MEPS 626:83-96 (2019)  -  DOI: https://doi.org/10.3354/meps13059

ABSTRACT: Geochemical signatures in calcified structures of marine organisms have been widely used as environmental markers and natural tags, reflecting seawater characteristics and allowing the study of larval dispersal patterns. However, the role of environmental, biological and physiological factors in the incorporation of trace elements in carbonate structures is still not fully elucidated. Here, we investigated the effects of temperature and salinity on the incorporation of several elements (²³Na, ²⁴Mg, ⁴⁸Ca, ⁵⁵Mn, ⁶³Cu, ⁸⁸Sr and ¹³⁷Ba) in larval shells of Mytilus galloprovincialis. Larvae were cultured in the laboratory under different temperatures (12, 17, 20°C) and salinities (26, 32, 37) in a factorial design. Results showed an enrichment of Na/Ca, Sr/Ca and Cu/Ca ratios in shells under low salinity and high temperature treatments. Mg incorporation in the shell was also affected by temperature. Mn/Ca and Ba/Ca were the only elements with no clear relationship to the factors tested, indicating lower physiological control and/or alternative pathways for incorporation. Our results suggest the need for careful interpretation in the use of geochemical structures as environmental proxies due to the high physiological control over shell deposition. Nonetheless, temperature and salinity effects on shell composition can contribute to finding differential tags between habitats with similar elemental availability. Understanding the underlying mechanisms of element incorporation into larval shells constitutes crucial baseline information to interpret environmental signatures in ecological studies.

KEY WORDS: Geochemical signatures · Larval shells · Temperature · Salinity · Mytilus galloprovincialis · Physiological control