Geochemical signature of land-based activities in Caribbean coral surface samples |
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Authors: | N G Prouty K A Hughen J Carilli |
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Institution: | (1) Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, 266 Woods Hole Rd., Woods Hole, MA 02543, USA;(2) US Geological Survey, Pacific Science Center, 400 Natural Bridges Dr., Santa Cruz, CA 95060, USA;(3) Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92093, USA |
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Abstract: | Anthropogenic threats, such as increased sedimentation, agrochemical run-off, coastal development, tourism, and overfishing,
are of great concern to the Mesoamerican Caribbean Reef System (MACR). Trace metals in corals can be used to quantify and
monitor the impact of these land-based activities. Surface coral samples from the MACR were investigated for trace metal signatures
resulting from relative differences in water quality. Samples were analyzed at three spatial scales (colony, reef, and regional)
as part of a hierarchical multi-scale survey. A primary goal of the paper is to elucidate the extrapolation of information
between fine-scale variation at the colony or reef scale and broad-scale patterns at the regional scale. Of the 18 metals
measured, five yielded statistical differences at the colony and/or reef scale, suggesting fine-scale spatial heterogeneity
not conducive to regional interpretation. Five metals yielded a statistical difference at the regional scale with an absence
of a statistical difference at either the colony or reef scale. These metals are barium (Ba), manganese (Mn), chromium (Cr),
copper (Cu), and antimony (Sb). The most robust geochemical indicators of land-based activities are coral Ba and Mn concentrations,
which are elevated in samples from the southern region of the Gulf of Honduras relative to those from the Turneffe Islands.
These findings are consistent with the occurrence of the most significant watersheds in the MACR from southern Belize to Honduras,
which contribute sediment-laden freshwater to the coastal zone primarily as a result of human alteration to the landscape
(e.g., deforestation and agricultural practices). Elevated levels of Cu and Sb were found in samples from Honduras and may
be linked to industrial shipping activities where copper–antimony additives are commonly used in antifouling paints. Results
from this study strongly demonstrate the impact of terrestrial runoff and anthropogenic activities on coastal water quality
in the MACR.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Communicated by Geology Editor Bernhard Riegl |
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Keywords: | Coral geochemistry Environmental proxies Belize Honduras Runoff Sedimentation |
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