J. M. Gili

Benthic diatoms as the major food source in the sub-Antarctic marine hydroid Silicularia rosea

Analysis of the gut contents and scanning electron microscopy examination of the benthic hydroidSilicularia rosea from intertidal communities of Potter Cove (King George Island, South Shetlands) suggest that diatoms are the principal source of food for this species. The great number of items captured daily by each polyp (a mean of 287 in January and 162 in December) and the benthic origin of these prey items suggest an adaptation to daily resuspension processes caused by tidal currents. This is an unusual trophic strategy for a benthic hydroid, which would result in an important degree of independence from the highly fluctuating planktonic food conditions in Antarctic waters.

Unjustifiably Ignored: Reflections on the Role of Benthos in Marine Ecosystems

The benthos is not highly regarded by most marine biologists. As a consequence, the in the past most funds have gone into pelagic research, despite the fact that the marine benthos has several properties which render its investigation particularly rewarding. It is far richer in species than is the water column. In addition due to the comparatively low mobility and longevity of many organisms which gives relative persistent assemblages, the behtos is far more suited for monitoring environmental conditions than the ephemeral associations that characterize a certain water body. However, on the rare occasions that benthic research was included in major international programmes, this was usually justified by the role as a temporary or final store for material sedimenting from the water column.

Benthic hydroids (Cnidaria, Hydrozoa) from off Bouvet Island (Antarctic Ocean)

Twenty-seven species of benthic hydroids have been found in a small collection from off Bouvet Island (Antarctic Ocean). The material was obtained during the XXI/2 German Antarctic expedition with R.V. Polarstern 2003–2004. Of the 27 species collected, 21 were unknown from those waters. Consequently, the number of known species of benthic hydroids from the area has risen to 32, representing a high diversity location for this group in the Southern Ocean considering the sampling effort made. All species, including those previously known from Bouvet waters, are considered with respect to geographical distribution.

Les comunitats de coralls al canó de cap de Creus

En la darrera decada, les comunitats de coralls blancs han despertat l’interes dels cientifics a nivell mundial a causa, en part a la seva rellevancia ecologica i en part a la seva desconeixenca. Els escrits antics, des d’inicis del segle XX se sap que aquestes comunitats eren molt abundants en el limit de la plataforma continental a la Mediterrania entre 150 i 400 m de fondaria. Actualment estan confinats a indrets on les activitats pesqueres de rossec no les hagin malmes i es urgent trobar i avaluar el seu estat per promoure la seva conservacio.Un dels indretsmes on es pot confirmar la presencia i bon estat de conservacio en la Mediterrania es el cano submari de cap de Creus. Sobretot a la paret del sud del cano s’han pogut estudiar poblacions molt importants del corall Madrepora oculata i algunes petites poblacions de Lophelia pertusa. Les colonies d’aquests coralls configuren un habitat singular i de gran diversitat resultat, en part, de l’elevada produccio biologica de l’area del cap de Creus i tambe perque la seva localitzacio a la paret del cano ha dificultat la destruccio encara que avui en dia les linies de palangre son l’amenaca mes directa per a la seva supervivencia.