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Indicator summary

Summary of indicator structure and function

Definition and/or background

The following is from Fulton et al 2004a -

Detrital dominance is quantified as the proportion of total flows that originate from detritus. This model-derived indicator measures the importance of detritus for the flows in an ecosystem and is also thought to be a measure of system maturity. It has been proposed that as a system matures it moves from being dominated by herbivory to being dominated by detritivory (Odum 1969). However, it is possible that degradation of system via increased deposition of detrital matter (e.g. from discards) could also shift a system to detritivory without enhancing system maturity. Nevertheless, for better or worse, by tracking the value of detrital dominance through time, or by comparing the value at fished and unfished sites, it may be possible to detect changes in systems that are due to fishing.

Attribute

Ecosystem structure and function, Community structure, Eutrophication

Purpose

Fisheries

Data required

The following is from Fulton et al 2004a -

• Biomass per species (or group) recorded (preferably at least for the main components of the ecosystem and through time or vs. some reference area)
• Taxonomic data (or at least categorisation of the main components of the system)
• Catch data of species in fishery
• Mortality estimates for each group
• Consumption / Biomass estimates for each group
• Diet data

Ecosystem applicability

The following is from Fulton et al 2004a -

Should be applicable in all ecosystems.

Robustness

The following is from Fulton et al 2004a -

Medium to low: this indicator is easily confounded by other factors that influence detritus. However, it may prove to be a strong indicator of the effects of fishing in systems where fisheries discard large amounts of organic material, or where fisheries simplify the trophic web to such an extent that the importance of herbivory increases substantially. As a model-derived indicator it is reliant on the assumptions used to construct the underlying model and the data used to parameterise and initialise the model. This makes it unsuitable as a predictive indicator, but this does not prevent it from being an informative indicator, especially if it is part of a larger suite of indicators.

References

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:

Odum, E. P. 1969. The strategy of ecosystem development. Science 164, no. 18 April: pp 262-70.

Background reading

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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