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The Levantine Basin at the south-eastern corner of the Mediterranean represents the trailing edge of the distribution of native Atlanto-Mediterranean species, where they are exposed to the most extreme temperature and salinity conditions. The region is also fast warming and exposed to a flood of alien species, mostly thermophilic ones from the Indo-Pacific. The Levant coast also hosts a unique, fragile and understudied rocky intertidal ecosystem – vermetid reefs. Anecdotal historical data and observations, and recent extensive intertidal and shallow subtidal community surveys on the Israeli coast (including a marine reserve) indicate that Levant reefs are (1) overfished; (2) highly invaded by thermophilic alien species, some (rabbitfish) highly destructive; (3) dominated by turf barrens (canopy-forming brown algae are rare, probably overgrazed by rabbitfish) and increasing patches of alien algae and (4) suffering the loss of many native species (e.g., urchins subtidally and the main reef-building vermetid gastropod, Dendropoma petraeum, intertidally). Laboratory work has shown that many native species that are still abundant are likely to disappear under increasing warming, while aliens are much more resistant. Mesocosm experiments demonstrated that, under both warming and acidification, the community structure will further shift, and whole community functions will transform from autotrophic to heterotrophic.
The ‘deep sea’ encompasses a broad range of habitats that differ greatly in their assemblages and ecosystem functioning. Habitats may be described by a combination of environmental factors (e.g., depth, slope) and biotic factors (e.g., source of primary productivity). We review recent attempts to define deep-sea biogeographic provinces based on spatial and temporal variations in oceanographic conditions, and consider potential boundaries to distributional ranges, in particular habitats based on recent phylogeographic studies. We briefly discuss abiotic interactions in various habitats, noting the particular influence of local hydrodynamics. We consider competition and predation at whale falls and hydrothermal vents, discuss symbiotic interactions particularly with respect to deep-sea corals, which are particularly prevalent in submarine canyons and seamounts, and consider the difficulties of inferring processes from patterns.
We summarise processes determining large-scale patterns of distribution and abundance of macroinfauna from Florida to Newfoundland, ~25°N to 52°N, focussing on intertidal and shallow subtidal (~ 5 m depth) muddy sands and sandy muds, habitats with abundant experimental data. Within the theme of geographic distribution of processes, mechanisms and patterns we suggest latitudinal patterns will likely change most as climate changes intensify. Published studies support the following major biogeographic patterns: (1) reduced importance of large disturbance predators north of Cape Cod, driven by latitudinal shifts in thermal regimes; (2) large digging predators from Delaware Bay (39.25°N) southwards dramatically reduce infaunal densities, restricting competitive interactions; (3) disturbance refugia, e.g., Zostera, drive southern spatial patterns; (4) rising seawater temperatures and reduced water clarity limit the extent and diversity of rooted plants in the south and mid-Atlantic; (5) latitudinal changes in tidal regimes result in greater aerial exposure in the north, magnifying latitudinal sea surface temperature changes; (6) ice cover intensifies to the north and (7) the Boston−Washington, DC megalopolis accentuates human signatures through eutrophication between 36.5°N and 42.6°N. Finally, we discuss potential shifts with climate change in these latitudinal patterns and processes.
Carnivore conservation depends on people's willingness to implement management practices to reduce threats to carnivores and mitigate conflicts between carnivores and domestic animals. We assessed the willingness of rural communities in central-southern Chile to (1) conserve carnivores, and (2) adopt management practices to reduce predation of domestic animals, a key factor triggering carnivore–human conflicts in rural areas. The study focused on five carnivores: the chilla Lycalopex griseus, the culpeo Lycalopex culpaeus, Darwin's fox Lycalopex fulvipes, the guiña or kodkod Leopardus guigna, and the puma Puma concolor. We found that rural communities perceived that threats towards carnivores rarely occurr in their region, contrary to the literature on this subject; people's attitudes differed depending on the carnivore; and people were willing to adopt management practices to help conserve carnivores (e.g. overnight protection of domestic animals and investment in infrastructure for henhouses and cowsheds), except leashing dogs. The willingness to conserve carnivores and adopt practices that would help do so may be associated with how these measures affect people's well-being. Although rural communities would like carnivores to be conserved, this cannot be achieved unless some pivotal practices, such as management of domestic dogs, are adopted by these communities. For successful biodiversity conservation outcomes in human-dominated landscapes, the social incentives necessary for rural communities to adopt appropriate management practices must be identified and implemented.
Local attitudes towards carnivores often reflect the degree of damage they are perceived to cause. Consequently, understanding the interactions between people and these species is essential to conservation efforts. This study investigated local perceptions of three Cerrado canid species and current chicken management practices, to identify the potential damage they cause and how this relates to peoples’ attitudes towards these species. Results from structured interviews at 50 ranches in Goiás, Brazil, highlighted that general knowledge about Cerrado canids differed significantly by species, with interviewees unable to correctly answer questions about the hoary fox Lycalopex vetulus and crab-eating fox Cerdocyon thous in comparison to the maned wolf Chrysocyon brachyurus. Chicken coops were identified as the most effective method for preventing predation, yet only 44% of respondents employed this method. Using a perceived predation measure, interviewees reported chicken predation by all three Cerrado canids even though most of these events were stated to occur during the day, outside the species’ active periods. Reported predation events were a strong predictor of attitude. Participants who experienced predation events reported they did not like having a Cerrado canid on their property. However, 86% of the respondents agreed that Cerrado canids should nevertheless be protected. Our findings support the need to incorporate the human dimension in canid and broader carnivore conservation issues.
The number of non-indigenous aquatic species (NIS) has rapidly increased globally. The majority of published evidence on the effects of NIS on local communities is from single species studies in which the interactive effects of NIS are not considered. Here we present experimental evidence of separate and interactive effects of two widespread non-indigenous benthic predators, the round goby (Neogobius melanostomus) and the North American mud crab (Rhithropanopeus harrisii) on benthic invertebrate communities in a shallow coastal ecosystem of the Gulf of Riga, the Baltic Sea. The two species have recently colonized multiple sub-basins of the Baltic Sea and due to their rapid range expansion, increasing densities and local functional novelty, they are expected to have strong separate or interactive effects on native communities. Our laboratory experiment demonstrated that round goby and mud crab exerted a significant predation pressure on different benthic invertebrate species and the effects of the studied predators were largely independent. Predation was stronger at higher temperature compared with low temperature treatment. Among the studied invertebrate species gammarid amphipods were consumed the most. Interestingly, round goby did not prey on the mud crabs despite a large size difference of the studied predators.
Extinctions have altered island ecosystems throughout the late Quaternary. Here, we review the main historic drivers of extinctions on islands, patterns in extinction chronologies between islands, and the potential for restoring ecosystems through reintroducing extirpated species. While some extinctions have been caused by climatic and environmental change, most have been caused by anthropogenic impacts. We propose a general model to describe patterns in these anthropogenic island extinctions. Hunting, habitat loss and the introduction of invasive predators accompanied prehistoric settlement and caused declines of endemic island species. Later settlement by European colonists brought further land development, a different suite of predators and new drivers, leading to more extinctions. Extinctions alter ecological networks, causing ripple effects for islands through the loss of ecosystem processes, functions and interactions between species. Reintroduction of extirpated species can help restore ecosystem function and processes, and can be guided by palaeoecology. However, reintroduction projects must also consider the cultural, social and economic needs of humans now inhabiting the islands and ensure resilience against future environmental and climate change.
In parasites with complex life cycles the transmission of free-living infective stages can be influenced by ambient community diversity, in particular via predation. Here, we experimentally investigated whether parasite density and the presence of alternative prey can alter predation rates on free-living cercarial stages of a marine trematode by several non-host predators. All four predator species consumed increasing numbers of cercariae with an increase in cercarial density, indicating that the removal of cercariae by predators is effective over a range of natural densities as well as in the presence of alternative prey for a number of predators typical of marine ecosystems. However, the relative removal rates and the effects of cercarial density and alternative prey differed among predator species. In barnacles and shrimps, significant interactive effects of cercarial density and alternative prey on cercarial predation occurred while in oysters and crabs cercarial removal rates were unaffected by both factors. As changes in cercarial densities directly translate into changes in infection levels in down-stream hosts in this parasite–host system, the observed predator-specific responses suggest that cercarial predation effects on disease risks will depend on the specific species composition of ambient communities and not on non-host biodiversity per se.
A Lagrangian study was conducted in a eutrophic estuary (Guanabara Bay, Brazil) to investigate in situ plankton trophodynamics under the influence of the cold, nutrient-rich South Atlantic Coastal Water in a short-term temporal variability (scale of hours). We tested the hypothesis that the base of the plankton food web is composed of small cells and that microzooplankton is the main consumer of this assemblage. Samples of pico-, nano- and microplankton, as well as copepods, were collected during spring, when the entry of upwelling water in the Bay is commonly observed, and near the surface every 3 h during the 1-day sampling period. Potential predation of dinoflagellates, ciliates, copepod nauplii, copepodites and adult copepods was estimated based on predator-prey size relationships. The main trophic links in the Guanabara Bay food web for the period analysed were nanophytoplankton-copepods, nanophytoplankton-ciliates, and autotrophic dinoflagellates-heterotrophic dinoflagellates. According to microphytoplankton availability, adult copepods could not satisfy their food requirement, and nanophytoplankton represented an important supplementary food source. In fact, diel variations of nano- and microplankton biomass were opposite to that of copepods suggesting predation control by the latter on the former. The trophodynamics of Guanabara Bay, under the influence of upwelling water, resulted in marked differences from other eutrophic estuaries around the world.
Livestock depredation has particular significance in pastoral societies across the Himalayas. The dynamics of depredation by the snow leopard Panthera uncia and wolf Canis lupus were investigated by means of household surveys in the Hushey Valley, in the Karakoram Mountains of Pakistan. During 2008–2012 90% of the households in the valley lost livestock to snow leopards and wolves, accounting for 0.8 animals per household per year. The cost of depredation per household was equivalent to PKR 9,853 (USD 101), or 10% of the mean annual cash income. The majority (41%) of predation incidents occurred in summer pastures, predominantly at night in open spaces. Of the total number of predation incidents, 60% were attributed to snow leopards and 37% to wolves; in 3% of cases the predator was unknown. As an immediate response to predation the majority of the local people (64%, n = 99) opted to report the case to their Village Conservation Committee for compensation and only 1% preferred to kill the predator; 32% did not respond to predation incidents. The perceived causes of predation were poor guarding (77%), reduction in wild prey (13%), and livestock being the favourite food of predators (10%). The most preferred strategies for predator management, according to the respondents, were enhanced guarding of livestock (72%), followed by increasing the availability of wild prey (18%), and lethal control (10%). Livestock depredation causing economic loss may lead to retaliatory killing of threatened predators. For carnivore conservation and livestock security in this area we recommend improved livestock guarding through collective hiring of skilled shepherds and the use of guard dogs.
Cet article traite de l'exclusion par manipulation des marchés de permis d'émission. Dans un premier temps, nous déterminons la valeur de l'exclusion que le permis représente. Puis, nous définissons la stratégie de surachat des permis et évaluons son impact sur le prix du permis. Nous en tirons alors un certain nombre de conclusions en termes de dotations initiales et de politique économique, après avoir illustré ces résultats par une application numérique.
The study analyses the role of non-indigenous invertebrates in the food webs of two eutrophic brackish estuarine ecosystems of the Baltic Sea: the Neva River estuary and the Curonian Lagoon, with the aim of clarifying several questions such as what trophic levels were occupied by newly established species (mainly amphipods and mysids) and whether they can affect the native benthic invertebrates as a result of their possible carnivorous nature. Stable isotope analysis (δ15N values) and gut contents analysis of field-collected specimens were used to estimate trophic level and trophic links of the newly established malacostracan crustaceans, while their consumption rates when feeding as carnivores were measured experimentally. The δ15N analysis allocated four trophic levels (TL) in the coastal food webs of both studied ecosystems with the lowest δ15N (2–4‰) for detritus and algae and the highest for fish (12–14‰). Through their high abundance, non-indigenous crustaceans (Pontogammarus robustoides, Gmelinoides fasciatus, Obessogammarus crassus, Gammarus tigrinus, Limnomysis benedeni and Paramysis lacustris) have become important members of food chains of the studied ecosystems. Their trophic position varied significantly within species during ontogenesis. This suggests that they turned from being typically detritivores/plantivorous (TL 2–2.4) at juvenile stages to omnivores (2.5–3) or to carnivores (>3) as adults. Assessment of the predation pressure by the adult amphipods on other coexisting invertebrates (in the example of the Neva Estuary) showed a low or medium impact, depending on species of predator and productivity of its potential prey organisms.
Shark bite marks on mosasaur bones abound in the fossil record. Here we review examples from Kansas (USA) and the Maastrichtian type area (SE Netherlands, NE Belgium), and discuss whether they represent scavenging and/or predation. Some bite marks are most likely the result of scavenging. On the other hand, evidence of healing and the presence of a shark tooth in an infected abscess confirm that sharks also actively hunted living mosasaurs.
The DR Congo embarked upon decentralization reforms in 2006 to improve governance and accountability, undermine predation, corruption, and personal rule, bring government closer to the people, and promote local development. As of 2014, despite some regional variations, Congolese decentralization had instead increased the degree to which the state extracts the resources and incomes of its citizens. It had also fostered provincial centralization at the expense of local governments, produced largely unaccountable provinces governing with little transparency, and unleashed self-serving provincial elites. After providing original empirical evidence for these claims, this article suggests that decentralization was thwarted by the failure of formal reforms to affect informal ruling institutions and by an erroneous diagnosis of Congo’s governance failures that singled out the abuse of elites without identifying the generalized nature of the instrumentalization of sovereignty by officeholders at all levels of the state. The article concludes by using Congo’s experience to illustrate important flaws in decentralization reforms in Africa.
Population decline resulting from agricultural intensification led to contraction of the range of the cirl bunting Emberiza cirlus in the UK to a small area of south Devon. As part of the UK Biodiversity Action Plan for the species, a project to re-establish a population in suitable habitat in Cornwall was undertaken during 2006–2011, in which chicks were removed from the nest in Devon, hand-reared and then delayed-released. The survival of the birds to four time points in the year after release was analysed in relation to the effect of rearing factors, using a multivariable logistic regression model. Individuals with higher body weight at capture were more likely to survive to 1 January and 1 May in the year following release, and individuals released in June and July were more likely to survive than those released in August. Individuals released in 2006 and 2011 had a higher survival rate than those released during 2007–2010. Timing of capture, time spent at each stage in captivity, medication and the detection of parasites in the brood had no significant effect. Immunosuppressive disease, weather factors and predator activity may have led to some of the observed differences in survival. This analysis provides evidence with which to plan future translocation projects for cirl buntings and other passerine birds.
Polinices marambioensis is a naticid gastropod which is the most common constituent in fossil accumulations in the upper section of the Cucullaea I Allomember (Middle Eocene) of the La Meseta Formation in James Ross Basin, Antarctic Peninsula. This species was an important predator of infaunal bivalves and gastropods, including other naticids. The aim of this work was to assess the pattern of predation and cannibalistic behaviour of P. marambioensis. A total of 2648 specimens of P. marambioensis were examined for drill holes, which were assigned to Oichnus paraboloides. Drilling frequency data were measured as a proxy for predation intensity and statistical analyses were performed. Further, the site of each drill hole was established according to the morphological features of the shell on each specimen to assess possible preference of predators for the site of perforation. Results suggest that P. marambioensis is an efficient cannibalistic predator for a specific size range of prey (8–22 mm), and drill holes are distributed preferentially in two specific sectors of their shells. This selective cannibalistic prey behaviour in P. marambioensis affected not only the dynamics of their populations but the ecological structure of the community in which they lived.
In the 1980s, penguins dominated the prey remains of sub-Antarctic skuas Stercorarius antarcticus breeding on Marion Island, whereas on neighbouring Prince Edward Island burrowing petrels made up >95% of prey remains in nest middens. This difference resulted at least in part from the impact of introduced cats Felis catus on Marion Island’s burrowing petrel populations. Cats were introduced to Marion Island in 1949, and prior to their eradication in 1991, they killed an estimated 450 000 petrels each year, greatly reducing the densities of petrels breeding on the island. A repeat survey of skua prey remains showed that penguins still dominated the prey of breeding sub-Antarctic skuas on Marion Island in the summer of 2010–11, two decades after cats were eradicated from the island. The proportion of penguin remains decreased slightly compared to 1987–88, but this might be expected given the decreases in penguin numbers on Marion Island over this period. Regurgitated pellets confirmed the dominance of penguin prey on Marion Island. Taken together with the decrease in skua numbers on Marion Island over the last two decades, our results suggest that there has been little recovery in the population of at least summer-breeding burrowing petrels since cats were eradicated.
Studies on insect natural enemies and their effects on host populations are of immense practical value in pest management. Predation and parasitism on a citrus pest, the leafminer Phyllocnistis citrella Stainton, were evaluated by sampling over 3 years in four locations within a world leading lemon producing area in Northwest Argentina. Both mortality factors showed seasonal trends consistent across locations, with predation exerting earlier and more sustained pressure than parasitism, which showed wider seasonal variations. The dominant parasitoids, native Cirrospilus neotropicus and introduced Ageniaspis citricola, showed different seasonal trends: C. neotropicus was dominant in spring whereas A. citricola superseded it in autumn and winter. Although parasitism rates were relatively low, the native C. neotropicus revealed favourable features as potential control agent, by showing density-dependence, parasitism rates comparable with those of the specific A. citricola during part of the cycle, and earlier synchronization with the host. The study provides highly relevant information for a sustainable management of this worldwide pest, for which biological control is considered the best long-term option.
The study of the feeding habits of elasmobranch populations should help to elucidate the ecological role of these fishes in the marine ecosystem. Feeding habits of the apron ray, Discopyge tschudii from San Jorge Gulf were investigated. An evaluation of whether the diet of D. tschudii changes with body size, seasons, maturity stage and sex was performed using a multiple-hypothesis modelling approach. Discopyge tschudii preyed mainly on polychaetes. The consumption of polychaetes was higher in males. Also, amphipods and siphons of clams were preyed more heavily in the cold season and Munida gregaria in the warm season. Stomatopods were consumed more with increasing body size. All prey categories were independent of maturity stage. We concluded that D. tschudii is a benthic feeder.
Aglajidae is a family of tropical and temperate marine Cephalaspidea gastropod slugs regarded as active predators. In order to better understand their food habits and trophic interactions, we have studied the diet of all genera through the examination of gut contents. Specimens were dissected for the digestive tract and gut contents were removed and identified by optical and scanning electron microscopy. Our results confirmed that carnivory is the only feeding mode in aglajids and showed a sharp preference for vagile prey (94% of food items). We suggest that the interaction between crawling speed, presence of sensorial structures capable of detecting chemical signals from prey, and unique features of the digestive system (e.g. lack of radula, eversion of the buccal bulb, thickening of gizzard walls) led aglajid slugs to occupy a unique trophic niche among cephalaspideans, supporting the hypothesis that dietary specialization played a major role in the adaptive radiation of Cephalaspidea gastropods.