Seasonal changes in fish assemblages in the River Minho tidal freshwater wetlands, NW of the Iberian Peninsula

Abstract

-The ichthyofauna of the River Minho tidal freshwater wetlands (TFWs) was studied in a semienclosed area, between June 2007 and May 2010, to determine temporal patterns of abundance, biomass and species composition. Fish catches, standardized by the number of fyke nets and by the fishing effort, were analysed and related to river flow, water temperature and precipitation. In total, 21 fish species were identified including six non-indigenous species (NIS) which represented 15% of the total captures (yet 43% of the biomass). Regarding ecological guilds, 82% were freshwater species (61% of the biomass) which included all NIS, whereas 13% of the catches were catadromous species (31% biomass) corresponding to eels. Only 4% were estuarine species (1% biomass) and together marine estuarine opportunists and anadromous species accomplished 1% (2 and 6% biomass, respectively). The fish assemblage showed seasonal patterns with a clear distinction between autumn/winter and spring/summer periods. Significant differences in abundance and biomass were also detected between autumn/winter of 2007/2008 and 2008/2009, i.e., inter-annual variations, with the latter period with lower catches yet higher dominance of NIS. Besides, higher water temperature had a significant negative effect on the observed number of species, but a positive effect on the abundance and biomass of NIS. More attention has to be given to TFWs and their role in structuring fish assemblages, because this information is vital for a sound management, conservation and restoration of estuarine areas.

Effects of intrapopulation phenotypic traits of invasive crayfish on leaf litter processing

“…Specimens were collected in a semi-enclosed area (depth variation between 1.5 and 3.0 m and 14 km upstream of the river mouth). A full description of the abiotic and biotic conditions of the collection site can be found in Sousa et al (2013) and Mota et al (2014). Crayfish were captured with fyke-nets (10-mm mesh, 0.7-mdiameter mouth, 7-m-long, 3.5-m central wing) during their active period (May and June 2013) as described in Sousa et al (2013).…”

A comparison of temperature regimes in dry-season waterholes in the Flinders and Gilbert catchments in northern Australia

“…These occur in arid zones around the world and provide vital habitat for the survival of aquatic biota (Larned et al 2010;Lake 2011;Datry et al 2014;Mota et al 2014). Depending on the severity and duration of the dry season, waterholes may or may not persist (McJannet et al 2014), and even those that do may become isolated and of poor water quality due to high temperatures or low dissolved oxygen (Lake 2011).…”

Palatability of the Asian clam Corbicula fluminea (Müller 1774) in an invaded system

“…The field experiment was conducted near the Praia da Lenta, a semi-enclosed area located 14 km upstream the river mouth. This site was chosen due to its biotic and abiotic conditions that are well known (Mota et al, 2014), and by the fact that C. fluminea occurs under high densities (Sousa et al, 2008a). The study area comprises sandy and muddy habitats heavily covered by submerged vegetation that is composed mainly by the invasive species Egeria densa.…”

“…The study area comprises sandy and muddy habitats heavily covered by submerged vegetation that is composed mainly by the invasive species Egeria densa. In the last 8 years fyke nets have been deployed in this area in order to characterize the fish and crustacean fauna (for details see Sousa et al, 2013 andMota et al, 2014).…”