Natural selection should favor females that avoid ovipositing where risk of predation is high for their progeny. Despite the large consequences of such oviposition behavior for individual fitness, population dynamics, and community structure, relatively few studies have tested for this behavior. Moreover, these studies have rarely assessed the mode of detection of predators, compared responses in prey species that vary in vulnerability to predators, or tested for the behavior in natural habitats. In an outdoor artificial pool experiment, we tested the oviposition responses of two dipteran species, Culiseta longiareolata (mosquito) and Chironomus riparius (midge), to the hemipteran predator, Notonecta maculata. Both dipteran species have similar life history characteristics, but Culiseta longiareolata larvae are highly vulnerable to predation by Notonecta, while Chironomus riparius larvae are not. As their vulnerabilities would suggest, Culiseta longiareolata, but not Chironomus riparius, strongly avoided ovipositing in pools containing Notonecta. An experiment in natural rock pools assessing oviposition by Culiseta longiareolata in response to Notonecta maculata yielded an oviposition pattern highly consistent with that of the artificial pool experiment. We also demonstrated that the cue for oviposition avoidance by Culiseta longiareolata was a predator-released chemical: Notonecta water (without Notonecta replenishment) repelled oviposition for 8 days. Oviposition avoidance and mode of detection of the predator have important implications for how to assess the true impact of predators and for the use of commercially produced kairomones for mosquito control.

In contrast to the abundance of literature on the relationship between fish assemblages and habitat structure in the upper 30 m of coral reefs, the deeper (> 40 m) parts of coral reefs are rarely studied. We examined changes in reef fish diversity and habitat structure along an increasing depth gradient, including the unknown deep reef. We ran visual and video transects along a substantial depth gradient (0 to 65 m) in the northern Red Sea and extended the known depth distribution for 48 reef species. We found a change in assemblage composition highly correlated to both the depth gradient and a reduction in the abundance of branching corals with depth. The number of reef fish species declined with depth and we also measured a high species turnover as measured by beta diversity (β t , β w ) in the deep reef. This pattern is mainly due to the replacement of the abundant damselfishes in the shallow reef, which prey on zooplankton, by zooplanktivorous sea basses and wrasses in the deep reef. The steep reduction in branching corals, which most damselfishes use for cover, may be the main factor contributing to this change. We found a peak in species richness (alpha diversity) at 30 m, a peak in β w at 50 to 65 m, and peaks in β t at 30 to 50 m and 50 to 65 m. The 30 m depth stratum shows species of both shallow and deep assemblages generating a transition zone with characters of both deep and shallow habitats. The fish assemblage continues to change with depth, and future research will determine if there exists a depth threshold at which the assemblage will stabilize. KEY WORDS: Depth gradient · Deep reef fish · Gulf of Aqaba · Red Sea · Twilight zone Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 371: [253][254][255][256][257][258][259][260][261][262] 2008 Nishihira 2002). Habitat structure and related abiotic parameters have been shown to be some of the main factors structuring fish communities (McGehee 1994, Lara & Gonzalez 1998, Wantiez & Chauvet 2003, Brokovich et al. 2006). In the context of depth gradients, decreased light levels may hinder the ability of mobile organisms to forage (Rickel & Genin 2005), can decrease algae growth rates (Russ 2003) and can modify coral assemblages and resulting habitat structure. Srinivasan (2003) demonstrated that the distribution of some coral reef fishes over different depths is established at and/or soon after settlement, and suggests that factors associated with depth may explain differences in settlement, growth and survival, and warrant further investigation.While scuba diving has enabled researchers to study these patterns in shallow coral reefs with relative ease and safety, deep habitats are still rarely studied in detail because of decreasing bottom times with depth, and the inherent risks of breathing elevated partial pressures of oxygen and nitrogen. The literature now includes a number of studies that use remote video, submersibles and mixed gas diving to study reef communities of fishes, invertebrates a...

Abstract. 1. Most female Culiseta longiareolata (Diptera: Culicidae) avoid ovipositing in pools that contain the predatory backswimmer Notonecta maculata. Such oviposition habitat selection has been suggested to reflect a trade-off between the risk of predation on larvae and potential density-dependent fitness costs. This putative trade-off was examined. In particular, evidence was sought in support of direct female response to local heterogeneity in habitat quality.2. Three habitat types were established using artificial outdoor pools: predator pools, and non-predator pools with either low or high densities of Culiseta larvae. During each experimental night, females were offered one of the three possible pair-wise treatment combinations.3. The majority (%88%) of females oviposited in low-density pools rather than in the predator-or high-density pools. Furthermore, a substantially higher proportion of females oviposited in predator pools when faced with the high-density alternative, however this was due largely to fewer females ovipositing in high-vs low-density pools.4. Females of a second mosquito species (Culex laticinctus), the larvae of which are at a lower risk of predation, were predicted to exhibit weaker aversion to N. maculata; this prediction was supported only weakly.5. Oviposition habitat selection by female C. longiareolata does not appear to involve a behavioural response that is based on individual assessment of local heterogeneity in relative pool quality, at least not at the spatial scale examined here; alternative explanations are discussed.

In plants, the circadian system controls a plethora of processes, many with agronomic importance, such as photosynthesis, photoprotection, stomatal opening, and photoperiodic development, as well as molecular processes, such as gene expression. It has been suggested that modifying circadian rhythms may be a means to manipulate crops to develop improved plants for agriculture. However, there is very little information on how the clock influences the performance of crop plants. We used a noninvasive, high-throughput technique, based on prompt chlorophyll fluorescence, to measure circadian rhythms and demonstrated that the technique works in a range of plants. Using fluorescence, we analyzed circadian rhythms in populations of wild barley (Hordeum vulgare ssp. spontaneum) from widely different ecogeographical locations in the Southern Levant part of the Fertile Crescent, an area with a high proportion of the total genetic variation of wild barley. Our results show that there is variability for circadian traits in the wild barley lines. We observed that circadian period lengths were correlated with temperature and aspect at the sites of origin of the plants, while the amplitudes of the rhythms were correlated with soil composition. Thus, different environmental parameters may exert selection on circadian rhythms.

Large but uneven reduction in fish size across species in relation to changing sea temperatures" (2017). Faculty Publications in the Biological Sciences. 565. http://digitalcommons.unl.edu/bioscifacpub/565 This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/gcb.13688 This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved. AbstractEctotherms often attain smaller body sizes when they develop at higher temperatures. This phenomenon, known as the temperature size rule, has important consequences for global fisheries, whereby ocean warming is predicted to result in smaller fish and reduced biomass.However, the generality of this phenomenon and the mechanisms that drive it in natural populations remain unresolved. In this study we document the maximal size of 74 fish species along a steep temperature gradient in the Mediterranean Sea and find strong support for the temperature size rule. Importantly, we additionally find that size reduction in active fish species is dramatically larger than for more sedentary species. As the temperaturedependence of oxygen consumption depends on activity levels, these findings are consistent This article is protected by copyright. All rights reserved.with the hypothesis that oxygen is a limiting factor shaping the temperature size rule in fishes. These results suggest that ocean warming will result in a sharp, but uneven, reduction in fish size that will cause major shifts in size-dependent interactions. Moreover, warming will have major implications for fisheries as the main species targeted for harvesting willshow the most substantial declines in biomass.

Algae are an essential component of healthy coral reefs and serve as the base of the food chain and as a living habitat for numerous organisms. Herbivorous fish play an important role in coral reef ecology by mediating competition between fast-growing algae and relatively slow-growing corals. However, because of diving-related difficulties, the importance of herbivory in deep mesophotic coral reefs (30 to 150 m) remains largely unknown. We examined the relationship between herbivores and algae along a depth gradient down to 65 m, and evaluated grazing pressure along the depth gradient. We visually assessed the abundance of herbivorous fish along the depth gradient and estimated fish biomass. We measured in situ turf algae growth rates and performed experimental assessments of grazing pressure using settlement plates and bioassays. We discovered that, while both algal growth and fish density decrease with depth, the decrease in grazing pressure is steeper, with a consumption of < 20% of turf-algae production at 65 m versus 40 to 60% at depths of 5 to 20 m. Concomitantly, a decrease in fish biomass and density along the depth gradient reduced potential grazing pressure on macroalgae. Our findings suggest a less important role for herbivorous fish in maintaining algal-free substrate for coral recruitment and growth in deep zones compared with the shallow reef.

We investigated the mechanism underlying oviposition habitat selection (OHS) in the mosquito Culiseta longiareolata. The putative outcome of a trade-off between the risk of predation and detrimental density dependence, OHS in this species presents an opportunity to test two competing alternatives: (1) a polymorphic scenario, in which a fixed proportion of females constantly avoid Ôpredator poolsÕ, while the remainder oviposits at random; and (2) a monomorphic scenario, in which all females oviposit in predator pools with a certain probability. We present a conceptual framework that demonstrates how a simple experimental design -whereby predator incidence in artificial pools is alternated between 0.25 and 0.75 -can distinguish between, or refute, the two scenarios. Given the proportional use, by ovipositing females, of predator-free pools observed under each treatment, and a bootstrap estimate of the ratio of daily oviposition rates, we find the monomorphic scenario twice as likely as the polymorphic.

Sampling issues preclude the direct use of the discovery rate of exotic species as a robust estimate of their rate of introduction. Recently, a method was advanced that allows maximum-likelihood estimation of both the observational probability and the introduction rate from the discovery record. Here, we propose an alternative approach that utilizes the discovery record of native species to control for sampling effort. Implemented in a Bayesian framework using Markov chain Monte Carlo simulations, the approach provides estimates of the rate of introduction of the exotic species, and of additional parameters such as the size of the species pool from which they are drawn. We illustrate the approach using Red Sea fishes recorded in the eastern Mediterranean, after crossing the Suez Canal, and show that the two approaches may lead to different conclusions. The analytical framework is highly flexible and could provide a basis for easy modification to other systems for which first-sighting data on native and introduced species are available.