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. 2015. Portfolio theory as a management tool to guide conservation and restoration of multi-stock fish populations. Ecosphere 6(12):296. http://dx.doi.org/10.1890/ES15-00237.1Abstract. Habitat degradation and harvest have upset the natural buffering mechanism (i.e., portfolio effects) of many large-scale multi-stock fisheries by reducing spawning stock diversity that is vital for generating population stability and resilience. The application of portfolio theory offers a means to guide management activities by quantifying the importance of multi-stock dynamics and suggesting conservation and restoration strategies to improve naturally occurring portfolio effects. Our application of portfolio theory to Lake Erie Sander vitreus (walleye), a large population that is supported by riverine and open-lake reef spawning stocks, has shown that portfolio effects generated by annual inter-stock larval fish production are currently suboptimal when compared to potential buffering capacity. Reduced production from riverine stocks has resulted in a single open-lake reef stock dominating larval production, and in turn, high inter-annual recruitment variability during recent years. Our analyses have shown (1) a weak average correlation between annual river and reef larval production (q ¼ 0.24), suggesting that a natural buffering capacity exists in the population, and (2) expanded annual production of larvae (potential recruits) from riverine stocks could stabilize the fishery by dampening inter-annual recruitment variation. Ultimately, our results demonstrate how portfolio theory can be used to quantify the importance of spawning stock diversity and guide management on ecologically relevant scales (i.e., spawning stocks) leading to greater stability and resilience of multi-stock populations and fisheries.

Summary 1.While the antipredator behaviour of prey has been well studied, little is known about the rules governing the predation risk assessment of prey. In this study, I measured the activity levels of predator-naive green frog ( Rana clamitans ) tadpoles during and after exposures to the chemical cue of predatory larval dragonflies ( Anax spp.). I then used the lengths of the time lags from the end of the cue exposures until the tadpoles returned to a control level of activity as an index of the perceived risk of the tadpoles. 2. While tadpoles always responded upon exposure to the Anax chemical cue by strongly reducing their activity level, their perceived risk increased asymptotically over time during the initial period of the cue exposure. Tadpoles of all size classes perceived increasing risk in proportion to chemical cue concentration, but the length of time that tadpoles responded during cue exposure and the length of their post-exposure time lags decreased with increasing body mass. 3. The results suggest that the perceived risk of green frog tadpoles varies over time and does not correspond directly to their behavioural response (i.e. activity level). However, their perceived risk does appear to vary in accordance with the predation risk associated with the Anax chemical cue and the reliability of the information from the cue, and therefore may be predictable.

Ammannia baccifera Linn. is commonly used as a traditional medicine in India and China. The antioxidant potential of an ethanolic extract of A. baccifera (EEAB; 250 mg/kg and 500 mg/kg) was evaluated against CCL4-induced toxicity in rats. Antioxidant activity was assessed by measuring the enzymatic and non-enzymatic antioxidants. Phytochemical constituents of EEAB were also analyzed by using UHPLC-QTOF-MS. EEAB treatment markedly reduced CCl4 effects on lipid peroxidation, cholesterol, triacylglycerides, and protein carbonyls. It increased the levels of phospholipids, total sulfhydryl, and antioxidant enzymes, which were reduced by CCl4 intoxication. Treatment with EEAB significantly alleviated the CCl4 effect on non-enzymatic antioxidants. Isoenzyme pattern analyses revealed that significant alterations in superoxide dismutase (SOD1), glutathione peroxidase (GPx2, GPx3), and catalase (CAT) occurred in rats that were exposed to CCl4 and restored post EEAB treatment. Moreover, CCl4-induced down regulation of SOD, CAT, and GPx gene expression was conversely counteracted by EEAB. Its bioactivity may be due to its incorporation of major compounds, such as chlorogenic acid, quercetin, protocatechuic acid, lamioside, crocetin, and khayasin C. These results suggest that EEAB may be used as a potent antioxidant and hepatoprotective agent since it is a rich source of flavonoids and phenolic compounds.

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