Fish fauna as an indicator of environmental quality in an urbanised region of the Amazon estuary

Abstract

This study describes the biological importance of Guajará Bay (Belém, Pará, Brazil) for fish fauna and presents a diagnosis of water quality in the main channel and creeks, using the icthyofauna as an ecological indicator. A total of 567 individuals from 40 species were identified. About 58% of these use Guajará Bay as a nursery ground, 49 and 81% use the bay as a breeding and feeding ground, respectively. There were no significant differences between environments as measured by the diversity index; however, fish relative abundance (catch per unit of effort) was greater in the creeks than in the main channel. A significant difference was detected in the fish fauna inhabiting the main channel compared with the creeks. In the main channel, icthyofauna significantly differed during December relative to other months.

Spatio-temporal distribution of fish larvae in relation to ontogeny and water quality in the oligohaline zone of a North Brazilian estuary

“…The time frame for fish reproduction in tropical countries matches either a peak in natural food production (Cushing 1990) or propitious weather conditions that enhance recruitment success (Sinclair & Tremblay 1984). The main reproduction period at the onset of the rainy season (Viana et al 2010, present study) when levels of primary production are high (Paiva et al 2006), supports the first affirmation. According to Paiva et al (2006), the high quantity of sediment load transported by the Guamá River during the rainy season increases water turbidity which, in return, inhibits phytoplankton growth.…”

“…Coser et al 2007), did not allow cross-checking this information with the ichthyoplanktonic data. The absence of Pristigasteridae larvae contrasted with the relatively strong abundance of the adults individuals (Viana et al 2010), suggesting that their main spawning ground is not in the area of study. It is however noted that a few larvae of this family were encountered in small, highly contaminated creeks of the capital city during the months of September and January (V. Sarpedonti, unpublished data).…”

“…It is however noted that a few larvae of this family were encountered in small, highly contaminated creeks of the capital city during the months of September and January (V. Sarpedonti, unpublished data). Discrepancies between adults (Viana et al 2010) and larvae (this study) encounters in the bay were also registered among nonclupeiforms and attributed to habitat specificity or reproduction strategy. For example, adults Colomesus asellus (Müller & Troschel, 1849 -Tetraodontidae) and Curimata inornata (Vari, 1989 -Curimatidae) used the bay as a breeding ground; however, as they occupy essentially small channels, their larvae were absent from the bay samples (this study) but were found in nearby mangrove environments (Sarpedonti et al 2008) and small creeks of Belém's Islands (V. Sarpedonti, unpublished data).…”

“…As they reach a more advanced development stage, the individuals move towards areas of stronger water flow and use the currents to reach other nursery grounds (Baumgartner et al 2003, Bialetzki et al 2004. All the remaining larval species that were absent from the juvenile/adult catches (Viana et al 2010) counted very few individuals suggesting that their presence was accidental or that Guajará Bay was on their migration route. The time frame for fish reproduction in tropical countries matches either a peak in natural food production (Cushing 1990) or propitious weather conditions that enhance recruitment success (Sinclair & Tremblay 1984).…”

“…3 worldwide estuaries (Barletta-Bergan et al 2002a, Bonecker et al 2007). Studies on the adults' gonad maturation stages indicated that the widely distributed euryhaline engraulid Anchoa spinifer (Valenciennes, 1848) predominantly used Guajará Bay as a breeding ground (Viana et al 2010). However, difficulties faced to identify clupeiform larvae up to the species level as it is often the case (e.g.…”