Spatiotemporal variation among demersal ichthyofauna in a subtropical estuary bordering World Heritage-listed and marine protected areas: implications for resource management

Abstract

Benthic trawl surveys were performed to quantify the spatiotemporal distributions of teleosts and key abiotic associations throughout an ecologically important estuary within Brazil's Atlantic Forest biosphere. Approximately 52 000 fish (51% juveniles) representing 75 species were sampled, with residents accounting for 36 and 61% of total species and individuals respectively. Five artisanally important species comprised 77 and 81% of individuals and biomass respectively. Cathorops spixii was most abundant (.40% of total), whereas Stellifer rastrifer, Aspistor luniscutis, Sphoeroides greeleyi and S. testudineus collectively contributed towards 37 and 34% of individuals and biomass respectively. The abundance of A. luniscutis, C. spixii and S. rastrifer was negatively associated with salinity, whereas the presence of the latter two species was also positively associated with temperature, and S. greeleyi and S. testudineus (mostly adults) were more abundant in deeper areas. These relationships seemed to be affected by species-specific reproductive (S. rastrifer, C. spixii and A. luniscutis), habitat (S. greeleyi and S. testudineus) and prey preferences (juvenile C. spixii and A. luniscutis). Protection for these various species may be achieved via immediate fishing effort regulations, but more research is required to manage other anthropogenic effects. Such work should be a priority to ultimately preserve what is one of the most important South American biodiversity areas.

Seasonal and environmental influences on recruitment patterns and habitat usage among resident and transient fishes in a World Heritage Site subtropical estuary

“…This study is among the first to comprehensively assess the recruitment patterns of resident and transient ichthyofauna in the PEC across broad temporal scales in two divergent areas subjected to distinct oceanographic patterns, and to isolate some key associated environmental factors (Pichler et al ., ; Possatto et al ., ). In doing so, the work not only contributes towards the information from other regional studies (Barletta et al ., ; Contente et al ., ; Passos et al ., , ; Possatto et al ., ), but also the broader primary literature describing such processes in subtropical estuaries, ultimately improving understanding of these systems for management (Blaber & Barletta, ).…”

“…At a smaller scale within both bays, the recruitment of demersal and pelagic fishes (indicated by greatest mean numbers) primarily occurred in the polyhaline zone during the wet season. The greatest species richness also occurred in both bays during the wet season, although often many fishes were only present in low abundances and typically transient recruits of marine origin, which supports the general supposition that the wet season is the dominant recruitment season even for marine species that only utilize estuaries during their early development (Pichler et al ., ; Possatto et al ., ). More specifically, Blaber () described spawning peaks just prior to the wet season and, in subtropical estuaries, reproductive activity coinciding with even small increases in water temperature.…”

“…Irrespective of the divergent hydrological processes between bays, the distributions of fish guilds–recruits were similarly affected by seasonal influences (especially rainfall and salinity), which corroborates observations by Possatto et al . () of fishes in deeper sublittoral waters of the PEC. Specifically, the sampling restriction to mesohaline and polyhaline sites was reflected in the observed assemblage compositions in both bays, with only two freshwater species ( P. vivipara and G. brasiliensis ) caught (in Guaraqueçaba Bay).…”

“…Alternatively, because salinity and temperature strongly determine fish assemblage structure and distribution, some associated temporal differences in the distributions and abundances of resident and transient recruits might be expected. Such questions underscore the need to delineate clear periods of maximum habitat use by juvenile fishes for their effective management and conservation, especially in subtropical regions, which often have the largest extremes in rainfall and salinity, and in many developing regions concomitant high artisanal fishing effort involving small‐meshed, poorly selective gears (Pichler et al ., ; Possatto et al ., ).…”

Ichthyofauna of the inner shelf of Paraná, Brazil: checklist, geographic distribution, economic importance and conservation status

“…There have been several studies on the fish fauna in the Paranaguá Estuarine Complex (Hackradt et al 2009;Félix-Hackradt et al 2010;Ignácio & Spach 2010;Contente et al 2011;Passos et al 2012;Pichler et al 2015Pichler et al , 2017Possatto et al 2017) and in the Guaratuba Bay (Chaves & Corrêa 1998;Chaves & Vendel 2001). On the other hand, few studies have focused on the continental shelf region, especially those assessing the taxonomic composition of the ichthyofauna (Santos 2006;Carniel 2008;Schwarz-Junior 2010).…”