Biology subjects

Guibert, I.

Publications and source records attributed to Guibert, I..

4 recordsLinked to original sources

bioRxiv2026

Energy quality shapes biodiversity across coastal oceans

Earth's biodiversity is distributed unevenly, typically peaking in warm, vegetated, and stable environments. This has frequently been linked to energy availability, which boosts productivity, bolsters populations, and facilitates coexistence. Here, we examine the relationship between energy and biodiversity across coastal oceans using particulate organic matter biogeochemistry and environmental DNA. We reveal that energy quantity (concentrations of carbon, nitrogen, and hydrolyzable amino acids) and salinity, two variables that co-vary with freshwater inflow, jointly predict species richness at regional and global scales. Biodiversity was lowest at sites and locations with high energy inflow and low salinity, suggesting that environmental filtering associated with the osmotic stress induced by freshwater inflow outweighs raw resource availability in governing species richness. Independent of this gradient, however, energy quality (defined via C:N ratios, {delta}C values, and amino acid profiles) was associated with higher biodiversity. Labile, protein-rich, marine-derived resources supported higher biodiversity across all taxa at the regional scale, and a larger number of planktonic consumer taxa at both regional and global scales. High energy quality sites were also enriched in key planktonic groups such as calanoid and cyclopoid copepods, suggesting that these sites act as hotspots of planktonic biodiversity across coastal seascapes. Our findings suggest that few species can directly harness the plentiful resources provided by terrestrial subsidies in coastal oceans because they arrive in low salinity waters. In turn, high-quality food attracts a diverse range of consumers, which may seed the patchy foraging hotspots that characterize open-water food webs. Altered coastal hydrodynamics and biogeochemistry may therefore affect nearshore biodiversity, food webs, and fisheries.

ecology↗

bioRxiv2026

Pollution and Anthropogenic Stressors Are Associate with Cetacean Vulnerability in Coastal Waters: Fine-Scale Diagnostics from eDNA and Multispecies Modeling

Indo-Pacific humpback dolphin (Sousa chinensis) and finless porpoise (Neophocaena phocaenoides) are increasingly threatened across their native range, yet the relative influence of multiple stressors in shaping their population dynamics remains unclear. Current conservation strategies for both species are limited by incomplete data and limited assessment of affecting factors. Here, we integrated eDNA metabarcoding with Joint Species Distribution Modeling (JSDM) to assess how environmental gradients, pollution, and trophic associations interactively influence cetacean distributions in Hong Kong waters. We show that degraded water quality and intensified human activity negatively associated with cetacean occurrence, with clear species-specific responses to different stressors. S. chinensis covaried most strongly with Secchi disc depth, and presence of vessels, while N. phocaenoides was negatively associated with nitrate nitrogen and microbial pollution (sewage). The JSDM variance partitioning analysis highlighted that the occurrence of S. chinensis was primarily associated with anthropogenic disturbances (30.04%), followed by water physical properties (26.63%), whereas N. phocaenoides was more strongly associated with physical (40.9%) and anthropogenic disturbances (35.2%). By integrating eDNA and JSDM, our approach provides fine-scale diagnostics of species-specific vulnerabilities, supporting adaptive conservation strategies and guiding the realignment of protected areas to mitigate biodiversity loss in urbanized marine ecosystems. Environmental ImplicationOur study demonstrates that hazardous water pollutants, including microbial contamination, nutrient enrichment, and chemical stressors, vessel pressure, show strong, species-specific impacts on resident cetaceans in Hong Kong. By integrating eDNA metabarcoding with joint species distribution models, we provide a diagnostic framework that directly links pollutant profiles to ecological risk. These findings highlight that conventional conservation strategies overlooking pollution drivers are insufficient for marine megafauna persistence. Our approach offers an early-warning system for monitoring hazardous pollutants in coastal ecosystems and supports adaptive management strategies to mitigate biodiversity loss in urbanized seascapes.

ecology↗

bioRxiv2025

Autonomous Reef Monitoring Structures (ARMS) Reveal Human-Induced Biodiversity Shifts in Urban Coastal Ecosystems

Biodiversity thrives in coastal marine habitats which host foundational species such as corals, mangroves, and seagrasses. However, coastal development and the growth of megacities along shorelines impose an array of stressors on the marine environment. These stressors inevitably impact biodiversity which dictates ecosystem functions and services. Despite extensive research on biodiversity responses to anthropogenic stressors, phylum-specific resistance and resilience dynamics - particularly in coastal marine ecosystems - remain poorly understood. Considering the global scale of coastal development, it is imperative to develop a more comprehensive understanding of how biodiversity, in terms of richness and community composition, is influenced by various anthropogenic stressors. Here, we present the first application of standardized Autonomous Reef Monitoring Structures (ARMS) as an experimental unit - using a common garden experimental design - to examine community responses to stress within an urbanized seascape. ARMS were seeded within two marine reserves for one year and then transplanted to sites of stress, including domestic sewage, and mariculture. We hypothesized that 1) human impacts reduce richness and alter composition of established communities; and 2) increasing intensity of these impacts reduces community resistance and resilience to stress. Using metabarcoding, we quantified richness and taxonomic composition and assessed their changes along an impact gradient. Our results showed that nutrient pollution, particularly inorganic nitrogen, significantly reduced species richness and restructured communities. Communities exhibited low resistance, yet high resilience - suggesting that urbanized seascapes have high recovery potential when stress is mitigated.

ecology↗

bioRxiv2024

Trophic niche partitioning in symbiotic marine invertebrates

Fierce competition for food and space underpins coral reefs biodiversity - supported by photosymbiotic foundational species. In contrast to other ecosystems, there is scant evidence that competition is mitigated by niche partitioning. Indeed, the dynamic evolutionary lineages of symbiotic partners and their syntrophy create layers of nutritional complexity that obfuscate patterns that structurn reef communities. As conspicuous members of Indo-Pacific reefs - giant clams co-occur with reef-building corals and similarly associate with algal symbionts. Using a common garden experiment, we analyzed stable isotope values from six giant clam species in the Philippines. These data, along with published data from ten sympatric corals, were used to calculate a novel metric - the Host Evaluation: Reliance on Symbionts (HERS) index - to assess variations in relative trophic strategies. Consistent with trophic niche partitioning - all species fell along an autotrophy-heterotrophy gradient with little overlap. We found a significant phylogenetic signal in clam HERS score, highlighting the role of selection in their nutritional ecology. We conclude that niche partitioning comes with tradeoffs, where predominantly autotrophic species showed higher growth rates but higher susceptibility to stress and consequently - greater conservation concern. TeaserTrophic niche partitioning plays a role in symbiotic marine invertebrate evolution with benefits and costs.

ecology↗