Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean

• Published in: Environmental research Vol. 146; pp. 263 - 273
• Main Authors: Dirtu, Alin C., Malarvannan, Govindan, Das, Krishna, Dulau-Drouot, Violaine, Kiszka, Jeremy J., Lepoint, Gilles, Mongin, Philippe, Covaci, Adrian
• Format: Journal Article Web Resource
• Language: English
• Published: Netherlands Elsevier Inc 01-04-2016; Academic Press
• Subjects: Adipose Tissue - chemistry; Animals; AQUATIC ECOSYSTEMS; Aquatic sciences & oceanology; Bottle-Nosed Dolphin - physiology; BUILDUP; CARBON 13; CETACEANS; COASTAL WATERS; CONCENTRATION RATIO; Contaminants; Contamination; DDT; Dolphins; Ecosystem; Environmental Exposure; Environmental Monitoring; ENVIRONMENTAL SCIENCES; Environmental sciences & ecology; Feeding Behavior; Halogenated Diphenyl Ethers - metabolism; Hydrocarbons, Chlorinated - metabolism; Indian Ocean; La Réunion; Life sciences; Marine; marine mammals; MERCURY; Mercury (metal); Mercury - metabolism; Muscles; NITROGEN 15; PHENYL ETHER; POLLUTANTS; POLYCHLORINATED BIPHENYLS; Polychlorinated Biphenyls - metabolism; POPs; Reunion; Sciences aquatiques & océanologie; Sciences de l’environnement & écologie; Sciences du vivant; Skin - chemistry; Species Specificity; Spinners; stable isotopes; Stenella - physiology; Stenella longirostris; Teleostei; Tursiops aduncus; Water Pollutants, Chemical - metabolism; Reunion; Indian Ocean; I, Indo-Pacific; ISW, Indian Ocean, Mascarene Is., Reunion; La Réunion; stable isotopes; Tursiops aduncus; Stenella longirostris; POPs; Hg
• ISSN: 0013-9351; 1096-0953; 1096-0953
• DOI: 10.1016/j.envres.2016.01.006

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ13C and δ15N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ15N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation.
•POPs and total Hg were measured in spinner and bottlenose dolphins from La Réunion.•Levels of PCBs, PBDEs and T-Hg were lower in spinner than in bottlenose dolphins.•Contrasted contaminant profiles were observed between the two dolphin species.•Profiles are most likely explained by dietary and foraging habitat preferences.