Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa

dc.contributor.advisorBranch, George Men_ZA
dc.contributor.authorDay, Elizabethen_ZA
dc.date.accessioned2014-11-16T20:06:49Z
dc.date.available2014-11-16T20:06:49Z
dc.date.issued1998en_ZA
dc.descriptionBibliography: 172-183.en_ZA
dc.description.abstractField surveys were carried out in the kelp beds of the shallow subtidal off the south western Cape of South Africa, which confirmed the existence of a strong positive relationship between the urchins Parechinus angulosus and juveniles of the abalone Haliotis midae. Both species occupied primarily hard substrates, showing preferences for encrusting corallines. Of the juvenile abalone sampled, > 98% were found beneath sea urchins. All small (3-10 mm shell length) and medium sized (11-20 mm shell length) abalone juveniles occurred under urchins, whether on flat or vertical reef, or in crevices. A small proportion (approximately 10%) of large juveniles (21-35 mm shell length) were not found under urchins, and in these instances all occupied crevices instead. Subsequent surveys also revealed a positive, but weaker, association between abalone recruits (<3 mm shell length) and urchins - an unexpected result, given that abalone recruits are cryptic against the encrusting coralline substrate that they occupy preferentially. Thus camouflaged, they were assumed to gain little additional benefit from sheltering beneath urchins. Selectivity indices showed that, amongst different morphological categories of encrusting corallines, recruits showed preferences for strongly-textured corallines, such as the so-called "knobbly" and "paint" textures. Lower densities of recruits per unit substrate area were recorded on the smoother "velvet" corallines. However, almost all (80%) of recruits were found on velvet corallines occurred under urchins, as opposed to 28 and % of recruits on paint and knobbly corallines respectively.en_ZA
dc.identifier.apacitationDay, E. (1998). <i>Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Biological Sciences. Retrieved from http://hdl.handle.net/11427/9690en_ZA
dc.identifier.chicagocitationDay, Elizabeth. <i>"Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1998. http://hdl.handle.net/11427/9690en_ZA
dc.identifier.citationDay, E. 1998. Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Day, Elizabeth AB - Field surveys were carried out in the kelp beds of the shallow subtidal off the south western Cape of South Africa, which confirmed the existence of a strong positive relationship between the urchins Parechinus angulosus and juveniles of the abalone Haliotis midae. Both species occupied primarily hard substrates, showing preferences for encrusting corallines. Of the juvenile abalone sampled, > 98% were found beneath sea urchins. All small (3-10 mm shell length) and medium sized (11-20 mm shell length) abalone juveniles occurred under urchins, whether on flat or vertical reef, or in crevices. A small proportion (approximately 10%) of large juveniles (21-35 mm shell length) were not found under urchins, and in these instances all occupied crevices instead. Subsequent surveys also revealed a positive, but weaker, association between abalone recruits (<3 mm shell length) and urchins - an unexpected result, given that abalone recruits are cryptic against the encrusting coralline substrate that they occupy preferentially. Thus camouflaged, they were assumed to gain little additional benefit from sheltering beneath urchins. Selectivity indices showed that, amongst different morphological categories of encrusting corallines, recruits showed preferences for strongly-textured corallines, such as the so-called "knobbly" and "paint" textures. Lower densities of recruits per unit substrate area were recorded on the smoother "velvet" corallines. However, almost all (80%) of recruits were found on velvet corallines occurred under urchins, as opposed to 28 and % of recruits on paint and knobbly corallines respectively. DA - 1998 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1998 T1 - Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa TI - Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa UR - http://hdl.handle.net/11427/9690 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9690
dc.identifier.vancouvercitationDay E. Ecological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africa. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Biological Sciences, 1998 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9690en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Biological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherZoologyen_ZA
dc.titleEcological interactions between abalone (Haliotis midae) juveniles and sea urchins (Parechinus angulosus), off the south-west coast of South Africaen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
thesis_sci_1998_day_e (1).pdf
Size:
13.5 MB
Format:
Adobe Portable Document Format
Description:
Collections