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Climate change is triggering shifts in species distribution eventually altering communities' biogeography. The composition of a community in terms of its species' ecological niche informs of a community's response to environmental conditions and impacts, which is central for a timely conservation. While the thermal niche has been widely explored, given it offers a direct link of warming effects on an assemblage, acknowledging the multivariate nature of a species niche can provide relevant insights of the reorganizations taking place at a community-level. We studied the mean and variance of 10 ecological traits at the community level in two regional ecosystems in the temperate East-Atlantic and the Mediterranean Sea, characterized by a distinct exposure to warming. Our findings revealed major temporal changes and spatial structuring in the traits and ranges explored over the last decades. Apart from confirming the expected general poleward, deep-ward shift, our results highlighted a widening of thermal and latitudinal ranges, possibly related to a ‘flexibilitation’ of the communities in a context of global change. In addition, temporal patterns reflected how communities have adjusted around regime shifts known in both areas. Regional differences arose concerning the variance of depth ranges and area of distribution, as well as to the global evolution of the communities, which we argue are consequence of their different geographical features and ecological history. The comparison of two large multitaxon assemblages has disclosed a broad-scale motion of response to warming in the bentho-demersal domain. We expect this study will contribute to the understanding of the multivariate nature of global-change effects on marine fauna, which ultimately informs adaptive management.

Pyrosomes are an important but often overlooked component of marine zooplankton communities, with limited existing information regarding their ecological and trophic roles in pelagic ecosystems. We present the first estimates of grazing and trophic interactions of the large tropical pyrosome, Pyrostremma spinosum, in the Eastern Tropical Pacific. While patchy in distribution, Pyrostremma spinosum'sgrazing impact was substantial, up to 17.5% of chlorophyll astanding stock d−1in certain areas. In contrast, these organisms cleared a very small percentage of the abundant picoplankton Synechococcusspp. compared to the bulk zooplankton community. Stable isotopes (13C and 15N) indicated that particulate organic matter (POM) from the surface mixed layer (0–20 m) constitutes the isotopic food‐web baseline for most of the zooplankton community, and zooplankton trophic interactions were size structured in some areas. Pyrosomes, doliolids, and appendicularians, along with the smallest size class of net‐collected zooplankton, had isotopic values closest to pure herbivory, while intermediate size classes, copepods, and salps showed substantial omnivory/carnivory. Euphausiids, chaetognaths, and > 2 mm zooplankton were the main carnivorous zooplankton in the plankton food web. Stable isotopes indicated that Pyrostremma spinosumis trophically distinct from the rest of the zooplankton community, grazing just below the mixed layer (20–40 m), as opposed to feeding on surface POM. Pyrosomes represent an additional, distinct pathway for material transfer up the plankton food web, by directly consuming POM sources not substantially grazed upon by the rest of the mesozooplankton community.

We examined the ingestion of meso- and macro-plastics by teleost fish and elasmobrachs with benthic- demersal dwelling habits, analysing the occurrence of this litter type on the diet of 39 of these species over the North-western Iberian Shelf Sea between 1999 and 2016. Plastic consumption seems to be incidental, occurring only in 7 of the 39 species examined, and in a very low proportion (<0.3% of individuals in all cases). The highest rates were found among benthic feeding elasmobranchs, including Leucoraja naevus, Scyliorhinus caniculaand Galeus spp., the two latter being opportunistic scavengers. While our study rules out a high occurrence of meso- and macro- plastics in benthic fauna, the presence of micro-plastics in the diet of these species is still a major concern, as the deep sea is possibly a natural sink for these litter particles.