Growth, reproductive biology and habitat selection of the sea urchin. - Paracentrotus lividus in .... for 3 patches of each habitat were randomly pho- tograpbed.
Echincderm Research 2üü1,Féral& David (eds.) Q 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 528 2
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Growth, reproductive biology and habitat selection of the sea urchin Paracentrotus lividus in the coastal waters of Cascais, Portugal J. Gago, F! Range & O. Luís Labomtório Mm'fUno da Fuia/LMARNnivemidndede Lisboa, Casais, Porfugol
ABSTRACT: The edible x a urcbin Pomcenfmrus lividiis (Lamarck 1816) is the dorninant echinoid species along the Pomguese coast. In the coastal waters of Cascais, it can be found on iwo types of rocky subtidal babitais: nip-sha ed cavities with encrusting aigae pavements (barren grounds) where it occurs iii higli densities (234.4 indim ) or, at a lowerdensity (7.5 indlmz) in surfaces witherect algae cover without shelters. Inthe present study, some alimcntary, reoroductive and growth paraineters were ~eriodicallvassessed kom June 1999 to July 2000 for w urdiins çoll&ted imm thesAwu habitats. The orgaiiii and inoianic fractions ofthe ~ ucont tents ~ t e a l i dsc.,son.~lfliiautions in alga1 ~ l ~ u n h aiid c c wavc action significanily a k r tla fedina beliaviour. Variabiilitv in the eonad index indicated soawnine occurred duriné snnne and summer and that focd availability affects the size of the gonads. X-ray anaiysis of the growth bands on coronal test plates indicated a h i a e r 2 n d rale in urchins collected from the erect aleae habitat. Loneevitv - .was about 8 vears for individuals fmiii both hiibitatr. Tlie hipJier iiivestmetits in reprodui.tion and gruwth ~TindividunlsCullected from lhe ercct aleae Iiabit $1is relatid to supiiior food a\.allabilit) ard qu.ilir, Diiisrences i i i ihe biolcgical paidmeim studiedirobably correspond to different lifc strategies adopted by s& urchins in each habitat. ~~rvaesettlement is expected to be more intense on barren grounds. At a certain moment of the life cycle, a mnsiderable portion of lhe population probably migrates frorn barren groiinds to the erect algae habitat.
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INTRODUCTION
strenethened bv Lhe fact that few lame and abundant herbivorous manne invençbrates occw uva its emEchinoids in eeneral and the remilar sea urchins in ar t~hii:iIrange IUouJa~lr~ouc & \.rlaaiie 2 .01. This sea &hiu is edible'and for a ]óug timc has particular haveaprepondemt r o i onmarine communitv stnicture and dwamics, esiiecially on coastal been fished for human consumption (Allain 1972). habitats. Their actioi has been noticed on seagrass This fishery is not important in Portugal. meadows (Valentine & Heck 199 I), kelp forests and In the coastal waten of Cascais R lividus is the other macmaieae biocenosis (Lawrence 1975. dominant sea urchin occupying iwo different kinds of Hawkius & ~ar&oll1983,~ c h e i b l h1986,~einaas& rocky habitats. On the habitat usually designated as Christie 1996), and intertidal oools Paine & Vadas barren grounds sea urchii can be found at a liigb b i Cin.kli 1995). Conceming density, occupying cnp-shaped cavities with ennust1969, ~ e n e d e k - ~ e e c & the sea urchin Paracentmtus lividus (Lamarck 1816) ing Corallinaceae. Very near these barren gmunds, its acriun on alga1 populations lias heen described in ? lividus also inhabits, ata lowerdensity, surfaces with thc Easi Arlbniic (eg. Kircliuig & Eblmg 1961. Pastor ereot dgae cwer without shelters. The present paper tries to explain this spatial dis1971). hut mainlv in lhe Meditcrranean (e.e Keniof 1962: N6delec i982, Verlaque & ~ 6 d e G c1983, tnbution, based on a comparative study of feeding Vedaaue 1984, Azzolina 1988, Ruinon et a/. 2000). behaviour, reproduction and growth of EI lividto on Thr. ieeilingictivity of this species causes sevcre mod- the two studied habitats. ifi.alionj in ihe Licnth.r coromuni:y segewl composition. The relative abundance of &verai aleal sc&ies 2 MATERIAL AND METHODS that are not eateu leads to tbe formatio; offacies where only the calcareous encmsting algae persist 2.1 Stwáy area (Nédelec 1982). Even in low densities P lividur can influente the stnicture of alga1 assemblages (Palacin The study area (Fig. 1) is located on the central e1 ai. 1998). The ecologicai role of this species is west coast of Portugal near tbe village of Cascais, u
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was used, at 5 mA intensity and 25 kV potential difference. The exposure time was dependent on the i~iicknessofthe~iaic~, hiii always lessihan 5 miiiiiics i'hc skeletal plates local~>cr of individuals. On thr .,rher hand in rhr erect ale ic habitat I! lividus can graze on rocky areas with higher food availability, leading to greater developments in reproduction and growth The reduced number of w i c e s in this habitat could explain the dominance of large individuals since they are not so susceptive to predation (Boudouresque & Verlaque 2001). The hieh densitv and the oredominance of small individuais in barren grounds indicates juvenile recruitment is vem stronn in this habitat. Oooositelv. in erect algae habitat the prevaience of &e aduit individuals over the juvenile stages suggests larva1 settlement is not the major source ofrecmits. Recmitment by migration from barren gmunds can be an important origin of new individuais to this habitat. Azzolina (1995) hypothesized the occurrence of
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migr;ltions to :\plain differenczs fomo i i i the demoarapni? shucture of I' lividu.\ irom tu0 habitlts dis& about 100 metem. Longevity appears to be the same in both habitats. This implies that any migration occurring cannot be generalised to the entire i!lividur population. These migrations could be related to the development of the herbivore capacity with gmwth. Verlaque (1984) established that relation for i! Iividus and foundthe diet changes fromencmting algae and epi~hvtes to fleshv and erect alzae. Boudouresque & * . Ve~laque(2001j refer that i!lgidris food preferences are size dependent. Guillou & Michel (1993) also from related mi&ation of Sphereckinur calcareous algae habitats to Zostera spp. meadows and macroalgae rocky habitats with vari%ions in feeding behaviour
ACKNOWLEDGEMENTS The comnal test olates radioeraobic analvsis would not have been poisible withoit the collabóration and technical sumort of Dr. Armando Almeida. n i i s researcb wai- financed by FCT and IMAR. The authon would also like to thank two anonymous referees for their helpful comments on the manuscript.
REFERENCES Allain J.Y. 1972.La pêche aux oursins dans le monde. Pêche Maril. 74: 625-630. Allain J.Y. 1975. Smiehire des populations de hmcenlrottis iividus (Lamarck) (Echinodemata, Echinoidea) soumises à Ia pêche sur les côtes Nord de Bretagne. Ree Tmu Inst. Pêcher Marit. 39(2): 171-212. Allain J.Y. 1978.Age et missmce de Pamcentmtus liuidus (Lamarck) et de Pmechinur milimir (Gmelin) des &tes nord de Bretagne (Echidea). Coh. BioL Ma>: 19: 11-21 Azzolina J. 1988. Conhiburionà iètudede 10 dynomique de I'oursin comsiible Pomceniroru lividus (Lmck). Cmissance, IEcrutemenl, mortolifé, migmtions. Thèse
Dact., Université d'Aix-Maneille 11. 242 pp. Bncci G. 1954.Alcuni casi de inversione sessuale nei ricci di m e . Boll.2001 21: 45-49. Benedeni-Cecchi L. & Cinelli F 1995. Habitat heterogeneity, ssca mhin grazing and the distribution of algae in littoral rack pools on the wea coast of Italy ( m s t w Mediteminem). Mar. Ecoi. Pmg. Ser 126: 203-212. Boudouxsque, C.F. & Veriaque, M. 2001. Eeology of Porncenbwhrr iiuidus. In John M . Lawrence (ed.),Edible seo urchim: biology andecology. Amsterdam: Elsevier. Byrne M. 1990.Annual repiodunive cycles of the commercial sea urchin Pamcenbwtus lividur from an cxposed intertidal and a sheltered subtidal habitat on the west mas1 of hland. Mai: Biol. 104: 275-289.
