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Using historical data to detect temporal changes in the abundances of intertidal species on Irish shores

journal contribution
posted on 2023-05-17, 06:33 authored by Simkanin, C, Power, A, Myers, A, McGrath, D, Southward, A, Mieszkowska, N, Leaper, R, O'Riordan, R
An historical data set, collected in 1958 by Southward and Crisp, was used as a baseline for detecting change in the abundances of species in the rocky intertidal of Ireland. In 2003, the abundances of each of 27 species was assessed using the same methodologies (ACFOR [which stands for the categories: abundant, common, frequent, occasional and rare] abundance scales) at 63 shores examined in the historical study. Comparison of the ACFOR data over a 45-year period, between the historical survey and re-survey,showed statistically signi¢cant changes in the abundances of 12 of the 27 species examined. Two species(one classed as northern and one introduced) increased signi¢cantly in abundance while ten species (¢ve classed as northern, one classed as southern and four broadly distributed) decreased in abundance. The possible reasons for the changes in species abundances were assessed not only in the context of anthropogenic e¡ects, such as climate change and commercial exploitation, but also of operator error. The error or di¡erences recorded among operators (i.e. research scientists) when assessing species abundance using ACFOR categories was quanti¢ed on four shores. Signi¢cant change detected in three of the 12 species fell within the margin of operator error. This e¡ect of operator may have also contributed to the results of no change in the other 15 species between the two census periods. It was not possible to determine the e¡ect of operator on our results, which can increase the occurrence of a false positive (Type 1) or of a false negative (Type 2) outcome.

History

Publication title

Marine Biological Association of The United Kingdom. Journal

Volume

85

Issue

2005

Pagination

1329-1340

ISSN

0025-3154

Department/School

Institute for Marine and Antarctic Studies

Publisher

Cambridge Univ Press

Place of publication

40 West 20Th St, New York, USA, Ny, 10011-4211

Rights statement

Copyright © 2005 Cambridge University Press

Repository Status

  • Restricted

Socio-economic Objectives

Climate change adaptation measures (excl. ecosystem)

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