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Chown S.L.,Monash University | Haupt T.M.,Stellenbosch University | Haupt T.M.,Marine Biodiversity and Ecosystem Research | Sinclair B.J.,University of Western Ontario
Journal of Insect Physiology | Year: 2016

Temperature compensation in whole-animal metabolic rate is one of the responses thought, controversially, to characterize insects from low temperature environments. Temperature compensation may either involve a change in absolute values of metabolic rates or a change in the slope of the metabolic rate - temperature relationship. Moreover, assessments of compensation may be complicated by animal responses to fluctuating temperatures. Here we examined whole animal metabolic rates, at 0°C, 5°C, 10°C and 15°C, in caterpillars of the sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae), following one week acclimations to 5°C, 10°C and 15°C, and fluctuating temperatures of 0-10°C, 5-15°C, and 10-20°C. Over the short term, temperature compensation was found following acclimation to 5°C, but the effect size was small (3-14%). By comparison with caterpillars of 13 other lepidopteran species, no effect of temperature compensation was present, with the relationship between metabolic rate and temperature having a Q10 of 2 among species, and no effect of latitude on temperature-corrected metabolic rate. Fluctuating temperature acclimations for the most part had little effect compared with constant temperatures of the same mean value. Nonetheless, fluctuating temperatures of 5-15°C resulted in lower metabolic rates at all test temperatures compared with constant 10°C acclimation, in keeping with expectations from the literature. Absence of significant responses, or those of large effect, in metabolic rates in response to acclimation, may be a consequence of the unpredictable temperature variation over the short-term on sub-Antarctic Marion Island, to which P. marioni is endemic. © 2015 Elsevier Ltd. Source

Haupt T.M.,Stellenbosch University | Haupt T.M.,Marine Biodiversity and Ecosystem Research | Sinclair B.J.,University of Western Ontario | Shaw J.D.,University of Queensland | And 2 more authors.
Antarctic Science | Year: 2015

On sub-Antarctic Marion Island, wandering albatross (Diomedea exulans) nests support high abundances of tineid moth, Pringleophaga marioni, caterpillars. Previous work proposed that the birds serve as thermal ecosystem engineers by elevating nest temperatures relative to ambient, thereby promoting growth and survival of the caterpillars. However, only 17 days of temperature data were presented previously, despite year-long nest occupation by birds. Previous sampling was also restricted to old and recently failed nests, though nests from which chicks have recently fledged are key to understanding how the engineering effect is realized. Here we build on previous work by providing nest temperature data for a full year and by sampling all three nest types. For the full duration of nest occupancy, temperatures within occupied nests are significantly higher, consistently by c. 7°C, than those in surrounding soils and abandoned nests, declining noticeably when chicks fledge. Caterpillar abundance is significantly higher in new nests compared to nests from which chicks have fledged, which in turn have higher caterpillar abundances than old nests. Combined with recent information on the life history of P. marioni, our data suggest that caterpillars are incidentally added to the nests during nest construction, and subsequently benefit from an engineering effect. © 2015 Antarctic Science Ltd. Source

Samaai T.,Marine Biodiversity and Ecosystem Research | Samaai T.,University of Cape Town | Janson L.,Marine Biodiversity and Ecosystem Research | Kelly M.,NIWA - National Institute of Water and Atmospheric Research
Zootaxa | Year: 2012

Three new species of Latrunculia are described from Algoa Bay, and Alphard and 45-Mile Banks, on the Agulhas continental shelf off the southern coast of South Africa. Latrunculia gotzi sp. nov., from Alphard Banks, forms a thick raised pad with broad, low, meandering areolate porefields that are characteristically lighter in colour than the surrounding mahogany brown ectosome. Latrunculia kerwathi sp. nov., from 45-Mile Banks, forms a thin, dark greenish brown encrustation, with very small, discrete, crater-shaped porefields. Latrunculia algoaensis sp. nov., from Algoa Bay, is a green hemisphere with relatively large, thick-lipped, circular areolate porefields. While the megascleres in these new species vary specifically in their dimensions, the former two species have small irregular spines on the styles. The anisodiscorhabds of the new species also vary specifically in dimensions and degree of ornamentation, but have an undifferentiated basal whorl and manubrium, with only median and subsidiary whorls around the shaft. These are identical in overall form to the anisodiscorhabds in several South African and New Zealand species currently recognised within the subgenus Latrunculia (Biannulata) Samaai et al., 2006, a group of 13 species for which no type species was ever assigned. A type species is designated herein. © 2012 Magnolia Press. Source

Gotz A.,South African Environmental Observation Network | Gotz A.,Rhodes University | Gotz A.,Nelson Mandela Metropolitan University | Kerwath S.E.,Fisheries Research | And 6 more authors.
African Zoology | Year: 2014

Despite their ecological and economic importance, the temperate reef habitats of the central Agulhas Bank remain poorly studied. From 2008 to 2010, multiple stations grouped into six general sites of varying depth, profile and distance offshore, were surveyed. A combination of linefishing and fishtrapping was found to be most suitable to assess the ichthyofauna. The survey yielded a total catch of 8470 individuals (45 species) from 183 stations from a depth range between eight and 100 metres. Multivariate analyses indicated that the demersal reef fish community of the central Agulhas Bank is determined by depth rather than distance offshore, and that offshore reefs can function as fish aggregating structures for some of the region's overexploited species such as carpenter (Argyrozona argyrozona). . Source

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