The community structure of phytoplankton as indicator of coastal water quality in the tourist area

Abstract

An annual evaluation (June 1994-July 1995) of the water quality from Punta de Tenefé to Punta de Taozo (Gran Canaria, Canary Islands) was done, as a part of an environmental assessment program in tourist coast. The ecological parameters to evaluate were chosen as representative of the hurnan pressure exerted on the coast (crowded beaches, direct wastewater falls or ernissaries, marinas) and were: qualitative and quantitative analysis of phytoplankton community structures, biomass and nutrients. The aim was to characterize the conflictive points as regard to seasonality, climatology and oceanographic conditions. The phytoplankton (biomass and species) negatively correlated to nutrient species, particularly to silicate which decree as increased diatoms. Maximum biomass was observed by March when Rhizosoleniastolteforthii, R setigera, Chaetoceros decipiens y Ch. debilis proliferated. Cosmopolitan species such as Nitzchia closterium. N seriata, Navicula sp.. Fragilaria sp., Licrnophora sp among others were always present. In spite of being scarce compared to diatoms; Dinoflagellate representatives Protoperidiniurn sp., Ceratium sp. and C. furca increased by summer. Gonyaulax sp., indicator-species of chemical and physical alterations, was observed in samples from stations located near underwater emissary exits.