Estuary Ecology 101

The Damariscotta River Estuary: Heirloom Habitats Rich with Life

Estuaries, places where freshwater flows off the land and mixes with the ocean’s salt water, are constantly changing. Tides, freshwater streams and weather replenish water and nutrients regularly: nourishing life, mixing sediments and eroding the rocks over time.

Greater Than the Sum of its Parts

Natural systems, like the Damariscotta River Estuary watershed, provide critical services including, nutrient cycling, carbon sequestration, water purification, pollination, and erosion control.

Furthermore, estuaries everywhere provide critical nursery grounds for fish, migration stop-over habitat, and feeding grounds for a wide variety of wildlife.

(photos: American lobster eat a wide variety of foods and thus are important in nutrient cycling processes. Like all trees, Red Spruce sequesters carbon, which is critical in global climate regulation. Phytoplankton, like Gyrosigma sp.,  provide around 60% of the earth’s oxygen.

Strengthened by Diversity

The Gulf of Maine Council has identified some plants and animals as having special ecological and economic importance to this region. Of these “species of significance” to the Gulf of Maine ecosystem, 20% live in the Damariscotta River Estuary. Without biological diversity, this ecosystem could not provide the essential services that keep the estuary functioning. (Photos: Sea urchin, sea anemone, Artic Tern, Black Duck, American Woodcock, and Osprey all contribute to cycles and processes that keep the estuary healthy and are examples of “species of significance.”)

Ancient Species Contribute to the Estuary Today

Relic species, including red-beard sponge and horseshoe crabs, were isolated here after the last ice age as the waters of this shallow estuary warmed, and then cooled again over thousands of years. Each of these species plays an important role in this ecosystem by contributing to the critical services. (photo:  Horseshoe crabs are one of the “relic species” found in the Damariscotta Estuary. With the exception of Taunton Bay this is the most northerly concentration of horseshoe crabs.

By protecting the key assets of the Damariscotta River Estuary watershed we ensure that biological diversity is maintained and the entire system functions efficiently. A reduction of even one of the key assets could have a cascading, negative impact on the whole estuary. This highlights the importance of thoughtful stewardship that focuses on the complicated relationships of plants and animals in their environment.

What are the Key Assets of an ecosystem?

Clean Water

Water free of toxins and suspended sediment supports life by transporting oxygen and nutrients.

(phytoplankton photo) Phytoplankton are microscopic plants that are the foundation of the ocean’s food web.

Keystone Species

Species which provide several functions within the ecosystem and are disproportionally influential, may warrant special protection.

(Oyster photo) Oyster reefs provide places for fish to hide, a natural water filtering system, food for birds and other wildlife, and sediment stabilization.

Wildlife Corridors

Migratory pathways for plants and animals allow for seasonal movement and response to climate change. Without these corridors, species can become isolated and susceptible to disease and genetic restriction.

(Dragonfly Photo) Dragonflies, butterflies, fish and many birds depend on a variety of habitats as they migrate.

Web of Life

In addition to predator and prey relationships, plants and animals depend on each other for transportation, shelter, nutrients, seed dispersal, and pollination.

(Alewife/Floater photos) The alewife floater is a freshwater mussel that must travel on the gills of an alewife during its larval stage. It cannot survive without the fish, which provides the mussel with a dispersal mechanism.

Biological Diversity

Habitats with a wide variety of plants and animals tend to be resilient to change and provide the greatest number of essential services.

Forests with multi-layered canopies and healthy understories provide the structure for biological diversity. (Forest photo)