Confusion Reigns? A Review of Marine Megafauna Interactions with Tidal-Stream Environments

Benjamins, Steven; Dale, Andrew; Hastie, Gordon D.; Waggitt, James J.; Lea, Mary-Anne; Scott, Beth E.; Wilson, Ben

doi:10.1201/b18733-2

Cited by 63 publications

(122 citation statements)

References 245 publications

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“…Associations between foraging seabirds and predictable physical conditions typically concern prey characteristics, with particular hydrodynamic (Benjamins et al, 2015;Hunt et al, 1999) or seabed features (Watanuki et al, 2008) being characterized by dense and exploitable aggregations of prey items. It also seems possible that the longer and deeper dives associated with the exploitation of prey on the seabed (Elliott et al, 2009) could result with benthic foraging species showing additional associations with physical conditions suspected to influence the performance of dives (Butler and Jones, 1997;Heath and Gilchrist, 2010).…”

Section: Hydrodynamic Conditionsmentioning

confidence: 99%

“…Intensive studies focussing upon areas of high horizontal current speeds are essential for this understanding, as foraging behaviours observed within these areas are likely to be very different to those within more benign areas. These differences in behaviour are likely to be driven by the unique physical characteristics of the former (Benjamins et al, 2015). However, few studies have investigated a species foraging behaviours within very specific areas (< 1 km 2 ) (Heithaus, 2005;Watanuki et al, 2008), and none have focussed on areas of high horizontal current speeds.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, seabirds may exploit times of faster horizontal currents to cover larger seabed areas or track epi-benthic fish as they are washed downstream (Holm and Burger, 2002;Robbins et al, 2014). Seabirds could also exploit times of high turbulence, originating from interactions between fast horizontal currents and bathymetry, when three-dimensionally complex motions could flush benthic and epi-benthic prey into open water and/or restrict their anti-predatory responses (Benjamins et al, 2015;Hunt et al, 1999). However, on the other hand, seabirds could avoid times of particularly high horizontal current speeds, extreme turbulence or deeper water elevation (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Predictable hydrodynamic conditions explain temporal variations in the density of benthic foraging seabirds in a tidal stream environment

et al. 2016

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Tidal stream turbines could have several direct impacts upon pursuit-diving seabirds foraging within tidal stream environments (mean horizontal current speeds > 2 ms À1 ), including collisions and displacement. Understanding how foraging seabirds respond to temporally variable but predictable hydrodynamic conditions immediately around devices could identify when interactions between seabirds and devices are most likely to occur; information which would quantify the magnitude of potential impacts, and also facilitate the development of suitable mitigation measures. This study uses shore-based observational surveys and Finite Volume Community Ocean Model outputs to test whether temporally predictable hydrodynamic conditions (horizontal current speeds, water elevation, turbulence) influenced the density of foraging black guillemots Cepphus grylle and European shags Phalacrocorax aristotelis in a tidal stream environment in Orkney, United Kingdom, during the breeding season. These species are particularly vulnerable to interactions with devices due to their tendency to exploit benthic and epi-benthic prey on or near the seabed. The density of both species decreased as a function of horizontal current speeds, whereas the density of black guillemots also decreased as a function of water elevation. These relationships could be linked to higher energetic costs of dives in particularly fast horizontal current speeds (>3 ms À1 ) and deeper water. Therefore, interactions between these species and moving components seem unlikely at particularly high horizontal current speeds. Combining this information, with that on the rotation rates of moving components at lower horizontal current speeds, could be used to assess collision risk in this site during breeding seasons. It is also likely that moderating any device operation during both lowest water elevation and lowest horizontal current speeds could reduce the risk of collisions for these species in this site during this season. The approaches used in this study could have useful applications within Environmental Impact Assessments, and should be considered when assessing and mitigating negative impacts from specific devices within development sites.

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Section: Hydrodynamic Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Predictable hydrodynamic conditions explain temporal variations in the density of benthic foraging seabirds in a tidal stream environment

et al. 2016

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“…Many tidal rapid areas are thought to be important areas for foraging (Pierpoint, 2008;Benjamins et al, 2015). During foraging harbour porpoises click rates increase and in the final phase of prey capture reach $600 clicks per second [an inter click interval (ICI) of 1.67 ms] (Verfuß et al, 2009) (2) Two or more individuals vocalising at the same time.…”

Section: Click Match Uncertaintymentioning

confidence: 99%

“…As the industry expands, the large scale deployment of tidal turbines and resulting inevitable increase in anthropogenic activity could also displace such animals (Frid et al, 2012). Little information exists on the interactions between tidal rapid areas and marine megafauna and thus the potential consequences of such habitat exclusion are not known (indeed a recent comprehensive review is titled "Confusion Reigns"; Benjamins et al, 2015). Of the multiple information gaps which exist in this area, the fine scale underwater movements and depth distributions of marine megafauna is perhaps least understood, yet forms a key parameter in assessing both collision risk (Thompson and Lonergan, 2015) and habitat usage.…”

mentioning

confidence: 99%

Passive acoustic methods for fine-scale tracking of harbour porpoises in tidal rapids

Macaulay

Gordon

Gillespie

et al. 2017

The Journal of the Acoustical Society of America

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The growing interest in generating electrical power from tidal currents using tidal turbine generators raises a number of environmental concerns, including the risk that marine mammals might be injured or killed through collision with rotating turbine blades. To understand this risk, information on how marine mammals use tidal rapid habitats and in particular, their underwater movements and dive behaviour is required. Porpoises, which are the most abundant small cetacean at most European tidal sites, are difficult animals to tag, and the limited size of tidal habitats means that any telemetered animal would be likely to spend only a small proportion of time within them. Here, an alternative approach is explored, whereby passive acoustic monitoring (PAM) is used to obtain fine scale geo-referenced tracks of harbour porpoises in tidal rapid areas. Large aperture hydrophone arrays are required to obtain accurate locations of animals from PAM data and automated algorithms are necessary to process the large quantities of acoustic data collected on such systems during a typical survey. Methods to automate localisation, including a method to match porpoise detections on different hydrophones and separate different vocalising animals, and an assessment of the localisation accuracy of the large aperture hydrophone array are presented.

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Confusion Reigns? A Review of Marine Megafauna Interactions with Tidal-Stream Environments

Cited by 63 publications

References 245 publications

Predictable hydrodynamic conditions explain temporal variations in the density of benthic foraging seabirds in a tidal stream environment

Predictable hydrodynamic conditions explain temporal variations in the density of benthic foraging seabirds in a tidal stream environment

Passive acoustic methods for fine-scale tracking of harbour porpoises in tidal rapids

Might marine protected areas for mobile megafauna suit their proponents more than the animals?

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