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Benthic Habitat Mapping to Understand Ecosystems

The Cape Cod Maritime Museum hosted a discussion of keystone species and benthic habitat mapping called “Cape Cod’s Marine Food Webs” by Dr. Agnes Mittermayr, a marine ecologist, on December 19, 2021. Our world’s ecosystems and the species within them are interconnected; navigating environmental issues and beginning restoration efforts first requires understanding how an ecosystem functions. Keystone species are species in an ecosystem that connect to all the other species present; removal of this species would cause drastic changes in the ecosystem. Protecting keystone species is so important because it ensures the health of the entire ecosystem. Mittermayr found the keystone species in an underwater eelgrass bed ecosystem to be a species of amphipod, a small invertebrate (2021). Despite their size, these species play a vital role to many food webs because if amphipods are threatened fish populations may starve or move away, and algae overgrowth could lead to anoxic waters (Mittermayr, 2021). Protecting the amphipods along the New England coast will encourage productivity in our marine ecosystems.

Studying marine food webs can be more challenging than terrestrial ones because of the extra tools and resources needed. One technique that can be used to evaluate the health of a marine ecosystem is known as benthic habitat mapping. The benthic zone of a waterway is at the lowest level, the seafloor. This zone is home to many small invertebrates and is full of nutrients. Seagrass and other organisms in the seafloor influence the water column, likewise organisms moving in the water influence the benthic zone (Mittermayr, 2021). Benthic habitat maps are a type of biotype habitat map that include specific structural components to model the aquatic ecosystem. These maps provide a topographic view of the seafloor, a map of the substrate grain size, a map of species diversity taken directly from biota samples, and information about the water column (Mittermayr, 2021). Using these maps provides one with critical information on the health of keystone species and other life in the water column. Benthic habitat maps can also be used as a tool to measure the progress of restoration efforts. For example, habitat fragmentation is a human caused environmental issue. A dam is an artificial reservoir that restricts water flow in the downstream direction. It has been proven with benthic habitat mapping that dam removal is an effective tool for steam restoration (Mehan et al., 2021). Species richness and species density increased after dams were removed in a Michigan river (Mehan et al., 2021).

There are over 3000 dams in Massachusetts which, if removed, would improve river and stream health by allowing fish to move through watersheds, creating an increase in dissolved oxygen, and removing stagnant conditions from the water column and benthic zones. (Division of Ecological Restoration, n.d.). The Massachusetts Division of Ecological Restoration website models the ecological improvement to a river if a dam were removed, and will help dam owners with removal (Division of Ecological Restoration, n.d.). Increasing awareness of the negative impact dams have on ecosystems will encourage their removal and river restoration.


Division of Ecological Restoration. (n.d.). River restoration: Dam removal.

Retrieved April 10, 2022, from

Mahan, D. C., Betts, J. T., Nord, E., Van Dyke, F., & Outcalt, J. M. (2021). Response of

benthic macroinvertebrates to dam removal in the restoration of the Boardman

River, Michigan, USA. PLoS ONE, 16(5), 1–19.

Mittermayr, A. (2021 Dec 19). Cape Cod’s Marine Food Webs [Webinar]. Cape Cod

Maritime Museum.


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