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Baker D.M.,Cornell University | Baker D.M.,Carnegie Institution of Washington | Jordan-Dahlgren E.,Institute Ciencias Del Mar Y Limnologia Unam | Maldonado M.A.,Centro Ecologico Akumal | Harvell C.D.,Cornell University
Limnology and Oceanography | Year: 2010

We compared stable nitrogen isotope (δ15N) values from the common Caribbean sea fan Gorgonia ventalina, collected from a developed and undeveloped coastline, to test the hypothesis that sewage-derived nitrogen (N) inputs are detectable and more severe in developed areas along the Mesoamerican barrier reef of Mexico. The Akumal coast was selected as the developed site since this area is inhabited by thousands of local residents and has a significant flux of tourists; it was compared to a relatively undeveloped shoreline south of Mahahual, a small town with a few hundred residents and sewage treatment infrastructure. Gorgonians sampled from Akumal were relatively enriched in δ15N (as high as 7.7% nearshore) and were ∼ 3.5‰ greater than sea fans from Mahahual collected at similar depths. While previous work has shown that water column N concentrations are uniform around Akumal, δ15N values of sea fans sampled parallel to shore were variable, indicating that sewage-derived N inputs are spotty along the coast. δ15N values were positively correlated with fecal Enterococcus counts from seawater, confirming that these enrichments are associated with sewage and not denitrification. We suggest that the data from Mahahual can be used as an isotopic baseline for monitoring the Mesoamerican barrier reef at sites where increased development is planned or underway. © 2010, by the American Society of Limnology and Oceanography, Inc.


Vidal Hernandez L.E.,Institute Ciencias Del Mar Y Limnologia Unam | Paramo Romero I.,Cedro and 4 Residencial La Arboleda | Soto L.A.,Institute Ciencias Del Mar Y Limnologia Unam | Rivera Arriaga E.,Institute Ecologia Pesquerias Y Oceanografia Del Golfo Of Mexico
Ocean and Coastal Management | Year: 2012

In general, the assessment of the environmental impact of fossil oil exploration and exploitation is related to pollution, particularly to oil spills. However, this is a limited view of the implications of the problem because there are other deleterious effects that are assumed to be assimilated by the resilient capacity of the marine environment. However, some criteria to evaluate and cope with these additional effects have emerged and should be incorporated into the legislation of such activities. This rationale is applied to oil exploration and exploitation in the southwest of the Gulf of Mexico. The aim is to contribute to the development of a regional framework for the sustainable management of marine water natural resources. An analysis of 10 criteria and 38 attributes of sustainability and impacts caused by this activity were applied here to 26 Mexican legislative instruments. Cluster and multivariate analyses were performed to map the interrelations among legal instruments. The results show a failure of 51-92% to control marine impacts from marine oil drilling and exploitation. Attributes that should be reinforced in the already existing Mexican legal framework include seismic surveys, explosion control, oil pipe networks, oil rig deployment, dredging, channel opening, and ballast water discharge. Moreover, two of these key legal Instruments regulating oil offshore environmental impacts need to be improved: Norm 149-SEMARNAT-2006 and the Environmental Impact Assessment regional guidelines. © 2011 Elsevier Ltd.

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