Ecological dominance along rocky shores, with a focus on intertidal ascidians
- Authors: Rius, Marc , Teske, Peter R , Manriquez, Patricio H , Suarez-Jimenez, Rocio , McQuaid, Christopher D
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453416 , vital:75252 , ISBN 9781138197862 , https://www.taylorfrancis.com/chapters/oa-edit/10.1201/b21944-4/ecological-dominance-along-rocky-shores-focus-intertidal-ascidians-marc-rius-peter-teske-patricio-manr%C3%ADquez-roc%C3%ADo-su%C3%A1rez-jim%C3%A9nez-christopher-mcquaid-juan-carlos-castilla?context=ubxandrefId=e4c0e0f7-2c0a-417f-8751-8225febf1536
- Description: The role of dominant species is of central importance in ecology. Such species play a key role in ecosystem structure, stability and function, regulating resource allocation across trophic levels and overall ecosystem productivity. Although ecological interactions between dominant and subordinate species are often considered to influence the latter negatively, the presence of dominant species can also be beneficial. These species commonly act as ecosystem engineers and enhance biodiversity by creating habitat for other species. Along rocky coastlines, dominant species are often sessile suspension-feeding organisms that can monopolize all available substrata. This is particularly noticeable in intertidal and shallow subtidal habitats where the number of species that achieve ecological dominance is limited. Here, we review the ecological and evolutionary mechanisms that facilitate dominance along rocky coastlines. We then focus on a prominent example, the members of the Pyura stolonifera species complex (Tunicata), which are an emerging model system for studying ecological dominance. These ascidians achieve the highest biomass levels ever reported in rocky intertidal habitats and, when invasive, can fundamentally transform entire ecosystems. Finally, we discuss conservation implications and conclude with directions for future research.
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- Date Issued: 2017
The relationship between human exploitation pressure and condition of mussel populations along the south coast of South Africa
- Authors: Rius, Marc , Kaehler, Sven , McQuaid, Christopher D
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6913 , http://hdl.handle.net/10962/d1011876
- Description: Human exploitation of intertidal organisms in South Africa is an ancient activity based principally on mussels. We studied mussel populations and patterns of exploitation along a 160-km stretch of the south coast. Photographs (100 per site) were taken of the intertidal rocks at each of 14 sites, covering a range of exploitation intensities. Percentage cover was negatively correlated with number of mussel patches and positively correlated with mean shell width. PCA analysis identified groups of sites: a) accessible and unprotected sites: low cover, small mussels, patchy distribution; b) inaccessible sites and sites next to, or within, nature reserves: high percentage cover, large animals, less patchy distributions. Affluent coastal settlements also seem to confer protection against harvesting. Harvester distribution was examined by aerial surveys and combined with information on distance to the nearest beach access point and number of households within 7 km for each site. Sites within reserves and inaccessible sites had low densities of collectors, whereas sites near urban areas and in the Ciskei had the highest densities. All correlations between indicators of human exploitation and condition of mussel populations were non-significant. However, number of collectors showed positive trends with number of patches and negative trends for the two other variables. The results indicate much lower levels of exploitation than in the neighouring Transkei region, and suggest a high degree of background variability in mussel population structure.
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- Date Issued: 2006