Microbial communities fundamentally shape ecosystem function and biodiversity across all biological systems through complex dynamics. In coral reef ecosystems, understanding the dynamics of these microbial communities has become critical for predicting reef responses to environmental stressors. Fish skin microbiota are highly susceptible to environmental changes and may vary significantly across species and geographic locations, yet the extent to which these variations occur remain poorly understood. Here, we compared the skin microbiota of four closely related and sympatric cryptobenthic gobiid species, that exhibit different behavioral ecologies (cleaning vs.non-cleaning), ecological niches (water column, coral-, or sand-dwelling) and phylogenetic affinities (Elacatinus vs. Coryphopterus), yet reside in the same reef patches in St. Croix and Puerto Rico, eastern Caribbean. Coral-dwelling gobies, including cleaning sharknose and non-cleaning peppermint gobies, exhibited significantly lower microbial diversity compared to reef-hovering and sand-dwelling species (both non-cleaning). These coral dwellers showed unique microbial signatures despite having similar alpha diversity levels. Core microbiota analysis also revealed striking differences between coral-dwelling and reef-hovering/sand-dwelling species, with the core microbiome of the former dominated by Vibrio, Pseudoalteromonas, and Alteromonas in the case of cleaning gobies and by Endozoicomonas in the case of peppermint gobies, while reef-hovering and sand-dwelling gobies exhibited diverse core microbiota with greater overlap between species. Ecological niche occupancy and reef habitat selection appear to be primary drivers of skin microbiota composition in gobiid fishes, rather than cleaning behavior and/or host phylogenetic affinities alone, though species-specific skin mucus properties likely also contribute to selective bacterial colonization patterns.
The atmospheric response to the solar eclipse of 8 April 2024 in North America is investigated with a specific focus on the marine atmospheric boundary layer (MABL). We leverage measurements collected during the Third Wind Forecast Improvement Project (WFIP3), including Doppler lidars, sonic anemometers, and thermodynamic profiler data to investigate the atmospheric response across sites that experienced partial eclipse conditions with nearly 90 1.2^∘C to 1.4^∘C in coastal regions and from 0.3^∘C to 0.5^∘C over the ocean. This analysis suggests that the MABL’s higher thermal inertia compared to coastal regions moderates the temperature decrease during the eclipse. Wind speed exhibits a more complex behavior, as it is influenced by both the MABL and preexisting synoptic conditions. Although a reduction in wind speed is observable up to approximately 140 m above ground level (AGL) at more inland sites, at other locations closer to the coast, this reduction is constrained to the lowest 100 m AGL. Turbulence parameters retrieved from sonic anemometers, such as turbulence kinetic energy, turbulent heat flux, and friction velocity, decrease during the eclipse at coastal sites, accompanied by a brief transition of atmospheric stability from unstable to neutral or weakly stable conditions. For the open-ocean sites, the variability in turbulence statistics and atmospheric stability is minimal during the occurrence of the eclipse.
The Western Indian Ocean (WIO) is known for its high diversity of chondrichthyans (sharks, rays, and chimaeras). However, intense fishing pressure has led to severe population declines and local extinctions of several species. The Important Shark and Ray Area (ISRA) process is a collaborative, evidence-based approach used to identify critical habitat for chondrichthyans. We analysed ISRAs across the WIO to quantify the diversity of research methods used to identify them, evaluate spatial overlap with designated marine protected areas (MPAs), model the influence of several species- and jurisdiction-specific variables on ISRA delineation, and explore the importance of incorporating unpublished data into the delineation process. In total, 125 ISRAs (covering > 2.8 million km2; ~10% of total regional surface area) were identified within the WIO from surface waters to ~2000 m depth. These ISRAs contain over one-third (n = 104, 39%) of the 270 chondrichthyan species reported from the region, with 76% being threatened with extinction according to the IUCN Red List of Threatened Species. The underlying evidence supporting ISRA identification was primarily drawn from relatively inexpensive research methods, such as visual census (25%) or fish-market/landing site surveys (22.6%), as well as citizen science (9.5%). Incorporating unpublished records substantially increased the frequency of ISRA delineation, leading to expanded taxonomic and geographic coverage. Still, the full dataset was influenced by the same biases as the published record, tending to favour large-bodied, wide-ranging, and shallow-dwelling species. Only 7.1% of ISRAs are within designated MPAs, with just 1.2% in fully protected no-take areas. The highest no-take overlap occurs in the Seychelles and Chagos Archipelago. These findings highlight the shortfalls in spatial protection of chondrichthyan habitats, but also present a strategic opportunity for policy-makers and resource managers to improve current MPA coverage and meet their commitments under international agreements, such as the Global Biodiversity Framework.
Many of the outer Solar System’s icy satellites feature known or suspected subsurface oceans, at least some of which are likely situated atop rocky interiors. Water–rock interactions at and beneath these seafloors might support active chemoautotrophic habitats, with subseafloor fluid flow facilitated by active faulting and hydrothermal systems. Absent such phenomena, however, any attainment of chemical equilibrium between the seafloor and ocean might limit the availability of chemical energy for life. Here, we characterise the stress state of the seafloor of Jupiter’s moon Europa, and thus the prospect for fracturing and associated sub-seafloor fluid flow there. We consider stresses from tidal forcing, global contraction, mantle convection, and serpentinisation. We find that none of these mechanisms is likely able to drive slip along even weak, pre-existing fractures in the present. Ocean water–rock reactions taking place today are therefore probably restricted to fluid flow through only the upper few hundred metres of the seafloor. Any processes able to sustain habitable conditions at the Europan seafloor today must therefore be independent of ongoing tectonic activity. In this study, the authors model the current mechanical properties of the seafloor of Jupiter’s icy moon Europa, and find those rocks to be too strong to allow the kind of fracturing that, on Earth, enables rock–water chemical reactions on which chemosynthetic life relies.
Coral reefs are under threat worldwide. Yet, in these often-challenging marine habitats, biologists lack the tools to quantify the spatial heterogeneity of mobile reef fauna at high resolution (<1 meter), hampering monitoring and restoration efforts. Because of the diverse species present, multiple sensor modalities are needed to characterize the biodiversity. The urgent need to expand this study across unexplored reefs worldwide compounds these challenges. To address these problems, we propose a generative model of reef observations and develop a multimodal framework for seeking and mapping hotspots of biodiversity. In a case study on a healthy Caribbean reef, our autonomous underwater vehicle used passive acoustics and visual sensing to locate a biological hotspot around a large Dendrogyra pillar coral. We used the colocated multimodal data to self-validate the hotspot's prominence, representing a technological step forward to help understand the ecological dynamics of coral reefs.
