Recreational impact versus public enjoyment

Monitoring programmes.

Recovery

Recreational impact versus public enjoyment.

In the above sections we have highlighted the value of rocky shores as a public amenity for recreation and education, and the damage that visitors can cause. Educational field trips may increase this impact through samples collection and localised trampling. Easy public access lends conservation value to rocky shores. Ways should be found to minimise disturbance without unduly restricting such access, especially in SACs. Increasing public awareness may significantly reduce impacts of visitors, through promotion of positive behaviour (Chan, 1970). Hawkins and Jones (1992) list guidelines to minimise damage inflicted during field trips. A programme of public education could involve signs explaining the conservation significance of the site or a visitor centre (Fletcher, 1997), which may result in increased support for the SAC. It may also be necessary to encourage the public to limit their use of the shore to designated areas. Some site-specific research into the effects of visitors may be necessary.

Rocky shores are generally accessible, can be surveyed rapidly and are well understood. Techniques involve low-cost equipment and give the potential for rapid collection of quantitative or semi-quantitative data. Site visits are, however, time-consuming and necessarily limited to the daytime low tide periods of just a few hours each day. Consequently the choice of sites and the data collected need to be made maximally effective. We believe that this can be best achieved by careful consideration of the design of the survey in relation to the question asked, with a statistical hypothesis-testing rationale as the main underpinning for the adopted scheme. Estimation of abundance or cover estimates should be made for the main space-occupying (algae, barnacles, mussels), abundant structuring organisms (grazers, predators), and other species identified as important indicators of community type and environmental impacts. It matters less that abundance or cover data is collected in a rapid semi-quantitative way than that the sites and stations at which data are collected are chosen effectively. Assignment of a shore community to a biotope should not necessarily be the final aim of shore surveys, despite the attractiveness of the concept from a management viewpoint.

Long term studies following the Torrey Canyon oil spill demonstrate that rocky shore communities can recover. The length of time this takes depends on the scale of the disturbance. The extent of any recovery should be assessed by reference to baseline data wherever possible.

In many cases, shore communities will recover best without human intervention and any post-impact management will often consist of monitoring this recovery. Some exceptions in which additional measures may aid recovery are discussed below. The Torrey Canyon incident illustrates that attempts to intervene can backfire. The consequences of any measures should be carefully assessed before they are widely used.

If the shore is badly affected by litter or debris, the only solution is physical removal of the offending material. Mechanical methods should be avoided as these may cause physical disturbance to the biological community. Removal by hand is labour intensive but often effective. The Marine Conservation Society successfully organises beach clean ups using a volunteer workforce.

Communities may never naturally recover from invasion by an introduced species. The extent of the impact of a species on biodiversity will depend on several factors. Measures to control the spread of particularly damaging species might be the only way to conserve threatened communities. Many chemical and biological methods have been used in attempts to control ‘pest’ species. These control methods have had varying degrees of success and often cause severe ecological consequences. The development of safe and effective methods of control needs further research.

Some rocky shore species, such as dogwhelks, do not have a planktonic dispersal phase and are slow to recolonize sites after disturbance. Recolonization may occur only after adult individuals are transported to the shore by floating debris, for example. Reintroductions may be attempted from nearby populations to speed up the natural process. Some considerations need to be addressed before mass transplantation. Populations of such species are often adapted to their home shore. Dogwhelks from an exposed shore have low shells with large apertures which help them to withstand wave action but make them vulnerable to predation by crabs which are more numerous on sheltered shores. The ability of a population to survive in a particular area depends on the existing community in that area, not least its prey species.

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