Assessment of the phototoxicity of weathered Alaska North Slope crude oil to juvenile pink salmon

Petroleum products are known to have greater toxicity to the translucent embryos and larvae of aquatic organisms in the presence of ultraviolet radiation (UV) compared to toxicity determined in tests performed under standard laboratory lighting with minimal UV. This study assessed the acute phototoxicity of the water accommodated fractions of weathered Alaska North Slope crude oil (ANS) to juvenile pink salmon, which are a heavily pigmented life stage. Fish in the highest ANS treatments exhibited melanosis, less mobility, reduced startle response, erratic swimming, and loss of equilibrium. Gills from fish exposed to ANS had elevated levels of hydroperoxides in oil-only, UV-only, and oil+UV treatments compared to control fish, which was indicative of increased lipid peroxidation in gill tissue. Under the test conditions of moderate salinity, low UV and high short-term oil exposure there were no indications of photoenhanced toxicity as assessed by elevation of mortality, behavioral impairment, or gill lipid peroxidation in oil+UV treatments. The results of this study suggest that pink salmon may be at less risk from photoenhanced toxicity compared to the translucent early-life stages of several other Alaska species.     

Validation of otolith-increment age estimates for a deepwater fish species,the warty oreo Allocyttus verrucosus,by radiometric analysis

Otolith increment age estimates for a deepwater species, Allocyttus verrucosus, were validated by comparison with the results from ²¹⁰Pb:²²⁶Ra radiometric analysis. Transverse sectioning and subsequent grinding of otoliths to a thickness of 0.2 mm revealed increments which provided age estimates for a range of fish sizes. Age estimates ranged from 7 yr for an immature fish of 15.2 cm total length (TL) to 130 yr for a female fish of 36.5 cm TL. Age at maturity was estimated as 28 yr for females and 24 yr for males. In comparison, radiometric analysis of whole otoliths, using a single linear otolith-mass growth-rate model suggested maximum ages of 130 to 170 yr for fish of 34 to 35 cm TL. Radiometric ages were also recalculated using a two-phase otolith-mass growth-rate model in which the growth rate was assumed to slow after maturity to 90% of the pre-maturity rate. This reduced the maximum age to 132±15 yr for a mean fish length of 34.5 cm. Age at maturity for females was estimated at 34 yr. The similarity between age estimates from otolith-increment counts and radiometric analysis strongly supports the accuracy of results from both methods, and encourages further use of such comparisons as an alternative to traditional validation techniques.     

Labyrinthula sp., a marine slime mold producing the symptoms of wasting disease in eelgrass,Zostera marina

Coastal ecosystems along the eastern United States are presently threatened by a recurrence of the wasting disease of eelgrass, Zostera marina L. Using Koch's postulates, a species of the marine slime mold, Labyrinthula, is identified as the causal microorganism of this disease. Our disease tests for pathogenicity performed on eelgrass, using four Labyrinthula spp., indicate only one species produces the disease symptoms identical to those found associated with the wasting disease. The pathogenic Labyrinthula sp. has morphological characteristics that distinguish it from the other three species. Identification of Labyrinthula spp. is difficult because species described in the literature are not clearly characterized or identifiable. Tests at various salinities demonstrate that disease symptoms appear infrequently at salinities of 10%. or less.     

A Test of the Vegetation Mosaic Hypothesis: A Hypothesis to Explain the Decline and Extinction of Australian Mammals

The vegetation mosaic hypothesis suggests that medium-sized mammals occupying arid and semi-arid areas of Australia require a habitat that is a fine-grained mosaic of different vegetation types or seral stages. This mosaic is believed to have been created in the spinifex deserts of central Australia by Aboriginal burning practices. Its loss in the period 1940–1960 is postulated to be a primary reason for both major reductions in range and mainland extinctions of many species of medium-sized mammals at this time. This study measured the responses of three species of medium-sized mammals to vegetation patterns within spinifex grasslands that ranged from comparatively uniform to highly diverse. The abundance, condition, and reproductive status of golden bandicoots (Isoodon auratus) , northern brush-tailed possums (Trichosurus vulpecula arnhemensis) , and burrowing bettongs (Bettongia lesueur) were assessed within vegetation mosaics of various scales on Barrow Island, off the northwest coast of Australia. Scale of mosaic proved to have no significant effect on the numbers, condition, or reproductive status of any of the three species. Similarly, the creation of fine-grained mosaics of early seral-stage vegetation mixed within climax vegetation by extensive oil-field operations over nearly half the island had no significant effect on the number or condition of animals. Hence, scale of mosaic seems unlikely to be related to the mainland decline or extinction of these species. The pattern of decline and extinction on the mainland but continued survival on offshore islands is more consistent with the presence (mainland) or absence (islands) of introduced predators (foxes and cats) and herbivores (rabbits and stock).     

Safe alternative cancer therapy using electromagnetic fields

This article highlights recent research on the beneficial use of selected low frequency electromagnetic fields (EMF) as a safe alternative therapy for treatment of cancer and other health problems. It is shown that EMF therapy provides a safe alternative and adjunct modality for the treatment of cancer and other health problems, and therefore, research in this field deserves more support. The paper also discusses some reports and hypothesis of potential risk of human exposure to low frequency EMF, mainly to the power line frequency of 60 Hz.     

Microsporidia infections in the amphipod, <Emphasis Type="Italic">Echinogammarus marinus</Emphasis> (Leach): suggestions of varying causal mechanisms to intersexuality

A notable body of research has established a clear link between intersexuality and the feminising influence of microsporidia infection in amphipods. In this study, we investigated the relationship between microsporidia infection and intersexuality in the amphipod Echinogammarus marinus (Leach) from Portsmouth, southern England. The analysis revealed a male-biased population (~2:1) harbouring both Dictyocoela berillonum and Dictyocoela duebenum microsporidia, with ~38 and 6% of animals displaying ‘high’ levels of infection, respectively. We also reveal the presence of several intersex phenotypes: intersex females (1%) that possess genital papillae. Two male intersex phenotypes—internal intersex (8.2%), possessing an oviduct structure on their testes, and external intersex males (4.4%), which possess external brood plates. We found a statistically significant relationship between D. berillonum infection and the external intersex male phenotype; however, the male-biased population and low levels of female infection suggest that the correlation may not be the result of incomplete feminisation. In addition, we found that the internal and external intersex characteristics are rarely seen on the same specimen, suggesting that the male intersex phenotypes are caused by distinct mechanisms. In combination, these findings are suggestive of a more complex relationship between amphipod intersexuality and their microsporidia than had previously been recognised.     

Governing Change: Land-Use Change and the Prevention of Nonpoint Source Pollution in the North Coastal Basin of California

Many rural areas in the United States and throughout much of the postindustrial world are undergoing significant ecological, socioeconomic, and political transformations. The migration of urban and suburban dwellers into rural areas has led to the subdivision of large tracts of land into smaller parcels, which can complicate efforts to govern human–environmental problems. Non-point source (NPS) pollution from private rural lands is a particularly pressing human–environmental challenge that may be aggravated by changing land tenure. In this article, I report on a study of the governance and management of sediment (a common NPS pollutant) in the North Coastal basin of California, a region undergoing a transition from traditional extractive and agricultural land uses to rural residential and other alternative land uses. I focus on the differences in the governance and management across private timber, ranch, residential, vacation, and other lands in the region. I find that (1) the stringency and strength of sediment regulations differ by land use, (2) nonregulatory programs tend to target working landscapes, and (3) rural residential landowners have less knowledge of sediment control and report using fewer sediment-control techniques than landowners using their land for timber production or ranching. I conclude with an exploration of the consequences of these differences on an evolving rural landscape.