Medium- and long-term temporal trends in the fish assemblage inhabiting a surf zone, analyzed by Bayesian generalized additive models

The present study characterizes the fish assemblage in the surf zone of Cassino Beach, Rio Grande, Brazil, and analyzes temporal fluctuations in richness and abundance of these species in medium (months) and long terms (years), associating them also with abiotic covariates. Data were collected monthly between 1996 and 2012 at two locations. Bayesian generalized additive models (GAMs) were used as statistical tool, placing this study among few that have used Bayesian GAMs in Ecology. Our results show a decrease in both species richness and abundance of the most representative species, over the last 16 years, but no significant distinction between locations. Water temperature and salinity along with seasonality were the statistically most influential explanatory covariates to describe fluctuations in richness and abundance. Higher discharge rates of the three main rivers that flow into Patos Lagoon (Jacuı´, Taquari, Camaqua˜) were associated with increased richness and abundance of some species in the assemblage. Hence, our findings show that medium- and long-term fluctuations in richness and species abundance are controlled by abiotic factors related to seasonal cycles (temperature) and productivity of the ecosystem. Long-term changes seem to be also related to man-induced factors and climate change; but further research is needed

Spatial and temporal scales of environmental forcing of Acartia populations (Copepoda: Calanoida) in the Canal de Mira (Ria de Aveiro, Portugal)

Zooplankton and hydrological data were collected from August 2000 and June 2002 at six stations distributed throughout Canal de Mira (Ria de Aveiro, Portugal). The abundance of Acartia clausi and Acartia tonsa adults and juveniles of Acartia spp. for each station and month were combined in a three-way data matrix, which was decomposed into three two-way matrices corresponding to different modes: biological, time, and space. Cluster analysis applied on the space mode revealed the existence of three different zones as a consequence of zooplankton composition. At each mode, principal component analysis showed strong seasonal variations in zones 1 and 2. A different spatial pattern was found between the periods November 2000–April 2001 and November 2001–April 2002, with the displacement of the highest abundance levels from the middle estuary to near the mouth. The congeneric populations were segregated in space: the A. clausi population was restricted to downstream stations (zone 1), whereas the A. tonsa population dominated the middle estuary. Significant correlations between hydrological parameters and copepod abundance were found to differ from zone to zone. The statistical methodology was a valuable tool to (i) discriminate spatial and seasonal distribution patterns, (ii) define estuarine sections based on the faunistic composition, and (iii) evaluate delayed effects of phytoplankton

Dealing with temporal variation and different life stages of whitemouth croaker Micropogonias furnieri (Actinopterygii, Sciaenidae) in species distribution modeling to improve essential estuarine fish habitat identification

Understanding the habitat usage of a species is essential to assessing the impacts of human activities, conservation efforts, and management issues on that species. Whitemouth croaker, an important species in the artisanal fishery market, inhabits different habitats of the Patos Lagoon estuary year-round based on the stage of its life cycle. Our aim was to test the hypothesis that habitat preferences and changes in abundance during the life cycle influence the model outcomes in the study of species distribution. Additionally, we evaluated whether incorporating additional life stages within the model affected the outcome of what comprised the essential fish habitat. Our results showed that the model’s outcome was affected when temporal variability and additional life stages were considered. We suggest that variability in abundance and habitat preferences at different developmental stages must be considered when identifying essential fish habitat of species with complex life cycles, such as whitemouth croaker. Understanding these changes could improve conservation and management outcomes