Plant-animal interactions on hard substrata in the north-east Atlantic

• Main Authors: Hawkins, S J, Hartnoll, R G, Kain (Jones), J M, Norton, T A
• Format: Book Part
• Language: English
• Published: Oxford University PressOxford 1992
• Subjects: North East Atlantic
• Online Access: http://dx.doi.org/10.1093/oso/9780198577546.003.0001; https://academic.oup.com/book/chapter-pdf/52423921/isbn-9780198577546-book-part-1.pdf

Abstract The composition of intertidal and subtidal communities within this area is briefly outlined with reference to the British Isles. A major feature is a general trend of decreasing plant dominance and greater numbers of grazers and filter feeders from shelter to wave-exposure in the eulittoral. This pattern changes from north to south, with animal-dominated communities extending further into shelter at more southerly locations. Similarly, southwards, dominance by kelp beds declines low on the shore and in the subtidal, and red algal turfs become more important and grazer diversity increases. The role of plant-animal interactions in energy flow within the mid-intertidal is discussed. Sheltered-shore fucoid beds are net exporters of energy, primarily to the detrital pathway. More exposed shores are net importers of energy, although most in situ microalgal production is consumed within the community. Shores of intermediate exposure are probably modest net exporters. Comparatively little macroalgal production passes through the grazing pathway. The way in which plant-animal interactions structure communities on the environmental gradients of wave-exposure and tidal height/depth in the British Isles is considered. Patella grazing prevents establishment of fucoids on more exposed shores. On moderately exposed shores, escapes offucoids from grazing help to generate patchiness. Within these patchy communities, a complex suite of both positive and negative interactions occurs between plants and animals. On the vertical gradient, grazing is a major structuring agency in the midshore region and just below the kelp canopy in the subtidal. The balance of the interactions is altered by latitude, and grazing becomes less effective further north.