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Eelgrass response to Changing Environmental Drivers: Lessons from PNW Mesocosm Studies
Citation:
Kaldy, Jim. Eelgrass response to Changing Environmental Drivers: Lessons from PNW Mesocosm Studies. HMSC Thursday Seminar, Newport, Oregon, April 19, 2018.
Impact/Purpose:
This presentation describes research on how estuarine plants respond to nutrient and thermal stressors. These studies suggest that increased water temperature is generally more detrimental to eelgrass than increased nutrient loading. Warm water temperatures increase the susceptibility of eelgrass to wasting disease, while one recently proposed monitoring indicator (Nutrient Pollution Index) did not accurately reflect nutrient loading at warm temperatures. Further, preliminary data suggest that eelgrass loss due to “nitrate toxicity” may be related to extreme carbon limitation and not a direct toxicity response. Unique characteristics of PNW estuaries may make them less vulnerable to nutrient issues, but thermal stress consistently reduced plant performance. Understanding how multiple stressors impact the health and productivity these plants provide is critical to the restoration and conservation of estuarine seagrass habitat. Seagrasses are important nurseries for many fish and shellfish as well as acting as a biological filter for nitrogen and carbon.
Description:
Seagrass communities are ecosystem engineers that provide important services in a dynamic estuarine environment. Seagrass is often seen as a sentinel species or indicator of estuarine health. Estuaries are increasingly impacted by natural and anthropogenic stressors, and loss of critical seagrass habitat has been documented at the local, regional, national and global scale. The interaction of 3 “master variables”, light temperature and nutrients generally control seagrass health and productivity. Despite more than 30 years of work, our understanding of how these variables interact to influence seagrass productivity is still rather rudimentary. This presentation synthesizes my research on how native eelgrass Zostera marina L. responds to nutrient and thermal stressors across the scale of individuals to simulated communities and highlights some unexpected results.