Investigations were carried out into aspects of the bio!ogy and ecology of Helcion pectunculus along the coait of South Africa. These included studies of the distribution, density and biomass of the limpet at six sites along the east coast plus one site on the west coast; the growth of H pectunculus on both west and east coasts; a comparison of the reproductive biology of the east and west coast populations; the foraging activity and feeding behaviour of H pectunculus and the driving forces behind the rhythmic behaviour of this limpet; the importance of the crevice environment in the biology and ecology of H pectunculus. Helcion pectunculus has a restricted zonation, with the majority of animals residing in crevices in the upper Balanoid zone during diurnallowtides, although individuals were occasionally found in the lower Balanoid zone on shores with a gently sloping aspect. This limpet occurs in higher densities (50-lO0 individuals/m2) on shores which have large numbers of crevices and boulders i.e. quartzitic sandstone shores. On most shores, the ratio of males to females differed significantly from a 1: 1 ratio with the highest ratio being obtained on the west .. coast (3 males: 1 female). At all sites, the populations of H pectunculus exhibited strong sexual dimorphism. Males and females were always found to differ in size, with individuals of < 20 mm shell length generally being male whilst limpets with a shell length of> 22 mm were generally female. Helcion pectunculus grows allometrically, increasing in height faster than length, which is expected of a high shore gastropod mollusc attempting to reduce evaporative water loss. Growth rates were similar on both east and west coasts regardless of the differing oceanographic conditions. The theoretical values of Lmax were also similar being 30.86 mm and 30.71 mm respectively. Micro-growth bands are laid down within its' shell which have the same periodicity as the tidal cycle and these enabled age estimates to be made. Younger individuals were male whilst older animals were female, suggesting that H pectunculus is a protandrous hermaphrodite. Histological examination proved, unequivocally, that this limpet undergoes a protandric sex change, changing from male to female when they are about 2 years old. Both east and west coast popUlations had a marked reproductive cycle, exhibiting two spawning periods a year, one in April and another in November. The possibility that the reproductive pattern exhibited is now phylogeneticallyconstrained is discussed. It is suggested that H pectunculus has evolved a reproductive cycle which will allow its planktonic larvae to utilise the valuable phytoplankton bloom food source whilst using onshore winds to ensure that larvae are not transported out to sea and lost. The number of foraging excursions carried out by individuals of H pectunculus was found to have a significant effect on Gonad Index and hence potential reproductive output. The activity pattern of H pectunculus varied depending upon micro-habitat; animals inhabiting both east and west facing rock surfaces are active during nocturnal low tides whilst animals on west facing rock surfaces are also active during daytime low tides whilst in the shade. Limpets travel further during foraging excursions in winter (X = 85.53 cm) than in either spring (x = 55.7 cm) or summer (X = 48.8 cm) and also during spring low tides (x = 89.8 cm) compared with neaps (x = 40.9 cm). This limpet exhibits rigid homing to a fixed scar within a-crevice and feeding excursions were found to cons.is.t. of three distinct phases, a rapid outward phase, a slower foraging phase and a rapid homeward phase. Foraging was always highly directional, with a mean vector which took limpets onto an area of the rockface with the highest microalgal biomass and also the smoothest rock surface. Helcion pectunculus exhibits a free-running endogenous rhythm of locomotor activity with both circadian and circatidal components and it is suggested that this rhythm plays a role in allowing the limpet to avoid unfavourable environmental conditions. The exogenous entrainment factor of this endogenous rhythm was the time of exposure to air in the field. There was found to be an organized distribution of limpets within crevices with smaller, younger limpets being towards the back of the crevice and larger, older limpets towards the crevice mouth. It is hypothesized that juvenile limpets of this species actively select and settle at the backs of crevices responding to chemical cues of adult conspecifics. The crevice refuge supplies the limpets with a stable and buffered environment with higher relative humidities (X = 72.3%) and lower rock surface temperatures (X = 19.7°C) than adjacent exposed rock surfaces (X = 64.5%; x = 22.9°C). Limpet body temperatures were significantly lower in crevic~refuges compared to limpets on exposed rock surfaces. Body temperatures never exceeded the rock surface temperatures. It is suggested that this is the result of morphological adaptations such as shell ornamentation and allometric growth. Light levels above 1000 J.1E.m-2.s-1 inhibited foraging activity in H. pectunculuswhilst limpets subjected to 30-50% shade foraged even during daytime lowtides. This limpet is one of the least tenacious (2.75 ± 0.13 kg.cm-2 ) of all South African limpets and the possibility that wave activity governs both the activity patterns and homing behaviour of this limpet is discussed. Limpets deprived of a crevice refuge experienced extremely high mortalities, with 45% of the limpets being lost during the first high tide period. A hypothetical model of the hierarchy of exogenous factors controlling limpet foraging activity is introduced and discussed in relation to the results of this study. Finally, it is suggested that in addition to the "migratory" and "non-migratory" groups of limpets present on southern African shores a third group of limpets seem to be present which may be classed as "specialized non-migratory" species. These are species that do not migrate, garden or aggressively fight off like conspecifics. They have overcome the competition for space and food on intertidal rocky shores by adapting to a particular habitat which is exclusive to them alone. From the combined results of these studies, it can be stated that H. pectunculus has adapted physiologically, morphologically and behaviourally to successfully survive the extreme conditions in the upper Balanoid zone.

Orientador: Vera Nisaka Solferini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-27T00:56:04Z (GMT). No. of bitstreams: 1 Salloum_PriscilaMadi_M.pdf: 769704 bytes, checksum: d9254ea3504160fbbd563282b7d46eb7 (MD5) Previous issue date: 2015 / Resumo: A estrutura genética de populações marinhas pode ser avaliada de dois modos: espacial e temporal. Nesse ambiente, fatores diferentes funcionam como barreiras ao fluxo gênico para espécies distintas, apesar da expectativa de que animais com grande capacidade de dispersão apresentem populações panmíticas ao longo de sua distribuição. Echinolittorina lineolata (D¿Orbigny 1840) é um gastrópode comum na costa brasileira e que apresenta larvas com elevada capacidade de dispersão, sendo um interessante modelo para avaliar estrutura genética em ambiente marinho. Este trabalho utilizou abordagens espacial e temporal para avaliar a variabilidade genética e a estrutura populacional de E. lineolata em duas praias do estado de São Paulo. Quatro coletas de juvenis dessa espécie foram feitas em intervalos de 40 dias; três regiões do DNA mitocondrial foram utilizadas como marcadores moleculares, sendo duas regiões do gene citocromo-b (Cyt-b) e uma do gene citocromo oxidase I (CO-1). Os índices de diversidade haplotípica e nucleotídica foram baixos, o que é semelhante a outras espécies marinhas. Redes de haplótipo, análises de variância molecular e a estatística FST evidenciaram estrutura genética entre amostras das duas praias (espacial) e entre amostras das quatro coletas (temporal). Dois fatores foram considerados como prováveis geradores da estrutura genética observada nesses juvenis de E. lineolata: variações geográficas ou oceanográficas locais e variância no sucesso reprodutivo / Abstract: The genetic structure of marine populations can be evaluated by two modes: spatial and temporal. In this environment, different factors work as barriers to gene flow for different species, although animals with high dispersal ability are expected to present panmitic populations along their range. Echinolittorina lineolata (D¿Orbigny 1840) is a common gastropod on the Brazilian coast and has larvae with high dispersal ability, being an interesting model to evaluate genetic structure in the marine environment. This work used spatial and temporal approaches to evaluate the genetic variability and population structure of E lineolata in two beaches of the São Paulo state. Four collections of juveniles were done in 40-days intervals; three regions of the mitochondrial DNA were used as molecular markers: two from cytochrome-b gene (Cyt-b) and one from cytochrome oxidase I gene (CO-1). The haplotype and nucleotide diversity indexes were low, similar to other species. Haplotype networks, analyses of molecular variance and FST statistics indicated genetic structure among the two beaches¿ samples (spatial) and among the four collections¿ samples (temporal). Two factors were considered as likely drivers of the observed genetic structure on these juveniles: local geographic or oceanographic variations and variance in the reproductive success / Mestrado / Genetica Animal e Evolução / Mestra em Genética e Biologia Molecular

No description available.

The large gumboot chiton, Cryptochiton stelleri, (Middendorf, 1846) annually undergoes a reproductive cycle terminated by spawning in the spring. Cryptochiton stelleri is one of the marine invertebrates which possess carotenoid prognosis. Cryptochiton acquired its carotenoid moiety from the algae upon which it feeds. Following digestion carotenoids are transported to various sites in the body. The mechanisms and routes of this transport, as well as the eventual fate of the carotenoids in nutrition, are unknown. Perhaps storage in the animal occurs because of an inability to eliminate the carotenoids. On the other hand, the presence of carotenoids in the gonads would suggest a relationship to reproduction. Especially interesting in the appearance of the green pigment in the egg during maturation. The investigation of any of the foregoing considerations requires convenient methods of analysis. One of the first steps of analysis in the discovery of an extracting solvent. It is the purpose of this paper to describe several experiments carried out to find extracting solvents for the removal of the green pigment from the eggs of Cryptochiton, as well as some preliminary investigation into the pigment’s nature. Also described are several experiments relating the studies upon the carotenoids found in the gonads of both sexes of Cryptochiton.

Ferrissia rivularis was selected for research because of its local accessibility and because essentially nothing was known of its reproduction and development. Reproductive and developmental biology is first described herein from the natural environment. This is then compared with the effects created by experimental exposure to a selected herbicide, maleic hydrazide, which might be a potential threat to certain invertebrates in the natural environment.

No description available.

No description available.

published_or_final_version / abstract / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Master / Master of Philosophy

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy