The morphology of kelp plants makes them relatively easy to study in the field because the individual plants are large and easy to count, and because the basal meristem permits the growth of plants to be measured in situ by following the movement of punched holes away from the base of the blade. Consequently, kelps have probably received more scientific attention than any other group of seaweeds, and the habitats dominated by them have also been fairly well. Nevertheless, there are significant gaps in our knowledge of the ecology of even the commonest kelp species, and much larger gaps in the information available about the animal and plant species that are associated with kelps in kelp forests.

• It is still not possible to define which of these associated species are really diagnostic of, or endemic to, kelp ecosystems, as opposed to those which are favoured by the physical, chemical or biological conditions that a kelp forest creates.

Clearly, the kelp species, themselves, are diagnostic of kelp biotopes, and they would certainly be selected for inclusion in an ‘ACE’ survey (Abundance scale, Check list and Exact location; Hiscock, 1998a) as ‘important’ or conspicuous species, as ‘keystone’ species, as ‘indicator’ species and, possibly, also as ‘sensitive’ species, in view of their susceptibility to human impact. However, in spite of the wealth of information about the ecology of kelp species, it is not easy to select one or two attributes of kelp plants (e.g. density of plants per unit area, stipe dimensions, blade dimensions, growth rate of blades) that could be easily measured in the field and used as an indicator of the health of a kelp forest or ecosystem.

It is also possible that some of the floral and faunal species associated with the blades, the stipes or the holdfasts of the plants, or the substratum or water within the kelp forest, could provide an indication of impending changes in the forest before the large, perennial kelp plants, themselves, begin to react. However, our knowledge of these associated species has barely got beyond the descriptive phase, and we are not yet in a position to say which species should be targeted as potentially sensitive indicators of change.

• The identification of the keystone species in kelp biotopes should receive the highest priority.

Much of the basic research on kelp biotopes that has been undertaken so far, particularly in Europe, has not been directed to the management of these biotopes in their entirety although, as discussed in Chapter V, some recent work has sought to examine the effects of harvesting the kelp on the subsequent recovery of the kelp and its associated species.

In view of the global paucity of management-directed studies on kelp beds, it is difficult to answer even the simplest of management questions. Monitoring options suggested here can, therefore, be based on little more than informed speculation. Firm recommendations could be offered only when the agencies responsible for managing kelp biotopes had reached decisions, based on biological and environmental evidence or legal obligations imposed by statutory bodies, about precisely what is to be monitored and why it should be monitored.

Given adequate background and species specific information, scientists will be able to develop optimal methods for the provision of reliable, reproducible, accurate and relevant data to contribute to the management of the biotope. Conservation and management agencies should make full use of CASE (or CAST in Northern Ireland) research studentships as a cost-effective way of tackling specific management issues in co-operation with marine biologists based in universities.

• The precautionary principle should be adopted until such time as dependable, scientific methods for monitoring and surveilling all necessary aspects of the ecology of kelp biotopes have been developed.

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