Coastal upwelling affects filter-feeder stable isotope composition across three continents

Area of Science:

• Marine Ecology
• Oceanography
• Biogeochemistry

Background:

• Coastal upwelling delivers nutrients, enhancing phytoplankton production and supporting benthic ecosystems.
• Climate change is predicted to alter coastal upwelling patterns, with unknown consequences for marine food webs.

Purpose of the Study:

• To investigate the impact of coastal upwelling on the diets of key benthic consumers, Perna perna and Mytilus galloprovincialis.
• To assess how upwelling intensity and frequency influence the stable isotope signatures of these mussels across different global regions.

Main Methods:

• Stable isotope analysis (δ13C) of Perna perna and Mytilus galloprovincialis tissues.
• Comparison of mussel isotopic composition between upwelling and non-upwelling sites in five distinct upwelling systems (Brazil, South Africa, Oman, North West Africa, and Western Australia).

Main Results:

• Mussels at upwelling sites generally showed lower δ13C values, indicating a diet enriched in upwelling-derived carbon.
• The effect was more pronounced in regions with more intense and frequent upwelling.
• Variability in North West Africa was potentially influenced by Saharan dust input.

Conclusions:

• Coastal upwelling is crucial for sustaining benthic primary consumers like mussels.
• Mussel diets are sensitive to the intensity and frequency of upwelling, highlighting regional differences.
• Climate change-driven alterations in upwelling could have cascading effects on higher trophic levels and ecosystem functioning.