A two part project spanning four and one half years was designed to investigate a number of aspects of the natural history of Octopus dofleini in the Northeast Pacific. The tag-release recapture (Part I) involved weekly SCUBA dives, during daylight hours, at three sites on Southern Vancouver Island, British Columbia, Canada. A total of 320 octopuses were sighted during 616 dives (Part I) and 151 of those octopuses were tagged or recaptured. The ratio of dives per octopus sighted was 1.93:1 and the ratio of dives per octopus tagged or recaptured was 4.08:1. A total of 98 octopuses were tagged (Part I) and 30 of those octopuses were recaptured two or more times for a recapture rate of 30.61%. Statistical analysis of data weighted to provide uniform effort showed Site 1 (Tanner Rock) to have a significantly greater number of large octopuses while Site 2 (Tozier Rock) had a significantly greater number of very small octopuses. An analysis of the data on octopus sex ratios found no significant difference between the number of males and females at each site even though there had been a significant difference in the ratio within Site 2. Analysis of data on annual distribution of octopus body weight combined with the results from the recapture of individual octopuses led to the proposal of a four year lifespan for female Octopus dofleini and an undetermined, but longer, lifespan for males of the species. An examination of the data on octopus movement showed that a peak number of small octopuses (approximately 250 g) appeared at the sites in February. The evidence showed that over the next 19 to 22 months the octopuses grew from approximately 250 grams to a pre adult body weight of 13.8 kg for males (in September) and 14.7 kg for females (in December). No octopuses between 16 and 19.5 kg were captured suggesting a movement of octopuses of that body weight away from the sites. Small numbers of octopuses weighing between 19.5 kg and 28 kg were captured mainly during the first half of the year. An analysis of octopus position data showed that Octopus dofleini does not maintain a constant distance from its nearest neighbour. Nearest neighbour distance was not significantly influenced by the size or sex of the neighbour nor by changes in water temperature. A highly significant correlation was found between estimated den volume and octopus body weight. There were no significant relationships between den surroundings, number of exits, den type and den depth when compared to den usage suggesting that Octopus dofleini is an opportunistic animal using whatever shelter of appropriate volume it discovers. The major food item at all sites as determined by midden heap contents was the Red Rock Crab, Cancer productus. An examination of the physical condition of each octopus captured revealed 21.2% of the animals had either scars or amputated arms or both. Correlations examining the relationships between water temperature and growth rate, body weight, sex and nearest neighbour distance were nonsignificant. Part 11 of the project was the physical measuring and describing of each den at each site. During the 126 SCUBA dives done another 127 octopuses were sighted. As octopuses were captured only when it was necessary to examine the inside of the den there were only 11 octopuses captured during the second part of the project. In total, 447 octopuses were sighted during 742 dives. This results in an effort per octopus sighted of 1.66 dives per octopus. / Graduate

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19530号 / 理博第4190号 / 新制||理||1601(附属図書館) / 32566 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 朝倉 彰講師宮崎 勝己, 教授 曽田 貞滋 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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Information regarding spawning site fidelity and movement patterns of the American horseshoe crab (Limulus polyphemus) is crucial for developing effective conservation and management strategies on the correct spatial scale. To investigate the spatial ecology of American horseshoe crabs, 75 adult animals were tracked off the coast of Chatham, Cape Cod, MA from June 2010 to November 2011 using acoustic telemetry. Two groups of horseshoe crabs were tagged in spawning habitats (separated by ~2.0 km) with differing commercial harvesting pressure: one group inside Stage Harbor, where harvesting is permitted and the other within a Marine Protected Area (MPA) where harvesting is prohibited. Network analysis revealed that horseshoe crabs exhibited fidelity to spawning habitat, but not necessarily to the habitat where they were initially tagged. Fifty-nine percent of horseshoe crabs tagged inside Stage Harbor were detected in the MPA and 13% of horseshoe crabs tagged in the MPA were detected inside Stage Harbor. Although horseshoe crabs were utilizing both spawning habitats, predictive modeling revealed little temporal overlap, suggesting that horseshoe crabs from the two spawning habitats represent local populations. Isolated and local populations are more susceptible to overexploitation than are larger populations with many migrants. To protect against overharvest and extinction of isolated and local populations, the correct identification of management units (MUs) must be a priority of fisheries managers. Horseshoe crab populations around Cape Cod, Massachusetts and New England behave differently, requiring the collection of more information so that conservation tools such as MUs or MPAs can be used most effectively.

Changes in abundance of interactive species can have cascading, community-wide effects (Soule et al. 2003). Raccoons (Procyon lotor) prey on a competitor for marine turtle eggs, the Atlantic ghost crab (Ocypode quadrata). Conservation of marine turtles often includes managing raccoons-the most obvious egg predator-which may have broader ecological effects, and unknown effects on egg predation. Neither the relationship between raccoons and ghost crab density nor the effects of ghost crab density on egg predation are well understood. I studied raccoon-ghost crab interactions and the effects of environmental variation on their activity during the 2007 marine turtle nesting season on Canaveral National Seashore, FL. My goal was to model predator activity and identify efficient management strategies to reduce egg predation. Raccoon activity increased with increasing habitat diversity and edge of the dominant cover type, coastal strand. Raccoon activity increased locally and became less variable near segments of beach accessed for human recreation, but activity was greater on undeveloped beach, where habitat diversity and edge were greater. Ghost crab density and size were primarily affected by sand characteristics and recreation but decreased with increasing raccoon activity in June, which may have contributed to sustained declines in ghost crab density. Hatching success of marine turtles decreased with increasing ghost crab egg predation, suggesting ghost crabs are an important cause of egg mortality and not merely scavengers on unhatched eggs. Egg predation by ghost crabs was unrelated to ghost crab density or size, likely a result of monitoring limitations, but raccoon activity increased with increasing egg predation by ghost crabs, supporting previous research and experimental evidence suggesting ghost crabs can facilitate secondary nest predation by raccoons. This indirect interaction has strong implications for marine turtle conservation, because its strength may increase with increasing ghost crab density, potentially negating the effects of raccoon removal.

Wastewater from the pressure cooking of blue crabs presents a difficult treatment challenge. COD concentrations in the range of 15,000 to 30,000 mg/L are found in this wastewater, with TKN concentrations above 2,000 mg/L. Direct discharge of the wastewater, which is currently allowed, adds nutrients to the Chesapeake Bay, and potentially creates local DO depletion in receiving waters. Anaerobic treatment of this wastewater was studied for the reduction of COD. Nitrification was studied for the conversion of ammonia, present at levels above 1,000 mg/L NH3/NHA4-N, to nitrate for possible denitrification. COD reductions averaging above 11,000 mg/L were found to occur in an upflow anaerobic filter operating with less than a 4 day HRT. Further COD reduction in the aerobic reactor resulted in a final effluent averaging 2,400 to 3,100 mg/L soluble COD with a corresponding BOD₅ of 110 to 340 mg/L. Nitrification proved to be inhibited, perhaps by the high levels of NH₃/NH₄-N in the effluent from the anaerobic stage. Nitrification did occur in a batch study, but only after extended aeration, and depletion of BOD. Non-degradable COD was estimated to be 2,900 mg/L in the anaerobic effluent. Monod model kinetic coefficients for the anaerobic stage were determined on a degradable COD basis to be: k = 0.68 day⁻¹, Ks = 3,500 mg/L (degradable portion), Y = 0.19, and Kd = 0.028 day⁻¹. The effect of the addition of certain trace metals (Fe, Ni, Co, Mo) to the feed was investigated. There was no improvement in COD removal performance, and slight inhibition may have occurred. / Master of Science

The freshwater crab fauna of Vietnam has a high diversity and endemism, 49 species have been recorded and 42 of them are only known from this country. In addition, many species are undescribed or undiscovered while at least 10% of known species are facing extinction. Water pollution, urban, industrial and agricultural development, habitat loss and fragmentation, deforestation and overexploitation are the main threats to this fauna. The first conservation recommendation is keeping rain forest tracts large enough to maintain habitat and water quality for long-term survival of these crabs. More research on taxonomy, distribution, population dynamics, main pressures, conservation status are needed in order to assess conservation status and create efficient conservation actions for freshwater crabs in Vietnam. / Khu hệ cua nước ngọt ở Việt Nam có mức độ đa dạng và đặc hữu cao với 49 loài đã được ghi nhận, trong đó có tới 42 loài chỉ được biết đến ở Việt Nam. Ngoài ra, nhiều loài cua nước ngọt còn chưa được mô tả hay chưa được khám phá, trong khi có tới 10% trong tổng số loài đã biết đang phải đối mặt với nguy cơ tuyệt chủng. Ô nhiễm môi trường nước, đô thị hóa, phát triển công nghiệp và nông nghiệp, nơi sống bị phân mảnh và mất, phá rừng cùng với khai thác quá mức là những mối đe dọa chính đối với khu hệ này. Công tác bảo tồn trước hết phải giữ cho diện tích rừng đủ lớn để duy trì chất lượng môi trường sống cho sự tồn tại lâu dài của các loài cua này. Các nghiên cứu về phân loại học, phân bố, động lực quần thể là rất cần thiết để đánh giá tình trạng bảo tồn và đưa ra những hành động bảo tồn hiệu quả cho các loài cua nước ngọt ở Việt Nam.

Microplastics are widespread and abundant. Few studies have examined the diversity and abundance of microplastics in wild organisms. This study determined the microplastic quantity and types in the organic tissues of the eastern oyster Crassostrea virginica and Atlantic mud crab Panopeus herbstii from the Indian River Lagoon (IRL). This study also investigated whether location affected the microplastic abundance and variety. Organisms were collected from three sites across Mosquito Lagoon in the northern IRL. Oysters were frozen after collection. Crabs were placed in containers for 5 days before freezing. The soft organic tissue was chemically digested using hydrogen peroxide, filtered, and examined for microplastics. Water samples collected from each study site had an average of 23.1 microplastic pieces per liter and fibers were the most common type. There was a significant interaction for microplastic type and site for both oysters and crabs (p

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