Estuaries are among the most productive ecosystems and provide habitats for many commercially and recreationally important species (e.g. oysters, crabs and shrimp). They are also active sites of sediment organic matter decomposition and associated nutrient regeneration.
Invertebrates living in estuaries sediment play important roles in coastal ecosystems through their impact on nutrient cycling and by serving as an important trophic link. Due to their restricted mobility, invertebrates have limited ability to avoid environmental and human disturbances, including eutrophication, hypoxia, salinity fluctuations and sediment resuspension resulting from storms and tides. As a result, they can be particularly impacted by stressors that occur in estuarine ecosystems.
Shallow coastal sediments can act as either a source or sink for nutrients. Nutrients regenerated in sediments can be a substantial component of those required for primary production in the water column. Through their activities of bioturbation (see video below), feeding, burrowing, irrigation of burrows, excretion of wastes and locomotion, invertebrates can enhance the exchange of materials between the sediment and overlying water column and modify sediment redox conditions. As a shallow estuarine ecosystem experiencing high anthropogenic nitrogen loads, Mobile Bay, Alabama, is an ideal system in which to study the macrofaunal influence on sediment nutrient cycling.
