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Titolo:
Habitat-based assessment of lobster abundance: A case study of an oil spill
Autore:
Cobb, JS; Clancy, M; Wahle, RA;
Indirizzi:
Univ Rhode Isl, Dept Biol Sci, Kingston, RI 02881 USA Univ Rhode Isl Kingston RI USA 02881 ept Biol Sci, Kingston, RI 02881 USA
Titolo Testata:
FISH HABITAT: ESSENTIAL FISH HABITAT AND REHABILITATION
, volume: 22, anno: 1998,
pagine: 285 - 298
SICI:
0892-2284(1998)22:<285:HAOLAA>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMERICAN LOBSTER; HOMARUS-AMERICANUS; DEMOGRAPHIC BOTTLENECK; RECRUITMENT; POPULATIONS; LIMITATION; POSTLARVAL; VARIANCE; FLORIDA; NURSERY;
Tipo documento:
Article
Natura:
Collana
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
41
Recensione:
Indirizzi per estratti:
Indirizzo: Cobb, JS Univ Rhode Isl, Dept Biol Sci, Kingston, RI 02881 USA Univ Rhode Isl Kingston RI USA 02881 Sci, Kingston, RI 02881 USA
Citazione:
J.S. Cobb et al., "Habitat-based assessment of lobster abundance: A case study of an oil spill", AM FISH S S, 22, 1998, pp. 285-298

Abstract

The American lobster Homarus americanus is usually associated with rocky substrate that provides or can be modified into shelter and that may be an essential habitat to early benthic-phase juveniles. The dependence on shelter-providing habitat not only makes possible the definition of essential habitat for lobsters but also permits the assessment of abundance based on theareal extent of habitat. Here, we describe such a habitat-based assessment, performed in response to an oil spill on the coast of Rhode Island, USA. Results from a side-scan sonar survey performed after the spill indicated that the amount of lobster habitat affected by the oil was approximately 9.8km(2) along nearly 15 km of coastline. Postspill lobster density ranged from 0.24 lobsters m(-2) in the impact region to 1.63 lobsters m(-2) in the control region. Qualitative (map contours of lobster density) and quantitative (statistical tests) approaches suggested a significant effect of the spill had been detected by our sampling. An estimate of the total number of lobsters killed was required to scale restoration efforts. We calculated the total number of lobsters in the area by overlaying contours of lobster density on a habitat map generated by side-scan sonar, then multiplying the density of lobsters in each contour interval by the area of appropriate lobster habitat (cobble and boulder) in the contour interval. To calculate loss, we subtracted postspill abundance from prespill abundance. Prespill densitywas estimated to be 1.76 m(-2), which is an adjusted average of airlift samples taken at six Rhode Island sites four months prior to the spill. Calculations of loss based on habitat-specific density estimates were adjusted to reflect undersampling. The loss was estimated to be to be 9.0 infinity 10(6) lobsters. Variability associated with this loss estimate is large; 95% confidence intervals estimated that between 6.7 infinity 10(6) and 15.6 infinity 10(6) lobsters were lost. The calculated loss was very sensitive to changes in prespill density estimates; a change of 0.1 lobsters m(-2) resulted in a change of 0.75-0.9 infinity 10(6) lobsters lost. Habitat-based assessment of lobster population size is possible but requires detailed habitatmaps and accurate density estimates. Natural variability and sampling Limitations give such assessment a wide range of possible values. Nevertheless,the airlift sampling technique, together with side-scan sonar maps of habitat, could provide a powerful tool for estimating the abundance of inshore lobsters.

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Documento generato il 24/09/20 alle ore 08:24:22