Mar.Lile 1994'Vol.4 (1 ) : 15'19

Massmortality of paramuriceaclavata (Anthozoat ) on PortofinoProlnontorY cliffs, LigurianSea, Mediterranean Sea ' Mortalite ntassivecle Paranruricea clavata (Atilltozoa, Cnidaria) nter Méditerranée surla falaiseclu prontontoirede Portofirt(),tner Ligttrienne,

Carlo Cerrano*' Ciorgio Bavestrello*,Stefatlia Bertone**, lì,ic.tarclo Cattaneo-Vietti*, EldaCaino*, Daniclc Zanzi***' 16126cenova * lstitutc.rtli Zoologia clell'Urriversitiì tli cerrov.r, via ualbi,5,l- XV,10, | - 16132Cenova ** lstirutodi Microbiologio?"fi'Ú"i""rsitàcliCenov.r, Viale Benedetto *** Acuuariodi C",.,uuu,Area porto Antictr, l,.,rrte Spinola, l- 16123Cenova

zoobenthos marin, nter Méditerranée' Motsclés : gorgonaire-s,Pararrruricea clavata, mortalité trt;tssive, zoobenthos' Mediterranean Sea' Key-words : gorgonians, clavata, massn'rort,tliIy, ntarine

ABSTRACT (ì;tirn, D' Z'trtzi, 1!)94 - Massrttortality of Paranrurice'rclavat'l IJ;tvestrt'lloC.,5. tsertone,R. Caltaneo-Vietti,C. Cerrano, E. Sea'Mar' Life,4 (1) : 15 - l9' (Arilltozoa,Crticlaria) or''po,ì1rriii'o p,ion',rrntory cliífs, Ligtrrian-Se;r. Mtr/ife'ranean pararrrurice.r clavata on the Portofínct Promontory is reported' A, extrente caseof ntass ntorta!ity of the sea fan ttt clcpthrtytge, underwent a clegenerative During Octobertg% a'o,uito,óoo seafans, livinl4 irr llrc20 tt-t.J5 front tlrcg

ck.ptlr.At greaterdepths tlris is re;llacctllly INTRODUCTION l,,lranturiìt..aclavata (lìisso), the biggestMecliterra- (Weinberg,1991), wlrose population Arrthozoansare an inrportantconlponent of the ncan seiìfan lras a very slow corallig,enousbiocoenosis on Mediterraneansub- is very stable,and which Srowtll 'X, 60 nrm/year(Peirano' nrarine cliffs, reaching 95 of tlre total bionrass r.rte,ianging -19ti9; front 12.5 to 1991 Mistri et 'tl'' in sonreareas (Cili, Ros, l9tl5). Atlotrg,the gorg,o- I rrrrcsi, Weinberg, ; of this l()()2). rrinns,wltich are tl-remain represetrtatives 'l a clramaticcase of nrass biocoerrosis(Pérès, Picard, 1964), Ettnicellasingu- he presentnote rellorts of P'tr'trrt(/rr('c'ì /ari-s(Eslrer) is conrtlronly fclr'rrrclor.r lrorizont'rl or' rrrort.rlityinvolvirlg a lroprrlation the'verticalcliffs at PortoiintlFartl sub-lrorizontal bottorlrswllereas E' cavctlinii

l5 BAVESTRELI-OC., S. BERTONE, R. CATTANEO'VIEITI, C.CERÍìANO, E. CAINO, D. ZANZI

RESULTSAND DISCUSSION Scuba clivingsurvc'ys along tlre trortheasternand sorrthernsiclcs of PortoiinclFaro (Portofino Pronron- The occrtrrenceof a wirlcsltrcaclgr

- Figure I - M1rrlthologic.rlaspects oí lhe largr'-sr,ìl('nì()rt.rlily ;rííecting I'tr.tttturi

,ttt 2titnts

l(r MORTALITÉMASSIVE DE PARAMURICEA,/MASSMORTALITY OF PARAMURICEA

population ends at 50 m on a detritic bottonr.On tlre southernside, P. clavata is presentfrom 28 nl and reachesmaximum densityat 38 m depth with about 12 colonies/mz. rJ21 In mid-September1993 no obvioussig,ns of damag,eto ; the colonieswere observed.But during a surveyon 20th Octoberextettsive ntortality was detected,affec- ting the coloniesliving, from 20 to 38 rn deptlr.The E area affectedcovered was about 800 nrz willr an ave- ragepopulation density of 12 colonies/nr2.In particu- .l lar, from 20 Io 25 m, 00 % of the colonieswere involved.Among these,about 20 % showedclear signsof necrosis(Figure 1a) with prog,ressivedetach- (Fig,ure nrentof the livingtissue 1b),whereas in about salinity(ppt) was exposed.The expo- B0 %, only the bareskeleton ' Figure 2 - Hydrographic conditions (temperatureversus salinily) sed skeletonswere abundantlycovered by epibiontic of the surfacewater column (O-35 m depth) of a site (St.A) (9' t hydroids (Obelia, Cantpanulariaand Clytia). From 14' E, 44" l8' N), insidethe Marconi Cul( 2.7 km front the Porto- after 25 m, the percentageof affectedcolonies decreased fino Faro. lhe data, collected on 30th Septemberl99l heavy rainfall, denronstratethe presence of an upper layer (0- graduallyand below 38 m no damagewas detected. 10 rn) characterizedby low salinityand temperature.lConctitions Overall, about 10,000 specinlenswere involved irr hydrographiques (température et salinité) à la staliott A, située this rnassmortality. The pherromenonwas lintited dans le golfe Marconi a 2,7 km du phare de Portofirto. Les clon' nées recueillies Ie 30 seplentbre 1993, après une J:ériode to the PortofinoFaro area ; itr severalother investi- d'or,tg,es, montrenl Ia présence d'une couche superficielle c.trac' gated sites no degenerativesigns were observed. térisè.epar des valeurs basses de salinité et de tenttrtérature (by Scanningelectron micrograplrs confirrned that seve- courtesy of ISAM, Uníversity of Cenova). ral sectorsof the colony's branclreswere complete- ly spoiled(Figure 1c), whereas others were involved Other marine organisnrshave been involved in in a proliferativeactivity of tlre coenenchymarevea- large-scalenrortality irr both Caribbeanand Medi- led by the spreaclingof living tissueover the bare terraneanareas. Commercial spong,ebecls were skeleton(Figure 1cl). clepletedin 1938-1939by a diseasethat rapidly Mass nrortality events are well documented for spreadoutwards causingsevere reduction in the "bleaching" nradreporiancorals and ;eported as sporlgepopulations (Caltsoff, 1942).In the Mediter- phenonrena(e.g. von Prahl,1986; Pecheux,1993). riìneanbasin a more recentepidemic causedheavy [ìy contrast,few clataare availablefor seafan popu- Iossesitt sponge [rionrass(Caino, Pronzato,1992); lations,apart from tlroseconting from the Southern the spongebody was reducedto a networkof brittle Caribbean, where two species of Gorgonía were fibres contanrinatedby bacteria (Caino, Pronzato, sporadicallyinvolved in heavy mortality phenome- 19iì9). na. ln this area Corgonia ventalinarepresents the As far as tlte gorgoniansare concerned,nlany phy- sical arrd biologi<.alcauses have beer.rcitecl t<-r nrostaburrclant species. Mortality was firstobservcd -Irirri- in Novetrrberl9t]1 along the north coastof cxlllairrthese ntortalities (Cuzntatr, Cortc\s, I984), rlacl(Layrloo, 19U3). The following year other sPe- r:vcnthoul;l'r it is very clifficulttcl attribute tlreir mor' cies were affectccJ,such as Cor21

nians.Two samplesof both the healthy ancl the As reportedfor sponges(Gaino, Pronzato,1989), P. damagedgorgonians were shakenwith small sterile clavata also showed, in some cases,reparative glassballs (diameter 2 mm) in 10 ml of sterilesea mechanismsallowing partially damaged specimens water for 10 minutes : the bacterialsuspension after to recover bryregenerative processes. lhis feature dilutionwas spreadon marineagar plates (2216 representsa successfulstrategy to face nlass morta- Difco) and incubatedat room temperatttre(23- lity and to survive. 25'C). Five days later,bacterial colonies with diffe- rent morphology were selecteclas differentstrains and isolatedon marine agar : a total of I0 ancl9 ACKNOWLEDGMENTS bacterialstrains were recoveredfrom the damaged .l We aregrateful to Prof.N. DellaCroce, Instituto'di and healthycolonies respectively,and 4 from sea ScienzeAmbientali Marine dell'Università di Ceno- water.The bacterialstrains, all Cram-negativerods, va,for the physicaldata on thesea water column in were identifiedby analysisof their gas chromato- thestudied area. graphicfatty acid composition: the fatty acid profi- le of an unknown strainis comparedto a data base of standardprofiles (Bertone et al., 1993). No pre- REFERENCES dom inant strains were detectedamong those colonies.ln a general coming from the damag,ed Atrstin8., 19SB- MarineMicrobiology, Canrllridge Uni- of tlre healthyancl sensethe microfloracomposition versityPress, New York,)22 1:P. damagedgorgonians appeared to be rathersinlilar, BavestrelloC., F. Boero,1986 - Necrosie rigenerazione reflectingthe speciespresent in the sr:rrountlirtg in Eunicellacavolinii (, Cnidaria) in Mar water (Tablel). ln addition,the valuesof 6 x 104 ligure. Boll. Mus. Ist.biol. Univ. Cenova,52 : 295' and 3 x 10q bacteria/cm2found on the surfaceof 300. diseasedand healthy colonies respectively,do not BertoneS., L. Casareto,R. Berti,S. Reina,M. Ciacomini, - A new identification show significantdifferences with regardto the bac- C. Ruggiero,L. Caleg,ari,1993 of marineheterotrophic aerobic bacteria terialcharge (Austin, 19Bg). technology performedan informaticalgorithm basecl on a neural Evenconsidering the predatoryactivity of Gastropo- net elaborationof whole cellularfatty acid profiles. it is well known that colonies da and Polychaeta, ln : 6th EuropeanCongress on Biotechnology,13-17 predators are not completely destroyed by these lLrnel993, Florence, Abstr. Vol. lll, 195pp. (Cuzman,Cortés, 1984; Theodor,1967). Finally, DellaCroce N., A Covazzi,A. Bonomi,1994 - Valoricli the presence of the alga Dictyota dichotoma on P. nei mari Liguree Tirreno'Atti X transparenza .l clavatawas recordedduring the summer,especially CongressoA/Ot, Alassio: 25-133. on coloniesliving below a depth of 35 m, but very CainoE., R. Pronzato,1989 - Ultrastructuralevidence of (Porife- few colonies there were affectedby the mortality. bacterialdamage to Spongiaofficinalis fibres ra,Demospongiae). Dis. aquat. Or8.,6 :67-74. CainoE., R. Pronzato,1992 - Epidemiee Pescaintensiva Table | - ldentifiedbacterial strains from Paramuriceac/.rvaLr an

1967- Corrtributionà l'étudedes gorg'ones PeiranoA., L. Tunesi,1989 - Modificazioninella compo- Théodor)., (Vl) desbranches de gorgonespar cles sizionedel popolamentoad antozoidel corallig,eno.cli : la dénudation prédateurs.Vie Milieu,l8 A (1| :73-78' PuntaMesco (Mar Lig,ure cli Levante)a 30 annidalle nrollusques 1958- Biononriamarina della regione cos- orinreosservazioni. Nova Thalassia, 10 : 543-548' TortoneseE., tierafra Purrtadella Chiappa e Portofino.Archo Ocea- Perès J.Picard, 1964 - Nouveaumanuel de Bionomie ,|., 11 : 167 -21O' bentlriquede la nrerMéditerranée. Rec/. Trav' Stn' nogr.Linlnol', - Nuovocorrtributo alla conoscenza ntar.Endounte, 47 : 1-137. TortoneseE., 196'l clellascogliera ligure' Archo Oceanogr' PeucheuxM., 1991- ls presentcoral reef mass bleaching clelbenthos 12 : 163-l 83. cfue to CO2 rise ? In '. Biontineralization93' The Ttlt Lirrutol., 1g7B- Mediterraneanoctocorallium conr- Int.5ymp.'on Biomirreralization, 17-20 Novenrber Weinberg5., n'runiìiesand the abioticenvironment' Mar' Biol',49 : 1993, Monaco : PP.1 1 2. PralH. von, 1986 - Mortalityof lrermatypiccorals irr 41-57. 1991- Faut-ilprotéger les gorgones de la Anrericaas resultof El Nirrophenomena 1982-1983' WeinbergS., ? In : les espècesntarines à protégeren ErfenBull., 17 :14-15 Médiierranée C.F. Boudouresque,M. Avon, V' Cra- RivoireC., 1991- Mortalitédu corailet desGorg,ones en Méditerranee, (eds.), publ.,Fr., pp :47'52' profondeurau largedes cÓtesprovenqales' In : Les vez Cl5Posidonie espècesntarines à protegeren Méditerranée,C'F' Boudouresque,M. Avorr,V. Cravez(eds'), C15 Posi- donieptrbl., Fr., pP : 53-59. Reguen janviert994 ; acceptéen avríl 1994' Rossi1., 1965- Iniluerrzadei fattoriambientali sulla RecelvedJanuary 1994 ; acceptedApril 1994' faciesa Gorgonaceidi PuntaMesco (Riviera cli Levan- Ie\.Boll. Zool.,32 : 859-865.

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