36
4 Management and Conservation of Marine Life
Other conservation issue to be taken into account regarding fronts is their
potential to concentrate several types of pollutants at their convergent surface
(Fig. 4.2), thus endangering species that use these areas (Belkin et al. 2009;
Lohmann and Belkin 2014). One of the most ubiquitous and long-lasting changes
to oceans is the accumulation and fragmentation of plastics. Many plastics are
buoyant and remain so until they become waterlogged or accumulates too much
epibiota to float. Mega- and macro-plastics have accumulated in the highest densities in the Northern Hemisphere, adjacent to urban centers, in enclosed seas and
at fronts (Barnes et al. 2009). In the North Pacific, a large increase in debris density occurs at the Subtropical Convergence Zone, north of the Hawaiian Islands;
increasing risk for pelagic animals that are preferentially foraging in the same
frontal zone (Pichel et al. 2007). In the German Bight, the distribution of floating objects is driven by winds and surface currents. During calm weather, when
relatively stable fronts form in the bight, floating objects accumulate near these
interfaces (Thiel et al. 2011). The Agulhas Current appears to be a major source
of plastic pollution to the seas off the southwestern Cape Province, South Africa,
where frontal convergences produce the highest concentrations (Ryan 1988).
Fronts can also accumulate non-plastic pollutants (Lohmann and Belkin 2014).
Near the Galician coasts (northwest of Spain), a marked surface front is formed
by the meeting of a poleward current and lower salinity coastal waters. This front
Fig. 4.2 Fronts are able to
concentrate floating debris. a
Garbage patches in the Gulf
of Maine (Rozalia Project for
a Clean Ocean http://rozali
aproject.blogspot.com.ar/).
b Debris float in the Pacific
Ocean off the coast of Japan
after the Tsunami that struck
the nation on March 11, 2011
(U.S. Navy photo by Steve
White)
4 Management and Conservation of Marine Life
Other conservation issue to be taken into account regarding fronts is their
potential to concentrate several types of pollutants at their convergent surface
(Fig. 4.2), thus endangering species that use these areas (Belkin et al. 2009;
Lohmann and Belkin 2014). One of the most ubiquitous and long-lasting changes
to oceans is the accumulation and fragmentation of plastics. Many plastics are
buoyant and remain so until they become waterlogged or accumulates too much
epibiota to float. Mega- and macro-plastics have accumulated in the highest densities in the Northern Hemisphere, adjacent to urban centers, in enclosed seas and
at fronts (Barnes et al. 2009). In the North Pacific, a large increase in debris density occurs at the Subtropical Convergence Zone, north of the Hawaiian Islands;
increasing risk for pelagic animals that are preferentially foraging in the same
frontal zone (Pichel et al. 2007). In the German Bight, the distribution of floating objects is driven by winds and surface currents. During calm weather, when
relatively stable fronts form in the bight, floating objects accumulate near these
interfaces (Thiel et al. 2011). The Agulhas Current appears to be a major source
of plastic pollution to the seas off the southwestern Cape Province, South Africa,
where frontal convergences produce the highest concentrations (Ryan 1988).
Fronts can also accumulate non-plastic pollutants (Lohmann and Belkin 2014).
Near the Galician coasts (northwest of Spain), a marked surface front is formed
by the meeting of a poleward current and lower salinity coastal waters. This front
Fig. 4.2 Fronts are able to
concentrate floating debris. a
Garbage patches in the Gulf
of Maine (Rozalia Project for
a Clean Ocean http://rozali
aproject.blogspot.com.ar/).
b Debris float in the Pacific
Ocean off the coast of Japan
after the Tsunami that struck
the nation on March 11, 2011
(U.S. Navy photo by Steve
White)