Everything on earth grew from the sea. We are all beneficiaries of the blue-green algae (cyanobacteria) that invented photosynthesis. They lazed around in shallow waters converting the energy of sunlight into the sugars and carbon bonds of life, producing oxygen and ultimately our atmosphere.
Photosynthesis & Primary Production
Marine algae are the primary producers in the ocean, forming the basis of life on earth. They play a huge role in global photosynthetic oxygen production and are the foundation of marine and terrestrial ecosystems. The primary production of kelp (the production of new biomass by way of internal respiration, detrital material shed, mucus, and other dissolved organic matter) per unit area is amongst the highest known in aquatic ecosystems (NPWS). Marine algae are responsible for nearly 50% of photosynthesis every year.
Listen to a bubble of air produced by algal photosynthesis ping here!
Algal reproduction is diverse across annual, biennial, and perennial species, carried out either by asexual cell division or spores. An appropriate harvest strategy is dependent on localized ecological conditions, timing, and species. The pruning method (small hand-cuts from healthy organisms) generally ensures adequate regeneration in wild harvest contexts. See the Maine Seaweed Council’s Harvester’s Guide to Maine Seaweeds for more detailed guidelines.
Learn more about Bull Kelp's reproductive cycle, alternation and generations, here.
The Intertidal Zone
The shallow, sun-penetrated edges of ocean near land are massive drivers of biological productivity. The intertidal zone, resting between low and high tide marks, is home to vibrant and essential ecosystems at the threshold of the ocean. Seaweed in this zone acts as a wild commons, providing critical habitat for marine life, acting as a nursery for juvenile fish, and transforming sunlight into living carbon in one of the most difficult habitat niches on the planet. Complex and interdependent processes that occur in the intertidal are also vital to coastal human settlements, acting as a carbon sink and tidal barrier (buffer zone), of critical importance, especially when sea level is rising and carbon levels in the atmosphere are at an all time high.
Habitat & Nutrient Source
Kelp forests and other macroalgae beds off the coasts are some of the most dynamic and highly productive ecosystems on earth; they provide foundational marine productivity, yielding three-dimensional habitat for a host of flora, fauna, fish and birds. Kelp bodies provide habitat at multiple levels. The holdfast, stipe, and fronds host marine flora and invertebrates; the surface canopy, mid and bottom areas, and fringe areas support fish; birds make ample use of accumulations of drift kelp for roosting, as well as wrack (kelp detritus washed up on the shore) for food (densities of resident larvae and invertebrates) and organic matter (NPWS). In addition to home-making, kelp act as a direct and indirect food source; in some cases, up to 60% of carbon found in coastal invertebrates is attributable to kelp productivity (NPWS). We can imagine kelp as akin to perennial roots in soil—cycling and sequestering carbon, providing habitat, and producing organic matter--foundational and delightful on many levels.