Contrasting Traits of Common Molluscan Species Across Sites With Different Distances From Nutrient Sources in a Patagonian Bay

ABSTRACT

Nutrient enrichment is a known threat to coastal ecosystems, yet detecting its biological impacts remains challenging. This study evaluated the variation in population and individual traits of three mollusks, Brachidontes rodriguezii , Bostrycapulus odites , and Buccinastrum deforme, in a eutrophic bay (40°42′ ‐ 40°50′ S/64°43′ ‐ 65°07′ W, Patagonia, Argentina) during 2021, across sites that differed in their proximity to the main anthropogenic source of pollution. The small mussel B. rodriguezii exhibited lower densities but significantly increased individual traits (larger size, higher weight, better condition index, and relative thickness) in the site closest to the source of nutrient pollution. Moreover, B. rodriguezii showed significant differences in the length–weight relationship among sites, with individuals showing higher growth rates in the site closest to the source of nutrient pollution. These findings suggest that individual‐level traits may reflect the benefits of increased food availability, even when population‐level metrics such as density decline. In contrast, the slipper limpet B. odites exhibited no clear variation across sites, while the scavenger snail B. deforme was absent in the distant site and only showed slight individual differences in the site closest to the main source of pollution. Overall, our results highlight B. rodriguezii as a promising candidate for monitoring nutrient‐driven changes in these coastal benthic communities and emphasize the importance of species‐specific traits in shaping mollusk variations to nutrient pollution.