Indicator | Attribute | Purpose | If restricted to taxa, list which ones | Ecosystem applicability | Identified capability | Biological classification level | Response variable | Drivers | Robustness |
|---|---|---|---|---|---|---|---|---|---|
Redfield ratio | Trophic structure, Eutrophication |
|
| Should be applicable in all ecosystems | Demonstrable | Ecosystem | Environmental | Environmental, Anthropogenic | Low to medium |
The following is from Fulton et al 2004a -
It has been demonstrated that synchronous anthropogenic impacts (e.g. of run-off from the land combined with benthic disturbance by fishing operations) can upset the ratio of nitrogen, phosphorous and carbon required for maintaining balanced systems. This is particularly true for semi-enclosed marine systems, estuaries, inshore coastal areas close to population or agricultural centres (Caddy 2000). Redfield’s Ratio is a potential indicator for measuring trends in these nutrients. It is based on the concept, described by Redfield in 1934, that different biogeochemical cycles are linked through mass balance of different elements. Redfield found that many samples of plankton had an average C:N:P ratio of 106:16:1. The ratio has since been explored for many marine taxa. More recently it has been found that Redfield’s ratio has potential as an indicator for interpreting changes in nutrient cycling. For example, deviations of the Redfield ratio from 16:1 for N:P levels can be used to infer nutrient limitation in a particular environment (Hammond and Synnot 1994). This is based on the fact that marine systems are largely constrained by low nutrient levels, with nitrogen and occasionally phosphorous (or silicon) limiting primary production (Caddy 2000)
Trophic structure, Eutrophication
The following is from Fulton et al 2004a -
N, P and C levels for the system under examination or species investigated
The following is from Fulton et al 2004a -
Should be applicable to all systems, though the ratio is likely to be different in oligotrophic conditions, due to the preferential recycling of nitrogen and phosphorous in comparison with carbon.
The following is from Fulton et al 2004a -
Low to medium: While a sensitive indicator of nutrient conditions it is not only indicative of the impacts of fishing. Other anthropogenic activities can impact upon this indicator (e.g. pollution). Moreover, the ratio will differ slightly depending on whether the system is oligotrophic, mesotrophic or eutrophic so reference points or background research in appropriate nutrient conditions is necessary.
Fulton, E.A., Smith, A.D.M., Webb, H., and Slater, J. (2004a) Ecological indicators for the impacts of fishing on non-target species, communities and ecosystems: Review of potential indicators. AFMA Final Research Report, report Number R99/1546.
References that Fulton et al uses for this indicator:
Caddy, J. F. 2000. Marine catchment basin effects versus impacts of fisheries on semi-enclosed seas. ICES Journal of Marine Science 57: pp 628-40.
Fulton, E.A., Fuller,M., Smith, A.D.M., and Punt, A. (2004) Ecological indicators of the ecosystem effects of fishing: Final report. AFMA Final Research Report, report Number R99/1546.
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