Migratory fish larvae in the Amazon River: implications for conservation and sustainability of fishery resources
Keywords:
Characiformes, Amazon river, Floodplain, Reproductive strategyAbstract
The present work analyzed the variation of abundance in the temporal and spatial distribution of larvae of three fish species of economic and subsistence interest in the Lower Amazon region: Mylossoma albiscopum (Cuvier, 1818), Potamorhina altamazonica (Cope, 1878) and Triportheus auritus. (Valenciennes 1850), aiming to provide information on the importance of the studied environment as a natural breeding area for these ecologically important and abundant species in the lakes and rivers of white waters of the Amazon region and much appreciated by the riverside population. The collections were carried out monthly from January to December 2013, by means of a 300µm mesh plankton net, in horizontal trawls in the subsurface of the water column, and simultaneously with the collection of biological material environmental variables (pH, temperature, dissolved oxygen and electrical conductivity) were measured. In the laboratory, the samples were sorted, the larvae quantified and identified. Significant differences in larval density were detected between months for M. albiscopum (ANOVA; F = 28.79; p = <0.01), P. altamazonica (F=15.53; p = <0.01) and T. auritus (F = 5.90; P = <0.01). Species were not evenly distributed throughout the collection seasons. However, no significant differences (p> 0.05) were observed in the spatial variation of larval density. In addition, the analysis summarized by the non-metric multidimensional scaling (NMDS) showed that the distribution of larvae at all collection points and the absence of clustering in relation to sampling stations in contrast to the clustering of the months with the highest rainfall, demonstrated the importance of periodically flooded areas for the ichthyofauna and showed that all the physiographies present in the studied area, such as areas near coves, ravines and restingas are relevant in the initial development of these species, either as dispersal or colonization area. The electrical conductivity presented significant correlation with the density of the three studied species. Therefore, conservation is a priority action to maintain sustainability, maximizing the growth and recruitment of these fish species in the Lower Amazon region (PA).
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