Nearshore Ecology

The nearshore is a highly productive zone of the ocean. At Calvert, the complex, convoluted shoreline juxtaposes high-energy exposed rocky reefs with sheltered channels and muddy bays.  Habitat-forming species along these coasts are adapted to the dynamic influx of bog and snowpack-fed freshwater, and oceanic water fed from far away by ocean currents. This confluence leads to rich and almost bewildering levels of biodiversity.

While all life deserves our attention, certain species are particularly important for healthy and resilient ecosystems. No species are more important than foundation species. A foundation species creates, maintains, and physically structures its environment, providing the habitat and essential resources that sustain many other species.

At the Calvert Coastal Observatory, we study foundation species in great detail, over the long term, across three habitats that make up our nearshore seascape.

Kelp Forests

The forests of the nearshore. We have rich stands of  the two canopy-forming foundation kelp species: giant kelp (Macrocystis pyrifera) and bull kelp (Nereocystis luetkeana). Below their canopies lies a rich diversity of sub-canopy kelps and seaweeds, invertebrates and fish. These underwater forests provide homes for commercially and culturally valuable species like rockfish and lingcod. Their large stipes and blades baffle the coast from winter storms. They grow at incredibly fast rates, taking up carbon dioxide as they elongate through the water column.

Seagrass Meadows

The grasslands of the nearshore. We have large beds of eelgrass (Zostera marina) growing in the more protected sandy and muddy shores around Calvert Island. Seagrass habitats protect the shoreline by reducing currents and accreting sediments. They also filter nutrients, sediments and pathogens from the water. They provide an important refuge for the early life stages of many marine critters, and support a rich area of invertebrates like crabs and clams.

Rocky Shores

The weather-beaten rocky outcrops of the nearshore. Bedrock, boulders and cobbles dominate the wave-exposed coastline of Calvert Island. The foundation species of these shores are arrayed in banded patterns on the rock, structured by the tide. In the high intertidal, the common seaweed Fucus is adapted to withstand heat and desiccation stress when exposed at low tide. In the mid zone, mussel beds create a complex habitat of crevices, where many small creatures set up shop to withstand the pounding surf. And exposed at the lowest of low tides, the surfgrass Phyllospadix and other seaweeds, cover the rocks, creating a slippery surface for human visitors. Surfgrass, Fucus and mussels cycle nutrients, provide habitat and feed the base of marine food webs in the nearshore and connected coastal waters.

Seascape Biodiversity

Across habitats - kelp forests,  seagrasses and rocky shores - charismatic foundation species may dominate, but let's not forget all the others that enrich the nearshore. At last count, we've recorded 353 seaweed species at Calvert--more than anywhere else on the west coast of North America.  Our scientists have also documented rich diversity in other groups - over 25 species of sea stars and 150 species of fish!

We celebrate and catalogue this biodiversity via our biodiversity bioblitzes and broad-focused habitat surveys. It is easy to get lost in the celebration of the beauty and complexity of it all.

Ecosystem Dynamics

Foundation species are undeniably important. They are also remarkably variable. Any change to a foundation species can have widespread consequences for myriad other species in the nearshore habitats.

Of course, all nearshore species are affected by changing ocean conditions - temperature, acidification, hypoxia, extreme weather. The case of kelp forest dynamics showcases the important interplay between the environment and the delicate balance of marine food webs. Sea urchins are voracious predators on kelps. Left unchecked, they will proliferate rapidly, eventually eliminate all kelp, and shift kelp ecosystems to what are known as urchin barrens.

An ecological balance is maintained when urchins are kept in check by their natural predators, mainly sea otters and sea stars at Calvert Island. Sea urchins and sea stars are known as "keystone predators" because removing them causes the fragile kelp forest ecosystem to collapse. A healthy, resilient, and productive ecosystem occurs when sea urchins, sea otters, and sea stars are in a dynamic balance, supporting vigorous kelp forests.

Sea otters were hunted to local extinction in the region around Calvert more than 200 years ago. In recent decades, populations have recovered, and rafts of sea otters have sporadically returned to the area. Each time they come back, we see an immediate and dramatic decline in the sea urchin population and a corresponding rebound of kelp and many other macrophytes, and a cascade of dependent species.

Sea stars, especially the sunflower sea star Pycnopodia helianthoides, are highly mobile predators that hunt many nearshore species, including sea urchins. Over the past decade, they and other sea stars have almost disappeared from the North American coast due to a deadly bacterial pandemic called sea star wasting disease (SSWD). As a result, urchin numbers have surged, leading to the destruction of kelp forests along the coasts of California, Oregon, and Washington. Some populations still remain in our study areas around Calvert Island, which has allowed us to take the lead in studying and understanding SSWD - a major disturbance to nearshore ecosystem dynamics.