Rako N.,Marine Conservation Institute |
Fortuna C.M.,Marine Conservation Institute |
Fortuna C.M.,European Commission - Joint Research Center Ispra |
Holcer D.,Marine Conservation Institute |
And 8 more authors.
Marine Pollution Bulletin | Year: 2013
The waters of the Cres-LoŠinj archipelago are subject to intense boat traffic related to the high number of leisure boats frequenting this area during the summer tourist season. Boat noise dominates the acoustic environment of the local bottlenose dolphin (Tursiops truncatus) population. This study investigates the spatial and temporal change in the underwater noise levels due to intense boating, and its effect on the distribution of the bottlenose dolphins. In the period 2007-2009 sea ambient noise (SAN) was sampled across ten acoustic stations. During data collection the presence of leisure boats was recorded if they were within 2. km of the sampling station. Bottlenose dolphin spatial distribution was monitored in the same period. Results showed a strong positive correlation between high SAN levels and boat presence, particularly in the tourist season. Dolphin distribution indicated significant seasonal displacements from noisy areas characterized by the intense leisure boating. © 2012 Elsevier Ltd. Source
Spink J.,Alpine Ocean Seismic Survey Inc. |
Read L.,Gardline Environmental Ltd.
Sea Technology | Year: 2011
Gardline Environmental Ltd. has developed a drop-down, freshwater lens (FWL) camera system that can be used in water depths of up to 300 meters to overcome this issue and produce clear images in previously unsurveyable environments. The system has proven particularly valuable to surveys in shallow-water coastal environments, which is where UK offshore farms are currently being constructed. The FWL system incorporates a Kongsberg OE1 4-208 camera, which records real-time video and captures digital still images in resolutions from 640-by-480 to 2,592-by-1,944 pixels. To accommodate the added structure of the FWL housing with its large, potentially reflective lens, Gardline had to overcome a number of lighting issues. These included ensuring the system could illuminate the seabed adequately and evenly without making it overly bright. The FWL camera was used at 188 stations to ensure high- quality results in the difficult water conditions, providing detailed information on the seabed and habitat types across the project area. Source
Johnston A.,British Trust for Ornithology |
Thaxter C.B.,British Trust for Ornithology |
Austin G.E.,British Trust for Ornithology |
Cook A.S.C.P.,British Trust for Ornithology |
And 8 more authors.
Journal of Applied Ecology | Year: 2015
Many emerging methods for ecological monitoring use passive monitoring techniques, which cannot always be used to identify the observed species with certainty. Digital aerial surveys of birds in marine areas are one such example of passive observation and they are increasingly being used to quantify the abundance and distribution of marine birds to inform impact assessments for proposed offshore wind developments. However, the uncertainty in species identification presents a major hurdle to determining the abundance and distribution of individual species. Using a novel analytical approach, we combined data from two surveys in the same area: aerial digital imagery that identified only 23% of individuals to species level and boat survey records that identified 95% of individuals to species level. The data sets were analysed to estimate the effects of environmental covariates on species density and to produce species-specific estimates of population size. For each digital aerial observation without certain species identification, randomized species assignments were generated using the observed species proportions from the boat surveys. For each species, we modelled several random realizations of species assignments and produced a density surface from the ensemble of models. The uncertainty from each stage of the process was propagated, so that final confidence limits accounted for all sources of uncertainty, including species identification. In the breeding season, several species had higher densities near colonies and this pattern was clearest for three auk species. Sandeel density was an important predictor of the density of several gull species. Synthesis and applications. This method shows it is possible to construct maps of species density in situations in which ecological observations cannot be identified to species level with certainty. The increasing use of passive detection methods is providing many more data sets with uncertain species identification and this method could be used with these data to produce species-specific abundance estimates. We discuss the advantages of this approach for estimating the abundance and distribution of birds in marine areas, particularly for quantifying the impacts of offshore renewable developments by making the estimates derived from the older digital surveys more comparable to the recently improved surveys. This method shows it is possible to construct maps of species density in situations in which ecological observations cannot be identified to species level with certainty. The increasing use of passive detection methods is providing many more data sets with uncertain species identification and this method could be used with these data to produce species-specific abundance estimates. We discuss the advantages of this approach for estimating the abundance and distribution of birds in marine areas, particularly for quantifying the impacts of offshore renewable developments by making the estimates derived from the older digital surveys more comparable to the recently improved surveys. © 2014 British Ecological Society. Source
Barber R.,Gardline Environmental Ltd. |
Sikora I.,Gardline Environmental Ltd. |
Nimak-Wood M.,Gardline Environmental Ltd.
African Journal of Marine Science | Year: 2016
Observations of blue whales were made in Kenyan offshore waters during a seismic survey from September 2014 to January 2015. These represent the first live at-sea sightings of blue whales reported from Kenyan waters. All 30 sightings occurred between September and October in waters ranging from 2 990 to 4 705 m depth. It is unknown to which of the three possible subspecies the animals sighted belong. Based on timing and geographical location, they are likely to have been either Antarctic blue whales Balaenoptera musculus intermedia, Madagascar pygmy blue whales B. m. brevicauda or northern Indian Ocean blue whales B. m. indica. © 2016 NISC (Pty) Ltd Source