36
constituents such as DNA/RNA, proteins, and lipids. To cope with heavy metal
excess, several mechanisms exist in tolerant seaweed species, including the activation of an efficient ROS-scavenging system constituted by metal-binding compounds, antioxidant enzymes, and oxygenated polyunsaturated fatty acids, among
others. Another adaptive mechanism involves the participation of ATP-binding
cassette (ABC) transporter proteins in translocating a wide variety of compounds
across cell membranes, including heavy metals. In contrast, an excessive heavy
metal presence can inhibit photosynthesis, reduce pigment concentration and growth,
induce cation losses, and disrupt gametophyte development in non-tolerant seaweed
species. In a scenario of lowered ocean pH and increased heavy metal toxicity, the
important roles played by non-tolerant seaweed species in structuring communities
could be severely compromised, with unknown consequences for associated organisms. Therefore, in the upcoming decades, marine pollution could majorly shift and
rearrange community compositions and the distributional ranges of species.
Keywords Seaweeds • Heavy metal stress • Tolerance mechanisms • Ocean
acidification
Contents
3.1 Heavy Metal Toxicity in Marine Ecosystems
36
3.2 Tolerance Mechanisms in Seaweeds to Heavy Metal Toxicity
38
3.3 Influence of Abiotic Factors on Metal Toxicity: The Case of the Ocean
Acidification
40
3.4 Seaweeds as a Study Model for Heavy Metal Toxicity and Ocean Acidification
42
3.5 Conclusion
44
References
44
3.1 Heavy Metal Toxicity in Marine Ecosystems
Heavy metals are significant toxic pollutants, and extensive literature details the accumulation of heavy metals in coastal marine ecosystems (Walker et al. 2012). Metals
are continuously released into the biosphere by volcanoes and the natural weathering
of rocks, in addition to release through numerous anthropogenic activities such as
mining, fuel combustion, and industrial, urban, and agricultural activities.
The input of metals into the sea, natural or anthropogenic in origin, is mainly via
the atmosphere, whereas the anthropogenic contribution of some metals (e.g., copper, cadmium, and lead) is greater than from natural sources (Duce et al. 1991).
Metal deposition occurs primarily through a gas exchange at the sea surface, through
either particle fallout (dry deposition) or through dragging from the air by rain (wet
deposition) (Walker et al. 2012).
Unlike organic chemicals, metals are neither created nor destroyed by biological
or chemical processes. However, these processes can transform metals from one
L. Contreras-Porcia et al.
constituents such as DNA/RNA, proteins, and lipids. To cope with heavy metal
excess, several mechanisms exist in tolerant seaweed species, including the activation of an efficient ROS-scavenging system constituted by metal-binding compounds, antioxidant enzymes, and oxygenated polyunsaturated fatty acids, among
others. Another adaptive mechanism involves the participation of ATP-binding
cassette (ABC) transporter proteins in translocating a wide variety of compounds
across cell membranes, including heavy metals. In contrast, an excessive heavy
metal presence can inhibit photosynthesis, reduce pigment concentration and growth,
induce cation losses, and disrupt gametophyte development in non-tolerant seaweed
species. In a scenario of lowered ocean pH and increased heavy metal toxicity, the
important roles played by non-tolerant seaweed species in structuring communities
could be severely compromised, with unknown consequences for associated organisms. Therefore, in the upcoming decades, marine pollution could majorly shift and
rearrange community compositions and the distributional ranges of species.
Keywords Seaweeds • Heavy metal stress • Tolerance mechanisms • Ocean
acidification
Contents
3.1 Heavy Metal Toxicity in Marine Ecosystems
36
3.2 Tolerance Mechanisms in Seaweeds to Heavy Metal Toxicity
38
3.3 Influence of Abiotic Factors on Metal Toxicity: The Case of the Ocean
Acidification
40
3.4 Seaweeds as a Study Model for Heavy Metal Toxicity and Ocean Acidification
42
3.5 Conclusion
44
References
44
3.1 Heavy Metal Toxicity in Marine Ecosystems
Heavy metals are significant toxic pollutants, and extensive literature details the accumulation of heavy metals in coastal marine ecosystems (Walker et al. 2012). Metals
are continuously released into the biosphere by volcanoes and the natural weathering
of rocks, in addition to release through numerous anthropogenic activities such as
mining, fuel combustion, and industrial, urban, and agricultural activities.
The input of metals into the sea, natural or anthropogenic in origin, is mainly via
the atmosphere, whereas the anthropogenic contribution of some metals (e.g., copper, cadmium, and lead) is greater than from natural sources (Duce et al. 1991).
Metal deposition occurs primarily through a gas exchange at the sea surface, through
either particle fallout (dry deposition) or through dragging from the air by rain (wet
deposition) (Walker et al. 2012).
Unlike organic chemicals, metals are neither created nor destroyed by biological
or chemical processes. However, these processes can transform metals from one
L. Contreras-Porcia et al.