Nearctic Kelp Beds - Code: Ne12H

From above this habitat is wholly unremarkable. Staring out at the ocean it appears as a large mat of seaweed, just barely disturbing the surface of the water. However, just below the surface lies a towering forest of lush vegetation, teeming with wildlife. Nearctic Kelp Beds are considered one of the most productive environments on the planet and are responsible for 1% of the planet’s primary productivity despite only occupying 0.09% of the Earth’s surface.
Occurring in cold marine waters, this habitat is dominated by large brown algae in the order Laminariales. Brown algae are members of the kingdom Protista which includes organisms like amoeba and slime molds. Despite their unrelated nature, kelps are considered marine analogues to terrestrial plants - where plants have leaves, stems, and reproductive organs, kelp have independently evolved blades, stipes, and sporangia. Kelp beds attach themselves to hard surfaces (usually rocks) with rootlike holdfasts. Gas-filled bladders called pneumatocysts form at the base of blades to help keep blades close to the surface and keep the entire organism vertically stable. Ideal growing conditions for kelp forests include relatively shallow water, high light penetration, high levels of available potassium and nitrogen and a water temperature between 43 and 57 °F (6 and 14 °C ). Under these conditions some species can grow nearly 2 ft (0.5m) per day and reach lengths of 250 ft (80m)!
Most Nearctic Kelp Beds are dominated by a few species that created most of the structure for the wide array of organisms residing in these sheltered environments. On the Pacific coast Giant Kelp (Macrocystis pyrifera) and Bull Kelp (Nereocystis luetkeana) are the two dominant species and this habitat does not exist in the absence of Giant Kelp. Significantly smaller kelp beds occur in the n. Atlantic and are dominated by brown algae in the genus Laminaria.
This habitat is in constant flux and is subject to many forms of disturbance. Annual die-offs occur naturally, especially during the winter months. Primary causes for die-offs include decreased photoperiod, reduced nutrient availability and increased intensity of storms. Nearctic Kelp Beds are also subject to intense predation by marine grazing species which consume the stipes and dislodge/kill kelp. Snails and sea urchins are particularly voracious predators of kelp, in areas where populations of grazers are unnaturally high, large, unvegetated, “urchin barrens” will develop.