37
species to another (valence states, metal speciation) and can switch metals back and
forth from inorganic to organic forms. Although metals such as copper (Cu) and
zinc (Zn) are essential to life, others such as lead (Pb), cadmium (Cd), and mercury
(Hg) do not have known useful biochemical functions (Allan 1997). Additionally,
excess intake of any of these metals can be highly toxic when exceeding certain
concentration thresholds. It is important to mention that although Cd is not essential, and is potentially toxic even in very low doses, it enhances phytoplankton photosynthesis and growth rate by increasing carbonic anhydrase activity in cells
(Cullen et al. 1999).
Seaweeds are fundamental components of coastal benthic ecosystems and are
responsible for much of the coastal primary production, community structure, and
ecosystem function (Hurd et al. 2014; Schiel and Foster 2015). Natural or anthropogenic phenomena, such as heavy metal deposition, can adversely affect macroalgae,
which in turn can directly or indirectly affect organisms at higher trophic levels and,
ultimately, the integrity of entire ecosystems. For example, the deposition of copper
into Chañaral Bay (26°S, 71°W) in northern Chile through the transport of mining
wastes to the coast, occurring since 1938, negatively influenced algal biodiversity
and eliminated several benthic herbivores and all benthic carnivores (Correa et al.
2000; Medina et al. 2005). This waste deposition has resulted in persistently high
levels of total copper in the seawater, with 20 μg L
−1
currently and 200 μg L
−1
at the
discharge point in the past (Castilla 1996; Henríquez-Castillo et al. 2015).
Particularly, the brown kelp Lessonia berteroana (Phaeophyceae) (formerly L.
nigrescens), a keystone species dominating the lower intertidal rocky shores along the
northern Chilean coast, is absent from this copper-enriched area (Medina et al. 2005;
Lovazzano et al. 2013). Since Lessonia spp. regulate community structure (Cancino
and Santelices 1984), the absence of L. berteroana has negatively impacted local
biodiversity. It is important to emphasize that the high heavy metal concentration in
seawater is not restricted to northern Chile. According to POAL (Coastal Monitoring
Program, Chilean Navy DIRECTEMAR: www.directemar.cl), over the last 5 years,
certain central coastal zones of Chile have registered close to 14 μg L
−1
of total dissolved Cu, 5.5 μg L
−1
of Cd, and 7 μg L
−1
of Pb in the seawater, levels considered
toxic for certain marine organisms by the Environmental Protection Agency (EPA) of
the United States and as low-quality seawater by Chilean standards.
The excess presence of heavy metals can inhibit photosynthesis (Nielsen et al.
2003; Xia et al. 2004), reduce pigment concentration and growth (Contreras et al.
2007), and induce a loss of cations (Overnell 1975; Brown and Newman 2003).
Particularly, copper and cadmium can disrupt gametophyte development in the
brown kelp Macrocystis pyrifera (Phaeophyceae) and Lessonia spicata (Anderson
and Hunt 1988; Garman et al. 1994; Contreras et al. 2007). These heavy metals also
affect the distribution of other cellular compounds, such as free fatty acids (Ritter
et al. 2008), as well as competitively inhibiting other metals (Franklin et al. 2002;
Andrade et al. 2006). Therefore, it is clear that attenuation responses in seaweeds
are necessary for controlling the adverse and environmentally stressful conditions
that result from heavy metal over-enrichment.
3 Marine Metal Pollution and Effects on Seaweed Species
species to another (valence states, metal speciation) and can switch metals back and
forth from inorganic to organic forms. Although metals such as copper (Cu) and
zinc (Zn) are essential to life, others such as lead (Pb), cadmium (Cd), and mercury
(Hg) do not have known useful biochemical functions (Allan 1997). Additionally,
excess intake of any of these metals can be highly toxic when exceeding certain
concentration thresholds. It is important to mention that although Cd is not essential, and is potentially toxic even in very low doses, it enhances phytoplankton photosynthesis and growth rate by increasing carbonic anhydrase activity in cells
(Cullen et al. 1999).
Seaweeds are fundamental components of coastal benthic ecosystems and are
responsible for much of the coastal primary production, community structure, and
ecosystem function (Hurd et al. 2014; Schiel and Foster 2015). Natural or anthropogenic phenomena, such as heavy metal deposition, can adversely affect macroalgae,
which in turn can directly or indirectly affect organisms at higher trophic levels and,
ultimately, the integrity of entire ecosystems. For example, the deposition of copper
into Chañaral Bay (26°S, 71°W) in northern Chile through the transport of mining
wastes to the coast, occurring since 1938, negatively influenced algal biodiversity
and eliminated several benthic herbivores and all benthic carnivores (Correa et al.
2000; Medina et al. 2005). This waste deposition has resulted in persistently high
levels of total copper in the seawater, with 20 μg L
−1
currently and 200 μg L
−1
at the
discharge point in the past (Castilla 1996; Henríquez-Castillo et al. 2015).
Particularly, the brown kelp Lessonia berteroana (Phaeophyceae) (formerly L.
nigrescens), a keystone species dominating the lower intertidal rocky shores along the
northern Chilean coast, is absent from this copper-enriched area (Medina et al. 2005;
Lovazzano et al. 2013). Since Lessonia spp. regulate community structure (Cancino
and Santelices 1984), the absence of L. berteroana has negatively impacted local
biodiversity. It is important to emphasize that the high heavy metal concentration in
seawater is not restricted to northern Chile. According to POAL (Coastal Monitoring
Program, Chilean Navy DIRECTEMAR: www.directemar.cl), over the last 5 years,
certain central coastal zones of Chile have registered close to 14 μg L
−1
of total dissolved Cu, 5.5 μg L
−1
of Cd, and 7 μg L
−1
of Pb in the seawater, levels considered
toxic for certain marine organisms by the Environmental Protection Agency (EPA) of
the United States and as low-quality seawater by Chilean standards.
The excess presence of heavy metals can inhibit photosynthesis (Nielsen et al.
2003; Xia et al. 2004), reduce pigment concentration and growth (Contreras et al.
2007), and induce a loss of cations (Overnell 1975; Brown and Newman 2003).
Particularly, copper and cadmium can disrupt gametophyte development in the
brown kelp Macrocystis pyrifera (Phaeophyceae) and Lessonia spicata (Anderson
and Hunt 1988; Garman et al. 1994; Contreras et al. 2007). These heavy metals also
affect the distribution of other cellular compounds, such as free fatty acids (Ritter
et al. 2008), as well as competitively inhibiting other metals (Franklin et al. 2002;
Andrade et al. 2006). Therefore, it is clear that attenuation responses in seaweeds
are necessary for controlling the adverse and environmentally stressful conditions
that result from heavy metal over-enrichment.
3 Marine Metal Pollution and Effects on Seaweed Species