Document Type

Article

Publication Date

2025

DOI

10.1007/s00227-025-04739-9

Publication Title

Marine Biology

Volume

172

Issue

12

Pages

188

Abstract

Climate change is expected to intensify salinity and temperature fluctuations in estuarine and coastal habitats. However, the impact of salinity variation on ectotherms’ thermal tolerance remains underexplored, limiting our understanding of the interplay between these stressors. This study investigated salinity-dependent changes in life history traits (survival, growth rate, fecundity, and egg size) over a 33-day exposure to a salinity gradient (12, 17, 22, 27, 32, 35, 40, 45, 50) in the marine annelid Ophryotrocha labronica. Individuals that survived the salinity treatments were assessed for their upper and lower thermal tolerance limits. Female individuals, the target of the study, exhibited a relatively broad optimal salinity range for reproduction and growth (22–35), with comparable survival rates across the remaining salinity treatments (12–45). Declining performance was observed towards the extremes of the gradient, with the highest salinity (50) proving lethal within 2–3 days of exposure. The decline in fecundity observed at the lowest (12) salinity was associated with a reduction in upper thermal tolerance limits and growth rates, as well as an increase in egg size. Cold tolerance remained consistent across treatments, while heat tolerance remained unchanged at the highest salinities. Our study demonstrates that salinity variation affects the heat tolerance and reproductive traits of O. labronica, with adjustments primarily driven by low salinities. These adaptations may contribute to the species’ extended survival under suboptimal conditions. Our findings contribute to the debate on the role of salinity-dependent thermal tolerance in determining the ability of marine organisms to cope with changing temperature conditions.

Rights

© The Authors 2025.

This article is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original authors and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder

Data Availability

Article states: "Data will be made available in public repository upon acceptance of paper."

Original Publication Citation

Newton, G., & Massamba-N'Siala, G. (2025). Low salinities impair heat tolerance and alter reproductive traits with no implications for survival in a marine annelid from coastal habitats. Marine Biology, 172(12), Article 188. https://doi.org/10.1007/s00227-025-04739-9

ORCID

0000-0003-0904-5208 (Massamba-N'Siala)

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