Algae forests are underwater areas with a high density of algae growth, usually located offshore at a depth of 10-25 meters. Recognized as one of the most productive dynamic ecosystems on Earth [1] . The largest algae forests are developed in cold seas (the Arctic Ocean , the North Atlantic Ocean , the North Seas), however, in 2007, algae forests were also found in tropical waters near Ecuador [2] . In North America , algae forests are most developed along the Pacific coast , where due to the influence of the cold California currents they are widespread up to the northern tip of the California Peninsula .
In fact, being formed predominantly by brown algae from the order Laminariales , algae forests provide a unique three-dimensional habitat for marine organisms and are a source for understanding many environmental processes.
Content
Algae
Sea forests of algae are formed by various types of algae, depending on the natural zones of their location. So, algae of the genus Macrocystis form similar thickets in Southern California, Nereocystis in Puget Sound , and Laminaria in the cold waters of the far North. In addition to large species, smaller species take part in the formation of this natural zone, which form thickets similar to dense shrubs.
Most often, algal forests are formed by representatives of the genus Macrocystis , although numerous other genera also exist, such as Laminaria , Ecklonia , Lessonia , Alaria, and Eisenia [3] [4] .
All of them grow by attaching rhizoids to rocks or stones at the bottom, in coastal zones, at a depth of 10-25 meters. Algae from the genus Macrocystis are real giants among algae, reaching a length of 60 m, with a mass of up to 150 kg [5] [6] . And their life expectancy can reach 20 years [7] . Thalli of Macrocystis algae grow by about 30-60 cm per day, not much inferior to the growth rate of bamboo. Under favorable conditions and illumination, the species Macrocystis pyrifera can grow up to 25 meters long in just 120 days of continuous growth [8] . At the same time, they form numerous trunks that branch off from the main trunk. One sporophyte can number up to 130 separate “branches”, and in most cases only 30–40 [8] . Reaching the surface, they continue to grow for some time, entangled among themselves, and thereby form a kind of deciduous "field" on the surface of the ocean. The “crowns” thus formed obscure other types of algae, which form a kind of “undergrowth” [7] .
Buoyancy of the thallus is ensured thanks to air-filled bubbles - pneumocysts . In other species, they can be quite large, for example, in representatives of the genera Pelagophycus and Pfereocystis . Pelagophycus has only one pneumocyst, which ends with a smooth trunk at the surface. Its capacity can reach 2.6 liters. The length of the kelp thallus can reach 3-5 m (sometimes 20 m), and the width - up to 0.5 m.
Ecosystem and Biocenosis
The main producers in this ecosystem are not planktonic algae at all, but macrophytes : large attached brown algae . However, these algae are very vulnerable, because sometimes they are actively eaten, especially in the early stages of their development, by various phytophages - sea urchins , mollusks , etc. The main object of competition in these forests of brown algae is sunlight, which ensures the rapid growth of algae. The greatest species diversity of the fauna is observed in the lower tier, at the bottom. Various starfish , sea urchins , bryozoans , crustaceans , crabs , mollusks , and tubular worms abound here. There are also numerous bottom and bottom fish .
The presence of giant brown algae, forming “forests” under water, and “fields” of interlaced parts of thalli on the surface of the water, is one of the necessary conditions for the existence of sea otters .
Notes
- ↑ Mann, KH 1973. Seaweeds: their productivity and strategy for growth. Science 182: 975-981.
- ↑ Graham , MH, BP hi. Kinlan, LD Druehl, LE Garske, and S. Banks. 2007. Deep-water kelp refugia as potential hotspots of tropical marine diversity and productivity. Proceedings of the National Academy of Sciences 104: 16576-16580.
- ↑ Steneck, RS, MH Graham, BJ Bourque, D. Corbett, JM Erlandson, JA Estes and MJ Tegner. 2002. Kelp forest ecosystems: biodiversity, stability, resilience and future. Environmental Conservation 29: 436-459.
- ↑ Jones, CG, JH Lawton and M. Shachak. 1997. Positive and negative effects of organisms as physical ecosystem engineers. Ecology 78: 1946-1957.
- ↑ Abbott & Hollenberg 1976
- ↑ AlgaeBase : Species: Macrocystis integrifolia
- ↑ 1 2 Steneck, RS and MN Dethier. 1994. A functional group approach to the structure of algal-dominated communities. Oikos 69: 476-498.
- ↑ 1 2 Hoek et al. 1995, p. 201
Links
- Underwater forests
- Brown algae forests (inaccessible link)