Wells, J. W., 1982. Fossil coral from Midway Atoll. US Geological
Survey Professional Paper, 680, 1–7.
Wilson, J. T., 1963. A possible origin of the Hawaiian Islands.
Canadian Journal of Physics, 41, 863–870.
Cross-references
Climate Change: Impact of Sea Level Rise on Reef Flat Zonation
and Productivity
Climate Change: Increasing Storm Activity
Darwin Point
Density and Porosity: Influence on Reef Accretion Rates
Midway Atoll (Hawaiian Archipelago)
Ocean Acidification, Effects on Calcification
Oceanic Hotspots
Pacific Coral Reefs: An Introduction
Submerged Reefs
HEAVY METAL ACCUMULATION IN
SCLERACTINIAN CORALS
Sofia Shah, Edward Lovell
University of South Pacific, Suva, Fiji
Synonyms
Heavy metals are also referred to as trace metals or trace
elements
Definition
Heavy metals are metals and metalloids, which have
atomic weights between 63.5 and 200.6 g/mol and density > 4.5 g/cm
3 (Shah, 2008). Heavy metals are conservative in nature as they persist in the environment for longer
periods. Heavy metals are both naturally occurring and
anthropogenically introduced in the marine environment
and are toxic to both aquatic biota and humans at low
concentrations.
Heavy metals in the marine environment
Elevated concentrations of the heavy metals are the consequence of effluent discharge, urban stormwater, sewage
pollution, harbor dredging, sedimentation, and agricultural and industrial runoff. According to Al-Rousan et al.
(2007), these heavy metals occur in the coral skeletons
as a result of structural incorporation of metals into the
aragonite (Goreau, 1977), inclusion of particulate materials in skeletal cavities (reviewed by Howard and Brown,
1984), surface adsorption onto exposed skeleton (St. John,
1974; Brown et al., 1991), and chelation with the organic
matrix of the skeleton (Mitterer, 1978). Once incorporated
into the coral skeleton, the metals will remain embedded
forever since the new growth covers the old carbonate surface (St. John, 1974).
This study
The metals of interest in this study were copper (Cu), zinc
(Zn), lead (Pb), cadmium (Cd), and iron (Fe). Cu, Zn, and
Fe were of particular interest as they are the essential elements required for growth of organisms as well as
humans. On the other hand, Cd and Pb, being the nonessential elements, are harmful to the marine organisms
due to their polluting effects and toxicity. The concentrations of these metals together with the partitioning of these
metals in the skeleton, tissue, and zooxanthellae of three
different coral families were looked into. Heavy metal
accumulation rates were also studied in the three different
families for a 5-day period. Coral samples were taken from
three different sites, namely reefs encountering significant
terrigenous inputs from rivers, fringing reefs (with a chain
of hotels), and a pristine reef.
Scleractinian corals
Scleractinian corals are the architects of coral reefs and
hence good indicators of environmental changes due to
the fact that their skeletons assimilate records of the presence and concentrations of certain metals over centuries
(Esslemont, 1999). Scleractinian corals incorporate the
trace elements (or heavy metals) in their living parts and
skeletons. Acropora formosa, Pocillopora damicornis,
and Porites spp. were studied for heavy metal
concentrations.
Outcomes
High metal concentrations were determined for the zooxanthellae, than the tissue and the skeleton, suggesting
that the zooxanthellae are responsible for the metal uptake
in corals. Reichelt-Brushett and McOrist (2003) suggest
that symbiotic zooxanthellae play an important role in
the accumulation and regulation of trace metals. The variation among the three different families of corals suggests
that Porites spp. tend to accumulate lower concentrations
of heavy metals than the other two species studied.
Scleractinian corals in pristine environments recorded
a lower metal concentration than those obtained from
fringing reefs and reefs closer to significant terrigenous
inputs.
Fe and Pd were found to be in higher concentrations
than Cu, Zn, and Cd at all the study sites. The most probable reason that Fe reaches the marine environment is
through suspended sediments and aeolian dust. Fringing
reefs and reefs near terrigenous inputs have constant influences of suspended sediments and hence it is most likely
that Fe enters the marine environment through this means.
High concentrations of lead in the samples were mostly
from sewer outfall, industrial discharge, and agricultural/
storm water runoff and wastes discharged from hotels
and piggery farms.
Dose-response curves from the bioassays showed that
as the nominal concentrations increase, the heavy metal
uptake in corals also increases. Zooxanthellae were lost
to the aquaria water as a result of stress on the corals. High
concentrations of Pb and Fe were accumulated in the
corals for each dosage period.
HEAVY METAL ACCUMULATION IN SCLERACTINIAN CORALS
553
Survey Professional Paper, 680, 1–7.
Wilson, J. T., 1963. A possible origin of the Hawaiian Islands.
Canadian Journal of Physics, 41, 863–870.
Cross-references
Climate Change: Impact of Sea Level Rise on Reef Flat Zonation
and Productivity
Climate Change: Increasing Storm Activity
Darwin Point
Density and Porosity: Influence on Reef Accretion Rates
Midway Atoll (Hawaiian Archipelago)
Ocean Acidification, Effects on Calcification
Oceanic Hotspots
Pacific Coral Reefs: An Introduction
Submerged Reefs
HEAVY METAL ACCUMULATION IN
SCLERACTINIAN CORALS
Sofia Shah, Edward Lovell
University of South Pacific, Suva, Fiji
Synonyms
Heavy metals are also referred to as trace metals or trace
elements
Definition
Heavy metals are metals and metalloids, which have
atomic weights between 63.5 and 200.6 g/mol and density > 4.5 g/cm
3 (Shah, 2008). Heavy metals are conservative in nature as they persist in the environment for longer
periods. Heavy metals are both naturally occurring and
anthropogenically introduced in the marine environment
and are toxic to both aquatic biota and humans at low
concentrations.
Heavy metals in the marine environment
Elevated concentrations of the heavy metals are the consequence of effluent discharge, urban stormwater, sewage
pollution, harbor dredging, sedimentation, and agricultural and industrial runoff. According to Al-Rousan et al.
(2007), these heavy metals occur in the coral skeletons
as a result of structural incorporation of metals into the
aragonite (Goreau, 1977), inclusion of particulate materials in skeletal cavities (reviewed by Howard and Brown,
1984), surface adsorption onto exposed skeleton (St. John,
1974; Brown et al., 1991), and chelation with the organic
matrix of the skeleton (Mitterer, 1978). Once incorporated
into the coral skeleton, the metals will remain embedded
forever since the new growth covers the old carbonate surface (St. John, 1974).
This study
The metals of interest in this study were copper (Cu), zinc
(Zn), lead (Pb), cadmium (Cd), and iron (Fe). Cu, Zn, and
Fe were of particular interest as they are the essential elements required for growth of organisms as well as
humans. On the other hand, Cd and Pb, being the nonessential elements, are harmful to the marine organisms
due to their polluting effects and toxicity. The concentrations of these metals together with the partitioning of these
metals in the skeleton, tissue, and zooxanthellae of three
different coral families were looked into. Heavy metal
accumulation rates were also studied in the three different
families for a 5-day period. Coral samples were taken from
three different sites, namely reefs encountering significant
terrigenous inputs from rivers, fringing reefs (with a chain
of hotels), and a pristine reef.
Scleractinian corals
Scleractinian corals are the architects of coral reefs and
hence good indicators of environmental changes due to
the fact that their skeletons assimilate records of the presence and concentrations of certain metals over centuries
(Esslemont, 1999). Scleractinian corals incorporate the
trace elements (or heavy metals) in their living parts and
skeletons. Acropora formosa, Pocillopora damicornis,
and Porites spp. were studied for heavy metal
concentrations.
Outcomes
High metal concentrations were determined for the zooxanthellae, than the tissue and the skeleton, suggesting
that the zooxanthellae are responsible for the metal uptake
in corals. Reichelt-Brushett and McOrist (2003) suggest
that symbiotic zooxanthellae play an important role in
the accumulation and regulation of trace metals. The variation among the three different families of corals suggests
that Porites spp. tend to accumulate lower concentrations
of heavy metals than the other two species studied.
Scleractinian corals in pristine environments recorded
a lower metal concentration than those obtained from
fringing reefs and reefs closer to significant terrigenous
inputs.
Fe and Pd were found to be in higher concentrations
than Cu, Zn, and Cd at all the study sites. The most probable reason that Fe reaches the marine environment is
through suspended sediments and aeolian dust. Fringing
reefs and reefs near terrigenous inputs have constant influences of suspended sediments and hence it is most likely
that Fe enters the marine environment through this means.
High concentrations of lead in the samples were mostly
from sewer outfall, industrial discharge, and agricultural/
storm water runoff and wastes discharged from hotels
and piggery farms.
Dose-response curves from the bioassays showed that
as the nominal concentrations increase, the heavy metal
uptake in corals also increases. Zooxanthellae were lost
to the aquaria water as a result of stress on the corals. High
concentrations of Pb and Fe were accumulated in the
corals for each dosage period.
HEAVY METAL ACCUMULATION IN SCLERACTINIAN CORALS
553