|Factors affecting grazer-epiphyte interactions in temperate seagrass meadows|
Jernakoff, P.; Brearley, A.; Nielsen, J. (1996). Factors affecting grazer-epiphyte interactions in temperate seagrass meadows. Oceanogr. Mar. Biol. Ann. Rev. 34: 109-162
In: Oceanography and Marine Biology: An Annual Review. Aberdeen University Press/Allen & Unwin: London. ISSN 0078-3218, more
Epiphytes; Grazing; Sea grass; Temperate zones; Marine
|Authors|| || Top |
- Jernakoff, P.
- Brearley, A.
- Nielsen, J.
This review examines the interactions of grazers and epiphytes in temperate seagrass meadows. These interactions are critical to the dynamic response of seagrass communities that are exposed to a range of internal and external pressures including anthropogenic eutrophication. To predict successfully the outcome of grazer-epiphyte interactions and the resulting impact on the seagrass community, a detailed knowledge of the key processes is required, as well as a knowledge of the magnitude and direction in which they operate. Despite extensive study, the interactions of seagrasses, grazers and epiphytes are poorly known and there have been several reviews on aspects of the research. We extend the scope of previous reviews in a number of areas, particularly with respect to how differences in the life-history patterns of species interact at a variety of spatial and temporal scales. We also review the implications of spatial and temporal variability of grazer-epiphyte interactions to interpretations for studies carried out at a single time or location.The review is in three parts. The first reviews the biology of the main components of seagrass meadows that are relevant to grazer-epiphyte interactions (i.e. seagrasses, epiphytes and grazers). lt examines the range of differences within each of the components that affect the outcome of these interactions (e.g. differences between seagrass species in the size, shape and turnover time of leaves). The second reviews the spatial and temporal scales at which interactions occur. Spatial scales range from within and between seagrass leaves to environmental gradients whereas temporal scales vary from diurnal to annual. The third part reviews how interactions between grazers and epiphytes result in the overall pattern of distribution and abundance. It reviews the implications arising from the scale at which interactions are measured in observational and experimental studies. To predict the impact of grazer-epiphyte interactions, one needs a detailed knowledge of the main processes taking place on several spatial and temporal scales. Furthermore, one cannot simply extrapolate the results of studies from one location or time. The influence of localized conditions, such as the species and morphology of the seagrass, the life history and recruitment patterns of epiphytes and grazers, and the physical environment and its seasonal changes must all be taken into account.Further research on grazer-epiphyte interactions is needed before their role in seagrass communities can be accurately and reliably assessed. We need a better understanding of the recruitment dynamics and dietary preferences of grazers (including assessment of the quality of food), of the local factors likely to affect interactions, and of the likely magnitude of heterogeneity at a range of spatial and temporal scales.