Biology and Ecological Functioning

Biological Characteristics

The biology of kelp species has been well researched but the ecological role of kelp species and the interactions between the kelp beds and the surrounding ecosystems are not at all well known, either in Europe or in the world as a whole. A few long-term research programmes have been undertaken in areas where the health of the kelp based communities has major economic importance (e.g. for the crayfish, lobster and abalone fisheries of the NE Pacific, South Africa and W. Australia). There have also been research programmes where kelp is harvested on a large scale, but these have concentrated on the kelp plants themselves rather than on the ecosystem in which they grow. A comprehensive understanding of the biology and ecology of kelp species, the other species of flora and fauna and the dynamics of the kelp biotopes is essential in order that efficient management plans and monitoring programmes can be designed for their conservation.

At present our information on the biology and ecology of the majority of species in the UK kelp beds is such that our understanding of their functioning and ecological interactions is extremely limited, even the basic biological parameters of many of the species are unknown. Despite large numbers of sites having been surveyed, the species that are of key importance to the maintenance of kelp biotopes have not been firmly identified. Because of this, any management and monitoring plans for kelp biotopes will need to be broadly based and encompass all aspects with potential for change in case that change turns out to be crucial to the well being of the protected ecosystem. If an intensive, encompassing and co-ordinated research programme is undertaken in the UK, over time the management and monitoring plans for marine SACs may be refined and targeted at specific threats to species identified as key to the maintenance of the ecosystem.

This section will summarise information on the biology and ecology of the kelp species at present reported from UK waters. In terms of the biomass present in UK kelp beds, the most common kelp species are Laminaria hyperborea, L. digitata, L. saccharina and Saccorhiza polyschides, and information on these species will form the bulk of this section. Where appropriate, information on other kelp species or associated species found in the UK will be included.

Biological Characteristics

The kelp species found around the coasts of the UK are all large brown seaweeds composed of a holdfast attachment to the substratum, a stipe and a blade. There are three separate genera - Laminaria, Alaria and Sacchorhiza.

The large blades of kelps form the most conspicuous component of the sublittoral environment. Blades may be simple and ribbon shaped (with or without a conspicuous midrib) or broad and digitate, although the blades of species that are usually digitate can be undivided under some environmental conditions. Individual plants are perennial but life spans vary with species and environmental conditions, from just about 1 year to nearly 20 years. The stipes are usually round in cross section and may be stiff or flexible, but they are tough and do not snap easily. The holdfasts consist of numerous haptera (root-like outgrowths at the base of the stipe) which adhere firmly to the substratum and anchor the plant. All kelp species grow from meristematic tissue at the base of the blade and, if this region of the blade is lost, the plant cannot grow, and the stipe and holdfast decay and are lost.

Life history and reproduction

Growth

Diversity of habitats, conditions and species

Community structure within kelp biotopes

Keystone and associated species

Nursery areas

Flora and fauna interactions

Biodiversity aspects

References