Toxic effects of endocrine disrupters on freshwater sponges: common developmental abnormalities

Endocrine disrupters are of substantial concern, in large part because effects of these compounds on the growth and development of many aquatic organisms are unknown. We examined toxic effects of three substances (ethylbenzene, nonylphenol, and bisphenol A), that are known to be hormonally active in many animals, on growth and development of two species of freshwater sponge. A common developmental abnormality was observed when sponges were treated with each of these compounds. The three compounds also caused significant reductions in growth rates. Lower concentrations resulted in malformed water vascular systems in several replicates. The utility of freshwater sponge bioassays is discussed as it relates to understanding possible mechanisms of action of endocrine disrupters on aquatic invertebrates.     

Raumbezug und Repr?sentativit?t in der ?kologischen Fl?chenstichprobe

Zusammenfassung  Die Qualit?t von Raumgliederungen kann letztlich nur vor dem Hintergrund des jeweiligen Verwendungskontextes beurteilt werden. Im Bereich der Umweltbeobachtung kommt Raumgliederungen neben ihrer Nutzung zu Analysezwecken inbesondere im Hinblick auf Auswahlverfahren von Untersuchungsfl?chen gro?e Bedeutung zu. Der Beitrag erl?utert den Zusammenhang von Raumgliederung, Auswahlverfahren und Repr?sentativit?t am Beispiel der ?kologischen Fl?chenstichprobe (?FS) und stellt die Gliederung vor, die im Rahmen einer ?FS-Pilotstudie getestet wurde. Online-First: 19. Mai 2000     

Forest floor depth mediates understory vigor in xeric Pinus palustris ecosystems.

Longleaf pine (Pinus palustris) woodlands and savannas are among the most frequently burned ecosystems in the world with fire return intervals of 1-10 years. This fire regime has maintained high levels of biodiversity in terms of both species richness and endemism. Land use changes have reduced the area of this ecosystem by >95%, and inadequate fire frequencies threaten many of the remnants today. In the absence of frequent fire, rapid colonization of hardwoods and shrubs occurs, and a broad-leaved midstory develops. This midstory encroachment has been the focus of much research and management concern, largely based on the assumption that the midstory reduces understory plant diversity through direction competition via light interception. The general application of this mechanism of degradation is questionable, however, because midstory density, leaf area, and hardwood species composition vary substantially along a soil moisture gradient from mesic to extremely xeric sites. Reanalysis of recently reported data from xeric longleaf pine communities suggests that the development of the forest floor, a less conspicuous change in forest structure, might cause a decline in plant biodiversity when forests remain unburned. We report here a test of the interactions among fire, litter accumulation, forest floor development, and midstory canopy density on understory plant diversity. Structural equation modeling showed that within xeric sites, forest floor development was the primary factor explaining decreased biodiversity. The only effects of midstory development on biodiversity were those mediated through forest floor development. Boundary line analysis of functional guilds of understory plants showed sensitivity to even minor development of the forest floor in the absence of fire. These results challenge the prevailing management paradigm and suggest that within xeric longleaf pine communities, the primary focus of managed fire regime should be directed toward the restoration of forest floor characteristics rather than the introduction of high-intensity fires used to regulate midstory structure.     

Possible control mechanism of cell motility in the gorgonian Eunicella cavolinii

In a previous study it was demonstrated that a lectin controls cell-cell interaction in the gorgonian Eunicella cavolinii (Koch) as a negative modulator. Now we describe the procedure to purify this lectin to homogeneity; its molecular weight is 23 400. The homologous proteoglycans were identified as positive modulators of cell-cell (and/or cell substrate) interaction. The purified single proteoglycan aggregates were 1200±700 nm long and the distance between the attachment points of the proteoglycan subunits was about 45 nm. The glycosaminoglycan residues of the gorgonian proteoglycans were identified as hyaluronic acid (35.5%), heparan sulfate (47.9%) and dermatan sulfate (14.1%). Binding studies with immobilized homologous proteoglycan preparations revealed that gorgonian cells attach to this substratum presumably via its glycosaminoglycans. Quantitative determinations of these two modulators of cell-cell recognition in the three regions of individual colonies revealed concentration gradients these concentration differences reflect a lower cell motility in the polyp-bearing branches and a higher motility of the cells in the polyp-free stem and in the basis, is discussed.     

The Arctic in an earth system context: from brake to accelerator of change

Human activities over the past few centuries have profoundly changed the functioning of the earth system as a whole. These changes are particularly evident in the high latitudes of the Northern Hemisphere, where environmental change has been pronounced and rapid. Such changes have implications beyond the region, as they can lead to two important feedback processes: the ice-albedo feedback and the terrestrial carbon cycle-climate feedback. These processes play an exceptionally important role in earth system functioning, particularly because they may switch this century from damping the effects of anthropogenic climate change to accelerating them. Rapid environmental change in the high latitudes also has consequences for issues of direct importance to humans, particularly water resources.     

Increasing the safety of children's vehicle travel: from effective risk communication to behavior change

INTRODUCTION: When installed and used correctly, child safety seats reduce the risk of fatal injury by 71% for infants and 54% for toddlers. However, four out of five safety seats are unintentionally misused. Yet, parents fail to participate in safety-seat checks and other child seat interventions aimed at correcting misuse. METHOD: Such lack of participation is the focus of this article, which argues that most caregivers are na?ve to their own vulnerability for misusing their child's seat. Research on risk perception is discussed as a guide to understanding both the high misuse rate and the lack of participation in interventions designed to correct this public safety problem. RESULTS AND IMPACT: A comprehensive intervention plan that incorporates risk communication techniques for maximum parental participation is proposed that includes three essential components: (a) establishing community locations for parents to turn for safety seat advice, (b) making these locations well known to the public, and (c) increasing caregivers' perceptions of risk of misusing their children's seats.     

Beneficial use of dredged material for habitat creation, enhancement, and restoration in New York-New Jersey Harbor

A comprehensive Dredged Material Management Plan (DMMP) has been developed by the US Army Corps of Engineers, New York District (USACE-NYD) and the Port Authority of New York and New Jersey (PANY/NJ). The primary objective of the DMMP is to identify cost-effective and environmentally acceptable alternatives for the placement of dredged material derived from ongoing and proposed navigation improvements within the PANY/NJ. A significant portion of this dredged material is classified as unsuitable for open-ocean disposal. One suite of alternatives presented within the DMMP is the beneficial use of dredged material for habitat creation, enhancement, and restoration within the NY/NJ Harbor Estuary. Proposed beneficial use/habitat development projects include the use of dredged material for construction of artificial reefs, oyster reef restoration, intertidal wetland and mudflat creation, bathymetric recontouring, filling dead-end canals/basins, creation of bird/wildlife islands, and landfill/brownfields reclamation. Preliminary screening of the proposed beneficial use alternatives identified advantages, disadvantages, potential volumes, and estimated costs associated with each project type. Continued study of the proposed beneficial use alternatives has identified areas of environmental research or technology development where further investigation is warranted.