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- Trophic interactions of two sympatric small pelagic fishes off the southern coast of AngolaPublication . Quiatuhanga, Domingas; Morais, Pedro; Teodosio, MariaNumerous small pelagic fish species are of great economic importance and link the lower and upper levels of the marine food web. The round sardinella Sardinella aurita and flat sardinella S. maderensis coexist along their distribution range in the southeastern Atlantic Ocean, where we hypothesise that they compete for similar prey. Thus, this study aimed to compare the trophic ecology of these species off the southern coast of Angola during the austral summer and winter, by determining their diet composition and overlap, feeding strategies, trophic positions, and evaluating the correlation between their feeding intensity and remote-derived chlorophyll a concentration (Chl-a) and sea surface temperature. The results demonstarte that both species are generalists and ingest a wide range of protistoplankton and metazooplankton taxa of distinct sizes. Both sardinellas show high flexibility and adaptability to prey availability, using both filter-feeding and particulate-feeding modes. The diets were dominated by diatoms and calanoid copepods in terms of relative abundances and frequencies of occurrence, respectively, in the stomach contents. Tintinnid ciliates, fish eggs, decapod larvae, euphausiids, cladocerans and cnidarians had high wet weight contributions. The diets overlapped by 64% overall, indicating moderate competition for food, with S. maderensis exhibiting a lower trophic position than S. aurita (2.98 versus 3.49). The feeding intensity of S. maderensis was positively correlated with Chl-a, and moderately negatively correlated with SST, suggesting that species is more influenced by environmental variables owing to its lower trophic position. Trophic interactions between the two species appear to be mediated by prey sizes and availability. These findings demonstate the value of satellite-derived data as proxies to estimate the feeding intensity of these species, which will be useful to formulate regional ecological models or to predict the stock trends of S. maderensis in particular.
- “Pink power”—the importance of coralline algal beds in the oceanic carbon cyclePublication . Schubert, Nadine; Tuya, Fernando; Peña, Viviana; Horta, Paulo A.; Salazar, Vinícius W.; Neves, Pedro; Ribeiro, Cláudia; Otero-Ferrer, Francisco; Espino, Fernando; Schoenrock, Kathryn; Ragazzola, Federica; Olivé, Irene; Giaccone, Thalassia; Nannini, Matteo; Mangano, M. Cristina; Sará, Gianluca; Mancuso, Francesco Paolo; Tantillo, Mario Francesco; Bosch-Belmar, Mar; Martin, Sophie; Gall, Line Le; Santos, Rui; Silva, joãoCurrent evidence suggests that macroalgal-dominated habitats are important contributors to the oceanic carbon cycle, though the role of those formed by calcifiers remains controversial. Globally distributed coralline algal beds, built by pink coloured rhodoliths and maerl, cover extensive coastal shelf areas of the planet, but scarce information on their productivity, net carbon flux dynamics and carbonate deposits hampers assessing their contribution to the overall oceanic carbon cycle. Here, our data, covering large bathymetrical (2–51 m) and geographical ranges (53°N–27°S), show that coralline algal beds are highly productive habitats that can express substantial carbon uptake rates (28–1347 g C m−2 ), which vary in function of light availability and species composition and exceed reported estimates for other major macroalgal habitats. This high productivity, together with their substantial carbonate deposits (0.4–38 kilotons), renders coralline algal beds as highly relevant contributors to the present and future oceanic carbon cycle.