Mangrove dynamics in the southwestern Caribbean since the 'Little Ice Age': A history of human and natural disturbances

Relatively little is known about the long-term response of Caribbean mangroves to human and natural disturbances during the 'Little Ice Age' (LIA). We present new palynological information on the dynamics of the Bahia Honda mangrove from the eastern coast of San Andres Island in the southwestern Caribbean for the late Holocene. Major changes in the Bahia Honda pollen record show the combined effects of natural events (strong storms and sea-level rise), and human disturbances. These changes are supported by 14C dates, sedimentological and palynological information. A storm (most probably a hurricane) was recorded around AD 1600, caused sediment reworking and the subsequent loss of about 2000 years of the vegetation record. The devastation of tree vegetation by this event allowed the expansion of heliophytic vegetation (e.g. grasses and vines). Mangroves and coastal vegetation started to recover at AD 1700, reaching their maximum extent within a few decades, when microforaminifera shells became abundant at the coring site, thus suggesting a relative sea-level rise because of the geomorphic reconfiguration of the coastal plain after the storm. Furthermore, the pollen evidence indicates more humid regional climates during the late LIA (AD 1700-1850). Mangrove and coastal vegetation declined sharply as a consequence of the establishment of coconut plantations around AD 1850. The recovery of the mangroves after AD 1960 is a result of the combined effect of relative sea-level rise and drastic changes in the local economy from coconut plantations to commerce. © 2010 The Author(s)

Chemical contamination assessment in mangrove-lined Caribbean coastal systems using the oyster Crassostrea rhizophorae as biomonitor species

This paper aims to contribute to the use of mangrove cupped oyster, Crassostrea rhizophorae, as a biomonitor species for chemical contamination assessment in mangrove-lined Caribbean coastal systems. Sampling was carried out in eight localities (three in Nicaragua and five in Colombia) with different types and levels of contamination. Oysters were collected during the rainy and dry seasons of 2012–2013 and the tissue concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) were determined. Low tissue concentrations of metals (except Hg) and PAHs; moderate-to-high tissue concentrations of Hg, hexachlorocyclohexanes (HCHs), and dichlorodiphenyl-trichloroethanes (DDTs); detectable levels of chlorpyrifos, polychlorinated biphenyls (PCBs) (mainly CB28, CB118, CB138 and CB 153) and brominated diphenyl ethers 85 (BDE85); and negligible levels of musks were recorded in Nicaraguan oysters. A distinct profile of POPs was identified in Colombia, where the tissue concentrations of PCBs and synthetic musk fragrances were low to moderate, and Ag, As, Cd, Pb, and PAHs ranged from moderate to extremely high. Overall, the values recorded for HCHs, DDTs and PCBs in Nicaraguan mangrove cupped oysters greatly exceeded the reference values in tissues of C. rhizophorae from the Wider Caribbean Region, whereas only the levels of PCBs were occasionally surpassed in Colombia. Different contaminant profiles were distinguished between oysters from Nicaragua and Colombia in radar plots constructed using the main groups of contaminants (metals, PAHs, musks, PCBs, and organochlorine pesticides (OCPs)). Likewise, integrated pollution indices revealed differences in the levels of contaminants. Moreover, the profiles and levels in oyster tissues also varied with season. Thus, principal component analysis clearly discriminated Nicaraguan and Colombian localities and, especially in Colombia, seasonal trends in chemical contamination and differences amongst localities were evidenced. The geographical and environmental disparity of the studied scenarios may represent to a large extent the diversity of mangrove-lined Caribbean coastal systems and therefore the present results support the use of C. rhizophorae as suitable biomonitor species at Caribbean regional scale, where seasonal variability is a major factor controlling pollutant mobility and bioavailability