PRESENT STATE OF DECAPODS SPECIES FROM THE ROCKY COAST OF ROMANIAN BLACK SEA

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1 PRESENT STATE OF DECAPODS SPECIES FROM THE ROCKY COAST OF ROMANIAN BLACK SEA Sanziana GHITAN 1 and Beatrice KELEMEN 2 1 Marine Biological Station Prof. Dr. I. Borcea, Al. I. Cuza University of Iasi, Romania, sanziana_micu@yahoo.com 2 Babes Bolyai University, Treboniu Laurian Street, Cluj-Napoca, bkelemen@hasdeu.ubbcluj.ro Abstract. Decapods represent an ecologically important macrozoobenthic link for the Romanian marine coast. Our recently data suggest that for some populations, there is a serious declining trend (Clibanarius erythropus, Carcinus aestuarii), but for other species (Eriphia verrucosa, Xantho poressa, Pilumnus hirtellus, Pachygrapsus marmoratus) there is an increasing trend in number of specimens. The purpose of this study is to increase the understandings in biodiversity of decapods species from the Romanian rocky littoral. Data were gathered during the collecting expeditions organized in 2007, using both classic and new (underwater visual census) sampling methods. Keywords: decapods, rocky substratum, dominant species. Rezumat. Starea actuala a speciilor de decapode de la litoralul dur romanesc. Crustaceele decapode reprezinta o importanta nisa ecologica macrozoobentica pentru litoralul romanesc. Datele noastre sugereaza ca pentru unele populatii se evidentiaza o declin semnificativ (Clibanarius erythropus, Carcinus aestuarii), in timp ce pentru alte specii (Eriphia verrucosa, Xantho poressa, Pilumnus hirtellus, Pachygrapsus marmoratus) se inregistreaza o crestere numerica. Scopul acestui studiu este prezentarea starii actuale si distributiei speciilor de decapode de la substratul dur al litoralului romanesc. Datele au fost colectate in timpul campaniilor de prelevare din 2007, folosindu-se atat metodele clasice de colectare cat si metode noi (censusul vizual subacvatic). Cuvinte cheie: crustacee decapode, substrat dur, specii dominante. Introduction Benthic studies performed between s on Romanian Black Sea rocky coast revealed that the rocky facies was a discontinuous strip located in the next vicinity of the high clayey-limestone seawalls (Bacescu et al., 1971). Rocky platforms had extended from the shore up to depths of 7m, at Cap Midia and 23m at Mangalia. The average depth of the rocky substratum was approximately around 14m. Hydrotechnical constructions that took place in the last decades of the XX-th century (the extension of Sulina dyke, the construction of the Danube-Black Sea channel), winter hard frost, waste water pollution changed irreversibly the configuration of the rocky biotope and its biocoenoses. Decapods crustaceans represent an appropriate group that can be used as model for studying the complexity of processes that characterize the biocoenoses: habitat selection, larval mortality, ecological relationships between decapods and other benthic invertebrates, due to their mobility, their life history and population dynamics. They play an important role in the ecological processes, in the dynamics of coastal benthic ecosystems, due to their high abundance in the rocky areas and high taxonomic and trophic diversity (Ingle, 1996). Previous studies conducted on the rocky biocoenoses indicated a serious decrease and even disappearance of some marine decapods species (Gutu, 1980; Tiganus, 1992; -27-

2 Sanziana Ghitan & Beatrice Kelemen Micu &, Abaza, 2004; Micu & Micu 2006). For that reason, we aim at presenting the actual state of richness and distribution of decapods that inhabit the benthic biocoenoses from the rocky coast of the Romanian Black Sea. Material and Methods Samples were taken in 2007, in March, May, July, September and November period. There were established four profiles (Constanta, Agigea, Tuzla, Vama Veche) and on every profile were fixed three stations at 3m, 6m and 10m depth. Sampling was done along transects placed perpendicularly to the coastline, each separated from other by app. 20m. Samples were taken handly, by lifting the rocks or by placing a 25 25cm quadrat metal frame on the substratum. Samples were washed and put in plastic bags. After, decapods were separated and preserved in 4% formaldehyde and for long conservation in 70% alcohol. Specimens were identified following taxonomic descriptions of Bacescu (1967) and Cedric d Udekem d Acoz (1999). Data analysis. Species richness (number of collected species) (Krebs, 1994, Stiling 1999), density (ind/m2), density index (Shannon-Weaver), evenness index (Pielou) and similarity index (Bray-Curtis) were determined for each species. Results and Discussion A number of 4182 specimens were identified in our observations belonging to 12 species. Pisidia longicornis, Athanas nistescens and Xantho poressa were the species with the highest abundances: 853ind, 719ind and 702ind. Pachygrapsus marmoratus, Pilumnus hirtellus and the palaemonid Palaemon elegans had a constant distribution along the rocky coast no of specimens Constanta Agigea Tuzla Vama Veche profiles Figure 1. Numerical distribution of decapods specimens on profiles. By contrast, the hermit crab Clibanarius erythropus and the grapsid Brachynotus sexdentatus had the most limited area of distribution. -28-

3 Brachynotus sexdentatus has a severely fragmented habitat, after a continuous decline in extent of occurrence, area of occupancy and number of locations. There are no compact populations along the coast, its subpopulations occupy some suitable patches of habitat in clayey substratum. (this species lives in holes made by Pholas dactylus). After great storms, silting represents the most significant danger, which affects this crab species. The survival of the metapopulation depends on the rate of local extinction of occupied patches and the rate of recolonization (Micu & Micu, 2006). Shannon Weaver index among the sampling stations was very similar, in accordance with the species richness. It varied between 1.18 and The highest value was registered at Agigea 6m. WPGMA VV3 T3 A3 VV6 VV10 T10 A10 T6 A6 C6 C3 1,2 1 0,8 0,6 0,4 0,2 0 Bray Curtis - Data log(10) transformed Figure 2. Coordination Analysis graphic of Bray Curtis similarity between stations upon taxonomic community structure in March Stations disposing on the CA graphic indicate the particular situation of Vama Veche 3m station. The alternating sandy and rocky substrata and the variety of macrophytic associations with perennial and annual algae is a premise of such a diversity of benthic species in Vama Veche. Cystoseira sea belts had a high tridimensional complexity, which made it unique habitat that harboured the most diverse fauna of all benthic biocoenoses in the Romanian Black Sea. -29-

4 Sanziana Ghitan & Beatrice Kelemen WPGMA VV3 VV6 VV10 T10 T6 T3 A10 A6 A3 C6 C3 0,48 0,4 0,32 0,24 0,16 0,08 0 Bray Curtis - Data log(10) transformed Figure 3. Coordination Analysis graphic of Bray Curtis similarity between stations upon taxonomic community structure in July WPGMA C6 VV6 VV3 VV10 T10 A10 A6 T6 T3 A3 C3 0,6 0,5 0,4 0,3 0,2 0,1 0 Bray Curtis - Data log(10) transformed Figure 4. Coordination Analysis graphic of Bray Curtis similarity between stations upon taxonomic community structure in November

5 On Agigea profile we identified 12 species of decapods, Athanas nitescens, Pisidia longicornis and Xantho poressa were the species with the higher abundances for all five months of collecting samples Athanas Psidia Xantho 5 0 martie mai iulie sept noiemb Figure 5. Densities (ind/m 2 ) of the three dominant species on Agigea 6m Athanas Psidia Xantho martie mai iulie sept noiemb Figure 6. Densities (ind/m 2 ) of the three dominant species on Agigea 10m. -31-

6 Sanziana Ghitan & Beatrice Kelemen The highest number of species and specimens were identified in Agigea profile, Pisidia longicornis being the dominant species. The lowest number of species was identified in Constanta 3m. Pisidia longicornis was the dominant species with 853 (20.4%) specimens, followed by Athanas nitescens, with 719 (17.2%) specimens and Xantho poressa, with 702 specimens (16.8%). 20,4% 17,2% 1% 1% 0% 1% 5,7% 6,3% 15,6% 15% 16,8% Athanas Pilumnus Xantho P. elegans Pachygrapsus Rhithropanopeus P. adspersus Eriphia Carcinus Clibanarius Brachynotus Pisidia Figure 7. Numerical dominance spectrum of rocky decapods species. Conclusions Distribution of decapods species varies along the rocky coast, depending on diversity and complexity of resources. Agigea is the most representative profile for Romanian rocky littoral; here we identified 12 species of decapods and 1544 specimens. There are species which inhabit different types of habitats, Rhitropanopeus harrisii and Palaemon adspersus are common species for both stony and sandy substrata. By contrast, there are species which prefer a single biotope, as the case of Brachynotus sexdentatus, that lives in holes made by Pholas dactylus in the clayey rock. Pisidia longicornis, Athanas nitescens and Xantho poressa are the three dominant species of decapods that inhabit the rocky substratum of Romanian Black Sea. Most decapods were found under rocks, among filamentous algae. Acknowledgements. Part of this study was possible through the project CNCSIS PN-II-IDEI-PCE, 116/2008, funded by the Romanian Ministry of Education. -32-

7 References Bacescu, M., Fauna R.S.R. Crustacea. IV (9): Decapoda, Editura Academiei R.S.R, Bucuresti. Bacescu, M., Muller, G., Gomoiu, M. T., Ecologie Marina, Editura Academiei R.S.R., IV: Gutu, M., Recent changes in the decapod fauna of the Romanian Black Sea littoral. Trav. Mus. Hist. Nat. Gr. Antipa, (21): Ingle, R., W., Shallow-water crabs. In: Barnes R.S.K., Crothers J.H., Synopses of the British Fauna, 25. London, The Linnean Society of London and the Estuarine and Coastal Sciences Association. Krebs, C.J., Ecology. The experimental analysis of distribution and abundance. Addison-Wesley, New York, 772. Micu, S., Abaza, V., Changes in biodiversity of Decapods from the Romanian Black Sea coast. Anal. St. Univ. Al.I.Cuza, Iasi, Biologie animala, L: Micu, S., Micu, D., Proposed IUCN regional status of all Crustasea: Decapoda Species from the Romanian Black Sea. Anal. St. Univ. Al.I.Cuza, Iasi, Biologie animala, LII: Stiling, P., Ecology. Theories and Applications. Prentice Hall, New Jersey. Tiganus, V., Fauna associated with the main macrophytae algae from the Romanian Black Sea coast. Cercetari Marine, IRCM, Constanta, 24-25: Udekem, d Acoz, C Inventaire et distribution dec crustaces decapods de l Antique nord-oriental, de la Mediterranee at des eaux continentals adjacentes au nord de 25 N. Patrimones Naturales, 40 : 1-383, Paris. -33-

PROPOSED IUCN REGIONAL STATUS OF ALL CRUSTACEA: DECAPODA FROM THE ROMANIAN BLACK SEA

Analele Ştiinţifice ale Universităţii AL. I. CUZA Iaşi, s. Biologie animală, Tom LII, 2006 PROPOSED IUCN REGIONAL STATUS OF ALL CRUSTACEA: DECAPODA FROM THE ROMANIAN BLACK SEA SANZIANA MICU 1 and DRAGOŞ