AGLAOPHENID HYDROIDS AND THEIR LI'ITORAL ENVIRONMENT
IN KEPPEL BAY, QUEENSLAND
Barry Eric Bryant
Thesis suhnitted for the degree of Master of Science, University of
New South Wales.
June, 1986. I hereby certify that this work has not been sul:mitted for a higher degree to any other
University or Institution •
Barry Eric Bryant I hereby declare that this thesis is my own work and that, to the best of my knowledge and belief, it contains no material previously published or written by another person nor material which to a substantial extent has been accepted for the award of any other degree or diploma of a university or other institute of higher learning, except where due acknowledgement is made in the text of the thesis.
Barry Eric Bryant TABLE OF CONTENTS
List of figures.
List of Tables.
List of Appendices.
Page
Sumnary
1. Introduction 1
2. Study Area 7
2.1 General 7
2.2 Topography 7
2. 3 Drainage 7
2.4 Climate 8
3. Study Sites 8
4. Hydrology 9
4.1 Sea Temperature 9
4.1.1 Technique 9
4.1.2 Results-Keppel Bay 10
4.1.3 Heron Island 10
4.2 Salinity 11
4.2.1 General 11
4.2.2 Technique 11
4.2.3 Discussion 12
5. Taxonany 14
Aglaophenia cupressina Lam. 1816 14 Halicornaria hians Busk 1852 18 Lytocarpus philippinus (Kirch.1872) 22
L.phoeniceus (Busk 1852) 25 Thecocarpus angulosus (Lam.1816) 28
6. Minor Survey Sites 30
6.1 Punpkin Island 30
6.2 Fitzroy River Estuary 32
6.3 Statue Bay 32
6.4 wave Point 33
6.5 Emu Park Beach 33
6.6 North-West Island 35 7. Major Study site:Ritamada Headland 36
8. Biology 37
8.1 Introduction 37
8.2 Environmental Tolerance 37 8.2.1 Exposure 37
8.2.2 wave Action 39
8.2.3 Shade 40
8.2.4 Spatial Orientation 41
8.3 Substrate 43
8.6 Growth 45 8.4.1 Colony Growth and Branching 45
8.4.2 Stolons 46 8.4.3 Regression 47 8.5 Reproduction 47
8.5.1 General 47
8.5.2 Regeneration and Stolonisation 48 8.5.3 Discussion 49 8.6 Nematocysts and Stinging Potential 52
8.6.1 Nematocysts of L.philippinus 52
8.6.2 Stin:Jing Potential 54
Conclusions 58
Acknowledgements 62
References 67
Appeooices 80 ----LIST OF FIGURES Facing Page
Fig. 2.1 Central Queensland Coastline 7
3.1 Keppel Bay study sites. 8
3.2 Exposure of Keppel Bay study sites. 8
4.1 Mean rronthly sea temperature and range in
Keppel Bay. 10
4.2 Yearly variation in mean sea surface
temperature for Townsville, Keppel Bay
and Moreton Bay. 10
5.1 Growth habit of A.cupressina. 15
5.2 A.cupressina - hydrothecal structures. 15
5.3 Growth habit of H.hians. 19
5.4 H.hians - hydrothecal structures. 19
5.5 Growth habit of L.philippinus. 23
5.6 L.philippinus - hydrothecal structures. 23
5.7 Growth habit of L.phoeniceus. 26
5.8 L.phoeniceus - hydrothecal structures. 26
5.9 Growth habit of T.angulosus. 29
5.10 T.angulosus - hydrothecal features. 29
5.11 T.angulosus - hydrothecal and sarcothecal
features. 30
6.1 Pumpkin Island Survey Site 30
6.2 Fitzroy River Survey Site. 32
6.3 Statue Bay Survey Site. 32
6.4 Wave Point Survey Site. 33
6.5 Emu Park Survey Site. 33 6.6 North-West Island Survey Site. 35
7.1 Ritamada Survey Site. 36
7.2 Keppel Bay offshore profiles 36 7.3 Relationships of rock strata to wind and
wave directions at Ritamada. 37
8.1 Percentage exceedance distribution of water
levels under tidal influence-Keppel Bay. 38
8.2 Time of monthly Lowest Low Water related to
mean monthly temperatures - Keppel Bay 39
8.3 Orientation of rock strata and the position
of site types of hydroid location. 39
8.4 Sites of attachnent of aglaophenid colonies
to rocky substrates. 41
8.5 Attachnent of branches and hydrocladia of
L.philippinus. 43
8.6 Morphology of aglaophenid branching 45
8.7 Nematophores and discharged mastigophores of
L.philippinus. 52
8.8 Nematocysts of L.philippinus 53
8.9 Tentacular nematocysts (atrichous isorhizas)
of L.philippinus 53
8.10 Sea temperature and aglaophenid stinging
potential. 56 ------LIST OF TABLES
Facing Page
Table 4.1 Maximum and minimum surface sea temperatures in Keppel Bay, 1980-1984. 10 8.1 Distribution of L.philippinus by site
types. 40 8.2 Length of main stem of L.phillipinus in
relation to degree of branching. 46 8.3 Published records of fertile colonies of aglaophenid species found in Keppel Bay. 48 LIST OF APPENDICES
Appendix I L.philippinus: lengths of main stem and first order branch in specimens bearing only first order branches.
Apperrl ix II L.philippinus: lengths of main stem, longest first and second order branches in specimens bearing two orders of branching.
Appendix II I Definition of clinical terms used in Section 8.8.
Apperrlix IV Table of Salinity Values in Keppel Bay February 1982 to June 1984.
Apperrlix V Sedimentation in Keppel Bay. SUMMARY
Intralittoral Keppel Bay species of aglaophenid hydroids (well known but rarely investigated causes of hunan injury) have been identified, aspects of their biology investigated and related to hitherto unpublished envirormental data.
New records for Keppel Bay of L.phoeniceus, H.hians and
T.angulosus are reported and the presence of L.philippinus confinned. Mean sea temperatures range fran 19.lC in June or July to 29.3C in January or February. Salinities range fran 25%0 to 42%0 fluctuating with seasonal evaporation and precipitation patterns and run off.
Hydroids occur seawards of mid-tide level. Colonies occur on gorgonian and rocky substrates in tidal pools below residual water level. At ELWS level, colonies tolerate an annual exposure of 3%.
Heavier colonisation occurs on the sheltered aspect of rocks and on sites offering minimum sedimentation and maximum trophic opportunity, especially the upper edges of rocks and on dead protruding remnants of gorgonian stems.
Surveys suggest that sexual reproduction is of little significance littorally due to envirormental stress and that larval recruitment occurs fran offshore stocks. Asexual reproduction fran a persistent stolon is a major means of colonisation. The presence of atrichous isorhizas (glutinants) and micro-basic mastigophores is demonstrated. Hunan stings caused by the latter nematocysts characteristically show delayed rather than inmediate urticaria, pruritus arrl vesiculation. A seasonal variation in virulence of both L.philippinus and L.phoeniceus is demonstrated, nematocyst sensitivity increasing at ambient water temperatures above
23C.
Literature is surrmarised and together with the results of this study, provides a basis for future research into Queensland aglaophenids in Keppel Bay and adjacent islands. An extension of this work would be an investigation of the ecological significance of offshore populations of aglaophenids canpared to the nearshore populations. 1 Introduction Aglaophenid hydroids cause human injury, well doc\Jlle(lted in both medical and zoological literature (Bale 1884, Baslow 1969, Bryant 1978, Coleman 1977, F.dmonds 1976, Keegan 1963, Russell 1965, Southcott 1963,1970,1975). Sane or all of the species cited, namely Aglaophenia cupressina Lamarck 1816, ~- mac,gillivrayi Kirchenpauer 1872 (= A. cupressina Laroouroux 1816) Lytocarpus philippinus Kirchenpauer 1872 and h. phoeniceus Busk 1852, may occur along the Central Queensland coast; the presence of allied species will almost certainly be confirmed by an appropriate investigatory programne. No published work has related environmental conditions in the Australian littoral zone and the biology of aglaophenid hydroids. This study aims to: (i) ascertain those species present in Keppel Bay; (ii) obtain information on basic hydrological data in Keppel
Bay; (iii) investigate the physico-chemical and biological envirorment in the littoral zone; (iv) study the biology of relevant species; (v) integrate old and new biological data on aglaophenid hydroids with ecological data in Keppel Bay. An extensive literature search including retrospective BIOSIS canputer-based research, showed that references to the morphology and biology of aglaophenid hydroids occur in general works on hydroids, such as those of Hadzi (1963), Hyman (1940), Lenhoff and Loanis (1961), MacGinitie and MacGinitie (1968), Muscatine and Lenl'x>ff (1974), Rees (1966). 2
A total of 365 references were found, dealing either with hydroid morphology, biology, systematics, general cnidarian biology or with the ecology and hydrology of marine, estuarine and intertidal environments. Of these, 197 were generated by the Biosis canputer research programne, a surprisingly limited number of references proving even broadly relevant, as many contained little more than the concept "hydroid". A number of foreign-language papers were cited in the canputer search and translation undertaken of a small number of
French and German texts, only those of Gravier (1970) and Meyer(l973} ultimately proving relevant. Fran this extremely wide spectrum of literature, more restrictive criteria provided 28 useful papers dealing with faunistic records, distribution and systematics, 5 with microtechniques, 17 with thecate hydroids in general, 6 with plumularian hydroids in particular, 10 with nematocysts and noxious effects, 24 with general ecology and biology and 13 with hydrology. Australian hydroid literature is mainly taxonanic descriptions of the late nineteenth and early twentieth centuries, in particular Bale's "catalogue of the Australian Hydroid zoophytes" (1884) and his subsequent works of 1888,1913, 1914, 1915, 1919. The very few descriptive works of later date include those of Hodgson (1950), dealing with Tasnanian species, Blackburn (1942) in South Australia and of local relevance, Pennycuick's Faunistic Records fran Queensland, Part V, (1959). Ralph's taxonanic works on New Zealand hydroids (1956, 1957, 1958, 1961a, 1961b, 1961c} and those of Millard (1958, 1962, 1975) on South African species are relevant, in parts, to the Australian 3 hydroid worker as sane degree of biogeographical continuity is acknowledged between the marine hydroid fauna of Australia, New
Zealand and South Africa (Blackbum 1942, Fraser 1940, Millard op.cit., Pennycuick op.cit., Ralph op.cit.,) Vervoort (1946,1968) and Van Gemerden-Hoogeveen (1965), although dealing with Caribbean species, have included two relevant cosmopolitan aglaophenids,
(L.philippinus and L. phoeniceus). Confusion exists in the systanatics of all hydroid families, despite the efforts of early isolated workers who lacked effective ccmnunication: modern biologists have comnunication and the benefit of hirrlsight in assessing the early taxonany. This problem has been acknowledged recently by the British
Museun, Natural History (Cornelius 1984,pers.comn.), initiating a long overdue international conference in 1985. Subject areas are:" hydrozoan systanatics and phylogeny; taxonanic characters and their interpretation especially at species, genus and family level; ecology and ••• phenotypic variation". This same author recently revised the British hydroid families Lafoeidae and Haleciidae (1975), Sertulariidae (1979), Campanulariidae (1982). The universal problem of synonymy in hydroid literature is illustrated by his findings that of over three hundred species of Campanulariidae in the north-eastern Atlantic, just twenty-three have proved valid (Cornelius 1982). Problems of taxoncmy were exacerbated by the ignorance of sane earlier workers of phenotypic variation. In rrore recent studies [Braverman (1974), Cornelius (1979), Gardiner (1972), Hughes (1977),
Highnam and Hill (1969), Lenhoff and Loanis (1961), Muscatine and Lenhoff (1974), Meyer (1973), Ralph (1956), Werner (1963)], 4 envirormentally-ioouced variations in the morphology of hydroid species and the influence on hydroid biology of ecological factors such as temperature, salinity, substrate, sedimentation, pollution have been recognised. Ecological studies involving hydroids have cacmonly centred around antifouling research [Hughes {1977), Pyefinch aoo Dowling
{1949), Sutherland and Karlsen {1977), Allen and Ferguson Wood {1950)]. Ecology of hydroids in Australian waters is described by
Shepherd and Watson {1970) and Watson {1973,1975,1978). General works on marine ecology relevant to intralittoral organisms include Bakus {1969), Cameron {1974), Jones and Endean {1973), Knox {1953,1963), Mariscal {1974), Meadows aoo campbell {1972), Perkins {1974), while Endean, Kenny and Stephenson {1956) have published a general survey of intertidal ecology along the mainland shores of Queensland. Hydroid records frcm Queensland are fragmentary at best, reflecting a poorly and unevenly collected coastline along which a few sites have been sporadically surveyed. The "Bibliography of Marine Invertebrates of Queensland", compiled by Dall arrl Stephenson {1953) lists 125 coelenterate publications, of which only eighteen refer to hydroids, between 1852 and 1942. Four main localities are mentioned over two thousand kilanetres, namely Torres Strait to Murray Island, Cairns and the Low Isles reg ion; Glcrlstone {Port Curtis) and the Capricorn Group of islands; Moreton Bay. Previous records fran Queensland were collated by Pennycuick {1959) in "Faunistic Records fran Queensland, Part V~arine and Brackish Water Hydroids", together with new specimens collected aoo recorded at that time. Pennycuick' s 5 area 4(a) contains records of thirty-two thecate and athecate hydroids of which thirty-one are recorded fran Port Curtis sane seventy-five kilanetres south of the study area, whilst only one record (L.philippinus) occurs for Double Head in Keppel Bay. Queensland Museum records are equally meagre, as their records " ••• date only fran the time of Pennycuick and no one has been working on hydroids since then ••• " (Cannon 1978, pers.ccmn.) Recourse must be made to overseas literature (in itself often inadequate), and information on systematics, life cycles, ecology and distribution is of necessity extrapolated. Within Central Queensland one investigation has been published involving such hydrological data in Keppel Bay as are relevant to beach protection and stabilisation, namely wind, wave and tidal data, coastal vegetation, sediments and coastal topography (Beach Protection Authority 1980). Two mainland environmental impact studies in Central Queensland coastal areas fringing Keppel Bay have also been reported in the literature, namely that of Hegerl and Tarte (1974) dealing with Capricorn Coast wetlands and that of the Capricorn Coast Protection Council (1974) on Corio Bay, sane twenty-two kilometres north of the present study area.
The lack of data on aglaophenid biology and on local envirorrnental paraneters has required that a broad appoach be followed with emphasis on local intralittoral conditions. The observations of Harnnond (1982) are apt " ••• marine biologists, unlike many other scientists •••• are obliged to ready widely ••• perhaps because the problems we encounter are multifaceted •••• individual piblications 6 cited most by marine biologists are those concerned with methods, or reference textbooks. This behaviour is characteristic of developing fields yet to achieve a discrete identity." Laboratory investigations of those species of hydroids easily maintained in aquaria have advanced our understarrling of hydroid biology, although this has frequently been at the cellular level. Aglaophenid hydroids are not easily kept in the laboratory, nor is it appropriate to undertake laboratory manipulations before basic envirormental parameters are delineated by field observations. Ecosystems vary, both in biological factors due to the presence of other organisms and by interaction with physical and chanical canponents of ,the environment. Alteration of one factor will alter others so wild organisms transposed to a laboratory envirorment will not behave "normally" (Mariscal 1974). The elucidation of aglaophenid ecology is of importance not only for the taxonanist but for the fuller understanding of marine biocoenoses. This study elucidates littoral envirormental corrlitions arrl their extremes sustained by intertidal organisms on the tropical eastern Queensland coast. Fig. ?. .1
10 20 30 40 50 60
Scale in kilometres
Central (Capricorn) Coast Q.Jeenaland. 7
2. Study Area 2.1 This is situated on the coastline of Keppel Bay, in the Fitzroy region of Central Queensland. The area lies at
Longitude 150 °49 1 East and at Latitude 23 16 South, some thirty kilanetres north-east of Rockhampton, the major
regional centre. The two coastal resort centres of Yeppoon
and Emu Park lie respectively at the northern and southern extremities of the area.(Fig 2.1) 2.2 Topography Keppel Bay is a drowned landscape, containing numerous continental islaoos within sane 20 kilanetres of the mainland.
The southern extremity of the bay is bounded by the estuary of the Fitzroy River, whilst the northern section consists of long sandy beaches and extensive, high dune formations. The general direction of the coastline is north and north-west. The presence offshore of the Great Barrier Reef, which extends as far south as 24°30'S, modifies swell and wave access.
2.3 Drainage Systems The Fitzroy River is the main drainage system. It is the
second largest coastal drainage system of the Queensland coast with a catchment area of some 14 million hectares (Pickard et al.1977). During the wet season, December to April, floods
are carmon and much sediment is transported seawards. Several minor drainage systems discharge into Keppel Bay. For 100st of the year they are tidal creeks but during the wet season are significant point sources of lower salinity water ~ ~ Pumpkin sland
151 E
Pt. 230S
Emu Park ~
0 0 C'Jrt is Is.
() KEPPEL BAY
Fig. 3.1 Study sites in Keppel Bay
Insert: North-!-lest Island,Great Harrier Reef. * : station site. Fig. 3 .2
N i
North Keppel Is
Pumpkin
I t.,TRve I • ! Point
i :
Pt.
Exposure of study sites in Keppel Ray 8
and sediment. 2.4 Climate The local climate is tropical to subtropical, the
influence of latitude being considerably modified by proximity to the sea. Air temperature cycles show a rnaximllil in December/January and a minimum in late July/August. The daily maxima along the coastal fringe are generally less than 30 and minima more than 14 C.
3 • Study Sites The main study site was at Ritarnada Point, while other
studies were undertaken periodically at Wave Point, Emu Park and Statue Bay, on the mainland (Fig.3.1) In aa3ition, surveys were carried out at one site on Pumpkin Island, a continental island situated some 15km north east of Yeppoon and also at North-West Islarxl, a coral cay on the Great Barrier Reef, some eighty kilanetres east of Keppel Bay. The rationale behind the selection of sites was as follows: (i) Ritamada Headland offered a fissured rock substrate, with sane sediment deposit, on a headland, exposed from the north to the south-east (Fig.3.2) (ii) Elnu Park canprised a fissured rocky substrate, with sane sediment, flanked to north and south by open beach and exposed fran the north to the south-east. 9
(iii) Statue Bay afforded a littoral zone of uniformly flat
topography with very heavy sedimentation, exposed only
from the north to north-east.
(iv) wave Point showed a flat profile, with sane
sedimentation, situated sane 600 metres southward of a
tidal creek, exposed fran the north to the east.
(v) Pumpkin Island provided access to seaward channels on
the eastern side of a bay island, with strong currents
and canpletely exposed on the weather side from north
to south-east. (vi) North west Island offered a coralline substrate with
minimal algal cover, with considerable exposure to
currents and wave action, in sediment-free water. 4. Hydrology
4.1 Sea Temperature
4.1.1 The importance of sea temperature in relation to the biogeographical distribution of marine flora and fauna in
Australia is generally acknowledged.
Hydrological data from official stations are not
available for Keppel Bay, the nearest station being at
Heron Islam, an oceanic site sane 100km south-east of the
study area. Sea surface temperatures were roonitored on a regular ~ basis at fortnightly intervals, using the technique of
Kenny (1974). A laboratory mercury thermaneter was used
to measure the water temperature in the top 25an of the Table 4.1
Table of maximum and minimum sea temperatures
in Keppel Bay. 1980-1984.
Year Maxima 0 c Minima 0 c Range oc Month -:remp. Month -Temp 1980 Januar~ 30.8 June 19.0 11.8
1981 January ;February 29. 0 July 19.8 9.2 '
1982 January 29.3 June ;July 19.0 10 .3
1983 February 28.5 July 18. l 10.4
1984 February 27.0 June 19.3 7.7 Fig.4 .1
...
' ;I 27 \ . 26
25
24 d "' Qj 23 Qj
! 22
21
2()
19
18
17
1�
J F M A J J A s 0 N Month Mean monthly aea tem&>erature and r•nge.leppel Bay. Fig. 4. 2
30 • • 1~:...... 11. • I ·,~·,. ./ • Koppel Bay "\,
c:J • /./· 0 QI k :, 25 ·1 t& k !. /. e QI /J· E-o ✓•~oreton i Ba • ;·.1/ . /" \ • ..,. ✓·1/ ./ 20 ·/ • • •I
\ ...... ,,,,,, . • 15
J F M A J J A S 0 N D Yearly variation in mean sea surface tempe·r11tures
0 Townaville,Lat.19°25'S. ;Keppel Bay,Lat,2l 2o'S; Moreton Ray, 2 7° J 'S. et :il(1977) nata for To•msville -'Ind :,t,reton R.
maxima to occur in January or February each year and minima for the corresponding period in June or July (Table 4.1). The annual mean maximum temperature was 28.9 C and
annual mean minimum temperature 18.5 C with an annual range of 10.5 degrees (Fig.4.1). In general, the sea surface temperatures in Keppel Bay were found to be below the ambient air maxima in sumner and autumn (December to April) and above ambient air minima during winter and
spring (July to November). Iooividual readings at the
study site, however, showed not unexpected variations in air temperature due to the effect of insolation on the
rock and sand strata, to the evaporative cooling effect of
wioos, and to the raiuction in water movement which occurred with a southerly or westerly canponent in wind direction. The annual range of temperature experienced in Keppel Bay is in substantial agreement with the temperature range found by Kenny (1974) at Townsville, of 9.9 C (Fig.4.2). The values obtained by Kennerly (1978) for the upper reaches of the Fitzroy River estuary in May 1974 (22 C), August (19 C) an::l November (23 C) are also in accord with the seasonal trends demonstrated in Keppel Bay. 4.1.3 Heroo Islam Sea surface temperature data for Heron Island were 11
made available from the CSIRO Division of Oceanography for the years 1980 to 1983. A mean maximum temperature of 26. 8 C and a mean minimum of 21. 5 C were shown together with a temperature range of 7 ° , maxima occurring in February or March and minima occurring in July or August. Seasonal trends in the temperature cycle are evident, although sea surface temperature showed more conservative values than in Keppel Bay. The time of maxima and minima showed a lag of approximately one month from those times
recorded in Keppel Bay. 4.2 Salinity 4.2.1 Queensland coastal surface salinity is a product of the four processes of evaporation, precipitation, continental water run-off and the mixing of coastal and oceanic water. No published data are available on salinity values in Keppel Bay and the nearest source of readings is Heron Island, sane 100km south-east from Keppel Bay. As Heron Island is an oceanic site, salinity values are much more stable than in Keppel Bay, the lowest recorded value being 35.15%0 and the highest 35.65%0 (CSIRO Divison of Oceanography 1984). 4.2.2 Salinity readings were taken at Ritamada Point at fortnightly intervals, using an Atago SC28 refractaneter. Results were confirmed with a Hamon thermosalinaneter (Autolab In:lustries Pty Ltd). Maxima of 40%0 to 42%0 were recorded in February to April of 1982 and although 12 uncomnonly high, gave no cause to doubt the accuracy of experimental procedure. 4.2.3 Discussion Within Keppel Bay, local processes of evaporation, precipitation and run-off are particularly important in causing sane extreme values in salinity. The large Fitzroy River at the southern extranity of Keppel Bay provides a seasonal influx of freshwater into the Bay, generally contributed in phase with the rainfall. The presence of small catchment areas draining through tidal wetlarrls into the bay, namely the Causeway, Fig Tree and Ross Creek canplex, Kinka Creek and cawarral Creek, provide adJitional point-sources of low-salinity water seasonally. Against this is large (unmeasured) evaporation, enhanced by the situation of Keppel Bay, on the Tropic of Capricorn, with high insolation and
persistent south-east wirrls. The rate of water loss is a function of wind speed. Salinity patterns in Keppel Bay follow seasonal rainfall distribution, maximum readings being obtained in late spring and early sumner prior to the ccnmencement of the tropical "wet season".
Inshore organisms in Keppel Bay may thus be exposed to extrane salinity values of 22%0 to 42%0 during the course of a year (Append.IV) experiencing a steady increase in salinity from late spring to sumner. They may 13 be subjected to abrupt and severe drops in salinity within a few days of heavy rain, but advective processes restore normal salinity values within two to three weeks, unless prolonged by flood run-off fran the Fitzroy River. 14
5. Taxonany
AGLAOPHENIA CUPRESSINA Lamouroux,1816
(i) Synonyms: Plumularia bipinnata Lamarck 1816 in [Bale, 1915) Plumularia MacGillivrayi (sic) Busk 1852 [Bale, 1915)
Aglaophenia MacGillivrayi (sic) Kirchenpauer 1872
[Bale,1884;1915)
Aglaophenia macgillivrayi (sic) Allman 1883
[Millard,1975)
Aglaophenia bellis Thornely 1900 [Bale, 1915) Aglaophenia macgillivrayi (Busk) (sic) [Hargitt, 1924 in
Briggs am Gardner, 1931)
Anisocalyx (Aglaophenia) cupressina
Costa 1838 [Bale, 1915)
Aglaophenia spicata Kirchenpauer 1872 [Bale, 1915 )
(not A.spicata Lamouroux 1816)
(ii) Descriptions: Descriptions of Australian specimens are available in Bale (1884), p.170;Plate XVIII,figs. 12-14, as A.macgillivrayi Busk; Bale (1915), p.319-327;Plate XLVII,figs 6-8. A further description is to be found in Millard (1975),p.408;Fig.128. , Fig. 5.1
Aglaophenia cupressina L amouroux,1816
(i) Growth habit
(specimen from North-West Island) Fig. 5. 2
Aglaophenia cupressina Lamouroux,1816
(i) Lateral view of hydrotheca
a. mesial sarcotheca
b. lateral sarcotheca
c. adcaul ine intrathecal septum
(ii) Vertical view of hydrotheca
a. lateral sarc otheca
b.mesial sarcotheca showing lateral lobes at distal extremity
c .cavity of hydrotheca
(specinen from North-,~st Islam) 15 (iii) Distribution: Millard (1975) notes that this species is found in the
tropical Indo-Pacific region from Zanzibar to the Great Barrier Reef and northwards in the Pacific to the Sea of Okhotsk. It has been recorded by Hargitt (1924 in Briggs
and Gardner, 1931) fran the Philippine Islands as A.macgillivrayi (Busk). Queensland records listed by Pennycuick include Murray Is., Thursday Island (in Torres Strait), Lizard Islarrl, June and Ribbon Reefs (North Queensland), Heron Island, Wistari and Hardy Reefs, North west Island (Capricorn and Bunker Group, Central Queensland). Bale (1884) has also recorded this species from the Louisade Archipelago to the north of Australia.
(iv) Occurrence in present study: Numerous colonies of this species were found on the exposed reef rim at North-West Island in the Capricorn Bunker Group off the Central Queensland coast.
(v) Diagnosis: Specimens fran North-West Island have been identified using the criteria of Bale (1915) and Millard (1975). Stan robust, thickly fascicled, pinnately disposed opposite branches in one plane, forming angles with the stan and large branches of about 50 ° (Figs.5.1;5.2). Hydrocladia short, alternate, one to each internode, 16 closely set, divided into squarish thecate internodes by transverse septa; two strong internodal septa. Hydrotheca deep, narrow, canpletely adnate; adcauline intrathecal septtnn across two-thirds of the cavity, margins irregularly sinuated or crenated. Mesial sarcotheca as long as the hydrotheca, canpletely adnate, with a thick intranematothecal septtnn; aperture tenninal with a rounded lobe on each side. Lateral nematothecae wide, tubular, curverl, over-reaching the thecal margin. 17
GENUS HALICORNARIA (Busk 1852)
Genus Halicornaria Allman 1874
Genus Gymnangium Hincks 1874
The generic name Halicornaria has been used in this work, following the usage of Bale (1884), Hargitt (1927), Millard (1958), Pennycuick
(1959), Ralph (1961) and Van Ganerden-Hoogeveen (1965)
Description: Shoots plumose, pinnate, often branched, rooted by a filiform stolon; hydrotheca generally toothed or lobed at the margin; a median anterior and two lateral sarcothecae connected with each hydrotheca, no others along the polypiferous ramules; gonotheca naked, on the main stem or the unaltered pinnae.
(Bale 1884) Bale further comnents that all the species described in the
Catalogue of Australian Hydroid Zoophytes (1884) possess small denticles projecting from the margin of the hydropore into the hydrothecal cavity, this point also being made by Ralph (1961,b) 18
Halicornaria hians (Busk,1852)
(i) Synonyms:
Plumularia hians Busk 1852 in [Bale, 1884] Halicornaria haswelli Bale 1884 [Bale, 1884]
Halicornaria hians (Busk) var.balei Billard 1913
[Van Ganerden-Hoogeveen, 1965]
Halicornaria Busk 1884 [Bale,1884]
Halicornaria flava Nutting 1906
[Van Gemerden-Hoogeveen, 1965] Halicornaria hians (Busk) var.profunda
Ritchie 1910 [Pennycuick, 1959] Aglaophenia balei Marktanner 1890 [Van Gemerden-Hoogeveen, 1965]
Halicornaria balei Ritchie 1910
[Van Gemerden-Hoogeveen, 1965] Halicornaria balei var.flava Ritchie 1912
[Van Gemerden-Hoogeveen, 1965]
(ii) Descriptions:
Australian descriptions are in Bale (1884),p.179;Plate XIII,fig.6; Plate XVI,fig.7;Pennycuick (1959),p.186; as H. Haswelli in Bale 1884, p.180-18l;Plate XIII,fig 5; Plate XVI,
fig 8. Additional descriptions are available in Millard
(1958), p.219-220; van Gemerden-Hoogeveen (1965),p.70-73; Millard, 1975, p.433. Fig. 5.3
Halicornaria hi ans ( lbsk, 18 52)
(i) Growth Habit
(ii) Vertical view of hydrotheca
a.mesial sarcotheca
b.cavity of hydrotheca
c.intrathecal ridge t d ,denticles on intrathecal ridge
(iii) Lateral view of hydrotheca Fig. 5.4
Halicornaria ~ (Busk, 1852)
(a)
a.rresial sarcotheca • b,abcauline intrathecal ridge
c.pronounced lateral teeth
d .denti.cles surrounding aperture into pinna
e.lateral sarcotheca
specirren from Keppel Bay
Fig. 7.6
(b) /1
canaliculate aperture of rresial sarcotheca,due to confluent
terminal and lateral apertures. (Keppel Bay specirren) 19 (iii) Distribution: This species has been recorded fran the Indian and Pacific Oceans and as var.balei from the Rerl Sea (Van Gemerden Hoogeveen, 1965) whilst Australian distribution records show
Torres Strait, Murray Islarrl, Port Curtis (as H.haswelli) and Wistari Reef (Pennycuick, 1959).
(iv) Occurrence in Keppel Bay: One detached specimen of this species was found on a flat, intralittoral algal-rubble zone on the western (sheltered) side of Pumpkin Island, Keppel Bay (iv,1982).
(v) Diagnosis: The colony of H.hians (Busk, 1852) consisted of thirty eight unbranched stens attaining heights of 200 to 223mn, arising in close juxtaposition from a thickly convoluted and anastanosed stolon mass 90mn in length and 20mn wide (Fig.5.3). The stens were of a reddish-brown colour, the hydrocladia being light golden-brown. The hydrocladia arose from the stem two to each internode and were approximated at an angle of 80 ° to each other, each hydrocladium making an angle of 55 0 to the sten, alternate or subalternate. The specimen fran Keppel Bay agrees with the description of Bale (1884) in the following details (Fig.5.4): the sten is monosiphonic;pinnae approximate; alternate or subalternate, two to each internode. Hydrotheca wide apart, 20 set at an angle of aoout 55 ; a strong abcauline intrathecal ridge; aperture with three large lateral teeth on each side, directed sanewhat to the back of the cell; back entire, free; aperture between cell and pinna surrounded by minute slender denticles. Mesial sarcotheca adnate to the front of the hydrotheca nearly up to the margin, free part small, pointed, canaliculate, scarcely rising as high as the teeth of the hydrotheca. Lateral sarcothecae small, adnate, saccate, with a wide lateral aperture. Sane variability in height of the mesial sarcotheca was noted in the Keppel Bay specimen, such variation agreeing with that noted by Millard (1958). 21 GENUS LYTOCARPUS Key to Species 1. Hydrothecae without abcauline marginal tooth, but with two or more pairs of lateral teeth L.phoeniceus - Hydrotheca with an abcauline marginal tooth and
ooe pair low lateral teeth. • •••••••••• 2 2. Segments of hydrocladium sharply denarcated on posterior surface and often produced as a spine. Abcauline thecal tooth equal to or longer than the lateral teeth. Abcauline intrathecal septum reaching about one-third distance across hydrotheca. L.filamentosus - Segments not sharply denarcated on posterior surface. Abcauline thecal tooth shorter than lateral teeth. Abcauline intrathecal septum
reaching halfway across hydrotheca. L.philippinus
{after Millard, 1975) 22
Lytocarpus philippinus (Kirchenpauer, 1872)
(i) Synonyms: Aglaophenia urens Bale, 1884 [Bale 1884] Lytocarpus crosslarrli Ritchie, 1907 [Van Generden, 1965]
Macrorhynchia philippina Stechow & Muller, 1923 [Gravier, 1979] [Van Generden-Hoogeveen, 1965] [Vervoort,1968] Aglaophenia philippina Kirchenpauer 1872 [Vervoort,1968] Plumularia scabra Lamarck [Bale, 1884] Lytocarpus urens Bale, 1888 [Bale, 1888] Macrorhynchia philippinus (sic) Vannucci 1946 [Vervoort, 1968]
(ii) Descriptions: Descriptions of Australian specimens are to be found in Bale 1884,(as A.urens,not Kirchenpauer) p.155,Plate XIV,Fig.6;Plate XVII,Fig.9;Bale 1888,p.786.Plate XXI,Figs.5,6;Bale 1919,p.351 and in Briggs and Gardner 1931,p.193,Fig.4. Additional descriptive material occurs in Millard 1975,
p.451-452;Fig.138A~; Vervoort 1968 pp 88-90;Fig.41; Vervoort 1946,p.329-330;Van Generden-Hoogeveen 1965,p.14-16. Fig. 5.5
Lytocarpua philippinua (Kirchenpauer, 1872)
(i) Gro~h habit
(ii) Lateral view of hydrotheca
a. lateral sarcotheca
b.hydrotheca
c .strong abcauline intrathecal ridge
d.neaial sarcotheca
e.small adcauline intrathecal ridge
f. hydropore
g. abcauline tooth (Keppel Bav specimen.) Fig. 5. 6
Lyt ocarpus philippinus (Kirchenpauer 1 1872)
a
Vertical view of bydrotheca
a. Lateral ,sartothec,a
b.cavity of hy~rotheca
c.abcauline intrathecal septum
d.mesial sarcotheca
e.lateral aperture of sarcotheca
(specimen from Keppe 1 Bay) 23
(iii) This species has a very wide distribution in the tropical and
subtropical Atlantic, Pacific and Indian Oceans and the
Mooiteranean Sea (Vervoort, 1946). Within Queenslaoo, the
species has been extensively recordoo fran Torres Strait to
Moreton Bay (Pennycuick, 1959). Type Locality: Manilla,
Philippine Islands.
(iv) Ocx:::urrence in Keppel Bay:
Numerous colonies of this species have been found in
Keppel Bay from mid-littoral to infralittoral levels, attached
to rocky substrates. (It has also been recorded during the
present study from North-West Islam on the Great Barrier
Reef).
(v) Diagnosis:
Specimens fran Keppel Bay agree with the description of
Bale (1884) (as Aglaophenia urens Kirchenpauer, 1872) and with
those of Millard (1975), Vervoort (1946,1968), Van Ganerden
Hoogeveen (1965) and Bale (1888) (as L.philippinus)
(Figs.5.5;5.6)
Stem polysiphonic, although young colonies have
unbranched aoo monosiphonic (unfascicled) stems, this point
not being mentioned by Bale (1884) but verified by reference
to Millard (1975) and Vervoort (1946). Pinnae are short,
alternate, one to each internode, springing fran the front of
the stem. Hydrothecae parallel with the pinna in their
longest diameter; deeply constricted between the aperture and
the mesial sarcotheca aoo abruptly recurved so that the 24 aperture is vertical; aperture wide; sides slightly elevated with a scarcely perceptible angle in the middle of each.
Briggs and Gardner (1931) depict the hydrotheca as having distinct lateral lobes with pointed lateral teeth, but the Keppel Bay specimens are similar to those of Bale (1884) , Millard (1975) and Vervoort (1968). The abcauline median tooth is well developed and is continued basally with a thick abcauline intrathecal ridge; a small adcauline intrathecal septum; hydrothecal internode with
two septa or constrictions. Mesial sarcotheca adnate to the hydrotheca as far as the abcauline intrathecal septum; nearly double the height of the hydrotheca; with three apertures, one tenninal, one lateral at the base of the free part and one into the hydrotheca. Lateral sarcotheca tubular, divergent, crlnate to the hydrotheca as far as the margin and rising above it, inclined at approximately the same angle as the mesial sarcotheca. "The arrangement of branches on the stem is very irregular: usually there are two rows, in one plane or displaced anteriorly, with variable intervals between them, oi;:posite, alternate or quite irregular" (Millard, 1975). 25
Lytocarpus phoeniceus (Busk, 1852)
(i) Synonyms: Plllllularia phoenicea Busk 1852 [Bale 1884] Aglaophenia phoenicea Bale 1884 [Bale 1884]
Aglaophenia rostrata Kirchenpauer [Bale 1884] Lytocarpus spectabilis Allman 1883* [Millard 1975] Lytocarpus phoeniceus Billard 1910 [Millard 1975] * synonymy contested by Hargitt (1927) [in Vervoort,1946].
(ii) Descriptions: Descriptions of this species are to be found in Bale (1884) EP
159-16l;Plate XV, Figs.l-5;Plate XVII, Figs.l-4;Plate XIX, Fig.31, (as Aglaophenia phoenicea); in Millard (1975) w 451- 453; Fig.137D; Briggs and Gardner (1931),p.194;Fig.5; Vervoort (1946), pp 328-329.
(iii) Distribution: Lytocarpus phoeniceus is a tropical Indo-Pacific species, fran the Pacific Ocean to the east coast of Africa (Millard, 1975) and particularly comnon in the East Indies (Vervoort, 1946). A single Atlantic record is believed to refer to Halicornaria montagui (Billard, 1912) rather than L.phoeniceus. (Vervoort, 1946). This species has been recorded in Queensland fran Torres Strait to Moreton Bay (Pennycuick, 1959). Fig. 5. 7 Lytocarpua phoeniceua (&lsk, 1852)
(i) Growth Habit
..
(ii) Hydrotheca-lateral view
a. mesial sarcotheca
b. posterior adcaulire tooth
c. intrathecal abcauline septum
d. lateral aarcotheca
e. adcauline intrathecal septum f. lateral aperture of aarcotheca.
(apecinen from Keppel Bay) Fig. 5.8
Lytocarpus phoeniceus (lklsk, 1 $352)
Vertical view of hydrotheca
a b a
a. lateral sarcotheca
b. adcauline tooth
c. cavity of hydrotheca
d. mesial sarcotheca
e. lateral marginal tooth
(specit'll!n from lCeppe 1 Bay) 26
(iv) Occurrence in Keppel Bay: Colonies of this species have been found on two occasions at
Emu Park, at mid-littoral levels on rocky substrates, and also attached to a fragment of staghorn coral in the Fitzroy River
estuary.
(v) Diagnosis: Specimens of this species fran Keppel Bay have satisfied the criteria in Bale (1884) (as Aglaophenia phoenicea), and Millard (1975) (Figs.5.7;5.8). Stem fascicled, bipinnate, OEl)()Site to alternate branching in one plane; hydrocladia alternate, arising from the front. Hydrothecae parallel with the pinnule in their longest diameter; a slight constriction
near the base adcaudally, an intrathecal ridge projecting downwards fran between the front of the aperture and the mesial sarcotheca nearly through the cell; aperture at a snall angle with the pinna, sub-crenate, each side forming a broad sub-angular lobe, sanetimes a snall abcauline median tooth. (Although Millard does not record an abcauline tooth in this species, the figure shown in Briggs and Gardner (1931, Text.fig.5) shows the base of the abcauline intrathecal septum irregularly protruding at the base of the median sarcotheca, consistent with the Keppel Bay specimens); rounded lobe behind margin, sanetimes produced into a tooth. Hydrothecal internode with two constrictions. Mesial sarcotheca long,
adnate nearly as far as the aperture, free part variable in 27 lergth, tapering, projecting forward at an angle, with distinct lateral and terminal apertures and a small opening into the hydrotheca. The lateral nanatothecae, according to Bale, are either adnate and directed upward, or large free and directed downwards from the hydrotheca and this respect the Keppel Bay specimens are similar to Bale's Plate XV.Fig.3 from Port Molle. 28 Thecocarpus angulosus (Lamarck 1816)
(i) Synonyms: Aglaophenia Huxleyi Busk 1849 (sic) in [Bale,1884] Aglaophenia angulosa Lamouroux [Bale,1884] Plumularia angulosa Lamarck 1816 [Bale,1884] Plumularia Huxleyi Busk 1849 (sic) [Bale,1884] Acanthocladium angulosum Stechow and Muller 1923 [Briggs and Gardner,1931]
Acanthocladium studeri [Pennycuick,1959] Acanthocladium huxleyi (sic) [Pennycuick,1959]
(ii) Descriptions:
Australian descriptions of this species are to be found in Bale (1884),p.161-162;Plate XV,Fig.6;Plate XVII,Fig 8; Briggs and Gardner (1931),p.192-193; Fig.3.
(iii) Distribution: Previous Australian locality records for the species are enlll\erated by Bale as Port Curtis, Port Molle at 15 fathans, Port Denison (1852). Briggs and Gardner (1931) reported nlll\erous colonies at depths of 10 to 28 fathoms from dredging stations off the north-east coast of Queensland during 1928- 1929. These localities are sumnarised by Pennycuick (1959) (Table l,p.151) as extending from 10 0 to 26 0 S Lat. 'Fig. 5. 9
Thecocarpus angulosus(Lamarc k 1816)
(i) Gt'owth habit
( ii ) Symp o:l ial phyl lot axis 2
____120° 1;4
120°
(iii) Hydrotheca
specimen from 'Keppel 'Say (vii, 1979) Fig. 5.10
Thecocarpus angulosus (.Lamarck 1816)
speciman from Keppel Bay (vii, 1979)
a. masial sarcotheca
b. intrasarcothecal ridge
c .orifice into hydrotheca
d .abct·auline intrathecal ridge'
e. acute tooth
f. lateral sarcot heca
• 29 (iv) Ocxurrence in Keppel Bay: One colony was collected by I Prowse (vii.1979) at Wave Point attached to a rocky substrate at the level of ELWS.
(v) Diagnosis: The colony canprised three erect stems attaining a maximWI height of 120mn, arising from a filiform stolon attached to the rocky substrate. The stem is thick, fascicled (polysiphonic), flexuose, giving rise to "branches" fonned by sympodial pinnae. The main axis of the stem rises in a spiral manner, as each "branch" or sympodium gives rise to the subsequent one fran its anterior surface and twists spirally. The angle of divergence of subsequent sympodia was 120 0 , that is, the fourth sympodium lay directly above the first (Fig.5.9) and the circumferential distance between two consecutive sympodia was therefore 1/3. The modal distance between flexures was 4mn, each "branch" then giving rise to close-set hydrocladia, arising alternately, one to each internode, from the anterior aspect, making an angle of approximately 55 ° with the sympodium. The specimen agreed with the description of Bale (1884) in the following details (Fig.5.10). The hydrothecae are cup-shaped, the lower half abruptly constricted anteriorly, an intrathecal ridge projecting
downwards from the mesial sarcotheca nearly through the cell; aperture vertical, subcrenate, sides not elevated, back Fig. 5.11
Thecocar pus angu losus (Lamar ck 1816)
(i) Hydrotheca-vertical
a
a. lateral sarcotheca
b. hydrotheca
c. abcauline intrathecal ridge
d.mesial sarcoth~ca
(ii) Lateral sarcothecae
(a) (b)
(a) Sarcotheca from distal extremity of hydroclad ium
(b) Sarcotheca from proximal extremity of hydrocladium Fig. 6-• l Pumpkin Island,Keppel Bay.
N
North Keppel Is •
.. .
Yeppoo q km. r
i
sand ,.. and algal rubble flats
pre~ling wind and swell
#- Site of H.hians
~•----• 100m. 30 broadly sinuated nearly down to the pinna, a snall praninent acute tooth in front. Mesial sarcotheca about twice as high as the hydrotheca, adnate to it as far as the aperture, free part beak-like, curved forwards, rapidly narrowing UP'flards from back to front, but widened laterally at the sumnit, canaliculate. Bale's description of the lateral sacrcothecae
soows them to be short, broad, adnate, directed downwards from the hydrotheca, with a wide margin extending under the whole front margin. Briggs and Gardner (1931), oowever, make the point that the lateral sarcothecae are extremely variable, those near the distal end of a hydrocladium being short and broad with a distinctly crenulated margin, a gradual change in shape taking place until those at the proximal portion of the hydrocladium have becane drawn out into long tubular
structures. The specimens from Keppel Bay show the variation in lateral sarcothecal characters described by these latter authors. Although not in Bale's written description, both his
figure (Plate YN, Fig.6) and that of Briggs and Gardner (op.cit., Text-Fig.3) show an intrasarcothecal ridge which was also present in the Keppel Bay specimens (Fig.5.11). 6. Minor Survey Sites 6.1 Pumpkin Island Pumpkin Island is a continental island lying 12km north-east
of the mainland resort of Yeppoon (Fig.6.1). Surveys were
conducted in May 1982 and April 1983, the survey site being
located on the south-easterly aspect of the island and in 31 consequence, exposed in all but the calmest weather to incessant wave action under the influence of the prevailing south-east wims. Tidal streams attain a speed of approximately 5km per hour due to the topographical constricting effect on water flow of adjacent islams. As a result of this continual vigorous water movement, no sediment is apparent on rocks at the study site, which were however covered with a dense growth of brown algae (Sargassum ~-) below the level of Mean Low Water. Encrusting coralline algae were prevalent on rocks fran MLW to mid-littoral level, while residual rock pools contained heavy deposits of coarse calcareous sediment. Results: No living aglaophenid hydroids were found during either survey of this exposed site, although a few non-plumularian hydroids were observed under subtidal rocks. One unattached dead specimen of Halicornaria hians was obtained from a flat algal and rubble covered intralittoral bench on the western (sheltered) side of the island. Discussion:
The extreme water turbulence normally present is considered a limiting factor in aglaophenid distribution at this site, exacerbated by the violent movanents of the brown algae and also the scouring effect of coarse particulate matter, under the influence of swell and tide. Fig. 6.2
5km Emu Park i
Cawarral Cr. .. .
Keopel
Curtis Isbmi
Fitzroy River dredging site. Fig. 6 .3
STATUE BAY STUDY SITE
N T ...
Statue dluf\.ck
predominant 1 km ~ dire et ion of wi nd and s 'toe 11
ii indic.'¼tes position of transect for sediment samples
'• ~
.' 32
6.2. Fitzroy River Estuary One specimen of L.phoeniceus was dredged fran the estuary of the Fitzroy River, during September, 1983 (Fig.6.2), attached to a large (400nm) fragment of staghorn coral
(Acropora ~) which was almost entirely covered with encrusting coralline algae. This living specimen had attained
a main stem len:Jth of 65nm with two side branches of 8nm and 11nm and was firmly attached by a matted stolon. The use of
dead coral substrates has been previously documented (Bale, 1884; Briggs and Gardner, 1931) fran offshore sites. Turbidity is very high in the estuary of the Fitzroy River as flocculation of suspended silt and consequent sedimentation occur in the lower reaches. Such turbidity had no overt effect on the viability of the specimen of L.phoeniceus fourrl, the scouring effect of tidal ebb and flow in mid-channel probably preventing this specimen fran being snothered by silt.
6.3 Statue Bay This study is characterised by a flat littoral bench, protected from all except north to north-easterly wirrls and wave action. Fran the north-east to the south it lies in the wave energy shadow of Double Heads arrl Rosslyn Bay boat harbour. This site is subject to very heavy sedimentation due not only to its sheltered position but also to the zone of wave interaction due to refraction around the Keppel Islands, located just offshore (Fig.6.3). Fig. 6.4
WAVE POINT STUDY SITE
N
... f
ominant ect ion of nd and s W:? 11
1 km
I Position of transect •
• Fig. 6 ·5
N T ... b f,: Pelican Is.
~ ~-red ge Is. Zilzie Point ~ if" () Mother MacGregor Is. ~ @ Divided _Is~ ' 1 km
Emu Park study site •
.-
! 33 Samples of sediment were taken fran this site for canparison, the results being shown in Section 4.6. The very heavy sediment cover has severely limited the number and variety of macroscopic organisms present. No hydroid colonies were noted during this survey. 6.4 wave Point The topography at Wave Point shows a relatively sheltered flat littoral bench, with an intertidal slope of 1:50, reducing to 1:250 offshore (Beach Protection Authority 1980). This reduction in slope is associated with a reduction in sediment particle size and, coupled with the proximity of Ross Creek sane 600m to the north, is responsible for the fine sediments characteristic of the area (Fig.6.4). This area was surveyed during July 1982, when numerous specimens of L.philippinus were found seawards of the midtidal level. All specimens were attached to rocky substrates, either from the vertical sides or shoulders of the rocks, below water level in tidal pools. Colonies attained a mean main stem size of 45rnn (n=24), with extrane values of 25 and 60rnn. One colony of Thecocarpus angulosus Billard 1913, 110rnn high, was found (I.Prowse, vii, 1979), attached by an anastanosed stolon to a rocky substrate at the level of ELWS. 6.5 Elnu Park
This area, the roost southerly mainland study site in Keppel Bay was surveyed during May arrl October 1983 (Fig.6.5). 34
The site canprises a deeply eroded and fissured rocky area flanked on either side by sandy beaches. Numerous sandy floored rock pools retaining sane 300mn of water at low tide are present within the study area which shows an intertidal slope of 1:30, reducing seawards of low water to 1:60 (Beach Protection Authority 1980). Proximity to the Fitzroy River estuary to the south and to offshore deposits of fine terriginous material, is responsible for a layer of fine sediment covering the site. Sediment distribution at the study site and canparisons with other sites may be found in Apperrlix 5. This site is exposed to wave action fran the north to the south-east, although sheltered from extremes of water turbulence by the presence of offshore islands which limit the fetch of the daninantly south-east wirrls. In comnon with other Keppel Bay sites, the rock strata lie obliquely to the daninant wirrls and waves, thus producing an exposed eastern and southern aspect and a protected northern and western aspect. Colonies of L.phoeniceus were found on each survey, in permanent rock pools below residual water level, in the mid littoral zone. Colony heights were 56mn, 60mn and 42mn, each colony showing only one degree of branching and being attached to rock substrate by a convoluted and anastanosed stolon. Numerous colonies of L.philippinus were observed Fig. 6 .6
A. North-West Islard,G.B.R.
N T
transe
reef rim --1 OOOm.
B.Diagrammatic cross-section of reef and cay.
reef rim ft rubble zone ..-----_____.o_..0Jii""az.t2k~~-;*~=--~-- .>1. L. fv. ~g rl sand// flat /cay / coral clumps moat
f~ site of A.cupressina colonies
* site of L.philippinus colonies 35 attached to both gorgonian stems and also to the upper edges of rocks, below residual water levels. Colonies were more nlil\erous on the sheltered western and northern aspects of the rock strata than on the more exposed eastern and southern faces. A full discussion of this distribution of colonies is
detailed in Section 8.4.1. During the survey of May 1983, 25 colonies of L.philippinus showing two degrees of branching, recorded a mean main stem height of 68mn with a range of 45 to 100mn. In October the mean main stem height of a sample of 25 colonies was 61.9mn with a range of 51 to 98mn. Both these observations appear to conform with the more extensive samples taken at Ritamada Headland. 6.6 North-West Island North-West Island is a true coral sand cay, 80km ESE fran Keppel Bay, towards the southern extremity of the Great
Q I O I Barrier Reef (23 15 S.Lat,151 45 E.Long). The densely vegetated cay measures only 800m by 1300m but reef area is approximately 38km (Fig.6.6). A moderate oceanic swell of 1 to 3m. prevails on the weather (south-east) side and wave action is always vigorous. The lee side is calmer, but vigorous water movement at the reef rim prevails frommid flood to mid-ebb tides. At low tide the massive consolidated reef rim lies canpletely exposed whilst a residual water depth of sane 750mn may exist over the outer reef flat adjacent to the reef rim. Fig. · 7 .1 R IT AMADA POINT STUDY SITE
N i
MUD FLATS of
predomin nd and lole 11
1 km.
!> Study site •
·, Fig.7 .2
N i
Liv. 2140
15 1 S.
-:--L-1v..:•....:.:19:,.::9__!,(,:_97c:~oo')
Off-shore profiles in Keppel Bay. { after Queensland Department of Harbours and Marine) These profiles coincide closely with study site transects. {Profile numbers and bearings from Dept.Harbours and Marine). 36
A survey of this site during June,1983 yielded two aglaophenid hydroids, namely Lytocarpus philippinus (Kirchenpauer 1872) arrl Aglaophenia cupressina Lamouroux 1816. (i) L.philippinus was found in widely scattered single colonies along the inner reef rim rubble zone, attached to the lower side of coral boulders and also in the
interstices of coral clunps (Acropora §EE_.) in the 100at zone larrlwards of the reef rim. Fourteen colonies were
found below residual water levels and had a mean main stem length of 48mn (range:40-63mn). (ii)A.cupressina colonies were found growing canpletely exi;x:>sed, on the northern aspect of the reef, sane 30m shorewards from the outer edge of the reef rim, adjacent to the algal rubble zone (sensu Maxwell, 1968). The 23 closely spaced colonies occupied about 0.25m at a mean height of 210mn. Its very robust stem structure withstarrls the vigorous wave action in this exposed site. A.cupressina also withstands exi;x:>sure of sane six hours in each tidal cycle. 7. Ritamada Headland
Most of this study was conducted at Ritarncrla. To the south is a sweeping sarrly embayment and to the north the extensive mud flats of Kinka Creek (Fig.7.1). Offshore and beach profiles (Fig.7.2) show a beach slope of 1:40 rerlucing seawards of low water to 1:60.
Intertidally the area is one of deeply fissured and creviced rock strata, covered with a thick algal mat and a deposit of fine Fig. 7.3
Ritamada Headland
26~~ Wl. and sr 13,:; win:i and sea ( 10 kph
130° dominant( 6 l %)
san:i beac 2() kph rocks
Relationships of rock strata to dilitections of wind and sea.
Length of wind vector arrows is propart ional to the average wind speed in kph. 37 sediment, frcm extensive muds and very fine sands located frcm 500 to 1500m offshore. The dcminant (61%) direction of wind and wave is 130°,half
the waves being at least 0.8m high (Fig.7.3). The site is also exposed to wave action frcm the north-east' (26%) and frcm the east
(13%). The direction of strike (160 -340°) and the angle of dip
0 (40) of the rock strata result in the long axes of the rock masses lying obliquely to wind and wave. Colonising organisms experience either vigorous wave action on the exposed southern and eastern aspects or shelter on the western and northern faces. 8. Biology 8.1 Introduction Due to the variations in study site topography, degree of slope, fissuring and exposure to wave action, intralittoral zones occupied by organisms were related to heights above chart datum rather than to traditional biological zones. Tidal corrections related to the nearest Standard Port to Keppel Bay are available in the current Queenslarrl Tide Tables
(Department of Harbours and Marine) • The Queensland Beach Protection Authority (1980) has ?,Iblished data on tidal heights recorded at Rosslyn Bay within the study area, while data on beach and offshore profiles are available frcm both these sources. 8.2 Envirormental Tolerance 8.2.1 Exposure Aglaophenids were found in residual tide pools frcm Fig. 8, 1
Percentage exceedance distribution of water level under tidal influence.
water Keppel Bay. -water level level A.H.D. L.W.D. (~tres) (netres) ,....._ r,...
2 ~~ High Springs (1. 70) ~~an .water . 4
~ " ~ ' ~ High T"at er 'Ille (0.80) ' \ M:!an aps . 3 ' 0 \
\ ' 2 . I\ ' •-~an Lo,., ~fater ~leaps ( -0. sn) -1 ' .
?~an Low I-later Springs (-1.70)' ' r-.... ' -2 "- "' ...... r---.: 0
• 01 0.2 2 5 l 0 3 0 50 70 90 95 99 99.99%
Distribution based ori c om111ter analysis of hrurly water levels re corded at Rosslyn Bay during the four months June, September, December 1975 and !-1.arch 1976.
Note on tidal planes: A.H.D.- lustralian Height Datum L .w .D.- Low Water Datum (after Beach Procect ion /uthority) 38 the mid-littoral zone seawards. At no time were aglaophenids found exposed to the air at these mid-tide levels or at levels down to mean low water. However very low tides, briefly exposed hydroids at the lower littoral.
In July 1984 during a predicted low tide level of 0.2m below MLWS, many L.philippinus were found densely covering the substrate frcm here upwards for some 250-
300mn.
A graph of percentage exceedance of water levels under tidal influence was used to determine the exposure of hydroids at this lower level. The graph was based on computer analysis of hourly water levels recorded at
Rosslyn Bay harbour during June and September 1974,
December 1975 and March 1976 (Beach Protection Authority
1980) (Fig. 8.1). It may be seen that organisms at this level would normally be infralittoral rather than intralittoral and would only be exposed to the air some 3% of the time. Colony density was much higher than the population density some 20 rretres shoreward (that is, 0.5 metres in vertical zonation). L.philippinus appears to be sensitive to exposure to the air at levels greater than
3%. Keppel Bay tides show a diurnal height inequality during both sumner and winter months, averaging 0.3 metres. Fig. 8.2
Hour of monthly lo1o2st Low Water related to mean monthly temperature, for Keppel Bay.
co
30 22 !1 M m X .. 0 29 20 e n t 18 28 °f h 1 27 16 d y a """ y m 26 14 i e n a 25 12 n /x h 24 10 0 T u e r 23 / m 8 s p. 22 6
21 4
2() 2 19
J F M A M J J A s 0 N D Month
-x-x- Monthly mean temperature
-o-o- Time of day of lo1o2st low water, ( 24 hour cycle) Fig. 8.3
N
Wave directions
26% ' ... / ( 13 %
(; 1 %
Orientation of rock strata at Ritamada,Keppel Bay.
A;B;C;D; eite types of hydroid locations. (See text) 39
During sumner (December to March), the lowest low tides occur between lam and 4am when ambient air temperatures are coolest (Fig. 8.2). During the winter months (June to
August), the lowest low tides occur between 2pn and 4pn.
Altoough the lowest winter tides occur during daylight hours, ambient air temperatures seldom exceed 22C while sea temperatures average 18C. The result of this tidal pattern is that organisms at
the lower littoral fringe are subjected to minimal insolation, thereby lessening envirornnental stress. 8.2.2. Shelter from wave action
The degree of shelter from wave action, which supported the greatest population density of L.philippinus was assessed, four categories of shelter being defined (Fig.8.3)
Type A Easterly to south-easterly aspect or rock directly exposed to wave action.
Type B Easterly to south-easterly aspect of rock sheltered from direct wave action by the juxtaposition of other rocks.
Type C North to north-westerly aspect of rock which was directly exposed to wave action.
Type D North to north-westerly aspect of rock sheltered from direct wave action by other interposed rocks. Table 8.1 Distribution of b_.philippinus by site types at Emu Park,Keppel Bay.
(1) Mean Low Water Springs level
Site Type Number of Percentage specimens ... ''
A 0 0
B 5 8.3 C 21 35.0 D 34 56.6
Total . 60 100
(ii) Mid-tide level.
Site type Number of ' Percentage specilJ!ens
A 1 1.6 B 9 15.0 C 13 21.6 D 37 61.6
Total 60 100 40
Hydroid colonies at Mean Low Water Springs and mi~ littoral level were assigned to one of these site types
(Table 8.1).
Results: At Mean Low Water Springs, no aglaophenid colonies
were found at site type A, although very heavy
colonisation was found at types C and D (92% of total 60 specimens). At mid-littoral level, the heaviest colonisation was also at site types C and D which together supported 83% of
the 60 specimens examined. At site type B however,
colonisation rose, fran 8.3% to 15%.
Discussion: Littoral organisms are stressed by wave action which may
cause damage by abrasion with suspended particulates, by drag (creating directional forces on stem or support structures) and by turbulence, (beating the organisms
against rocks or sand): delicate hydroid colonies may be particularly disadvantaged and it is postulated that wave action is their major limiting factor. The increase in
colonisation of site type Bat mid-littoral level may therefore be due to a shoreward dissipation of wave energy.
8.2.3 Shade At 23 Q 30 I S.Lat., sunlight is intense throughout the year, even in winter (June through August). In rock pools, Fig. 8 .4
Sites of attachment of aglaophenid colonies on rocky substrates
...
rock substrate
aglaophenid colonies
rock substrate remnant of gorgonian stem. 41 aglaophenids canpletely exposed to day-long insolation, are equal in size to those inhabiting ioore shaded sites,
such as crevices or vertical rock faces. Thus sunlight itself is not a limiting factor in the distribution of local aglaophenids.
8.2.4 Spatial Orientation At Ritamada, attention was directed to the orientation of aglaophenid colonies to their substrates. (i) Most carrnonly, colonies occupy the upper edge of large, stable rocks (Fig. 8.4), typically at sane
distance above the floor of rock pools. Rarely (three colonies only) were they attached to rocks on the sandy pool floor, where a slow accumulation of fine sediment had almost covered the rock substrates. A further disadvantage of this site is the abrasion by bottom sediment, under the influence of turbulent water movement. (ii) A feature of the Ritamada area is the presence of numerous dead gorgonian stems attached to the rocky substrate below residual water levels, from
the mid-littoral zone to the infralittoral fringe. These were without exception, heavily colonised by L.philippinus. (iii) No orientation effects due to gravity were observed. Measurements of the angles at which hydroid colonies protruded fran the horizontal 42 plane (0) were made, using a large protractor. Values of +70 0 to -30 0 , with a modal value of +70 0 ,
were recorded over rocky substrates.
On gorgonian stems, which characteristically support a profuse growth of aglaophenid colonies
at mid-to lower littoral levels, specimens were found to project in a radial fashion, at random angles fran the horizontal varying fran +90°to-70~
(iv) On rocky substrates, no orientation of hydroid
colonies to water movement could be demonstrated: colonies randomly occupied all vertical planes. Grigg (1972) showed that the morphology of sea fans maximised trophic opportunities while Riedl (in Boero 1984) showed plumose hydroid colonies to
be oriented perpendicularly to the daninant direction of water movement. In the surf zone, organisms are exposed to vigorous and random water movement and the lack of orientation of hydroid colonies in this study accords with the proposals
of Riedl.
On gorgonian stems, hydroid colonies, although projecting randomly from any part of the stem surface, consistently directed the posterior aspect of their branches to the base of the gorgonian. [As the branches and hydrocladia of Fig. a.s
Attachment of branches and h}'droclad ia of L. philippirus
aspect
anterior aspect /120°~ . branch or h}'drocladium
stem posterior aspect 43
L.philippinus are displaced anteriorly on the stem, the colony has in effect a posterior and anterior aspect (Fig. 8.5)). This arrangement of hydroid growth would minimise resistance to water
flow past the colonies and reduce the risk of structural damage as the gorgonian stem was bent to and fro by water movement.
8.3 Substrate (i) The rock formations of Keppel Bay are predominantly quartz greywacke and mudstone (Kirkegaard et al.1970), both on the mainland and also the offshore islands. The strike of the rock strata is generally north north-west, with a dip of 40° in a direction 060° (op.cit.). The direction of strike was confirmed by compass bearings at the study sites, the dip value also agreeing with visual assessnents made in the field. This rock alignment significantly affects hydroid distribution. The combination of north-west
rock alignment and south-east wind and waves, results in exposed southern and eastern rock faces and relatively sheltered northern and western aspects. A difference in colonisation densities between sheltered and exposed rock faces can be demonstrated (Sect.
8.2.2).
0 . The 40 dip in the rock strata produces considerable fissuring and crevicing, resulting in 44 nLJnerous residual tidal pools and sheltered sites being available. (ii) All rocky areas at the mainland study sites were covered with an unanalysed "thick algal mat" at least
2rrm in thickness (sensu Stephenson 1961). Off-shore reserves of fine sediments can produce turbid inshore
waters and impregnate the algal mat with silt.
(iii) L.philippinus and A.cupressina were found on a calcareous substrate encrusted with coralline algae at
North-West Island. Colonies of these two species were found respectively in the interstices of cll.lnps of
staghorn coral (Acropora ~) and on the massive consolidated reef rim. A dead fragment of staghorn coral, recovered fran the Fitzroy River estuary, was found to support a
colony of L.phoeniceus. (iv) Aquaril.ln specimens of L.philippinus when reproducing by stolonisation (Sect 8.2.3), adhered to the glass walls of the aquaril.ln, and elongated successfully for
two to three weeks.
(v) Especially at lower littoral levels, aglaophenid hydroids profusely colonised attached rannants of gorgonian stans. (vi) At both Ritana:la and Pumpkin Island study sites, extensive areas of brown algae were found on the seaward rockfaces; no aglaophenids occurred at either site. Fig. 8.6
D- seconi order branch (20). order branch (1°)
A-stolon
(F:) hydranth on hydrocladia (E)
schene of aglaophenid branching A stolon B main stem C first order lranch ( 1 °) D second crder branch (2°) E h}drocladium or third order branch(3°) F h}dranth Table 8.2
Length of main stem of !:.-philippinus in relation to degree of branching . . . Degree of branching X Range n
Main stem only 16.2mm upper limit 58 45mm 1° branching 43.3mm 13-70mm 75
2° branching 61.6mm 27-118rnm 68
' 45
Absence of colonisation may be either because brown
algae may be inimicable to larval settlement, or
because wave action may destroy newly settled hydroids. With this local exception aglaophenid hydroids successfully establish thanselves on a wide
variety of substrates. 8.4 Growth
8.4.1 Colony growth and branching Aglaophenid growth habit is monopodial with terminal growing points. Typically aglaophenid colonies have two orders of branching; the second order branches then support hydracladia which in turn bear the hydranths (Fig. 8.6). Growth estimations using extractive procedures such as dry weight or ash were deaned impracticable and unrewarding, so measurements of colony main stem and the longest first and second degree branches (if present), were adopted to provide estimations of colony growth and maturity. Specimens witoout branching other than hydrocladia were classified as juvenile. L.philippinus exhibits extremely variable branching (Table 8.2). Juvenile (unbranched) colonies showed a mean length of 16.2nm (n=58) with a Standard Deviation of 7.0 (Appendix I). Specimens showing similarly variable first degree branching, had a mean main stem length of
43.3nm (range 13 to 70mn; n=75). No relationship could be determined between the occurrence of branching and main 46
stem height (r=.255). Specimens with two degrees of branching showed equally variable branching (Appendix II), no positive correlation being evident between main stem
height and appearance of first or second degree branches (r=.25;n=68). The mean main stem height was 61.lmn (range
27 to 118mn), mean length of first order branches was 25.4mn (range 9 to 62nm) while second order branches
attained a mean length of 9.Srnn (range 3 to 24mn) (Table
8. 2). Branching of local L.philippinus is independent of main and secondary stem lengths.
8.4.2. Stolons Colonies of L.philippinus on small fragments of rock were transferred to a dark aerated aquarium maintained at
21C. In fourteen days, regression of the algal mat covering the rock exposed the hydroid stolons. In each of the fifteen samples examined, several distinct vertical
stems supporting normal branched colonies arose sequentially from a highly convoluted and anastanosed stolonal network. The maximum distance between vertical
stems in the series examined was 60mn, while the maximum dimensions of the stolonal mats reached 143mn x 23rnn. Whilst fortuitous anastanosis of stolons from different parent colonies cannot be eliminated in this short series of observations, the regular occurrence of linearly arising clusters of L.philippinus colonies 47
indicates that vegetative reproduction is a comnon and important feature of this species.
8.4.3. Regression Several intact colonies of L.philippinus were placed in an aquarium exposed to ambient lighting coooitions and
maintained at 21 C. Viability was confirmed by observation of capturing movements of the hydranth tentacles and also by the presence of peristaltic
movements in the coenosarcal cavity; however no attempt was made to provide a food source. Regression of distal hydranths on random hydrocladia
began within seventy-two hours and regression of all hydranths appeared canplete within five days. Subsequent shedding or resorption of hydrothecal material resulted in
bare stems and hydrocladia, which in turn rapidly thinned
as perisarcal material was absorbed. Section 8.5.2 deals with the subsequent regeneration of these specimens
by stolonisation.
8.5 Reproduction of aglaophenid hydroids
8.5.1 Within Australian waters, reproductive data on
aglaophenids are rare. Shepherd and Watson (1970) have recorded fertile sublittoral aglaophenids in South Australia fran August to November, although none of those species described have been found in the study area. This fiooing agrees with Moore (1972): organisms ranging into cooler waters breed fran winter to early sumner. Table B. 3 ·
Spee ies Month
J F M A M J J A s 0 N D
L. phi lippinus # fl - I L. phoeniceus #
* A. cupress ina
T.angulosus fl
* .!!-~ians.
Records of fertile colonies 1 ftom the litera~ure,of those
species of aglaophenid hydroid found in Keppel Bay •
fl Fertile colonies reported
* No available temporal record 48
Within Queensland, fertile colonies of L.phoeniceus and T.angulosus have been recorded fran Low Isles, North
Queensland by Briggs and Gardner (1931) during May.
In South Africa (Lat.30 0 S), Millard (1975) reported fertile L.philippinus in July. In Madagascar (circa
0 Lat.20 S), Gravier (1970) described the simultaneous release of medusoids from all colonies in August.
Subsequently no remaining phylactocarps were to be found on the colonies, being apparently discarded when spent. Fertile colonies of L.philippinus have not been found within Keppel Bay either during the present study or in
its single previous recorded occurrence (1950, in Pennycuick 1959). This species is pantropical, between 35° North and 35° South Latitudes. Moore (1972) comnents that
species restricted to the tropics tend to centre their breeding in the late sumner and early autumn. Records of fertile colonies in tropical waters of the Southern Hemisphere are shown in Table 8.3.
No data are available on the time taken by gravid colonies to mature and release gametes nor on the time
that gametes or larvae spend in the plankton. Table 8.3 suggests that settlement and attachnent of larvae and the subsequent developnent of feeding zooids may coincide with the spring plankton bloom of September or October. B.5.2 Regeneration and Stolonisation Colonies of L.philippinus remaining in the aquarium 49 after the observations on regression (Sect. 8.4.3) were
canpleted, had distal extremities of branches in contact
with the aquarium walls elongating at 5.Smn per day (mean;
n=ll). One colony then became detached leaving the
growing branches adherent to the walls. The branches of
this colony began to grow fran the proximal ends whilst
maintaining distal growth, albeit at a reduced rate for
both extremities of l.8mn per day.
No published figures for aglaophenid growth rates are
available, although Lenhoff Muscatine and Davis (1971)
record growth rates for non-aglaophenid species, of 1 to
10mn per day, different growth rates being shown for
stolons, stems and lateral branches.
The present study indicates that L.philippinus has a higher capacity for regeneration and plasticity than expected. Stolonisation may also be a significant means
of vegetative reproduction intralittorally, where
conditions for sexual reproduction appear neither satisfactory nor predictable.
8.5.3. Discussion As no fertile colonies of L.philippinus have yet been found intralittorally in Keppel Bay, several reasons may
be considered, namely:
(i) Developnent, maturation and shedding of gonangia
may have occurred briefly between subsequent visits to the study site. This is unlikely in 50 view of the lefl3th of the study and the regularity of surveys at two to three weekly intervals. (ii) Mortality may be so high that few specimens reach sexual maturity, the population turn-over time being shorter than the reproductive life cycle. (iii) Envirornnental stress within the littoral zone may permit only vegetative reproduction or stolonisation, sexual reproduction being restricted to the infralittoral zone, fran which recolonisation is possible. Factors influencing gametogenesis may include tanperature, size, age and density of the colony, stagnation and nutrition. Extrenes of tanperature occur intralittorally and probably preclude the use of tanperature as an envirormental cue for gametogenesis: they could also have adverse effects on developnent of gametes and embryos. Colony size does not vary significantly fran lower to midlittoral levels, while colony density is irrelevant in this sparsely settled littoral zone. Longevity records for marine hydroids are few: perhaps hydranths are short-lived while the coenosarc is long-lived and produces hydranths under favourable coooition. Life spans recorded range fran one month for Obelia longissima (MacGinitie and MacGinitie
1968) to over two years for Sertularia cupressina (Cornelius 1985 pers. comn). Reproduction canpetes poorly 51 with sanatic processes when food supplies are poor, gonangial production being suppressed in favour of processes such as stolon tip growth (Campbell 1974;
Stearns 1976). The work of Allen and Ferguson Wood (1950) has shown L.philippinus to be one of the most regular and prolific colonisers of sample fouling plates in Moreton Bay (28°S), from which circumstance, the presence might be inferred of an effective offshore reservoir of breeding colonies. The very heavy colonisation found in the infralittoral fringe of Keppel Bay indicates that a similar situation may pertain. The regular presence of an interconnecting stolonal network between proximate colonies within clumps of L.philippinus suggests that adventitious larvae having settled initially at a "tolerable" intralittoral site, vegetative reproduction then results in an ostensibly gregarious growth habit. Fig. 8. 7
Nematophores and discharged nematocysts of !!-philippinus
a. retracted nematopohores with nematocysts in situ b. retracted hydranth c. hydrotheca d. abcauline intrathecal ridge e. discharged microbasic mastigophore
(Keppel Bay specimen) 52 8.6 Nematocysts and stinging potential
The definitive work on nematocysts is that of Weill (1934) based on the morphology of the discharged threads and shafts. His classification has been widely accepted and is adopted here.
8.6.1 Nematocysts of L.philippinus and L.phoeniceus fran Keppel Bay have been examined by light microscopy (Fig.
8.7) at intervals during the year to determine if any seasonal variation existed in nematocyst concentration. Method:
A detached portion of a living specimen of
L.philippinus was suspended in sea water on a microscope slide and stimulated with a minute piece of fresh prawn on a dissecting needle. This physico-chernical stimulation
gave a more profuse discharge of nematocysts fran nanatophores than mechanical stimulation alone.
Additional portions were suspended in sea water and anaesthetised by the gradual a&3ition of magnesium sulphate solution until narcosis and relaxation were canplete. Results: Tentacular protrusion was readily achieved by narcosis whilst protrusion of nanatophores exposed their intact nematocysts. Sane irregular and unpredictable discharge of nanatocysts was found from nematophores with these techniques. In both species examined, microbasic Fig. 8.8
Ne mat ocysts of _!!. phi lippinus
a. median nematophore b. undischar ged nematocys ts-microbasic mastigophores c. dis charged nematacysts-microbasic mast igophores d. lateral nem8:tophore e. h:yd ranth tentacle f. discharged atr ichous isorhizas g. h:ydranth cavity Fig. 8 ;9'
Tentacular nematocysts (atrichous isorhizas) of~- philippinus
e
a. protruding. microbasic mast igophore:; b. h)'dranth tentacles with atrichous isorhizas in situ c. nemat otheca d. h)'drotheca e. discharged atrichous isorhizas.
1-philippinus TCirchenpauer, 1872 (Keppel Bay) 53 p-mastigophores were the only nematocysts found in the nematophores. Specimens of L.philippinus regularly contained eight nernatocysts in uooischarged nematophores.
No seasonal variation was found. Lenhoff and Loanis (1961) recorded that when cell division occurred in a maturing cnidoblast, eight or sixteen nematocysts were regularly formed. The only other accessible data was that of Vervoort (1946) who reported three to seven nematocysts in nematophores of L.philippinus from the East Irrlies. Discharge of nematocysts fran the tentacles unlike that from the nernatophores of L.philippinus by the previous method failed, so an alternative procedure was adopted. (Due to scarcity of specimens, L.philippinus was the only species tested) •
Method: A specimen was placed on a microscope slide, water removed with a piece of filter paper, the slide flooded with distilled water for 20 seconds and methylene blue solution added briefly. Liquid was then removed by filter paper applied at the edge of the specimen. Results:
By using this technique, a predictable discharge of nematocysts was achieved from both nematophores and hydranth tentacles (Fig. 8.8), nematocysts fran the latter being exclusively atricoous isorhizas (glutinants) (Fig. 8. 9) • 54 Not all nernatocyst types respond equally to all types of stimuli, Lenhoff and Loomis (1961) reporting atrichs to be
inhibited by foodstuffs and stimulated by contact with
smooth surfaces.
8.6.2 The stinging potential of L.philippinus is well doc\.lilented in the literature (p.l), the presence of
microbasic mastigophores indicating this potential.In the present study an assessment of stinging ability has been
made and evidence sought of a seaonality in stinging
potential. Method:
At monthly intervals during 1983, in situ specimens
of similar size were drawn briefly and firmly over the dorsal aspect of the interdigital finger webs, this area
of skin providing a more responsive target than the thicker palmar aspect. Symptoms of pruritus or prickling were recorded together with any physical signs such as
erythema, urticaria or vesiculation (Appendix III). A
graduated scale of stinging intensity was developed to afford some measure of quantitative assessment.
Type 1. Very mild pruri tus or prickling; comnonly delayed for two or more minutes; no erythema or urticaria; duration of effect less than ten minutes.
Type 2. Mild pruritus and prickling; ccmnonly delayed for up to two minutes; faint erytherna; 55 sane diffuse and non-confluent urticaria;
duration of effect up to thirty minutes; symptans usually intermittent.
Type 3. Moderate pruritus and prickling sensations; comnonly delayed up to one minute; distinct confluent zones of erytherna; urticarial wheals 1 to 2mn in diameter; sparse vesiculation;
symptans intermittent over a period of one hour. Type 4. Moderate pruritus and sharp stinging discanfort; usually irnnediate or delayed at most for a few
seconds; wide zone of confluent erythematous and urticarial lesions; multiple small vesicles of l-2rnn diameter; symptans may persist intermittently for up to twenty-four hours;
overt skin lesions disappear within six hours. Results: A mild and temporary discanfort could be elicited during most of the year, whilst more intense effects were found fran October to March. Characteristically, hydroid stings are delayed rather than imnediate in effect, such delay being more apparent in the milder winter stingings, whilst the sharper stingings of sumner months achieved maximun intensity more rapidly. Assessments of stinging potential on the graduated scale of 1 to 4 were plotted and combined with a curve for monthly sea temperature. A positive relationship between Fig. 8.10
Keppe 1 Bay monthly sea temperature and aglaophenid stinging potential
...
30
29
28
27
26
25 4
0 t.) 24
Q) 23 B"" 3 .... ea ea ."4J ""Q) i:: ~ 22 Q) 4J ~ 0 21 Cl- 2 00 i:: ."00 20 i:: ."4J Cl) 19
18
J F M A M J J A s 0 N D Mnn~ ... 56 ambient water temperature and stinging potential was suggested (Fig. 8.10). As the size of the each colony used in the tests was chosen to minimise the variation in the number of nanatocysts applied per unit area of skin, two hypotheses for the seasonal variation in stinging potential are: (i) the developnent of interstitial cells into
cnidoblasts and their subsequent maturation into nanatocysts may be influenced by seasonal envirormental conditions; (ii) thresholds for stimulation and effective discharge of nematocysts may fluctuate seasonally. The number of nematocysts present in an undischarged nematophore ranains constant during the year (Sect. 8.8.1) and the first hypothesis is therefore unacceptable. A fall in water tanperature raises the threshold for nanatocyst discharge (Rees,1966). Correlation between Keppel Bay temperature and seasonal stinging potential (Fig. 8.10) suggests that a seasonal rise in temperature above 23C may critically lower the threshold for discharge. The colonies of L.phoeniceus found during surveys of the Emu Park study site in May and October 1983 were also tested for stinging potential in the field, altoough due to shortage of specimens no formal testing was done. The colony found in May caused a sting of Type 2 while two 57 colonies in October produced Type 3. The results thus resemble those of L.philippinus. 58
COOCLUSION
The upper littoral limits of sedentary marine organisns are influenced by physical factors which show a much greater range of values in Keppel Bay than in the open sea. Salinity values fran Heron Island are stable (35.15%0 to 35.65%0), whereas Keppel Bay values range fran 27%0 to 42%0 due to: a limited advective exchange of water
(especially with southerly or westerly winds); the combined evaporative effect of high insolation in proximity to a land mass and an average wind speed of 20kph;the high seasonal input of river water. Prolonged exposure to these fluctuating salinity levels does not appear to have any direct effect on the occurrence or distribution of aglaophenid hydroids within Keppel Bay. Inshore water temperatures in Keppel Bay range fran 19.lC to 29.3C a much wider spectrum than those of Heron Island. The temporal distribution of maximum and minimum sea and air temperatures in Keppel Bay shows a close relationship, reflecting the proximity to land, whereas at Heron Island a time lag of one month is evident. The difficulty in developing an accurate correlation between local air and infralittoral sea temperatures serves to emphasise the erratic values to which intralittoral organisns may be subjected. In view of the pantropical distribution of Keppel Bay aglaophenids, it is not considered that water temperature has any limiting effect on the recruitment and settlement of local hydroid larvae nor on littoral processes of vegetative reproduction. 59 The 100st critical factor in hydroid distribution intralittorally is considered to be exposure to air, as no specimens have been found above residual water levels, except when a water level below Mean LOw Water Springs, (which occurs 3% of the time), exposes a profuse growth of L.philippinus. Neither L.philippinus nor L.phoeniceus have been found above midlittoral level. Vigorous wave action is considered to be the second major factor influencing distribution of L.philippinus. At all littoral levels, colonisation is heavier on the more sheltered western and northern aspects of rocks than on the more exposed eastern and southern flanks.
Colonisation on the exposed aspects does however increase slightly fran lower to midlittoral level, corresponding with a decrease in wave energy shorewards from low water. Areas exposed to unhindered wave action such as the reef rim of North-West Island and the seaward side of Pumpkin Island ccmpletely lack colonisation by L.philippinus. Sediment, except at extreme levels, shows little effect either on density of settlement or on colony growth, as mean colony heights are similar over littoral gradients of sediment deposit both at Emu Park and Ritarnada. It is considered fran field observation alone, that neither phototactic nor geotactic response govern larval settlement. Colonies of L.philippinus occur on a wide range of geological and biological substrates, although none were found on brown algae on the exposed aspect of rocks at Pumpkin Island arrl Ritarnada. Favoured colonisation sites were the upper edges of rock formations and the protruding remnants of gorgonian stans. Both sites are elevated above the floor of tidal pools and afford maximun trophic opportunity by 60 giving unhindered access to particle-laden currents, whilst minimising the deposit of sediment on the colonies. No consistent orientation of hydroid colonies could be detennined as the intertidal zone lacks a daninant direction of water movement. However those specimens colonising gorgonian stans were consistently found to have their posterior aspect directed to the base of the gorgonian, thus minimising water resistance during wave surges and also making the most efficient and conservative use of space. Trophic opportunities show a seasonal increase with the spring plankton bloan. In addition, sessile animals may also benefit from the constant presence in the water of organic detritus. The sediment present at all mainland study sites is predominantly flocculated silt from land drainage into Keppel Bay and may provide a significant proportion of the trophic resources of hydroid colonies. Fertile colonies of L.philippinus have not been found littorally within Keppel Bay. This pantropical species occurs as far south as
Moreton Bay as a prolific coloniser of sample fouling plates. This argues an adequate offshore breeding stock with the capacity for constant larval recruitment to inshore substrates. The capacity of
L.philippinus for vegetative reproduction is indicated by the rapid initiation and maintenance of stolonisation in vitro and also by the regular and profuse production of multiple erect colonies from a persistent stolonal mat in vivo. It is considered that the patchiness of intralittoral distribution is not due to gregariousness of larval settlement but rather to the settlement of larvae on a topographically canplex substrate followed by the secondary vegetative reproduction of 61 these colonies. The relative contributions of offshore recruitment
and vegetative growth of the persistent stolonal mat are not known.
Both L.philippinus and L.phoeniceus can inflict mild to acute stings, which are characteristically delayed rather than imnediate in
effect. Stings vary seasonally in intensity, reaching a maximun during the late sumner to early autunn. Microscopic examination at intervals throughout a year showed the number of microbasic mastigophores (the nanatocyst responsible for hunan injury) to remain constant at eight, with each intact nanatophore. The variation in virulence is therefore attributed to an alteration in the threshold
for nematocyst discharge. Increases in ambient water temperature above 23C appear to achieve this. 62
ACKNCMLE[x;EMENTS
During the course of this study, I have becane indebted to a number of people without whose support the task would have proved much more difficult. I am firstly indebted to my mentors, Ors Rothwell, MacIntyre and Newby: Dr B Rothwell, Deputy Principal of Mitchell College of
Advanced F.ducation and formerly Head of Biology, Capricornia
Institute of Advanced F.ducation for acting as External Supervisor, for initiating and co-ordinating the academic
aspects of the prograrrme with the University of New South Wales and for his support, encouragement and sound advice during the
preparation of the project;
Dr R J MacIntyre, Senior Lecturer in the School of Zoology,
University of New South Wales, for acting as Internal Supervisor, for his encouragement and careful guidance through
the academic aspects of the programne and his wealth of sound advice on the presentation of the thesis; Dr R Newby, School of Biology, Capricornia Institute of
Advanced F.ducation, for many useful and stimulating discussions
during the developnent of the research programne, for his most canpetent professional support and helpful suggestions during
the canpilation of the thesis.
I am particularly indebted to Mrs M wastell for her painstaking typing of the manuscript and her meticulous skill in transforming the draft
into proper format. My thanks are also due to Sr Veronica Mary, 63
Aaninistrator of the Mater Hospital, Rockhampton for her courtesy and kindness in granting the use of hospital word processing and printing facilities, and to Mr KC Gillam for his canpetence and time in checking the proofs. 64
ACKN Allen, R J Geological Survey of Qld for sedimentation data Amess, J Librarian, Australian Institute of Marine Science for scientific references. Baker, Dr J James Cook University for references in marine pharmacology. Beeston, C Ritarnada for his valuable assistance with the collection of water samples. Bruce, A J Heron Island Research Station - for comnents on Heron Island hydroids. Burdon-Jones, Prof. C James Cook University for comnents on scientific references. Cannon, Dr L Curator of Lower Invertebrates, Queensland Museum for his courtesy·in providing copies of scientific papers and information on the Museum hydroid collection. Cooke, Dr W University of Hawaii for comments and provision of his paper on Hawaiian hydroid species. Cornelius, Dr P British Museum (Natural History) - for generously forwarding copies of his papers and for advice and personal assistance rendered during visits to the Museum. C S I R 0 for provision of hydrological data fran Heron Island. 65 Endean, Dr R University of Queensland for his helpful cooments and courtesy in providing copies of papers on nernatocysts and toxicology. Gold, Dr MR Consultant dermatologist for helpful advice on dermatological aspects. Harrison, P James Cook University for ccmnents and provision of a research paper on coral spawning. Kenny, Assoc.Prof. R James Cook Univeristy for access to Dept of Marine Biology and courtesies extended while visiting the University. Librarian Staff Capricornia Institute of Advancerl Education for courtesy and efficiency in obtaining reference material. Miller, Dr M University of Auckland for advice on topics of cnidarian biology, and scientific papers. Morrison, N National Library of Australia for Biosis database search. Patterson, D Beach Protection Authority for Capricorn .Coast beach profiles. Pennycuick, Dr P CSIRO for advice and information on aglaophenid occurrence; for very generously providing copies of early papers on Australian Hydroids by Bale; and for supplying a copy of "Faunistic Records frcm Queensland". 66 Prowse, I Yeppoon, for providing a specimen of T.angulosus and habitat data. Roberts, E Librarian, Marine Biological Association of the United Kingdom for information on overseas reference sources. Southcott, Dr RV South Australia, for advice on marine toxicological references. Varley, A Marine Biological Association (United Kingdan) for a copy of a paper on L.nuttingi. Watson, J Marine Ecology, Victoria, for encouragement, advice and for provision of a copy of her paper on sublittoral hydroid substrates in South Australia. 67 REFERENCES Allen, F.E. and Ferguson Investigaton on underwater fouling II; Wood, E.J.,1950 The biology of fouling in Australia; results of a year's research. 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Marine and Brackish Water Hydroids. Dept.zool.Univ.Qld •.!_(69:141-210) 75 Perkins, E.J.,1974 The biology of estuaries and coastal waters Academic Press, London:6-155. Pickard, G.L.,Donguy, A review of the physical oceanography of J.R., Henin, c., the Great Barrier Reef and Western Coral Rougerie, F.,1977 Sea. Australian Institue of Marine Science Monograph Series.~. Pyefinch, K.A. and Notes on the general biology of Downing, F.S.,1949 Tubularia larynx, Ellis and Solander. J.Mar.Biol.Assoc.U.K.28:21-43 Ralph, P.M.,1956 Variation in Obelia geniculata (Linn.1758) an:1 Silicularia bilabiata (Coughtrey 1875) Trans.Roy.Soc.New Zealand 84(2): 279-296. Ralph, P.M.,1957 New Zealan:1 Thecate Hydroids Part I: campanulariidae and Companulinidae. Trans. Roy.Soc.New Zealand 84(4): 811-854 Ralph,P.M.,1958 New Zealan:1 Thecate Hydroids Part II Lafoeidae, Lineolariidae, Haleciidae and Syntheciidae. 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Vervoort, W., 1946 Exotic hydroids in the collection of the Rijkmuseum van Naturlijke Historie and the Zoological Museum of Amsterdam. Zoologische mededeelingen XXVI: 287-351 Vervoort,W.,1968 Report on a collection of Hydroida fran the Caribbean Region, including an annotated checklist of Caribbean hydro ids. Zoologischke Verhandelingen Uitgygeven Doorhet van Naturlijke Historie te herden.92:1-124 Watson, J.E.,1973 Pearson Islam Expedition 1969. Part 9:Hydroids. Trans.R.Soc.S.Aust.97(3):153-200 Watson, J.E.,1975 Hydroids of Bruny Island, Southern Tasmania. Trans.R.Soc.S.Aust.99(4):157-176 79 Watson, J.E.,1978 New species and new records of Australian athecate hydroids. R.Soc.Victoria Proc. 90(1-2): 301-314. Weill,R.1934 Contribution a l'etude des cnidaires et de leurs nematocystes. Trav.Sta.Zool.Wimereux.10(11):1-701 Werner, B.1963 Effect of sane enviromental factors in differentiation and determination in marine Hydrozoa, with a note on their evolutionary significance. Ann.N.Y.Acad.Sci.105(8):461-488. 80 APPENDIX I Lytocarpus philippinus Lengths of main stem and longest first order branch in specimens bearing only first order branches. Main Stem Branch "XII 11y II IIX" "Y II "X" "Y" ------40 10 21 6 23 12 25 15 18 8 22 9 70 13 13 5 44 17 67 11 23 14 19 7 54 14 20 11 27 9 33 11 31 10 35 6 21 7 29 7 68 18 33 14 21 11 43 12 23 15 20 8 48 27 37 9 28 11 32 8 32 12 30 21 29 14 32 7 28 8 23 17 20 5 33 12 43 18 50 10 23 7 20 9 15 5 37 12 27 8 31 11 31 16 41 18 22 7 25 6 56 22 27 10 43 20 37 11 33 16 33 11 68 13 30 9 35 15 28 14 27 7 30 9 43 18 29 11 24 7 22 11 24 9 29 14 42 21 40 12 32 11 31 9 28 9 22 17 15 13 n = 75 X = 11.01 X = 43.27 y = .016 y = 11.69 r.= .255 81 APPENDIX II Lytocarpus philippinus Length of main stem, longest first and second order branches in specimens bearing two orders of branching. Mainstem = "X" ,. First order branch "Y" Second order branch= "Z" X y z X y z 45 40 10 43 11 5 50 23 8 73 25 7 45 15 7 94 27 8 100 40 6 42 25 19 40 20 4 118 36 17 75 25 13 38 18 7 60 17 10 33 27 11 65 18 12 77 48 11 75 25 11 82 38 24 85 35 10 81 37 17 80 25 10 52 37 12 80 20 6 81 54 11 55 23 8 69 42 7 40 15 11 83 62 7 63 32 8 54 23 12 40 20 6 77 28 19 28 15 7 66 13 5 32 21 12 37 15 8 38 16 6 30 11 7 27 11 4 37 19 7 45 13 4 68 14 7 45 23 3 62 18 6 53 30 8 115 32 12 61 28 8 77 32 9 61 33 14 73 22 7 72 16 8 110 21 16 97 24 7 52 21 6 40 20 6 43 22 11 22 14 6 73 26 7 58 28 11 26 15 9 81 27 9 100 33 22 47 26 7 60 33 18 28 9 4 78 50 18 65 35 12 X = 61.1 n = 68 y = 25.4 r = .25 z = 9.5 82 APPENDIX III Definition of clinical terms used in Section 8.6 Erythana: Active dilatation of cutaneous blood vessels, usually arteriolar as well as capillary, so that the margin of the lesion teoos to be ill-defined aoo merge into the surrotmding unaffected skin. Pruritus: Itching, which may occur in the absence of any discernible skin lesion. Urticaria: Raised wheal, usually red (but may be skin-coloured or even pale, caused by the "triple response". May have a whitish centre and fades in a flare into the surrouooing skin. Vesicle: A pinhead-sized elevation in the skin containing fluid. An intradermal lesion (but may be intra-epidermal, when it is extremely fragile). By convention this term is given to lesions less than Smn diameter. APPENDIX IV T11hle of Salinity ~alue ■ in Keppel Bay, 'February, 1q82 to Jure,1984, Date Salinity Date SAiinity 21.2.82 42 17.7.83 34 21.3.82 40 6.8.83 34 4.4.82 40 1.9 .83 40 18.4.82 42 .. 4.10.83 36 3.5.82 42 · 23.10.83 no data 30.5.82 36 f# cyclonic rain 20.11.83 37 in N and OP.ntral 14.6.82 36 Qld. 1().7.82 36 6. 1.84 38 :?4. 7 .82 37 2.2.84 35 8.8.82 37 18.2.84 32 29.8.82 38 10.3 .84 37 12.9.82 41 24 .3 .84 38 26.9.82 39 8.4.84 35 3.10.82 no data 29.4.84 37 8. 10.82 41 13.5.84 37 :?2. 10.82 42 ' 27.5.84 37 5.11.82 39 10,6.84 37 20.11.82 39 24 .6.84 37 5. 1.83 38 30.1.83 37 16.2.83 38 2.3.83 35 1 .4. S 3 35 27.4,83 34 8. 5.83 27 #heavy local 122nm on 28,4,83 22. 5.83 37 rain, 4. 6 .83 22 I heavy loca 1 21.6. 83 35 rain,.362rmn ,29/30/5/84. H.6.83 34 Table A , OVERLYING SEDIMENT STATUE BAY Overlying sediment samples at 20 m. intervals from MLW to MHWN (upper limit of rock strata). (i) 61.2g. sediment overlying 40cm2 = l.53g.cm-2 (ii) 74.6g " = l.86g.cm-2 (iii) 59.3g " = l.48g.cm-2 (iv) 48.Sg " .. • = l .22g.cm-2 -2 Mean: l.52g.cm EMU PARK Overlying sediment samples at 10m. intervals from MLW to midlittoral (upper limit of hydroid occurrence) 2 -2 (i) 42.lg sediment overlying 40cm = l.OSg.cm -2 (ii) 28.Sg ·" = 0.7lg.cm -2 (111) 28.Sg " = 0.7lg.cm -2 (iv) 26.3g .. = 0.66g.cm -2 Mean: 0.78g.cm ' RITAMADA Overlying sediment samples at 10m. intervals from MLW to midlittoral (upper limit of hydroid occurrence). 2 -2 (i) 26.3g sediment overlying 40cm = 0.65g.cm , -2 (ii) 24.9g .. = 0.62g.cm -2 (iii) 18.6g .. = 0.46g.cm -2 (iv) 21.7g .. .. 0.54g.cm -2 Mean: 0.57g.cm Expected page number is not in the original print copy. 84 APPENDIX V No data on present sedimentation rates are available and no such work has been carried out by the Beach Protection Authority (Allan, Geol. Survey, pers.carm. 1982). To canpare study sites, samples of overlying sediment were taken fran Statue Bay, Emu Park main beach arrl Ritamada. Sediment was removed fran a rectangular perspex frame enclosing 40an on the upper surface of a flat rock and the material weighed. Samples were removed at regular intervals either fran Mean Low Water to Mean High Water Neaps along a representative traverse line (Statue Bay), or alternatively fran Mean Low Water to the upper limit of hydroid occurrence at approximately mid-tide level (Emu· Park and Ritamada). Statue Bay was entirely covered by a very heavy deposit of sediment due to the relatively flat profile and its position in the lee of a major headland. Intermittent harbour dredging since 1975 and the northwards transport of sediment due to prevailing wims and currents have probably crlded to the sediment load. Interaction of south-east and easterly wave fronts which have been refracted around the offshore islands also has an influence in depositing and reworking fine sediments imnediately offshore (Table A).