Defining the Ecosystem
Macfadyen (1963), provided the first comprehensive review of the evolving concept of the ecosystem. Drawing together reviews from Balogh (1957), Thienemann (1926) and Friedrichs (1927) Macfadyen states that the relationship between the biozönose of Mobius (1877) and the biotope of Dahl (1908) are reciprocal. In other words, not only is a characteristic community of organisms associated with and dependent on a characteristic habitat, but also the habitat is modified and to a greated or lesser extent created by the activities of the organisms found there. These two components evolve together in such a way as to develop into a single system. It is to this system that Tansley (1935) gave the term "ecosystem".
It follows from this that any change to the communities inhabiting the ecosystem or changes to the physical environment impact on each other, and so the logical approach to environmental management would be to manage the ecosystem as a unified entity. However it wasnt until 1992 that this was recognised. At the Earth Summit in Rio de Janeiro, it was acknowledged that the traditional sectoral approach to natural resource and environmental management was insufficiently addressing the human impacts (and the relevance to ECASA - the impacts of aquaculture), on the environment. There was a need to take a holistic ecosystem approach to environmental management. This ecosystem approach was seen as the key to delivering sustainable development.
Ecosystems, for the purposes of environmental management, may be considered as subdivisions of the Earths surface and lower atmosphere within which natural processes operate and biological communities perpetuate themsleves. Often they do not have readily identifiable boundaries because many of their intrinsic processes, (e.g. supply of nutrients), originate beyond any obvious habitat or structural limits and operate at a range of scales. This is the challenge for ECASA.
In contrast to more readily definable ecosystems (e.g. a forest or enclosed lake), the character of the sea appears relatively seamless with ecological processes operating over a range of scales and distances. Boundaries can be subtle and may be defined by temperature, currents, depth stratification and salinity. In practice the scale of the marine ecosystems most appropriate for the application of the ecosystem approach are those relating to a particular human activity. Providing the tools and methods to do this has been the underlying purpose of ECASA, and this Toolbox.
You may be interested in looking at other information in this section;
The science behind ECASA - if you are interested in the methods used by ECASA to make and test the tools in the Toolbox
About the definitions of scales - read this to understand the difference between farm scale, water body scale and regional scale.
References.
Balogh, J. (1958). Lebensgemeinschaften der Landtiere, (Budapest)
Dahl, F., (19080. Die Lycosiden oder Wolfspinnen Deutschlands und ihre stellung im Haushalte der Natur. Nova Acta. Leop. Carol. Dtsch. Akad. Naturforsch. Vol. 88, 174-678.
Friedrichs, K. (1927). Grundsätzliches über die Lebenseinheiten höher Ordnung und den Ökologischen Einheitsfaktor. Naturwissenschaften. Vol. 15, 5770579.
Macfadyen, A. (1963). Animal Ecology. Second edition. Pitman Publishing, London.
Möbius, K., (1877). Die Auster und die Austerwirtschaft. (Berlin).
Tansley, A. G., (1935). The use and abuse of vegetational concepts and terms. Ecology. Vol. 16, 284-307.
Thienemann, A. (1926). Die Nährungskreislauf im Wasser. Verh. dtsch.zool.Ges. Vol. 31, 29-79.
