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Zardi GI, Monsinjon JR, Seuront L, Spilmont N, McQuaid CD, Nicastro KR. Symbiotic endolithic microbes reduce host vulnerability to an unprecedented heatwave. MARINE ENVIRONMENTAL RESEARCH 2024; 199:106622. [PMID: 38936261 DOI: 10.1016/j.marenvres.2024.106622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 06/19/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024]
Abstract
Heatwaves are increasingly severe and frequent, posing significant threats to ecosystems and human well-being. Characterised by high thermal variability, intertidal communities are particularly vulnerable to heat stress. Microbial endolithic communities that are found in marine calcifying organisms have been shown to induce shell erosion that alters shell surface colour, lowering body temperatures and increasing survival rates. Here, we investigate how the symbiotic relationship between endolithic microbes and the blue intertidal mussel Mytilus edulis mitigates thermal stress during the unprecedented 2022 atmospheric heatwave in the English Channel. Microbial infestation of the shell significantly enhanced mussel survival, particularly higher on the shore where thermal stress was greater. Using data from biomimetic temperature loggers, we predicted the expected thermal buffer and observed differences up to 3.2 °C between individuals with and without symbionts under the known conditions of the heat wave-induced mortality event. The ecological implications extend beyond individual mussels, affecting the reef-building capacity of mussels, with potential cascading effects for local biodiversity, carbon sequestration, and coastal defence. These findings emphasize the importance of understanding small-scale biotic interactions during extreme climate events and provide insights into the dynamic nature of the endolith-mussel symbiosis along a parasitic-mutualistic continuum influenced by abiotic factors.
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Affiliation(s)
- Gerardo I Zardi
- Normandie Université, UNICAEN, Laboratoire Biologie des Organismes et Ecosystèmes Aquatiques, UMR, 8067 BOREA, (CNRS, MNHN, UPMC, UCBN, IRD-207), CS 14032 14000, Caen, France; Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa; CCMAR-CIMAR - Associated Laboratory, University of Algarve, Campus de Gambelas, Faro, 8005-139, Portugal
| | - Jonathan R Monsinjon
- Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa
| | - Laurent Seuront
- Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa; Univ. Lille, CNRS, Univ. Littoral Côte D'Opale, IRD, UMR, 8187 - LOG - Laboratoire D'Océanologie et de Géosciences, F-59000, Lille, France; Department of Marine Resources and Energy, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo, 108- 8477, Japan
| | - Nicolas Spilmont
- Univ. Lille, CNRS, Univ. Littoral Côte D'Opale, IRD, UMR, 8187 - LOG - Laboratoire D'Océanologie et de Géosciences, F-59000, Lille, France
| | - Christopher D McQuaid
- Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa
| | - Katy R Nicastro
- Department of Zoology and Entomology, Rhodes University, Grahamstown, 6140, South Africa; Univ. Lille, CNRS, Univ. Littoral Côte D'Opale, IRD, UMR, 8187 - LOG - Laboratoire D'Océanologie et de Géosciences, F-59000, Lille, France; CCMAR-CIMAR - Associated Laboratory, University of Algarve, Campus de Gambelas, Faro, 8005-139, Portugal.
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Ma KCK, Monsinjon JR, Froneman PW, McQuaid CD. Thermal stress gradient causes increasingly negative effects towards the range limit of an invasive mussel. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 865:161184. [PMID: 36581263 DOI: 10.1016/j.scitotenv.2022.161184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 12/16/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
Environmental filtering (EF), the abiotic exclusion of species, can have first order, direct effects with cascading consequences for population dynamics, especially at range edges where abiotic conditions are suboptimal. Abiotic stress gradients associated with EF may also drive indirect second order effects, including exacerbating the effects of competitors, disease, and parasites on marginal populations because of suboptimal physiological performance. We predicted a cascade of first and second order EF-associated effects on marginal populations of the invasive mussel Mytilus galloprovincialis, plus a third order effect of EF of increased epibiont load due to second order shell degradation by endoliths. Mussel populations on rocky shores were surveyed across 850 km of the south-southeast coast of South Africa, from the species' warm-edge range limit to sites in the centre of their distribution, to quantify second order (endolithic shell degradation) and third order (number of barnacle epibionts) EF-associated effects as a function of along-shore distance from the range edge. Inshore temperature data were interpolated from the literature. Using in situ temperature logger data, we calculated the effective shore level for several sites by determining the duration of immersion and emersion. Summer and winter inshore water temperatures were linked to distance from the mussel's warm range edge (our proxy for an EF-associated stress gradient), suggesting that seasonality in temperature contributes to first order effects. The gradient in thermal stress clearly affected densities, but its influence on mussel size, shell degradation, and epibiosis was weaker. Relationships among mussel size, shell degradation, and epibiosis were more robust. Larger, older mussels had more degraded shells and more epibionts, with endolithic damage facilitating epibiosis. EF associated with a gradient in thermal stress directly limits the distribution, abundance, and size structure of mussel populations, with important indirect second and third order effects of parasitic disease and epibiont load, respectively.
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Affiliation(s)
- Kevin C K Ma
- Department of Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa; Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada.
| | - Jonathan R Monsinjon
- Department of Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa; Ifremer, Indian Ocean Delegation, Le Port, La Réunion, France
| | - P William Froneman
- Department of Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa
| | - Christopher D McQuaid
- Department of Zoology and Entomology, Rhodes University, Grahamstown, Eastern Cape, South Africa
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