Variation in species diversity of deep-water megafauna assemblages in the Caribbean across depth and ecoregions

Using deep-sea images to examine ecosystem services associated with methane seeps

Deep-sea images are routinely collected during at-sea expeditions and represent a repository of under-utilized knowledge. We leveraged dive videos collected by the remotely-operated vehicle Hercules (deployed from E/V Nautilus, operated by the Ocean Exploration Trust), and adapted biological trait analysis, to develop an approach that characterizes ecosystem services. Specifically, fisheries and climate-regulating services related to carbon are assessed for three southern California methane seeps: Point Dume (∼725 m), Palos Verdes (∼506 m), and Del Mar (∼1023 m). Our results enable qualitative intra-site comparisons that suggest seep activity influences ecosystem services differentially among sites, and site-to-site comparisons that suggest the Del Mar site provides the highest relative contributions to fisheries and carbon services. This study represents a first step towards ecosystem services characterization and quantification using deep-sea images. The results presented herein are foundational, and continued development should help guide research and management priorities by identifying potential sources of ecosystem services.

Testing marine regional-scale hypotheses along the Yucatan continental shelf using soft-bottom macrofauna

Different hypotheses related to the regional-scale configuration of the Yucatan Continental Shelf (YCS) between the Gulf of Mexico (GoM) and the Caribbean Sea have been proposed. Hypotheses regarding its regional boundaries include: (i) an ecoregional boundary at Catoche Cape, dividing the Western Caribbean and the Southern GoM ecoregions; and (ii) a boundary within the Southern GoM ecoregion at 89°W, separating the West and Mid-Yucatan areas. We tested the hypothesis of no variation in benthic macrofaunal assemblages between regions delimited by the former boundaries using the species and functional traits of soft-bottom macrofauna. We considered that the depth and temporal environmental dynamics might interact with regional variations, generating complex benthic community patterns. The data were collected over five years (2010–2012, 2015–2016) at 86 stations (N = 1, 017 samples, 10–270 m depth), comprising 1,327 species with 45 combinations of functional traits. The variation in species composition and functional trait assemblages were both consistent with the occurrence of three separate regions in the Yucatan Peninsula (West Yucatan, Mid-Yucatan and Western Caribbean). This regional configuration was consistent with changes in assemblage structure and depth zonation as well as temporal variation. Along with spatial and temporal variation, diversity diminished with depth and different regions exhibited contrasting patterns in this regard. Our results suggest that the spatial and temporal variation of soft-bottom macrofauna at YCS demonstrate the complex organization of a carbonate shelf encompassing different regions, which may represent transitional regions between the Caribbean and the GoM.

Assemblages of certain benthic molluscs along the southwestern Atlantic: from subtidal to deep sea

Background

We analyse the distribution of Gastropods and Chitons from shallow to deep waters along the southwestern Atlantic Ocean off Argentina and discuss possible factors determining the observed biogeographic patterns.

Results

Three major biogeographic groups are defined on the basis of Gastropod and Chiton species associations, i.e., continental shelf (< 350 m), upper continental slope (> 350–2000 m) and lower continental slope (2000–3000 m). Bathymetry appears as the main factor modifying large-scale distribution of the fauna at a. In this scenario, species associations are determined by marine currents that clearly occur at a particular and well defined depth. No arrangement of species by geographic location was found in assemblages from the continental shelf and upper continental slope.

Conclusions

We hypothesize that depth and marine currents are the main factor affecting the distribution of Gastropods and Chitons along the SW Atlantic between 200 and 3000 m depth.

Updated taxonomic list and conservation status of chondrichthyans from the exclusive economic zone of Venezuela, with first generic and specific records

Using the last taxonomic review of chondrichthyans of the world, we selected the species distributed in the north-western Atlantic Ocean (NWA) and compared it with the available published literature related to the class Chondrichthyes in the Venezuelan exclusive economic zone. We also revised information from worldwide databases such as: FAO (NWA-31 area), GBIF, iSpecies, IUCN and OBIS, as well as available museum collection databases. The taxonomic validity was checked using the Catalogue of Fishes of the California Academy of Sciences and recent references. The past published Venezuelan lists of chondrichthyans combined included nine orders, 30 families and 108 species. The updated list with 12 orders, 36 families and 122 species increased by three new orders, six families, three shark genera, nine shark species (one replacing another species), one chimaera genus, two chimaera species, three batoid genera and six batoid species (two replacing other species). Four holotype specimens (two sharks and two rays) are deposited in Venezuelan Museums. Most of the species have an IUCN conservation status, including four species catalogued as Critically Endangered, six as Endangered and 18 species as Vulnerable. Deep-sea fisheries, scientific exploration and taxonomic/genetic revisions might add future increments to the Venezuelan chondrichthyan list.

Natural history collections as a basis for sound biodiversity assessments: Plexauridae (Octocorallia, Holaxonia) of the Naturalis CANCAP and Tyro Mauritania II expeditions

Mapping biodiversity is the marathon of the 21^st Century as an answer to the present extinction crisis. A century in which science is also characterised by large scientific datasets collected through new technologies aiming to fill gaps in our knowledge of species distributions. However, most species records rely on observations that are not linked to specimens, which does not allow verification of species hypotheses by other scientists. Natural history museums form a verifiable source of biodiversity records which were made by taxonomists. Nonetheless, these museums seem to be forgotten by biologists in scientific fields other than taxonomy or systematics. Naturalis Biodiversity Center (NBC) in Leiden is care keeper of large collections of marine organisms, which were sampled in the Northeast Atlantic during the CANCAP and Tyro Mauritania II expeditions (1976–1988). Many octocorals were sampled and deposited in the NBC collection, where they became available for study and were partially identified by the senior author (M.G.) in the 1980s. Nonetheless, no checklist or taxonomic revision was published so far with the complete results. In 2016 the first author visited NBC to examine NE Atlantic Plexauridae octocorals. Plexauridae octocoral-vouchered records were listed and mapped to reveal high standard primary biodiversity records unreported so far for the NE Atlantic Ocean. Twenty-four Plexauridae species with ~ six putative new species to science were discovered and eleven new biogeographical records were made from distinct Macaronesian archipelagos. Finally, new depth range records were found for three species at sea basin level and for eight species at a regional scale.