Marine mammals are believed to exert a strong influence on ecosystems, though the best methods fo... more Marine mammals are believed to exert a strong influence on ecosystems, though the best methods for measuring their ecological role have long been debated. Here, we used an ecosystem modelling approach to explore the underlying forces that define their ecological role, with a focus on predatory effects. We used the outputs and metadata from 55 food web models built using Ecopath with Ecosim software to analyse the effects of several likely explanatory variables on 2 indices of trophic significance: the relative trophic impact (TI) and the ‘keystoneness’ index (KS). Results showed that both TI and KS are positively related to trophic level. We also found an additional effect of group biomass in both TI and KS, but this response was clade-dependent: the higher the biomass, the higher the TI and KS of odontocetes and pinnipeds, suggesting that food intake contributes to the predatory effects of these clades through biomass variation. We did not detect a latitudinal pattern in the ecolog...
Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surroun... more Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surrounded by a network of Marine Protected Areas. The objectives of this study were to describe the composition of the demersal fish assemblage, identify seasonal and spatial structures on a fine scale and evaluate the role of habitat descriptors and abiotic variables affecting the fish assemblage structure. Seasonal samplings were conducted in 2005, using bottom trawls in six pre-established areas in Baía Norte in summer, fall, winter and spring. Simultaneously with each trawl, environmental data were collected with a multiparameter probe. Temporal and spatial differences in fish abundance were tested by a PERMANOVA. To illustratethe differences detected graphically we ran a canonical analysis of principal coordinates (CAP). The influence of environmental variables on the fish fauna was evaluated using a Distant Based Linear Model (DistLM) with Akaike's information criterion (AIC). A tota...
A toninha (Pontoporia blainvillei) é considerada a espécie de golfinho mais ameaçada da costa do ... more A toninha (Pontoporia blainvillei) é considerada a espécie de golfinho mais ameaçada da costa do Brasil. As populações de toninha que ocorrem no litoral norte do estado do Espírito Santo constituem populações isoladas, separadas por um hiato geográfico das demais populações. Da mesma forma, não há informações sobre hábitos alimentares de golfinhos franciscanos na área de estudo. O objetivo desta pesquisa é descrever a dieta da toninha na costa norte do Espírito Santo. Foram analisados 18 conteúdos estomacais de carcaças encalhadas no período de janeiro/2012 a março/2015. Foram contabilizados os itens da dieta identificados e calculadas a frequência de ocorrência e a abundância relativa das presas. São apresentados novos registros de presas para a espécie. A presa mais comum encontrada na dieta da toninha foi Isopisthus parvipinnins. Assim como em outras localidades, a família Sciaenidae foi o grupo mais importante na dieta de Pontoporia blainvillei no Espírito Santo, seguida por pre...
Marine mammals are believed to exert a strong influence on ecosystems, though the best methods fo... more Marine mammals are believed to exert a strong influence on ecosystems, though the best methods for measuring their ecological role have long been debated. Here, we used an ecosystem modelling approach to explore the underlying forces that define their ecological role, with a focus on predatory effects. We used the outputs and metadata from 55 food web models built using Ecopath with Ecosim software to analyse the effects of several likely explanatory variables on 2 indices of trophic significance: the relative trophic impact (TI) and the ‘keystoneness’ index (KS). Results showed that both TI and KS are positively related to trophic level. We also found an additional effect of group biomass in both TI and KS, but this response was clade-dependent: the higher the biomass, the higher the TI and KS of odontocetes and pinnipeds, suggesting that food intake contributes to the predatory effects of these clades through biomass variation. We did not detect a latitudinal pattern in the ecolog...
Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surroun... more Baía Norte (North Bay) in Santa Catarina State is considered a typical coastal bay and is surrounded by a network of Marine Protected Areas. The objectives of this study were to describe the composition of the demersal fish assemblage, identify seasonal and spatial structures on a fine scale and evaluate the role of habitat descriptors and abiotic variables affecting the fish assemblage structure. Seasonal samplings were conducted in 2005, using bottom trawls in six pre-established areas in Baía Norte in summer, fall, winter and spring. Simultaneously with each trawl, environmental data were collected with a multiparameter probe. Temporal and spatial differences in fish abundance were tested by a PERMANOVA. To illustratethe differences detected graphically we ran a canonical analysis of principal coordinates (CAP). The influence of environmental variables on the fish fauna was evaluated using a Distant Based Linear Model (DistLM) with Akaike's information criterion (AIC). A tota...
A toninha (Pontoporia blainvillei) é considerada a espécie de golfinho mais ameaçada da costa do ... more A toninha (Pontoporia blainvillei) é considerada a espécie de golfinho mais ameaçada da costa do Brasil. As populações de toninha que ocorrem no litoral norte do estado do Espírito Santo constituem populações isoladas, separadas por um hiato geográfico das demais populações. Da mesma forma, não há informações sobre hábitos alimentares de golfinhos franciscanos na área de estudo. O objetivo desta pesquisa é descrever a dieta da toninha na costa norte do Espírito Santo. Foram analisados 18 conteúdos estomacais de carcaças encalhadas no período de janeiro/2012 a março/2015. Foram contabilizados os itens da dieta identificados e calculadas a frequência de ocorrência e a abundância relativa das presas. São apresentados novos registros de presas para a espécie. A presa mais comum encontrada na dieta da toninha foi Isopisthus parvipinnins. Assim como em outras localidades, a família Sciaenidae foi o grupo mais importante na dieta de Pontoporia blainvillei no Espírito Santo, seguida por pre...
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