Freezing temperatures drive functional trait clustering more than habitat structure in eelgrass communities in the Gulf of Maine
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Understanding the processes that determine community assemblage—the identity of the mechanisms, relative strengths, and patterns—is a central question in community ecology. Processes of community assemblage may vary over space and time as environmental and biological pressures change. Functional traits quantify the niche space of each species, which can elucidate redundancies or complementarity of traits within a community. The level of redundancy in traits is referred to as trait clustering. While trait clustering has been used on a global scale, local scale uses are understudied and may prove helpful in uncovering assembly processes that occur on small spatial scales. In this study, I use Zostera marina meadow ecosystems to explore patterns in functional trait clustering across small spatial scales (<75 >km). I investigate epifaunal species, which are a linchpin in Z. marina meadows. Temperature 3-months before sample collection explains up to 58% of variation in trait clustering. Shoot density and shoot height are significantly associated with trait clustering; there is a pattern of over-dispersion associated with taller, denser shoots. Trait distribution in the Downeast region of Maine was more clustered than Southern Maine. 3 sites, Mackworth Island, Holmes Cove, and Little Mathias Bay, all had communities more clustered than the null expectation. Detecting community assembly processes that alter functional trait clustering on small spatial scales has implications for the relative vulnerability of sites to environmental impact and anthropogenic change. Sites that are more clustered are more resistant to change but have less ability to recover from disturbance.
Available for download on Monday, May 18, 2026