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This study investigated the factors that maintain the patchiness of various rocky shore communities, particularly the roles of physical disturbance and biological interactions. Three communities were studied: a rnidshore red algal turf dominated by Laurencia pinnatifida, a Cladophora rupestris turf that dominated an area of the lowshore'and a fucoidbarnacle mosaic in the rnidshore that was interspersed by limpets. The study of the Laurencia turf showed it to be extremely stable once established and that its primary mode of recolonisation was by vegetative encroachment. Because of its slow growth L. pinnatifida did not recolonise and dominate any gaps that occurred in the turf within the timescale of this study. The Cladophora rupestris community was not only extremely stable, but was also persistent. Cladophora rupestris returned as the dominant alga to disturbed areas irrespective of the size, shape or season of the disturbance and this may have been because of processes involving the inhibition of other species such as Fucus serratus by early successional species which Cladophora rupestris could tolerate. Repeated disturbance events may have broken such inhibitions, enabling other species to colonise the substratum to higher levels of abundance than would normally have occurred. In the Laurencia and Cladophora turfs few limpets were required to maintain gaps in the turf, but these areas were rapidly recolonised by algae if all limpets were removed. The gaps in the Cladophora turf became dominated by Cladophora rupestris, however, in the Laurencia turf Laurencia pinnatifida did not recolonise the gaps that had been kept clear by limpet grazing. In the midshore fucoid, barnacle and limpet community the limpet densities had to be reduced to half of the natural levels to permit the colonisation of barnacle matrix by algae. The cover by FUCllS vesiculosus was .inversely related to the density of limpets, with the largest values being obtained in areas that were devoid of limpets. The effect of modifying the environmental conditions, by shading and watering the barnacle matrix, on the establishment of Fucus vesiculosus germlings was also studied. This showed that more shade tended to result in a greater number of fucoid escapes, possibly because of insolation stress and photoinhibition of the germlings on the unshaded substratum. The persistence offucoid patches was found to be affected by both the size of the area and the duration for which it was protected from limpet grazing. From the studies I carried out it is apparent that there were several forms of patchiness on the moderately exposed rocky shores on the south coast of the Isle of Man. These result from the vertical environmental stress gradient and interactions between plants and animals and in each case the exact sequence of events that followed a disturbance, depended on the species involved.

This study investigated the main and interactive effects of nearshore breakwaters and marsh vegetation on faunal abundance and diversity along an eroded shoreline in Bon Secour Bay, Alabama. In summer 2016, eight replicates of three vegetation treatments plots (naturally vegetated, planted, and open) were established along a breakwater-protected and an adjacent no breakwater shoreline. After which, three methods were used to evaluate nekton quarterly from summer 2016 to summer 2018; Breder traps along the shoreline and lift nets and trawls in nearshore waters. Data were analyzed using the Shannon-Weiner diversity index and ANOVA. Results showed breakwaters supported significantly more abundant and diverse communities along the shoreline and in parallel nearshore waters than similar no breakwater sites. However, the main vegetation treatment effects were not significant. These findings suggest that living shoreline projects with nearshore breakwater support can be beneficial for fisheries enhancement in high-wave energy environments.