The importance of coastal morphology, and its influence on the magnitude of larval delivery and subsequent recruitment patterns of brachyuran decapods, was investigated at a broad range of spatial and temporal scales along the central coast of Chile. Larvae were quantified through plankton net towing as well as by using artificial settlement collectors deployed at different depths, while the abundance of benthic stages was quantified via in situ SCUBA airlifting and visual surveys. The abundance of young-of-the-year (YOY) and of individuals older than 1 yr (>1 yr) was compared between sites with contrasting conditions of coastal exposure at peninsulas several hundred kilometers apart. Additionally, we pursued a temporally more detailed surveying program, which included more species, at the southernmost peninsula. From our results we conclude that: (1) in general, the abundance of Paraxanthus barbiger, the most abundant species throughout, was greater at all locations in 2003 compared with 2004 and it was also greater (particularly >1 yr individuals) at protected sites; (2) for most of the species, the abundance of megalopae and YOY was highly seasonal, with peaks during the austral spring and summer months; and (3) for at least 2 of the 4 species considered in the southernmost peninsula, the abundance of YOY and >1 yr individuals exhibited higher abundance at the protected site. In spite of our efforts, we failed to find significant correlation between local abundance of settlers on artificial collectors and YOY individuals that settled in nursery habitats directly below. Post-settlement mortality, operating very soon after settlement, is a likely explanation for this finding. Our study highlights the importance of considering factors such as coastal morphology together with the occurrence of post-settlement processes when studying coastal organisms with complex life cycles.
The emergence of open ocean global-scale studies provided important information about the genomics of oceanic microbial communities. Metagenomic analyses shed light on the structure of marine habitats, unraveling the biodiversity of different water masses. Many biological and environmental factors can contribute to marine organism composition, such as depth. However, much remains unknown about microbial communities’ taxonomic and functional features in different water layer depths. Here, we performed a metagenomic analysis of 76 publicly available samples from the Tara Ocean Project, distributed in 8 collection stations located in tropical or subtropical regions, and sampled from three layers of depth (surface water layer—SRF, deep chlorophyll maximum layer—DCM, and mesopelagic zone—MES). The SRF and DCM depth layers are similar in abundance and diversity, while the MES layer presents greater diversity than the other layers. Diversity clustering analysis shows differences regarding the taxonomic content of samples. At the domain level, bacteria prevail in most samples, and the MES layer presents the highest proportion of archaea among all samples. Taken together, our results indicate that the depth layer influences microbial sample composition and diversity.
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