The microdistribution of the amphipod Eohaustorius brevicuspis was examined over a 19 month period. Field sampling was conducted principally at Lost Creek State Park, Oregon, and on one occasion at Driftwood State Park, Oregon. Both are high-energy, fine sand beaches which appear to be uniform. Stratified random samples were taken with each of a series of corers of varying diameters. For the samples obtained for each size of corer, indices of dispersion were calculated and evaluated to obtain information on the size of patches, the distribution of individuals within patches, and the distribution of the patches. E. brevicuspis from Lost Creek at natural densities were placed in a box of thoroughly sieved, well-mixed sand in the laboratory, together with natural densities of other macrofauna, or with other macrofauna excluded. The positions of individuals in the box were determined by partitioning the Sand into 192 blocks (2 cm by 2 cm) horizontally, and into 3 layers (6.6 cm deep) vertically. In two of five experiments, the length and sex of every individual were also recorded Additional experiments were conducted to examine the predation rate of the isopod Cirolana harfordi on E. brevicuspis, to test for endogenous tidal periodicity in the depth in the sand at which E. brevicuspis is found, and to determine the direction of burrowing during downward migration. Patches of higher density were variable in size, but occurred most frequently with diameters near 15 cm. In the field, larger-scale patches with diameters of two meters were also found In laboratory experiments, the number of individuals per patch and the number of patches varied with the overall density. Patches were surrounded by low-density areas containing from 1/4 to 1/10 as many individuals per unit area. Individuals within patches tended to be spaced uniformly. It was not possible to determine the distribution of patches. Patches were formed in the laboratory in the absence of predators, other macrofauna, and observable environmental heterogeneity. They appear to be present at all times, although downward migration at low tide and upward migration at high tide was indicated. Over six hours, an artifically created patch of dyed amphipods migrated downward but did not spread horizontally, suggesting that individual patches could remain intact through one or more tidal cycles. There was no segregation of different sexes or sizes into different patches, although smaller individuals tended to be located nearer the surface of the sand. Patchiness is this species is probably not caused by responses to physical environmental heterogeneity, or to other macrofauna (including both predators and competitors), nor by behavior associated with reproduction. Some possible consequences of the observed distribution of this species were discussed. / Graduation date: 1979

Two separate studies on the distribution of gammarid amphipods in the bathyal and abyssal benthic environments demonstrated that different assemblages could be found at a single depth over distances on the order of 100 kilometers. These studies evaluated changes in the species composition and relative abundance of the amphipod assemblage utilizing samples collected with an epibenthic sled. The amphipod faunas of the San Diego Trough and Tanner Basin were compared utilizing 18 epibenthic sled hauls. These two bathyal basins of the Continental Borderland off Southern California are very similar in their environments and both have a bottom depth close to 1250 meters. The amphipod fauna from each basin was characterized by comparing the percentage each species comprised of the total amphipod fauna, the frequency of occurrence of each species, and the rank order of abundance of species. The large differences observed in the structure of the amphipod assemblage between the two basins can probably be attributed to different sources of food in the two basins. Nineteen sled hauls were collected at two stations on Cascadia Abyssal Plain located off the Oregon coast at 2800 meters depth. The two stations were representative of the near shore and offshore portions of this abyssal plain. The amphipod assemblages were found to be very different at these two stations, despite their similar depths and physical environments. Geological evidence indicated that the sources of food to the sea floor at these two stations were likely to be very different. It was this difference in food input that seemed most likely to be the cause of the faunal difference. These studies of "mesoscale" zoogeography have added a new element of complexity to our understanding of factors controlling animal distributions in the deep sea benthos, because they have demonstrated that different assemblages can be found at the same depth in the same geographic region. The results suggest that the quality and quantity of food supplied to the deep sea floor may play a major role in controlling the composition of the fauna. / Graduation date: 1977

Thesis (Ph. D.)--University of Michigan, 1968. / Research supported by Federal Water Pollution Control Administration Grant WP-00311 and National Science Foundation Grant GA-1337. Includes bibliographical references.

by Kwok-ho Tsoi. / Thesis submitted in: October, 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 208-222). / Abstracts in English and Chinese. / Abstract --- p.1 / Acknowledgments --- p.5 / Contents --- p.6 / List of Figures --- p.10 / List of Tables --- p.15 / Chapter Chapter 1. --- Introduction --- p.16 / Chapter 1.1 --- Literature Review --- p.16 / Chapter 1.1.1 --- Biology of Amphipods --- p.16 / Chapter 1.1.1.1 --- External Morphology --- p.16 / Chapter 1.1.1.2 --- Habitat --- p.19 / Chapter 1.1.1.3 --- Feeding Habit --- p.20 / Chapter 1.1.1.4 --- Reproductive Biology --- p.22 / Chapter 1.1.2 --- The Application of Amphipods in Environmental Bioassays --- p.25 / Chapter 1.1.2.1 --- Abundance and Availability --- p.26 / Chapter 1.1.2.2 --- Sensitivity --- p.26 / Chapter 1.1.2.3 --- Ecological Relevance --- p.27 / Chapter 1.1.2.4 --- Living Habit --- p.28 / Chapter 1.1.2.5 --- Sublethal Response --- p.29 / Chapter 1.2 --- Objectives of this Study --- p.30 / Chapter Chapter 2. --- Taxonomic Identification of Hyale sp --- p.32 / Chapter 2.1 --- Introduction --- p.32 / Chapter 2.2 --- Materials and Methods --- p.33 / Chapter 2.2.1 --- Collection of Amphipods --- p.33 / Chapter 2.2.2 --- Preservation and Anesthesia --- p.35 / Chapter 2.2.2.1 --- Preservation --- p.35 / Chapter 2.2.2.2 --- Anesthesia --- p.35 / Chapter 2.2.3 --- Dissection --- p.35 / Chapter 2.2.3.1 --- Dissecting Instruments --- p.35 / Chapter 2.2.3.2 --- Dissecting Medium --- p.35 / Chapter 2.2.3.3 --- Photographic Recording and Illustration --- p.36 / Chapter 2.3 --- Results --- p.36 / Chapter 2.3.1 --- Figure Index --- p.36 / Chapter 2.3.2 --- Description of Key Characters --- p.40 / Chapter Chapter 3. --- Growth of Hyale sp --- p.60 / Chapter 3.1 --- Introduction --- p.60 / Chapter 3.2 --- Materials and Methods --- p.62 / Chapter 3.2.1 --- Growth in Standardized Environmental Conditions --- p.62 / Chapter 3.2.1.1 --- Experimental Animals --- p.62 / Chapter 3.2.1.2 --- Culture Conditions --- p.62 / Chapter 3.2.1.3 --- Examination and Recording --- p.64 / Chapter 3.2.2 --- Growth of Juveniles in Different Salinities --- p.67 / Chapter 3.2.2.1 --- Experimental Animals --- p.67 / Chapter 3.2.2.2 --- Culture Conditions --- p.67 / Chapter 3.2.2.3 --- Examinations and Recording --- p.68 / Chapter 3.2.3 --- Morphometric Analysis on Length - Weight Relationship --- p.69 / Chapter 3.2.4 --- Statistical Analysis --- p.69 / Chapter 3.3 --- Results --- p.69 / Chapter 3.3.1 --- Growth in Environmental Conditions --- p.69 / Chapter 3.3.1.1 --- Life Span --- p.69 / Chapter 3.3.1.2 --- Molt Cycle --- p.71 / Chapter 3.3.1.2.1 --- Age --- p.71 / Chapter 3.3.1.2.2 --- Intermolt Duration --- p.71 / Chapter 3.3.1.3 --- Body Length (BL) --- p.76 / Chapter 3.3.1.4 --- Head Length (HL) --- p.80 / Chapter 3.3.1.5 --- Eye Length (EL) --- p.33 / Chapter 3.3.1.6 --- Length and Articles of Antenna 1 (AL1 & AA1) --- p.86 / Chapter 3.3.1.7 --- Length and Articles of Antenna 2 (AL2 &AA2) --- p.90 / Chapter 3.3.1.8 --- Propodus Length of Gnathopod 1 (GL1) --- p.97 / Chapter 3.3.1.9 --- Propodus Length of Gnathopod 2 (GL2) --- p.103 / Chapter 3.3.1.10 --- Merus Length of Pereopod 7 (MP7) --- p.110 / Chapter 3.3.2 --- Growth of Juveniles in Different Salinities --- p.114 / Chapter 3.3.2.1 --- Survival Rate --- p.114 / Chapter 3.3.2.2 --- Age --- p.117 / Chapter 3.3.2.3 --- Intermolt Duration --- p.117 / Chapter 3.3.2.4 --- Body Length (BL) --- p.117 / Chapter 3.3.2.5 --- Head Length (HL) --- p.121 / Chapter 3.3.2.6 --- Eye Length (EL) --- p.121 / Chapter 3.3.2.7 --- Length of Antenna 1 (AL1) --- p.124 / Chapter 3.3.2.8 --- Number of Article on Antenna 1 (AA1) --- p.124 / Chapter 3.3.2.9 --- Number of Article on Antenna 2 (AA2) --- p.127 / Chapter 3.3.2.10 --- Merus Length of Pereopod 7 (MP7) --- p.127 / Chapter 3.3.2.11 --- Summary on Growth Study in Different Salinities --- p.130 / Chapter 3.3.3 --- Morphometric Analysis on Length - Weight Relationship --- p.130 / Chapter 3.4 --- Discussion --- p.134 / Chapter 3.4.1 --- Discontinuous Growth --- p.134 / Chapter 3.4.2 --- Growth Pattern --- p.135 / Chapter 3.4.2.1 --- Molt Cycle - Molt Frequency and Molt Duration --- p.135 / Chapter 3.4.2.2 --- Body Length --- p.136 / Chapter 3.4.2.3 --- Head Length and Merus Length of Pereopod7 --- p.138 / Chapter 3.4.3 --- Morphometric Analysis on Length 一 Weight Relationship --- p.138 / Chapter 3.4.4 --- Sexual Dimorphism --- p.139 / Chapter 3.4.4.1 --- Body Length --- p.140 / Chapter 3.4.4.2 --- Antennae 1 and2 --- p.140 / Chapter 3.4.4.3 --- Gnathopods 1 and2 --- p.141 / Chapter 3.4.5 --- Growth Phase --- p.141 / Chapter 3.4.5.1 --- Merus Length of Pereopod7 --- p.142 / Chapter 3.4.5.2 --- Eye Length --- p.143 / Chapter 3.4.5.3 --- Length of Antennae 1 and2 --- p.143 / Chapter 3.4.5.4 --- Propodus Length of Gnathopods 1 and2 --- p.144 / Chapter 3.4.5.5 --- Summary on Growth Phase --- p.145 / Chapter 3.4.6 --- Optimal Salinity for Growth --- p.145 / Chapter Chapter 4 --- Reproductive Biology of Hyale sp --- p.149 / Chapter 4.1 --- Introduction --- p.149 / Chapter 4.2 --- Materials and Methods --- p.151 / Chapter 4.2.1 --- Fecundity --- p.151 / Chapter 4.2.2 --- Morphometric Relationship between Brood Size and Body Length --- p.152 / Chapter 4.3 --- Results --- p.155 / Chapter 4.3.1 --- Sexual Maturation --- p.155 / Chapter 4.3.2 --- Fecundity --- p.158 / Chapter 4.3.3 --- Duration of Recuperative Period and Incubation Period --- p.161 / Chapter 4.3.4 --- Morphometric Relationship between Brood Size and Body Length --- p.161 / Chapter 4.4 --- Discussion --- p.161 / Chapter Chapter 5 --- Tolerance of Hyale sp. to Temperature and Salinity --- p.170 / Chapter 5.1 --- Introduction --- p.170 / Chapter 5.2 --- Materials and Methods --- p.172 / Chapter 5.2.1 --- Sampling --- p.172 / Chapter 5.2.2 --- Acclimation --- p.172 / Chapter 5.2.3 --- Tolerance Tests --- p.173 / Chapter 5.2.3.1 --- Temperature Tolerance Tests --- p.174 / Chapter 5.2.3.2 --- Salinity Tolerance Tests --- p.175 / Chapter 5.2.4 --- Data Analysis --- p.176 / Chapter 5.3 --- Results --- p.176 / Chapter 5.3.1 --- Temperature Tolerance Tests --- p.176 / Chapter 5.3.2 --- Salinity Tolerance Tests --- p.179 / Chapter 5.4 --- Discussion --- p.183 / Chapter Chapter 6 --- Acute Toxicity of cadmium to Hyale sp --- p.187 / Chapter 6.1 --- Introduction --- p.187 / Chapter 6.2 --- Materials and Methods --- p.188 / Chapter 6.2.1 --- Sampling --- p.188 / Chapter 6.2.2 --- Acclimation --- p.189 / Chapter 6.2.3 --- Cadmium Toxicity Tests --- p.189 / Chapter 6.2.4 --- Data Analysis --- p.190 / Chapter 6.3 --- Results --- p.191 / Chapter 6.4 --- Discussion --- p.200 / Chapter Chapter 7 --- Conclusions --- p.205 / References --- p.208

Thesis (M.S.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 51-55). Also available online.

The intertidal amphipod (Echinogammarus marinus LEACH) exhibits several forms intersexuality and has been considered an ideal model to study reproductive endocrine disruption in Crustacea. This study aimed to investigate both the physiology and transcriptome in intersex E. marinus with the objective of better understanding their reproductive biology and aid the development of biomarkers of de-masculinisation in Crustacea. E. marinus populations from three Scottish (Thurso, Inverkeithing and Loch Fleet) and two English sites (Portsmouth Harbour and Langstone Harbour) were assessed for intersexuality prevalence, sperm counts or microsporidian infection rate. Increased incidence of intersexes and reduced sperm counts were revealed in amphipods from industrial impacted sites. The microsporidian species infecting E. marinus were identified for the first time, and Dictyocoela duebenum and Dictyocoela berillonum were found to be dominant in Inverkeithing and Portsmouth Harbour E. marinus populations, respectively. Microsporidian has been reported as a potential factor inducing intersexes in amphipods. In this study, microsporidian infection was revealed to significantly associate with external intersex males, but not with internal intersex males. A cross-species cDNA microarray was used to characterise the gene expressions of three male phenotypes (normal males, internal and external intersex males), and PCA analysis clearly differentiates the three groups into three separate patches. The de novo transcriptome sequencing was carried out on E. marinus gonadal tissue, by employing Roche 454 pyrosequencing producing one of the largest cDNA libraries for a crustacean species. A total of 12,645 gonadal contigs were assembled from 213,212 sequencing reads, and 1206, 1745 and 782 contigs were found to be male-, female- and intersex-specific genes, respectively. A large number of strongly male and female sex biased gene sequences have been identified and annotated by GO terms which will provide a powerful resource for future studies into the reproductive biology of crustaceans.

Hadal trenches account for the deepest 45% of the ocean (6000 - ~11,000 m). This environment is characterised by perpetual darkness, low temperature and high hydrostatic pressure. Amphipods dominate the scavenging fauna at these depths and are an ideal model organism with which to study this ecosystem. This thesis utilises an unprecedented data set, covering a bathymetric range of over 8000 m and across multiple hadal trench regions. I present both the first attempts at statistically robust ecological analyses of a hadal community and the first extensive examination of the biology and ecology of comparable fauna across multiple trenches. The distinction between “abyssal” and “hadal” communities varies between trenches. I posit that hydrostatic pressure and nutrient flux are primary drivers of community structure. While there is likely a boundary between the abyssal and hadal zones that is fundamentally set by a fauna's physiological limitations, there are also expected to be fauna that are specifically adapted to the environmental conditions (beyond pressure) of trenches. Within the hadal zone, food availability and associated competitive pressures appear to be primary drivers of population structure. Hadal amphipods accumulate extremely large (energy) triacylglycerol lipid reserves. These lipids are highly unsaturated, presumably to maintain metabolic accessibility under the solidifying effects of high hydrostatic pressure and low temperature. Species incorporate high proportions of 18:1(n-9) into their storage lipids, suggesting particular physiological importance. The membrane lipids of two hadal species are highly unsaturated, which I suggest is an adaptive mechanism to mitigate the harmful physiological effects of high hydrostatic pressure and low temperature. I find no evidence of differing physiological tolerance to pressure that would account for the zonation of the species. Rather, each species is understood to be specifically adapted to utilise the varying resources of the upper and lower hadal trench slope respectively.

The role of density of eelgrass shoots in regulating distribution and abundance of gammarid amphipods was investigated. Monthly collections of amphipods were made over a one-year period in a series of treatment plots on Roberts Bank, in southwestern B.C., in which eelgrass (Zostera marina L.) shoots had been thinned to different relative densities. This experiment was originally designed to test the hypothesis that the abundance and diversity of amphipods would be positively related to the density of eelgrass shoots. Due to the rapid recovery of original shoot densities within the plots, however, this hypothesis could not be tested. Consequently, the emphasis of the study was restricted to a consideration of the effect of the disturbance created during removal of shoots on the distribution of amphipods. Collections of amphipods were also made in three areas of different natural densities of Zostera shoots during a three-month period in summer 1984, to assess further the effect of shoot density on the distribution and abundance of amphipods. The role of additional components of habitat heterogeneity, including drift algae and a second species of seagrass, Zostera japonica, in modifying the community dynamics of the amphipods was also studied. No relationship between the density of Zostera shoots and the abundance and diversity of amphipods was found. The amphipod community was dominated by Corophium acherusicum and the distribution of this species, as well as that of the other most frequently collected species, appeared to be regulated by the seasonality of macrophyte biomass. Peak abundances of amphipods occurred in the late summer and autumn when large amounts of drift algae and eelgrass detritus were present at the sediment surface. This decaying plant material is an important source of food for detritivores such as gammarids and its seasonal abundance was reflected in the rapid growth of populations of amphipods. The floating mats of drift algae, such as Ulva sp., also contributed significantly to the carrying capacity of the eelgrass meadow by providing spatial refuges to amphipods which are targets of fish and bird predation. The role of habitat heteogeneity in determining the distribution of the dominant species of amphipods, with reference to competition and predation, was discussed. / Science, Faculty of / Zoology, Department of / Graduate

The "equilibrium partitioning theory" is one of the most widely used models to evaluate the bioavailability of sediment-associated, nonpolar, organic contaminants and it makes specific assumptions regarding the factors that influence this bioavailability. The objective of this research was to test two assumptions of this theory: (1) that benthic organisms are exposed to a constant, equilibrium-predicted concentration of a contaminant in interstitial water, regardless of the behavior of the organism; and (2) that exposure to interstitial water in a sediment exposure system is equivalent to the exposure in a water-only exposure system. The effect of behavior on the exposure to sediment-associated phenanthrene was tested by exposing three marine amphipod species (with different burrowing behaviors) to the polycyclic aromatic hydrocarbon (PAH) phenanthrene under two exposure conditions, one with spiked sediment and clean overlying water and the other with spiked sediment and contaminated overlying water. This was done to evaluate the extent to which the burrow irrigating behavior and the different tube or burrow building behavior exhibited by the amphipod species could effect the accumulation of sediment-associated phenanthrene. The assumption of equivalent exposure between sediment and water systems was tested by exposing the amphipods to the same concentration of phenanthrene in a water-only versus sediment exposure system. In both series of experiments, the bioaccumulation of phenanthrene by the amphipods was followed over 72 hours and bioaccumulation kinetics calculated for each species and exposure treatment. The results indicated that the burrow irrigating behavior of benthic marine amphipods can significantly affect the exposure of these amphipods to sediment-associated contaminants by diluting the concentration of contaminant in the interstitial water surrounding the organisms with overlying water. Additionally, there was a species dependent decrease in exposure based upon the tube or burrow building strategy used by the amphipod species. The results also indicated that exposure in a sediment system was not equivalent to exposure in a water-only system. The bioaccumulation of phenanthrene was significantly higher for all three species in water versus sediment. However, the interpretation of the results from this second series of experiments was complicated by the degradation of phenanthrene in the sediment-only exposure. / Graduation date: 1998

Two zoologists with considerable experience in the Canadian Arctic suggested to the writer that the “Gammarus Problem” would be an extremely interesting subject for investigation, and one which has several advantages, for material is relatively easy to obtain, and there are a number of species available. The precise studies on the species and sub-species of this amphipod genus in British estuaries are well known, and have been cited as examples in discussions on speciation and “new systematics”. In North America such studies are lacking and the time seemed opportune to try to elucidate the relationships between some of the forms living on these shores. In particular the species from northern waters were of interest. Dr. E.L. Bousfield (1958) has described the fresh-water amphipods of North America, and is currently preparing an account of the systematics of coastal species. This account provided material for the present discussion on the general relationships of North American species, but as it has not yet been published the reference “personal communication” or “pers. comm.” is used throughout the discussion. [...]