Effects of the dinoflagellates Karlodinium veneficum and Prorocentrum minimum on early life history stages of the eastern oyster (Crassostrea virginica)

The bloom-forming dinoflagellates Prorocentrum minimum and Karlodinium veneficum can have detrimental effects on some marine life, including shellfish, but little is known about their effects on early life history stages of bivalves. In the Chesapeake Bay region, blooms of these dinoflagellates overlap with the spawning season of the eastern oyster, Crassostrea virginica. In laboratory experiments, we compared the effects of P. minimum and K. veneficum on the survival and development of embryos and larvae of the eastern oyster. At 10⁴ cells ml⁻¹, P. minimum did not have a negative effect on embryos and larvae in 2-day exposures. The yield of D-hinge larvae was equal to or greater than in control treatments. At 2 × 10⁴ cells ml⁻¹ (approximately equal biomass to the P. minimum treatment) K. veneficum caused significant mortality to oyster embryos within 1 day and almost no embryos developed into D-hinge larvae. This effect was not alleviated by the provision of an alternate food source (Isochrysis sp.). Significant mortality was observed when larvae were exposed to K. veneficum at concentrations of 10⁴ cells ml⁻¹ (approximately 5 ng ml⁻¹ of karlotoxin). The K. veneficum cultures used in these experiments were relatively low in toxin content, more toxic strains could be expected to cause mortality at lower cell concentrations. Survival and maturation of embryos and larvae may be reduced when spawns of the eastern oyster coincide with high bloom densities of K. veneficum.     

Copper sulphate (CuSO4) toxicity on tissue phosphatases activity and carbohydrates turnover in Achatina fulica

A time course study on the sublethal toxicity of CuSO4 on tissue carbohydrate metabolites level and their phosphatases activity in Achatina fulica revealed differential response. The levels of total carbohydrates and glycogen in the body mass muscle, foot muscle and hemolymph revealed their involvement in the endogenous derivation of energy during stress. The same metabolites in digestive gland revealed its importance to reproduction and development. The lactate accumulated in all the tissues implied the mechanism of CuSO4 toxicosis in the metabolic acidosis. The decrease of pyruvate in foot muscle, body mass muscle and hemolymph inferred the preponderance of glycolysis in energy derivation. In contrast, the pyruvate concentration in digestive gland revealed its differential response in the stress metabolic sequence of changes, as a unique tissue. The lactate/pyruvate ratio and the calcium content in tissues constitute direct evidences for the snails adaptation to toxic stress.     

Orientation ofRhizophagus grandis (Coleoptera: Rhizophagidae) to oxygenated monoterpenes in a species-specific predator-prey relationship

Summary The predator,Rhizophagus grandis, is linked to its specific prey,Dendroctonus micans, by semiochemical signals regulating oviposition and long range orientation. A mixture of simple oxygenated monoterpenes [(–)—fenchone, (–)—pinocamphone, rac. camphor, terpinene-4-ol, borneol, fenchol and verbenone], identified from the frass ofD. micans has been found to be extremely active in a flight windtunnel as a long—range attractant for the predator. The mixture elicited 84 % of the response to larval frass of the prey. Excluding pinocamphone from the mixture did not influence its activity. Also, changing the absolute configurations of some of the components (fenchol, terpinene-4-ol and borneol) did not influence the predators' response. However, the addition of (–)—-terpineol increased the attractivity of the synthetic blend to almost that of larval frass of the prey. Ecological implications of the identified semiochemicals and their use in pest management are discussed.     

Using a Bayesian network to clarify areas requiring research in a host–pathogen system

Bayesian network analyses can be used to interactively change the strength of effect of variables in a model to explore complex relationships in new ways. In doing so, they allow one to identify influential nodes that are not well studied empirically so that future research can be prioritized. We identified relationships in host and pathogen biology to examine disease‐driven declines of amphibians associated with amphibian chytrid fungus (Batrachochytrium dendrobatidis). We constructed a Bayesian network consisting of behavioral, genetic, physiological, and environmental variables that influence disease and used them to predict host population trends. We varied the impacts of specific variables in the model to reveal factors with the most influence on host population trend. The behavior of the nodes (the way in which the variables probabilistically responded to changes in states of the parents, which are the nodes or variables that directly influenced them in the graphical model) was consistent with published results. The frog population had a 49% probability of decline when all states were set at their original values, and this probability increased when body temperatures were cold, the immune system was not suppressing infection, and the ambient environment was conducive to growth of B. dendrobatidis. These findings suggest the construction of our model reflected the complex relationships characteristic of host–pathogen interactions. Changes to climatic variables alone did not strongly influence the probability of population decline, which suggests that climate interacts with other factors such as the capacity of the frog immune system to suppress disease. Changes to the adaptive immune system and disease reservoirs had a large effect on the population trend, but there was little empirical information available for model construction. Our model inputs can be used as a base to examine other systems, and our results show that such analyses are useful tools for reviewing existing literature, identifying links poorly supported by evidence, and understanding complexities in emerging infectious‐disease systems.     

Reagenzienfreie Bestimmung von Quecksilberspuren in Wasserproben

A comprehensive ecological monitoring of hazardous substances is indispensable to preserve our health and environment. Therefore, fast and inexpensive techniques for routine analysis of pollutants are essential. However, in the measuring procedure itself often toxic reagents are used producing hazardous waste. Omitting environmentally hazardous substances in the analysis procedure is an important contribution to a more sustainable and green analytical chemistry. A reagent-free method for ultra-trace (pg to ng?L^-1) mercury determination in water samples was developed and validated. An active nanogold collector integrated in a fully automated flow injection system is the core of this new method. All mercury species dissolved in the water sample are adsorbed and preconcentrated on the nano-structured gold surface of the collector. After rinsing and drying of the collector, the enriched mercury is thermally desorbed and finally measured by atomic fluorescence spectrometry. This method was optimized and validated for the determination of mercury in natural waters. The influence of various water constituents was investigated and only high contents of dissolved organic carbon (DOC) showed interferences of mercury preconcentration due to the strong complexation of mercury by DOC. This restriction can be solved by UV-irradiation, i.?e. reagent-free digestion of DOC rich samples prior to the preconcentration procedure. Mercury concentration of several natural river and sea waters and water from the discharge of a waste water treatment plant were determined with this new analytical method. Accuracy and precision of the method were demonstrated by several recovery experiments in natural water samples (recoveries: 96–102?%) and by analysis of the certified reference material BCR-579 (Mercury in Coastal Sea Water; recovery: 101?±?1?%). With a detection limit of only 80?pg?Hg?L^–1 the proposed method is highly sensitive. Furthermore the method avoids potential contamination of the sample by reagent addition and is due to the reagent-free procedure environment-friendly. Hence this work is an important contribution to sustainable environmental analysis and at the same time improves accurate routine mercury trace analysis.     

The Value of Biodiversity in Reserve Selection: Representation, Species Weighting, and Benefit Functions

Abstract:  The limited availability of resources for conservation has led to the development of many quantitative methods for selecting reserves that aim to maximize the biodiversity value of reserve networks. In published analyses, species are often considered equal, although some are in much greater need of protection than others. Furthermore, representation is usually treated as a threshold: a species is either represented or not, but varying levels of representation over or under a given target level are not valued differently. We propose that a higher representation level should also have higher value. We introduce a framework for reserve selection that includes species weights and benefit functions for under- and overrepresentation (number of locations for each species). We applied the method to conservation planning for herb-rich forests in southern Finland. Our use of benefit functions and weighting changed the identity of about 50% of the selected sites at different funding levels and improved the representation of rare and threatened species. We also identified a small area of additional land that would substantially enhance the existing reserve network. We suggest that benefit functions and species weighting should be considered as standard options in reserve-selection applications.     

Genetic Variation of Naturally Colonizing Wolves in the Central Rocky Mountains

Recovery of gray wolf ( Canis lupus ) populations in North America depends on minimizing human-caused mortality and enhancing migration from stable source populations to suitable habitat unoccupied by wolves. We used a combination of field observation and DNA microsatellite genotyping to examine natural wolf colonization of Glacier National Park, Montana, and surrounding lands. We found high genetic variation in the colonizing population, showing that these packs were founded by multiple, unrelated wolves from Canada. High dispersal rates, long dispersal distances, and lack of a founding population bottleneck indicate that wolves in the United States and Canada should be viewed and managed as a single population. Restoration in the United States by artificial transplants from Alberta to Yellowstone National Park and central Idaho began in 1995. The transplanted wolves will likely aid demographic recovery, but permanently retaining the high genetic variation of wolves in the United States will require assuring gene flow throughout the central Rocky Mountains.     

Population structure and sex-change in the coral-inhabiting snailCoralliophila violacea at Hsiao-Liuchiu,Taiwan

Surveys of the coral-inhabiting snailCoralliophila violacea (Lamarck) (=C. neritoidea Kiener) were made on shallow fringing reefs (<8 m deep) around Hsiao-Liuchiu, Taiwan, between July and October 1990. The snails were aggregated into patches on the surface of massive poritid coral colonies. Coral colonies >40 cm in diameter were more likely to bear patches of snails than smaller colonies, and also to have more snails. The coralliophilids ranged from 5 to 30 mm in aperture length. The sex ratio of the population was biased toward males (539:279), with only a few small individuals of indistinguishable sex. Snails between 6 and 10 mm were all males, while most snails with aperture lengths 20 mm were females. Judging from the distinct size ranges of males and females within patches and from the observed degeneration of the penis, the snails may have changed sex from male to female with increasing size. Sex-change may occur across a wide size range (10 to 20 mm). The correlation of smallest female size and largest male size among patches indicates that snail size at sex-change is peculiar to each individual patch. Those females in patches with a single female (but many males) were significantly smaller than females in multiple-female patches. It is likely that in the absence of females males change sex at a smaller size, whereas in the presence of large females males delay sexchange until they have reached a larger size. The plasticity of size at sex-change may be adaptive and a result of natural selection at the individual level.     

Proposal of Indicators to Assess Urban Sustainability in Brazil

The research related here focuses on municipal situations where problems of sustainability may be defined and tackled on the basis of bottom-up management procedures with the participation of organized society. The aim is to build management models that may be implemented with reasonable administrative effort and cost. Implementation pursues the target of approaching a sustainable situation in the municipality. Environmental parameters for an ideal municipality with undefined geographical location are presented. For each parameter, a set of indicators is developed that can measure the prospect of sustainability. The indicators are defined in terms of numbers or literal concepts according to the possibility of measurement. Examples of management models are presented, which are able to approach the situation defined as sustainable by the indicators. The basic management tool is the learning curve of targeted communities, which is experimentally developed and applied. The indicators are grouped according to their range of applicability.