Aspects of the biology and ecology of Patella granularis were investigated along a 130km stretch of the south-east coast of South Africa. Distribution, biomass, density and population structure were investigated at seven localities. In addition, a more detailed study of the growth rate and reproductive biology of populations inhabiting three different substrata (aeolianite, quartzitic sandstone and mussel shells) was conducted. The genetic relationships between these three populations was also examined, as was the foraging behaviour of the limpets inhabiting an aeolianite and a quartzitic sandstone shore. Finally, differences in food availability on the different substrata were studied. On the south-east coast, P. granularis has a wide intertidal distribution, occurring from the upper Balanoid zone through to the Cochlear zone, where it is a common inhabitant of mussel shells. The mean shell length of P. granularis was found to decrease down the shore. The largest limpets (46.6 mm shell length) were found on an offshore island in Algoa Bay. At most localities investigated, the sex ratio deviated from a 1:1 ratio with more males than females being recorded on five shores. Both limpet density and biomass were lower on the south-east coast when compared to data published for west coast populations. On the south-east coast, both density and dry biomass were highest in the lower Balanoid zone. Allozyme electrophoresis indicated that P. granularis inhabiting aeolianite, quartzitic sandstone and mussel shells are all part of a single population. Extremely high genetic identity values (0.998), low levels of heterozygosities (0.035 - 0.061), low levels of polymorphisms (25% - 31%) and low FST values (0.021) all suggest that the three populations of P. granularis form a common breeding group, despite the high levels of phenotypic plasticity observed. On all shores, P. granularis was found to grow allometrically, increasing in shell height more rapidly than shell length. Estimation of the growth rate (determined by the Von Bertalanffy growth model) of P. granularis suggested that limpets inhabiting the mussel shells grew more slowly, and attained a smaller maximum size, than those inhabiting both the aeolianite and the quartzite (K = 0.25, 0.32 and 0.33 respectively; 27.12 mm, 31.89 mm and 32.96 mm respectively). Previous work has shown that west coast P. granularis grow more quickly (K = 0.7) and reach a greater size (. 40 mm). Translocation of limpets among sites suggested that limpet size in the mussel beds was spatially constrained. Shell microgrowth bands were deposited tidally, but could not be used for aging limpets due to shell erosion. Limpets from the aeolianite had the greatest reproductive fitness, producing more eggs (.366 000/limpet) than those inhabiting quartzite (.119 500/limpet) or mussel shell limpets (.85 800/limpet). Aeolianite limpets also spawned throughout the year, whereas those from the quartzite and mussel shells spawned twice a year (once in winter and once in summer) although a great deal of interannual variability was observed. The onset of sexual maturity occurred at a similar age in all limpets (1 - 2 years) and is probably genetically entrenched. P. granularis inhabiting both an aeolianite and a quartzitic shore were active during nocturnal low tides. All limpets returned to a home scar after foraging. Whilst foraging, limpets inhabiting the aeolianite shore moved shorter distances (.17 cm) at a slower rate than those from quartzite (.30 cm). Limpets that were translocated from one substratum to the other initially moved similar distances to the source group, but after a maximum period of one week, moved distances that mirrored those moved by the resident limpets. Neither season nor tidal phase influenced the distances foraged. No directionality in foraging was found. Wear of radula teeth, particularly the pluricuspid tooth, was greater in limpets from the quartzite. It is hypothesised that the observed differences in life-history parameters and foraging behaviour of limpets both within the south-east coast and between the west and south-east coasts are related to food abundance. Chlorophyll-a, and hence microalgal biomass, was consistently higher on aeolianite (.2.5 times) than on both quartzite and mussel shells. Estimates of chlorophyll-a were higher (although not significantly) in winter. Previous studies determined that primary productivity is also higher along the west coast. Finally, the lack of evidence for migration of limpets from the low-shore to high-shore in south-east coast P. granularis is discussed. It is suggested that this species settles opportunistically within its physiological tolerances and responds morphologically to localised environmental conditions.

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.

This thesis is a report of the findings of two years of part-time work on the limpets of the family Acmaedae. The major portion of the work was done on the Monterey Peninsula between Point Pines, 36° 38' 30" N. latitude, 121° 56' 00" W. longitude, and Pescadero Point 30° 33' 40" N. latitude, 121° 56' 30" W. longitude. The work on homing in Acmaea persona, artificial parthenogenesis in the eggs of Acmaea pelta, and artifical insemination of the eggs of Acmaea pelta was carried on at the Pacific Marine Station, Dillon Beach, California at 38° 14' 30" N. latitude, 122&176; 58' 30" W. longitude during the summer of 1947.

published_or_final_version / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 176-192). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 202-237). / Microfiche. / xvi, 237 leaves, bound ill., photos. 29 cm

Limpets are harvested by people in South Africa, but are selected in terms of species and size. The effects of marine reserves on the biology of commonly exploited (Helcion concolor and Scutellastra longicosta) and rarely exploited species (Cellana capensis and Scutellastra granularis) were investigated on the southeast coast of South Africa at two reserve and two non-reserve sites. For each species, a 4-way nested ANOVA was used to test the effects of month, reserve, site (nested within reserve) and area (nested within site and reserve) on population density, size structure and recruitment of these limpets. The data were collected monthly over 20 months. The overall results indicated a gradient of exploitation among species, S. longicosta was the most heavily exploited species and S. granularis the least exploited species. However, there was also a gradient of exploitation between reserves and non-reserves. Xhora was the most heavily exploited site while Nqabara was less heavily exploited. Of the two reserve sites, Cwebe had more poachers than Dwesa. In most analyses, the month x area (reserve (site)) interaction was significant. However, this was largely an artifact due to comparisons of areas in different sites and significant differences between areas within sites occurred in relatively few months. Densities were greater inside reserves for all species except C. capensis. For S. longicosta and H. concolor this was expected but not for S. granularis and the result possibly reflects its opportunistic exploitation in the absence of the preferred species or indirect effects of reserves. Commonly exploited species and the rarely exploited C. capensis clearly showed greater mean and maximum sizes in reserves but there were month/site (reserve) interactions. Months with significant differences between reserves and nonreserves in both mean and maximum sizes generally occurred more often for commonly exploited than rarely exploited species, but C. capensis showed the strongest reserve effect on maximum size. Interview surveys showed that, although not normally exploited, C. capensis is sometimes mistaken for H. concolor and this suggests that large individuals are unintentionally harvested outside reserves. There were no significant reserve effects on recruitment for any species. Although Xhora had the lowest densities and limpet sizes, it showed the highest recruitment especially for S. longicosta, suggesting that larvae can be transported far from where they are released and settle in non-reserve sites regardless of adult densities. Reserve as a main factor was not significant for the rarely exploited species, but there was a significant month x reserve interaction, with non-reserves having greater GSI values than reserves in most months. Growth rates were examined using individual tagging and cohort analysis. The two techniques gave different results, with individual tagging giving higher growth estimates than cohort analysis. Except for the territorial species S. longicosta, growth was higher in non-reserves and inversely correlated with population density. Mortality estimates using the Cormack-Jolly-Seber model indicated that the rarely exploited species had significantly greater capture probabilities in reserves while no significant reserve effects were observed for the commonly exploited species. Reserve effects on survival probability were significant only for S. longicosta, with reserves being greater than nonreserves and no significant effects for any other species. Enhanced survival in reserves was attributed to the effects of human exploitation. In theory, marine protected areas show increases in densities, sizes and reproductive output of exploited species, but the present results revealed that the efficacy of reserves depends on the status of the species, not only whether it is exploited or non-exploited, but also whether it is territorial.

This thesis is divided into two parts. The first part (Chapter Two) documents a bioassay guided investigation of the ethyl acetate extracts of four marine invertebrates from Mozambique (an Irciniid sponge, a Haliclona sp. sponge, an ascidian tentatively identified as Diplosoma sp., and the soft coral Cladiella kashmani). Eight known compounds [ilimaquinone (2.1), renierone (2.7), N-formyl-1,2-dihydrorenierone (2.8), 1,6-dimethyl-7-methoxy-5,8-dihydroisoquinoline-5,8-dione (2.9), mimosamycin (2.10) 7Z-allylidene-5-hydroxy-7,7a-dihydro-2H-cyclopenta[b]pyran-6-one (2.11), flaccidoxide (2.18) and 11S,12S-epoxycembra-1Z,3E,7E-trien-14S-ol (2.19)] and a new diterpene [13S,14R-diacetoxy-11S,12R-epoxycembra-1Z,3E,7E-triene (2.20)] were isolated and identified using standard spectroscopic techniques. Anomalies in the published spectral data of 2.1 and 2.8 were exposed and corrected, and the absolute stereochemistry of the cembrane diterpenes 2.18 and 2.20 established using the modified Mosher’s method. The comparative activities of the nine natural products against four cancer cell lines (A549, LOX, OVCAR3, SNB19) are reported. The second part of the thesis (Chapter Three – Chapter Six) is concerned with an ecological, structural and synthetic study of diterpenes from the endemic South African pulmonate limpet Trimusculus costatus. Two new labdane diterpenes [6b,7a-diacetoxylabda-8,13E-dien-15-ol (3.10) and 2a,6b,7a-triacetoxylabda-8,13E-dien-15-ol (3.11)] were isolated from T. costatus and evaluated for anti-feeding activity against the common predatory fish Pomadasys commersonnii. A strategy for the semi-synthesis of 3.10 from rhinocerotinoic acid (4.14), a diterpene reportedly present in the ubiquitous South African shrub Elytropappus rhinocerotis, was devised in order to allow further bioactivity tests to be performed and unequivocally assign the unknown absolute stereochemistry of the T. costatus metabolites. Attempts to isolate rhinocerotinoic acid from local specimens of Elytropappus rhinocerotis were unsuccessful, and as the repetition of a published synthesis of 4.14 from (-)-sclareol (4.15) gave rhinocerotinoic acid in unacceptably low yields with poor stereoselectivity, an improved synthesis of 4.14 is presented. Comprehensive studies using hispanone (5.1) as a model compound showed that 6,7-dioxygenated labda-8-enes could be prepared from compounds possessing a 7-oxo-labda-8-ene skeleton with some degree of stereocontrol. In the process, fourteen new hispanone analogues were prepared and most of these were tested for activity in a suite of ten agro-chemical assays. The novel compound 7b-hydroxy-9a-carbonitrile-15,16-epoxylabda-13(16),14-dien-6-one (5.34) exhibited significant activity against the crop fungus Phytophthora infestans and is currently being subjected to further agro-chemical tests. Unfortunately, the results from the oxygenation study performed on the model compound 5.1 could not be directly extrapolated to rhinocerotinoic acid. Attempts to prepare the naturally occurring 3.10 from 4.14 via an alternative route were unsuccessful but yielded an analogue of 3.10 in which the substituents at C-6 and C-7 are in a diequatorial rather than a diaxial configuration.

Os ecossistemas costeiros sofrem impactos antrópicos de fontes diversas, entre eles os despejos de efluentes, que podem potencializar o desenvolvimento de produtores primários em costões rochosos resultante do enriquecimento por nutrientes. Ao mesmo tempo, o crescimento dos produtores pode ser controlado pela presença dos herbívoros. No presente estudo buscamos descrever o efeito dos despejos de efluentes sobre o acúmulo de biofilme em costões rochosos, sob diferentes níveis de despejos de efluentes em uma área subtropical (São Paulo, Brasil), bem como o efeito dos efluentes sobre as lapas. Estimamos a biomassa do biofilme in situ, por medidas indiretas de NDVI e por análises taxonômicas de amostras fixadas. A estrutura populacional de lapas foi descrita por contagem e medição do comprimento da concha. Um experimento em campo foi realizado sob presença e ausência de efluentes, bem como presença e ausência de lapas. Observamos que o efeito de efluentes potencializa o acúmulo de biofilme, entretanto não observamos um consumo significativo das lapas sobre o biofilme. O tamanho e densidade de lapas não foram alteradas pelo gradiente de efluentes. Em geral, foi observada uma predominância de diatomáceas em relação às cianobactérias, o que pode diferir da tendência de dominância de cianobactérias verificada em outras regiões. É importante ressaltar a importância de outros pastadores sobre o desenvolvimento de biofilme, não considerados neste estudo, além da alta variabilidade temporal e espacial que as comunidades de biofilme apresentam. Ressaltamos a importância da aplicação de organismos bentônicos como indicadores da qualidade do ambiente. / Coastal ecosystems suffer anthropogenic impacts from many sources such as sewage disposal, which may potencialize de primary productors growth in rocky shores. In the same time, this growth amy be controlled by grazers. In this study we aimed to investigate the biofilm accumulation in rocky shores under different level of sewage disposal in a subtropical area (São Paulo State, Brazil), and its influence on the grazers. The biofilm biomass was estimated in situ indirectly by NDVI measures and taxonomic analysis of fixed samples. The size structure of limpets was described through counting and measurement of the shell length. We also performed a field experiment under presence and ausence of sewage, as presence and ausence of limpets. We observed a sewage effect improve the biofilm accumulation, but the limpets did not have a clear control on the biofilm growth. No clear effect of sewage disposal was verified on the size and density of limpets. In general, we observed a domination of diatoms relative to cianobacterias, which could differ of the trend observed in another sites. It is noteworthy that the possible effects of other grazers on the biofilm were not quantified and the high temporal and spatial variability of biofilm communities. We emphasize the importance of studies that use benthic organisms as environmental quality indicators.