REPRODUCTION PATTERNS OF THE “SEA PEN” MALACOBELEMNON DAYTONI (OCTOCORALLIA, PENNATULACEA, KOPHOBELEMNIDAE) AT POTTER COVE

SERVETTO, N; LAGGER, C.; ACOSTA, S.; DEMARCHI, M.; WIERNES, P.; TATIÁN, M.; TARANTELLI, S.; SAHADE, R.

Buenos Aires

Congreso; SCAR XXXI & Open Science Conference; 2010

SCAR/DNA

Pennatulaceans, commonly known as sea pens, are colonial anthozoans being the only octocorals adapted to live buried in soft sediments. A typical sea pen consists of a single large, elongated axial polyp. Autozooids and siphonozooids, often forming a leaf-like structure, are distributed in the rachis, the upper part of the colony. The siphonozooids have long cilia and are known to generate currents, whereas autozooids can feed and have the potential to bear gonads. The reproductive biology of Malacobelemnon daytoni was studied in a shallow-water population at Potter Cove, South Shetland Islands (62º14’S, 58º40’O). Sampling was carried out by SCUBA diving at about 10-16m depth every month during 2009. Reproductive cycle was examined by histological analysis. Gametogenesis was continuous year-round, although mature oocytes and mature spermatocytes were mainly observed during the austral winter. Mean oocyte diameter peaked in April and May and showed a sharp decrease in July and August, which suggests a strong seasonality in reproduction. It is interesting that reproduction of this suspension-feeder seems to be decoupled from the pulses of primary production characteristics of Antarctic systems and was not related to temperature changes. It was striking since these two factors are usually among the most important in determining reproductive cycles, especially in suspension-feeders. This suggests either that winter time is not so stressful, in energetic terms, at least in the Potter Cove ecosystem, or that this species is capable to store energy in some organs during favorable periods to later fuel reproduction.