Crustacean spermatozoa are among the most peculiarly modified germ cells in the animal kingdom. Many of their striking cytological specializations may be observed in the sperm cells or Emerita analoga, the so-called sand crab. This animal has been used by the writer for studies on spermatogenesis and on spermatozoan behavior during the summer or 1951, 1952, and 1953 at the Pacific Marine Station.

No description available.

The purpose of this research was to determine the feasibility of pasteurizing crabmeat in retort pouches compared to cans. Retort pouches and cans were packed with various amounts of crabmeat, pasteurized to an internal temperature of 185°F (85°C) for 1 min, and subsequently cooled. The criteria for evaluation were total processing time, process lethality (F value), microbiological stability and sensory evaluation. Pasteurizing crabmeat in retort pouches resulted in total processing times that were significantly less (P ≥ 0.05) than cans. Also, pasteurizing to targeted F values provided a more rapid and efficient way to achieve equivalent processes. Thus, equivalent can processes were given to pouches in significantly less (P ≥ 0.05) time. Microbial loads were reduced by greater than 99% in both pouches and 65 cans following pasteurization to a target F value (F⁶⁵₁₈₅ = 24). This reduction was maintained during 6 months storage at 36°F (2.2°C). Sensory evaluations conducted over a 6 month period indicated no real preference for crabmeat packaged in retort pouches or cans. However, crabmeat packed in pouches was significantly better (P ≥ 0.05) on some weeks. Hedonic scores indicated meat in both types of containers were acceptable for the duration of the study. It was concluded that packaging and pasteurizing crabmeat in retort pouches is an acceptable, if not superior, method of pasteurization. / Master of Science

The ability of prey to detect and respond appropriately to predator risk is important to overall prey fitness. Many aquatic organisms assess risk through the use of chemical cues that can change with predator diet. Two variable characteristics of diet are: 1. prey type and 2. prey mass. To assess the effect of these two characteristics on the assessment of risk by the mud crab Panopeus herbstii, I exposed mud crabs to the urine of the blue crab Callinectes sapidus fed one of 5 diet treatments: 10g of oyster shell free wet mass, 5g of oyster shell free wet mass, 10g crushed mud crabs, 5g crushed mud crabs, and a mix of 5g of oyster shell free wet mass and 5g crushed mud crab. Effects on P. herbstii foraging were tested in a previously developed bioassay by measuring shrimp consumption over a 4 hour period. I hypothesized that P. herbstii would have a larger magnitude response to urine from C. sapidus fed a diet of crushed mud crabs than to urine from C. sapidus fed a diet of oysters. I further hypothesized that P. herbstii would have a larger magnitude response to urine from C. sapidus fed a high mass diet relative to a lower mass diet. Contrary to expectations there was no observed effect of urine on P. herbstii foraging in any of the treatments. Results suggest that bioassay protocol may be unreliable suggesting further replication to determine the difference between this study and previous results. Future studies examining how P. herbstii varies with urine concentration will aid in understanding the ecological scale of this predator cue system. Determining the role of other potential cue sources will improve the predictive abilities of these studies.

No description available.

Juvenile male blue crabs move into the tidal, freshwater James River during warmer months to feed and grow by undergoing molting. In crustaceans, growth and molting are hormonally controlled. The physiological effects of a multiple-stressor environment are determined by comparing the blue crab’s oxygen uptake after exposure to pure sand, James River sediment, or endosulfan-spiked sand. The effect of multiple stressors on molting is measured by the activity level of N-acetyl-ß-glucosaminidase (NAG), an enzyme in epidermal tissue important to molting. The oxygen uptake was decreased by exposure to James River sediment but not for exposure to endosulfan for seven days. Exposure to James River sediments over two days caused a similar suppression of epidermal NAG activity as exposure to endosulfan. These results indicate that the blue crab’s exposure to James River sediments and moderate hypoxia has the potential to cause short-term effects on physiology and long-term effects on growth.

With the different threats sea turtles are currently facing, such as habitat reduction and pollution, increase of fishing and harvesting of aquatic resources by Humans, or invasive species, it is important to learn as much as possible about their biology and behaviour in order to ensure the success of conservation programs. In this study, loggerhead sea turtles (Caretta caretta) feeding behaviour duration as well as energy expenditure approximation during a feeding event were tested and compared using two different types of food: green shore crabs (Carcinus maenas) or Japanese clam (Ruditapes phillipinarum) or Venus clams (Chamelea gallina). The data show that the turtles took longer to approach the crabs but took more time to eat the clams. However, comparison of energy expenditure values for the feeding phase showed no significant differences. The turtles were observed to eat the clams’ shell as well as their meat. These shells are rich in calcium, which is one possible explanation for this behaviour. This study shows that data loggers represent a viable tool for studying the behaviours of marine animals.

Kingsleyini corresponde a uma das cinco tribos de Pseudothelphusidae, grupo exclusivamente americano de caranguejos de água doce. Atualmente a tribo inclui 59 espécies agrupadas em 13 gêneros, com distribuição associada aos rios, riachos e igarapés das bacias do Amazonas e do Orinoco. Desde a criação de Kingsleyini o aumento de novos táxons atribuídos a esta tribo não tem sido acompanhado por estudos cladísticos. No presente trabalho é realizada a análise cladística de Kingsleyini, acompanhada de uma revisão morfológica e taxonômica do grupo. Com este propósito, foram estudados espécimes de 60 espécies representantes das cinco tribos e duas subfamílias inclusas em Pseudothelphusidae. O material estudado se encontra depositado nas coleções carcinológicas de seis instituições e inclui os tipos nominais de 29 espécies. Na revisão morfológica foram descritas e ilustradas estruturas somáticas e sexuais da morfologia externa do grupo de estudo. Os estudos morfológicos foram auxiliados por técnicas de Microscopia Electrônica de Varredura (MEV) e cortes histológicos. A partir destas observações foram propostas modificações na terminologia utilizada para denominar as estruturas do primeiro apêndice sexual masculino (primeiro gonópodo) em Kingsleyini. A parte taxonômica deste trabalho inclui chaves de identificação, mapas de distribuição, listas sinonímicas e a descrição e ilustração do primeiro apêndice sexual masculino para a grande maioria das espécies examinadas, assim como a diagnose dos gêneros considerados monofiléticos. A análise filogenética foi realizada a partir de 92 caracteres obtidos de 57 táxons terminais: 49 terminais do grupo interno (Kingsleyini) e oito do grupo-externo (representantes dos demais Pseudothelphusidae). Como resultado da análise cladística foram obtidas seis hipóteses filogenéticas igualmente parcimoniosas: todas elas apoiam o monofiletismo de Kingsleyini e a exclusão do gênero Spirocarcinus da tribo. O monofiletismo dos gêneros Fredius, Kingsleya, Eudaniela e Rodriguezus também encontra-se sustentado em todas as hipóteses filogenéticas obtidas, enquanto que os gêneros Microthelphusa, Neopseudothelphusa, Orthothelphusa e Brasiliothelphusa revelaram-se parafiléticos. / Kingsleyini is one of the five tribes of Pseduthelphusidae, a American freshwater crabs family. Hitherto, this tribe includes 59 species and 13 genera with distribution associated to creeks and rivers of the Amazon and Orinoco basins. Since the establishment of Kingsleyini, the increase of new taxa attributed to the tribe has not been followed by cladistics studies. In this study, a phylogenetic analysis of Kingsleyini is provided, along with a morphological and taxonomic revision. With this aim, specimens of 60 species belonging the five tribes and two subfamilies comprising Pseudothelphusidae were studied. The specimens studied are housed in the carcinological collections of six institutions and included the nominal types of 29 species. In the morphological revision, somatic and sexual structures of external morphology were described and illustrated. Morphological studies were aided with Scanning Electron Microscope (SEM) techniques and histological sections. Based on these observations, some changes in the terminology of the first gonopod of Kingsleyini are proposed. The taxonomic part includes identification keys, distribution maps, synonymy lists, and descriptions and illustrations of the first gonopod for most species studied; along with diagnose for the genera considered monophyletic. For the phylogenetic analyses, 92 morphological characters were examinated for 57 taxa terminals: 49 ingroup (Kingsleyini) and eight outgroup (others pseudothelphusids). Six phylogenetic hypotheses equally parsimonious were retrieved: all supporting the monophyly of Kingsleyini, and the exclusion of Spirocarcinus of the tribe. The genera Fredius, Kingsleya, Eudaniela and Rodriguezus were supported as monophyletic groups, while Microthelphusa, Neopseudothelphusa, Orthotheplhusa and Brasiliothelphusa were retrieved as paraphyletic groups.

The hermit crab Clibanarius vittatus kills Melongena corona solely to acquire a better fitting shell. This finding is contrary to previous studies, which found that hermit crabs of other species cannot kill gastropods or, in most instances, remove freshly dead gastropods from their shells. This interaction cannot be classified as predation because Melongena tissue was never consumed. Clibanarius killed Melongena only when by doing so they could trade up to a better fitting shell. It cannot be classified as competition because there is no opportunity for Melongena to gain from the interaction. Therefore the term “lethal eviction” is hereby proposed for this interaction. The ability to kill a gastropod to obtain a superior shell gives Clibanarius vittatus an evolutionary advantage over other hermit crab species. It is not known if the outcome of this interaction is widespread where both species occur or if it is confined to the study area. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2007 / Urban rivers are the most utilised and yet degraded rivers worldwide. The urban rivers of the Western Cape are no different. The Lourens River flows through the agricultural and urban areas of Somerset West in the Western Cape and as a result is subjected to a variety of pollution sources. In the upper reaches this river flows through two large farms where metal containing pesticides are used. Further downstream it passes through an urban area where a variety of pollution sources could contribute to the contamination of the river. The extent to which the Lourens River, and the ecosystem it supports, is affected by metal pollutants is not known. The aim of this study was to determine the concentrations of metals in the Lourens River as well as the contribution of agricultural and urban activities to metal contamination of the river. Sediment and crab (Potamonautes perlatus) samples were collected over a period of one year from seven sites over the length of the river. Sediment samples were also collected from a sedimentation pond on the bank of the river where orchard run-off water is remediated. Preliminary analysis of samples was done for ten metals (AI, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb and Zn). Results from these analyses determined the selection of six metals (AI, Cr, Cu, Fe, Mn and Zn) for further investigation in this study. The concentrations of metals detected in collected samples varied significantly throughout the sampling period. This can be attributed to various factors such as rainfall patterns, the fact that pesticide application varies throughout the year and other urban activities. AI, Cr, Fe and Zn were found in significantly higher concentrations in the urban areas. These higher levels of contamination, relative to the upper parts of the river, can probably be attributed to various urban activities contributing to the contamination of run-off into the river. The sedimentation pond results revealed high concentrations of AI and Fe, while Cu, Cr, Mn, and Zn were found in lower concentrations. All six metals however followed the same pattern where the first four sampling occasions showed higher concentrations than the last three occasions. It can be concluded that agricultural and urban activities do contribute significantly to the metal contamination of the Lourens River.