Living Blue Planet Report page 38
Until the 1970s, dumping rubbish in the ocean had been an
accepted practice for centuries. Marine debris can travel immense
distances: it creates navigation hazards, smothers coral reefs,
transports invasive species and negatively affects tourism. It also
injures and kills wildlife; at least 17 per cent of species affected
by entanglement and ingestion of marine debris are listed as
threatened or near threatened on the IUCN Red List. It also may
pose a threat to human health (Gall and Thompson, 2014).
Plastic debris is of particular concern due to its abundance
and its persistence in the environment. There are estimated to be
over 5 trillion plastic pieces weighing over 250,000 tonnes afloat at
sea (Eriksen et al., 2014). We are only just beginning to understand
the level and impact of microplastics – tiny plastic particles of which
around 35,500 tonnes are estimated to be floating in our ocean
(Eriksen et al., 2014). Many more organisms ingest small plastic
particles than previously thought, and these work their way up the
food chain (Cole, 2013; Lusher et al., 2013).
Meanwhile, fertilizer run-off from farms and residential
lawns causes eutrophication – the flourishing of algal blooms that
deplete the water’s dissolved oxygen and suffocate marine life
(Rabalais, 2002; Selman et al., 2008). Eutrophication has created
enormous “dead zones” in several parts of the world, including the
Gulf of Mexico and Baltic Sea, reducing species diversity (Smith
and Schindler, 2009) and sometimes leading to toxic algal blooms
known as red tides (Anderson et al., 2008; Rabalais, 2002). Dead
zones are growing in both magnitude and geographical extent
(Selman et al., 2008).
Toxic wastes from industries continue to be discharged into
our major water bodies, through deliberate illegal dumping or
through run-off from land-based activities. Almost every marine
organism, from the tiniest plankton to whales and polar bears, is
contaminated with man-made chemicals, such as pesticides and
chemicals used in common consumer products (Garcia-Hernandez
et al., 2007; Dorneles et al., 2013; Seltenrich, 2015).
With at least 60 per cent of the world’s population living
within 100km of the coast and the global population growing,
marine pollution from land-based activities is likely to worsen.
Given the transboundary nature of marine pollution, protection
of our ocean from land-based activities requires urgent
international cooperation.
Land-based
sources are
responsible for
80% of marine
pollution