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

2015 ◽  
pp. 10-63 ◽  
Keyword(s):  
Tidal Stream ◽  
Marine Megafauna

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

2015 ◽  
pp. 1-54 ◽  
Author(s):  
Steven Benjamins ◽  
Andrew Dale ◽  
Gordon Hastie ◽  
James Waggitt ◽  
Mary-Anne Lea ◽  
...  
Keyword(s):  
Tidal Stream ◽  
Marine Megafauna

Seal movements in tidal stream environments: Novel methods and ecological insights for the tidal stream turbine industry

2021 ◽  
Author(s):  
◽  
William P. Kay
Keyword(s):  
Management Strategies ◽  
Conservation Strategies ◽  
Marine Renewable Energy ◽  
The North ◽  
Harbour Seals ◽  
The North Sea ◽  
Tidal Stream ◽  
Marine Megafauna ◽  
The Uk ◽  
Tidal Stream Turbine

With the increasing threats of climate change, there is an ever-pressing need to reduce fossil fuel emissions. Thus, recent years have seen a dramatic increase in the development of marine renewable energy (MRE) devices – in particular tidal stream turbines (TSTs) – to exploit tidal stream environments (TSEs) for green electricity generation. However, TSTs may pose threats to marine megafauna and relatively little is known about how animals operate in the environments targeted by these devices, and how they may be affected by them. This information is crucial for informing appropriate management strategies to mitigate the risk of conflict between animals and TST developments. Here, using grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) as my study species, with data collected from around the UK and neighbouring waters, including the Celtic and the North Sea, I aim to understand and quantify how seals move in TSEs and the implications of this for the TST industry. To achieve this, I quantify the broad-scale movement patterns of seals in coastal waters and their overlap with TSTs, examine the fine-scale movement and behaviour of seals in response to tidal conditions, derive recommendations on sample size and recording duration for animal tracking studies, and design new tags to track seals in TSEs at very fine-scales whilst minimising tag impact. My results suggest that the movements and behaviour of seals are driven by a combination of measurable (and in some cases predictable) demographic and environmental factors, and that the conservation strategies developed to manage the interaction between individuals and populations with TST devices must consider site-specific differences and account for individual variation, with consequences regarding data requirements. Further investigation is required to fully elucidate the extent of variability of seal movements in TSEs and the threats of TST developments, however the research presented herein provides new tools and ecological insights to support this need for both researchers and practitioners.

One-power-point operation for variable speed wind/tidal stream turbines with synchronous generators

2011 ◽  
Vol 5 (1) ◽  
pp. 99 ◽  
Author(s):  
H.-B. Zhang ◽  
J. Fletcher ◽  
N. Greeves ◽  
S.J. Finney ◽  
B.W. Williams
Keyword(s):  
Variable Speed ◽  
Synchronous Generators ◽  
Tidal Stream ◽  
Power Point

scholarly journals North Pacific warming shifts the juvenile range of a marine apex predator

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kisei R. Tanaka ◽  
Kyle S. Van Houtan ◽  
Eric Mailander ◽  
Beatriz S. Dias ◽  
Carol Galginaitis ◽  
...  
Keyword(s):  
North Pacific ◽  
Species Conservation ◽  
Total Body Length ◽  
Suitable Habitat ◽  
Climate Data ◽  
Marine Predator ◽  
Spatial Shift ◽  
Marine Megafauna ◽  
Community Science ◽  
Juvenile Sharks

AbstractDuring the 2014–2016 North Pacific marine heatwave, unprecedented sightings of juvenile white sharks (Carcharodon carcharias) emerged in central California. These records contradicted the species established life history, where juveniles remain in warmer waters in the southern California Current. This spatial shift is significant as it creates potential conflicts with commercial fisheries, protected species conservation, and public safety concerns. Here, we integrate community science, photogrammetry, biologging, and mesoscale climate data to describe and explain this phenomenon. We find a dramatic increase in white sharks from 2014 to 2019 in Monterey Bay that was overwhelmingly comprised of juvenile sharks < 2.5 m in total body length. Next, we derived thermal preferences from 22 million tag measurements of 14 juvenile sharks and use this to map the cold limit of their range. Consistent with historical records, the position of this cold edge averaged 34° N from 1982 to 2013 but jumped to 38.5° during the 2014–2016 marine heat wave. In addition to a poleward shift, thermally suitable habitat for juvenile sharks declined 223.2 km2 year−1 from 1982 to 2019 and was lowest in 2015 at the peak of the heatwave. In addition to advancing the adaptive management of this apex marine predator, we discuss this opportunity to engage public on climate change through marine megafauna.

scholarly journals ASKAP observations of multiple rapid scintillators reveal a degrees-long plasma filament

2021 ◽  
Vol 502 (3) ◽  
pp. 3294-3311
Author(s):  
Yuanming Wang ◽  
Artem Tuntsov ◽  
Tara Murphy ◽  
Emil Lenc ◽  
Mark Walker ◽  
...  
Keyword(s):  
Physical Properties ◽  
Angular Width ◽  
Scattering Medium ◽  
Central Frequency ◽  
Linear Arrangement ◽  
Plasma Filament ◽  
Kinematic Models ◽  
Tidal Stream ◽  
First Time ◽  
Insight Into

ABSTRACT We present the results from an Australian Square Kilometre Array Pathfinder search for radio variables on timescales of hours. We conducted an untargeted search over a 30 deg2 field, with multiple 10-h observations separated by days to months, at a central frequency of 945 MHz. We discovered six rapid scintillators from 15-min model-subtracted images with sensitivity of $\sim\! 200\, \mu$Jy/beam; two of them are extreme intra-hour variables with modulation indices up to $\sim 40{{\ \rm per\ cent}}$ and timescales as short as tens of minutes. Five of the variables are in a linear arrangement on the sky with angular width ∼1 arcmin and length ∼2 degrees, revealing the existence of a huge plasma filament in front of them. We derived kinematic models of this plasma from the annual modulation of the scintillation rate of our sources, and we estimated its likely physical properties: a distance of ∼4 pc and length of ∼0.1 pc. The characteristics we observe for the scattering screen are incompatible with published suggestions for the origin of intra-hour variability leading us to propose a new picture in which the underlying phenomenon is a cold tidal stream. This is the first time that multiple scintillators have been detected behind the same plasma screen, giving direct insight into the geometry of the scattering medium responsible for enhanced scintillation.

The impact of the seabed morphology on turbulence generation in a strong tidal stream

2021 ◽  
Vol 33 (5) ◽  
pp. 055125
Author(s):  
Philippe Mercier ◽  
Sylvain Guillou
Keyword(s):  
Tidal Stream ◽  
Turbulence Generation ◽  
The Impact
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