Introduction

Study aims

This report has been prepared as a summary of the biological and ecological information available to date (1998) on the kelp beds in European, and more specifically in UK, coastal waters. It is one of a series of nine reviews on coastal marine habitats that have been identified as being of significance in terms of the EU Habitats Directive and which are included in the UK Marine SAC’s Project.

The "kelp forests" have been selected as biotope complexes to be scientifically reviewed for the UK Marine SACs Project for the following reasons:

  • Kelp forests occur in 8 of the proposed demonstration marine SACs within the UK (see linked table)
  • Kelp forests have considerable conservation value because they harbour a very high diversity of organisms, confined to a very narrow fringe along the coastline.
  • The kelp forests throughout Europe are threatened by the effects of several forms of human activity, including harvesting and eutrophication
  • Laminaria hyperborea and Laminaria digitata are regarded as commercially valuable species and demand for exploitation is increasing; this should be counterbalanced by the provision of reserve areas.

What is kelp and why is it important?

Kelp is the colloquial name given to the large, brown seaweeds of the order Laminariales which dominate much of the shallow sublittoral in temperate parts of the world. Kelp plants are physically large, from several metres to several tens of metres tall, and when they are present in dense stands known as "kelp forests" they form an important habitat for other organisms. The kelp forests that are found fringing the temperate sea shores of the world are possibly the most ecologically dynamic and biologically diverse habitats on the planet. These marine forests are the underwater equivalent of the terrestrial rain forests and, just as there are African, Asian and American tropical and temperate rain forests, so in the various oceans of the world are there different species assemblages and ecological linkages in the kelp forests. In north-west Europe the major kelp species is Laminaria hyperborea although others may be locally dominant in particular ecological situations e.g. Laminaria saccharina, Laminaria digitata, Alaria esculenta and Saccorhiza polyschides.

There are many thousands of animal species that live within the kelp forests of the world, either on the rock substratum or on the kelp plants. There are also thousands of different species of seaweeds in these forests, forming layers of plant life in the same way that terrestrial forests have layers of plants (canopy, epiphytes, sub-canopy, understorey, etc.). However, the kelp forests differ from the terrestrial forests in that kelp forests, with their very high productivity, provide the food source for most of the animals in the areas surrounding the kelp forests as well as within them. The material that is continually being lost from the kelp plants feeds into a complex recycling system of herbivores, detritivores, and bacteria, all of which form part of an immense web of interacting species of plants and animals that extend the influence of kelp forests far beyond the habitat of the kelp plants themselves.

In the same way that terrestrial forests supply timber and valuable food species for humanity - and so are threatened to destruction by over exploitation - kelp forests are also under threat. Kelp species themselves are harvested as feedstock for fertiliser and chemical industries and for food, at a present rate (world-wide) of about 2.5 million tons per year. Kelp extracts have a multitude of applications as homogenising and gelling agents (toothpaste, non-drip paint, etc.) and demand for these chemicals is increasing. Other species of algae in kelp beds also have commercial value as human foodstuffs or as a fodder crop in aquaculture (e.g. Dulse, Palmaria palmata in Ireland). Many of the animal species found in kelp forests are also commercially exploited, lobsters, crabs, crayfish, abalone and many fish species are all harvested from kelp beds in different parts of the world.

Definitions

Conservation significance of kelp forests

Kelp distribution in European and UK waters

Kelp beds - the advantages and limitations of the MNCR biotope classifications

References