UV-Filtersubstanzen in Wasser und Fischen

A method was developed for the analysis of fish samples to detect sunscreen agents (SSA) together with organochlorides (PCB, DDT) in different fish tissues. Detection limits of the compounds analyzed are in the range of ng/kg and vary between 40 and 90 ng/kg fillet. Recovery rates range from 78 to 104%. The contamination of water and fish with SSA in Meerfelder Maar lake, the Eifel, Germany was investigated in 1991 and 1993 and allowed the identification and quantification of six different SSA in the fish. The sum of SSA concentrations in perch taken in the summer of 1991 was 2.0 mg/kg lipid and 0.50 mg/kg lipid was found in roach sampled during the summer of 1993. Both species were contaminated with SSA and organochlorides to the same ranges as PCB and DDT. Even in the fillet of roach taken from three other lakes in Germany, methylbenzylidene camphor, a lipophilic SSA, was detected. These results indicate that SSA are wide-spread in German lakes. Therefore, they can be seen as a new group of relevant environmental chemicals. In the investigated lakes, the concentrations of the SSA in water were mostly below the detection limits. Thus, fish can be used as a biomonitor for these lipophilic compounds. Due to the lack of toxicological data for aquatic organisms, an ecotoxicological assessment is impossible at the moment.     

Interactive effects of natural and human disturbances on vegetation dynamics across landscapes.

Accurate measures of human effects on landscape processes require consideration of both the direct impacts from human activities and the indirect consequences of the interactions between humans and the landscape. This is particularly evident in systems experiencing regular natural disturbances such as in the mountainous areas of southwestern China, where the remaining population of giant pandas (Ailuropoda melanoleuca) is supported. Here the spatiotemporal patterns of human impacts, forests, and bamboo episodic die-offs combine to determine the distribution of panda habitat. To study the complex interactions of humans and landscapes, we developed an integrated spatiotemporally explicit model of household activities, natural vegetation dynamics, and their impacts on panda habitat. Using this model we examined the direct consequences of local fuelwood collection and household creation on areas of critical giant panda habitat and the indirect impacts when coupled with vegetation dynamics. Through simulations, we found that over the next 30 years household impacts would result in the loss of up to 30% of the habitat relied on by pandas during past bamboo die-offs. The accumulation and spatial distribution of household impacts would also have a considerable indirect influence on the spatial distribution of understory bamboo. While human impacts influence both bamboo die-off and regeneration, over 19% of pre-existing low-elevation bamboo habitat may be lost following an episodic die-off depending on the severity of the impacts and timing of the die-offs. Our study showed not only the importance of the spatial distribution of direct household impacts on habitat, but also the far-reaching effects of the indirect interactions between humans and the landscapes they are modifying.     

Toxicity and attraction effects produced byMorinda citrifolia fruits on theDrosophila melanogaster complex of species

Summary The ripe fruit of the Indian mulberry,Morinda citrifolia, is the host plant forDrosophila sechellia but is highly toxic for three closely related species (D. melanogaster, D. simulans, D. mauritiana). A simple bioassay is described with which a clear dose response to the fruit was found for these species. Significant differences in reactivity to the ripe fruit were found among species. Tested strains ofD. simulans andD. mauritiana adults were more sensitive to the toxic properties of the fruit thanD. melanogaster. A marked intraspecific variability was shown inD. melanogaster. Reciprocal interspecific hybridizations betweenD. sechellia andD. mauritiana suggested an autosomal dominant control of resistance. MoreoverD. melanogaster intraspecific crossings suggested the influence of an additional X-linked factor. Responses of flies toMorinda fruit in different states were tested in a T olfactometer. The less resistant strains ofDrosophila generally showed less preference for the ripe fruit.     

Mitochondrial DNA Variability of the Gray Wolf: Genetic Consequences of Population Decline and Habitat Fragmentation

The gray wolf is a large, highly mobile predator whose original geographic range included most of the Northern Hemisphere. High rates of genetic exchange probably characterized even distantly-separated populations in the past, but recent population declines and habitat fragmentation have isolated previously contiguous populations, especially in the Old World. We examine mitochondrial DNA (mtDNA) variability among twenty-six populations of wolves from throughout their geographic range. We find eighteen mtDNA genotypes in gray wolves, seven of these are derived from hybridization with coyotes, four are confined to the New World, six are confined to the Old World and one is shared by both areas. Genetic differentiation among wolf populations is significant but small in magnitude. In the Old World, most localities have a single unique genotype, whereas in the New World several genotypes occur at most localities and three of the five genotypes are nearly ubiquitous. The pattern of genetic differentiation in the gray wolf contrasts with that of another large, highly vagile canid, the coyote, in which genetic differentiation among populations is not significant even among widely separated localities. We suggest that the difference between these two species reflects the rapid, recent increase in coyote numbers and expansion of their geographic range, and the coincident decline in gray wolf populations. Apparent genetic differences among extant wolf populations may be a recent phenomenon reflecting population declines and habitat fragmentation rather than a long history of genetic isolation.     

Analysis of chromium and copper by cathodic stripping voltammetry with mixed ligands

Cathodic adsorptive stripping voltammetry is one of the most sensitive analytical methods for ultratrace analysis. The detection limit is usually lower than 10⁻⁹ mol/L. Most adsorptive stripping procedures have been focused on the one ligand/one analyte approach. In order to reduce analysis time and sample volume, the possibility of simultaneously determining several metals by cathodic stripping voltammetry using a mixture of ligands was explored, e.g., by Colombo and van den Berg (1997). Here, we describe a new procedure for quantifying chromium and copper using 2,2′-bipyridine and 8-hydroxyquinoline (oxine). The effect of various operational parameters such as buffer type, ligand concentration, potential and time collection were assessed and optimized. Possible interferences by trace metals and organic matter were also investigated. Applicability for fresh water is illustrated. Electronic Publication     

Effects of different levels of song overlapping on singing behaviour in male territorial nightingales (Luscinia megarhynchos)

In signalling interactions, animals can directly address information to a specific individual. Vocal overlapping is such a signalling strategy used in songbirds, anurans, and insects. In songbirds, numerous studies using high rates of song overlap to simulate an escalating situation have shown that song overlapping is perceived as a threatening signal by interacting and by listening (eavesdropping) individuals, indicating a high social relevance of song overlapping. Here we present a playback experiment on nocturnally singing male territorial nightingales (Luscinia megarhynchos). Using three different rates of song overlap (1, 25, or 50%), we tested whether or not lower levels of song overlapping act as a signal of aggressive intent and if birds would increase the intensity of their response with increasing level of song overlapping. Subjects did not vary song duration in response to the different playback treatments but increasingly interrupted their singing with increasing overlap by the three playback treatments. The effects persisted even after the playback ceased to overlap and switched to an alternating singing mode. These results expand on previous studies by showing that song overlapping is interpreted as an aggressive signal even when it is used at low or moderate levels. They suggest that, within the range tested here, increasing levels of song overlapping are perceived to be increasingly aggressive.     

Differences in acoustic directionality among vocalizations of the male red-winged blackbird (<Emphasis Type="Italic">Agelaius pheoniceus</Emphasis>) are related to function in communication

Studies of animal acoustic communication have found that the frequency and temporal structure of acoustic signals can be shaped by selection for efficient communication. The directionality of acoustic radiation may also be adapted for communication, but we know relatively little about how directionality varies with signal function, sender morphology, and the environment in which the sound is transmitted. We tested the hypothesis that the directionality of a vocalization is adapted to its function in communication. This hypothesis predicts that vocalizations that are directed to multiple conspecifics (e.g., advertisements and alarms) will be relatively omnidirectional because this will maximize the number of neighbors and mates that receive the signal, and that vocalizations directed to particular individuals will be relatively directional because this will maximize detection of the signal by the targeted receiver and minimize eavesdropping. To test these predictions, we measured the directionality and amplitude of red-winged blackbird (Agelaius pheoniceus) vocalizations in the field by recording vocalizations simultaneously on eight calibrated microphones encircling the bird. We found significant variation in directionality among vocalizations. Supporting our predictions, we found that the most omnidirectional vocalizations were those used to alert conspecifics to danger, and the most directional vocalizations are those used during courtship and solicitation of copulation, when the costs of eavesdropping are likely to be high. These results suggest that the directionality of red-winged blackbird vocalizations is shaped by selection for effective communication. This study is the first to provide statistical support for the hypothesis that directionality is related to the function of a signal in communication.     

Algal “gardening” behavior by nereid polychaetes: Effects on soft-bottom community structure

Nereid polychaetes (Nereis vexillosa and Platynereis bicanaliculata) attach pieces of drift algae to their tube surfaces. The presence of permanent algal cover increases the predictability of the food supply for at least the herbivores (including the nereids) and the deposit feeders, and modulates the temperature and salinity stresses of the marine intertidal soft-bottom environment. However, it may affect the access of organisms to the oxygenated water layers above the sediment surface. This is true for polychaetes that live head downwards in vertical tubes. It is suggested that the attachment behavior of the nereid polychaetes increases the ability of the plant to colonize habitats both temporally and spatially.     

Evaluating Management of Protected Areas: Integrating Planning and Evaluation

/ An approach to evaluating the effectiveness of management of protected areas is proposed. This approach has been used in developing an evaluation strategy for the Fraser Island World Heritage Area in Australia. The main component of the strategy is built upon the desired outcomes specified in the management plan for the area and thus provides a basis for assessing the extent to which the plan's objectives are being achieved. A series of monitoring programs have been proposed to enable this assessment. Examples of monitoring programs developed as part of the evaluation strategy are presented. A second component of the strategy monitors the implementation of the management plan. A management information system has been developed to record and report on the extent to which the specific actions specified in the management plan have been implemented. The strategy is discussed in relation to seven objectives set for the evaluation program in its design phase.KEY WORDS: Planning; Evaluation; Monitoring; Management; Protected areas     

An Integrated Model of Public Contact Planning for Conservation Management

/ Public contact is a vital component of any program to manage natural resources. A well-planned public contact program uses a variety of strategies to create a sympathetic and environmentally aware public and to meet specific management-related objectives. A methodology is proposed that can be applied to planning public contact at any level, from media design for a specific project to corporate strategies for communication. The methodology integrates management-driven, client-driven and resource-driven planning to provide the connections essential to effective communication.KEY WORDS: Planning; Public contact; Interpretation; Conservation; Management