Biodiversity of coastal polyclad flatworm assemblages in the wider Caribbean

Polyclads are mobile predators and possibly an important functional component of hard substrate marine environments globally. To understand the natural patterns of spatial differences, polyclad assemblages were sampled in seven coastal regions across the wider Caribbean spanning 15° latitude and 24° longitude between May and June 2005 and May and September 2006. In total, 67 species in 28 genera and 17 families were recorded from 62 sites. Only two species were found in all surveyed regions, Melloplana ferruginea and Pseudoceros bicolor. Conversely, 41 species were restricted to one or two sites, and 34 species were represented by one or two individuals. The distribution and abundance of species varied between the two suborders. Cotyleans were most species rich and had a higher number of species of restricted range, while Acotylea showed a higher proportion of rare species; however, two species were highly abundant comprising over half of the individuals counted. In most habitats, polyclads were rare, but in some intertidal habitats two species, Styloplanocera fasciata and Boninia divae were densely aggregated and dominant members of the benthic epifauna. Alpha diversity was variable but showed no evidence of a relationship with latitude, longitude or depth. Beta diversity increased with the number of habitats sampled and was highest for cotyleans. Highest gamma diversity was recorded in Jamaica and the US Virgin Islands and was not significantly correlated to alpha diversity. Overall assemblages from the seven regions were similar, revealing faunal homogeneity across the wider region. Reef assemblages were distinct from other habitats dominated by species of the Cotylea. Reefs from Panama and the US Virgin Islands were the most species rich. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The effects of landscape structure on space competition and alternative stable states

Many species that compete for space live on heterogeneous landscapes and interact at local scales. The quality, amount, and structure of landscapes may have considerable impact on the ability of species to compete or coexist, yet basic models of space competition do not include that level of detail. We model space competition between two species with positive feedback through recruitment facilitation, which creates the potential for alternative stable states to occur. We compare the predictions of a spatially implicit model with a simulation model that includes explicit space and landscape structure. We create structured landscapes in which we specify the amount of habitat and degree of fragmentation and ask how landscape structure, dispersal strategy, and scale affect the presence of alternative stable states, or bistability. We find that structured landscapes can reduce the range of parameter values that lead to bistability in our model, but they do not eliminate bistability. The type of landscape and the dispersal distance for each species also influence the amount of environmental change needed for abrupt community shifts to occur. Coexistence of the two competitors is possible under certain conditions when connectivity is low. Consequently, landscape structure may lead to considerable disparity between the predictions of simple models and actual dynamics on complex landscapes during environmental change.     

Do birds behave according to dynamic risk assessment theory? A feeder experiment

Pair-wise preference experiments were used to reveal predator discrimination by four tit species wintering in the Czech Republic. The reactions of the tits to a more dangerous predator (sparrowhawk) and a less dangerous (kestrel) one were compared. The number of visits to a feeder with a predator present expressed the perceived dangerousness of the predator. The tits' behaviour towards the feeders was in agreement with predictions, according to dynamic risk assessment theory. The presence of any predator at the feeder lowered the number of visits to the feeder. Similarly, the tits were judged to have evaluated the sparrowhawk as being more dangerous than the kestrel, as its presence lowered the number of arrivals more than did the kestrel. The duration of stay and number of pecks of individual birds were also used as measures of predator dangerousness. The results not only confirm that tits behave according to dynamic risk assessment theory, but also show the exceptional suitability of preference experiments for the research of predator differentiation and evaluation.     

The role of positive affectivity in team effectiveness during crises

Organizational efforts to improve team effectiveness in crisis situations primarily have focused on team training initiatives and, to a lesser degree, on staffing teams with respect to members' ability, experience, and functional backgrounds. Largely neglected in these efforts is the emotional component of crises and, correspondingly, the notion of staffing teams with consideration for their affective makeup. To address this void, we examined the impact of team member dispositional positive affect (PA) on team crisis effectiveness and the role of felt negative emotion in transmitting that influence. A study of 21 nuclear power plant crews engaged in crisis training simulations revealed that homogeneity in PA, but not mean‐level PA, was associated with greater team effectiveness. Mediation analysis suggested that homogeneity in PA leads to greater team effectiveness by reducing the amount of negative emotions that team members experience during crises. Furthermore, homogeneity in PA compensated for lower mean‐level PA in predicting effectiveness. Discussion focuses on the implications of these findings for understanding and further exploring the importance of affective factors and especially team affective composition in team crisis performance. Copyright © 2012 John Wiley & Sons, Ltd.     

Featured Collection Introduction: Connectivity of Streams and Wetlands to Downstream Waters

Connectivity is a fundamental but highly dynamic property of watersheds. Variability in the types and degrees of aquatic ecosystem connectivity presents challenges for researchers and managers seeking to accurately quantify its effects on critical hydrologic, biogeochemical, and biological processes. However, protecting natural gradients of connectivity is key to protecting the range of ecosystem services that aquatic ecosystems provide. In this featured collection, we review the available evidence on connections and functions by which streams and wetlands affect the integrity of downstream waters such as large rivers, lakes, reservoirs, and estuaries. The reviews in this collection focus on the types of waters whose protections under the U.S. Clean Water Act have been called into question by U.S. Supreme Court cases. We synthesize 40+ years of research on longitudinal, lateral, and vertical fluxes of energy, material, and biota between aquatic ecosystems included within the Act's frame of reference. Many questions about the roles of streams and wetlands in sustaining downstream water integrity can be answered from currently available literature, and emerging research is rapidly closing data gaps with exciting new insights into aquatic connectivity and function at local, watershed, and regional scales. Synthesis of foundational and emerging research is needed to support science‐based efforts to provide safe, reliable sources of fresh water for present and future generations.     

Water and the politics of sustainability transitions: from regime actor conflicts to system governance organizations

This study contributes to the analysis of the politics of sustainability transitions by developing a focus on regime actor conflicts and a processual model for how these conflicts develop and are resolved. In a comparison of water-supply systems in four U.S. cities, we show how conflicts among regime actors and political jurisdictions lead to the formation of system governance organizations (SGOs) that bridge jurisdictional boundaries to manage conflicts over a technological system (TS). SGOs coordinate relations among water utilities and diverse stakeholders to reduce pervasive conflicts, but they can also serve as drivers of improved sustainability. We analyze resistance that can emerge, such as from urban growth coalitions, which limit the capacity of SGOs to drive changes. We develop a four-stage processual model (first-order regime conflicts, SGO formation, sustainability transition expansion, and second-order regime conflicts) that opens research in the politics of transitions to the dynamic of regime actor conflicts and provides the basis for generalizations about the causes of SGO formation and their effects on the governance of TSs such as water-supply infrastructure. Policy implications regarding how to improve political support for SGO sustainability efforts are also discussed.     

Modelling the effects of UV radiation on the survival of Antarctic krill (Euphausia superba Dana) in the face of limited data

Antarctic krill, Euphausia superba, is a keystone species of the Antarctic ecosystem. A fishery for krill may compete with land-based predators (penguins and seals), particularly during the breeding season. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is moving towards management in small scale units. The management models specify predation and fishing mortality as space and time dependent but do not yet include non-predation natural mortality. Krill are known to be highly susceptible to ultraviolet radiation (UV) but there are limited empirical data. We develop a model for krill mortality caused by UV and parameterize and assess it by comparison with experimental data. The analysis allows us to identify key parameters that should be measured in future experiments and also leads to suggestions about modification of experimental procedure. We illustrate the method for krill found in the Livingston Island area and show that (a) it is possible to estimate the component of natural mortality due to UV-induced damage and (b) that cohorts born in 1979, 1984, or 1997 have different survival in the first 5 years of life, associated with differential UV exposure. In particular, those born in 1997 may have experienced as much as 10% lower survival than those born in 1979. The method developed here allows a potentially important source of krill mortality to be incorporated into the management models and suggests key experiments and field work in the future.     

Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands.