Three criteria, development, flight, and oviposition, were used to compare a laboratory-adapted and wild-type colony of Trichoolusia ni. The laboratory-adapted colony was further examined to determine the effect of larval crowding and starvation on the above criteria. The laboratory-adapted colony displayed a shorter development time and higher immature mortality than the wild-type colony. Differences in flight activity between and within the colonies were observed. Wild-type mated females were the most active group of tested moths. The oviposition rate of the laboratory-adapted colony was higher than the wild-type colony. Innate differences in parent populations and selective pressures during the rearing of the laboratory-adapted colony may explain differences between the colonies. Larval crowding resulted in prolonged development time, lower pupal weight, increased larval mortality, and increased adult longevity. Starvation during the larval stage produced similar changes. Flight activity declined with the degree of larval crowding and starvation. Larval crowding and starvation also resulted in a decline in adult fecundity and mating frequency. It is postulated that stress to the larvae resulted in a decline in energy sources to be used in the adult stage, producing docile adults. / M.S.

This field study investigated the short-term effects of riparian defoliation by gypsy moth larvae on three aspects of headwater stream ecology, water quality, benthic macroinvertebrate community structure, and benthic macroinvertebrate function (expressed as secondary production). The experimental design was to compare measurements in three streams that were extensively defoliated by gypsy moth larvae (defoliated treatment), with three streams that were not affected by gypsy moth larvae (reference treatment). Although the riparian canopy became much more open after defoliation, I observed no significant differences in any water quality parameters except temperature, which was slightly elevated for a brief period after defoliation. There was a significant increase in the amount of detritus (frass and orts) falling into defoliated streams in the spring, which was followed by a significant decrease in the of amount detritus falling into defoliated streams in autumn. Many measures of community structure were analyzed, but only the Index of Biotic Similarity demonstrated a significant difference, indicating that, at most, only slight changes in community structure occurred. Secondary production of two representative aquatic insects, Peltoperlidae (shredder) and Diplectrona modesta (collectorfilterer), was not affected by defoliation. Glossosoma nigrior (scraper) achieved higher production because of a second-generation being induced by elevated temperature. I conclude that the short-term effects of riparian defoliation by gypsy moth larvae were minor. / Master of Science

A little-known approach to toxicity testing--based on negative phototaxis of larval <u>Aedes aegypti</u>--was investigated as a contribution to the search for rapid methods applicable to the field of water pollution control. Zinc and copper were the toxicants tested. All tests were conducted with a standard "synthetic" dilution water. A mosquito colony was established to provide a uniform supply of test larvae. Preliminary tests were performed on the acute toxicity of zinc and copper against <u>A. aegypti</u> larvae, as well as tests on larval growth and development at various concentrations of the metals. For the photomigration toxicity tests, two juxtaposed troughs were used, one containing the test solution, the other a control. Third instar larvae migrated away from a six-watt fluorescent light for two minutes per run. This was repeated at intervals until 50% were unable to migrate 50 cm in 120 sec. Photographs were taken of the larval migrations. From the pictures an empirical criterion was derived (the 40-cm, 60-sec ET₅₀) through a series of graphical interpolations. All inactivation analyses were based on this criterion. From time-inactivation regression lines, exponential toxicity curves were obtained by interpolation. The curves were of an unusual shape, depicting the characteristic nature of the dosage-response. The sensitivity of the inactivation technique was comparable to that of the acute toxicity tests. However, inactivation was far quicker; depending on concentration, it occurred within one to five hours. By all methods used in this study, zinc and copper were judged to be slow-acting and of low overall toxicity. Copper was, however, consistently more toxic than zinc by at least one order of magnitude. The ET₅₀ in 10 ppm Cu⁺⁺ was 147 min.; in 10 ppm Zn⁺⁺, it was 209 min. Some possible improvements in technique were discussed. It was suggested that the photornigration approach to toxicity testing can be of definite practical use to biologists in water pollution control. / Master of Science

Use of a magnetic compass has been demonstrated in all major classes of vertebrates as well as several classes of invertebrates, and is proposed to involve a photo-induced radical pair mechanism (RPM). My dissertation research consisted of characterizing a magnetic compass in a model species, Drosophila melanogaster. Preliminary experiments were carried out with adult flies, however, due to the behavioral complexity of adult responses a new behavioral assay of magnetic compass orientation was developed using larval Drosophila that elicits a robust magnetic compass response in a trained magnetic direction. This manuscript describes experiments that were conducted showing that larval magnetic compass orientation: 1) demonstrates a complex 3-dimensional pattern of response consistent with a RPM; 2) is consistent with a receptor mechanism that utilizes short- and long-wavelength antagonistic photopigments, proposed to explain wavelength dependent effects in vertebrates (e.g. amphibians and birds); and 3) produces axially symmetrical patterns of response with respect to the geomagnetic field. Additionally, tests of adult Drosophila under low and high intensities of monochromatic long wavelength light revealed a similar behavioral response to varying intensities of monochromatic light as previously reported in migratory birds (E. rubecula). These findings indicate that the magnetic compass of larval Drosophila shares a common functional architecture and similar biophysical mechanism with that of at least some vertebrates (e.g. amphibians and possibly birds), suggesting that the magnetic compass of modern vertebrates may have evolved once in a common ancestor of these three lineages over 450 million years ago. Furthermore, findings indicating a spontaneous preference for magnetic directions in D. melanogaster larvae suggest that a light-dependent magnetoreception mechanism is more widespread in insects than was previously suspected. The development of a behavioral assay to study the light-dependent magnetic compass in an organism with a simple nervous system, a limited behavioral repertoire, and with the possibility of using the full power of modern molecular and genetic techniques holds considerable promise to increase our understanding of the biophysical mechanism(s) and neurophysiological structures underlying magnetic orientation in terrestrial animals. / Ph. D.

Larval fish distributions were determined in the lower Winfield Pool, Kanawha River, West 85, Virginia, using a 0.5-m plankton net and a 1-m² dropbox. Five habitats were sampled with the plankton net, 3 habitats with the dropbox. The 5 deep water water habitats, greater than 1.5-m in depth, sampled by the plankton net included surface tows in Bill's Creek backwater, main channel border upstream and downstream of Little Guano backwater, and Little Guano Creek backwater, where deep tows (1.5 m deep) were also taken. The 3 shallow water habitats, less than 1 m in depth, sampled by the dropbox included open water over silt substrate, open water over a sand substrate, and emergent vegetation. <i>Lepomis</i> species, emerald shiners (<i>Notropis atherinoides</i>), and gizzard shad (<i>Dorosoma cepedianum</i>) were the dominant taxa. The emerald shiner taxa could also have included some larvae of <i>Notropis</i> species which are also present in the Kanawha River but whose larvae have not been described. Overall, the mean total larval density did not differ between the backwater or the main channel borders but the species associated with each habitat differed greatly. The <i>Lepomis</i> larvae were found predominantly in backwater areas. These areas provide suitable spawning sites for many centrarchids of this river. Upon leaving the nest, the <i>Lepomis</i> larvae moved into the deeper open water areas within the backwater. After reaching the juvenile stage, these same larvae returned to the shallow water habitats where they inhabited vegetated areas. Emerald shiner larvae, while present in both backwater and main channel habitats, were most abundant in the main channel borders. This is probably a result of their parent's pelagic spawning strategy. In all habitats, emerald shiner larvae predominated in the upper 1 m of water. Upon becoming larger, the emerald shiner larvae appeared in the backwaters. This increase in numbers could be due to movement, differential mortality, or higher growth rates. Other cyprinids (excluding emerald shiners and carp) were equally abundant in both backwater and main channel areas. These other cyprinid larvae were also distributed equally, Gizzard shad larvae were found predominantly in the main channel borders. Presumably, these higher densities were the result of main channel spawning. The gizzard shad larvae present in the backwater areas were distributed evenly throughout the water column. Overall, the backwaters were important for the nest-building species found in the river and also for the larger larvae of the pelagic species, and thus acts as a nursery area for these species. Therefore, the backwaters do seem to be important for the fishery of the Kanawha River. / Master of Science

Scheltema (1971, 1978) and others have proposed that extensive larval dispersal allows marine invertebrate species to establish great geographic ranges; several studies along a single margin of an ocean basin have supported this proposal (Shuto, 1975; Hansen, 1978). This study makes use of the fossil record to examine larval dispersal patterns on a larger geographic scale: across an entire ocean basin. Sixteen genera/subgenera of marine prosobranch gastropods were selected as the data base for the study. Eight of the genera were widely distributed (have fossil representatives on both the eastern and western margins of the North Atlantic Ocean) during the Neogene, and eight genera were narrowly distributed (fossil representatives were restricted to either the eastern or the western margin of the North Atlantic) during the Neogene. The larval forms of fossil species within each genus were inferred by examination of protoconch morphologies, according to guidelines established by modern biologists (Robertson, 1974; Shuto, 1975). The two groups were compared using statistical methods to test a null hypothesis of no relationship between geographic distribution and larval form. The results of the study reject the null hypothesis, and support the conclusion that Neogene marine prosobranch genera that are widely distributed across the North Atlantic Ocean basin are much more likely to exhibit planktotrophic larval development than are prosobranch genera that are geographically limited to a single margin of the ocean basin. / Master of Science

Toxicity of copper to larval <I>Mercenaria mercenaria</I> was evaluated with static non-renewal and continuous renewal methods that permitted daily observation of mortality, activity, development, and metamorphosis without subsampling. Clam larvae, 100 - 150 microns, were held for up to two weeks in small, 30 mm, sealed petri plates during static assays with excellent survival of control organisms, low evaporative losses, and relatively low between replicate variability. An eight day LC50 of 12 micrograms / liter for six day old organisms was determined as well as EC50s (active swimming). EC50s at 24 hours were as much as much as seven times lower than LC50s after 24 hours of exposure. Flow - through assays were conducted with a modified petri dish design. Two sections from opposing sides of a 30 mm petri dish were removed and covered with 35 micron polyester screening. This dish (organism dish) was placed in an outer catch dish that captured the effluent toxin as it passed through the screening and routed it to a catch bottle for water quality analysis. The toxicant feed line entered through the catch dish cover and slowly dripped toxin into the organism dish. Water quality in the flow - through assay remained excellent. Survival of control organisms in the flow - through assay was lower than in static assays, but metamorphosis was not delayed as had been observed in static assays. Data variability was low enough that statistical distinctions were made between the effects of copper on metamorphosis. A non-standard "M" shaped survival response was observed in all assays. The responses generating the "M" shaped response in the static petri assay were statistically different from each other. Activity, as judged by swimming, in organisms was not observed to follow the "M" shaped pattern. Instead, it decreased exponentially with increasing copper concentrations. Static experiments with unfed clams, observations of activity, and data from experiments in copper accumulation by algae led to a theory relating the unusual dose response to food consumption and its relationship to the effective dose of copper to which the larval clams were exposed. / Master of Science

published_or_final_version / abstract / Biological Sciences / Master / Master of Philosophy

Triclosan and triclocarban are antimicrobials found in numerous consumer products, while caffeine is the most commonly consumed stimulant by humans. This study was undertaken to determine the effects of triclosan, triclocarban, and caffeine on the development and physiology of amphibian larvae. LC50 values of triclosan and triclocarban were determined after 96 hours for three North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a common amphibian developmental model: Xenopus laevis. Amphibian larvae were most sensitive to triclosan and triclocarban exposure during early development based upon 96-hour LC50 values. Heart rates for X. laevis and North American larvae exposed to triclosan were variable throughout development. However, significantly lower heart rates were observed in all larvae exposed to triclocarban. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to triclosan were significantly affected in larvae exposed to ½ LC50 and the LC50 concentration. Metabolic rates of X. laevis larvae exposed to triclocarban were significantly affected by exposure to ½ LC50 concentrations in three of four stages investigated. No significant differences were observed in North American larvae exposed to triclocarban. Tissue uptake, lipid uptake, tissue bioconcentration factor (BCF) and lipid BCF of triclosan and triclocarban were investigated in three developmental stages of X. laevis, and in one developmental stage of B. woodhousii woodhousii, and R. sphenocephala. For most tissue and lipid uptake values, a significant increase was observed as exposure concentration increased. Tissue and lipid BCF values were dependent upon both stage and species. Chronic and acute effects of caffeine were determined in X. laevis larvae. Acute 96-hour LC50 values in four developmental stages were > 75,000 ug L-1 caffeine and heart rates were significantly different at the two earliest developmental stages. Larvae chronically exposed to caffeine reached metamorphosis at the same time as controls. Changes in chronic heart rate were dependent upon stage of development and exposure concentration. This research indicates that the toxicity of amphibian larvae exposed to triclosan, triclocarban, and caffeine appears to be dependent upon species and developmental stage, with early developmental stages being most sensitive to contaminant exposure.

Nearshore hypoxia within the Northern California Current (NCC) system is a seasonal phenomenon caused by coastal upwelling and occurs mainly during late-summer and early fall. The effects of low oxygen levels on fish and invertebrate communities, particularly during early-life history stages, however, are poorly known for this area. I investigated the effects of hypoxia on the density, community structure, vertical and horizontal distribution of fish larvae and juveniles, as well as body condition of juveniles, along the central Oregon and Washington coasts during the summers of 2008 - 2011. During this sampling period, bottom dissolved oxygen (DO) values ranged from 0.49 to 9.85 ml l�����, and the number of hypoxic (e.g., < 1.4 ml l�����) stations sampled was low compared to 2002 and 2006 (only 54 sampling stations for the ichthyoplankton study out of 493, and only 12 stations out of 90 for the benthic juvenile study). From the ichthyoplankton study, I found that the overall density of fish larvae increased as bottom-DO values increased; however, the effect on individual species density was limited. Between 44.65 ��N and 46.00 ��N (~Florence, OR ��� Astoria, OR), fish larvae altered their vertical distribution when bottom-DO was low by rising in shallower water layers. From the benthic juvenile study, I found that English sole (Parophrys vetulus), butter sole (Isopsetta isolepis), speckled sanddab (Citharichthys stigmaeus) and Pacific sanddab (Citharichthys sordidus) dominated the catch with annual variation in abundances. Species composition, abundance and length had strong relationships with depth. Species abundance for English sole (< 75 mm), speckled sanddab (<100 mm) and Pacific sanddab also increased with increased bottom-DO. However, the body condition of butter sole (< 75 mm) and of large speckled sanddab (���100 mm) increased with decreased bottom-DO. Overall my research elucidates important patterns of larval and juvenile fish distribution within the NCC during summer. In both studies I have found a limited effect of DO on abundance, distribution and community assemblages. Variables other than DO, such as depth, season and location, dominated the explained variance of the intervening multivariate and univariate analysis. However, due to the paucity of samples during hypoxic events, continued monitoring of nearshore larval and juvenile species over varying hypoxic conditions is necessary for understanding the impact of hypoxia on these communities and subsequent adult populations. / Graduation date: 2013