Marcela Gerpe

Plastic ingestion in Franciscana dolphins, Pontoporia blainvillei (Gervais and d’Orbigny, 1844), from Argentina

Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) incidentally captured in artisanal fisheries of the northern coast of Argentina. Twenty-eight percent of the dolphins presented PD in their stomach, but no ulcerations or obstructions were recorded in the digestive tracts. PD ingestion was more frequent in estuarine (34.6%) than in marine (19.2%) environments, but the type of debris was similar. Packaging debris (cellophane, bags, and bands) was found in 64.3% of the dolphins, with a lesser proportion (35.7%) ingesting fishery gear fragments (monofilament lines, ropes, and nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina.

Lethal and sublethal effects of cadmium in the white shrimp Palaemonetes argentinus: A comparison between populations from contaminated and reference sites

In the present study, the acute toxicity of cadmium (Cd) in white shrimp (Palaemonetes argentinus) from a metal polluted lagoon (Los Padres, LP) and from unpolluted lagoon (Nahuel Ruca, NR) was evaluated. Both population, were exposed to 3.06, 12.26, 30.66, 61.32, 306 and 613.2 μg Cd · L(-1) for 96-h. The sublethal effects of Cd were examined by two cellular biomarkers: metallothionein (MT) and lipid peroxidation (LPO). The seasonal variations of biomarkers in both lagoons were also evaluated. P. argentinus demonstrated a high sensitivity to Cd, with values of 96-h LC50 lower and close to those of highly sensitive species; therefore, can be proposed as a good indicator species. The LC(50) values of shrimp from LP (24-h: 269.8, 48-h: 67.45, 72-h: 30.66, 96-h: 24.50 μg Cd · L(-1)) were higher than those from NR (24-h: 153.3, 48-h: 32.65, 72-h: 18.40, 96-h: 12.26 μg Cd · L(-1)), indicating a higher tolerance to Cd, and it was related to their origin. Differential responses in terms of MT induction and LPO between populations were also detected. In NR shrimps, the MT synthesis was induced very fast (24-h) and even at the minimum concentration tested (3.06 μg Cd · L(-1)), while no increases were observed in LPO levels. In contrast, the MT and LPO levels in LP shrimps were not increased relative to control, although they were more tolerant to Cd than those of NR; suggesting the presence of another mechanism involved in the detoxification of Cd. The differences in both sensitivity and biochemical responses to Cd may be related with their environmental histories.

Fine scale distribution constrains cadmium accumulation rates in two geographical groups of Franciscana dolphin from Argentina.

Franciscana dolphin is an endemic cetacean in the southwestern Atlantic Ocean and is classified as Vulnerable A3d by the International Union for Conservation of Nature. Cadmium accumulation was assessed in two geographic groups from Argentina; one inhabits the La Plata River estuary, a high anthropogenic impacted environment, and the other is distributed in marine coastal, with negligible pollution. Despite the environment, marine dolphins showed an increase of renal Cd concentrations since trophic independence; while in estuarine dolphins was from 6 years. This is associated with dietary Argentine anchovy which was absent in the diet of estuarine dolphins, being a trophic vector of cadmium in shelf waters of Argentina. Cluster analysis also showed high levels of cd in association with the presence of anchovy in the stomach. The difference in the fine scale distribution of species influences dietary exposure to Cd and, along with other data, indicates two stocks in Argentina.

Metallothioneins pattern during ontogeny of coastal dolphin, Pontoporia blainvillei, from Argentina

Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation.