in Context the SCotian Shelf - COINAtlantic

whales, the sperm whale and the Northern bottlenose
whale, was carried out for the Scotian Shelf in
light of ongoing petroleum exploration activities in the
area (LGL Llimited and Malme 2000).
4.5 Pollution
Shipping, petroleum exploration and development,
disposal at sea (e.g., of dredging material) and fishing
activities all discharge wastes into the marine
environment. However, the largest source of marine
pollution comes from land-based activities, including
agricultural runoff, wind-blown debris, industrial
activity, and municipal waste-water (Environment
Canada 2004). Stewart and White (2001) provide
a general overview of contaminants on the Scotian
Shelf. Some marine sources of pollution on the
Scotian Shelf are briefly described here.
The offshore oil and gas industry discharges treated
water into the marine environment. Oil and
gas operators are expected to meet guidelines
published by the CNSOPB (CNSOPB/C-NLOPB
2010). Discharges from the shipping industry
are regulated; however, there are incidental and
accidental releases of fuel, chemicals, ship debris
and cargoes (Stewart and White 2001) as well as
occasional major events, such as the sinking of
the oil tanker, Arrow, in Chedabucto Bay in 1970
(Environment Canada 2010). The major sources
of pollution from the fishing industry are lost or
abandoned fishing gear and garbage. Two studies
carried out in the 1990s found that fishing
was the most important source of marine litter in
offshore areas of the Scotian Shelf (Lucas 1992;
Dufault and Whitehead 1994). Since then, fishermen’s
organizations have been active in developing
programs to encourage fishermen to bring
garbage back to shore. The federal government
has also developed awareness brochures and
other awareness tools (DFO 2007b).
4.6 Cumulative Effects
A cumulative effect may be defined as “a change
to the environment caused by an action in
combination with other past, present and future
human actions” (Hegmann et al. 1999). Cumulative
effects are important when the effects of an
ocean use are persistent over time (i.e., difficult
to reverse), such as pollution with heavy metals
and some pesticides or large-scale destruction of
habitat, or when activities are in close proximity in
time and space. When environmental effects of
activities are considered separately, they may all
be below the threshold levels that cause impacts.
Some effects, although thought to be transitory
or of minor importance on the scale of a single
source (e.g., a vessel discharge, an otter trawler,
an oil well, or a seismic survey) may prove to be
of more serious concern when combined. Cumulative
effects need to be addressed at varying
scales, from local/site-specific to broader regional
ecosystems.
4.7 Multiple Use
Some portions of the Scotian Shelf experience
relatively high or intensive levels of use, such
as heavily fished areas, hydrocarbon production
areas, and high vessel traffic areas. Parts of the
outer shelf and shelf break, for example, has been
subject to an increasing intensity of multiple use,
including oil and gas development and a variety of
fisheries. Other areas remain little to moderately
used. Current and anticipated expansion, however,
of existing uses (e.g., deep water fisheries) coupled
with the potential for new ocean uses, such
as offshore minerals development or wind power
generation, underscores the growing requirement
for effective multiple use management practices.
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