% of the total species. Groups 1 (mean day-

night = 4.08-2.67, p = 0.10), 2 (4.08-2.67, p <0.05), 6 (6.63-1.87, p

<0.001) and 7 (8.12-3.38, p < 0.02) were included. About 60% of total

catch came from the York River station. All five zoeal stages and the

postlarva were obtained, with stage II being dominant. A maximum den

sity of 360.705 per cubic meter was found (ZII-York-N-night). During

the day 62% were located between 1 and 3 m, while at night 80% were in

the neuston. Uca spp. was second in abundance, accounting for 3.45% of

total catch.

6. Expelled Species with Transitional Spawning

Seven percent of collected species were classified as having an

"expelled with transitional spawning" recruitment pattern. Groups 2 (as

with expelled-estuarine), 4 (mean depth day-night = 4.58-3.19, p =

>0.10), 5 (5.75-1.31, p < 0.001), 11 (2.11-1.11, p < 0.05), 12 (1.66-

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1.02, p < 0.05), 13 (0.85-2.19, p > 0.20) and 14 (1.17-8.58, p = 0.02)

were included. More than 90% of the total catch was obtained offshore.

a. Callinectes sapidus Rathbun

Callinectes sapidus dominated the collections, with 87.40% of total

catch. All 8 zoeal stages and the postlarva were obtained (63% zoea I,

30% zoea II), with 98% of the catch offshore. During the day 68% were at

or above 1 m, while at night 88% were at or above 1 m.

b. Penaeus spp.

Penaeus spp. accounted for <0.01% of the total catch and was ranked

36th in abundance. Only zoea I was collected, all from offshore, epi-

benthic, during the day. A maximum density of 0.988 per cubic meter was

obtained.

c. Xiphopenaeus kroyeri (Heller)

Xixopenaeus kroyeri was the 22nd most common species (0.03% of the

total catch). Zoeae I-III, V-VII and IX were obtained (44% zoea II),

all from offshore. During the day 100% were found at 6 m, while at

night 67% were at 3-6 m.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Discussion

Successful recruitment is an essential process for maintaining

stability in populations of marine organisms. Variations in vertical

positioning greatly affect the extent of retention within or expulsion

from a given location. Studies of vertical distribution have been

conducted for almost 200 years, but still very little is actually known

concerning cause and effect relationships. Investigations of decapod

larvae and postlarvae are especially few and those completed were

generally limited by length of sampling time, depths used and lack of

species and stage identifications. Much more is known about recruitment

even though extensive studies have been undertaken only for about the

last 50-60 years. However, information on actual mechanisms employed by

various species is sparse.

A major criticism of previous studies was the lack of species and

stage differentiations. However, general trends were likewise noted in

the present study. Such generalizations can be especially useful when

coupled with species and stage variations for an overall examination.

If used alone, generalizations can lead to misconceptions. For

instance, diurnal vertical migration was found to occur collectively at

the bay mouth station, but only certain species and stages were

involved.

Also, the hierachy of dominant species in the present study is

biased due to seasonality. Most species collected in large numbers (C.

sapidus, Uca spp., Pinnixa spp., H. angustifrons') are present mainly

from spring until early autumn, with late summer peaks. During winter

and spring, other species (Crangon septemspinosa. Cancer irroratus) are

the dominant larval decapods within the study area.

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Spatial distribution was found to be extremely important in affect

ing vertical distribution of the same or similar stages. Significant

Spearman rank correlation coefficients were not obtained at all depths

(0, 1, 3, 6, 11-13 m) for any comparison among the three stations.

Distributional patterns were significantly similar at all stations for

the neuston layer.

Results of the present study support previous findings concerning

the importance of the neuston layer (Smyth, 1980; Johnson, 1982;

Provenzano et al., 1983a). However, as opposed to previous studies in

which 90-99% of the total catch of one species was neustonic (Provenzano

et al., 1983b), the contribution from the neuston for multiple species

was much less. Percentages of total catch from the neuston (and upper 3

m) for the York River mouth, bay mouth and offshore stations in the

present study were 41.39% (68.61%), 31.91% (45.89%), and 33.61%

(96.23%), respectively. All previous studies sampled largely during

daylight hours only and at widely separated stations during the same

day. Thus, distributional changes at a given location with time were

not observable. The neuston is unquestionably important for decapod

larval and postlarval distribution but conclusions based on diurnal

variations over time, as in the present study, show that significant

changes occur with depth during the cycle and at different spatial

locations. Distribution studies that neglect diurnal variability can be

misleading.

Longhurst (1976) stated that the sea surface and bottom were ex

tremely important as obvious barriers to vertical migration. In the

present study, 21.90%, 35.08%, and 0.70% of total catch was epibenthic

for the three stations (York, bay, ocean), respectively. Thus, the

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boundaries must be considered as larval concentrating sites. The low

numbers at the bottom offshore seem to indicate that vertical position

ing is influenced by behavioral and/or passive factors in addition to

the barrier effect.

From an overall viewpoint, a wider range of vertical changes oc

curred at the bay mouth station than at the York River mouth and off

shore stations. A mean daytime depth of 7.49 m was noted for bay mouth

species, with a significant movement to 3.19 m at night. Fluctuations

in vertical positioning at the bay mouth location likely facilitate

behavioral modifications for retention or expulsion in the bilayered

system. Net outflow of low salinity water occurs at the surface, with

net inflow of higher salinity water near the bottom. Bousfield (1955)

speculated that barnacle larvae near the surface were expelled from a

Canadian estuary, while larvae closer to the bottom were more likely

retained, irrespective of tidal flow patterns. Likewise, Sandifer

(1973b) and Cronin (1979) postulated similar effects of vertical posi

tioning for various stages of crab larvae in the Chesapeake Bay,

Virginia and Newport River estuary, North Carolina, respectively.

Offshore, the larvae and postlarvae were generally distributed much

closer to the surface than at the other stations. Day and night mean

depths were 1.86 and 1.41 m, respectively, which was an insignificant

difference. Previous large-scale near-surface distributions for off

shore decapod larvae were noted by Smyth (1980), Johnson (1982), Maris

and McConaugha (1983) and Provenzano et al. (1983b). Wind-driven circu

lation becomes much more important as stages are concentrated near the

surface. Southern and Gardiner (1932) initially proposed wind-induced

effects on surface distribution of cladocerans and copepods in Lough

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Derg, Ireland. More elaborate wind-models for offshore circulation of

blue crab larvae (C. sapidus) were recently proposed by Johnson et al.

(1984) and Johnson (1985b). Wind-induced circulation is a viable mecha

nism for retention of larvae in a large-scale system. Others have

speculated as to the importance of immigration from offshore via bottom

currents (Boicourt, 1982; Sulkin and Van Heukelem, 1982; Brookins and

Epifanio, 1985). Obvious arguments against bottom immigration in the

Chesapeake Bay region are the low numbers of postlarvae at the bottom as

found in the present study and previous ones (Johnson, 1982; Maris and

McConaugha, 1983; Provenzano et al., 1983b), as well as the extremely

slow flow patterns of near-bottom water off the Chesapeake Bay mouth

(Boicourt, 1981).

A large number of species in the York River estuary remained near

the bottom, while others varied their vertical position diurnally. Day-

night mean depths were not statistically different (5.96-4.24 m) for

this group. Sandifer (1973b) also found near-bottom distributional

patterns for several species of larval shrimps and crabs at the same

location. In addition to near-bottom distribution and vertical migra

tion on flood tides, both of which promote retention, short-term migra

tions to a depth of zero net motion are important for estuarine reten

tion. Evidence was provided for freshwater cladocerans and copepods

(Woodmansee, 1966b), and marine crab larvae (Cronin, 1979). The small-

scale vertical variations noted at the York River station could well

have represented migrations around the depth of zero net motion which

facilitates retention.

For a bilayered estuary such as the Chesapeake Bay, remaining near

the surface would aid in flushing from the system, while positioning

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. closer to the bottom enhances transport into the estuary. A general net

inflow of water occurs in the vicinity of the bay mouth at depths below

about three meters due to the salt wedge (Boicourt, 1981). Thus, any

organism with a net mean depth of at least three meters would tend to be

retained, irrespective of possible short-term vertical changes to shal

lower depths. Therefore, most larvae with mean day and night depths of

7.49 and 3.19 m, respectively probably were retained. Only those stages

with net near-surface distribution or shallow vertical positioning

during ebb tides would tend to be flushed from the system. Most stages

in the York River estuary employed various retention mechanisms, while

stages offshore remained near-surface where wind-driven circulation

allowed eventual reinvasion of the estuary.

Boicourt (1982) provided a mechanism whereby exported blue crab

larvae (C. sapidus) could be redistributed near the Chesapeake Bay mouth

for recruitment. Wind-induced circulation on the inner shelf region can

result in a mean northward flow, while offshore areas exhibit a mean

southward flow driven by pressure gradients associated with interior

circulation. The larvae flushed from the bay are entrained in a

southerly moving low salinity plume and are possibly returned by north

ward flowing inner shelf waters.

As in numerous previous studies (see Baylor and Smith, 1957 for

examples), light was the major environmental variable correlated with

vertical distribution. Cyclic diurnal vertical migration (with about a

12 hour periodicity) was noted for certain stages. These followed the

pattern of Cushing (1951) having a sharp peak in near-surface density

following sunset, a slight dip at midnight and a lesser peak near dawn.

Daytime neuston concentrations of near zero quickly increased to several

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hundred organisms per cubic meter at the sampling period just after

sunset for both York River and bay mouth locations. The near-surface

increases were accompanied by equally dramatic decreases in numbers with

depth (especially at the bay mouth location). At midnight, surface

densities decreased significantly.

Cushing (1951) proposed general inactivity with passive sinking

following active swimming and feeding, as the cause of the "midnight

dip". In the present study as in Cushing's presentation, a lesser peak

occurred just prior to dawn as energy obtained from early night feeding

was possibly depleted. Following the typical pattern, numbers increased

at depth with full sunlight. Day-night changes in concentrations were

particularly spectacular in the neuston layer, possibly aiding some

species in rapid offshore transport at night.

An uneven distributional pattern, due to about 14 hours of light

and ten hours of darkness, might aid in retention. Therefore, even if

diurnal vertical migration takes place, retention may be occurring as

more time is spent near the bottom.

Overall, variations in vertical positioning are likely combinations

of predator-prey interaction and dispersal-recruitment strategies. Lar

val survival is critical for subsequent recruitment, therefore dispersal

of larvae over a wide vertical distance aids in protection and also

enhances horizontal spreading. Survival largely depends on predator-

prey activities. Therefore, larvae likely vary their vertical position

ing in response to the patchy distribution of food items, while also

attempting to avoid predators (Kerfoot, 1970; Longhurst, 1976; Lampert

and Taylor, 1985).

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Probably the most important finding of the present study was the

general lack of correlation between tidal influence and vertical distri

butional patterns. Both the York River and bay mouth were sampled

during neap tides, but any tidal effects (other than hatching rhythms)

should have been evident, if present. No significant differences in

day, night, or combined distributional patterns were found for any tidal

phase at either the bay mouth or York River mouth locations. Offshore

tides are apparently too weak and variable to have a strong influence on

distribution (D. R. Johnson, personal communication). Larval abundance

correlations with ebb tides (promoting flushing) and flood tides (pro

moting retention) were recently presented by Cronin and Forward (1982),

Lambert and Epifanio (1982) and Brookins and Epifanio (1985). The

previous studies were conducted in small bays or inlets, and the pattern

does not seem to hold for larger estuaries, such as the Chesapeake Bay

system. This finding has significant implications because the general

ized recruitment patterns based on small inlet results can therefore be

misleading. Conversely, tidal hatching rhythmicity has been documented

for larvae of C. sapidus in the Chesapeake Bay with nighttime ebb tides

(Provenzano et al., 1983b). Various species of fiddler crabs (Uca spp.)

have also been shown to have hatching rhythms that correlate with tidal

activity (Wheeler, 1978; Zucker, 1978; DeCoursey, 1979, 1980, 1981;

Bergin, 1981; Christy, 1982; Forward et al., 1982; Salmon et al., 1985).

Other environmental parameters were poorly correlated with vertical

distribution and were presumed to be insignificant. Apparent inverse

correlations of larval densities with temperature near the surface were

mors likely associated with reduced thermal radiation and not tempera

ture fluctuations. Correlations with salinity possibly reflected weak

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affinities of larvae for certain water flow patterns, but no significant

trends were noted. Johnson (1982) documented the importance of the

pycnodine on vertical distribution in a seasonal study. Brachyuran

postlarvae were typically distributed either above or below the pycno-

cline but concentration at the pycnodine itself was not observed. Such

density gradients are obviously significant at certain locations and

times but no pycnoclines were observed in the present study. Possibly

the lack of pycnoclines was due to wind-induced mixing.

No significant correlations of vertical distribution were noted

with wind direction and speed, cloud cover, or sea state. Obviously,

wind speed and direction directly affects sea state, which in turn

influences near-surface mixing. Offshore, winds were stronger than for

the other stations which might be a reason for increased numbers at 1

and 3 m (47.54 and 15.08%, respectively). York River and Chesapeake Bay

mouth percentages at 1 and 3 m were 16.65, 10.57% and 5.25, 8.73%,

respectively. Possibly also due to wind-mixing, the 1 m depth offshore

produced a larger percentage of the total catch than the neuston (47.54,

33.61%, respectively). The neuston dominated at the other stations.

The patchy distribution of food organisms might also be a factor in

concentrations at depth.

The fifteen significantly different distributional patterns re

flected wide-spread variations among different species and developmental

stages. Similar findings were made by Sandifer (1973b, 1975), Goy

(1976), Dittel and Epifanio (1982), Maris and McConaugha (1983) and

McConaugha et al. (1983). Nevertheless, early stages of a species or

groups of related species generally displayed similar patterns of dis

tribution, while positioning of later stages differed significantly from

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early stages. Postlarvae usually exhibited their own unique distribu

tions. These variations possibly reflect different roles in the trans

port process for various stages. Early larvae are typically diffused

from hatching sites, while later stages (especially postlarvae) function

in recruitment.

Ontogenetic vertical migrations were documented for various

species, but the pattern of increased depth with age found by Bousfield

(1955), Sandifer (1973b), Goy (1976) and Lough (1976) did not generally

occur. The reverse pattern was especially evident for C. sapidus, as

previously found by McConaugha et al. 1983, in which later stages showed

an increased affinity for surface layers. Distributional patterns such

as they noted during daylight conditions, may differ significantly from

those observed over several diurnal cycles.

Retained Species

The dominant recruitment strategy of decapod crustaceans in the

vicinity of the Cheapeake Bay is retention as illustrated by 90% of col

lected species and 86% of the stages. However, variations in retention

mechanisms occur at the species and stage levels. Sandifer (1975)

proposed retention and immigration as the major recruitment mechanisms.

Johnson (1982) further divided these into retained estuarine, expelled

estuarine, and retained coastal for certain brachyuran postlarvae. Re

sults of the present study seem to indicate the need for further subdi

vision based on larval and postlarval stages of brachyurans, anomurans,

thalassinideans and shrimps. In general, larval distributions are

strongly maintained near the habitats of adult members of the popula

tion. Four retention patterns were established based on spatial distri-

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butions and vertical positioning of the larvae in relation to adult

habitats. The patterns included: retained estuarine, retained estua-

rine-transitional, retained transitional-nearshore and retained off

shore. The three proposed mechanisms of retention were maintenance of a

vertical position low in the water column without vertical migration,

undergoing vertical migration to maintain horizontal positioning and

maintaining an intermediate depth without vertical migration.

1. Retained Estuarine Species

Retained estuarine species included: Neopanope sayi, Palaemonetes

spp., Panopeus herbstii, and speculatively Alpheus heterochaelis. A.

normanii, Eurypanopeus depressus. Ogyrides alphaerostris, Polyonyx

gibbesi, Sesarma cinereum, and S. reticulatum. In general, 79 to 100%

were obtained from the York River station. Certain species were found

almost exclusively near the bottom (A. heterochaelis. A. normanj j, 0.

alphaerostris, P. gibbesi). Other species were located at mid to shal

low depths during the day and near-surface at night (E. depressus, N.

sayi, Palaemonetes spp., P. herbstii, S_. cinereum, £. reticulatum). I

propose that the group of near-bottom dwellers maintain their depth

without significant variations in vertical positioning. Close proximity

to the bottom facilitates estuarine retention via net inward flowing

bottom currents. Species such as Palaemonetes spp. and J?. herbstii

likewise maintain a typical upper mid-depth level by movements to the

depth of zero net motion to aid in retention. Other species including

N. sayi actively engage in diurnal vertical migration.

Sulkin et al. (1983) investigated the behavioral basis of depth

regulation by larvae of E. depressus. Zoea I larvae were found to be

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negatively geotactic and positively phototactic which would tend to keep

them near the surface. Early stages were in upper water layers only at

night in the present study. In contrast, N_. sayi larvae and postlar

vae were mainly collected from the bottom (Sandifer, 1972, 1973b; Goy,

1976; Johnson, 1982). As with present findings, Dittel and Epifanio

(1982) found larval stages I-IV commonly near the surface. Almost 100%

of the present study catch was within the Chesapeake Bay system, with

86% of stage I from the York River. Johnson (1982) concluded that N.

sayi was a retained estuarine species with 97% collected from the

estuary.

Sandifer (1972) stated that 79.3% of his total catch of

Palaemonetes spp. came from the bottom with stages I-III being common.

In the present study seven larval and the postlarval stage were col

lected, with 77% being stages I-III. Unlike Sandifer who collected

only during the day, these samples showed a variation in depth over the

diurnal cycle. During daylight hours mid-upper depths were typically

inhabited, while at night, 74-85% of the catch was from the neuston.

Several studies of photo- and geotaxis have been conducted with

larvae of P. herbstii (Sulkin, 1973, 1975; Forward, 1977; Bardolph and

Stavn, 1978). Results indicated that all zoeal stages were positively

phototactic and negatively geotactic with the responses reversed for the

postlarva, which corresponds well with present study findings. Sandifer

(1972) found few differences between surface and bottom distribution

patterns, but again Sandifer collected only during the day and with a

much smaller sampling device. Thus in Sandifer’s study, increased

avoidance was a viable possibility in explaining deviations from pres

ent results. As with N. sayi, Johnson (1982) found postlarvae of P.

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herbstii mostly within the estuary (92%), in collections from the lower

bay and near the bay mouth. In the present study, 96% of stage I were

obtained from the York River mouth and 98% of postlarvae were collected

at the bay mouth station. Thus, P. herbstii seems to have a broader

horizontal distributional pattern than does N. sayi. but low numbers of

late stage larvae of both species possibly influenced results obtained.

Previous studies of distribution of P. gibbesi have noted an affin

ity for the bottom. Sandifer (1972) collected 79. 5% from the bottom in

the Chesapeake Bay, while Goy (1976) found larvae exclusively at the

bottom in the same location. At offshore Mississippi stations, Maris

(1980) obtained 94% of larval JP. gibbesi from bottom samples. The

absence of vertical migration in this species confirms their benthic

affinity.

Larvae of S. cinereum and S. reticulatum were only rarely col

lected. The surface affinities obtained at night in the present study

do not reflect findings by others, who obtained most specimens from the

bottom (Sandifer, 1972; Goy, 1976). In both previous studies, very low

numbers were also collected, thus making it difficult to assess the

vertical position of these species.

2. Retained Estuarine-Transitional Species

Retained estuarine-transitional species included: Callianassa

biformis, Pinnixa chaetopterana, JP. sayana, Pinnotheres maculatus, P.

ostreum, and Upogebia affinis. Speculative inclusions (due to low

numbers collected) in this group included: Callianassa atlantica,

Crangon septemspinosa. Hippolyte pleuracanthus, Pinnixa cylindrica.

Pinnixa spp., and Rhithropanopeus harrisii. Bay mouth sampling

accounted for 45-90% of total catch (mean 60%), with up to 35% from the

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York River mouth and 5% offshore. Thus, distribution for retained

estuarine-transitional species is somewhat less restricted than for

retained estuarine. The low numbers of offshore larvae likely indicate

leakage from the estuarine system and not near-shore retention. As with

retained estuarine species, similar vertical mechanisms are employed for

retention. In the York River location, JP. chaetopterana. JP. savana, JP.

maculatus, JP. ostreum and U. affinis tend to be found close to the

bottom and do not undergo extensive diurnal vertical migration. In

comparison, at the bay mouth station, C. biformis, JP. chaetopterana, JP.

sayana, JP. maculatus, JP. ostreum and U. affinis tend to maintain their

mid-depth vertical positioning through diurnal vertical migration.

Sandifer (1972, 1973b, 1975) found very high abundances (up to

700.37 per cubic meter) for C. septemspinosa, especially from January

until June. Overall 59.4% were collected at the surface. Goy (1976)

reported C. septemspinosa as the dominant decapod larval form in the

Chesapeake Bay with peak abundances in February and May, and 8F 4% from

the bottom. Low numbers collected during the present study are an

indication of the strong seasonality in this species. Crangon seemed to

maintain a mid-depth position during the day with vertical migration to

near-surface layers at night.

As in the present study, species of Pinnixa were commonly found by

both Sandifer (1972, 1973b, 1975) and Goy (1976) from Chesapeake Bay

collections. Larvae of P. chaetopterana were also obtained mainly at

the bottom (81-99.6%, respectively for the two studies). Similar find

ings were noted for P. cylindrica, P. savana. Pinnotheres maculatus and

JP. ostreum in all three studies. Both Sandifer and Goy sampled only

during daylight hours and largely at stations within the bay as opposed

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to bay mouth locations. Johnson (1982) reported that Pinnixa spp. was

an expelled estuarine species with >60% of the postlarvae captured

outside of the estuary. Very few postlarvae were obtained in the pres

ent study, so firm comparisons cannot be made. However, larval distri

butions (which were lacking in Johnson's work) seem to indicate reten

tion at estuarine to transitional locations. It must be noted that

differentiation of postlarvae is not possible at present for Pinnixa, so

certain differences can possibly be attributed to species variations.

Although low numbers of R. harrisii were obtained in the present

study, an apparently much broader horizontal distribution pattern was

found as compared to previous work (Sandifer, 1972, 1973b, 1975;

Johnson, 1982; Lambert and Epifanio, 1982), but again most specimens

were taken near the bottom. In agreement with present findings, Goy

(1976) collected larvae from both bay mouth and estuarine locations.

Larvae of IJ. affinis demonstrated three patterns of vertical dis

tribution based on spatial distribution. In the York River mouth, most

were found near the bottom, in the bay mouth extensive diurnal vertical

migration was noted, while offshore, mid-depth distribution was main

tained. Therefore, retention was accomplished at each location by dif

fering methods. At estuarine stations, Sandifer (1972, 1973b, 1975)

collected most specimens from the bottom. Andryszak (1979) noted a

previous offshore occurrence for this species.

3. Retained Transitional-Nearshore Species

Retained transitional-nearshore species included: Euceramus

praelongus, Hexapanopeus angustifrons, Pagurus annulipes, P. longicarpus

and P. pollicaris. Trachypenaeus constrictus may also belong to the

group. Basically, 76-83% of this group were collected from the bay

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mouth station, with fewer (less than 20%) from the York River and more

(up to 10%) from offshore. At the York River mouth location, H.

angustifrons and E. praelongus were found consistently near the bottom;

in the bay mouth vertical migration was observed for H. angustifrons and

P. longicarpus: while offshore a constant mid-depth was maintained by H.

angustifrons, P. annulipes, P. longicarpus and P. pollicaris. In the

bay mouth stage I larvae of E. praelongus used limited diurnal verti

cal migration, while stage II maintained a constant mid-depth level.

This ontogenetic variation in vertical positioning supports the concept

of retention in the transitional zone.

In previous studies of E. praelongus distribution, larvae were con

sistently found close to the bottom: 66.4% (Sandifer, 1972, 1975), 99%

(Goy, 1976), 99.19% (Maris, 1980). All previous collections were made

during daylight hours. Other offshore occurrences for this species were

noted by Andryszak (1979), Maris (1980), and Maris and McConaugha

(1983). Presence offshore suggests variability in retention efficiency.

Both Sandifer (1972) and Goy (1976) collected H. angustifrons about

equally distributed at surface and bottom depths. In addition to the

present study, Andryszak (1979), and Maris and McConaugha (1983) col

lected offshore specimens. In the latter study, larvae and postlarvae

were found mainly from mid-depths to near the bottom. Stage TV possibly

utilized vertical migration from epibenthic to mid-depths. Johnson

(1982) classified this species as retained estuarine based on postlarval

distributions. Few postlarvae were obtained in the present study, but

the larval occurrences seemed to indicate a broader distributional

pattern.

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Species of Pagurus (P. annulipes, P. longicarpus, P. pollicaris)

have been collected offshore (Andryszak, 1979; Maris and McConaugha,

1983; Sadler, 1984), and the latter two species were commonly collected

within the Chesapeake Bay system (Sandifer, 1972, 1973b; Goy, 1976;

Sadler, 1984). Early zoeae showed a net offshore seasonal movement,

later stages reversed the pattern with maximum larval concentrations in

the near shore region (Sadler, 1984). Sadler's findings conform nicely

with the present transitional-nearshore retention pattern. Maris and

McConaugha (1983) found that larvae of P. annulipes maintained near-

epibenthic distributions offshore, with possible vertical migration by

later larval stages and postlarvae. Thus, some immigration of postlar-

vae may be occurring in addition to nearshore retention.

4. Retained Offshore Species

Retained offshore species included: Emerita talpoida, Libinia spp.

and Ovalipes ocellatus. Tentatively, Cancer borealis, C. irroratus,

Naushonia crangonoides and Ocypode quadrata were also included. The

offshore contribution to catch ranged from about 82 to 94%, with the

rest from the bay mouth. A single mechanism of maintenance at mid

depths without vertical migration is proposed. However, Maris and

McConaugha (1983) found that limited changes in vertical positioning

possibly occur offshore.

Larvae and postlarvae of C. irroratus have been commonly collected

in the Chesapeake Bay and nearby offshore waters (Sandifer, 1972, 1975;

Goy, 1976), but peak abundances typically occur in spring, which ac

counts for the lack of specimens in the present study. Johnson (1982)

classified this species and Libinia spp. as retained shelf with only 6

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and 9% of postlarvae found within the estuary, respectively. Dittel and

Epifanio (1982) found the largest catches of C. irroratus. Libinia spp.

and Ovalipes ocellatus at the surface during flood tide in the Delaware

Bay mouth. No tidal rhythms were observed in the present study. Thus

suggesting that larvae observed in Delaware Bay were associated with

shelf waters entering the system with subsequent loss on ebb. Maris and

McConaugha (1983) noted that larvae of C. irroratus and Libinia spp.

were found near the bottom during the day, while at night mid-depth

distributions were observed.

Expelled Species

About 10% of the species and 14% of the collected stages were

expelled from the estuarine-nearshore system with eventual immigration

by postlarvae or juveniles. Even though a low percentage of species and

stages were expelled, the two dominant species of late-summer were

included in this group, and they accounted for about 91% of the total

catch (Callinectes. 87%; Uca, 4%). Variations in expulsion mechanisms

were based largely on spawning female proximity to the bay mouth. Lar

vae of Uca spp. hatch in the estuary, whereas hatching of Callinectes

sapidus occurs near the bay mouth. Therefore, larvae of Uca spp. have

the additional task of getting to the bay mouth before expulsion can be

accomplished. Mechanisms used by expelled species included: mainte

nance at mid-depth without vertical migration, extensive vertical migra

tion, and maintenance near the surface with or without diurnal vertical

migration.

1. Expelled Species with Estuarine Spawning (Uca spp.)

A complex mechanism is proposed for dispersal of estuarine hatched

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larvae of Pea, with flushing out of the bay and eventual postlarval re

cruitment, In the York River mouth early stages (I-II) are distributed

at mid-depths, while later stages (III-V, PL) vertically migrate over a

restricted vertical gradient at mid-depths. In the bay mouth, early

stages exhibit extensive vertical migration while later stages also

vertically migrate but at deeper depths. Offshore, all stages were

found close to the surface. Thus after hatching, larvae apparently

utilize transport mechanisms to move successively to the bay mouth

region and then offshore. Once offshore, retention occurs by maintain

ing the larvae at mid- to upper depths for possible wind-driven redepo

sition of late zoeal stages and postlarvae near the bay mouth for re

cruitment. The abundance of late larval stages at the York River sta

tion likely indicates limited retention or immigration by late larvae.

Certain variations in distributional patterns, especially among the

stations, possibly results from species specific differences. As pre

viously noted, the three species of Uca cannot be differentiated at

present.

Hatching rhythmicity for Uca with tides was noted by DeCoursey

(1976, 1979, 1980, 1981), Wheeler (1978), Zucker (1978), Bergin (1981),

Christy (1982), Christy and Stancyk (1982), and Salmon et al. (1986).

Brookins and Epifanio (1985) found larvae of Uca common at the surface

during ebb tide while postlarvae were obtained most often near the

bottom at flood tide. Tidal rhythmicity was not noted for any stage of

Pea in the present study. Johnson (1982) also classified Uca as expel

led with 42% of the postlarvae collected in the estuary. A possible

recruitment mechanism was provided by Lambert and Epifanio (1982) with

quick flushing from the secondary estuary with larval development in

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the primary estuary (Delaware Bay). The larvae avoid transport out of

the Delaware Bay by sinking as development progresses (Dittel and

Epifanio, 1982). In comparison with the present study, initial flushing

processes seem compatible, but estuarine retention does not appear to be

the only recruitment strategy, as export onto the shelf was also noted.

2. Expelled Species with Transitional Spawning

Species in this hypothesized category included: Callinectes

sapidus and speculatively, Penaeus spp. and Xiphopenaeus kroyeri. The

proposed recruitment mechanism is as follows: After hatching near the

bay mouth, stage I is distributed at mid-depths. A previous study

documented flushing of recently hatched larvae during a nighttime ebb

tide (Provenzano et al., 1983). Once offshore, stage I vertically

migrates from about the two meter to one meter depth. Intermediate

stages (II-IV) also vertically migrate but from restricted depths of

about 1 1/2 m to 1 m. Late zoeal stages (V-VII) are evenly distributed

near the surface, without vertical migration, and postlarvae are found

mainly at the surface during the day, with significant numbers near the

bottom at night. This postlarval pattern may result from the low num

bers collected in this study and may not be a distinct distributional

pattern. In a similar study, Maris and McConaugha (1983) collected

large numbers of postlarvae at the same offshore station with 89% and

81% of total catch in the neuston layer for day and night, respectively.

Postlarvae have been hypothesized to sink with age and utilize

bottom currents for transport back to the bay (Boicourt, 1982; C. E.

Epifanio, personal communication), but such bottom transport does not

seem to be a major contributing factor as bottom currents in the area

are somewhat variable and weak (Boicourt, 1981; D. R. Johnson, personal

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 96

communication). Postlarvae returning to the bay mouth undergo vertical

migration from mid-depths to near-surface, while those in the York River

mouth likewise vertically migrate but over a restricted distance at mid

depths. Postlarvae that return to the estuary eventually metamorphose

into benthic-dwelling forms. Therefore, a gradual increase in bottom

affinity by postlarvae is not surprising.

Previously, significant numbers of larvae of C. sapidus were col

lected offshore by Nichols and Keney (1963), Dudley and Judy (1971),

Perry (1975), Smyth (1980), and Stuck and Perry (1981). Near-surface

affinities were noted for offshore larvae by Provenzano (1979),

Provenzano and McConaugha (1981), Johnson (1982), McConaugha et al.

(1983), Provenzano et al. (1983b) and Johnson (1985a). Elaborate wind-

driven circulation mechanisms for eventual transport back to the bay

mouth were hypothesized by Johnson et al. (1984) and Johnson (1985b). A

similar pattern of quick larval flushing out of Delaware Bay was de

scribed by Epifanio and Dittel (1982) with advection as the dominant

process. Epifanio et al. (1983, 1984) found zoeae I most commonly high

in the water column during ebb tide, with postlarvae up during flood

tide, but Brookins and Epifanio (1985) found no distributional pattern

with depth or tide in the mouth of Delaware Bay, similar to results of

the present study for the bay mouth station.

Perspectives

Examination of the effects of vertical distribution on larval and

postlarval dispersal and recruitment, certain patterns become evident.

Some estuarine and transitional species accomplish retention by consis

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 97

tently maintaining a vertical position near the bottom, while other

species vertically migrate over short intermediate distances, presumably

to the depth of zero net motion. Others maintain constant intermediate

depths, while other species vertically migrate over long distances.

Offshore, species typically are retained on the shelf by maintaining

intermediate depths. Tidal effects were found to be minimal. However,

larvae likely utilize the net flow patterns of the bilayered system for

transport purposes. Export mechanisms typically consist of near-surface

concentrations in the estuary, with upper layer affinities maintained

offshore. The evidence presented (and supported by an extremely large

data set) supports the concept that variation in vertical positioning is

the most important factor influencing dispersal-recruitment mechanisms

by decapod crustacean larvae and postlarvae in the vicinity of the

Chesapeake Bay.

Future Considerations

During the course of most studies, more questions are generated

than answers. The present study is no exception. Much information is

still needed for a better understanding of the role of vertical migra

tion in dispersal-recruitment mechanisms. A high priority would be a

seasonal study of variations in vertical positioning and species compo

sitions with time. The possible influence of tides on vertical distri

bution needs additional investigation. Sampling at a variety of loca

tions with differing amounts of tidal flushing and at different times in

the lunar tidal cycle (spring, neap tides) should prove to be most

interesting. Repeating the present study, with simultaneous sampling at

the three sites with replicate tows (or individual station occupations

over a short time period of one to two weeks) might help to clarify

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 98

spatial distributions. Nevertheless, the feasibility of funding for

simultaneous and/or replicate sampling must be questioned due to the

high cost of shiptime. A final area that needs more consideration is

complete descriptions of life stages from hatching until juvenile form

is reached. Uca spp. is especially attractive for species differentia

tions, as fiddler crabs occupy important ecological positions world

wide. Lumping at the generic level can lead to misconceptions in inter

pretation of data.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Summary and Conclusions

1. Larval dispersal and postlarval recruitment are vital processes for

the maintenance of ecologically and economically significant species of

decapod crustaceans. Vertical distribution in the water column has an

extremely important effect on the particular retention or expulsion/im-

migration mechanisms employed by various developmental stages.

2. Only 14 known studies have been conducted concerning vertical dis

tribution of decapod larvae and postlarvae, in addition to the present

one. In 50% of the previous studies, sampling was not extended past a

24-hour period; 57% examined only one species; 43% did not differentiate

among stages of development, and 71% did not sample from surface to

bottom. The only extensive study (Cronin, 1979) was done with

Rhithropanopeus harrisii, a low salinity, estuarine crab which cannot be

considered characteristic of all decapods.

3. The objectives of the present study were to investigate variations

in vertical distribution according to temporal (diurnal), spatial (estu

arine, transitional, oceanic), ontogenetic (larval stages, postlarvae),

and environmental factors (especially light, temperature, salinity and

tides); and to relate the effects of vertical positioning to dispersal-

recruitment strategies.

4. Three stations were established for the present study: York River

mouth (estuarine) (37°12'N, 76°16*W); Chesapeake Bay mouth (transition

al) (36°58'N, 76°07’W); Chesapeake light tower (offshore) (35°54’N, 75°

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 100

43*W). Each station was occupied for a continuous 72 hour period in

late summer, and quantitative plankton samples were taken every three

hours from neuston (0.10-0.15 m), 1 m, 3 m, 6 m, epibenthic (10.7-12.8

m) depths. The total collection consisted of 375 samples (125 from each

station).

5. A total of 41 species, 160 developmental stages and an estimated

6,000,000 specimens were collected. Percent of total catch by station

was York River mouth (7%), Chesapeake Bay mouth (7%), offshore (86%).

True crabs (Brachyura) accounted for 53% of the species, 50% of the

stages and 92.42% of the total catch. Anomurans, thalassinideans and

shrimps made up 2.16, 1.24 and 0.18% of the total catch, respectively.

6. Callinectes sapidus Rathbun constituted 87.40% of the total collec

tion followed by Uca spp. (3.45%), Pinnixa chaetopterana Stimpson

(1.74%), Hexapanopeus angustifrons (Benedict and Rathbun) (1.42%),

Pagurus annulipes (Stimpson) (1.32%), and Upogebia affinis (Say)(1.08%).

7. Of the 160 developmental stages, 56 were found in sufficient quanti

ties for analysis. Zoeae I, II, and III of Callinectes sapidus were the

most common stages at 54.72, 26.05, and 5.01% of total catch, respec

tively (85.78% together). Zoea II and the postlarva of Uca spp. were

next at 1.46 and 0.96%, respectively.

8. Fifteen significantly different distribution groups were established

based on comparisons of Spearman rank correlation coefficients at the

five depths sampled.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 101

9. Day-night weighted mean depth calculations for each group were exam

ined for significance using the Mann-Whitney test. Kruskal-Wallis

single factor analysis of variance by ranks was employed to investigate

effects of environmental parameters on vertical distribution. The pos

sibility of diurnal vertical migration was tested using time series

analysis (auto- and cross-correlation).

10. Spatial proximity to the estuary greatly affects vertical position

ing. Overall day-night mean depths for collective larvae and postlarvae

(and the Mann-Whitney significance level) were: York River mouth, 5.96-

4.24 m (p = 0.10); Chesapeake Bay mouth, 7.49-3.19 m (p < 0.001);

offshore, 1.86-1.41 m (p > 0.20).

11. Light was proposed to be the major factor affecting distribution,

with little effect from temperature, salinity, tidal cycles, wind speed

and direction, cloud cover and sea state. Diurnal vertical migration

was documented for certain forms.

12. Six dispersal-recruitment patterns were established for collected

genera based on vertical and spatial distributions of larvae and post

larvae and adult habitats: retained estuarine (Neopanope, Palaemonetes,

and Panopeus, with Alpheus. Eurypanopeus. Ogyrides. Polyonyx and Sesarma

tentatively included due to low abundances), retained estuarine-transi-

tional (Callianassa. Pinnixa. Pinnotheres, and Upogebia, with Crangon.

Hippolyte. and Rhithropanopeus included tentatively), retained transi

tional-nearshore (Euceramus. Hexapanopeus. and Pagurus. with

Trachypenaeus as speculative), retained offshore (Emerita. Libinia, and

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 102

Ovalipes, with Cancer. Naushonia, and Ocypode as tentative), expelled

with estuarine spawning (Uca), expelled with transitional spawning

(Callinectes. with Penaeus. and Xiphopenaeus in low numbers).

13. Hypothesized dispersal-recruitment mechanisms consisted of main

tenance at a given upper, mid or lower depth without diurnal vertical

migration; active vertical migration to the depth of zero net motion;

and varying degrees of vertical migration throughout the water column.

14. The present study was longer than 79% of the known previous stud

ies, with 26 more species (273%) and 96 more stages (250%) differen

tiated than in any other investigation. Large numbers of specimens

collected add strength to interpretations of results.

15. The phenomenon of diurnal vertical migration is extremely complex

with numerous interacting environmental and behavioral factors. None

theless, vertical positioning is one of the most important influences on

dispersal-recruitment mechanisms.

16. Specimens of Xiphopenaeus kroyeri (Heller) were collected from

Virginian waters for the first time. A range extension of about 190 km

northward from Cape Hatteras was provided (Maris, in press). The possi

bility of breeding stocks existing near the Chesapeake Bay was

discussed.

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Previous Studies of Vertical Distribution and Recruitment.

161

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Table A-l. Extensive experimental studies of vertical migration.

Birge (1895) Vinogradov (1954) Parker (1902) Cushing (1955) Juday (1903) Harris and Wolfe (1955) Esterly (1912, 1914, 1919) Marshall and Orr (1955) Michael (1911) Manteifel (1959a,b, 1960) Dice (1914) Vinogradov (1959) Rose (1925) Siebeck (1960) Russell (1925, 1926a,b,c, Ringelberg (1961, 1964) 1927a, 1928a,b,c, McLaren (1963) 1930, 1931a,b, 1934) Verwey (1966b) Southern and Gardiner (1926, Segal (1970) 1932) Grindley (1972) Kikuchi (1927, 1930a, 1937, Motoda (1972) 1938) Roe (1974) Nikitine (1929) Menshutkin and Rudyakov (1975) Worthington (1931) Forward (1976b) Clarke (1933) Moreira (1976) Nicholls (1933) Angel (1984) Worthington and Ricardo (1936) Domanski (1984) Langford (1938) Pugh (1984) Ullyott (1939) Roe (1984a,b) Pennak (1944) Roe et al. (1984a,b) Hardy and Paton (1947) Roe and Badcock (1984) Hardy and Bainbridge (1954)

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Table A-2. Factors important for vertical migration.

LIGHT - INTENSITY AND WAVELENGTH

Groom and Loeb (1890) Segal (1970) Loeb (1893a,b, 1906, 1907, Crisp and Ghobashy (1971) 1908, 1911) Lincoln (1971) Bauer (1909) Sulkin (1973, 1975) Ewald (1910, 1912) Forward (1974, 1976a, 1977) Franz (1910, 1911, 1912, 1913) Forward and Costlow (1974) McGinnis (1911) Forward and Cronin (1979, 1980) Mast (1917, 1921) Buikema (1975) Fox (1925) Ennis (1975a) Clarke (1933) Via and Forward (1975) Spooner (1933) Ott and Forward (1976) Kikuchi (1938) Bentley and Sulkin (1977) Clarke and Backus (1956, 1964) Latz and Forward (1977) Siebeck (1960) Bardolph and Stavn (1978) Bayne (1964) Bigford (1979) Ringelberg (1964) Burton (1979) Boden and Kampa (1967) Alldredge and King (1980) Ringelberg et al. (1967) Cronin and Forward (1980) Itoh and Hanaoka (1968) Meyers (1980) Blaxter (1970) Jacoby (1982) Itoh (1970) Roe (1983) Forward et al. (1984)

SPECIFIC GRAVITY

Eyden (1923)

GRAVITY

Parker (1902) Forward (1976a) McGinnis (1911) Ott and Forward (1976) Kanda (1918) Latz and Forward (1977) Kikuchi (1938) Bigford (1979) Bayne (1964) Jacoby (1982) Crisp and Ghobashy (1971) Pires and Woollacott (1983) Sulkin (1973, 1975)

PRESSURE

Hardy and Bainbridge (1951) Ennis (1973, 1975a) Knight-Jones and Qasim Naylor and Isaac (1973) (1955, 1967) Sulkin (1973) Rice (1961, 1962, 1964, 1967) Bentley and Sulkin (1977) Bayne (1963) Wheeler and Epifanio (1978) Knight-Jones and Morgan (1966) Burton (1979) Lincoln (1970, 1971) Jacoby (1982)

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Table A-2. continued.

TEMPERATURE

McGinnis (1911) Ratte (1979) Schroder (1962) Madhupratap et al. (1981) Angel (1968) Pingree et al. (1982) McLaren (1974) McConnaughey and Sulkin (1984) Kamykowski (1976, 1981) Williams (1985) Ott and Forward (1976) Williams and Fragopoulu (1985) Harbison and Campenot (1979)

SALINITY

Hansen (1951) Scarratt and Raine (1967) Harder (1957, 1968) Roberts (1971) Lance (1962) Latz and Forward (1977) Grindley (1964) Rosenberg and Costlow (1979)

OXYGEN

LaRow (1970) Meyers (1980) Wilson (1972)

CHEMICALS - pH

Bayly (1963) Connell (1978)

PHYSIOLOGICAL RHYTHM

Harris (1963) Cronin and Forward (1979, 1983) Allen (1966, 1972) DeCoursey (1979, 1980, 1981) Enright and Hamner (1967) Moller and Branford (1979) LaRow (1968, 1969) Sulkin et al. (1979) Forward and Davenport (1970) Bergin (1981) Ennis (1975b) Christy (1982) Richter (1973) Forward et al. (1982) Saigusa (1976, 1981) Saigusa (1982) Saigusa and Hadaka (1978) Daro (1985) Wheeler (1978) Salmon et al. (1985) Zucker (1978)

PHER0M0NES

Connell (1978)

PHYTOPLANKTON - EXCLUSION

Hardy (1935)

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Table A-2. continued.

FOOD - HUNGER

Bainbridge (1953) Enright and Honegger (1977) Vinogradov (1955) Burton (1979) Petipa (1958, 1964) Pearre (1979) Pearcy (1970) Cronin and Forward (1980) Isaacs et al. (1974) Wright et al. (1980) Zaret and S u f f e m (1976) Huntley and Brooks (1982) Enright (1977b) Williamson and Magnien (1982)

WATER MOVEMENT - CURRENTS, TIDES

Fuks and Meshcheryakova (1959) DeCoursey (1980) Woodmansee (1966b) Forward and Cronin (1980) Alldredge and Hamner (1980) Wroblewski (1982)

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Table A-3. Vertical distribution-migration studies, non-Crustacea.

PHYTOPLANKTON (INCLUDING DINOFLAGELLATES1)

Hasle (1950, 1954) Fischer et al. (1977) Wood and Corcoran (1966) Kamykowski and Zentara (1977) Eppley et al. (1968) Heaney and Furnass (1980) Forward (1976b) Staker and Bruno (1980) Happy-Wood (1976) Heaney and Eppley (1981)

PROTOZOA (EXCLUDING DINOFLAGELLATES)

Fox (1925) Boltovskoy (1973)

COELENTERATA

Russell (1925, 1927a, 1928a, Angel et al. (1982) 1931b) Lie et al. (1983) Verwey (1966b) Mills (1983) Benovic (1973) Arkett (1984) Schmidt (1973) Mills and Vogt (1984) Roe (1974) Pugh (1984) Angel and Baker (1982) Roe et al. (1984b)

CTEN0PH0RA

Angel and Baker (1982) Mills and Vogt (1984) Angel et al. (1982) Roe et al. (1984b)

ROTIFERA

Kikuchi (1927) Magnien and Gilbert (1983) George and Fernando (1970)

ANNELIDA, POLYCHAETA

Russell (1925, 1927a, 1928a, Ohlhorst (1982) 1931b) Wilson (1982) Bhaud (1969) Lie et al. (1983)

MOLLUSCA

Verwey (1966b) Wormuth (1981) Maru et al. (1973) Angel and Baker (1982) Richter (1973) Lie et al. (1983)

ARTHROPODA, INSECTA AND ACARINA

Woodmansee and Grantham (1961) Goldspink and Scott (1971) Teraguchi and Northcote (1966) Swift (1975, 1976) LaRow (1968, 1969, 1970, 1971) Ratte (1979) Chaston (1969) Riessen (1980)

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Table A-3. continued.

ECHENODERMATA

Fox (1925)

CHAETOGNATHA

Michael (1911, 1913) Angel and Baker (1982) Russell (1931a) Angel et al. (1982) Kolosova (1972) Ohlhorst (1982) Pearre (1973) Pierrot-Bults (1982) Roe (1974) Lie et al. (1983) Furuhashi (1976)

UROCHORDATA

Harbison and Campenot (1979) Angel and Baker (1982) Wiebe et al. (1979) Angel et al. (1982) Macquart-Moulin and Patriti Ohlhorst (1982) (1981) Lie et al. (1983)

CHORDATA, PISCES

Russell (1926a,b, 1928c, 1930) Angel et al. (1982) Woodhead and Woodhead (1955) Willis and Pearcy (1982) Ahlstrom (1959) Fortier and Leggett (1983) Konstantinov (1964) Roe (1983) Blaxter and Parrish (1965) Roe and Badcock (1984) Pearcy and Laurs (1966) Kinzer and Schulz (1985) Blaxter (1973) Wurtsbaugh and Li (1985) Angel and Baker (1982) Brewer and Kleppel (1986)

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Table A-4. Vertical distribution-migration studies, Crustacea (excluding decapod larvae).

CLAD0CERA

Dice (1914) Reif and Tappa (1968) Kikuchi (1927) Itoh (1970) Langford (1938) Bosch and Taylor (1973) Harris (1953) Buikema (1975) Cushing (1955) Haney and Hall (1975) Harris and Mason (1956) Macquart-Moulin and Patriti (1981) Siebeck (1960) Lie et al. (1983)

0STRAC0DA

McHardy and Bary (1965) Roe (1974) Angel (1969a) Ohlhorst (1982) Arashkevich (1971) Angel (1984) Rudyakov (1973) Benzie (1984)

COPEPODA

Esterly (1912) Zalkina (1970, 1972) Kikuchi (1927, 1930a) Roe (1972a,b,c,d) Russell (1928b, 1934) Rudyakov and Voronina (1973) Nicholls (1933) McLaren (1974) Clarke (1934a,b,c) Sekiguchi (1975b) Langford (1938) Furuhashi (1976) Bogorov (1941) White et al. (1979) Schallek (1942) Koslow et al. (1981) Farran (1949) Huntley and Brooks (1982) Cushing (1955) Ohlhorst (1982) Marshall and Orr (1960) Williamson and Magnien (1982) Siebeck (1960) Wroblewski (1982) Geinrikh (1961) Lie et al. (1983) Woodmansee and Grantham (1961) Petipa and Ostravskaya (1984) Ummerkutty (1966) Roe (1984b) Itoh and Hanaoka (1968) Williams and Conway (1984) Umminger (1968) Daro (1985) Hure and Scotto di Carlo Williams (1985) (1969, 1974) Itoh (1970)

CIRRIPEDIA

Ohlhorst (1982) Wilson (1982)

PHYLL0CARIDA

Macquart-Moulin and Patriti (1981)

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Table A-4. continued.

STOMATOPODA

Dingle (1968)

MYSIDACEA

Russell (1925, 1927a, 1928a, Morioka and Takahashi (1980) 1931b) Macquart-Moulin and Patriti (1981) Waterman et al. (1939) Angel and Baker (1982) Beeton (1960) Angel et al. (1982) Herman (1963) Ohlhorst (1982) Alldredge and King (1980) Roe (1984a)

CUMACEA

Russell (1925,1927a,1928a,1931b) Macquart-Moulin and Patriti (1981) Corey (1970)

TANAIDACEA

Ohlhorst (1982)

IS0P0DA

Macquart-Moulin and Patriti Ohlhorst (1982) (1981)

AMPHIPODA

Roe (1974) Macquart-Moulin and Patriti (1981) Semenova (1974) Angel et al. (1982) Girisch and Dennert (1975) Ohlhorst (1982) Thurston (1976a,b) Roe et al. (1984b) Shulenberger (1978)

EUPHAUSIACEA

Esterly (1914) Koslow and Ota (1981) Waterman et al. (1939) Angel and Baker (1982) Lacroix (1961) Angel et al. (1982) Brinton (1967) Roe (1983) Alton and Blackburn (1972) Hirota et al. (1984) Roe (1974) Roe et al. (1984b) Youngbluth (1975) Williams and Fragopoulu (1985)

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Table A-4. continued.

DECAPODA, ADULTS

Waterman et al. (1939) Omori and Gluck (1979) Woodmansee (1966a,b) Angel and Baker (1982) Harper (1968) Angel et al. (1982) Aizawa (1969) Roe (1984a) Pearcy (1970, 1972) Bauer (1985) Murillo (1972) Kikuchi and Omori (1985)

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Table A-5. Dispersal-recruitment studies, non-Crustacea.

PORIFERA

Ayling (1980) Keough (1983)

COELENTERATA

Alldredge and Hamner (1980) Hamner and Hauri (1981) Sebens (1981, 1982)

ROTIFERA

Sandlund (1982)

ECT0PR0CTA

Keough (1983)

BRACHI0P0DA

Doherty (1979)

SIPUNCULIDA

Scheltema and Hall (1965)

ANNELIDA, POLYCHAETA

Scheltema (1971c) Oliver and Long (1981) Farke et al. (1979) Hutchings and Murray (1982) Santos and Simon (1980) Keough (1983) Hannan (1981) Hannan (1984) Hutchings (1981)

MOLLUSCA

Redfield (1939) Wood and Hargis (1971) Carriker (1951, 1957, 1961, 1967) Hansen (1980) Pritchard (1952a) Highsmith (1980) Manning and Whaley (1954) Boicourt (1982) Mileikovsky (1960, 1979) Seliger et al. (1982) Scheltema (1966, 1968, 1971a,b,c) Andrews (1983) Haskin (1964) Keough (1983) Robertson (1964) Scheltema and Williams (1983)

ECHINODERMATA

Yamaguchi (1973) Tegner and Dayton (1977)

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Table A-5. continued.

CHAETOGNATHA

Redfield and Beale (1940) Alldredge and Hamner (1980) Rogers (1940) Table 6. continued.

UR0CH0RDATA

Costello and Stancyk (1983)

PROTOCHORDATA

John et al. (1981) Keough (1983)

CHORDATA, PISCES

Rogers (1940) Fortier and Leggett (1982) Hansen and Andersen (1961) Ulanowicz et al. (1982) Graham (1972) Crawford and Carey (1985) Nelson et al. (1977) Runsdorp et al. (1985) Parrish et al. (1981) Shaw et al. (1985) Tanaka (1985)

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Table A-6. Dispersal-recruitment studies, Crustacea.

CLADOCERA

Tonolli (1955) George and Edwards (1976) Sandlund (1982)

COPEPODA

Tonolli (1955) Wooldridge and Erasmus (1980) Jacobs (1968) Burton and Feldman (1982) George and Edwards (1976) Sandlund (1982) Gagnon and Lacroix (1983)

ST0MAT0P0DA

Verwey (1966a) Senta (1967)

CIRRIPEDIA

Rogers (1940) de Wolf (1973, 1974) Bousfield (1955) Strathmann et al. (1981) Barnes (1956) Keough (1983) Connell (1960) Crisp (1985)

MYSIDACEA

Hulburt (1957) Wooldridge and Erasmus (1980)

EUPHAUSIACEA

Wiebe and Flierl (1983)

DECAP0DA, NATANTIA

Fish (1925) Williams (1969) Deevey (1960) Jones et al. (1970) Renfro (I960) Sick (1970) Eldred et al. (1965) Subrahmanyam (1971b) Temple and Fischer (1965) Sandifer (1972, 1973b, 1975) Copeland (1966) Penn (1975) Coepand and Truitt (1966) Goy (1976) Herman et al. (1968) Rochanaburanon and Williamson (1976) Van Engel and Joseph (1968) Young and Carpenter (1977) Munro and Jones (1968) Andryszak (1979) Hughes (1969, 1972) Sandifer and Smith (1979) Makarov (1969) Kennedy and Barber (1981) Rothlisberg et al. (1983)

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Table A-6. continued.

DECAPODA, REPTANTIA, PALINURA - ASTACORA

Johnson (1960, 1971, 1974) Lesser (1978) Ingle et al. (1963) Phillips et al. (1978, 1979) Scarratt (1964, 1968, 1973) Menzies and Kerrigan (1979, 1980) Sims and Ingle (1967) Rimmer and Phillips (1979) Lund and Stewart (1970) Little and Milano (1980) Lyons (1981) Lutjeharms and Heydorn (1981) Ritz (1972) Menzies (1981) Phillips (1975) Richards and Potthoff (1981) Little (1977)

DECAPODA, REPTANTIA, ANOMURA - BRACHYURA

Fish (1925) Sulkin et al. (1979, 1980) Deevey (1960) Smyth (1980) Nichols and Keney (1963) Dittel and Epifanio (1981) Pinschmidt (1963) Provenzano and McConaugha (1981) Hillman (1964) Stuck and Perry (1981) Garth (1967) Johnson (1982) Longhurst (1967) Dittel and Epifanio (1982) Herman et al. (1968) Sulkin and Van Heukelem (1982) Tagatz (1968) Boicourt (1982) Makarov (1969) Christy and Stancyk (1982) Efford (1970) Epifanio and Dittel (1982) Dudley and Judy (1971) Johnson and Gonor (1982) Williams (1971) Kelly et al. (1982) Sage and Herman (1972) Lambert and Epifanio (1982) Sandifer (1972, 1973b,d, 1975) Zeldis and Jillet (1982) Naylor and Isaac (1973) Epifanio et al. (1983) Lucas (1975) McConaugha et al. (1983) Fotheringham and Bagnall (1976) Shanks (1983) Goy (1976) Sulkin et al. (1983) Lough (1976) Epifanio et al. (1984) Oesterling and Evink (1977) Johnson et al. (1984) Andryszak (1979) McConnaughey and Sulkin (1984) Cronin (1979, 1982) Sadler (1984) Cronin and Forward (1979, 1981, Sulkin (1984) 1982) Brookins and Epifanio (1985) Provenzano (1979) Johnson (1985a Sekiguchi (1979) O'Connor and Epifanio (1985) Maris (1980) Shanks (1985)

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Larval and Postlarval Descriptions.

175

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SPECIES DESCRIPTION

Alpheus heterochaelis Knowlton (1973); Sandifer (1972,1973a)

A. normanni Kurata (1970); Sandifer (1972,1973a)

Callianassa atlantica Sandifer (1972,1973a,d)

C. biformis Sandifer (1972,1973a,d)

Callinectes sapidus Costlow et al. (1959); Costlow and Bookhout (1959); Costlow (1965); Kurata (1970); Sandifer (1972,1973a)

Cancer (Metacarcinus) Sastry (1977a) borealis

C. (Cancer) Sandifer (1972,1973a); Sastry (1977b) irroratus

Crangon septemspinosa Tesmer and Broad (1964); Sandifer (1972,1973a)

Emerita talpoida Rees (1959); Kurata (1970); Sandifer (1972, 1973a)

Euceramus praelongus Roberts (1968); Sandifer (1972,1973a); Maris (1983)

Eurypanopeus depressus Hyman (1925); Costlow and Bookhout (1961a); Kurata (1970); Sandifer (1972,1973a); Martin (1984)

Hexapanopeus Hyman (1925); Costlow and Bookhout (1966a); angustifrons Kurata (1970); Sandifer (1972,1973a); Martin (1984)

Hippolyte pleuracanthus Sandifer (1972,1973a); Shield (1978)

Libinia spp. Kurata (1970); Sandifer and Van Engel (1971); Sandifer (1972,1973a); Johns and Lang (1977)

Naushonia crangonoides Sandifer (1972,1973a); Goy and Provenzano (1978)

Neopanope sayi Hyman (1925); Chamberlain (1961); McMahan (1967); Sandifer (1972,1973a); Kurata (1970); Martin (1984)

Ocypode quadrata Kurata (1970); Diaz and Costlow (1972); Sandifer (1972,1973a)

Ogyrides alphaerostris Sandifer (1972,1973a,1974)

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Ovalipes ocellatus Costlow and Bookhout (1966c); Sandifer (1972, 1973a)

Pagurus annulipes Nyblade (1970)

P. longicarpus Roberts (1970); Sandifer (1972,1973a)

jP. pollicaris Nyblade (1970); Sandifer (1972,1973a)

Palaemonetes spp. Broad (1957); Dobkin (1963); Kurata (1970); Sandifer (1973a); Hubschman and Broad (1974)

Panopeus herbstii Hyman (1925); Costlow and Bookhout (1961b); Kurata (1970); Sandifer (1972,1973a); Martin (1984)

Penaeus spp. Cook (1966); Subramanyam (1971a); Sandifer (1973a)

Pinnixa chaetopterana Hyman (1924b); Sandifer (1972,1973a)

P. cylindrica Sandifer (1972,1973a)

P. sayana Hyman (1924b); Sandifer (1972,1973a)

Pinnotheres maculatus Hyman (1924b); Costlow and Bookhout (1966b); Sandifer (1972,1973a)

P. ostreum Hyman (1924b); Sandoz and Hopkins (1947); Sandifer (1972,1973a)

Polyonyx gibbesi Gore (1968); Sandifer (1972, 1973a); Maris (1983)

Rhithropanopeus Connolly (1925); Hyman (1925); Chamberlain harrisii (1962); Hood (1962); Kurata (1970); Sandifer (1972,1973a); Martin (1984)

Sesarma (Chiromantes) Hyman (1924a); Costlow and Bookhout (1960); cinereum Kurata (1970); Sandifer (1972,1973a)

S_. (Sesarma) Hyman (1924a); Costlow and Bookhout (1962); reticulatum Sandifer (1972,1973a)

Trachypenaeus Cook (1966); Kurata (1970); Sandifer (1972, constrictus 1973a)

Uca spp. Hyman (1920); Kurata (1970); Sandifer (1972, 1973a)

Upogebia affinis Kurata (1970); Sandifer (1972,1973a,c)

Xiphopenaeus kroyeri Kurata (1970)

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX C

Results of Statistical Tests

Key

Significance Level (p)

_£ code <0.05 * < 0.01 * * <0.001 ***

X = not sampled = no specimens obtained

Tides Wind Direction

1 = slack before flood 1 = N 2 = maximum flood 2 = NE 3 = slack before ebb 3 = E 4 = maximum ebb 4 = SE 5 = S Light 6 = SW 7 = W 1 = day 8 = NW 2 = night

178

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Critical Values of Kruskal-Wallis H Distribution (Zar, 1974). (N = sample size; DF = degrees of freedom)

H H N = 5 N = 4 DF = 4 P DF = 3

0.091 0.999 0.024 0.207 0.995 0.072 0.297 0.990 0.115 0.484 0.975 0.216 0.711 0.950 0.352 1.064 0.900 0.584 1.923 0.750 1.213 3.357 0.500 2.366 5.385 0.250 4.108 7.779 0.100 6.251 9.488 0.050 7.815 11.143 0.025 9.348 13.277 0.010 11.345 14.860 0.005 12.838 18.467 0.001 16.266

Critical Values of Spearman Critical Values of Mann-Whitney Rank Correlation Coefficient U Distribution (Zar, 1974) (Zar, 1974)

N = 25 N = 13/12 two-tailed two-tailed r P U P

0.142 0.50 103 0.20 0.265 0.20 109 0.10 0.337 0.10 115 0.05 0.398 0.05 121 0.02 0.466 0.02 125 0.01 0.511 0.01 129 0.005 0.551 0.005 133 0.002 0.598 0.002 136 0.001 0.630 0.001

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Table C-l. Spearman rank correlation coefficients (rs) for collective larvae and postlarvae distribution with depth and time among the three stations; N = 25.

depth (m) bay offshore

0 +0.786*** +0.249 1 +0.468* -0.197 3 +0.241 -0.110 6 +0.211 +0.098 11 -0.109 +0.193

0 +0.584** 1 +0.143 3 -0.120 6 -0.019 11 -0.339

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Table C-2. Kruskal-Wallis single factor analysis of variance by ranks test statistics (H) for collective larvae and postlarvae distribution with depth, light and tidal cycles at each station; N = 5 (N = 4 for total-tides, day-tides, night- tides).

York bay offshore

Total-Depth 16.251** 23.516*** 70.016***

Depth-Day 28.563*** 39.004*** 34.298***

Depth-Night 22.538*** 26.874*** 39.653***

Total-Tide 1 4.357 13.823** X

Total-Tide 2 1.256 6.814 X

Total-Tide 3 5.197 7.904 X

Total-Tide 4 15.635** 1.981 X

Day-Tide 1 9.708* 11.758* X

Day-Tide 2 5.650 10.233* X

Day-Tide 3 4.625 10.025* X

Day-Tide 4 14.896** 10.996* X

Night-Tide 1 3.592 10.008* X

Night-Tide 2 7.733 5.018 X - Night-Tide 3 10.542* 7.300 X

Night-Tide 4 9.292 6.904 X

Total-Tides 5.386 2.869 X

Day-Tides 0.951 1.700 X

Night-Tides 5.768 3.676 X

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Table C-3. Mean number per cubic meter of collective larvae and post larvae with time and depth, with Mann-Whitney test results; standard deviation in parentheses.

Depth (m) 0 1 3 6 11/13

York River Mouth

mean day 2.71 40.18 27.38 16.35 34.36 (5.53) (99.47) (24.82) (10.30) (24.71)

mean night 161.74 22.71 12.38 20.79 49.91 (215.83) (38.97) (6.10) (24.88) (39.33)

U 153*** 79 122*** 84 102

Chesapeake Bay Mouth

mean day 8.22 10.42 24.47 82.70 135.46 (26.55) (13.49) (29.27) (82.44) (150.64)

mean night 187.21 21.00 27.18 27.32 65.53 (147.93) (19.14) (18.78) (24.75) (64.64)

U 152*** 121* 100 123* 101

Offshore

mean day 813.90 601.83 512.39 160.27 15.13 (1475.37) (401.35) (443.89) (274.01) (10.16)

mean night 1548.57 2785.37 535.44 48.35 33.79 (1620.25) (6734.66) (462.22) (63.79)' (20.95)

U 116* 98 80 87 125**

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Table C-4. Percent of total catch with light and tides for collective larvae and postlarvae per station with Kruskal-Wallis test results, N = 4; and Mann-Whitney test results, N = 13/12.

Slack Slack before Max before Max Station Light Flood Flood Ebb Ebb H total U

York day 21 18 41 20 1.181 33 117* night 22 39 28 11 4.385 67

total 22 32 32 14 3.857 100

bay day 14 27 45 14 5.560 45 96 night 21 13 24 42 1.064 55

total 18 19 33 30 5.549 100

ocean day XXXXX 32 109 night XXXXX 6 8

total XXXXX 100

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Table C-6. Kruskal-Wallis single factor analysis of variance by ranks test statistic (H) for group distributions with depth, light and tidal cycles; significance levels, 9.488*, 13.277**, 18.467*** , N = 5.

Total- Depth- Depth- Total- Total- Total- Total- »roup Depth Day Night Tide 1 Tide 2 Tide 3 Tide 4

1 2.214 5.762 8.228 1.569 6.498 2.974 9.948 2 3.829 5.909 16.692 0.242 6.668 3.380 1.725 3 45.031 31.432 19.638 12.276 9.429 14.774 14.430 4 0.432 9.603 6.433 1.144 3.308 5.187 2.868 5 19.952 13.510 33.940 3.704 3.393 6.697 9.686 6 1.888 10.808 23.032 2.940 5.557 9.088 1.515 7 3.079 12.677 21.420 1.199 5.162 4.366 0.456 8 17.538 39.610 14.159 11.105 4.370 5.187 2.868 9 25.513 30.668 1.378 12.847 7.089 3.509 2.868 10 14.171 12.817 3.509 5.406 2.460 5.755 11 55.983 21.049 39.407 XX XX 12 280.626 40.135 42.244 XX XX 13 5.641 6.405 0.720 XX XX 14 10.488 5.885 0.778 XX XX 15 12.736 17.235 5.196 XX X X

Day Day Day Day Night Night Night Night Group Tide-1 Tide-2 Tide-3 Tide-4 Tide-1 Tide-2 Tide-3 Tide-4

1 3.617 4.158 2.825 5.904 6.042 8.658 2.825 3.633 2 2.525 2.083 1.967 5.232 5.225 9.092 6.908 2.625 3 6.750 10.050 8.633 9.371 6.908 4.458 9.825 6.725 4 3.167 6.208 4.608 7.543 2.650 2.727 5.567 3.954 5 1.358 8.358 1.158 7.271 2.858 3.927 2.725 4.636 6 3.500 7.650 7.433 5.043 8.100 4.882 6.900 8.268 7 4.833 9.708 1.033 3.993 7.890 3.164 8.800 4.804 8 11.100 9.300 11.025 11.586 7.700 5.019 6.433 4.357 9 7.383 7.100 10.558 7.404 5.867 4.036 3.225 0.693 10 4.758 3.225 5.133 2.839 4.658 4.745 0.167 2.839 11 XXX X X XXX 12 XXX XX XX X 13 XXX X X X XX 14 XXX X X XX X 15 X X X X X XX X

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Table C-7. Mann-Whitney test results. Groups, day-night distribution with depth.

Depth (m) Group 0 1 3 6 11/13

1 132.5** 97 88 90 79

2 142*** 91 92 92 109.5

3 135** 117* 87 99 83.5

4 143*** 99 88 97 79

5 154*** 86 90 98 100

6 155*** 111 92 87 103

7 156*** 136.5*** 142*** 131.5** 145***

8 156*** 93 109 122* 87

9 123.5* 123.5* 99 120* 100

10 86 98 79 80 87

11 112 96 78 85 85

12 121* 89 79 93 119*

13 101 89 89 84.5 78

14 82.5 84 78 83.5 123.5*

15 119* 117* 86 107 109.5

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Table C-8. Percent of total catch with light and tides for groups, with Kruswall-Wallis test results, N = 4; and Mann-Whitney test results, N = 13/12.

Slack Slack before Max before Max Group Light Flood Flood Ebb Ebb H Total U

1 day 22 18 52 8 2.104 20 104 night 19 43 36 2 5.359 80 total 20 38 39 3 8.276 100

2 day 20 12 56 12 2.324 23 98 night 15 73 11 1 6.692 77 total 16 59 21 4 8.184 100

3 day 11 30 38 21 3.643 37 102 night 32 26 16 26 1.974 63 total 24 28 24 24 2.227 100

4 day 9 20 45 26 1.319 36 97 night 8 13 49 30 2.513 64 total 8 16 47 29 3.748 100

5 day 12 42 11 34 7.429 19 125** night 37 6 10 47 2.596 81 total 32 13 10 45 3.766 100

6 day 18 43 18 21 6.632 29 109 night 35 17 18 40 1.782 71 total 27 24 18 31 0.935 100

7 day 6 52 24 29 7.407 3 156*** night 14 16 23 47 1.160 97 total 14 17 23 46 1.525 100

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Table C-8. continued.

8 day 22 23 36 19 3.363 46 88 night 24 18 20 38 1.821 54 total 23 20 27 30 1.083 100

9 day 34 26 24 16 1.577 63 91 night 45 12 20 23 4.038 37 total 38 21 23 18 2.855 100

10 day 61 16 14 9 0.901 60 90.5 night 22 31 24 23 0.276 40 total 45 22 18 15 1.380 100

11 day X X X X X 35 94 night X X X X X 65 total XX X X X 100

12 day XX XX X 21 103 night XX XX X 79 total X X X X X 100

13 day X X X XX 74 99.5 night XX X XX 26 total XX X X X 100

14 day X X XX X 42 97 night XX XX X 58 total XX X XX 100

15 day XX XX X 32 109 night XX X X X 68 total XX X X X 100

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 189

Table C-9. Weighted mean depth of groups with time; standard deviation in parentheses; Mann-Whitney test statistic = U.

Group 1 2 3 4 5

mean day 4.08 4.34 9.71 4.58 5.75 (2.40) (2.63) (1.52) (2.36) (2.69)

mean night 2.67 1.96 7.62 3.19 1.31 (3.27) (2.33) (2.89) (2.67) (1.93)

U 109 112* 116* 106 146***

U table 115 107 115 115 115

significance (p=0.10) (p<0.05) (p<0.05) (p>0.10) (p<0.001)

Group 6 7 8 9 10

mean day 6.63 8.12 6.59 7.42 7.01 (2.71) (4.16) (2.02) (1.42) (2.68)

mean night 1.87 3.38 3.37 4.53 5.70 (1.75) (3.10) (1.74) (3.11) (3.62)

U 132*** 114* 121* 86

U table 107 107 115 115 99

significance (p<0.001) (p<0.02) (p<0.001) (p=0.02) (p>0.20)

Group 11 12 13 14 15

mean day 2.11 1.66 0.85 1.17 6.74 (1.15) (0.80) (1.06) (2.26) (3.07)

mean night 1.11 1.02 2.19 8.58 6.64 (0.42) (0.39) (2.40) (5.19) (4.15)

U 117* 117.5* 12.5 7* 84.5

U table 115 115 34 46 115

significance (p<0.05) (p<0.05) (p>0.20) (p=0.02) (p>0.20)

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Table C-10. Spearman rank correlation coefficients (rs ) for group distri bution with environmental parameters and depth; N = 25.

Group Depth Light Temp. Sal. Wind Wind Cloud Sea St. (m) Dir. Sp.

1 0 +0.690 +0.040 -0.024 +0.162 -0.085 -0.038 -0.168 1 +0.023 -0.167 -0.110 +0.191 +0.159 -0.162 +0.056 3 +0.119 -0.382 -0.243 +0.075 +0.176 +0.100 +0.274 6 +0.166 -0.143 -0.420 -0.077 +0.091 +0.138 +0.161 11 +0.101 -0.071 +0.471 +0.313 +0.513 +0.444 +0.359

2 0 +0.812 -0.122 -0.058 +0.145 -0.113 -0.109 -0.189 1 +0.071 +0.238 -0.045 +0J.07 +0.079 +0.032 +0.099 3 +0.090 -0.172 -0.218 +0.207 +0.145 +0.055 +0.411 6 +0.278 +0.148 -0.076 +0.082 +0.206 +0.109 +0.389 11 -0.050 +0.228 +0.115 +0.345 +0.128 +0.128 +0.163

3 0 +0.749 +0.112 +0.141 +0.307 +0.179 +0.152 +0.074 1 +0.671 +0.219 +0.448 +0.253 +0.590 +0.183 +0.526 3 +0.215 +0.365 +0.171 +0.268 +0.194 +0.266 +0.352 6 +0.376 +0.087 -0.145 +0.082 +0.009 -0.308 +0.067 11 +0.173 -0.022 +0.110 +0.287 -0.088 -0.048 +0.214

4 0 +0.752 -0.442 +0.325 +0.183 +0.118 -0.250 -0.112 1 +0.329 -0.191 -0.030 +0.258 -0.179 -0.157 -0.344 3 +0.223 -0.164 +0.298 +0.282 +0.021 -0.012 -0.162 6 -0.054 +0.168 +0.025 +0.119 -0.014 -0.265 -0.038 11 +0.138 -0.028 +0.237 -0.165 +0.153 -0.405 +0.308

5 0 +0.898 -0.722 +0.172 +0.298 +0.217 +0.315 +0.133 1 +0.818 -0.332 +0.098 +0.356 -0.050 +0.243 +0.096 3 +0.828 -0.409 +0.218 +0.273 +0.295 +0.306 +0.043 6 +0.671 -0.162 -0.125 +0.093 +0.073 +0.083 +0.110 11 +0.771 -0.274 +0.185 +0.425 -0.137 -0.193 -0.414

6 0 +0.911 -0.391 +0.135 +0.277 +0.023 -0.085 -0.023 1 +0.059 +0.084 -0.222 +0.040 -0.504 -0.083 -0.352 3 +0.263 -0.084 +0.093 +0.195 -0.497 +0.100 -0.308 6 -0.036 +0.463 -0.058 +0.214 +0.102 +0.078 +0.186 11 +0.021 +0.132 +0.148 +0.013 -0.014 -0.092 +0.107

7 0 +0.908 -0.448 +0.156 +0.284 +0.044 -0.015 -0.021 1 -0.150 +0.144 -0.153 -0.021 -0.149 +0.135 +0.018 3 +0.283 -0.051 +0.078 +0.157 -0.007 +0.268 +0.046 6 +0.062 +0.388 +0.013 +0.070 -0.071 +0.032 +0.076 11 -0.092 +0.211 +0.331 -0.231 -0.452 -0.431 -0.425

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 191 Table C-10. continued.

8 0 +0.917 -0.472 -0.254 +0.254 +0.093 +0.146 +0.069 1 +0.270 -0.311 -0.096 +0.019 -0.154 -0.015 +0.026 3 +0.423 -0.494 +0.263 +0.320 +0.013 +0.177 -0.151 6 -0.298 +0.250 +0.063 -0.168 +0.199 -0.287 +0.238 11 +0.038 +0.078 -0.032 -0.427 +0.184 -0.421 +0.178

9 0 +0.749 -0.233 +0.330 +0.350 +0.361 +0.516 +0.376 1 +0.749 -0.253 +0.252 +0.324 +0.173 +0.395 +0.291 3 +0.343 -0.019 +0.092 +0.163 -0.222 +0.106 -0.123 6 -0.275 +0.395 -0.135 +0.362 +0.071 -0.058 +0.427 11 -0.076 -0.032 +0.119 -0.140 +0.156 -0.023 +0.187

10 0 +0.543 +0.203 +0.464 +0.469 +0.285 +0.480 +0.306 1 +0.573 -0.020 +0.391 +0.196 +0.273 +0.337 +0.306 3 +0.190 -0.053 +0.128 +0.141 -0.349 -0.060 -0.204 6 -0.275 +0.395 -0.135 +0.362 +0.071 -0.058 +0.427 11 +0.146 +0.405 +0.099 -0.245 +0.127 -0.083 +0.119

11 0 +0.453 +0.273 -0.072 +0.063 -0.024 X -0.119 1 +0.308 +0.483 +0.483 +0.228 -0.169 X -0.184 3 +0.130 +0.575 +0.575 +0.289 +0.117 X +0.217 6 +0.046 +0.287 +0.348 +0.747 -0.124 X -0.011 13 +0.080 -0.092 -0.104 +0.350 -0.396 X -0.340

12 0 +0.539 +0.153 +0.139 -0.079 -0.055 X -0.044 1 +0.236 +0.463 +0.463 +0.033 -0.253 X -0.021 3 +0.116 +0.323 +0.323 -0.016 +0.038 X +0.164 6 -0.016 +0.247 +0.297 +0.543 -0.270 X +0.040 13 +0.572 +0.076 +0.069 +0.122 -0.015 X +0.306

13 0 +0.071 -0.050 +0.645 -0.071 +0.086 X +0.261 1 +0.316 +0.137 +0.137 +0.260 +0.278 X +0.404 3 +0.230 -0.023 -0.023 +0.064 +0.273 X +0.320 6 +0.630 +0.438 +0.438 +0.602 +0.563 X +0.574 13 +0.625 +0.500 +0.500 +0.598 +0.505 X +0.550

14 0 +0.163 -0.168 +0.448 -0.079 +0.174 X +0.238 1 +0.510 +0.529 +0.529 +0.535 +0.481 X +0.507 3 +0.625 +0.500 +0.500 +0.598 +0.505 X +0.550 6 +0.408 +0.397 +0.388 +0.501 +0.407 X +0.351 13 +0.749 +0.183 +0.183 -0.115 +0.220 X +0.246

15 0 +0.677 -0.073 +0.542 -0.211 +0.160 X +0.227 1 +0.578 +0.158 -0.158 -0.301 -0.014 X -0.014 3 +0.268 +0.215 +0.215 -0.109 +0.169 X +0.226 6 -0.102 +0.469 +0.454 +0.332 +0.052 X +0.253 13 +0.412 -0.496 -0.498 +0.061 +0.493 X +0.498

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure C-l. Time series analysis, autocorrelation coefficients for light with cross-correlation coefficients for light-collec tive weighted mean depth per station.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. r

LIGHT A. YORK RIVER MOUTH

r LAG(k)

LIGHT B. CHESAPEAKE BAY MOUTH

r LAG(k)

LIGHT C. OFFSHORE

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Figure C-2. Weighted mean depth of group distributions with time per station. A-C = York River mouth; D-J = Chesapeake Bay mouth; K-0 = Offshore.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 193

TIME (HR) TIME (HR) 0900 1200 1500 1800 2100 0000 0300 0600 0900 1200 1500 1800 2100 0000 0300 0600 0 1 1 1 •;■"svsr -tw-., V- gji 1 2

CL LU □ 5 < •y sr>’^ lvt£'*£r;*V (4.08) tu 6 a LU 7 i- X o 8 LU 5 9 DAY 10

11 A. GROUP 1. YORK RIVER MOUTH B. GROUP 2. YORK RIVER MOUTH uca spp. n u c a spp. in

TIME (HR) TIME (HR) 0900 1200 1500 1800 2100 00000300 0600 0900 1200 1500 1800 2100 0000 0300 0600 T T

(9.71)

4.58

11 to /•.“ • ■ > & !« GROUP 3. YORK RIVER MOUTH D. GROUP 4. CHESAPEAKE BAY PINNIXA CHAETOPTERANA II MOUTH CALLINECTES SAPIDUS I

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 194

TIME (HR) TIME (HR) 09001200 1S00 1800 2100 0000 0300 0600 0900 1200 1500 1800 2100 0000 0300 0600 0 1 1 1— 1 2 £ (6.63) X 3 K 0. LU □ Z 5 < • V s* Ss ' • ■'•“V: LU X 6 Q (5.75) LU 7 V- X o 8 LU 9 DAY 10

11 E. GROUP 5. CHESAPEAKE F. GROUP 6. CHESAPEAKE BAY MOUTH BAY MOUTH UCA spp. n UCA spp. HI

TIME (HR) TIME (HR) 0900 1200 1500 1800 2100 0000 0300 0600 0900 1200 1500 1800 2100 0000 0300 0600 0 > 1 1—

1 2

X i- 3 Q. UJ 4 a z 5 < (6.59) LU X 6 a LU 7 i- iiMSiBi X o 8 LU 9 DAY 10

11 G. GROUP 7. CHESAPEAKE H. GROUP 8. CHESAPEAKE BAY MOUTH BAY MOUTH UCA spp. PL HEXAPANOPEUS ANGUSTIFRONS I

. RU 1. OFFSHORE 11. GROUP K. WEIGHTED MEAN DEPTH (m) _ WEIGHTED MEAN DEPTH Im) ALNCE SPDS I SAPIDUS CALLINECTES UEAU PALNU I PRAELONGUS EUCERAMUS RU 9 CHESAPEAKE 9. GROUP 0 0900 0900 1200 1500 1800 2100 0000 0300 0600 0300 0000 2100 1800 1500 1200 0900

1200

1500 IE (HR) TIME A MOUTH BAY IE (HR) TIME

1800

2100

0000

0300

0600

5 HI X I- HI □ Hi Q. i- x O Q X Ui < L. 10 ALNCE SPDS II SAPIDUS CALLINECTES OFFSHORE 12. GROUP 11 UEAU PALNU II PRAELONGUS EUCERAMUS RU 1. CHESAPEAKE 10. GROUP 1 1 1 1 0 1 3 2 7 8 9 6 5 4 0900 0900

1200 1200 1 I DAY ( 1

1500 1500 . 66 --- IE IHR) TIME IE (HR) TIME

A MOUTH BAY

) 1800 1300

a 2100 2100 -*V;. ■ '

0000 0000

0300 0300

195

0600 0600

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced

WEIGHTED MEAN DEPTH (ml 0900 1200 1500 1800 2100 0000 0600 0300 0600 0000 2100 1800 1500 1200 0900 RU 1. OFFSHORE 14. GROUP ALNCE SPDS PL SAPIDUS CALLINECTES IE (HR) TIME iaW«aSS>25SS*3>!&Sa!' /«Kfe 'jLi V r-c^ J £ ui ui CL CD a Ui < Ui I— X a M. ALNCE SPDS Y SAPIDUS CALLINECTES RU 1. OFFSHORE 13. GROUP 0900

*35ga> S2S?.v?

1200 0.85

1500 IE (HR) TIME

1800 _E Ui X h— Ui a X Ui Z X CD < a Ui X f-

2100 . RU 1. OFFSHORE 15. GROUP 0.

0000 90 20 50 8020 00 30 0600 0300 0000 2100 1800 1500 1200 0900 AUU ANLPS I ANNULIPES PAGURUS

0300 (6.74)

0600 IE (HR) TIME

196 Figure C-3. Time series analysis, autocorrelation coefficients for light with cross-correlation coefficients for light-group mean depth per station. A-C = York River mouth; D-J = Chesapeake Bay mouth; K-0 = offshore.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 197

LIGHT

A. GROUP 1. YORK

u c a spp. n

LIGHT

B. GROUP 2. YORK

u c a spp. nr

r LAG(k)

LIGHT C. GROUP 3. YORK PINNIXA CHAETOPTERANA II

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 198

r LAG(k)

- 1 1 LIGHT D. GROUP A. BAY CALLINECTES SAP1DUS I

r ,2-

LIGHT

E. GROUP 5. BAY uca spp.n

r LAG(k)

LIGHT F. GROUP 6. BAY

u c a spp. Hi

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 199

r r

LIGHT

G. GROUP 7. BAY UCA spp. PL

LIGHT H. GROUP 8. BAY HEXAPANOPEUS ANGUSTIFRONS I

LIGHT I. GROUP 9. BAY EUCERAMUS PRAELONGUS I

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 200

r LAG(k)

«*k

- 1 1 LIGHT J. GROUP 10. BAY EUCERAMUS PRAELONGUS I

r rX y ( k )

K LIGHT

K. GROUP 11. OFF CALLINECTES SAPIDUS I

r * LAGlk)

LIGHT L. GROUP 12. OFF CALLINECTES SAPIDUS II

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 201

r LAG(k)

LIGHT

M. GROUP 13. OFF CALLINECTES SAPIDUS Y

LIGHT

N. GROUP U . OFF CALLINECTES SAPIDUS PL

LIGHT 0. GROUP 15. OFF PAGURUS ANNULIPES I

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX D

Systematic account of species collected. Classification according to Bowman and Abele (1982).

202

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ORDER DECAPODA Latreille, 1803

Suborder Dendrobranchiata Bate, 1888 Superfamily Penaeoidea Rafinesque, 1815 Family Penaeidae Rafinesque, 1815 Penaeus spp. Trachypenaeus constrictus (Stimpson. 1871) Xiphopenaeus kroyeri (Heller, 1862) Suborder Pleocyemata Burkenroad, 1963 Infraorder Caridea Dana, 1852 Superfamily Palaemonoidea Rafinesque, 1815 Family Palaemonidae Rafinesque, 1815 Palaemonetes spp. Superfamily Alpheoidea Rafinesque, 1815 Family Alpheidae Rafinesque, 1815 Alpheus heterochaelis Say, 1818 A. normanni Kingsley, 1878 Family Hippolytidae Dana, 1852 Hippolyte pleuracanthus (Stimpson, 1871) Family Ogyrididae Hay and Shore, 1918 Osyrides alphaerostris (Kingsley. 1880) Superfamily Crangonoidea Haworth, 1825 Family Crangonidae Haworth, 1825 Crangon septemspinosa Say, 1818 Infraorder Thalassinidea Latreille, 1831 Superfamily Thalassinoidea Latreille, 1831 Family Callianassidae Dana, 1852 Callianassa atlantica Rathbun. 1926 C. biformis Biffar, 1971 Family Laomediidae Borradaile, 1903 Naushonia crangonoides Kingsley. 1897 Family Upogebiidae Borradaile, 1903 Upogebia affinis (Say, 1818) Infraorder Anomura H. Milne-Edwards, 1832 Superfamily Paguroidea Latreille, 1803 Family Paguridae Latreille, 1803 Pagurus annulipes (Stimpson, 1860) P. longicarpus Say, 1817 £. pollicaris Say, 1817 Superfamily Galatheoidea Samouelle, 1819 Family Porcellanidae Haworth, 1825 Euceramus praelongus Stimpson. 1860 Polyonyx gibbesi Haig, 1956 Superfamily Hippoidea Latreille, 1825 Family Hippidae Latreille, 1825 Emerita talpoida (Say, 1817) Infraorder Brachyura Latreille, 1803 Section Oxyrhyncha Latreille, 1803 Superfamily Majoidea Samouelle, 1819 Family Majidae Samouelle, 1819 Libinia spp.

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Section Cancridea Latreille, 1803 Superfamily Cancroidea Latreille, 1803 Family Cancridae Latreille, 1803 Cancer (Metacarcinus) borealis Stimpson, 1859 C. (Cancer) irroratus Say, 1817 Section Brachyrhyncha Borradaile, 1907 Superfamily Portunoidea Rafinesque, 1815 Family Portunidae Rafinesque, 1815 Callinectes sapidus Rathbun. 1896 Ovalipes ocellatus (Herbst. 1799) Superfamily Xanthoidea MacLeay, 1838 Family Xaxthidae MacLeay, 1838 Eurypanopeus depressus (Smith, 1869) Hexapanopeus angustifrons (Benedict and Rathbun, 1891) Neopanope sayi (Smith, 1869) Panopeus herbstii H. Milne-Edwards, 1834 Rhithropanopeus harrisii (Gould, 1841) Superfamily Grapsidoidea MacLeay, 1838 Family Grapsidae MacLeay, 1838 Sesarma (Chiromantes) cinereum (Bose [1802]) S. (Sesarma) reticulatum (Say, 1817) Superfamily Pinnotheroidea De Haan, 1833 Family Pinnotheridae De Haan, 1833 Pinnixa chaetopterana Stimpson, 1860 P. cylindrica (Say, 1818) ]?♦ sayana Stimpson, 1860 Pinnixa spp. Pinnotheres maculatus Say. 1818 P. ostreum Say, 1817 - B Superfamily Ocypodoidea Rafinesque, 1815 Family Ocypodidae Rafinesque, 1815 Ocypode quadrata (Fabricius, 1787) Uca spp.

Unknown A — brachyuran postlarva Unknown B - brachyuran postlarva

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX E

Developmental Stage Distributions by Station.

KEY

Species (Stages)

stages = known developmental stages; Z = zoeal stages; PL = postlarva.

Stage (%)

Roman numerals = zoeal stages collected; PL = postlarva; T = total for species; % = % of total for species.

% Distribution

(York River mouth - bay mouth - offshore).

Maximum Density (location)

numbers = number per cubic meter; location = station - depth - light; depth = N - neuston (0.10-0.15 m) EB - epibenthic (11-13 m).

205

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% Maximum density Species (Stages) Stage Distribution (location)

Alpheus heterochaelis I (74) 99- 1- 0 2.238 York-EB-night (5+Z, PL) II (17) 93- 7- 0 0.703 York-EB-night H I (6) 48- 52- 0 0.317 York-6 m-day; Bay-3 m-day V (1) 100- 0- 0 0.109 York-EB-day VI (2) 0-100- 0 0.238 Bay-N-night T (100) 93- 7- 0

Alpheus normanii II (84) 0-100- 0 0.173 Bay-N-day (5+Z, PL) III (16) 0-100- 0 0.032 Bay-N-night T (100) 0-100- 0

Callianassa atlantica I (66) 2- 98- 0 1.359 Bay-EB-day (at least 2Z, PL) II (44) 0-100- 0 2.029 Bay-EB-day T (100) 1- 99- 0

Callianassa biformis I (42) 1- 99- 0 8.156 Bay-EB-day (4Z, PL) II (28) 8- 92- 0 4.907 Bay-EB-day III (15) 24- 76- 0 3.271 Bay-EB-day IV (11) 52- 48- 0 2.486 York-EB-day PL (4) 0-100- 0 1.465 Bay-6 m-night T (100) 12- 88- 0

Callinectes sapidus I (63) <1- 2- 98 11,663.186 Ocean-1 m-night (8Z, PL) II (30) <1- <1-100 11,246.644 Ocean-1 m-night III (6) 0- <1-100 1,064.497 Ocean-1 m-night IV « 1 ) 0- <1-100 65.674 Ocean-N-day V « 1 ) 0- 0-100 16.418 Ocean-N-day VI « D 0- 0-100 32.837 Ocean-N-day VII « 1 ) 0- 0-100 16.418 Ocean-N-day VIII « 1 ) 0- 0-100 5.730 Ocean-1 m-night PL (1) 13- 72- 15 344.909 Bay-N-night T (100) <1- 2- 98

Cancer borealis PL/T (100) 0-100- 0 0.158 Bay-3 m-night (5Z, PL)

Cancer irroratus I (6) 0- 0-100 0.241 Ocean-EB-day (5Z, PL) II (29) 0- 0-100 0.988 Off-EB-day V (26) 0- 0-100 1.137 0ff-6 m-night PL (39) 0- 0-100 1.664 Off-3 m-day T (100) 0- 0-100

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% Maximum density Species (Stages) Stage Distribution (location)

Crangon septemspinosa I (57) 0-100- 0 0.669 Bay-EB-night (7Z, PL) III (5) 100- 0- 0 0.106 York-6 m-day PL (38) 100- 0- 0 0.741 York-EB-night T (100) 43- 57- 0

Emerita talpoida I (24) 0- 26- 74 0.808 Ocean-N-night (6Z, PL) II (31) 0- 4- 96 17.276 Ocean-N-night III (30) 0- 7- 93 46.282 Ocean-1 m-night IV (10) 1- 37- 62 5.285 Ocean-N-night V (2) 0- 55- 45 1.099 Ocean-6 m-day VI (3) 9- 91- 0 1.636 Bay-EB-day PL «D 100- 0- 0 0.382 York-EB-night T (100) 1- 17- 82

Euceramus praelongus I (58) 3- 89- 8 11.066 (2Z, PL) II (41) 36- 60- 4 9.060 PL (1) 100- 0- 0 1.002 T (100) 17- 76- 7

Eurypanopeus depressus I (56) 86- 14- 0 12.023 (4Z, PL) II (36) 88- 12- 0 1.456 III (8) 100- 0- 0 2.238 T (100) 88- 12- 0

Hexapanopeus angustifrons I(56) 8-90- 2 32.172 (4Z, PL) II (28) 15- 72- 13 18.808 III (11) 5- 66- 29 15.240 IV (4) 18- 55- 27 5.730 PL (1) 2- 98- 0 4.907 T (100) 10- 81- 9

Hippolyte Pleuracanthus I/T (100) 0-100- 0 0.3810.381 Bay-6 m-night (7Z, PL)

Libinia spp. I (91) 1- 11- 88 12.896 (2Z, PL) II (8) 0- 33- 67 1.684 PL (1) 0-100- 0 0.549 T (100) 1- 14- 85

Naushonia crangonoides I (83) 0- 3- 97 7.620 Ocean-N-night (5Z, PL) II (17) 0- 0-100 2.980 Ocean-6 m-day T (100) 0- 2- 98

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% Maximum density Species (Stages) Stage Distribution (location)

Neopanope sayi I (62) 86- 14- 0 87.295 York-1 m-day (4Z, PL) II (31) 76- 24- 0 23.646 York-N-night III (6) 41- 52- 7 3.005 York-EB-night IV (1) 42- 58- 0 1.002 York-EB-night PL « 1 ) 0-100- 0 0.167 Bay-N-night T (100) 80- 20- <1

Ocvpode quadrata I/T (100) 0- 0-100 1.497 Ocean-N-night (5Z, PL)

Ogyrides alphaerostris I (35) 81- 19- 0 1.175 Bay-EB-night (8Z, PL) II (22) 73- 27- 0 1.175 Bay-EB-night III (25) 77- 8- 15 1.983 York-1 m-night IV (5) 96- 4- 0 0.703 York-EB-night V (3) 100- 0- 0 0.251 York-3 m-night VI (5) 100- 0- 0 0.764 York-EB-night VII (5) 100- 0- 0 0.871 York-EB-day T (100) 81- 15- 4

Ovalipes ocellatus I (27) 0- 20- 80 2.203 Ocean-EB-day (5Z, PL) II (47) 0- 1- 99 17.276 Ocean-N-night III (10) 0- 0-100 1.875 Ocean-1 m-day IV (12) 0-0-98 2.580 Ocean-N-night V (4) 0- 0-100 1.914 Ocean-EB-night T (100) 0-6-94

Pagurus annulipes I (56) 0- <1-100 138.847 Ocean-1 m-night (4Z, PL) II (27) 0- 0-100 53.691 Ocean-1 m-night III (15) 0- 0-100 22.371 Ocean-1 m-night IV (2) 0- 0-100 4.258 Ocean-6 m-day PL « 1 ) 0- 0-100 1.684 Ocean-3 m-night T (100) 0- <1-100

Pagurus longicarpus I (60) <1- 91- 9 14.721 Bay-EB-day (4Z, PL) II (28) <1- 70- 30 8.852 Bay-N-night III (10) 4- 80- 16 3.448 Ocean-3 m-night IV (2) 26- 49- 25 1.875 Ocean-1 m-day PL « 1 ) 0-100- 0 0.173 Bay-EB-night T (100) 1- 83- 16

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% Maximum density Species (Stages) Stage Distribution (location)

Pagurus pollicaris I (77) 0- 0-100 17.276 Ocean-N-night (4Z, PL) II (11) 0- 10- 90 1.664 Off-EB-night III (12) 0- 0-100 3.328 Off-EB-night T (100) 0- 1- 99

Palaemonetes I (23) 94- 6- 0 5.010 York-N-night spp. (7Z, PL) II (29) 87- 13- 0 7.672 York-N-night III (25) 85- 15- 0 4.384 York-N-night IV (10) 62- 38- 0 2.004 York-N-night V (2) 59- 41- 0 0.467 York-N-night VI (5) 38- 62- 0 1.156 Bay-N-night VII (5) 25- 75- 0 1.156 Bay-N-night PL (1) 68- 32- 0 0.757 York-N-night T (1000 79- 21- 0

Panopeus herbstii I (81) 96- 4- 0 81.060 York-1 m-day (4Z, PL) II (13) 68- 32- 0 6.235 York-1 m-day III (1) 23- 77- 0 0.669 Bay-EB-night IV « 1 ) 0-100- 0 0.017 Bay-1 m-day PL (5) 2- 98- 0 3.083 Bay-N-night T (100) 87- 13- 0

Penaeus spp. I/T (100) 0- 0-100 0.988 Ocean-EB-day (6+Z, PL)

Pinnixa chaetopterana I (24) 39- 61- 0 42.725 Bay-6 m-day (5Z, PL) II (43) 52- 48- 0 68.698 Bay-EB-day III (22) 46- 54- 0 60.519 Bay-EB-day IV (8) 33- 67- 0 34.349 Bay-EB-day V (3) 9- 91- 0 27.806 Bay-EB-day T (100) 45- 55- 0

Pinnixa cylindrica I (50) 0-100- 0 5.648 Bay-EB-day (5Z, PL) II (29) 1- 90- 9 1.812 Bay-EB-day III (11) 0-100- 0 1.936 Bay-EB-night IV (6) 0-100- 0 1.238 Bay-EB-day V (4) 8- 92- 0 1.255 Bay-EB-day T (100) <1- 97- 3

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% Maximum density Species (Stages) Stage Distribution (location)

Pinnixa sayana I (26) 20- 79- 1 7.966 Bay-6 m-day (5Z, PL) II (31) 49- 51- 0 8.403 York-6 m-day III (23) 53- 47- 0 9.814 Bay-EB-day IV (12) 51- 49- 0 3.005 York-EB-night V (8) 63- 37- 0 3.271 Bay-EB-day T (100) 44- 56- <1

Pinnixa spp. PL/T (100) 65- 35- 0 3.005 York-EB-night

Pinnotheres maculatus I (50) 33- 63- 4 8.521 Bay-N-night (5Z, PL) II (26) 63-35- 2 7.595 York-EB-day III (12) 84- 16- 0 2.585 York-6 m-day IV (7) 72- 28- 0 1.497 York-6 m-night V (5) 97- 3- 0 2.486 York-EB-day T (100) 53- 45- 2

Pinnotheres ostreum I (37) 19- 81- 0 49.070 Bay-EB-day (4Z, PL) II (41) 6- 94- 0 58.656 Bay-6 m-day III (14) 2- 98- 0 29.442 Bay-EB-day IV (5) 2- 95- 3 13.085 Bay-EB-day PL (3) 1- 99- 0 7.538 Bay-N-night T (100) 10- 90- <1

Polyonyx gibbesi I (29) 94- 6- 0 2.333 York-3 m-day (2Z, PL) II (57) 98- 2- 0 2.486 York-EB-day PL (14) 100- 0- 0 1.000 York-EB-day T (100) 97- 3- 0

Rhithropanopeus harrisii I (2) 100- 0— 0 0.116 York-EB-night (4Z, PL) II (34) 26- 74- 0 1.095 Bay-EB-day III (48) 5-95- 0 1.883 Bay-EB-day IV (16) 0-100- 0 1.089 Bay-EB-night T (100) 13- 87- 0

Sesarma cinereum II (46) 100- 0- 0 2.486 York-EB-day (4Z, PL) III (36) 100- 0- 0 1.666 York-N-night IV (18) 100- 0- 0 0.372 York-6 m-day T (100) 100- 0— 0

Sesarma reticulatum III/T (100) 100- 0- 0 0.252 York-N-night (3Z, PL)

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% Maximum density Species (Stages) Stage Distribution (location)

Trachypenaeus constrictus II (37) 10- 90- 0 0.968 Bay-EB-night (8Z, PL) III (10) 0— 18- 82 0.241 Ocean-EB-day IV (40) 88- 12- 0 1.002 York-N-night V (13) 0-100- 0 0.385 Bay-N-night T (100) 38- 53- 9

Uca spp. I (9) 95- 5- <1 104.204 York-N-night (5Z, PL) II (42) 89- 11- <1 360.705 York-N-night n III (15) 80- 20- u 153.289 York-N-night IV (5) 65- 35- 0 49.986 York-N-night V (1) 52- 48- 0 7.014 York-N-night PL (28) 11- 89- <1 157.905 Bay-N-night T (100) 65- 35- <1

Upogebia affinis I (62) 43- 57- <1 36.788 Bay-EB-night (4Z, PL) II (21) 31- 57- 12 15.490 Bay-EB-night III (10) 14- 72- 14 5.809 Bay-EB-night IV (7) 10- 73- 17 4.702 Bay-EB-night T (100) 35- 60- 5

Xiphopenaeus kroyeri I (7) 0— 0-100 1.065 Ocean- ■6 m-day (9Z, PL) II (44) 0- 0-100 6.811 Ocean- ■3 m-night III (21) 0- 0-100 2.237 Ocean- ■1 m-night V (10) 0- 0-100 1.762 Ocean- ■N-night VI (7) 0- 0-100 2.036 Ocean- ■6 m-night VII (8) 0- 0-100 1.137 Ocean- ■6 m-night IX (3) 0- 0-100 0.831 Ocean- ■N-night T (100) 0- 0-100

Unknown A PL/T (100) 100- 0- 0 1.002 York-EB-night

Unknown B PL/T (100) 0— 0-100 0.685 Ocean-EB-night

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. APPENDIX F

Developmental Stage Distributions by Light and Depth.

Key

Roman Numerals = zoeal stages collected. PL = postlarva; T = total for species; N = neuston (0.10-0.15 m);l = 1 m; 3 = 3 m; 6 = 6 m; E = epibenthic (11-13 m)

212

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Alpheus heterochaelis

I 0 0 61 35 4 25 4 11 11 49 19 3 23 17 38 II 0 0 34 49 17 2 9 0 47 42 2 7 9 47 35 III 0 0 36 36 28 0 0 0 0 0 0 0 36 36 28 V 0 0 0 0 100 0 0 0 0 0 0 0 0 0 100 VI 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0 T 0 0 50 36 14 23 5 9 17 46 16 3 21 23 37

Alpheus normanii

II 0 100 0 0 0 0 0 0 0 0 0 100 0 0 0 III 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0 T 0 100 0 0 0 100 0 0 0 0 16 84 0 0 0

Callianassa atlantica

I 0 0 0 0 100 0 35 11 0 54 0 21 7 0 72 II 0 0 0 0 0 0 100 0 0 0 0 5 0 0 95 T 0 0 0 0 100 0 38 10 0 52 0 16 4 0 80

Callianassa biformis

I 0 1 1 30 68 1 9 19 15 56 <1 4 8 24 64 II 0 0 3 20 77 8 12 26 13 41 4 5 13 17 61 III 0 0 11386 5 12 27 13 43 2 5 11 13 69 IV 0 0 4 7 89 4 8 9 10 69 2 4 7 9 78 PL 0 0 0 0 0 4 10 36 25 25 4 10 36 25 25 T 0 <1 2 23 75 4 10 23 14 49 2 5 11 19 63

Callinectes sapidus

I 35 31 25 9 <1 33 53 13 1 <1 33 45 17 4 1 II 47 25 24 4 <1 29 63 7 1 <1 33 55 11 1 <1 III 52 24 22 2 <1 38 52 9 1 <1 44 41 14 1 <1 IV 62 18 17 3 0 48 46 6 <1 0 55 32 11 2 0 V 65 19 16 0 0 55 21 19 5 0 63 20 17 <1 0 VI 82 9 7 2 0 35 35 30 0 0 71 15 12 2 0 VII 76 9 15 0 0 14 65 21 0 0 61 22 17 0 0 VIII 85 0 0 15 0 31 69 0 0 0 56 37 0 7 0 PL 43 8 6 9 34 78 1 2 2 17 74 2 2 3 19 T 39 29 24 7 1 32 56 11 1 <1 34 47 15 3 1

Cancer borealis

PL/T 00 000 00 100 0 0 0 0 100 0 0

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% Day % Night % Total Stage N136E N136E N136E

Cancer irroratus

I 0 0 0 0 100 0 0 0 0 0 0 0 0 0 100 II 0 0 0 0 100 0 0 0 0 0 0 0 0 0 100 V 0 0 0 0 0 0 0 0 100 0 0 0 0 100 0 PL 0 0 100 0 0 0 0 0 0 0 0 0 100 0 0 T 0 0 53 0 47 0 0 0 100 0 0 0 39 27 34

Crangon septemspinosa

I 0 0 0 0 0 23 18 0 0 59 23 18 0 0 59 III 0 0 0 100 0 0 0 0 0 0 0 0 0 100 0 PL 0 0 0 0 0 0 0 0 0 100 0 0 0 0 100 T 0 0 0 100 0 14 11 0 0 75 13 10 0 6 71

Emerita talpoida

I 0 0 12 69 19 88 2 2 8 0 72 2 4 19 3 II 0 4 0 30 66 81 4 9 4 2 72 4 8 7 9 III 26 1 0 49 25 11 87 <1 2 0 13 76 1 7 3 IV 0 0 0 71 29 60 2 5 6 27 46 1 4 21 28 V 0 0 0 71 29 33 16 14 31 6 21 11 9 45 14 VI 0 0 0 0 100 6 14 18 0 62 3 8 10 0 79 PL 0 0 0 0 0 9 0 0 0 81 9 0 0 0 81 T 6 1 3 50 40 57 29 5 4 5 49 25 4 12 10

Euceramus praelongus

I 0 0 12 42 44 12 19 15 19 35 5 9 13 33 40 II <1 3 19 47 31 5 9 21 19 46 2 5 20 35 38 PL 0 0 0 33 67 2 5 0 0 93 1 4 0 4 91 T <1 2 15 44 39 9 14 17 19 41 4 7 16 33 40

Eurypanopeus depressus

I <1 8 34 46 12 83 0 0 6 11 55 3 12 19 11 II 0 6 43 28 23 8 8 19 34 31 5 7 30 31 27 III 0 0 0 0 0 10 0 0 6 84 10 0 0 6 84 T <1 7 38 38 17 55 2 5 13 25 35 4 17 22 22

Hexapanopeus angustifrons

I <1 10 14 39 37 45 9 15 13 18 23 9 14 26 28 II <1 17 12 41 30 36 8 13 13 30 20 12 13 25 30 III <1 8 9 44 39 47 4 16 13 20 30 6 13 24 27 IV <1 13 5 28 54 27 19 12 24 18 16 17 10 25 32 PL 0 0 3 0 97 26 8 6 11 49 10 3 4 4 79 T <1 12 12 39 37 42 9 14 13 22 22 10 14 25 29

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% Day % Night % Total stage N 1 3 6 E N 1 3 6 E N 1 3 6

Hippolyte pleuracanthus

I/T 0 0 0 0 0 0 0 0 100 0 0 0 0 100

Libiiiia spp.

I 0 12 3 34 51 35 13 13 8 31 22 13 10 17 II 0 0 16 54 30 27 6 48 0 19 13 3 31 28 PL 0 0 0 0 100 0 0 65 0 35 0 0 24 0 T 0 10 5 36 49 34 13 16 7 30 21 12 12 18

Naushonia crangonoides

I 0 0 0 51 49 58 0 12 11 19 51 0 10 16 23 II 0 0 0 77 23 0 0 0 0 0 0 0 0 77 23 T 0 0 0 68 32 58 0 12 11 19 42 0 8 27 23

Neopanope savi

I 1 70 13 9 7 74 8 3 7 8 39 38 8 8 7 II <1 33 19 13 35 62 6 6 11 15 30 20 13 12 25 III 15 12 13 34 26 6 3 18 22 51 12 8 15 29 36 IV 30 0 11 29 30 49 0 13 0 38 36 0 11 21 32 PL 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0 T 2 54 15 12 17 67 7 4 9 13 35 30 9 11 15

Ocypode quadrata

I/T 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0

Ogyrides alphaerostris

I 0 0 35 65 0 2 6 42 0 50 1 2 38 37 22 II 0 0 47 53 0 0 9 38 0 53 0 4 31 22 43 III 0 0 11 76 13 7 52 0 0 41 4 29 5 34 28 IV 0 0 76 0 24 0 0 0 29 71 0 0 24 20 56 V 0 0 0 100 0 0 0 100 0 0 0 0 69 31 0 VI 0 0 24 76 0 0 0 0 0 100 0 0 10 32 58 VII 0 0 0 32 68 0 0 0 0 0 0 0 0 32 68 T 0 0 27 62 11 2 18 23 2 55 1 9 25 31 34

Ovalipes ocellatus

I 0 0 2 20 78 5 3 2 15 75 3 1 2 17 77 II 0 0 0 25 75 59 0 15 11 15 48 0 12 13 27 III 0 65 0 35 0 0 0 0 0 100 0 23 0 12 65 IV 0 65 0 35 0 41 0 3 23 33 28 20 2 27 23 V 0 0 0 0 0 0 0 0 0 100 0 0 0 0 100 T 0 17 1 25 57 37 1 9 11 42 27 5 7 15 46

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% Day % Night % Total Stage N136E N136E N136E

Pagurus annulipes

I 2 7 34 32 25 14 43 11 8 24 10 31 18 16 25 II 4 12 39 30 15 6 44 21 4 25 5 33 27 13 22 III 23 21 25 27 4 13 46 5 6 30 17 35 14 15 19 IV 0 0 0 100 0 20 15 32 10 23 10 8 17 53 12 PL 0 0 0 0 C 0 0 100 0 0 0 0 100 0 0 T 7 11 32 32 18 12 43 13 7 25 10 32 20 15 23

Pagurus longicarpus

I 0 0 2 33 65 26 14 14 15 31 13 7 8 24 48 II 0 8 9 15 68 31 9 14 14 32 18 8 12 14 48 III 0 0 3 43 54 26 11 35 10 18 17 7 23 22 31 IV 0 87 0 1 12 14 10 11 6 59 9 37 7 4 43 PL 0 0 0 0 0 53 0 0 0 47 53 0 0 0 47 T 0 3 4 29 64 27 12 17 14 30 14 8 11 21 46

Pagurus pollicaris

I 0 0 0 39 61 62 18 10 7 3 50 14 8 14 14 II 0 0 0 40 60 9 0 8 36 47 5 0 5 38 52 III 0 0 0100 0 028 0 0 72 0 23 0 15 62 T 0 0 0 44 56 49 18 9 9 15 39 14 7 16 24

Palaemonetes spp.

I 36 43 21 0 0 74 13 4 8 1 72 14 5 8 1 II 15 70 15 0 0 83 11 2 3 1 80 14 3 2 1 III 9 10 22 27 32 85 12 <1 3 0 76 11 3 6 4 IV 3 8 12 22 55 76 6 0 0 18 68 6 1 3 22 V 0 100 0 0 0 94 6 0 0 0 78 22 0 0 0 VI 0 0 0 0 0 46 24 10 0 20 46 24 10 0 20 VII 0 0 0 16 84 60 40 0 0 0 40 27 0 5 28 PL 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0 T 9 24 14 16 37 78 13 3 3 3 73 14 3 4 6

Panopeus herbstii

I 1 84 9 3 3 60 7 4 21 8 15 66 8 7 4 II 3 43 20 20 14 46 0 13 25 16 17 30 17 21 15 III 0 100 0 0 0 30 18 0 0 52 30 18 0 0 52 IV 0 100 0 0 0 0 0 0 0 0 0 100 0 0 0 PL 0 0 0 43 57 73 2 5 15 5 63 2 4 19 12 T 2 78 10 5 5 59 5 6 20 10 18 58 9 9 6

Penaeus spp •

I/T 0 0 0 0 100 0 0 0 0 0 0 0 0 0 100

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% Day % Night % Night Stage N 1 3 6 E N 1 3 6 E N 1 3 • 6 E

Pinnixa chaetopterana

I 0 0 3 32 65 12 4 2 13 69 5 1 3 25 66 II <1 <1 4 22 74 17 4 2 15 62 7 2 3 19 69 III <1 <1 4 19 77 29 3 4 14 50 12 1 4 17 66 IV 0 0 3 18 79 36 2 3 11 48 12 1 3 16 68 V <1 0 1 7 92 31 i . 0 15 54 5 0 1 8 86 T <1 <1 4 23 73 20 3 3 14 60 8 2 3 19 68

Pinnixa cylindrica

I 0 1 2 53 44 51 19 13 14 3 11 5 5 44 35 II 0 0 5 34 61 32 5 0 11 52 16 3 2 23 56 III 0 0 0 54 46 40 3 0 9 48 31 2 0 19 48 IV 0 0 8 39 53 0 0 100 0 0 0 0 22 33 45 V 0 0 19 0 81 17 0 0 83 0 2 0 17 10 71 T 0 1 4 45 50 39 9 6 12 34 14 3 5 33 45

Pinnixa sayana

o I 0 1 5 36 58 23 Z. 3 11 61 8 1 4 28 59 II 0 1 6 44 49 23 2 / 20 48 8 1 6 36 49 III 0 <1 3 37 60 17 18 14 8 43 6 7 7 26 54 IV 0 2 8 36 54 14 6 16 16 48 8 4 12 25 51 V 0 0 8 37 55 12 11 16 17 44 6 5 12 27 50 T 0 1 5 39 55 19 7 10 15 49 7 3 7 30 53

Pinnixa spp.

PL/T 0 0 0 11 89 13 1 3 16 67 11 1 3 14 71

Pinnotheres maculatus

I 0 <1 7 35 58 34 15 6 5 40 18 8 6 20 48 II 0 1 8 27 64 34 <1 21 5 40 14 1 13 18 54 III 0 0 18 44 38 1 4 5 28 62 <1 2 12 38 48 IV 0 0 AsJ 42 58 5 0 5 38 52 2 0 2 40 56 V 0 0 0 25 75 0 33 15 14 38 0 20 10 18 52 T 0 1 8 34 57 27 11 10 10 42 13 5 9 23 50

Pinnotheres ostreum

I 0 <1 3 32 65 62 12 5 10 11 21 4 3 25 47 II 0 1 3 41 55 65 7 6 9 13 14 2 4 34 46 III 0 <1 2 35 63 54 9 14 9 14 9 2 4 30 55 IV 0 0 0 22 78 53 2 11 0 34 9 1 2 18 70 PL 1 1 0 15 83 82 0 5 9 4 57 <1 4 11 28 T <1 <1 3 36 61 64 9 6 9 12 17 3 3 29 48

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Polyonyx gibbesi

I 0 0 44 33 23 0 0 73 12 15 0 0 53 26 21 II 0 0 15 8 77 0 4 24 25 47 0 2 19 15 64 PL 0 0 27 20 53 0 0 0 22 78 0 0 15 21 64 T 0 0 26 18 56 0 2 31 22 45 0 1 28 19 52

Rhithropanopeus harrisii

I 0 50 50 0 0 0 0 0 0 100 0 33 33 0 34 II 0 0 24 27 49 42 0 0 30 28 8 0 19 28 45 III 0 0 2 34 64 51 0 0 42 7 15 0 2 36 47 IV 19 0 0 62 19 12 0 0 0 88 15 0 0 31 54 T 2 1 11 34 52 38 0 0 27 35 12 1 8 32 47

Sesarma cinereum

II 3 0 0 14 83 0 0 0 0 0 3 0 0 14 83 III 0 0 0 0 0 83 0 0 0 17 83 0 0 0 17 IV 0 0 44 56 0 52 48 0 0 0 22 20 26 32 0 T 3 0 8 21 68 78 8 0 0 14 35 4 5 12 44

Sesarma reticulatum

III/T 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0

Trachypenaeus constrictus

II 0 100 0 0 0 0 0 0 0 100 0 10 0 0 90 III 0 0 18 0 82 0 0 0 0 0 0 0 18 0 82 IV 0 0 0 0 100 100 0 0 0 0 88 0 0 0 12 V 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0 T 0 21 10 0 69 59 0 0 0 41 48 4 2 1 46

Uca spp.

I 17 19 35 14 15 86 4 4 2 4 77 6 8 4 5 II 7 49 24 10 10 84 9 3 2 2 68 17 7 4 4 III 3 39 26 11 21 85 7 3 3 2 65 15 8 5 7 IV 0 41 18 17 24 82 4 2 7 5 62 13 6 9 10 V 2 42 15 9 32 76 2 6 8 8 46 18 10 8 18 PL 2 0 <1 12 86 72 3 4 4 17 68 3 4 5 20 T 5 40 22 11 22 80 6 3 4 7 68 12 6 5 9

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Upogebia affinis

I 1 15 43 25 16 19 15 21 15 30 9 15 33 21 22 II 1 16 46 21 16 14 12 17 20 37 7 14 33 21 25 III 0 7 39 26 28 21 3 22 9 45 10 5 31 18 36 IV 5 9 27 32 27 12 7 17 13 51 8 8 23 24 37 T 2 13 42 25 18 18 13 20 15 34 9 13 32 21 25

Xiphopenaeus kroyeri

I 0 0 0 100 0 0 0 0 0 100 0 0 0 61 39 II 0 0 0 100 0 0 0 100 0 0 0 0 58 42 0 III 0 0 0 100 0 0 66 0 34 0 0 40 0 60 0 V 0 0 0 100 0 100 0 0 0 0 64 0 0 36 0 VI 0 0 0 0 0 0 0 0 100 0 0 0 0 100 0 VII 0 0 0 100 0 0 0 0 100 0 0 0 0 100 0 IX 0 0 0 0 0 100 0 0 0 0 100 0 0 0 0 T 0 0 0 100 0 16 13 41 26 4 10 8 25 54 3

Unknown A

PL/T 0 0 0 0 0 0 0 0 0 100 0 0 0 0 100

Unknown B

PL/T 0 0 0 0 0 0 0 0 0 100 0 0 0 0 100

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. AUTOBIOGRAPHICAL STATEMENT

Robert Copeland Maris was born in Marlin, Texas on 9 February,

1954. He received a Bachelor of Science in Zoology with honors from

Texas A&M University, College Station in December 1975 and a Master of

Science in Biology from the University of Southern Mississippi,

Hattiesburg in May 1980.

Honors, awards and positions held include: Phi Kappa Phi, Distin

guished Student Awards at Texas A&M University; Beta Beta Beta, Graduate

Teaching Assistantship at the University of Southern Mississippi; Doc

toral Fellowship, Sigma Xi, The National Dean's List, Academic Award for

Achievement and Service in Oceanography, Graduate Teaching and Research

Assistantship? at Old Dominion University.

Professional organizations: American Society of Zoologists, Asso

ciation of Systematics Collections, Biological Society of Washington,

National Shellfisheries Association, Society of Systematic Zoology, and

The Crustacean Society.

PUBLICATIONS

Maris, Robert C. 1979. Taxonomy and seasonal distribution of porcellanid crab zoeae (Crustacea: Decapoda: Porcellanidae) in the North Central Gulf of Mexico. Journal of the Mississippi Academy of Sciences, Supplement 24:120. (abstract)

Maris, Robert Copeland. 1980. Seasonal distributional and taxonomy of porcellanid crab zoeae (Crustacea; Decapoda; Anomura) in the North Central Gulf of Mexico. Master of Science Thesis, University of Southern Mississippi, Hattiesburg, Mississippi, 150 pp. (published by the Graduate School, USM)

Maris, R. C. 1982. Distribution of porcellanid crab zoeae (Crustacea, Decapoda, Anomura) in the North Central Gulf of Mexico. American Zoologist 22(4):950. (abstract no. 547)

Maris, Robert C. 1983. A key to the porcellanid crab zoeae (Crustacea, Decapoda, Anomura) of the North Central Gulf of Mexico and a com parison of meristic characters of four species. Gulf Research Reports 7(3):237-246.

220

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 221

Maris, Robert C. 1983. Larval distribution of porcellanid crabs (Deca- poda, Anomura) in the northern Gulf of Mexico. Association of Southeastern Biologists Bulletin 30(2):68. (abstract)

McConaugha, John R., David F. Johnson, Anthony J. Provenzano and Robert C. Maris. 1983. The seasonal distribution of larvae of Callinectes sapidus (Crustacea: Decapoda) in the waters adjacent to the Chesapeake Bay. Journal of Crustacean Biology 3(4):582-591.

McConaugha, J. R., R. C. Maris, D. F. Johnson and A. J. Provenzano. 1983. A descriptive model for offshore dispersal of larval blue crabs (Callinectes sapidus) and reinvasion into the lower Chesa peake Bay, Virginia. Association of Southeastern Biologists Bulletin 30(2):69. (abstract)

Feigenbaum, David L. and Robert C. Maris. 1984. Feeding in the Chaetognatha. Oceanography and Marine Biology: An Annual Review 22:343-392.

Maria, R. C. 1984. Effects of diurnal vertical distribution on decapod larval/postlarval dispersal strategies in the mouth of the Chesa peake Bay, Virginia. American Zoologist 24(3):38A. (abstract no. 209)

Maris, R. C. 1985. Diurnal vertical distribution of decapod larvae/ postlarvae in the Chesapeake Bay, Virginia, with effects on dispersal-recruitment mechanisms. American Zoologist 25:59A. (abstract no. 320)

Neal, Richard A. and Robert C. Maris. 1985. Fisheries biology of shrimps and shrimplike animals. Chapter 1, pages 1-110, In: Anthony J. Provenzano, Jr. (ed.), The Biology of Crustacea, Volume 10: Fisheries and Culture, Dorothy E. Bliss (editor-in-chief), Academic Press, New York.

Maris, Robert C. (in press). Larvae of Xiphopenaeus kroyeri (Heller, 1862) (Crustacea: Decapoda: Penaeidae) from offshore waters of Virginia, U.S.A. Proceedings of the Biological Society of Washington.

Maris, Robert C. (in press). Variations in dispersal patterns of deca pod crustacean larvae/postlarvae due to diurnal vertical distribu tion in the mouth of the Chesapeake Bay, Virginia. Journal of Shellfish Research.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 222

Maris, Robert C. and John R, McConaugha. (in press). Diurnal vertical distribution and dispersal-recruitment mechanisms of decapod crus tacean larvae and postlarvae in the Chesapeake Bay, Virginia and adjacent offshore waters. Journal of Shellfish Research.

McConaugha, John R. and Robert C. Maris, (in press). Spatial and tem poral variability of decapod larval distributions as regulating factors in estuarine decapod populations dynamics. Journal of Shellfish Research.

Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.