No description available.

The purpose of this study was to examine the masking preferences of the spider crab, Notomithrax ursus. The algal composition of the mask in the natural habitat at Kaikoura was examined to determine the general rules the crab follows when decorating itself. The effects of size and sex on the mask composition were examined, as well as determining how the composition of the mask varies by body part. The preference of the crabs was further examined through the use of choice and background change experiments in the laboratory. It was determined that the preference of certain types of algae for mask material is not entirely dependent on their relative abundance in the environment. Possible explanations for this behaviour are given.

Made available in DSpace on 2014-06-11T19:35:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-14Bitstream added on 2014-06-13T20:07:21Z : No. of bitstreams: 1 santanna_bs_dr_rcla.pdf: 1220451 bytes, checksum: 128147c372ab63a9112c55e0cc7fff0e (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A causa da intersexualidade em ermitões ainda é desconhecida. No presente estudo foi avaliada a relação entre a intersexualidade em ermitões e o poluente disruptor endócrino tributilestanho (TBT), como registrado para gastrópodes. A contaminação em populações naturais do ermitão Clibanarius vittatus também foi investigada. Compostos butílicos (Bts) foram determinados em tecidos de ermitões e sedimentos usando cromatografia gasosa e análises morfológicas foram desenvolvidas por histologia e microscopia eletrônica, em amostras provenientes da natureza e de experimentos controlados. A avaliação do ambiente mostrou que localidades com e sem atividades portuárias estão contaminadas com elevadas concentrações de Bts, mesmo após o banimento do TBT. Estes dados indicam que Bts continuam sendo liberados no ambiente ou que estes compostos estão acumulados em diferentes compartimentos do ambiente. O registro de ermitões contaminados por Bts em muitos locais onde não foram detectados no sedimento sugere que ermitões são melhores indicadores de Bts do que sedimentos, porque não representam apenas a contaminação pontual. Além disso, os experimentos revelaram que a principal forma de assimilação do TBT por C. vittatus é proveniente da alimentação. Em adição, a rápida depuração do TBT, o hábito de vida em regiões estuarinas, tamanho relativamente grande, longo ciclo de vida e sua baixa mobilidade faz dessa espécie e de ermitões estuarinos em geral bons candidatos a indicadores de contaminação recente de TBT. As análises morfológicas mostraram que indivíduos intersexo apresentaram gônadas funcionais de macho e fêmea no mesmo indivíduo. Estes dados confirmam que ermitões intersexo podem reproduzir como machos ou fêmeas suportando a hipótese de que eles podem ser parte de um processo hermafrodita verdadeiro. A hipótese de que o TBT está relacionado... / The causes of intersexuality in hermit crabs are still unknown. This study was carried out to evaluate the relationship between intersexuality and endocrine disruption caused by tributyltin (TBT) pollution, as previously reported for gastropods. In addition, it was also investigated the TBT contamination in natural populations of the hermit crab Clibanarius vittatus. Butiltins (Bts) in hermit crabs tissues and sediments were analysed by gas chromatography and the morphological analysis was carried out by histology and scanning electron microscopy using samples from both nature and controlled experiments. The evaluation of contamination in nature showed that localities with and without harbor activities are contaminated by high concentrations of Bts, even though the ban regulamentation of TBT. These data indicate that Bts compounds are still being released in the environment or they are accumulated in different environmental compartments. The record of contaminated hermit crabs by BTs in many places where contaminated sediments by BTs was not detected suggest that hermit crabs are better indicators of BTs than sediments, because of their contamination was not only represented punctually. Furthermore, the controlled experiments in laboratory showed that, the main TBT uptake pathway for C. vittatus is from food. In addition, the fast depuration of TBT, estuarine habitat, relatively large body sizes, long life spans, and relatively low mobility make this species and estuarine hermit crabs in general very good candidates as indicators of recent or recycled TBT contamination. The morphological analyses showed that the intersex individuals developed functional male and female gonads in the same individual. These data confirmed that intersex hermit crabs can reproduce as males or females supporting the hypothesis that they may be part of a true sequential hermaphroditic process... (Complete abstract click electronic access below)

Orientador: Maria Lucia Negreiros-Fransozo / Banca: Roberto Shimizu / Banca: Rogério Caetano da Costa / Resumo: O início do ciclo de vida dos caranguejos braquiúros possui uma fase planctônica de dispersão que consiste de um número variável de estágios de zoea, seguido por um estágio de decapodito, denominado megalopa. As megalopas passam por um transporte horizontal até os locais de assentamento onde sofrem metamorfose para o primeiro estágio juvenil. Apesar da importância da fase larval na dinâmica das populações de caranguejos estuarinos, existe pouca informação sobre a mesma. Este estudo avalia a distribuição espacial das megalopas ao longo do estuário de Ubatumirim, Ubatuba, SP. As amostragens foram realizadas em épocas de marés de amplitude de quadratura e em marés com amplitude de sizígia, durante os meses de Abril e Novembro de 2005. As megalopas foram capturadas com coletores artificiais passivos, confeccionados a partir de material vegetal, em dez estações de coleta no estuário de Ubatumirim. As estações estavam dispostas a, aproximadamente, 200m de distância um do outro. No laboratório, as larvas coletadas foram identificadas de acordo com a literatura disponível. A distribuição das megalopas próximo às margens e ao centro do canal do rio em cada estação de coleta foi avaliada. A ocorrência dos diferentes táxons de Brachyura registrados em cada estação de coleta foi correlacionada com as variáveis ambientais: temperatura da água, salinidade, velocidade de corrente e profundidade, por meio de uma análise de correlação canônica. O maior número de indivíduos foi registrado nas estações mais próximas ao mar. Dois principais grupos taxonômicos predominaram nas amostras, os sesarmídeos e ocipodídeos. Houve diferença significativa entre a abundância de larvas em períodos de marés de quadratura e sizígia. Entre as famílias Sesarmidae e Ocypodidae não foi verificada nenhuma diferença estatística quanto distribuição... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The early life cycle of brachyuran crabs has a planktonic dispersal phase consisting of a variable number of zoeal larvae followed by the molt to the megalopa stage. Megalopae undergo horizontal transport to the settlement site where they settle out of the water column and metamorphose to the first juvenile stage. In spite of the importance of the larval phase on population dynamics of estuarine crabs, there is little available information of its phase. The goal of the present study was to evaluate the spatial distribution of megalopae throughout the estuary of Ubatumirim river, Ubatuba, SP. Periodic samples were carried out in periods of neap tides and spring tides in April and November 2005. The megalopae of Brachyura were collected on passive collectors made from a natural substrate at ten sampling sites within Ubatumirim estuary. The horizontal distance between two sites was approximately 200m. At the laboratory, larvae were identified according to available literature. The lateral distribution of megalopae in each collecting site was evaluated. The occurrence of megalopae of different taxa in each site was correlated with the environmental variables: water temperature, salinity, current velocity and depth by means of a canonical correlation analisys. The greater density of megalopae was registered in the sites near the river mouth. Two main groups predominated in the samples, the sesarmid and ocypodid crabs. There was a significant difference in the abundance of larvae between neap and spring tides. However there was no statistic difference in the lateral distribution of megalopae of the families Sesarmidae and Ocypodidae. The principal abiotic factors that are related to the spatial distribution of megalopae were temperature, salinity and current velocity. However, it seems that a group of variables controls the distribution pattern... (Complete abstract click electronic access below) / Mestre

Resumo: A causa da intersexualidade em ermitões ainda é desconhecida. No presente estudo foi avaliada a relação entre a intersexualidade em ermitões e o poluente disruptor endócrino tributilestanho (TBT), como registrado para gastrópodes. A contaminação em populações naturais do ermitão Clibanarius vittatus também foi investigada. Compostos butílicos (Bts) foram determinados em tecidos de ermitões e sedimentos usando cromatografia gasosa e análises morfológicas foram desenvolvidas por histologia e microscopia eletrônica, em amostras provenientes da natureza e de experimentos controlados. A avaliação do ambiente mostrou que localidades com e sem atividades portuárias estão contaminadas com elevadas concentrações de Bts, mesmo após o banimento do TBT. Estes dados indicam que Bts continuam sendo liberados no ambiente ou que estes compostos estão acumulados em diferentes compartimentos do ambiente. O registro de ermitões contaminados por Bts em muitos locais onde não foram detectados no sedimento sugere que ermitões são melhores indicadores de Bts do que sedimentos, porque não representam apenas a contaminação pontual. Além disso, os experimentos revelaram que a principal forma de assimilação do TBT por C. vittatus é proveniente da alimentação. Em adição, a rápida depuração do TBT, o hábito de vida em regiões estuarinas, tamanho relativamente grande, longo ciclo de vida e sua baixa mobilidade faz dessa espécie e de ermitões estuarinos em geral bons candidatos a indicadores de contaminação recente de TBT. As análises morfológicas mostraram que indivíduos intersexo apresentaram gônadas funcionais de macho e fêmea no mesmo indivíduo. Estes dados confirmam que ermitões intersexo podem reproduzir como machos ou fêmeas suportando a hipótese de que eles podem ser parte de um processo hermafrodita verdadeiro. A hipótese de que o TBT está relacionado... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The causes of intersexuality in hermit crabs are still unknown. This study was carried out to evaluate the relationship between intersexuality and endocrine disruption caused by tributyltin (TBT) pollution, as previously reported for gastropods. In addition, it was also investigated the TBT contamination in natural populations of the hermit crab Clibanarius vittatus. Butiltins (Bts) in hermit crabs tissues and sediments were analysed by gas chromatography and the morphological analysis was carried out by histology and scanning electron microscopy using samples from both nature and controlled experiments. The evaluation of contamination in nature showed that localities with and without harbor activities are contaminated by high concentrations of Bts, even though the ban regulamentation of TBT. These data indicate that Bts compounds are still being released in the environment or they are accumulated in different environmental compartments. The record of contaminated hermit crabs by BTs in many places where contaminated sediments by BTs was not detected suggest that hermit crabs are better indicators of BTs than sediments, because of their contamination was not only represented punctually. Furthermore, the controlled experiments in laboratory showed that, the main TBT uptake pathway for C. vittatus is from food. In addition, the fast depuration of TBT, estuarine habitat, relatively large body sizes, long life spans, and relatively low mobility make this species and estuarine hermit crabs in general very good candidates as indicators of recent or recycled TBT contamination. The morphological analyses showed that the intersex individuals developed functional male and female gonads in the same individual. These data confirmed that intersex hermit crabs can reproduce as males or females supporting the hypothesis that they may be part of a true sequential hermaphroditic process... (Complete abstract click electronic access below) / Orientador: Fernando José Zara / Coorientador: Alexander Turra / Banca: Flávio Henrique Caetano / Banca: Marcos Antônio Fernandez / Banca: Acácio Ribeiro Gomes Tomás / Banca: Maria Lucia Negreiros-Fransozo / Doutor

Philosophiae Doctor - PhD / There has been extensive growth in nanoscale technology in the last few decades to such a degree that nanomaterials (NMs) have become a constituent in a wide range of manufactured commercial and domestic products. This surge has resulted in uncertainties regarding their environmental impact, due to the significant increases in the amount of NMs released into the environment (Dowling et al., 2004) through intentional and unintentional releases. Like many other toxins, the aquatic environment is particularly vulnerable as it acts as a sink for nanoparticles (NPs) (Scown et al., 2010). The escalating growth of NMs has not advanced without efforts to understand its properties. Despite the dramatic advances in both the production and application of NMs, very little is known regarding their interaction with and effects on environmental and human health. Given the lack in scientific knowledge, particularly under various environmental conditions, it is often difficult to accurately assess the potential exposure pathways to ecological receptors of all NMs, silver nanoparticles (AgNPs) are the most widely used NPs, present in several consumer products mainly because of their anti-bacterial properties. It is estimated that the annual production exceeds 1000 tons/year (Piccinno et al., 2012). The increase uses of AgNPs in consumer products (e.g. textiles, cosmetics and personal hygiene), household appliances (e.g. washing machines and vacuum cleaners) and medical equipment have led to their increase release into the environment, thereby posing an environmental risk and human health concern. Silver NPs are known to induce the production of Reactive Oxygen Species (ROS) (Ahamed et al., 2010; Levard et al., 2012; Piao et al., 2011). Also since AgNPs are oxidized to ionic Ag (Ag+), it is still unclear whether the effects of ROS can be attributed to Ag+ release or to the AgNP itself (Fabrega et al., 2009; Miao et al., 2009). The behaviour of AgNPs is collectively influenced by inherent (nanoparticle size, shape, surface area, surface charge, crystal structure, coating, solubility/dissolution) and environmental factors (temperature, pH, ionic strength, salinity, organic matter). Climate change predictions indicate that the frequency, intensity and duration of extreme natural events (such as temperature elevations) will increase in the future (IPCC, 2001; IPCC, 2007). Global warming and climate change could increase atmospheric temperatures by 2.4 – 6.4 °C (IPCC, 2001; IPCC, 2007). The main feature associated with global climate change is the anticipation of wetter winters (i.e. increased flood events) and drier, warmer summers (i.e.extreme temperatures). These changes are likely to affect the inputs of contaminants into the environment as well as affect their behaviour, fate and transport, and toxicity in aquatic environments. It is known that the current temperature predictions in climate change scenarios could directly affect aquatic ecosystem communities (Carpenter et al., 1992), since temperature is also regarded as an important abiotic factor influencing growth and production of primary producers (i.e. algae, macrophytes etc.), and may also affect species distribution. For example, Liu et al. (2010) reported higher dissolution rates of AgNPs with increased temperature. Similarly, sudden hydrographic activity like high flood conditions may cause resuspension and redistribution of sediments. Few studies have linked the foreseeable climate change with contaminant release and ecosystem impacts. Similarly, few studies have analyzed the behaviour of NMs in the environment considering these predicted changes in mean temperatures. This thesis focuses on the effects of AgNPs on oxidative stress responses in the Cape River crab Potamonautes perlatus. The present work was undertaken to interpret the biological effects of AgNPs (< 100 nm) on P. perlatus, as well as to assess its effects under different environmental conditions. To understand the uptake, accumulation and biological effects of AgNPs, freshwater microcosms were produced to mimic a typical aquatic environment and temperature manipulated microcosms to which a commercially-available AgNP powder was added. Nanoparticles were characterized in the dry state and in suspension under different environmental conditions. Dissolution of total Ag was measured by inductively coupled plasma mass spectrometry (ICP-OES). Nanoparticle toxicity was assessed by measuring mortality and biomarkers of oxidative stress (CYP450, SOD, CAT, GST) evaluated in crab tissues. The overall results demonstrated that: (1) AgNPs may be transformed in both size and state under variable environmental conditions. The formation of smaller aggregates at higher temperatures suggests higher toxicity, (2) the release of free metal ions from NPs and NPs aggregates contribute to a higher toxicity towards aquatic organisms, (3) oxidative stress is a significant mechanism of AgNP toxicity and consequently enzymatic activation/inhibition with increasing AgNP concentration and temperatures, (4) oxidative stress responses to AgNPs particles were significantly modulated by temperature stress in P. perlatus, (5) mortality was observed from day 2 with maximum mortality achieved at day 7, (6) enzymes involved in detoxification, i.e. CYP450, has functional significance in the haemocytes, (7) P. perlatus has proved to be a significant target for AgNP exposure and, furthermore, has proved to be a suitable species to assess the ecotoxicity of AgNP in the aquatic environment, (8) antioxidant enzymes activities (are valuable tools to assess the oxidative status of crab tissues co-exposed to AgNPs and temperature. Furthermore, the results obtained in this study contributed to the understanding of the behaviour, bioavailability, uptake and toxicity of AgNPs under variable temperatures. / National Research Foundation (NRF) Thuthuka Fund and CSIR

As our knowledge of bivalves has increased, so has information about their parasites. Most studies of bivalve parasites have been devoted to groups infesting commercially important mollusks, notably trematodes and copepods. Another group of bivalve symbionts which has been known since the early nineteenth century is the brachyuran genus Pinnotheres Latreille, 1802 (commonly known as pea crabs). The generic name was given because of the belief that the crabs were predators upon the scallops in which they were most frequently found (Pearce, 1966). However, Stebbing (1893) suggested that instead of acting as predators, the crabs were in fact serving as guards for their hosts.

Various studies indicate the acmaeid limpet species Collisella digitalis, Collisella pelta and Notoacmea scutum inhabit different vertical zones in the rocky-intertidal region. At Sunset Bay, Oregon, Shotwell (1950) found that C. digitalis was situated in the upper intertidal C. pelta inhabited the mid-intertidal and N. scutum was located in the mid to lower zone in the rocky-intertidal region. Frank (1965) observed the same distribution patterns at Coos Bay, Oregon as did the author in the rocky-intertidal region near Dillon Beach, California. Species distributions in the rocky-intertidal region are thought to be limited from above by physical stress and from below by predation or competition (Connell 1970; Dayton 1971; Vermeij 1972; Paine 1974; Bertness 1977). The purpose of the present study was to investigate effects of the predators Pisaster ochraceus, Cancer antennarius and Pachygrapsus crassipes on the distributions of the three acmaeid limpet species particularly with respect to their lower limits.

Research in salt marshes dominated by the grass Sporobolus alterniflorus indicates that plant characteristics affect fiddler crab burrowing and in turn, crab activity can enhance primary productivity by increasing soil oxygen and nutrient cycling. Crab-plant interactions are less understood in microtidal Gulf Coast marshes compared to Atlantic Coast tidal marshes. It is unknown how structure of the dominant Gulf Coast vegetation zones (salt marsh, brackish marsh, fresh marsh and salt pannes) affects density of crab burrows and how burrows may influence primary productivity. I hypothesized that fiddler crabs would be most abundant in marsh zones with intermediate substrate hardness and vegetation density (Goldilocks Hypothesis). A seasonal habitat preference study was conducted during 2016-2017 in tidal marshes at Grand Bay National Estuarine Research Reserve in coastal Mississippi using burrow density as a proxy for crab abundance. Plant above- and below-ground biomass, burrow proximity to vegetation, and soil hardness were also surveyed as potential drivers of fiddler crab populations. The results indicated that fiddler crabs burrow in all four zones, but to varying degrees, and that burrow density was highest during autumn. The fresh marsh had the highest average density of burrows, as well as vegetation and soil parameters most representative of intermediate habitat, thereby supporting the “Goldilocks Hypothesis”. The brackish marsh also proved to be important fiddler crab habitat. Preferential fiddler crab usage of habitat upslope of salt marsh, e.g., fresh and brackish marsh, in Gulf Coast sites suggests that they may avoid immediate impacts of rising sea levels and possibly even migrate to higher ground if needed.

Hermit crabs form an important component of the marine benthos and globally more than 1,200 species have been described. In the unique bioregion of South Africa, hermit crabs are poorly known, and the last taxonomic revision of the group was that of K. H. Barnard in 1950, who recorded only 32 species. This study combines morphological taxonomy, threedimensional (3D) micro-computed tomography (µCT) visualisations, and molecular barcoding to add to, revise, and provide an updated listing of, the regional fauna. The first section of the thesis comprises four chapters, each giving a detailed account of a species either new to science, or to the region. The pagurid hermit crab Goreopagurus poorei, a new species and genus record to the country, is reported and described from deep sea habitats along the Agulhas Shelf, extending the distribution by >10,000 km across the Indian Ocean. Furthermore, three species are described as new to science, one each from the three most common families. The first of these, a deep-water species from a genus of the family Parapaguridae that was previously unknown to South Africa, Paragiopagurus atkinsonae n. sp., is fully described and illustrated, and compared with two other parapagurids that each play a dominant role in the regional benthic offshore invertebrate community. The other two species new to science, Diogenes n. sp. from the family Diogenidae, and Pagurus n. sp. from the family Paguridae, inhabit coastal reefs in subtidal waters off southern KwaZulu-Natal. For the first time in crustacean taxonomy, species descriptions, particularly the one of Pagurus n. sp., are informed by, or based on, µCT imagery of calcified body parts. Following on this technique, Chapter 6 is a short presentation of the 3D raw dataset of seven µCT scans of types and rare museum specimens used in this thesis, which is made publicly available for download. The taxonomic use of the scanning method, with disseminating volumetric data of hermit crabs, is discussed briefly. The final section investigates the fauna as a whole. In Chapter 7, 194 cytochrome c oxidase subunit I gene segments (COI ‘barcodes’) of 43 nominal species plus 12 additional putative species (n = 55 species-like units) were used to validate morphological identifications. Testing this dataset revealed high barcoding efficacy, with nearly 99% identification success rates, and with the best Kimura 2-parameter distance to safely delimit species of hermit crabs of about 3.5%. Chapter 8 updates the regional fauna and provides taxonomic accounts for 62 nominal species which have either been added subsequent to the previous monographic review, or which have undergone taxonomic revision since that time. Of these, 12 are added for the first time here, increasing the number of known South African hermit crab species to 72, an expansion of 56% since Barnard, and about 20% since a recent species list published by W. Emmerson in 2016. Because colour images are provided for 51 out of 72 species, Chapter 8 can also be used as a preliminary guide. However, this study has shown that the hermit crabs of South Africa are by far more diverse than originally thought, and the summary, which includes only the 72 nominal taxa and none of the additional 10 putative species included in the barcoding dataset, is speculated to be only 60–70% complete. Future taxonomic work, especially in the genera Diogenes and Paguristes, will most likely result in many more species descriptions. Therefore, this current study is to be seen as important step towards a fully illustrated taxonomic catalogue on the South African hermit crabs to be produced in the near future.