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This paper compiles the data regarding the first occurrence of Oithona davisae and O. atlantica in NW Spain, which is supported by morphological and molecular analysis. Additionally, we investigated the seasonal dynamics of the invasive O. davisae, revealing that its abundance is conditioned by upwelling-downwelling patterns in the Rías Baixas of Galicia. Temperature was the most correlated factor, with higher abundances in upwelling relaxation-downwelling events. More studies in long-term zooplankton dynamics and molecular analysis are needed to determine if O. davisae is displacing other native species of the same genus, such as O. atlantica, in Galician waters. [ABSTRACT FROM AUTHOR]

Global ecosystem models are essential tools for predicting climate change impacts on marine systems. Modeled biogenic carbon fluxes in the ocean often match measured data poorly and part of this could be because small copepods (<2 mm) are modeled as unicellular feeders grazing on phytoplankton and microzooplankton. The most abundant copepods from a seasonal upwelling region of the Eastern North Atlantic were sorted, and a molecular method was applied to copepod gut contents to evaluate the extent of metazoan predation under two oceanographic conditions, a trophic pathway not accounted for in global models. Scaling up the results obtained herein, based on published field and laboratory estimates, suggests that small copepods could ingest 1.79–27.20 gigatons C/year globally. This ignored metazoan‐copepod link could increase current estimates of biogeochemical fluxes (remineralization, respiration, and the biological pump) and export to higher trophic levels by 15.6%–24.4%. It could also account for global discrepancies between measured daily ingestion and copepod metabolic demand/growth. The inclusion of metazoan predation into global models could provide a more realistic role of the copepods in the ocean and if these preliminary data hold true at larger sample sizes and scales, the implications would be substantial at the global scale. Global ecosystem models (GEMs) are essential tools to make predictions about biogeochemical budgets, fisheries yields or the fate of anthropogenic carbon, but these models have a substantial mismatch between measured and modeled carbon. Copepods are the most abundant multicellular animals on Earth but GEMs currently have copepods feeding only on single cell protists, despite the fact that they also prey upon metazoans, potentially reducing the amount of carbon entering the pelagic food webs. Using a meta‐analysis on published copepod feeding rates, the metazoan‐copepod link was estimated to be between 1.79 and 27.20 gigatons of C/year at a global scale using field and laboratory estimations, which could increase current estimates of biogeochemical fluxes by 15.6%–24.4%. [ABSTRACT FROM AUTHOR]

Under the influence of the Western Iberian upwelling system, the Iberian Atlantic coast holds important hatcheries and recruitment areas for Octopus vulgaris. Recently identified as an octopus hatchery, the Ría de Vigo harbors an important mesozooplankton community that supports O. vulgaris paralarvae during the first days of their planktonic stage. This study represents a preliminary approach to determine the nutritional link between wild O. vulgaris hatchlings, paralarvae and their zooplankton prey in the Ría de Vigo, by analyzing their lipid class content and fatty acid profiles. The results show that octopus hatchlings are richer in structural lipids as phospholipids and cholesterol, while the zooplankton is richer in reserve lipids like triacylglycerol and waxes. Zooplankton samples are also particularly rich in C18:1n9 and 22:6n3 (DHA), that seem to be successfully incorporated by O. vulgaris paralarvae thus resulting in a distinct fatty acid profile to that of the hatchlings. On the other hand, content in C20:4n6 (ARA) is maintained high through development, even though the zooplankton is apparently poorer in this essential fatty acid, confirming its importance for the development of O. vulgaris paralarvae. The content in monounsaturated fatty acids, particularly C18:1n7, and the DHA: EPA ratio are suggested as trophic markers of the diet of O. vulgaris paralarvae. [ABSTRACT FROM AUTHOR]

The euphausiidNyctiphanes couchiiand an unidentified mysid have been found, for the first time, with third-stage larvae (L3) of theAnisakis simplexcomplex in the mesozooplanktonic community of the coastal upwelling system in Galicia (NW Spain). Parasite larvae were molecularly identified using the internal transcribed spacer (ITS) region. The prevalence of these parasites in the euphausiid population was 0.0019%. The existence of parasites in a variety of mesozooplankton organisms suggests that the transmission routes ofA. simplexsensu stricto andA. pegrefiiare wider than expected. The results suggest that these twoAnisakisspecies are not specific to their intermediate hosts. Finally, the recruitment ofA. simplexcomplex may be affected by oceanography, differing under upwelling or downwelling conditions. [ABSTRACT FROM PUBLISHER]

Abstract: The short-term, meso-scale variability of the mesozooplankton community present in the coastal upwelling system of the Ría de Vigo (NW Spain) has been analysed. Three well-defined communities were identified: coastal, frontal and oceanic, according to their holoplankton–meroplankton ratio, richness, and total abundance. These communities changed from summer to autumn due to a shift from downwelling to upwelling-favourable conditions coupled with taxa dependent changes in life strategies. Relationships between the resemblance matrix of mesozooplankton and the resemblance matrices of meteorologic, hydrographic and community-derived biotic variables were determined with distance-based linear models (DistLM, 18 variables), showing an increasing amount of explained variability of 6%, 16.1% and 54.5%, respectively. A simplified model revealed that the variability found in the resemblance matrix of mesozooplankton was mainly described by the holoplankton–meroplankton ratio, the total abundance, the influence of lunar cycles, the upwelling index and the richness; altogether accounting for 64% of the total variability. The largest variability of the mesozooplankton resemblance matrix (39.6%) is accounted by the holoplankton–meroplankton ratio, a simple index that describes appropriately the coastal–ocean gradient. The communities described herein kept their integrity in the studied upwelling and downwelling episodes in spite of the highly advective environment off the Ría de Vigo, presumably due to behavioural changes in the vertical position of the zooplankton. [Copyright &y& Elsevier]