Blue mussel shell shape plasticity and natural environments: a quantitative approach

Area of Science:

• Marine Biology
• Ecology
• Evolutionary Biology
• Biogeography

Background:

• Organismal shape variability is a key adaptation to environmental pressures.
• Blue mussels (Mytilus edulis and M. trossulus) are ecologically significant bivalves found globally.
• Understanding shell shape variation is crucial for assessing population health and environmental change impacts.

Purpose of the Study:

• To investigate spatial patterns of shell shape variation in North Atlantic and Arctic blue mussels.
• To identify the influence of environmental gradients (temperature, salinity, food availability) on mussel shell morphology.
• To decouple developmental and genetic contributions to shell shape and establish general environmental relationships.

Main Methods:

• Employed geometric morphometrics to quantify shell shape.
• Utilized generalised additive mixed models (GAMMs) to analyze environmental influences.
• Studied 3980 km of coastlines across multiple geographical scales.

Main Results:

• Salinity exhibited the strongest effect on latitudinal shell shape patterns, with lower salinities correlating to more elongated, narrower shells.
• Temperature and food availability were identified as primary drivers of mussel shell shape heterogeneity.
• Consistent shell shape responses to unfavorable environmental conditions were observed across different scales and species.

Conclusions:

• Blue mussel shell shape is highly plastic and sensitive to environmental conditions.
• Shell shape plasticity serves as a potent indicator for monitoring blue mussel community health in changing environments.
• Environmental factors significantly shape mussel shell morphology, independent of age and species.