Despite rapid development of marine renewable energy, relatively little is known of the immediate and future impacts on the surrounding ecosystems. Quantifying the behavior and distribution of animals around marine renewable energy devices is crucial for understanding, predicting, and potentially mitigating any threats posed by these installations. The Flow and Benthic Ecology 4D (FLOWBEC) autonomous seabed platform integrated an Imagenex multibeam echosounder and a Simrad EK60 multifrequency echosounder to monitor marine life in a 120 • sector over ranges up to 50 m, seven to eight times per second. Established target detection algorithms fail within MRE sites, due to high levels of backscatter generated by the turbulent physical dynamics, limiting and biasing analysis to only periods of low current speed. This study presents novel algorithms to extract diving seabirds, fish, and fish schools from the intense backscatter caused by turbulent dynamics in flows of 4 m s −1 . Filtering, detection, and tracking using a modified nearest neighbor algorithm provide robust tracking of animal behavior using the multibeam echosounder. Independent multifrequency target detection is demonstrated using the EK60 with optimally calculated thresholds, scale-sensitive filters, morphological exclusion, and frequency-response characteristics. This provides sensitive and reliable detection throughout the entire water column and at all flow speeds. Dive profiles, depth preferences, predator-prey interactions, and fish schooling behavior can be analyzed, in conjunction with the hydrodynamic impacts of marine renewable energy devices. Coregistration of targets between the acoustic instruments increases the information available, providing quantitative measures including frequency response from the EK60, and target morphology and behavioral interactions from the multibeam echosounder. The analyses draw on deployments at Manuscript

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There is no established approach for dealing with the active acoustic detection of biological targets in highly dynamic aquatic environments where intense physical interference means that standard techniques are unsuitable. This is a particular problem in ecologically important environments with emerging industrial significance such as marine energy extraction sites. We developed an automatic processing method which allows effective target detection with high sensitivity throughout variable acoustic conditions. The method is based on scale-dependent adaptive filtering of data and morphological analysis of short-scale backscatter contributions for the exclusion of intense turbulent features and isolation of biological targets. Echosounder platform deployments around marine energy infrastructure in a tidal channel provide test data which demonstrate the effectiveness of the proposed approach. Target validation and assessment is carried out by the analysis of multifrequency characteristics and direct inspection. The results deliver effective, quantitative, and repeatable assessment of ecological interactions and target distributions with clear implications for environmental assessment in high energy sites and promising applications in other contexts.

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Ladakh, a remote region of India lying between the Himalayas and Tibet, is ethnically and geographically distinct from the rest of the country. Because of its isolation, change came later to Ladakh than to other parts of the Himalayas, but recent years have seen the familiar pattern of social change, human population increase, tourism and rural development beginning to affect the environment. The authors, jointly and individually, made a series of visits to the area to investigate the status of the wildlife and to look at conservation measures.