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by Erin Loury
To enter the swaying, underwater fronds of a kelp forest is to see a marine ecosystem in action. Look closely, and you will find evidence of the many functions and processes at work that make giant kelp Macrocystis pyrifera a classic example of ecosystem goods and services. Kelp plays a variety of ecological and economic roles, making it a key species to consider during the process of marine spatial planning.
Human activities in the marine environment, such as recreation, transportation, resource extraction and military defense, sometimes overlap and degrade valuable marine ecosystems. Marine spatial planning is a decision-making process designed to organize the spatial placement of marine and coastal activity in a way that balances many human uses with ecosystem functioning and services. The Center for Ocean Solutions (COS) believes that marine spatial planning should be ecosystem-based and informed by the best scientific understanding of marine ecosystems, as well as economic, political and social guidelines.
Building an ecosystem-based framework for marine spatial planning first requires defining key features that are essential for maintaining ecosystem health and functioning. To that end, a recent paper published by COS scientists, legal scholars and affiliated researchers outlined several ecological principles that should guide marine spatial planning. These include maintaining or restoring the diversity of native species, the diversity and complexity of habitats, populations of key species, and connectivity. Defining these ecological principles will give resource managers more concrete guidelines for the placement of marine activities as well as clearer management objectives.
Kelp forests embody many of these ecological principles and are some of the most biologically diverse marine ecosystems, in part because of the crucial habitat they provide. Every part of a kelp plant’s structure plays an important ecological role, making it a key “foundation species” in the ecosystem. The intricate web of the holdfast, which anchors the kelp to its rocky substrate, offers high-density living space for a diversity of marine invertebrate tenants. The long stem-like stipe and leaf-like blades of the kelp stretch from the seafloor to the surface, creating a towering, three-dimensional structure in a watery world of mostly open space. Sedentary organisms like anemones, sponges and bryozoans colonize the kelp itself, while fishes take shelter amidst the undulating kelp canopy. The structure of a kelp forest can also diffuse and dampen powerful waves, buffering coastlines from the pounding effect of storm surges.
From the standpoint of marine spatial planning, kelp is considered a “key species” not just because of the valuable habitat it provides for a diversity of other species, but also because of its role at the base of the food web. Like their terrestrial relatives, kelps turn sunlight into energy, and provide a major source of primary production that fuels many coastal food webs. Herbivorous kelp crabs, snails and urchins graze on kelp tissue, and in turn become the food of fishes foraging in a colorful kelp forest buffet. Particulate and dissolved matter that sloughs off of dead kelp fronds also enter the food web, as do massive tangles of kelp that wash up onto the shore and provide nutrients to sandy beach organisms as they decay.
Humans too are drawn to kelp forests, in part for their beauty and the great diversity of life that they support. Kelp forests provide a gateway through which people can experience marine wildlife firsthand. Not only are kelp forests ingrained in the image of the rocky Pacific coast, they are popular places for recreation through kayaking, diving or fishing. People also harvest kelp for the algin it produces, a sugar that is used as a thickener and stabilizer in many products including ice cream and toothpaste.
The wealth of resources and services that kelp forests provide is an important example of how California’s long-term economic and environmental health depends on the health of ocean ecosystems. To ensure a sustainable and productive future for both people and the ocean, the Center for Ocean Solutions has engaged in marine spatial planning to find the right balance between human and ecological needs. Species like kelp that play many diverse roles crucial to both human and ocean success are therefore high on the priority list of important ecosystem goods and services to maintain.
Photos courtesy of Kendra Karr.
