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Amphibians often feed on beetle larvae, including those of ground beetles (Carabidae). Preliminary reports have detailed an unusual trophic interaction in which, in contrast, larvae of the ground beetle Epomis prey upon juvenile and adult amphibians. While it is known that these larvae feed exclusively on amphibians, how the predator-prey encounter occurs to the advantage of the beetle larvae had been unknown to date. Using laboratory observations and controlled experiments, we recorded the feeding behavior of Epomis larvae, as well as the behavior of their amphibian prey. Here we reveal that larvae of two species of Epomis (E. circumscriptus and E. dejeani) lure their potential predator, taking advantage of the amphibian's predation behavior. The Epomis larva combines a sit-and-wait strategy with unique movements of its antennae and mandibles to draw the attention of the amphibian to the presence of a potential prey. The intensity of this enticement increases with decreasing distance between the larva and the amphibian. When the amphibian attacks, the larva almost always manages to avoid the predator's protracted tongue, exploiting the opportunity to attach itself to the amphibian's body and initiate feeding. Our findings suggest that the trophic interaction between Epomis larvae and amphibians is one of the only natural cases of obligatory predator-prey role reversal. Moreover, this interaction involves a small insect larva that successfully lures and preys on a larger vertebrate. Such role reversal is exceptional in the animal world, extending our perspective of co-evolution in the arms race between predator and prey, and suggesting that counterattack defense behavior has evolved into predator-prey role reversal.

Salinity is a key abiotic property of inland waters; it has a major influence on biotic communities and is affected by many natural and anthropogenic processes. Salinity of inland waters tends to increase with aridity, and biota of inland waters may have evolved greater salt tolerance in more arid regions. Here we compare the sensitivity of stream macroinvertebrate species to salinity from a relatively wet region in France (Lorraine and Brittany) to that in three relatively arid regions eastern Australia (Victoria, Queensland and Tasmania), South Africa (south-east of the Eastern Cape Province) and Israel using the identical experimental method in all locations. The species whose salinity tolerance was tested, were somewhat more salt tolerant in eastern Australia and South Africa than France, with those in Israel being intermediate. However, by far the greatest source of variation in species sensitivity was between taxonomic groups (Order and Class) and not between the regions. We used a bayesian statistical model to estimate the species sensitivity distributions (SSDs) for salinity in eastern Australia and France adjusting for the assemblages of species in these regions. The assemblage in France was slightly more salinity sensitive than that in eastern Australia. We therefore suggest that regional salinity sensitivity is therefore likely to depend most on the taxonomic composition of respective macroinvertebrate assemblages. On this basis it would be possible to screen rivers globally for risk from salinisation.

Streams and rivers in mediterranean-climate regions (med-rivers) are subjected to sequential, yet contrasting hydrologic disturbances of drying and flooding. Although seasonally predictable, these disturbances can vary in intensity and duration within and among mediterranean-climate regions (med-regions). Consequently, med-rivers differ in the permanence of their aquatic habitats. To persist, species have acquired matched resistance and resilience adaptations. They gain resistance either by enduring the stress or avoiding it. Community recovery (or resilience) is achieved with cessation of hydrologic stress that permits maximization of re-colonization and reproduction. Endurance strategies are usually disturbance-specific, but avoidance enables organisms to cope with both drying and flooding, and is the prevalent resistance strategy. Correspondingly, community persistence depends to a large extent on the integrity of refuges, an aspect that has so far been little explored. Existing information suggests that seasonal community succession becomes more pronounced with increasing aridity and declining water permanence. The invertebrate community in semi-arid med-rivers can therefore undergo succession through three to four identifiable assemblages, whereas in perennial streams the difference between wet and dry period assemblages is smaller. Community turnover is influenced by the intensity of the hydrologic disturbances and varies between wet and drought years.

Biological invasions pose a great threat to the integrity of natural communities. Some invasive species demonstrate a population explosion shortly after arrival while in other cases a prolonged lag between arrival and population outbreak is evident. This paper describes a case of a prolonged lag and explores the possible mechanism for this lag. The Red Sea mussel Brachidontes pharaonis, a Lessepsian migrant, was first recorded in the Mediterranean seven years after the opening of the Suez Canal in 1869. Since then it spread along the Israeli coast and as far northwest as Sicily. Studies conducted in the late 1970s, when B. pharaonis was still rare, predicted that it would not establish dense populations along the Israeli coast and would not outcompete the indigenous mussel Mytilaster minimus, although it has strong negative effects on survival and growth of the native species. It was attributed to the invader's low intrinsic rate of increase relative to that of the native species, and to strong density-independent mortality generated by exposure to high wave action and sedimentation. In contrast to these predictions, we found massive formations of B. pharaonis beds after lag of about 120 years. We looked for distributional patterns that may explain this lag and found no south-north gradient but a strong habitat-dependent colonization. Most apparent are dense B. pharaonis mussel beds (density >300 per 100cm^sup 2^) on rocky platforms where mussel beds were absent in the past. These platforms lack the vermetid rim that is typical to this formation. In platforms protected by a biogenic rim, sediment accumulation is high and perennial algae flourish. None of the mussel species form beds in such habitats. We suggest that the delayed formation of B. pharaonis beds along the Israeli coast is a consequence of a recent shift in habitat conditions on some platforms. It is possible that receding of the biogenic rim at the edge of these platforms allowed more effective washing, reduced sediment accumulation, and reduced perennial algae cover making platforms more suitable for the mussels. Lower density-independent mortality allowed B. pharaonis to dominate on such platforms over the indigenous species. On beachrock, a habitat previously dominated by M. minimus, we recorded a rapid shift in numerical domination to B. pharaonis (from 1:7 to 1.4:1 Brachidontes/Mytilaster individuals) over a period of 4 years (1995-1999). This is probably a result of saturation of the habitat by B. pharaonis recruits originating from the established populations on platforms. Salinity changes and a potential genetic shift may also have contributed to the invasive mussel outbreak.[PUBLICATION ABSTRACT]

The genus Epomis is represented in Israel by two species: Epomis dejeani and Epomis circumscriptus. In the central coastal plain these species are sympatric but do not occur in the same sites. The objective of this study was to record and describe trophic interactions between the adult beetles and amphibian species occurring in the central coastal plain of Israel. Day and night surveys at three sites, as well as controlled laboratory experiments were conducted for studying beetle-amphibian trophic interaction. In the field we recorded three cases of Epomis dejeani preying upon amphibian metamorphs and also found that Epomis adults share shelters with amphibians. Laboratory experiments supported the observations that both Epomis species can prey on amphibians. Predation of the three anuran species (Bufo viridis, Hyla savignyi and Rana bedriagae) and two urodele species (Triturus vittatus and Salamandra salamandra infraimmaculata) is described. Only Epomis dejeani consumed Triturus vittatus. Therefore, we conclude that the two species display a partial overlap in food habit.

Species identification using the characteristics of developmental stages is challenging. However, for insect taxonomy the coloration of larval stages can be an informative feature. The use of live specimens is recommended for this because the color fades in preserved specimens. In this study we examine the possibility of using variation in coloration and color pattern of larvae in order to distinguish between twoground beetlesspecies Epomis dejeani (Dejean, 1831) and Epomis circumscriptus (Duftschmid, 1812). We present an atlas and describe the coloration and body size of the three larval stages of the above species based on live specimens. An identification key is given for the three larval instars of the two Epomis species. The first instar larvae of the two Epomis species can be easily distinguished based on their color. From the second instar on, the variability in coloration and color patterns increases, creating an overlap in these attributes between larvae of the two species. Except for minor differences in color of the antennae and the base of the mandibles, larvae of the two species are indistinguishable at the second and third larval stages. To the best of our knowledge this is the first attempt to use variation in coloration and color pattern in live larvae in order to identify coleopterans. The color atlas of the larvae enables simple separation of the two Epomis species without requiring sophisticated magnifying devices, although it is less straightforward at the second and third larval stages. We found similar body lengths between the two species for all developmental stages, except for third instar larvae prior to pupation. In the two species the difference in larval body length before pupation positively correlated with that of the adult beetles. More than 70% of the adults’ length can be explained by the length of the late third-instar larva; i.e. the large larvae develop into large adults. The larger specimens are the females.

Israel's largest urban stream-the Yarqon-is severely polluted from discharges of poorly treated effluent. Fish kills occur almost regularly. Interactions between habitat conditions and fish assemblage structure were studied in the upper (less disturbed) and central sections of the Yarqon. Average species richness and fish abundance are significantly higher in the upper section than downstream below the effluent discharge points. Fish biomass was higher in the central section, however. Organic load was the only water quality variable that was significantly correlated with fish assemblage variables. A curve fit analysis suggested a threshold of about 10 mg/l BOD, above which most fish avoid polluted habitats. Multidimensional scaling (MDS) analysis of water quality and fish assemblage variables discriminated among central and upper stream sites. A strong overlap between the fish MDS analysis and water quality MDS analysis results was observed, suggesting a strong association between them in the Yarqon.

Amphibians often feed on beetle larvae, including those of ground beetles (Carabidae). Preliminary reports have detailed an unusual trophic interaction in which, in contrast, larvae of the ground beetle Epomis prey upon juvenile and adult amphibians. While it is known that these larvae feed exclusively on amphibians, how the predator-prey encounter occurs to the advantage of the beetle larvae had been unknown to date. Using laboratory observations and controlled experiments, we recorded the feeding behavior of Epomis larvae, as well as the behavior of their amphibian prey. Here we reveal that larvae of two species of Epomis (E. circumscriptus and E. dejeani) lure their potential predator, taking advantage of the amphibian's predation behavior. The Epomis larva combines a sit-and-wait strategy with unique movements of its antennae and mandibles to draw the attention of the amphibian to the presence of a potential prey. The intensity of this enticement increases with decreasing distance between the larva and the amphibian. When the amphibian attacks, the larva almost always manages to avoid the predator's protracted tongue, exploiting the opportunity to attach itself to the amphibian's body and initiate feeding. Our findings suggest that the trophic interaction between Epomis larvae and amphibians is one of the only natural cases of obligatory predator-prey role reversal. Moreover, this interaction involves a small insect larva that successfully lures and preys on a larger vertebrate. Such role reversal is exceptional in the animal world, extending our perspective of co-evolution in the arms race between predator and prey, and suggesting that counterattack defense behavior has evolved into predator-prey role reversal.

Variability in flow as a result of seasonal precipitation patterns is a defining element of streams and rivers in Mediterranean-climate regions of the world and strongly influences the biota of these unique systems. Mediterranean-climate areas include the Mediterranean Basin and parts of Australia, California, Chile, and South Africa. Mediterranean streams and rivers can experience wet winters and consequent floods to severe droughts, when intermittency in otherwise perennial systems can occur. Inter-annual variation in precipitation can include multi-year droughts or consecutive wet years. Spatial variation in patterns of precipitation (rain vs. snow) combined with topographic variability lead to spatial variability in hydrologic patterns that influence populations and communities. Mediterranean streams and rivers are global biodiversity hotspots and are particularly vulnerable to human impacts. Biomonitoring, conservation efforts, and management responses to climate change require approaches that account for spatial and temporal variability (including both intra- and inter-annual). The importance of long-term data sets for understanding and managing these systems highlights the need for sustained and coordinated research efforts in Mediterranean-climate streams and rivers.