title: Effects of pollution on zooplankton abundance and distribution in two estuaries of the Basque coast (Bay of Biscay).
abstract: The abundance and spatial distribution of mesozooplankton were compared in the euhaline region of the polluted Bilbao estuary and the unperturbed Urdaibai estuary. The environmental variables measured were salinity, temperature, dissolved oxygen saturation, chlorophyll a, particulate organic matter and Secchi disk depth. Differences in the environmental variables and zooplankton between the estuaries and within the estuaries were tested statistically. Differences in the patterns of mesozooplankton abundance with salinity in each estuary indicated that they were affected by pollution in the Bilbao. Total mesozooplankton, and several mesozooplankton categories were more abundant in the Bilbao at higher salinities but in the Urdaibai at lower salinities. Therefore, we deduced that, in the Bilbao, zooplankton abundance was enhanced by the moderate pollution at the outer euhaline zone and limited by the poorer conditions of the inner zone. The response of the various zooplankton categories to the pollution is discussed.
authors.affiliation: Laboratory of Ecology, Department of Plant Biology and Ecology, Faculty of Sciences, University of the Basque Country, 644 P.K. E-48008 Bilbao, Spain.
authors.forename: Ibon
authors.initials: I
authors.lastname: Uriarte
authors.forename: Fernando
authors.initials: F
authors.lastname: Villate
mesh_terms: D000818:Animals; D017753:Ecosystem; D004784:Environmental Monitoring; D011157:Population Dynamics; D012623:Seawater / Q000737:chemistry; D012965:Sodium Chloride; D013030:Spain; D014873:Water Pollutants / Q000506:poisoning*; D014881:Water Supply; D015048:Zooplankton
chemical_list: D014873:Water Pollutants; D012965:Sodium Chloride