Epiphytic Bryozoa of Posidonia oceanica leaves and scales

Study Extent

All sampling and measurements were performed at Revellata Bay (Calvi, Corsica, France), near the marine research centre of STARESO (42°35’N-8°43’E) (University of Liège).

Sampling

Seagrass shoots were collected in triplicate in November 2002, March, June, September and November 2003 along the same permanent transects set at 7, 10, 15, 20, 25 and 30 m depth. Colonies counted (see above) were reported per meter square, accounting the average P. oceanica shoot density measured at each sampling depth. Shoot density, measured monthly using a quadrate with an area of 0.1 m2 randomly set in the meadow.

Quality Control

Identifications under stereomicroscope (Stemi 2000, Zeiss) were done to the lowest systematic level using keys for Bryozoa (Prenant & Bobin, 1966; Zabala & Maluquer, 1988), and the works of Hayward & McKinney (2002), Gautier (1961) or Balduzzi et al. (1991). All the colonies found on the two sides of leaves were counted. Colony on scales were not counted because dissection of scales (i.e. old leaf petioles remaining on rhizomes after limb abcission) involved colony fragmentation. Each sample is constituted of a single replicate gathering 3 shoots of P. oceanica. For Electra posidoniae, colonies fusion (or apparent fusion) is common. Therefore for this species, as a proxy of the colonies counted, the number of colonies founders (i.e. ancestrulae), which have a distinctive morphology, was counted.

Method steps

1. This study involved the monthly assessment of colonization dynamics, biomass seasonality, and diet composition through measurements of stable isotopes, in E. posidoniae at a depth of 10 m in the Revellata Bay (Corsica, Mediterranean Sea).

Bryozoa, Gymnolaemata, Cheilostomata

1. Bryozoa
   common name: moss animals rank: phylum
2. Gymnolaemata
   rank: class
3. Cheilostomata
   rank: order

Revellata Bay (Corsica, Mediterranean Sea)(a part of the Gulf of Calvi)