Prospective biomonitor and sentinel bivalve species for pollution monitoring and ecosystem health disturbance assessment in mangrove-lined Nicaraguan coasts

Abstract

This research aims at contributing to the use of Polymesoda arctata, Anadara tuberculosa, and Larkinia grandis as prospective biomonitors and sentinels, surrogate of Crassostrea rhizophorae for pollution biomonitoring in mangrove-lined coastal systems. Localities were selected along the Nicaraguan coastline in the rainy and dry seasons during 2012-2013: A. tuberculosa and L. grandis were collected in the Pacific, and P. arctata in the Caribbean. The tissue concentration of metals, polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants (POPs) were integrated into pollution indices (chemical pollution index -CPI- and pollution load index -PLI-) and biological endpoints (flesh-condition, reproduction, histopathology and stress-on-stress) were determined as biomarkers of ecosystem health disturbance. In the Caribbean, contaminant tissue concentration was low in P. arctata, with some exceptions. Ag, As, Cd, Hg, Ni and V were mainly recorded during dry season, and PAHs and POPs (HCHs, DDTs, AHTN, PCBs and BDE85) during rainy season. Metals and PAHs were not a major threat in the study area; in contrast, high levels of HCHs and DDTs and low-to-moderate levels of musk fragrances and PBDEs were recorded. Minor differences were found in biological parameters albeit during the rainy season the LT50 values were low and seemingly associated to high PLI and CPI values. In the Pacific, the main pollutants recorded in A. tuberculosa and L. grandis were HCHs, DDTs, AHTN and PDBEs in rainy season and Cd in dry season. Although basic research is needed to understand the general biology, ecology and diseases in these Pacific species, biological endpoints comparable to those used in other sentinel bivalves are seemingly suitable biomarkers of health disturbance. Overall, Caribbean P. arctata and Pacific A. tuberculosa and L. grandis seem to be potential target species for pollution monitoring and ecosystem health disturbance assessment in mangrove-lined Nicaraguan coastal systems. Their use together with C. rhizophorae would provide opportunities for common approaches to be applied in inter-ocean countries of the Mesoamerican region.

Keywords: Bioaccumulation; Biomarkers; Ecosystem health; Mangrove; Monitoring.