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Abstract Purpose The ecological interdependence between macroorganisms and their microbial communities promotes stable associations over time, potentially leading to their evolutionary co-diversification. The detection of intricate eco-evolutionary interactions between animals and their microbiota is challenging, primarily due to complex bacterial communities related to poorly resolved host population structure. Strikingly, co-diversification in invertebrates, characterized by generally less complex microbiota, remains largely unexplored. Here, we compared the bacterial communities associated with two distinct lineages of Nacella limpets, a dominant shallow water patellogastropod of the Southern Ocean shores with a well-described population structure. Our goals were to elucidate the uniqueness of Nacella microbiota, resulting from an ecological filter that selectively favors certain bacterial taxa. Additionally, we aimed to depict the genetic structure of bacterial symbiont seeking evidence of co-diversification with Nacella. Methods We sequence the V4-V5 regions of the bacterial 16S rRNA gene in three distinct microenvironments associated with Nacella: rock substrate, radula, and whole intestine. These samples were collected from two populations of Nacella deaurata and Nacella concinna, located in the West Antarctic Peninsula and Falkland/Malvinas Islands, respectively. Results We assessed ecological filtering patterns in the limpet microbiota, uncovering unique bacterial communities in both radulas and intestines, with specifically enriched bacterial taxa compared to the surrounding environment. By examining microdiversity patterns of core bacterial taxa, we revealed a deep phylogeographic structure of Psychrilyobacter in Nacella intestines. Conclusion We highlight the Southern Ocean limpets of the Nacella genus as a novel and promising model for studying co-diversification between marine mollusks and their resident microbiota.

Purpose: The ecological interdependence between macroorganisms and their microbial communities promotes stable associations over time, potentially leading to their evolutionary co-diversification. The detection of intricate eco-evolutionary interactions between animals and their microbiota is challenging, primarily due to complex bacterial communities related to poorly resolved host population structure. Strikingly, co-diversification in invertebrates, characterized by generally less complex microbiota, remains largely unexplored. Here, we compared the bacterial communities associated with two distinct lineages of Nacella limpets, a dominant shallow water patellogastropod of the Southern Ocean shores with a well-described population structure. Our goals were to elucidate the uniqueness of Nacella microbiota, resulting from an ecological filter that selectively favors certain bacterial taxa. Additionally, we aimed to depict the genetic structure of bacterial symbiont seeking evidence of co-diversification with Nacella. Methods: We sequence the V4-V5 regions of the bacterial 16S rRNA gene in three distinct microenvironments associated with Nacella: rock substrate, radula, and whole intestine. These samples were collected from two populations of Nacella deaurata and Nacella concinna, located in the West Antarctic Peninsula and Falkland/Malvinas Islands, respectively. Results: We assessed ecological filtering patterns in the limpet microbiota, uncovering unique bacterial communities in both radulas and intestines, with specifically enriched bacterial taxa compared to the surrounding environment. By examining microdiversity patterns of core bacterial taxa, we revealed a deep phylogeographic structure of Psychrilyobacter in Nacella intestines. Conclusion: We highlight the Southern Ocean limpets of the Nacella genus as a novel and promising model for studying co-diversification between marine mollusks and their resident microbiota. [ABSTRACT FROM AUTHOR]

Background and Aims Worldwide, invasive species are spreading through marine systems at an unprecedented rate with both positive and negative consequences for ecosystems and the biological functioning of organisms. Human activities from shipping to habitat damage and modification are known vectors of spread, although biological interactions including epibiosis are increasingly recognized as potentially important to introduction into susceptible habitats. Methods We assessed a novel mechanism of spread – limpets as transporters of an invasive alga, Sargassum muticum , into beds of the seagrass Zostera marina – and the physiological impact of its invasion. The association of S. muticum with three limpet species and other habitats was assessed using intertidal surveys on rocky shores and snorkelling at two seagrass sites in the UK. A 4-year field study tested the effect of S. muticum on Z. marina shoot density, dry weight and phenolic compounds (caffeic and tannic acid) content, and a laboratory experiment tested the impact of S. muticum on nutrient partitioning (C/H/N/P/Si), photosynthetic efficiency (F v/ F m) and growth of Z. marina. Results On rocky shores 15 % of S. muticum occurrences were attached to the shells of live limpets. In seagrass beds 5 % of S. muticum occurrences were attached to the shells of dead limpets. The remainder were attached to rock, to cobblestones, to the seagrass matrix or embedded within the sand. Z. marina density and phenolics content was lower when S. muticum co-occurred with it. Over 3 years, photosynthetic responses of Z. marina to S. muticum were idiosyncratic, and S. muticum had no effect on nutrient partitioning in Z. marina. Conclusions Our results show limpets support S. muticum as an epibiont and may act as a previously unreported transport mechanism introducing invaders into sensitive habitats. S. muticum reduced production of phenolics in Z. marina , which may weaken its defensive capabilities and facilitate proliferation of S. muticum. The effect of S. muticum on Z. marina photosynthesis requires further work but having no effect on the capacity of Z. marina to sequester nutrients suggests a degree of resilience to this invader. [ABSTRACT FROM AUTHOR]

The limpet Patella aspera is an endemic species to the Macaronesian Islands. Its high economic value and vulnerability to exploitation has triggered the interest in the development of its aquaculture. Significant progress has been made in recent years, with the establishment of artificial fertilization and larval production protocols. However, there are at least two major challenges that need to be addressed before a commercial production can be achieved: larval settlement and juvenile grow-out. The aim of this research was to study the effect of different algae substrates (Ulvella lens, Amphora sp., Entomoneis sp., Navicula salinicola and Nitzschia sp.) on P. aspera settlement and to test the effect of two diets on juvenile growth: a mono diet based on U. lens versus a mixed diet composed by U. lens and the diatoms Nitzschia sp. and Navicula salinicola. Results showed that U. lens was the most efficient settlement cue, given that 84.6% of the post-larvae obtained were found on this algae substrate. In the following trial, U. lens was selected as the base diet for the grow-out phase. The rearing system used ensured juvenile survival percentages above 80%. The regular supply of the diatom mixture, as a dietary supplement, significantly enhanced juvenile growth performance. After 220 days post fertilization, limpets that grew on the mixed diet (U. lens plus diatoms) presented an average shell length of 19.280 ± 5.296 mm. Additionally, developed gonads were observed in females with less than 8 months. This study presents the first record of P. aspera juvenile grow-out, born from artificial fertilization, which represents a major step toward the development of limpet aquaculture.

The influx of volcanic ash into seawater alters particle composition with implications for the cellular, physiological and anatomical response of suspension-feeding organisms. Adult females of Crepipatella peruviana were exposed to three diets consisting of a fixed concentration of 50,000 cells ml−1 of the microalga Isochrysis galbana plus different concentrations of ash particles (30, 90 and 150 mg L−1). The objective was to determine the cellular, physiological and anatomical responses. Mortality increased with ash concentrations, while feeding and respiration rates, tissue weight, and condition index decreased. The gills showed severe degradation of cilia and the presence of large mucous aggregates of cilia and ash. An increase in ash resulted in decreased lipid peroxidation and protein carbonyls, but increased total antioxidant capacity and phenols. Thus, volcanic ash particles may exert a high impact at both cellular and physiological levels for C. peruviana , where inhibition of gill function reduces the ability to acquire food. [Display omitted] • Volcanic ash entering water changes seston composition affecting suspension-feeders. • Ash in the sea water impact the physiological and cellular response. • Mortality increased with increasing ash concentrations in diet. • Volcanic activity can eliminate communities of water suspension-feeders. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) accumulation in rocky shore organisms has limited knowledge. This study investigated MPs accumulation in filter-feeding oysters, herbivorous limpets and carnivorous snails to assess their performance as sentinel species in the MPs trophic transfer. The samples were obtained along a contamination gradient in the Santos Estuarine System, Brazil. All three studied species showed MPs concentrations related to the contamination gradient, being the oysters the species that showed the highest levels, followed by limpets and snails (average of less and most contaminated sites of 1.06–8.90, 2.28–5.69 and 0.44–2.10 MP g−1, respectively), suggesting that MPs ingestion rates are linked to feeding habits. MPs were mainly polystyrene and polyacetal. The polymer types did not vary among sites nor species. Despite minor differences in percentages and diversity of size, shape, and color classes, the analyzed species were equally able to demonstrate dominance of small, fiber, transparent, black and blue MPs. Thus, oysters, limpets, and snails are proposed as sentinels of MPs in monitoring assessments. [Display omitted] • Oysters accumulated more microplastics (MPs) than limpets and snails. • Filter-feeders accumulated more MPs than herbivores and carnivorous. • All species similarly reflected the known contamination gradient. • Minor differences in MP types were seen spatially and among species. • Oysters, limpets and snails can be used as sentinels of MPs contamination. [ABSTRACT FROM AUTHOR]