Modeling herbivorous consumer consumption in the Great Bay Estuary, New Hampshire

Herbivores play a vital role in eelgrass-based estuaries. They have been shown to alter plant productivity, distribution, and overall community structure. Epiphyte grazers are especially important as epiphytes compete with eelgrass for light and nutrients. For these reasons, a herbivorous consumer sector was constructed for a spatial ecosystem model developed for the Great Bay Estuary in New Hampshire (the Great Bay Model). There are three classifications used for consumers in the new sector: fast movers, slow movers, and sedentary. Defining this classification structure is the time needed to travel from one location to another. Criteria that determine movement include food availability and competition. Consumer ingestion is limited by metabolic activity, food preference, and food availability. Unit model results indicate that metabolic activity has a significant impact on consumption. Spatial results show an aggregation of consumers in areas of high food biomass. Travel time also appears to have a significant impact on the rate of growth of consumers. Future improvements to the model will incorporate bay competition between consumer groups as well as predator influence on herbivore behavior. The consumer sector should only be used as a framework for future development, pending available data.