Toxizität und Risk Assessment fluvialer Sedimente und Schwebstoffe: Eine kurze Übersicht bisheriger und neuerer Entwicklungen

Background In recent years, sediments have become a central topic of scientific and public discussion as an important factor for determining water quality. While the quality of surface waters in Germany has significantly improved during the past years, highly contaminated sediments still create a considerable threat to the quality of several European catchment areas. Main features Here, we summarize different concepts and methods for the assessment of sediment quality and report on some novel integrative test methods for assessing sediment toxicity including contaminant re-mobilization during simulated re-suspension events. Results and discussion Currently, different approaches for assessment of sediment pollution exist. While instrumental chemical analyses are not suitable to accurately describe sediment toxicity, combinations of biological and chemical test procedures and integrated approaches, for example weight-of-evidence studies and effect-directed analysis (EDA), have the potential to identify key contaminants. Inter-disciplinary studies combining hydrodynamic and toxicological aspects coupled to real exposure of aquatic organisms to contaminants are currently being developed. Conclusions Monitoring and assessment of sediment quality are of increasing importance, not only for national legislation but also for the implementation of the European Water Framework Directive (WFD). Integrated approaches for the determination of sediment stability play a key role in the appropriate sediment-monitoring strategies.     

A Contemporary,Sex‐Limited Change in Body Size of an Estuarine Turtle in Response to Commercial Fishing

Abstract: Juvenile growth rate and adult body size are important components of life‐history strategies because of their direct impact on fitness. The diamondback terrapin (Malaclemys terrapin) is a sexually dimorphic, long‐lived turtle inhabiting brackish waters throughout the Atlantic and Gulf coasts of the United States. In parts of its range, terrapins face anthropogenically imposed mortality: juveniles of both sexes inadvertently enter commercial crab traps and drown. For adult females, the carapace eventually grows large enough that they cannot enter traps, whereas males almost never reach that critical size. We compared age structure, carapace dimensions, growth curves, and indices of sexual dimorphism for a Chesapeake Bay population of terrapins (where mortality of turtles is high due to crab traps) with contemporary terrapins from Long Island Sound and museum specimens from Chesapeake Bay (neither group subject to commercial crab traps). We also calculated the allochronic and synchronic rates of evolutionary change (haldanes) for males and females to measure the rate of trait change in a population or between populations, respectively. We found a dramatic shift to a younger male age structure, a decrease in the length of time to terminal female carapace size, a 15% increase in female carapace width, and an increase in sexual dimorphism in Chesapeake Bay. In a new twist, our results implicate a fishery in the selective increase in size of a reptilian bycatch species. These sex‐specific changes in life history and demography have implications for population viability that need to be considered when addressing conservation of this threatened turtle.     

Evolutionary Distinctiveness,Threat Status,and Ecological Oddity in Primates

Abstract: The EDGE (evolutionarily distinct and globally endangered) conservation program ( http://www.edgeofexistence.org ) uses a composite measure of threat and phylogenetic isolation to rank species for conservation attention. Using primates as a test case, we examined how species that rank highly with this metric represent the collective from which they are drawn. We considered the ecological and morphological traits, including body mass, diet, terrestriality, and home range size, of all 233 species of primates. Overall, EDGE score and the level of deviance from the mean of 20 different ecological, reproductive, and morphological variables were correlated (mean correlation r =0.14, combined p =1.7 × 10^?14). Although primates with a high EDGE score had characteristics that made them seem odd, they did not seem to express more ancestral characteristics than expected. Sets of primate species with high EDGE scores will, therefore, collectively capture a broader than expected range of the biology of the clade. If similar patterns hold in other groups, the EDGE metric may be useful for prioritizing biodiversity for conservation.     

Klima-Biomonitoring: Nachweis des Klimawandels und dessen Folgen für die belebte Umwelt

Hintergrund und ZielEs wird vorgeschlagen, Biomonitoring-Verfahren zu verwenden, um Auswirkungen des Klimawandels auf die belebte Umwelt zu erkennen, zu bewerten und zu dokumentieren, weil ? es mit dieser Methode gelingt, klimainduzierte Veränderungen in besonders empfindlichen Gebieten in Deutschland mit ihren Lebensräumen, Lebensgemeinschaften und Arten darzustellen, ? es bezüglich Zuwanderung und Ausbreitung neuer Schädlinge und Krankheitserreger für Mensch, Tier und Pflanze nach bzw. in Deutschland relevante Informationen liefern kann, ? damit der Politik zur Bewertung der Auswirkungen des Klimawandels wichtige Informationen, Handreichungen und Entscheidungsgrundlagen zur Verfügung gestellt werden können und ? auf dieser Grundlage geeignete Anpassungsmaßnahmen eingeleitet und auf ihre Wirksamkeit geprüft werden können, wie beispielsweise in der Deutschen Anpassungsstrategie (BMU 2009) beschrieben. Für Biomonitoring-Verfahren, die geeignet sind, Auswirkungen des Klimawandels anzuzeigen, wird der Begriff Klima-Biomonitoring vorgeschlagen Diese Verfahren sollten aus verschiedenen Gründen (u.?a. abgestimmte Methodik und gleiche Datenbasis, Kostenersparnis) unter Beteiligung aller Bundesländer umgesetzt werden. Bioindikation ist bereits heute ein unverzichtbares Verfahren, frühzeitig Veränderungen in der belebten Umwelt zu erkennen und somit Hinweise auf besondere Gefahren zu liefern (Frühwarnsystem). Für das Klima-Biomonitoring werden vorzugsweise bestehende Monitoringsysteme mit ihren bereits erhobenen Daten ausgewertet und mitgenutzt. Material und Methoden Das Klima-Biomonitoring greift auf bereits eingeführte und bewährte Methoden der Bioindikation von Umweltveränderungen zurück. Bestehende Methoden werden im Hinblick auf die besonderen, durch den Klimawandel bedingten Anforderungen ergänzt, angepasst und weiterentwickelt. Auf der Grundlage einer Auswertung relevanter laufender Bundes- und Länderprogramme werden wesentliche Wirkungen des Klimawandels identifiziert, die datenliefernden Programme zugeordnet und Auswertungen vorgeschlagen. Zusätzlich werden Datenquellen beschrieben, deren Nutzung weitergehende Betrachtungen ermöglichen. ErgebnisseIn einer Übersichtstabelle werden Monitoring-Programme auf Bundes- und Länderebene systematisiert und hinsichtlich ihrer Bedeutung für die Bewertung von Klimafolgen auf die belebte Umwelt dargestellt. Eine Übersicht über Datenquellen sowie eine Darstellung erster Erkenntnisse aus der Auswertung vorliegender Daten belegen die Relevanz des vorgeschlagenen Verfahrens. Der erkennbare Forschungs- und Entwicklungsbedarf wird umrissen und Vorschläge für eine Optimierung des Daten- und Methodenaustausches benannt. Beispiele zur Anwendung und Vertiefung der Thematik sowie Anregungen zur Weiterentwicklung der Methodik und zum Schließen von Kenntnislücken werden in Folgepublikationen aufgezeigt. DiskussionAuf der Basis des Klima-Biomonitorings kann das Ausmaß der durch den Klimawandel bereits eingetretenen Veränderungen beschrieben sowie Szenarien und Prognosen zu den Auswirkungen von Klimaveränderungen erstellt werden. Weiterhin ist es möglich, die sekundären Wirkungen des Klimawandels, insbesondere die Auswirkungen der Maßnahmen zur Anpassung an den Wandel, mithilfe der Bioindikation auf ihre Wirksamkeit zu prüfen. Für einige Klima-Bioindikatoren ist der kausale Zusammenhang zwischen Klimawandel und Reaktion bereits belegt (zum Beispiel die Frühjahrsphasen in der Pflanzenphänologie), in anderen Fällen müssen noch Methoden zur Unterscheidung zwischen Klimawirkungen und anderen Wirkfaktoren entwickelt werden. Die Erkenntnisse aus dem Klima-Biomonitoring sollen Grundlage für entsprechende Handlungen sein, sodass geeignete Anpassungsstrategien und gleichzeitig Maßnahmen zur Vermeidung oder zur Verminderung der Effekte eingeleitet werden können. Zugleich sollen eine angemessene Politikberatung, eine Information der Öffentlichkeit und die Erfüllung entsprechender Berichtspflichten erfolgen. Schlussfolgerungen:Klima-Biomonitoring ist eine geeignete Methode, um klimainduzierte Veränderungen in besonders empfindlichen Gebieten in Deutschland mit ihren Lebensräumen, Lebensgemeinschaften und Arten darzustellen. Erste Auswertungen zeigen, dass bereits Wirkungen des Klimawandels auf die belebte Umwelt nachweisbar sind. Hierbei liefert die Pflanzenphänologie seit vielen Jahren wertvolle Hintergrunddaten. Eine Verschneidung dieser Hintergrunddaten mit Daten aus anderen geeigneten Monitoring-Programmen und weiteren Informationen (zum Beispiel Geobasisdaten) ermöglicht es, diese Erkenntnisse zu ergänzen. Damit ist die Ermittlung und Bewertung von klimainduzierten Wirkungen auch im Bereich der Ausbreitung von Krankheitsüberträgern und -erregern und anderer Phänomene sowie der Bewertung von Maßnahmen möglich. Empfehlungen und PerspektivenEine abgestimmte Anwendung der Methodik in allen Bundesländern und beim Bund, eine Verbesserung des Daten- und Methodenaustausches, die Identifikation, Erschließung und Nutzung weiterer Datenquellen, die Weiterentwicklung der Methodik und eine Publikation weiterer Erkenntnisse werden empfohlen. Es ist davon auszugehen, dass sich das Klima-Biomonitoring wegen seiner Vorteile als Methode zur Erhebung von Klimafolgen für die belebte Umwelt auch international etablieren wird.     

Offspring sex ratios reflect lack of repayment by auxiliary males in a cooperatively breeding passerine

The repayment hypothesis posits that primary sex ratios in cooperative species should be biased towards the helping sex because these offspring “repay” a portion of their cost through helping behavior and therefore are less expensive to produce. However, many cooperatively breeding birds and mammals do not show the predicted bias in the primary sex ratio. Recent theoretical work has suggested that the repayment hypothesis should only hold when females gain a large fitness advantage from the presence of auxiliary adults in the group. When auxiliaries provide little or no fitness advantage, competition between relatives should lead to sex ratios biased towards the dispersing (non-helping) sex. We examined the benefits auxiliaries provide to females and corresponding offspring sex ratios in the red-backed fairy-wren (Malurus melanocephalus), a cooperatively breeding Australian bird with male auxiliary helpers. We found that auxiliaries provide little or no benefit to female reproductive success or survival. As predicted, the population primary sex ratio was biased towards daughters, the dispersing sex, and females with auxiliaries produced female-biased broods whereas females without auxiliaries produced unbiased broods. Moreover, offspring sex ratios were more strongly biased toward females in years when auxiliaries were more common in the population. These results suggest that offspring sex ratios are associated with competition among the non-dispersing sex in this species, and also that females may use cues to assess local breeding opportunities for their offspring.     

Kleptoparasites: a twofold cost of group living for the colonial spider, Metepeira incrassata (Araneae, Araneidae)

Several species of kleptoparasitic and araneophagic spiders (Araneae: Family Theridiidae, Subfamily Argyrodinae) are found in colonial webs of the orb-weaving spider Metepeira incrassata (Araneae, Araneidae) from Mexico, where they steal food and/or prey upon their spider hosts. Census data from natural M. incrassata colonies reveal that the incidence of these species increases with colony size. This pattern may reflect the presence of several other orb-weaving spiders, each with their own kleptoparasitic species, invading larger M. incrassata colonies. As the number of these associated spiders increases, so does the density and number of Argyrodinae species in M. incrassata colonies, suggesting that associated spiders might reduce their own kleptoparasite load by building their webs within M. incrassata colonies. This represents a twofold cost to M. incrassata, as a field enclosure experiment revealed that a primarily kleptoparasitic species (Argyrodes elevatus) may reduce prey available to their hosts, but a kleptoparasitic/araneophagic species (Neospintharus concisus) inflicts high mortality upon M. incrassata. However, the cost of kleptoparasitism and predation by these species may be offset in part for M. incrassata individuals in large colonies by certain defensive mechanisms inherent in groups, i.e., “attack-abatement” and “selfish herd” effects. We conclude that increased occurrence of kleptoparasitic and/or predatory Argyrodinae spiders is a consequence of colonial web building and is an important potential cost of group living for colonial web-building spiders.     

PULSE,progressive upper level set scan statistic for geospatial hotspot detection

This paper presents a scan statistic, progressive upper level set (PULSE) scan statistic, for geospatial hotspot detection and its software implementation. Like ULS, the PULSE scan statistic is based on the arbitrarily shaped scan window and can be adapted for a network setting. PULSE is a refinement of the upper level set (ULS) scan statistic. Like some other likelihood based scanning devices, the ULS scan statistic identifies maximum likelihood estimate (MLE) zones that tend to be ‘stringy’ and sprawling. Its search path increases possibility of inclusion of extraneous cells in its MLE zones and, to a smaller extent, of exclusion of cells that belong to a true hotspot from its MLE zone. The PULSE scan statistic achieves improvement over the ULS scan statistic in two ways. First, it begins its search for a most likely zone with a large population of candidate zones obtained by modifying the ULS tree structure and continues its search using a genetic algorithm. Secondly, to reduce chances of generating an MLE that is excessively stringy and that includes extraneous cells in the MLE zone, PULSE uses cardinality and compactness of zones along with their likelihoods as the fitness function in the genetic algorithm and uses several pertinent criteria including evenness of intra-zone cellular response ratios to determine the MLE zone. To reduce computation, Gumbel distribution of extreme values is used to determine the p-value of the MLE zone. Better results come at the cost of increased processing time. An evaluative performance study is presented.     

Behavioural inertia places a top marine predator at risk from environmental change in the Benguela upwelling system

In variable environments, organisms are bound to track environmental changes if they are to survive. Most marine mammals and seabirds are colonial, central-place foragers with long-term breeding-site fidelity. When confronted with environmental change, such species are potentially constrained in their ability to respond to these changes. For example, if environmental conditions deteriorate within their limited foraging range, long-lived species favour adult survival and abandon their current breeding effort, which ultimately influences population dynamics. Should poor conditions persist over several seasons, breeding-site fidelity may force animals to continue breeding in low-quality habitats instead of emigrating towards more profitable grounds. We assessed the behavioural response of a site-faithful central-place forager, the Cape gannet Morus capensis, endemic to the Benguela upwelling system, to a rapid shift in the distribution and abundance of its preferred prey, small pelagic shoaling fish. We studied the distribution and the abundance of prey species, and the diet, foraging distribution, foraging effort, energy requirements, and breeding success of gannets at Malgas Island (South Africa) over four consecutive breeding seasons. Facing a rapid depletion of preferred food within their foraging range, Cape gannets initially increased their foraging effort in search of their natural prey. However, as pelagic fish became progressively scarcer, breeding birds resorted to scavenging readily available discards from a nearby demersal fishery. Their chicks cannot survive on such a diet, and during our 4-year study, numbers of breeding birds at the colony decreased by 40% and breeding success of the remaining birds was very low. Such behavioural inflexibility caused numbers of Cape gannets breeding in Namibia to crash by 95% following over-fishing of pelagic fish in the 1970s. In the context of rapid environmental changes, breeding-site fidelity of long-lived species may increase the risk of local or even global extinction, rendering these species particularly vulnerable to global change.     

Sampling animal association networks with the gambit of the group

Ecologists increasingly use network theory to examine animal association patterns. The gambit of the group (GoG) is a simple and useful assumption for accumulating the data necessary for a network analysis. The gambit of the group implies that each animal in a group is associating with every other individual in that group. Sampling is an important issue for networks in wild populations collected assuming GoG. Due to time, effort, and resource constraints and the difficulty of tracking animals, sampled data are usually a subset of the actual network. Ecologists often use association indexes to calculate the frequency of associations between individuals. These indexes are often transformed by applying a filter to produce a binary network. We explore GoG sampling using model networks. We examine assortment at the level of the group by a single dichotomous trait, along with many other network measures, to examine the effect of different sampling regimes, and choice of filter on the accuracy and precision with which measures are estimated. We find strong support for the use of weighted, rather than filtered, network measures and show that different filters have different effects depending on the nature of the sampling. We make several practical recommendations for ecologists planning GoG sampling.