Dear MARMAMers,
We are pleased to announce publication (including supplementary on-line
data) of the following article:
Victoria L. G. Todd, Ian B. Todd, Jane C. Gardiner, Erica C. N. Morrin,
Nicola A. MacPherson, Nancy A. DiMarzio, and Frank Thomsen 2014: A
review of impacts of marine dredging activities on marine mammals. /ICES
Journal of Marine Science/, doi: 10.1093/icesjms/fsu187.
*Abstract*
Marine dredging is an excavation activity carried out worldwide by many
industries. Concern about the impact dredging has on marine life,
including marine mammals (cetaceans, pinnipeds, and sirenians) exists,
but effects are largely unknown. Through consulting available
literature, this review aims to expand on existing knowledge of the
direct and indirect, negative and positive impacts on marine mammals. In
terms of direct effects, collisions are possible, but unlikely, given
the slow speed of dredgers. Noise emitted is broadband, with most energy
below 1 kHz and unlikely to cause damage to marine mammal auditory
systems, but masking and behavioural changes are possible. Sediment
plumes are generally localized, and marine mammals reside often in
turbid waters, so significant impacts from turbidity are improbable.
Entrainment, habitat degradation, noise, contaminant remobilization,
suspended sediments, and sedimentation can affect benthic, epibenthic,
and infaunal communities, which may impact marine mammals indirectly
through changes to prey. Eggs and larvae are at highest risk from
entrainment, so dredging in spawning areas can be detrimental, but
effects are minimized through the use of environmental windows.
Sensitive environments such as seagrass beds are at risk from
smothering, removal, or damage, but careful planning can reduce
degradation. Assessing impacts of contaminant remobilization is
difficult, but as long as contaminated sediments are disposed of
correctly, remobilization is limited in space and time. Effects of
suspended sediments and sedimentation are species-specific, but
invertebrates, eggs, and larvae are most vulnerable. Positive effects,
including an increase in food, result from greater nutrient loads, but
are often short term. Dredging has the potential to impact marine
mammals, but effects are species and location-specific, varying also
with dredging equipment type. In general, evidence suggests that if
management procedures are implemented, effects are most likely to be
masking and short-term behavioural alterations and changes to prey
availability.
*Supplementary data*
The supplementary data feature a world map of regional boundaries used
to compose distributions of marine mammals, and a referenced world-wide
review table, that lists family, scientific names, common name, range of
best hearing (10 dB from max; kHz), frequency of minimum hearing
threshold (kHz), minimum hearing threshold (dB re 1 µPa), methodology,
diet, region, habitat, documented effects of dredging, and potential
effects of dredging. The table was created to assist stakeholders in
developing mitigation plans for dredging activities that have potential
to impact marine mammals.
If you subscribe to /ICES J. Mar. Sci./ the article and supplementary
are available at
http://icesjms.oxfordjournals.org/content/early/2014/11/04/icesjms.fsu187.abstract,
or you can download the PDF and supplementary material on
http://www.osc.co.uk/publications-and-press-covers/
Brgds,
--
Dr. Victoria Todd
Managing Director
OSC Ltd.
Ocean House, 4 Brewery Lane
Belhaven, Dunbar, East Lothian
Scotland, EH42 1PD
T: +44 (0)1368 865 722
M: +44 (0)7719 489 415
F: +44 (0)1368 865 729
W: www.osc.co.uk
E: [email protected]
*MMO or PAM requirement?*
We wrote the book. Now available on Amazon:
/www.marinemammalobserverhandbook.com/
View Victoria Todd's profile on LinkedIn
<http://uk.linkedin.com/in/victoriatodd1>**
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