Directional selection by fisheries and the timing of sockeye salmon (Oncorhynchus nerka) migrations.

The timing of migration from feeding to breeding areas is a critical link between the growth and survival of adult animals, their reproduction, and the fitness of their progeny. Commercial fisheries often catch a large fraction of the migrants (e.g., salmon), and exploitation rates can vary systematically over the fishing season. We examined daily records of sockeye salmon (Oncorhynchus nerka) in the Egegik and Ugashik management districts in Bristol Bay, Alaska (USA), for evidence of such temporally selective fishing. In recent years, the early migrants have experienced lower fishing rates than later migrants, especially in the Egegik district, and the median migration date of the fish escaping the fisheries has been getting progressively earlier in both districts. Moreover, the overall runs (catch and escapement) in the Egegik district and, to a lesser extent the Ugashik district, have been getting earlier, as predicted in response to the selection on timing. The trends in timing were not correlated with sea surface temperature in the region of the North Pacific Ocean where the salmon tend to concentrate, but the trends in the two districts were correlated with each other, indicating that there may be some common environmental influence in addition to the effect of selection. Despite the selection, both groups of salmon have remained productive. We hypothesize that this resilience may result from representation of all component populations among the early and late migrants, so that the fisheries have not eliminated entire populations, and from density-dependent processes that may have helped maintain the productivity of these salmon populations.     

A Value-Informed Framework for Interdisciplinary Analysis: Application to Recovery Planning for Snake River Salmon

Economic and social variables, in addition to biological variables, are often critical forces in directing recovery planning for threatened and endangered populations. Although including these variables in scientific analyses for recovery planning may be important, there is little agreement on how to integrate the relevant disciplines. The dilemma associated with interdisciplinary collaboration is that, while a diversity of values and perspectives is unavoidable, this diversity stands as a barrier to agreement on an integrative research approach. We describe a general framework for interdisciplinary analysis designed to support recovery planning that does not rely on choosing a single interdisciplinary approach. Rather, it uses value conflicts potentially arising in an interdisciplinary setting to select a diverse set of scientific approaches relevant to a particular conservation effort. We apply this framework to recovery planning for threatened Snake River chinook salmon ( Oncorhynchus tshawytscha ) and examine the implications of conflicts over the acceptability of institutional change, technological solutions, and transferability of recovery effort across groups responsible for the current status of the species.     

Sex ratio,monogamy and breeding success in the Midas cichlid (Cichlasoma citrinellum)

Summary The Midas cichlid (Cichlasoma citrinellum) is a large, aggressive monogamous fish from the Great Lakes of Nicaragua. It lives in an ecosystem where breeding sites are at a premium and where breeding success can be low. I tested the strength of the pair bond by manipulating the sex ratios in captive groups, using ratios of 1:1, 2:1, 4:1, 1:2 and 1:4 (:). No polygamy was seen at any of the ratios. Departure from a ratio of 1:1 decreased breeding success for those pairs that formed. Both sexes appeared to enforce the pair bond but did so in different ways: females attacked males and females equally but males attacked other males significantly more than they did females. These results, coupled with field observations, indicate the Midas cichlid is obligated to monogamy by the demands of competition for breeding sites, the need for two parents to protect the fry and by energetic constraints.     

Spatial variability and temporal stability of throughfall deposition under beech (Fagus sylvatica L.) in relationship to canopy structure

Although the spatial variability of throughfall (TF) in forest ecosystems can have important ecological implications, little is known about the driving factors of within-stand TF variability, particularly in deciduous forests. While the spatial variability of TF water amount and H+ deposition under a dominant beech (Fagus sylvatica L.) tree was significantly higher in the leafed period than in the leafless period, the spatial TF deposition patterns of most major ions were similar in both periods. The semiannual TF depositions of all ions other than H+ were significantly positively correlated (r=0.68-0.90, p<0.05) with canopy structure above sample locations throughout the entire year. The amounts of TF water and H+ deposition during the leafed period were negatively correlated with branch cover. We conclude that the spatial heterogeneity of ion deposition under beech was significantly affected by leaves in the growing period and by branches in non-foliated conditions.     

A novel cell division factor from tobacco 2B-13 cells that induced cell division in auxin-starved tobacco BY-2 cells

Effects of auxin as plant hormones are widespread; in fact in almost all aspects of plant growth and development auxin plays a pivotal role. Although auxin is required for propagating cell division in plant cells, its effect upon cell division is least understood. If auxin is depleted from the culture medium, cultured cells cease to divide. It has been demonstrated in this context that the addition of auxin to auxin-starved nondividing tobacco BY-2 cells induced semisynchronous cell division. On the other hand, there are some cell lines, named habituated cells, that can grow without auxin. The cause and reason for the habituated cells have not been clarified. A habituated cell line named 2B-13 is derived from the tobacco BY-2 cell line, which has been most intensively studied among plant cell lines. When we tried to find the difference between two cell lines of BY-2 and 2B-13 cells, we found that the addition of culture filtrated from the auxin-habituated 2B-13 cells induced semisynchronous cell division in auxin-starved BY-2 cells. The cell division factor (CDF) that is responsible for inducing cell division in auxin-starved BY-2 cells was purified to near-homogeneity by sequential passage through a hydroxyapatite column, a ConA Sepharose column and a Sephadex gel filtration column. The resulting purified fraction appeared as a single band of high molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels by silver staining and was able to induce cell division in auxin-starved BY-2 cells. Identification of the protein by MALD-TOF-MS/MS revealed that it is structurally related to P-glycoprotein from Gossypioides kirkii, which belongs to ATP-binding cassette (ABC)-transporters. The significance of CDF as a possible ABC-transporter is discussed in relationship to auxin–autotrophic growth and auxin-signaling pathway.     

Improving environmental risk management through historical impact assessments

A historical contaminant impact assessment was conducted at 48 heavy manufacturing facilities located in 20 different states for a U.S.-based company. The facilities evaluated were industrial manufacturing sites that operated for as long as 100 yr and used several types of hazardous substances, including solvents and degreasers, oils and other petroleum products, paints and pigments, and heavy metals. The purpose of conducting the impact assessment was to provide direction and guidance on future environmental objectives and pollution prevention initiatives. The impact assessment involved examining historical investigative and remediation costs since 1985, types of contaminants, subsurface geology, hydrology, and regulatory requirements. The results reveled that 85% of the historical environmental costs were associated with hexavalent chromium and chlorinated solvents. Other contaminants, such as oils and other petroleum products and other heavy metals, were far more commonly detected but only accounted for the remaining 15% of costs. The results also indicated that the costs are also strongly associated with the type of geologic environment to which the chemicals were released. As a result of these findings, an aggressive pollution prevention program has been initiated to eliminate the use of those contaminants that are especially expensive to remediate and to develop stronger and more effective engineering controls at facilities located in sensitive ecological areas.     

A landscape ecological approach to address scaling problems in conservation management and monitoring

Management of many African game reserves is today often still an art based on experience and intuition, rather than a science. Decision-making is based on an informal integration of accumulated individual knowledge and keen field observations. Data are generally poorly captured and curated. Until fairly recently, denominators of biological parameters (such as the unit of land or unit of plant production used as measurement) have generally been treated as being homogenous. The patchiness of landscapes and the issue of ecological scaling were ignored, often because of a lack of appropriate technical tools. The ecological data available on the 49,000-ha Songimvelo Game Reserve (SGR) result from a number of discrete survey and monitoring projects undertaken by different researchers, with different objectives, at different spatial and temporal scales. A landscape ecological approach towards research and monitoring is appropriate for an area of the size and diversity of the SGR. A combination of a database approach and spatial representation was used to consolidate and integrate data across temporal and spatial scales. Herbivore spatial and temporal distribution patterns were explored across three spatial scales. An understanding was achieved of the importance of landscape patchiness in controlling resource availability for herbivores. This insight is important in guiding management and monitoring of the SGR by placing perceived patch overutilization in its proper landscape context. The landscape ecological approach bridges the traditional scale-independent view to a more contemporary scale-related understanding of ecosystem diversity and functioning.     

Heavy metals in an urban watershed in southeastern Michigan

The occurrence of heavy metals in the soil was measured over a period of several years to determine background concentrations in a heavily urbanized watershed in southeastern Michigan. A spatially dispersed sample was collected to capture the inherent variability of the soils and historic land use. The analysis focused on 14 metals (antimony, arsenic, barium, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, thallium, and zinc) that are part of the USEPA's list of the 129 most common pollutants. Metal concentrations were measured at three depths: near-surface (<0.5 m), shallow subsurface (0.5-10 m), and depths greater than 10 m across six soil units in glacial terrain. Additional analyses assessed the metal concentrations in each depth profile across three general land use categories: residential, commercial, and industrial. Metal concentrations were the highest in the near-surface with Pb present at concentrations averaging 15.5 times that of background in industrial areas and approximately 16 times background in residential areas. Cadmium, Hg, and Zn were also present in surface soils at levels of several times that of background. The highest concentrations of each of these metals were present in the clay-rich soils located in the eastern, more urbanized and industrialized part of the watershed. Metals detected at elevated concentrations decreased in concentration with increasing depth and distance from the urbanized and industrialized center of the watershed. Statistically significant differences in the concentrations of heavy metals were also noted between the land use categories, with Cd, Cr, Cu, Pb, Ni, and Zn observed within industrial areas at mean concentrations several times greater than background levels.     

Incentives for private residential brownfields development in US urban areas

Public agencies in the US have committed resources to encourage private investment in reusing contaminated sites. With public funds in short supply, the effectiveness of their efforts matters both to the agencies and the development community. This paper draws on a mail survey of private developers that uses conjoint choice experiments to investigate the relative attractiveness of incentives to promote residential infill on contaminated property. Results suggest protection from third party liability offers the most value, with protection from cleanup liability and relief from public hearing requirements also important. The findings indicate several opportunities for planners to promote infill on contaminated sites in a socially and environmentally appropriate manner.