Mesozooplankton from Ría de Vigo (NW Spain) and its adjacent shelf between 1995 and 2003

Abstract

The mesozooplankton (200 μm to 2 mm) community from monthly samples collected at two stations in Ría de Vigo (39 m) and its adjacent shelf (97 m) between 1995-2003 is described. The mesozooplankton was dominated by copepods. Inside the Ría, meroplankton (larvae of gasteropods, lamelibranchiae, echinodermate and cirripids nauplii) and other holoplanktonic organisms, such as apendicularia, cladocera, siphonophora and medusae, were also well represented. The copepod group inside the Ría was dominated by Acartia clausi, juveniles of Calanus helgolandicus, Paracalanus parvus, Pseudocalanus elongatus, Temora longicornis, Oithona plumifera, Oncaea media, Euterpina acutifrons and copepodites of Centropages spp. In the offshore station, dominant copepods species were the same than inshore together with other oceanic species, such as Paraeuchaeta hebes, Calanoides carinatus and Aetideus armatus. Biomass values within Ría de Vigo ranged between 2 and 151 mg dry weight /m3 and between 2 and 314 mg dry weight /m3 in the offshore station. Abundance ranged between 149 ind/m in January 1995 and 41814 ind/m3 in August of 2003 in the inner station, and between 22 ind/m3 in January 1996 and 93410 ind/m3 in May 1999 in the outer station. The most outstanding events were the high levels of the Mediterranean copepod Temora stylifera, usually rare in Galician waters recorded in the area in 1997 and 1998, and the increased levels of cirripid larvae observed inside the Ría.