Sado Estuary, Portugal

Fish morphology, age and physiology; Industrial discharges; Fish disease and parasites; Bioassay and contaminant biological impact

Pelagic trawl nets

With this project we aim to assess the suitability of a fish species, Gobius niger Linnaeus 1758, as an indicator of pollution caused by industrial effluent namely from pulp and paper mills. It is of current knowledge that such effluent cause some kind of osteological deformities in fish. In Sado estuary some deformed specimens of Gobius niger were caught. Percentages of deformed fish attained more than 5 per cent or more than 20 per cent according to the type of deformity, vertebrae or ural plates. The existence of various effluent in Sado estuary implies that laboratorial tests are needed to assess precisely the causes of deformities occurrence. Some answers to some questions must be obtained, like the following: - What relation exists between pollutant type and the deformation caused? - The increase in pollutant concentration increases the degree of deformation and/or the frequency of occurrence of deformities? To answer these questions it is necessary to capture specimens in unpolluted areas and to use them in laboratory tests with different pollutant concentrations. After some months specimens would be sacrificed and examined to detect osteological deformities and possible alterations in liver and gill histology. Parasitology, bacteriological and hematological studies will be done also.

National Laboratory of Veterinary Research, Lisbon, Aquatic Animals Biological and Pathological Services
Estrada de Benfica 701
Lisboa
Lisboa
1549-011
Portugal