Climate extremes, such as drought and floods, are increasing and should be considered in ecosystem management plans. The effects of an extreme drought were studied in two estuaries of the Iberian coast, Minho and Mondego, by exploring fish recruitment, growth and production over four years. The two estuaries are located within an area with transitional climate, and differ considerably in size, availability of freshwater wetlands and freshwater inflow. Fishes from the Minho estuary, at higher latitude, generally had lower growth rates and later timing of recruitment. During the drought, freshwater inflow was severely reduced in both estuaries. The overall fish assemblage production in the Minho estuary decreased considerably, whereas in the Mondego estuary it showed an increase. However, the drought effects seemed highly species‐specific and dependent on local geomorphology; the increase in the Mondego estuary was a result of an increase in a single species, whereas other species decreased or maintained similar production levels. Decreases in production in both estuaries were attributed to direct and indirect effects of changes in the freshwater inflow during the study period. This parameter should therefore be considered when undertaking management plans for transitional waters.
Impact of eutrophication on amphipods Melita palmata and Ampithoe valida in the Mondego estuary