The paradox of pelagic food webs on the Bering-Chukchi continental shelf

Thesis (Ph.D.) University of Alaska Fairbanks, 1987Prolific primary production and spectacular populations of marine birds and mammals in the northern Bering Sea were for many years considered to be a paradox of an environment that should have had low production, as is typical of shallow continental shelves elsewhere. However, a "river" of oceanic water, Anadyr Water, originating along the continental slope of the Bering Sea carries a perpetual supply of nutrients and biota onto this northern shelf that transforms part of the region into one that is extremely productive at all trophic levels. Diatoms grow profusely throughout the ice-free season and, together with oceanic zooplankton advected in the Anadyr stream, provide the energy base for rich pelagic and benthic food webs. Contrasting with the highly productive pelagic regime is one associated with Bering Shelf Water and Alaskan Coastal Water. Both of these water masses originate over the shallow shelf of the northern and eastern Bering Sea, and are typically nutrient-poor following the spring phytoplankton bloom. Terriginous nutrients introduced by the Yukon and other rivers are not sufficient to elevate primary production above a low level typical of inner shelf regions. The oceanic zooplankton are excluded from this environment, and populations at higher trophic levels are small. The consequence of these contrasting physical regimes is that discrete oceanic and inner shelf food webs coexist in a small geographic region where only a coastal ecosystem is expected

Electroconvulsive shock- or puromycin-induced retention deficits in goldfish given two active-avoidance sessions

In a factorial design, goldfish received 15 active-avoidance training trials on Days 1, 7, and 13 followed by electroconvulsive shock (ECS) or no treatment after the training session on Days 1 and 7. The final retention deficits observed when ECS was given after the first session only or after the second session only were similar. Fish given ECS after both sessions showed a cumulative deficit that approximated the sum of the two effects. Similar results were obtained with puromycin. These data support the hypothesis that ECS and puromycin impair only recent learning. Retrograde amnesia gradients confirmed that the efficacy of these amnestic agents was not altered by a second administration.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21642/1/0000026.pd

Direct ipsilateral retinal projections in goldfish (Carassius auratus)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22948/1/0000515.pd

Puromycin-induced retention deficit in goldfish as a function of attained training performance level

Goldfish received either 20 or 50 active avoidance training trials followed by puromycin (or no-treatment) and 10 retraining trials either 1 or 7 days following training. While 50 trials resulted in significantly more training avoidances than 20 trials, the groups which received puromycin showed equivalent retention deficits on Day 7. A within-group comparison of fish whose training performance was high or low further revealed that the degree of the retention deficit was independent of achieved training performance level. These data support the hypothesis that puromycin interferes with a memory fixation process that is initiated only upon completion of the training session.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21711/1/0000103.pd

An Independent Review of USGS Circular 1370: An Evaluation of the Science Needs to Inform Decisions on Outer Continental Shelf Energy Development in the Chukchi and Beaufort Seas, Alaska

Reviews the U.S. Geological Survey's findings and recommendations on Alaska's Arctic Ocean, including geology, ecology and subsistence, effect of climate change on, and impact of oil spills. Makes recommendations for data management and other issues

Supporting strong families and capable communities through cross-national research

Background Mental and behavioral ill-health are growing global problems and while there are promising evidence-based approaches aimed at reducing their impact, availability of services varies greatly, not only across nations, but also between urban, regional, and remote locations. Rural areas face accessibility and acceptability challenges related to mental health services that are similar to barriers experienced in developing countries. Initiatives to address mental health challenges in under-served rural areas can inform global mental health strategies. Methods Using a public health approach, we illustrate how innovations in rural communities build community capacity and capability in areas that are currently, and are likely to remain, under-served by specialist mental health services. We provide examples of initiatives and key principles of action from three locations in Nebraska, United States of American and New South Wales, Australia to highlight similarities of context and practice. Results While each of the initiatives was developed independently, there are striking similarities across them. Similarities in initiatives include: a) recognition that solutions developed in urban settings are not necessarily the most effective in under- served rural areas, b) engagement of community members is needed to ensure acceptance of initiatives in target communities, c) each initiative involved community members acting on their own behalf with an emphasis on prevention and early intervention, and d) research is a key aspect that informs practice and has local relevance. Commonalities of contexts and environments may have played an important role in the similarities. Conclusions Linking initiatives within and between countries can expand local, national, and global reach and impacts. If we are to meet lofty global goals related to health and wellbeing, cross-national collaborations are needed to share resources, expand expertise, and stimulate ideas necessary to develop and enhance local and global initiatives. High-income country partnerships addressing mental health in under-served areas, such as rural communities, can play a vital role in contributing to global mental health solutions

Does Atrazine Influence Larval Development and Sexual Differentiation in Xenopus laevis?

Debate and controversy exists concerning the potential for the herbicide atrazine to cause gonadal malformations in developing Xenopus laevis. Following review of the existing literature the U.S. Environmental Protection Agency required a rigorous investigation conducted under standardized procedures. X. laevis tadpoles were exposed to atrazine at concentrations of 0.01, 0.1, 1, 25, or 100 μg/l from day 8 postfertilization (dpf) until completion of metamorphosis or dpf 83, whichever came first. Nearly identical experiments were performed in two independent laboratories: experiment 1 at Wildlife International, Ltd. and experiment 2 at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB). Both experiments employed optimized animal husbandry procedures and environmental conditions in validated flow-through exposure systems. The two experiments demonstrated consistent survival, growth, and development of X. laevis tadpoles, and all measured parameters were within the expected ranges and were comparable in negative control and atrazine-treated groups. Atrazine, at concentrations up to 100 μg/l, had no effect in either experiment on the percentage of males or the incidence of mixed sex as determined by histological evaluation. In contrast, exposure of larval X. laevis to 0.2 μg 17β-estradiol/l as the positive control resulted in gonadal feminization. Instead of an even distribution of male and female phenotypes, percentages of males:females:mixed sex were 19:75:6 and 22:60:18 in experiments 1 and 2, respectively. These studies demonstrate that long-term exposure of larval X. laevis to atrazine at concentrations ranging from 0.01 to 100 μg/l does not affect growth, larval development, or sexual differentiation

The effect of memory blocking antibiotics and their analogs on acetylcholinesterase

The ability of antibiotics to inhibit acetylcholinesterase was measured in homogenates of goldfish brain. Puromycin aminonucleoside was the most potent inhibitor followed by puromycin, cycloheximide and acetoxycycloheximide. Puromycin effectively impaired retention of active-avoidance learning in goldfish when injected either immediately before or after training, while puromycin aminonucleoside did not regardless of injection time. These results suggest that the known amnestic effects of puromycin, cycloheximide and acetoxycycloheximide are not a consequence of interference with acetylcholinesterase.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21729/1/0000121.pd