Proceedings of the Second Mediterranean Symposium on Marine
Proceedings of the Second Mediterranean Symposium on Marine
Proceedings of the Second Mediterranean Symposium on Marine
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PROCEEDINGS OF THE SECOND MEDITERRANEAN SYMPOSIUM ON MARINE VEGETATION (ATHENS, 12-13 DECEMBER 2003)<br />
244<br />
PRELIMINARY RESULTS OF THE EPIBIOTIC FLORA<br />
ON EUNICELLA SINGULARIS (GORGONACEA) COLONIES<br />
FROM THE NORTH AEGEAN SEA<br />
George SKOUFAS 1 & Anastasia TSIRIKA 2<br />
1 Technological Educati<strong>on</strong>al Institute <str<strong>on</strong>g>of</str<strong>on</strong>g> Thessal<strong>on</strong>iki, Department <str<strong>on</strong>g>of</str<strong>on</strong>g> Fisheries Technology and Aquacultures, N. Miltiadi 1, GR- 623<br />
00, Nea Moudania, Greece<br />
2 Aristotle University <str<strong>on</strong>g>of</str<strong>on</strong>g> Thessal<strong>on</strong>iki, Department <str<strong>on</strong>g>of</str<strong>on</strong>g> Biology, Institute <str<strong>on</strong>g>of</str<strong>on</strong>g> Botany, GR- 541 24, Thessal<strong>on</strong>iki, GREECE<br />
ABSTRACT<br />
The gorg<strong>on</strong>ian branches denudati<strong>on</strong> is described as necrosis. Gorg<strong>on</strong>ian necrosis<br />
phenomena have been observed in tropical seas, as well as in <str<strong>on</strong>g>the</str<strong>on</strong>g> <str<strong>on</strong>g>Mediterranean</str<strong>on</strong>g> Sea.<br />
The denuded gorg<strong>on</strong>ian branches <str<strong>on</strong>g>of</str<strong>on</strong>g>fer an important hard substrate for <str<strong>on</strong>g>the</str<strong>on</strong>g> installati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
a very rich epibiotic fauna and flora. However, gorg<strong>on</strong>ian epibi<strong>on</strong>ts change<br />
hydrodynamical properties <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> axis and water currents can uproot <str<strong>on</strong>g>the</str<strong>on</strong>g> col<strong>on</strong>ies.<br />
Although <str<strong>on</strong>g>the</str<strong>on</strong>g> existence <str<strong>on</strong>g>of</str<strong>on</strong>g> epibiotic algae <strong>on</strong> denuded gorg<strong>on</strong>ian branches has been<br />
recorded in <str<strong>on</strong>g>the</str<strong>on</strong>g> <str<strong>on</strong>g>Mediterranean</str<strong>on</strong>g> Sea, almost no data <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> identity <str<strong>on</strong>g>of</str<strong>on</strong>g> those macroalgae<br />
species have been given. The aim <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> present study is to report <str<strong>on</strong>g>the</str<strong>on</strong>g> dominant<br />
macroalgae species installed <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> col<strong>on</strong>ies <str<strong>on</strong>g>of</str<strong>on</strong>g> a Eunicella singularis gorg<strong>on</strong>ian<br />
populati<strong>on</strong> that presented a mass mortality phenomen<strong>on</strong> in Arethoussa (Kavala bay,<br />
North Aegean Sea). The examined Eunicella singularis populati<strong>on</strong> expanded at a depth<br />
range between 5 and 15 meters. In situ observati<strong>on</strong>s at 350 gorg<strong>on</strong>ian col<strong>on</strong>ies showed<br />
that 342 (97.7%) col<strong>on</strong>ies were affected by partial or total necrosis. Total necrosis and<br />
coverage <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> denuded branches by epibiotic algae exhibited 287 (82%) col<strong>on</strong>ies. In<br />
additi<strong>on</strong>, 55 (15.7%) col<strong>on</strong>ies presented partial mortality and exhibited both denuded<br />
and not denuded branches. Only 8 col<strong>on</strong>ies from <str<strong>on</strong>g>the</str<strong>on</strong>g> investigated gorg<strong>on</strong>ian populati<strong>on</strong><br />
exhibited no mortality spots. Seas<strong>on</strong>al samples <str<strong>on</strong>g>of</str<strong>on</strong>g> approximately 15 col<strong>on</strong>ies were<br />
collected with SCUBA-diving during 1997. The investigati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> epibiotic algae<br />
exhibited significant seas<strong>on</strong>al variati<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> algae wet weight and algae coverage. The<br />
maximum <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> algae wet weight was observed in spring and <str<strong>on</strong>g>the</str<strong>on</strong>g> maximum <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> algae<br />
coverage during <str<strong>on</strong>g>the</str<strong>on</strong>g> summer. Fur<str<strong>on</strong>g>the</str<strong>on</strong>g>rmore, it was observed that <str<strong>on</strong>g>the</str<strong>on</strong>g> algae surface was<br />
remarkably bigger than <str<strong>on</strong>g>the</str<strong>on</strong>g> surface <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> denuded gorg<strong>on</strong>ian branches. The above algae<br />
features displayed a significant spearman correlati<strong>on</strong> to <str<strong>on</strong>g>the</str<strong>on</strong>g> biometric parameters <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g><br />
denuded branches. The dominant macroalgae species installed <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> denuded<br />
branches were <str<strong>on</strong>g>the</str<strong>on</strong>g> red algae Womersleyella setacea, Botryocladia botryoides, Fauchea<br />
repens and <str<strong>on</strong>g>the</str<strong>on</strong>g> brown algae Sphacelaria plumula, Dictyopteris polypodioides, Dictyota<br />
dichotoma, Halopteris filicina, Stypocaul<strong>on</strong> scoparium and Zanardinia typus. The red<br />
alga Falkenbergia rufolanosa (tetrasporophyte <str<strong>on</strong>g>of</str<strong>on</strong>g> Asparagopsis armata) was found as<br />
an epiphyte <strong>on</strong> Womersleyella setacea in all <str<strong>on</strong>g>the</str<strong>on</strong>g> seas<strong>on</strong>s being remarkably abundant in<br />
winter. Ano<str<strong>on</strong>g>the</str<strong>on</strong>g>r red alga, growing as an epiphyte and being recorded for <str<strong>on</strong>g>the</str<strong>on</strong>g> first time at<br />
Greek coasts in <str<strong>on</strong>g>the</str<strong>on</strong>g> present study, was Trailliella intricata (tetrasporophyte <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
B<strong>on</strong>nemais<strong>on</strong>ia hamifera). This filamentous species was present throughout <str<strong>on</strong>g>the</str<strong>on</strong>g> year,<br />
forming dense tufts (up to 15 mm in diameter), <strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> brown alga Dictyopteris<br />
polypodioides.