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Reviews the literature generated by R. M. Liebert and L. W. Morris's (1967) 2-component conceptualization of anxiety, specifically test anxiety, and other related theoretical and research programs. It is concluded (a) that the inverse relationship between anxiety and various performance variables under appropriate conditions is attributable primarily to the worry–performance relationship, supporting a cognitive–attentional view of performance deficits; (b) that the 2 components are probably aroused and maintained by different aspects of stressful situations; certainly worry may or may not be accompanied by the emotional component; and (c) that efforts to apply the distinction to the development of more effective treatment techniques have been productive. Recent advances in assessment are noted, and a revised worry–emotionality questionnaire is presented, along with the factor-analytic evidence on which it is based. A social learning position is used to provide further theoretical perspective. (2½ p ref)

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Aim Environmental DNA (eDNA) is a rapidly emerging methodology with important applications to environmental management and conservation. However, the effects of stream flow or discharge on eDNA have been minimally investigated in lotic (stream and river) environments. In this study, we examined the role of stream flow on eDNA concentrations and detectability of an invasive clam (Corbicula fluminea), while also accounting for other abiotic and biotic variables. Location Illinois, United States of America. Methods We used a longitudinal study over a year in two streams, as well as a seasonal study (summer, autumn) in eight streams, to investigate the effects of variable stream flow on eDNA concentrations and detectability. We used linear mixed‐effects models to assess the influence of various factors on eDNA concentration and occupancy models to make predictions on how seasonality can influence eDNA detection. Results We found higher stream flows decreased eDNA concentrations, and floods produced false negatives or non‐detections at locations where C. fluminea was relatively common. In addition, we found concentrations and detectability of C. fluminea eDNA to be higher in summer than in autumn. Main conclusions We found that stream flow dilutes eDNA concentrations, which may have serious implications for the detection of low abundance organisms. Managers and practitioners applying eDNA for rare species should seek to sample at low or base stream flows when feasible, and future studies should investigate whether our findings here are consistent for other taxa and lotic ecosystems.

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