The Behaviour and Ecology of Austrolittorina antipodum and Austrolittorina cincta: Models for Marine Reserve Connectivity Studies

<p>Determining the magnitude of dispersal and connectivity between populations has important implications for marine conservation. Species with limited dispersal capabilities exhibit restricted gene flow leading to isolation and, ultimately, differentiated populations. In this ecological study I investigated the gastropods Austrolittorina antipodum (Philippi, 1847) and Austrolittorina cincta (Quoy and Gaimard, 1833) to determine how ecology and behaviour influence the dispersal and connectivity of these species. The aim of this study was to determine population size and structure, settlement, fecundity, and adult movement rates. Methodologies included: population surveys, deployment of settlement pads and adult density manipulations, dissections, and a tagging study. These elements of a species ecology and behaviour can enhance or restrict population connectivity by: cohort partitioning resulting from habitat requirements, fluctuating settlement due to variable larval mortality or adult densities impacting dispersal, skewed sex ratios and effective populations sizes altering larval production, and adult movement leading to behavioural isolation or facilitating gene flow, along with other possible effects. Population surveys revealed both species had a Vermeij (1972) "type 1 distribution" (shell size increasing from the low to high shore), with the highest density of individuals on the low shore and the majority of mature adults on the high shore. Overall, A. antipodum was 16 times more abundant than A. cincta. Shifts to a smaller mean size of both species, along all shore heights following periods of peak settlement indicates settlers are potentially triggering competitive interactions or ontogenetic migrations in other cohorts.Settlement surveys revealed that peak settlement for Austrolittorina spp. was from February to April, declining at the beginning of March. Multiple peaks in settlement may act as a buffer limiting the potential of stochastic events to hinder dispersal during reproductive seasons. Settlement rates were not affected by adult density in control treatments; however, settlement was higher on pads deployed within adult populations compared to pads deployed adjacent to adult populations, suggesting the presences of adults has some effect on settlement. Fecundity results revealed A. antipodum to have more mature females than A. cincta, with males of both species reaching sexual maturity before females. Sex ratios of both species were skewed towards more females, with effective population sizes that included approximately 88% of each species population. A. antipodum’s larger population may be due to variation between the species' demographics, such as the distribution of mature females and juveniles leading to greater spawning success and juvenile survivorship. Tagging transplant/translocation experiments used to examine movement revealed that both species traveled similar distances. On average A. antipodum traveled 24.1m (±23.5m) and A. cincta traveled 18.7m (±16m) in eight months. There was no evidence of behavioural isolation occurring between low and high shore individuals. The wide ranging movements of adults indicated adults have the potential to maintain population connectivity on small scales. The findings of this study suggest both species facilitate dispersal with multiple peaks in settlement, large effective populations, and high adult mobility. Behavioural variation between the species appears to affect population connectivity, with the distribution of A. antipodum demographics potentially enhancing connectivity.</p>

The Behaviour and Ecology of Austrolittorina antipodum and Austrolittorina cincta: Models for Marine Reserve Connectivity Studies

<p>Determining the magnitude of dispersal and connectivity between populations has important implications for marine conservation. Species with limited dispersal capabilities exhibit restricted gene flow leading to isolation and, ultimately, differentiated populations. In this ecological study I investigated the gastropods Austrolittorina antipodum (Philippi, 1847) and Austrolittorina cincta (Quoy and Gaimard, 1833) to determine how ecology and behaviour influence the dispersal and connectivity of these species. The aim of this study was to determine population size and structure, settlement, fecundity, and adult movement rates. Methodologies included: population surveys, deployment of settlement pads and adult density manipulations, dissections, and a tagging study. These elements of a species ecology and behaviour can enhance or restrict population connectivity by: cohort partitioning resulting from habitat requirements, fluctuating settlement due to variable larval mortality or adult densities impacting dispersal, skewed sex ratios and effective populations sizes altering larval production, and adult movement leading to behavioural isolation or facilitating gene flow, along with other possible effects. Population surveys revealed both species had a Vermeij (1972) "type 1 distribution" (shell size increasing from the low to high shore), with the highest density of individuals on the low shore and the majority of mature adults on the high shore. Overall, A. antipodum was 16 times more abundant than A. cincta. Shifts to a smaller mean size of both species, along all shore heights following periods of peak settlement indicates settlers are potentially triggering competitive interactions or ontogenetic migrations in other cohorts.Settlement surveys revealed that peak settlement for Austrolittorina spp. was from February to April, declining at the beginning of March. Multiple peaks in settlement may act as a buffer limiting the potential of stochastic events to hinder dispersal during reproductive seasons. Settlement rates were not affected by adult density in control treatments; however, settlement was higher on pads deployed within adult populations compared to pads deployed adjacent to adult populations, suggesting the presences of adults has some effect on settlement. Fecundity results revealed A. antipodum to have more mature females than A. cincta, with males of both species reaching sexual maturity before females. Sex ratios of both species were skewed towards more females, with effective population sizes that included approximately 88% of each species population. A. antipodum’s larger population may be due to variation between the species' demographics, such as the distribution of mature females and juveniles leading to greater spawning success and juvenile survivorship. Tagging transplant/translocation experiments used to examine movement revealed that both species traveled similar distances. On average A. antipodum traveled 24.1m (±23.5m) and A. cincta traveled 18.7m (±16m) in eight months. There was no evidence of behavioural isolation occurring between low and high shore individuals. The wide ranging movements of adults indicated adults have the potential to maintain population connectivity on small scales. The findings of this study suggest both species facilitate dispersal with multiple peaks in settlement, large effective populations, and high adult mobility. Behavioural variation between the species appears to affect population connectivity, with the distribution of A. antipodum demographics potentially enhancing connectivity.</p>

Effect of Alternative Fillers on the Properties of Rubber Compounds

The paper is focused on the influence of alternative fillers on rubber compounds properties. Three different types of powder fillers, drinking water treatment sludge (DWTS), perlite and calcium carbonate, were mixed into rubber compound mixtures. The mixtures were composed of STR20, EPDM, zinc oxide, steric acid, paraffin wax, 2-mercaptobenzothiazole (MBT), sulphur, Wingstay L, and filler. The mixtures were mixed in a Kneader type mixer at temperature of 70°C and then continuously mixed using a two-roll mill at temperature of 70°C. The relationships between type and the amount of filler versus properties of rubber compounds were demonstrated. The results showed that tensile and elongation at break of rubber compounds gradually decreased with increasing the amount of filler. Rubber compounds filled with small particle size filler possessed higher tensile strength and elongation at break than those filled with large particle size filler. Values of DIN abrasion loss of rubber compounds prepared under proper mixing condition were not more than 300 mm3. Under appropriate condition, the rubber compounds with DWTS, perlite and calcium carbonate provided sufficiently high shore A hardness (not less than 50 Shore A hardness). Finally, alternative fillers such as DWTS and perlite were expected to replace calcium carbonate in normal formula.

Gastropod diversity at Pulau Punyit and the nearby shoreline – a reflection of Brunei’s vulnerable rocky intertidal communities

Pulau Punyit (PPUN), a small islet on the South China Sea coastline of Brunei Darussalam, represents a significant portion of the country’s natural rocky-shore ecosystem. We carried out a rapid survey of the intertidal gastropod species richness at PPUN, and compared this with species richness at other nearby natural and artificial rocky shores [Tungku Punyit (TPUN), Pantai Jerudong (PJER), Jerudong Park Medical Centre (JPMC) and Pantai Tungku (TUNK)]. A total of thirty two (32) species were collected from all of the shores. Species richness was greatest at the two natural shores studied (numbering 21 and 22 species at PPUN and TPUN, respectively), while the artificial shores were relatively depauperate. The natural shores however differed in species composition, abundance and body size of gastropods. These attributes varied with shore height, and appeared to relate to height-specific differences in abiotic stresses at the shores - at PPUN the high-shore is more exposed to the wind and sun, whereas at TPUN the mid-shore experiences greater sedimentation and mainland acidic seepage. Faunistic differences between the artificial and natural shores (Bray-Curtis similarity analysis) seemingly associate more closely with degree of habitat availability and abiotic stress than with shore proximity. We conclude that the country’s rocky intertidal biodiversity, as reflected by the gastropod diversity, is mainly constituted by the natural rocky shore system. Because this is spatially constrained and vulnerable to locality-specific environmental stresses, this diversity is threatened and deserving of greater protection status.

Site fidelity, size, and morphology may differ by tidal position for an intertidal fish,Bathygobius cocosensis(Perciformes-Gobiidae), in Eastern Australia

The intertidal zone is a transitional environment that undergoes daily environmental fluctuations as tides rise and fall. Relatively few fish species are adapted to endure the physiological pressures of this environment. This study focused onBathygobius cocosensis(Gobiidae), a common intertidal fish in New South Wales, Australia. We investigated whether shore height impacted site fidelity, survival probability, fish size, and morphological traits with respect to tidal height. Mark-recapture methods were used over a five month period to determine if individuals in high shore pools had greater site fidelity; fish in high tide pools were more than twice as likely to be recaptured in their original pool than fish from low tide pools. High pool individuals were, on average, smaller with larger eyes and longer snouts relative to their size as compared to low pool individuals. We discuss several mechanisms that could cause the observed pattern in morphological variation. Ultimately, this study suggests that within species behaviour and morphology differ by tidal position for an intertidal fish.

On the reproduction of the Mediterranean keystone limpet Patella rustica: histological overview

The reproductive cycle of the high shore limpet Patella rustica is described based on histological analysis as the primary method of staging gonad development. Sex-ratios, shell length at sexual maturity, gonad developmental stages, mean gonad index and oocyte size were investigated. Males and females were found to differ in size distribution, with females becoming more prevalent from ~28 mm onwards. The estimated shell length at which 50% of males were sexually mature was 13.1 mm. Patella rustica has only one reproductive cycle per year with a spawning peak between November and December for both sexes, and gonad redevelopment from January. First data on the size–frequency analysis of oocytes for this species are also presented, concurring with the qualitative analysis of the gonad developmental stages. This study presents updated information on the reproductive cycle of this keystone species and provides the first account of the reproductive biology of P. rustica in the Adriatic Sea.