Crabs of the species Hemigrapsus oregonensis, when held at temperatures of 5° and 18°C for eight days and then observed at temperatures approximating these holding conditions and at intermediate temperatures, showed greatest locomotor activity and frequency of behaviour patterns at highest temperature conditions. At intermediate temperatures, locomotor activity was greater in crabs from the higher holding condition, and the greatest variability was recorded for females at an observation temperature of 19°C. Observations made at 0530, 1030, 1630 and 2230 hours of the day showed that a peak activity period occurred at 0530 hours in male crabs at most temperature conditions. This may have been caused by the low intensity of illumination used at night. Presentation of chemical food stimuli in the form of a solution of liver to crabs, elicited feeding and probing movements and an increase in locomotor activity. Pieces of art eraser simulating tactile stimuli of meat elicited feeding movements, but no response could be shown to sight of sculpins or minced liver. Visual stimuli appeared ineffective even when combined with other stimuli. Combinations of chemical and tactile stimuli, however, appeared to sum, and responses were increased above those obtained by separate presentation. Starvation increased the frequency of all behavior that occurred as a response to food stimuli. / Science, Faculty of / Zoology, Department of / Graduate

Organismal tolerance to abiotic environmental stresses contributes significantly to setting the distribution limits of organisms, as demonstrated by vertical zonation patterns in the marine intertidal zone. In this thesis, the ultimate (evolutionary) and proximate (mechanistic) causes of tolerance to temperature and emersion stresses associated with the intertidal zone were examined using porcelain crabs, genus Petrolisthes. Species of Petrolisthes from intertidal and subtidal microhabitats of four biogeographic regions of the Eastern Pacific were used in phylogenetically-based comparative analyses of morphological, physiological, and biochemical adaptation to environmental stress. A phylogenetic tree based on the sequence of the 16sRNA gene was developed to facilitate these analyses. Organismal thermal tolerance limits are adapted to match maximal microhabitat temperatures. Acclimation of thermal tolerance limits suggests that temperate intertidal zone species are living close to their thermal maximum in nature. Respiratory responses to emersion vary among species from different vertical zones. Experimental examination of oxygen consumption rates and lactate accumulation during emersion suggests that intertidal species are able to respire in air using thin membranous regions on the ventral meral segments of their legs (leg membranes). Leg membrane size is positively correlated with body size across species, but not within a single species. Evolutionary analyses indicate that leg membranes may not have evolved for purposes of aerial respiration, but their presence may have allowed intertidal and subtidal species to achieve larger body sizes and higher metabolic rates. The thermal stabilities of an enzyme, lactate dehydrogenase (LDH), from 22 species of Petrolisthes varied widely, but were not correlated with maximal habitat temperatures. Comparative analyses did not indicate any evolutionary relationship between LDH thermal stability and microhabitat conditions. Experimental evidence suggests that interspecific differences in LDH stability are genetically based, and are due both to intrinsic properties of the LDH molecules and extrinsic protein stabilizers. Elucidation of the mechanism(s) of LDH stabilization in Petrolisthes may provide novel insight to the field of protein stabilization. These results studies suggest that individual traits may be subjected to differing levels of selection, and thus the analysis of environmental adaptation requires careful consideration of the biological significance of the traits being examined. / Graduation date: 1999

Thesis (Ph.D.) - James Cook University, 2002. / Typescript (photocopy) Bibliography: leaves 145-156.

Thesis (Ph. D.)--James Cook University, 2002. / Includes bibliographical references (leaves 145-156).

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Eleven cruises were conducted on the Oregon continental slope from April 1973 to March 1975 to assess the biology and ecology of the Tanner crab, Chionoecetes tanneri Rathbun. Bathymetric and seasonal analysis of the distribution of adult Tanner crabs west of Coos Bay, Oregon, revealed no segregation of sexes or seasonal migration. Relative abundance of adult crabs was greatest in the 500-700m depth range. Juveniles were found throughout the adult depth range. Density estimates using a three meter beam trawl were 0-500 crabs/km² (mean = 56) for adult male C. tanneri and 0-1100 crabs/km² (mean = 164) for adult females. Stock estimates for the Oregon coast (500- 700m) and for the Oregon and Washington coasts (457-869m) supported Pereyra's (1972) conclusion that a Tanner crab fishery would not be feasible at this time. Longline pot fishing was suggested as a better method of assessing the commercial potential of the Tanner crab stock. Hydrological and sediment data indicated that the Tanner crab environment is a relatively stable one temporally and spatially in the study area. There was no apparent relationship between the presence or absence of adult C. tanneri and temperature, salinity, dissolved oxygen, sediment organic carbon content, or sediment particle size. / Graduation date: 1976

During eleven cruises conducted off the Oregon continental slope from April 1973 to March 1975, approximately 1600 specimens of the majid crab Chionoecetes tanneri Rathbun were collected. A time sequence of size frequency histograms and bivariate plots of allometric measurements were used to determine size classes, population structure, growth and age at maturity of C. tanneri from the Oregon coast. Adult sex ratios and sex ratios for each of the juvenile size classes were computed. Bivariate plots of carapace width and cheliped length for males and carapace width and abdomen width for females defined nine size classes for juvenile males and eight size classes for juvenile females. The morphogenic relationship between differential cheliped length and gonad maturity in males and differential abdomen width and gonad maturity in females (Watson, l970a; Brown and Powell, 1972) allowed determination of minimum size at maturity of 118 mm carapace width for male C. tanneri and 85 mm carapace width for female C. tanneri. Mean carapace widths for adult males (142.7 mm) and adult females (102.5 mm) collected for this study compare well with those given by Pereyra (1972). Mean carapace width increase for each molt for all juvenile size classes was computed to be 26.14%. When size classes were equated to molt groups a linear regression (Time = -2.94 + 0.81 (Carapace width)), based on progression of carapace width modes through time, predicts age at maturity to be from five to six years. A highly significant departure from a 1:1 sex ratio for adults, of 2.41 females per 1 male, is consistent with reports for other members of the genus Chionoecetes (Hilsinger, 1975). / Graduation date: 1976

Thesis (Ph. D.)--University of Hong Kong, 1983.

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

No description available.