288 CHAPTER 11 The Ocean and Fisheries
don’t integrate the management of both land and water,
nor do they take into account the main cause of coastal
degradation—sheer human numbers.
Perhaps as many as 60 percent of the world’s popula-
tion live within 150 km(93 mi) of a coastline. Demogra-
phers project that three-fourths of all humans will live in
that area by 2025. To prevent the world’s natural coastal
areas from becoming urban sprawl or continuous strips
of tourist resorts during the 21st century, coastal manage-
ment strategies must be developed that take into account
projections of human population growth and distribution.Human Impacts on Coral Reefs
Although coral formations are important ecosystems,
they are being degraded and destroyed. Large reef for-
mations are being damaged in 90 of the 109 countries
where they are found. According to the latest report of
the Global Coral Reef Monitoring Network, coral reefs inindustry. MARPOL regulations specifically address six types
of marine pollution caused by shipping: oil, noxious liq-
uids, harmful packaged substances, sewage, garbage, and
air pollution released by ships. The most recently adopted
MARPOL regulations, which entered into force in early
2013, strive to reduce greenhouse emissions associated with
shipping, and to improve energy efficiency of ships. Unfor-
tunately, MARPOL is not well enforced in the open ocean.
In the past, U.S. coastal cities such as New York dumped
their sewage sludge into the ocean. Disease-causing viruses
and bacteria from human sewage contaminated shellfish
and other seafood and posed an increasing threat to public
health. The Ocean Dumping Ban Act barred ocean dump-
ing of sewage and industrial waste, beginning in 1991.
Huge quantities of trash containing plastics are re-
leased into the ocean, sometimes accidentally, from
coastal communities or cargo ships. Plastics don’t biode-
grade; they photodegrade, which means that exposure to
light breaks them down into smaller and smaller pieces
that exist for an indefinite period. This trash collects in
certain areas of the open ocean defined by atmospheric
pressure systems. For example, in the north Pacific
gyre—halfway between Hawaii and the U.S. mainland—
researchers are monitoring a continuous array of floating
plastics dubbed the “Eastern Pacific garbage patch.” The
size of this area is difficult to assess because its boundar-
ies shift, and the debris it contains is mostly made up of
tiny, floating plastic pieces not visible by satellite image.
Not only are marine mammals and birds susceptible to
being entangled in and strangled by larger pieces of plas-
tic, but the many filter-feeding organisms near the bottom
of the ocean food chain constantly ingest the smaller de-
graded pieces (Figure 11.13). These plastic pieces may
absorb and transport hazardous chemicals such as PCBs.
Scientists have yet to determine whether these substances
are incorporated into marine food webs when organisms
that ingest the plastic are eaten by other organisms.
Coastal Development
Development of resorts, cities, industries, and agricul-
ture along coasts alters or destroys many coastal ecosys-
tems, including mangrove forests, salt marshes, sea grass
beds, and coral reefs. Many coastal areas are overdevel-
oped, highly polluted, and overfished. Although more
than 50 countries have coastal management strategies,
their goals are narrow and usually deal only with the eco-
nomic development of the thin strips of land that directly
border the oceans. Coastal management plans generally
*>ÃÌVÊ«ÕÌÊÊÌ
iÊVi>ÊUÊ}ÕÀiÊ££°£Î© Photoshot Holdings Ltd/AlamyBud Lehnhausen/Science Sourcea. Larger plastic debris in the ocean can injure
or strangle larger marine organisms such as this
penguin.b. Once plastic
in oceans
degrades into tiny
fragments such
as these taken
from a Costa
Rican beach, it
is ingested by
filter-feeding
organisms.