Description | Talk Title: Our new understanding of dead-shell assemblages: A powerful tool for deciphering human impacts One of the big challenges in environmental management and conservation biology is discovering ‘what was natural’ before human impacts. This problem is especially pressing in marine systems, where direct monitoring of conditions is usually short relative to the span of cultural stressors or is lacking for key variables. Geological analysis of molluscan death assemblages – the dead shells sieved from the top 10-15cm of the seabed during biological surveys – is demonstrating that they are a powerful means of detecting, in the absence of direct observations, benthic response to a wide array of human stressors, such as anthropogenic eutrophication, bottom trawling, and dredge-spoil dumping. The densely monitored coast of urban southern California provides a wonderful study area for testing the limits of this approach. Even here, “live-dead comparison” and “age-unmixing” of skeletal debris has revealed a completely unsuspected transformation of the mainland shelf ecosystem, driven by shifting landuse and completed decades before monitoring began, suggesting new priorities for protection and new benchmarks for gauging recovery. |
---|