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Species distribution modeling helps understand how environmental factors influence species distribution, creating profiles to predict presence in unexplored areas and assess ecological impacts. This study examined the habitat use and population ecology of the Chilean dolphin in Seno Skyring, Chilean Patagonia. We used three models-random forest (RF), generalized linear model (GLM), and artificial neural network (ANN)-to predict dolphin distribution based on environmental and biotic data like water temperature, salinity, and fish farm density. Our research has determined that the RF model is the most precise tool for predicting the habitat preferences of Chilean dolphins. The results indicate that these dolphins are primarily located within six kilometers of the coast, strongly correlating with areas featuring numerous fish farms, sheltered waters close to the shore with river inputs, and shallow productive zones. This suggests a potential association between dolphin presence and fish-farming activities. These findings can guide targeted conservation measures, such as regulating fish-farming practices and protecting vital coastal areas to improve the survival prospects of the Chilean dolphin. Given the extensive fish-farming industry in Chile, this research highlights the need for greater knowledge and comprehensive conservation efforts to ensure the species' long-term survival. By understanding and mitigating the impacts of fish farming and other human activities, we can better protect the habitat and well-being of Chilean dolphins.

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The pelagic cephalopod species jumbo flying squid Dosidicus gigas is ecologically and economically important in the Humboldt ecosystem off Peru. This squid species is sensitive to oceanic environmental changes, and regional oceanographical variability is one of the important factors driving its redistribution. Off Peruvian waters, mesoscale eddies are ubiquitous and dominate the biogeochemical processes in this region. This study first explored the role of mesoscale eddies in regulating the environments and their effects on the abundance and habitat distribution of D. gigas off Peru by analyzing squid distribution in eddy-centric coordinates and building a habitat suitability index (HSI) model. Results indicated that the abundance and habitat distribution of D. gigas in mesoscale eddies varied across months, with significant differences observed between anticyclonic eddies (AE) and cyclonic eddies (CE). In AE, a higher abundance and proportion of suitable habitat occurred. While in CE, the abundance was relatively low and the suitable habitat was relatively less, concentrating at the periphery of CE. Based on the HSI model results, sea surface temperature (SST) and 50 m water temperature (T50m) in AE were more favorable for D. gigas, which was 0.3-0.5 °C lower than that in CE, yielding high-quality habitats and higher abundance of D. gigas. Our findings emphasized that mesoscale eddies have a significant impact on water temperature conditions and nutrient concentrations off Peruvian waters.

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This paper aimed to estimate the environmental flow of a water basin located in the Brazilian Cerrado using the bidimensional model River2D. The study was carried out in a stretch of the lower portion of the River Ondas in the western part of the state of Bahia, Brazil. To carry out the ecohydrological modeling, the following were used: topobathymetry, hydraulic characterization, the streamflows with the probability of non-exceedances (Q50, Q60, Q70, Q80, Q90, and Q95), and the Habitat Suitability Index for species of the genus Hypostomus. In the River2D, the weighted usable areas (WUAs) pertaining to the streamflows associated with different non-exceedances were simulated for the later construction of optimization and identification matrices of the streamflows that maximize the habitat area throughout the year. For juvenile Hypostomus, WUA increased as streamflow increased, with higher values associated with Q50. For adult specimens, lower WUA values were observed associated with Q50, while higher values were associated with Q95, which shows a preference for lower streamflows. The environmental flows found for the stretch of the River Ondas varied over the course of the year. The lowest environmental flows were observed in September (30.31 m(3) s(-1)) and October (29.98 m(3) s(-1)), while the highest were observed in February (44.22 m(3) s(-1)) and March (43.16 m(3) s(-1)). The environmental flow regime obtained restricts the water availability in the basin, for the purpose of water capture, which shows the importance of ecohydrological studies in forming a basis for water resource management actions.

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The physical habitat simulation sub-routine of the Instream Flow Incremental Methodology (IFIM) uses hydraulic modeling and suitability indices of target fish species to predict how differences in-stream flows affect the microhabitat occupation by fish species. This habitat modelling approach was adopted to assess the ecological effects of running flows on three neotropical fish species of different orders (Bryconamericus ornaticeps , Ancistrus multispinis and Geophagus brasiliensis ).The study encompassed two reaches of an Atlantic Forest stream in Southeastern Brazil where topographic and hydraulic (depth, velocity and type of substrate) characteristics were measured to implement one-dimensional hydraulic simulation. Sub aquatic observation of fish was performed to collect data on microhabitat use and these data were used to develop habitat suitability curves that were used in the habitat simulation to obtain the habitat suitability index (HSI) and weighted usable area (WUA) versus flow curves. Upon these curves minimum and optimum environmental flows for the target fish species were proposed. Bryconamericus ornaticeps and A. multispinis selected microhabitats around 0.6 m depth, whereas G. brasiliensis showed a wider suitable range (0.35-0.9 m). All the three species were mainly observed in microhabitat with low flow velocity (0.1 m/s). Bryconamericus ornaticeps selected more frequently coarse substrate (e.g. boulders) but it appeared also over sandy substrate, whereas A. multispinis and G. brasiliensis selected preferably boulders. The range of 0.65-0.85 m3/s was found as the optimum to meet the needs of the three fish species. Our results agree with the necessary objective information to perform grounded management actions in the frame of a management program aiming at ecosystem conservation. Thereby it can be considered a successful pilot study in environmental flow assessment in an Atlantic Forest stream of Brazil.(AU)

A sub-rotina simulação de habitat físico da metodologia incremental - IFIM usa variáveis hidráulicas e os índices de aptidão das espécies alvo para predizer como diferentes vazões afetam a ocupação de microhabitat por espécies de peixes. Esta abordagem de simulação de hábitat foi adotada para avaliar os efeitos ecológicos sobre três espécies de peixes tropicais de diferentes ordens (Bryconamericus ornaticeps , Ancistrus multispinis e Geophagus brasiliensis ) em dois trechos de um riacho de Mata Atlântica do sudeste do Brasil, durante a estação chuvosa de 2013 e a estação seca de 2014. Características topográficas e hidráulicas (profundidade, velocidade e tipo de substrato) foram mensuradas para implementação da simulação de habitat em uma dimensão; observações subaquáticas dos peixes foram realizadas para avaliação do uso do microhabitat. As curvas de aptidão de habitat de cada variável hidráulica foram utilizadas na simulação de habitat para obtenção das curvas de aptidão composta (HSI) e a área útil ponderada (WUA) versus fluxo, e propor vazões ambientais mínimas e ideais para as espécies de peixes-alvo. A amplitude de vazão de 0,65-0,85 m3/s foi registrada como o ótimo para satisfazer as necessidades das três espécies de peixes. Esta é uma informação objetiva para os gestores de recursos hídricos e que pode ser aplicada no planejamento de programas de gestão visando a conservação dos ecossistemas. Desse modo, pode ser considerado um estudo piloto bem sucedido na avaliação do fluxo ambiental em um riacho da Mata Atlântica do Brasil.(AU)

Assuntos

RESUMO

The physical habitat simulation sub-routine of the Instream Flow Incremental Methodology (IFIM) uses hydraulic modeling and suitability indices of target fish species to predict how differences in-stream flows affect the microhabitat occupation by fish species. This habitat modelling approach was adopted to assess the ecological effects of running flows on three neotropical fish species of different orders (Bryconamericus ornaticeps , Ancistrus multispinis and Geophagus brasiliensis ).The study encompassed two reaches of an Atlantic Forest stream in Southeastern Brazil where topographic and hydraulic (depth, velocity and type of substrate) characteristics were measured to implement one-dimensional hydraulic simulation. Sub aquatic observation of fish was performed to collect data on microhabitat use and these data were used to develop habitat suitability curves that were used in the habitat simulation to obtain the habitat suitability index (HSI) and weighted usable area (WUA) versus flow curves. Upon these curves minimum and optimum environmental flows for the target fish species were proposed. Bryconamericus ornaticeps and A. multispinis selected microhabitats around 0.6 m depth, whereas G. brasiliensis showed a wider suitable range (0.35-0.9 m). All the three species were mainly observed in microhabitat with low flow velocity (0.1 m/s). Bryconamericus ornaticeps selected more frequently coarse substrate (e.g. boulders) but it appeared also over sandy substrate, whereas A. multispinis and G. brasiliensis selected preferably boulders. The range of 0.65-0.85 m3/s was found as the optimum to meet the needs of the three fish species. Our results agree with the necessary objective information to perform grounded management actions in the frame of a management program aiming at ecosystem conservation. Thereby it can be considered a successful pilot study in environmental flow assessment in an Atlantic Forest stream of Brazil.

A sub-rotina simulação de habitat físico da metodologia incremental - IFIM usa variáveis hidráulicas e os índices de aptidão das espécies alvo para predizer como diferentes vazões afetam a ocupação de microhabitat por espécies de peixes. Esta abordagem de simulação de hábitat foi adotada para avaliar os efeitos ecológicos sobre três espécies de peixes tropicais de diferentes ordens (Bryconamericus ornaticeps , Ancistrus multispinis e Geophagus brasiliensis ) em dois trechos de um riacho de Mata Atlântica do sudeste do Brasil, durante a estação chuvosa de 2013 e a estação seca de 2014. Características topográficas e hidráulicas (profundidade, velocidade e tipo de substrato) foram mensuradas para implementação da simulação de habitat em uma dimensão; observações subaquáticas dos peixes foram realizadas para avaliação do uso do microhabitat. As curvas de aptidão de habitat de cada variável hidráulica foram utilizadas na simulação de habitat para obtenção das curvas de aptidão composta (HSI) e a área útil ponderada (WUA) versus fluxo, e propor vazões ambientais mínimas e ideais para as espécies de peixes-alvo. A amplitude de vazão de 0,65-0,85 m3/s foi registrada como o ótimo para satisfazer as necessidades das três espécies de peixes. Esta é uma informação objetiva para os gestores de recursos hídricos e que pode ser aplicada no planejamento de programas de gestão visando a conservação dos ecossistemas. Desse modo, pode ser considerado um estudo piloto bem sucedido na avaliação do fluxo ambiental em um riacho da Mata Atlântica do Brasil.

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