The use of nursery areas by juvenile fish in a temperate estuary, Portugal

Abstract

The nursery role of the Mondego estuary for marine fish species was studied between June 2003 and May 2004. The spatial and temporal distribution and abundance patterns of 0-group Dicentrarchus labrax (Linnaeus, 1758), Platichthys flesus (Linnaeus, 1758) and Solea solea (Linnaeus, 1758) were analyzed based on monthly sampling surveys in five stations along the estuarine gradient. Fishing took place during the night at low water of spring tides, using a 2 m beam trawl. The spatial patterns of estuarine colonization were different according to species. D. labrax showed a wider distribution, but the main nursery ground was the same as for S. solea. Highest densities of S. solea juveniles were found in oligohaline areas, with muddy bottoms and high benthic invertebrates availability, while P. flesus occurred mainly in the sandy uppermost areas. D. labrax was found in both these areas. Fish abundance in the estuary mainly reflected seasonal changes.

Toxicity of dispersant application: Biomarkers responses in gills of juvenile golden grey mullet (Liza aurata)

“…This 62 environmental precautionary principle is based (i) on the low dilution potential of the oil slick 63 in the shallow waters of nearshore areas and (ii) on the ecological sensitivity of nearshore 64 areas since they are nurseries for many fish species (Martinho et al, 2007). On the other hand, 65 a field study conducted by Baca et al (2006), but only applicable to nearshore mangroves, 66 seagrass and coral ecosystems, revealed a positive net environmental benefit of dispersant 67 application in nearshore areas.…”

Estuarine production of resident and nursery fish species: Conditioning by drought events?

“…Estuarine systems are extremely valuable for many marine fish species of the continental shelf, by providing important nursery grounds Martinho et al, 2007a;Nicolas et al, 2007), as well as for several other fishes, such as the resident ones, spending their complete life cycle within the estuary (Elliott and Dewailly, 1995;Dolbeth et al, 2007a). Frequently, these two ecological fish guilds (marine juvenile and resident) represent the major part of the fish community found in estuarine systems (Elliott and Dewailly, 1995;Martinho et al, 2007b).…”

“…The juvenile growth and survival of the marine species, hence recruitment into adult populations, and the maintenance of the resident species within the estuarine ecosystem are greatly determined by its environmental quality, regarding both anthropogenic stress and natural variability (Nicolas et al, 2007). The availability of essential habitats (such as seagrasses and saltmarshes), providing protection from predators, and their great production, providing abundant food supplies, are considered as major determinants for fishes in estuaries (Beck et al, 2001;Cabral et al, 2007;Martinho et al, 2007a). Several of the marine juvenile fishes that occur in estuaries are commercially important, hence estuaries may be considered as essential ecosystems for the renewal of fisheries resources, acquiring also a direct relevant economic value for mankind (Houde and Rutherford, 1993;Cowley and Whitfield, 2002;Able, 2005;Nicolas et al, 2007).…”

The influence of an extreme drought event in the fish community of a southern Europe temperate estuary

“…Previous works regarding the Mondego Estuary fish community focused mainly on the structure according to the ecological guilds previously referenced and also on the importance of the estuary as a nursery area for commercial marine species (for further details see Jorge et al, 2002;Leitão et al, 2006Leitão et al, , 2007Martinho et al, 2007). As a general trend, in the last 15 years a major decline in species number from 1989e1992 to 2003/2004 was noticed, mostly freshwater species .…”