Laminaria saccharina park on very sheltered lower infralittoral rock
Ecological and functional relationships
Saccharina latissima is the most conspicuous species and dominates the biotope from the point-of-view of ecological relationships. The kelp fronds shade the understory algae and rock below and are likely to sweep the rock - both creating areas where other algae struggle to survive. The sea urchins Echinus esculentus and Psammechinus miliaris graze the rock below leaving, with the effects of frond-sweeping, extensive bare crustose coralline algae dominating the rock. However, large solitary tunicates colonize the rock and the algae, typifying situations of very low water movement where active suspension feeders thrive.
Seasonal and longer term change
Growths of ephemeral algae are likely during the summer together with fresh growth of perennial algal species. Associated fish such as two-spot gobies are likely to be present in higher abundance at the end of the summer than at the start. Seabed animal species in this biotope are not highly changeable.
Habitat structure and complexity
The biotope offers a wide range of surfaces for settlement and shelter of species. The bedrock is colonized by encrusting and foliose red algae with a variety of tubicolous animals and ascidian species attached. The holdfasts of Saccharina latissima
offer refuges for a wide range of small mobile species such as worms and amphipods whilst the fronds may be colonized by encrusting bryozoans, hydroids and ascidians. The shelter afforded by algal fronds attracts small fish species. Complexity is increased if the rock is fissured or the biotope colonizing boulders where the underboulder habitat provides additional shelter and complexity.
Primary and secondary productivity are probably both high. Algae are consumed directly by urchins especially and also provide material for detritus feeders when they die and break-up. Much secondary productivity relies on the acquisition of suspended food by active suspension feeders especially ascidians.
The characterizing species in this biotope all have planktonic larvae and propagules and are mainly short-lived. There is therefore high recruitment and high turnover. However, species that require or prefer settlement on algal substrata will require presence of those substrata.
Time for community to reach maturity
The main characterizing species, Saccharina latissima
, rapidly colonizes cleared areas of the substratum and Kain (1975) recorded that Saccharina latissima
(studied as Laminaria saccharina
) was abundant six months after the substratum was cleared so colonization should be rapid. However, whilst it most likely settles rapidly, the coralline algal species covering rock, represented by Lithophyllum incrustans
, grows at a rate of only <7mm a year (Irvine & Chamberlain 1994) and will take much longer to reach significant cover.
This review can be cited as follows:
Laminaria saccharina park on very sheltered lower infralittoral rock.
Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line].
Plymouth: Marine Biological Association of the United Kingdom.
Available from: <http://www.marlin.ac.uk/habitatecology.php?habitatid=357&code=1997>