Table Of ContentINNOVATIVE NEW METHODS FOR MEASURING THE NATURAL DYNAMICS OF
SOME STRUCTURALLY DOMINANT TROPICAL SPONGES AND OTHER SESSILE
FAUNA
C.R. PITCHER, T.J. WASSENBERG, G.P, SMITH, M. CAPPO, J.N.A. HOOPER AND P.J. DOHERTY
Pitcher,C.R.,Wassenberg,T.J.,Smith,G.P.,Cappo,M.,Hooper,J.NA.&Doherty,PJ. 1999
06 30: Innovative new methods for measuring the natural dynamics ofsome structurally
dominanttropicalspongesandothersessilefauna. MemoirsoftheQueenslandMuseum44:
479-484. Brisbane. ISSN 0079-8835.
Population dynamics (growth, mortality, recruitment, and reproduction) of large sessile
fauna (including sponges, gorgonians, and corals), that dominate and provide structure on
patches ofseabed habitat in open shelfwaters, 20-50m depth, is currently under study at
several sitesintheGreatBarrierReefregion.Sites,chosentocontainrepresentativebenthos
habitatfauna,arebeingsurveyedusinganROVtodocumentdynamics,including:mapping
the large sessile fauna at each site; tagging a size range ofindividuals ofeach ofseveral
dominant species; measuring growth and mortality rates through time; observing the
occurrence ofnew small individuals for measurements ofrecruitment; taking samples to
confirm taxonomy and for histological examination in the laboratory to determine
reproductivestrategies.Bytaggingafull size-rangeofindividualsofeachstudyspecies,we
aim to estimate lifetime growth curves in three years. From these data we will construct
modelsofthepopulationdynamicsofsessilefauna, whichcan be used toestimatehow fast
the seabed habitat might recover in new reserve areas. This study will also document the
D
usage of living seabed habitat by key fish species. Pori/era, sessile fauna, dynamics,
growth, mortality, recruitment, ROV. video, tagging.
C.R. Pitcher(emailroland.pitcher{a.marine.csiro.au), T.J. Wassenberg, G.P.Smith, CSIRO
Marine Research, POBox 120, Cleveland, Qld. 4163; M. Cappo, PJ. Doherty. Australian
Institute ofMarine Science, PMB No 3, Tawnsville MC, Qld. 4810; J.N.A. Hooper,
QueenslandMuseum, POBox3300, SouthBrisbane, Old. 4J01, Australia; 26 May 1999.
Communities oflarge sessile epibenthic fauna ofeffective refuges for fisheries habitat and the
(such as sponges, gorgonians, alcyonarians and stocks and biodiversity they support. To achieve
corals), provide structural complexity to the these goals, it is first necessary to obtain
seabed - an importantcomponent ofhabitat fora information on the recover}' rates ofhabitat and
myriad ofother species - and also contribute to theprocessesthatlinktrawledareasandrefuges,
the biodiversity ofthe marine environment (Van Estimation ofrecovery rates requires inform-
DoIahetaL, 1987;Hutchings, 1990;Pitcher, 1997). ation on population dynamics, but these are
Further, they form the basis of*bioprospecting' to virtually unknown for large sessile epibenthic
discover natural products of pharmaceutical fauna (Hutchings, 1990). We are investigating
promise (Hooper et al., 1998). However, mega- the fundamental population dynamics
benthos communities are vulnerable to damage by (recruitment, growth, mortality, reproduction) of
sedimentation,dredgingandextensivetrawlingon structurallydominantmegabenthoshabitatfauna
anddocumentingtherelationshipbetweenbenth.c
the seaAbed (Pitcher et al., 1997; Sainsbury et al., ¥>*<* and ecologies usage by some commer-
1997). recentlycompletedproject(Poineretal.,
«"y ™P«rtant finfish spec.es.
998)hasdemonstratedthesignificanceofimpacts
1
ofprawntrawling on tropical seabed habitats. One MATERIALS AND METHODS
method ofmanaging these impacts for ecological
sustainabilitywillbespatialclosures(Sainsbury et STUDYAREA. SeabedareaslocatedintheGreat
al., 1997),e.g.establishingrefugeareastopreserve Barrier Reef off Townsville, Australia, were
representative seabed habitats. Predicting the surveyed forsuitable study sites in August 1997,
response ofmegabenthos to the establishment of during a voyage ofthe AIMS vessel RV 'Lady
refuge areas, and acquiring an understanding of Basten\Towedvideocameraswereusedingrided
the ecological interactions between trawled and surveysoffourareas, each about4,000km2 in the
,
refugeareas,arebothessentialstepsinthedesign main lagoonandamongthemid-shelfreefmatrix.
ISO MEMOIRS Of THE QUEENSLAND MUSEUM
Four Sites were chosen in an inshore area around ped inthequadrats.Thesettlementofanynew
the Palm islands (18.7°S. 146.5°E) in depths individuals on 0.25riv- concrete marker blocks
I
ranging from 20-30 m. Another tour sites were placed at one corner ofeach quadrat will also be
chosen in a mid-shelfarea in die vicinity ofthe recorded.
Slashers Reefs< 1S.5°S, 147.TH), indepthsranging To estimate lifetime growth curves in three
from 30-50 m. There is evidence that inshore years, We tagged across the full size-range of
areashave higherproductivity offood organisms individuals of several species common in the
pteorrsi.llcteormfmee.d)er-s,ctohnasneoqfufesnhtolryeadryenaasm(iAcdselceanPilhee, area,adnidndfiovridtuhaelnsee\vtetnhrseiexymeoanrtshsw.eTwhielldmoemaisnuarnet
expected to differ between these sites. Each site speciesincludedsponges{Xestospongia, lanthella,
waschosentocontain benthoshabitat wiihspecies Cy/nbusfcia, Jrcwtu), gorgonians {Cfenocella,
representative of those found on the types of Subergorgia, Semperina Menella, Junceelliii
seabedthaiaretrawledforprawnsorfin-fishes. MuriceUa, Echinogorgia)} and the hard coral
DEMOGRAPHY MEASUREMENTS OF Turhtnarta. We attempted to cover the size
spectrum available at each site by tagging 3-5
MEOABENTHOS, I he population dynamics of individuals, varyinginSize from smallto large,of
ilc- fauna that provide structural habitat is each species. The absolute size range depended
beingdocumentedby mappingthe dominantfauna on the species. After tagging individuals in the
at each site; tagging several dominant species of recruitment quadrat, the size spectrum was
sponges,gorgonians, andaleyonarianstoidentity completed by choosinganimals within a 20-30m
individuals; makingvideo measurementsofindivi- radiusofthequadrat.Typically35-50individuals
dual growth and mortality rates through time- were tagged at each site. Large and/orold sessile
observingthe occurrence ofnew small individuals my very slowly and, in a three-year
inquadrats formeasurementsofrecruitment;taking study, their growth may not be measured as
samples to confirm taxonomy; and histolo tsely as small or young fauna. To counter
examination in the laboratory to determinerepro- this, benthos are being measuredasaccurately as
ductive strategies. ibic, using laserseatingequipment and\ ideo
Ateach site, a4>3m quadrat wasestablished to imagecaptureandanalysistechniques(seebelow).
measure recruitment Initially, all individuals of The latitude/longitude position on the seabed
all species ofsessile launa within each quadrat ofeach tagged individual was recorded with an
were taggedsothattheappearance ofnew mdivi- underwater tracking syslem and differential OPS.
duals can he detected, mapped and tagged. Thepositionsoftagged individualsweremapped
Typically, 10-20 individuals were present and so they could be found easily on subsequent
Id
Age(yews)
! u I. i A. Exampleol a Pord-Walffordregressionplotofsize(yr '» vs. size(yr)toestimatetheparametersgrowth
rale A:(from slopes ' ) md asymptotic size i._ (from intersection ofregression With V X) lora hypothetical
speciesofsessile benthic fauna. B, The correspondingestimated von BertalanlTy growthcurve for thespecies
lhat may reach a size of 100cm after more than 20 years.
NEW METHODS FOR MEASURING DYNAMICS OF SPONGES 481
I ^——--DGPS& Radio-link tagswereattached tosessileepifaunabycable-ties,
———ClumpWinch or inserted into sponges with a large needle, or
V" -,.. moulded into epoxy pucks placed at the base of
the target animal. —
A small remotely operated vehicle (ROV
:: i 1 \ Hydrovision 'Offshore HYBALL') is beingused
toconductmostofthe underwatertasks. SCUBA
Tracking I divers assist to a maximum depth of 30 m, by
Receiver Umbi|ica| . 1 settingUpquadratsandtaggingbenthosinshallow
Responder sites. The ROV conducted these tasks on deeper
sites, where it can operateforvirtuallyunlimited
1 ROV periods. An acoustic underwatertrackingsystem
ClumpWeight ! » and differential GPS navigation enables accurate
(±lm) latitude/longitude position fixing and
locationoftagged faunaformeasurementateach
sampling time. The ROV telemetry link also
allows data such as tag numbers to be auto-
FIG. 2. Schematic diagram showing the method of
anchoring a 20 m vessel over the study sites and matically acquiredinrealtime,displayed, logged
deploymentofthe ROV on nylon rope. to database along with corresponding position,
video frame numbers and captured image file-
occasions, lor measurement. Growth of tagged names. A pair ofparallel lasers fitted inthe ROV
individuals will be estimated by measuringincrem- provide a 100mm scale on the video images of
ents in linear and/or areal dimensions seasonally. megabenthos for measurements. A manipulator
Growth curves ofthe von Bertalanffy form will ontheROVisusedtoapply tagsandtakesamples.
be parameterised by statistical analysis ofFord- Deployment ofthe ROV involves anchoring the
Walford Plots (e.g. Fig. 1; Gulland, 1983). vessel preciselyoverthe studysiteswitha800kg
Mortality will be estimated by the disappearance weight as an anchor on a 25mm plaited nylon
oftaggedindividuals.Mortality,whennotdirectly ropethatcan absorb up to30%riseand fall ofthe
observedfrom skeletalordecayedremains,canbe vessel on the waves (Fig. 2). The ROV umbilical
separated from tag loss by cross-checking any is clipped onto the ropetominimizethedragdue
apparentlosseswithaccuratepositioninformation tocurrents.Thismethodissimpleandeffectively
and the photographic record. enables repeated,accuratepositioningofthevessel
overthe study sites.
Every six months, separate specimens of the
same suite of species are being collected for Integrateddataacquisition,storageandretrieval
histological studies oi^ reproductive condition. are central to the logistics ofthe field operations
The taxonomy, identification and reproductive andanalysis.Customsoftwarecontrolsthisintegr-
sattutdhieeQsuoefenthselasnesdsMiluesfeauumn.aWareehbaeviengcounncdeenrttraakteend RatOioVn otfradcaktiangf,orvviedsesoelfproasmiet,ionanadndtaogrinenutmabtieorns,
on relatively few species ofstructurally dominant (Fig. 3). It alsoprovides anavigationsystem that
fauna and, even if we cannot assign scientific gives accuratecoordinatepositionsofthevehicle,
ennatmespsectioeesacahn,dwdeetweirlmlibneeawbhliectho sdiefpfaerraetnetdfioffremrs- dwihsipclhayaerdeaosvearnlaRidOVonttrhaeckviodneoaptlaopteterrecwoirnddoawn.d
belong to the same species. The positions oftaggedfaunaare shown as way-
points to facilitatetheirlocation (Fig. 4). Whena
LOGISTICS OF RESEARCH. Tagging in the tagged animal is detected, previous images ofthat
marineenvironmentistypicallytroubledbyfouling subjectaredisplayedforconfirmationandtoenable
andgrazingby fish, which leadtodifficulties with the same image orientation and perspective to be
tag reading and tag loss and associated ambig- captured.
uities. Tominimise theseproblems and facilitate Thelaserscaledimagesoffaunarecordedfrom
identification, the tags used in the study were theROV'svideocameraarecapturedliveorfrom
radio-frequency identification tags in 23x4mm tape. The lasers are calibratedby projecting onto
glass capsule form (Texas Instruments Rl-TRP- scaled grids to check accuracy and precision of
RRHP),thatwerereadautomaticallybyaninduction measurementsofsizethroughtime. Imageanalyses
transceiver (Texas Instruments TIRIS Series 2000 areachievedefficientlybyusingacustomsoftware
module) mounted in an underwater housing. The applicationtocontrol,linkandsynchronisethefield
482 MEMOIRS OF THE QUEENSLAND MUSEUM
FIG. 3. System diagram showing integration ofcomponents necessary for automated tracking ofthe ROV and
synchronous logging of position, tracking, tag numbers and video data, to facilitate post-analysis and
measurementofsessile benthic fauna. DGPS: differential global positioningsystem, VCR: videorecorder. PC:
logging computer, SCU: surface control unit for ROV, TXD: tracking system transducers.
DataBase: e:\Temp\mbd0296benthos1 mdb Event; 01 Hahitat 5
File: Option;: Par.3r1ief.ej:;:: ReterfyV:'.--
FIG. 4. User interface ofthe custom acquisition, tracking and logging software, showing vessel-relative ROV
tracker(rightwindow)andROVnavigationplotter(leftwindow)withwaypoints(e.g.0070to0074), ROVtrack
(irregularblack line), vessel position (arrowhead), ROVposition (pale circleoffstarboardbownear0073). The
lowerwindow shows dataacquired and status.
NEW METHODS FOR MEASURING DYNAMICS OF SPONGES 483
databases (of tracking, positioning, and tag choosesspeciesandconditioninformationfroma
numbers) with the video images and execute select list. The software transfers the measure-
macrosontheOptimas®imageanalysissoftware. ment data to a database along with the image
An operatordigitisesthelinesforthe laserpoints filename and corresponding field data. This
mm
(100 scale),height,width,andareaofprofile providesasemi-automatedmethodforextracting
as appropriate for the growth form (Fig. 5) and the required quantitative data in the form ofdate/
time, site, tag-number, species, position, morpho-
^^^i^i__ metries and condition.
fhMiiiifmBmttss
RESULTS
The first tagging fieldwork was conducted in
March 1998. Elevenofthemostabundantspecies
weretargetedfortaggingandatotalof174sessile
faunaweresuccessfullytagged,including26putat-
ive species. The available size-spectrum ofeach
species was successfully covered in most cases
(Table 1 ). Specimensofthesespecieswerecollec-
ted for taxonomic confirmation.
Thesecondtaggingfield tripiscurrentlyunder-
way (December 1998). In the four study sites
around the Palm Islands, 95% oftagged individ-
uals have been re-measured, 9 individuals were
not re-located, 5 incidences of mortality were
confirmed, and 13 new recaiits were observed in
the quadrats.
FIG. 5. Captured image ofa computer screen showing Todate,resultshavedemonstratedthatthelogistics
resultsofthemacrorunonOptimasbythecustomcontrol ofthe project are workingas planned. Taggedindiv-
software, to measure benthic fauna - Xestospongia iduals can be re-located successfully, tags can be
testndinaria in this example. The tag interrogator re-interrogated and cross-referenced in the database,
antenna is visible inthe lowerleftofthe image. captured images can be meas-
mm
uredwith accuracy,recruit-
TABLE 1. Listofspeciestargeted fortaggingduringfieldwork in March 1998, mentcanbeobservedandmortal-
with statistics ofeach species for height (cm) oftagged specimens, count of ities confirmed. The method-
numberstaggedbysize-categoriesinclassesofonestandarddeviation(sd)unit
ological protocols that have
relativetothe mean,andtotal count. ROV
been established for
Min Mean Max Small Mud-small Med-large Large Total deployment and for benthos
Species Height 1leiglu Height <-lsd -Ksd>0 0<sd>l -1 sd Count measurement will be used for
Ctenocella 10.6 34.1 69.9 4 6 8 4 22 futurerepeatedvisitstoindivi-
pectinata
dual tagged faunato provide a
Xestospongia 9.8 23.2 42.1 3 5 6 4 18 consistent series of measure-
testndinaria
ments.
Menelki 5.0 18.0 28.9 2 3 10 1 16
Cymbastela
concentrica 9.4 21.6 43.5 3 4 4 2 13 DISCUSSION
Surbeetricguolragtiaa 14.6 43.9 108.1 2 4 4 3 13 Our study has developed
Turbinaria 2.0 24.4 62.0 1 5 6 1 13 techniques for in situ invest-
Semperina igations ofthe types oflarge
brunei 10.0 34.6 53.3 1 4 7 1 13 sessile fauna that provide
lanbtahsetlala 16.8 31.0 46.7 4 1 4 2 11 satrreuacst,uwrhalerheabaictcaetssibnyddeievpeersr
Jimceella 9.0 27.5 41.2 2 2 7 11 islimitedorimpossibleusing
divergens conventional breathing
Muricella 13.1 25.9 40.7 1 4 4 2 11 equipment. These methods
Eehinogorgia 20.4 33.6 45.8 1 2 2 1 6 opentheopportunityforunder-
Others 27 standing the poorly known
!
4*4 MEMOfRS OF THE QUEENSLAND MUSEUM
ecology ofthese Eannas, and will lead to gr< ACKNOWLEDGEJVffiNTS
appreciation of their role and importance. The The Fishing Industry Research and Develop-
study will also document U&agC ofliving habitat ment Corporation. CS1KO. AIMS and the
by key fin-fish species, in terra of species Queensland Museum are funding this project. B.
in linuktsjon, shciici requirements and o11nillthaendmaI)n. Vancepro\-idedconstructivectilieism
The growth, mortald\ and reu.inmeni
i
i by tflfS stuclv WJll he used tor develop- LITERATURECITED
ing p|oeplualuantai.onTlideryedsntarmmuaicttcrusirxemofofodrtehmless(eeo.mfg.odtheHelosgl]awirlgle viULLYAorNkb).,j.,\. 1I98kJ3s.*lFlis\h<SJt.oWciklex\In\ter-Seiciu.L i uaJ
1984). Basically, for each species, the models HOOPER J.N.A., UHINN, FU". & MURPHY, I'.T,
.ill have several size categories, the numher of I99S invi rtebrales
h will depend on life history chant*. : Pp. i1 lingsofiheBic.prospL-cline.
&
recruitment to the ill be FMotechmtlog) Biii
the probability olsetlk Western Australia: Perl
category will ra sivi recruitment due to growth HUGHES T.P 1984. Population i based on
lower iCtttet<gorj will haid indi ' indh •oil reef ex m - men w tl h
dying or growing to the n tsizi calegoiy (the HUTCHtNGS, fftctsol ti
jjovmIi will also be included tig. oj n • enthi ifauual communities.
ifrequired Other factors to be included in the i : 'oumal Of Marine and Freshwater
models includ ofdensity of i . iri h il-lil-i rj
dthueclsivaemepoatenndtioatlhearndbepnrtohxomsnltay\ao,rasnodurtcheeproeppurlo-- i iintheO: UiR WI o;rld Heritage Area Pp, 323-J53m4hoIsn
ations on supply OfIan
nuRmesbueltr:-o,loifstshuiefsl,sitnucdlyudcianng,bethueseesdtatboleixsahmmie,ntof RGegBcehRfniMMiaPrAin"eWo!>Prairhki Ai1uPtrhoocreietdyi:ngfs1o,3w.nNso(vivielnl-ie)-.B rrie
rhaebfiutLgaietonr.aerseFtaloisreastoinon,tlst..akerheboVelOddl,eVrCtcrmoanowfulliincndtgs,tslatirenadlivmipact PJTCHIEJR.&CPOlvI-NBERU,RoRIiKI.DG1GB9R&97Cs^erah,be\eeYdf\fSehcSat.bsitoaftsp.;raPwpn.
oftrawlingon seabedhabitatand associatedstocks, tie tueat Barrier Reef $<
and the rate of recovery ofhabital ifareas were and nra la national c< ttfetence: Proc-
eeclu Banner Reef Marine Park
ved. In particular, models will contribu
illei
the development of management _, to POINFR. I.R., GI.-MS'ITR, J.. PITCHER, C.R.,
improve theenvironmental stistainability ol trawI- BL1RR1DG1 .C^WASSENBERG, CGRIBBI E,
oithg\,vby simula;,t:,iwnigtthhteheindteyruaacmtiiocnsoolftthreawdlyinmapmics BRPiWilil.ik„ B„D.B&IAEBLFIR.is,S.vJ.M.1,99M8.ILFTbOeNc,mP.M.,
and estimating levels ot'trawl effort that do not mcL ofpcawncrawGng inthefarnorthern
cause continuing degradation. sectk n Greal Barrier M -96. t inal
RDCCSIRO
Information ol this kind will become inci Iarine Research Qidueiensland DepartDmiveinstioonf
inglj important as the requirement for ecologic- Primary Industries Report. (( S1RO: Bristol
ally sustainable fisheries management is URY.K.J.XAMPBEl I..R.A.. UNDHOI M,
implemented in trawl fisheries lrorn ihc Lcmperate R.& WIIITKLAW.W. 1997- I xtxrimenuxlm.,,
to the tropics. The lessons learned Jrom this meut af tn Australian a hcty:
study in the form of knowledge o\' habitat Examiningthepossibility oftrawl-induced hi
dynamics, and methods lor monitoring habitats modift ttit ii &Pp u>7-l 12 ll- Pikilcb, E.K.,
and the commercial stocks they support, will l-luppcrt, D.D. Sissenwine, M.P. teds) Global
Fisheries Management. (American
contribute top rational balance between ecolog- i Man
Fisheries Society: land),
cicoanlsleyrvsatuisotnainwahbelne fBiSsDhinrgelaatnedd bmiaondaigveermseintty van DjOL1A98H7., Eif'f'ectVsyoEfNDaTr,esPeaHr.ch&trNaIwClIIoOnIashoanr.d
objectives are implemented in those Australian bottom assemblage of sponges and corals.
fisheries dependent on seabed habitat. Fisheries Research 5*39^54
