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Indicator summary

Summary of indicator structure and function

Definition and/or background

The following is from Fulton et al 2004a -

In an “unstressed ecosystem”, successional stages in a marine community should be reflected by the majority of habitats being in more mature stages. Where there are a high proportion of sites, in a given bioregion, under early successional states (e.g. urchin barrens where there should be kelp forests) it indicates disturbance (by fishing, or invasion of exotic species, or pollution). A way of measuring the successional status of sites within a marine bioregion or ecosystem would be useful in order to track changes over time and relate the changes to agents of disturbance, such as fishing. Done and Reichelt (1998) have developed an indicator for measuring and tracking the status and successional stage of coral reef habitats. The rationale for this index is that habitats subject to varying levels of fishing will be at particular successional stages.

Bioconstruction Index

The index is the sum of the percentage of sessile biota weighted by the estimated ages of the biota and is calculated using the following relationship:

where a_i is age class i (in years) and m_i is theproportion of defined area covered by individuals of age i. For example, an area 100% covered by 1000-yr old organisms would score 1000, whereas a 100% cover of 1-yr old organisms would score 1. Results can be simply graphed to provide a conceptual view of the status of an ecosystem.

Attribute

Community composition, Habitat structure and condition

Purpose

Fisheries

Taxa

Data required

The following is from Fulton et al 2004a -

• Area (km2) of sites
• % cover of sessile biota (may be species specific or aggregated across species)
• Estimated age of sessile biota (may be species specific or aggregated across species)

Ecosystem applicability

The following is from Fulton et al 2004a -

The bioconstruction index was developed for coral reefs but could be applied to other benthic habitats, particularly ones based on hard substrata.

Robustness

The following is from Fulton et al 2004a -

Low, may increase with testing: Limitations are that without ecological data on when different successional states are symptomatic of anthropogenic degradation or natural disturbance it would be hard to interpret. Thus, the uncertainty lies with determining which states are natural and which are human induced. However, since there have been a few major detailed studies into effects of trawling on benthic habitats (e.g. Northern Prawn Trawl Fishery of Northern Australia, Poiner et al. 1998; Grand Banks of Newfoundland, Prena et al. 1999; Gulf of Alaska, Freese et al.1999; Gulf of Maine, Auster et al. 2001; Scotland, Tuck et al.1998), data from these studies could be tested with this index to measure it’s robustness.

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:

Done, T. J., and R. E. Reichelt. 1998. Integrated coastal zone and fisheries ecosystem managment: generic goals and performance indices. Ecological Applications 8, no. 1, Supplement: pp S110-S118.

Freese, L., P. J. Auster, J. Heifetz, and B. L. Wing. 1999. Effects of trawling on seafloor habitat and associated invertebrate taxa in the Gulf of Alaska. Marine Ecology Progress Series 182: 119-26.

Poiner, I. R., J. Glaister, C. R. Pitcher, C. Burridge, T. Wassenberg, N. Gribble, B. Hill, S. J. M. Blaber, D. Milton, D. Brewer, and N. Ellis. 1998. "Final report on effects of trawling in the far northern section of Great Barrier Reef: 1991-1996. Vol.1: chapters 1 to 3 ." CSIRO Div. of Marine Research, Cleveland, Qld..

Prena, J., P. Schwinghamer, T. W. Rowell, D. C. Jr. Gordon, K. D. Gilkinson, W. P. Vass, and D. L. McKeown. 1999. Experimental otter trawling on a sandy bottom ecosystem of the Grand Banks of Newfoundland: analysis of trawl bycatch and effects on epifauna. Marine Ecology Progress Series 181: pp 107-24.

Tuck, I. D., S. J. Hall, M. R. Roberston, E. Armstrong, and D. J. Basford. 1998. Effects of physical trawling disturbance in a previously unfished sheltered Scottish sea loch. Marine Ecology Progress Series 162: pp 227-42.

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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