Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 583:137-148 (2017) - DOI: https://doi.org/10.3354/meps12333 Distribution of the isopod Excirolana braziliensis on sandy beaches of the Atlantic and Pacific Oceans Gastón Martínez1,2,*, Matías Arim1,2, Omar Defeo1,2 1Centro Universitario de la Región Este (CURE), Universidad de la República, Ruta 9 y Ruta 15, PC 27000 Rocha, Uruguay 2Departamento de Ecología y Evolución, Facultad de Ciencias, Universidad de la República, PC 11400 Montevideo, Uruguay *Corresponding author: gmartinez@cure.edu.uy ABSTRACT: We assessed geographic patterns of abundance of the isopod Excirolana braziliensis across its whole distribution range in the context of the abundant centre hypothesis (ACH). We also evaluated auxiliary hypotheses to the ACH involving habitat availability and suitability. We compiled species abundance and occurrence information on 139 Pacific and Atlantic sandy beaches of the Americas. Abundance patterns were contrasted against 5 hypothetical distribution models. Habitat availability (sandy beach along the coast), and the role played by grain size on isopod abundance were analysed. Maximum entropy niche modelling based on primary production, salinity, water temperature and tidal range data was used to estimate trends in habitat suitability. E. braziliensis abundance peaked at the 2 edges of its range on the Atlantic coast and towards the centre of its range on the Pacific coast. Congruently, the niche model predicted very low habitat suitability at the centre of the species’ range on the Atlantic coast. Primary production was the main contribution to the model (74.8%). The highest abundances were found in fine sediments (0.20 mm). Support for the ACH for E. braziliensis was found only for the Pacific coast, whereas habitat suitability and availability together with local in-beach morphodynamics accounted for deviations from ACH predictions in the Atlantic. The highest abundances registered in upwelling areas and on beaches with fine sands highlight the primary role played by regional and local conditions over geographic location. KEY WORDS: Abundant-centre hypothesis · Habitat availability · Primary production · Salinity · Sandy beaches · Surface water temperature Full text in pdf format Supplementary materialSee Comment and Reply Comment on this article PreviousNextCite this article as: Martínez G, Arim M, Defeo O (2017) Distribution of the isopod Excirolana braziliensis on sandy beaches of the Atlantic and Pacific Oceans. Mar Ecol Prog Ser 583:137-148. https://doi.org/10.3354/meps12333 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 583. Online publication date: November 16, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.
Highlights
The abundant centre hypothesis (ACH) provides a mechanistic explanation for geographic trends in species abundance (Brown 1984)
These contrasting patterns might be explained by the different geological histories that determine the very dissimilar configuration of Atlantic and Pacific coastlines of the Americas (Kellogg & Mohriak 2001, Mann et al 2007), which in turn defines marked betweenocean differences in habitat availability
Abundance in the Atlantic closely followed trends in habitat availability and suitability and thereby deviated from the pattern predicted by the ACH
Summary
The abundant centre hypothesis (ACH) provides a mechanistic explanation for geographic trends in species abundance (Brown 1984). Among 34 species studied in coastal ecosystems, only 8 showed normal or inverse quadratic models of abundance as predicted by the ACH (Sagarin & Gaines 2002b, Samis & Eckert 2007, Tuya et al 2008, Rivadeneira et al 2010, Fenberg & Rivadeneira 2011, Tam & Scrosati 2011, Baldanzi et al 2013). This contradictory support for the ACH might reflect the occurrence of optimal conditions for peak abundance near species limits (ramped models, 13 species). Discontinuous distributions associated with environmental conditions and species interactions have been reported elsewhere (Sagarin et al 2006)
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