PHYTOPLANKTON BIOMASS AND ZOOPLANKTON ABUNDANCE ON THE SOUTH COAST OFPORTUGAL (SAGRES), WITH SPECIAL REFERENCE TO SPAWNING OF LOLIGO-VULGARIS

The importance of the south-west coast of Portugal as a spawning groun d for the long-finned squid, Loligo vulgaris, was investigated between May 1993 and May 1994 at a site 3 Km East of Sagres. Hydrographic (te mperature and salinity) observations were registered in situ and water samples were collected for laboratory determinations of chlorophyll a . Zooplankton was sampled with a 500 mu m plankton net during 10mn tra wls. Hydrographic and biological information was related to the occurr ence of L. vulgaris egg masses at the site. The values of water temper ature ranged from 13.0 degrees C in January to 19.2 degrees C in July, and the salinity varied between 35.3 parts per thousand in May of 199 3 and 38.0 parts per thousand, in November, December and March. The hi ghest values for phytoplankton biomass were recorded in September and May, whereas the maximum zooplankton abundance was recorded between Ju ly and September. The most important zooplankton groups included clado cerans, copepods, crustacean larvae, fish eggs and appendicularians. W e have concluded that the highest values for zooplankton abundance wer e recorded when the greater number of egg masses of L. vulgaris were o bserved.