Managing Nutrient Pollution in Coastal Ecosystems: Two Examples

Excess nutrients entering the ocean from sources like the runoff of agricultural fertilizers pose serious problems for coastal marine ecosystems.In some cases, hypoxic (low oxygen) 'dead zones' form, reducing marine biodiversity, fish habitat, and ultimately impacting fisheries (e.g., see here and here). Two well known examples of coastal ecosystems impacted by nutrient pollution are the Gulf of Mexico and Chesapeake Bay.

Two recent scientific papers provide interesting examples of different, but equally important approaches to the challenge of managing nutrient pollution, forecasting its impacts and assessing management actions intended to reduce it.

Ecosystem modeling is a valuable tool for evaluating trade-offs between environmental policies and management actions (e.g., see here). Evans and Scavia (2011) provide an example of the development and application of ecosystem models for predicting future hypoxic events in both Chesapeake Bay and the Gulf of Mexico. One goal of their analysis is to develop robust approaches to calibrating such models that optimize the accuracy and precision of forecasts for highly variable systems, such as the Bay and the Gulf, are changing over time.

Ruhl and Rybicki(2010) provide a different sort of analysis. Rather than using data to model and forecast future hypoxic conditions in Chesapeake Bay, they analyze past data from 18 years of restoration efforts to understand pattern of change observed in an indicator of ecosystem condition, Submerged Aquatic Vegetation(SAV) (see here). Contrary to general opinion about the ineffectiveness of such actions, their analysis suggests that, ". . . environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances."

Both papers are Open Access.

References for this post:

Evans, M.A. and D. Scavia. 2011. Forecasting hypoxia in the Chesapeake Bay and Gulf of Mexico: model accuracy, precision, and sensitivity to ecosystem change. Environmental Research Letters 6(1): doi: 10.1088/1748-9326/6/1/015001. O/A

Ruhl, H. A. and N. B. Rybicki. 2010. Long-term reductions in anthropogenic nutrients link to improvements in Chesapeake Bay habitat. Published online before print September 7, 2010, doi: 10.1073/pnas.1003590107. O/A