Drivers of niche partitioning in a community of mid-trophic level epipelagic species in the North Atlantic

Abstract

According to the principles of community ecology, sympatric species may suffer a selective pressure to decrease their niche overlap through mechanisms of niche partitioning. However, there is still a gap in knowledge of the main drivers influencing niche differentiation, particularly in communities composed by small-sized and inconspicuous species. The coastal epipelagic community structure of mid-trophic level species in the Northeast Atlantic was examined using stable isotope analysis to (1) decipher intrinsic and extrinsic factors promoting niche partitioning and (2) examine species divergence in the use of resources. A total of 474 individuals from a guild of 11 species were sampled during three years, and the influence of potential drivers of isotopic divergence was assessed. The niche partitioning was mainly determined by the taxonomic group in accordance with the fundamental principles of niche theory, which was consistent for both δ13C (i.e. habitat) and δ15N (i.e. prey). Body size was highly important in driving niche partitioning within species. Our results show that the predominant species in the guild were the most generalist, when compared with more specialised species with which they coexist. This study reveals that the intrinsic factors are determinant to decrease inter- and intra-specific niche overlap at the community level.

Gulls as Indicators of Environmental Changes in the North Atlantic: A Long-Term Study on Berlenga Island, Western Portugal

“…In addition, several relationships were detected between SIA variables with both SST and Chl-a, including models involving SEAc values, highlighting the influence of oceanographic dynamics on the trophic ecology of gulls. Such isotopic composition differences are commonly linked to environmental drivers, such as SST and Chl-a concentration in species spanning from mid-to higher trophic levels within the study area [70,71]. These findings underline the significant influence of oceanographic conditions on the trophic ecology of gulls.…”

“…In our study both δ 13 C and δ 15 N values showed a large variation over the years, in both RBC (representing the pre-laying) and plasma (reflecting incubation). We identified significant relationships between δ 15 N values and fisheries landings, particularly in the case of demersal carnivorous species (e.g., Diplodus spp., Merluccius merluccius), which are more likely to exhibit higher δ 15 N values [29,70]. These species are unlikely to be captured by gulls under natural conditions, further supporting the idea of a fisheries subsidy, particularly through discards, to their diet [37].…”

“…Therefore, substantial temporal variations in oceanographic conditions determining the abundance of marine resources might occur, such as those indicated by the Chl-a concentration, which correlates positively with the density of low-trophic level marine species like the Henslow's swimming crab [69]. These fluctuations can significantly impact the trophic ecology of both mid-trophic level species [70] and top predators like seabirds [71]. However, direct observed effects on breeding performance may be more challenging to discern.…”

Long‐term evolution of the structure of the St. Lawrence (Canada) marine ecosystem in the context of climate change and anthropogenic activities: An isotopic perceptive

“…This study indicates a stronger ecological niche partitioning in recent years, as revealed by the relatively small (<30%) overlap of SEA B among species (Ceia et al., 2023 ; Golikov et al., 2020 ; Langton, 1982 ). All species where a decrease in niche size was observed over time adhered to this pattern, where the decrease in niche breadth was concomitant to a decrease in overlap with potential competitors (Tables 1 and 2 ).…”

“…This study indicates a stronger ecological niche partitioning in recent years, as revealed by the relatively small (<30%) overlap of SEA B among species (Ceia et al, 2023;Golikov et al, 2020;Langton, 1982).…”