Silvia G. De Marco

The burrowing crab Neohelice granulata as potential bioindicator of heavy metals in estuarine systems of the Atlantic coast of Argentina.

This paper presents the concentrations of total copper, lead, cadmium, and zinc in hepatopancreas of the burrowing crab Neohelice granulata from the Samborombón Bay (La Plata River estuary) and the Mar Chiquita coastal lagoon, Argentina. The highest accumulation of lead was observed in Mar Chiquita samples, whereas copper, zinc, and cadmium concentrations were higher in those from Samborombón Bay. Marked temporal and geographic availability differences were observed, while sexual differences only were observed for zinc. Finally, the validity of using this species as bioindicator of heavy-metal pollution within the assessed estuarine ecosystems is discussed.

Mercury distribution in estuarine environments from Argentina: the detoxification and recovery of salt marshes after 15 years

Total Hg contents from abiotic (surface sediments and suspendedparticulate matter) and biological (crabs, fishes and halophytes)compartments from Bahía Blanca estuary and Mar Chiquita CoastalLagoon, Argentina, have been monitored since the 1980s. At BahíaBlanca estuary, high Hg concentrations were recorded during the early1980s in surface sediments (0.34 ± 0.22 μg/g) andsuspended particulate matter (0.19 ± 0.10 μg/g). Fishspecies, Mustelus schmitti (0.89 ± 0.29 μg/g), Paralichthys brasiliensis (0.85 ± 0.18 μg/g) and Micropogonias furnieri (0.37 ± 0.11 μg/g) also presentedhigh Hg concentrations. The large industrial nucleus located within theestuary has been identified as the main metal source for this environment.Hg contents from the same area during 1996–1998 were significantlylower: surface sediments (0.164 ± 0.023 μg/g), suspendedparticulate matter (0.048 ± 0.0017 μg/g), fish Micropogonias furnieri (0.13 ± 0.02 μg/g) and crab Chasmagnathus granulata (0.334 ± 0.071 μg/g). This trendof environmental detoxification is probably related with (i) thetechnological changes incorporated by the local industry, (ii) a mostadequate management of industrial effluents, and (iii) the removal ofgreat sediment volume by dredging and refill.During the 1980s Mar Chiquita Lagoon Hg concentrations reached 0.08± 0.01 μg/g in surface sediments and 0.09 ±0.025 μg/g in suspended particulate matter, and 0.14 ±0.04 μg/g in the fish Basilichthys bonariensis and 0.22 ±0.08 μg/g in Paralichthys brasiliensis, and 0.08 ±0.01 μg/g in the crab C. granulata, Hg concentrations werelower than at Bahía Blanca. Remote Hg sources for this Coastal Lagoonand atmospheric and stream transport of Hg is proposed as major Hgsources, since no Hg point sources exists nearby. Mercury concentrationsrecorded in the 1996–1998 period were lower than those recorded inthe previous decade: surface sediments (0.019 ± 0.004 μg/g), suspended particulate matter (0.030 ± 0.008 μg/g), halophyte Spartina densiflora (0.013 ± 0.008 μg/g) or crab C. granulata (0.011 ± 0.009 μg/g).Both Hg bioaccumulation and biomagnification processes were verified inBahía Blanca estuary and in Mar Chiquita Coastal Lagoon. This apparentrecovery of both estuarine environments deserves to be carefully analyzed,in order to fully understand the foundations of these processes.

Effects of zinc on molting and body weight of the estuarine crab Neohelice granulata (Brachyura: Varunidae)

The semiterrestrial burrowing crab Neohelice granulata is one of the main inhabitants of the supratidal and intertidal zones of brackish salt marshes, estuaries and coastal lagoons from South Americas Atlantic littoral. A large population of this species spreads out Mar Chiquita coastal lagoon (in Argentina) and its corresponding wetlands, and is considered as a key species within this system. Since high values of dissolved heavy metals (including Zn) have been recently reported within Mar Chiquita coastal lagoon, with levels unusually higher than those from other coastal systems within Argentina, it has been explored that the existence of a risk of environmental conditions endanger these populations. So, juveniles of this estuarine crab were experimentally exposed to increasing concentrations of dissolved Zn (i.e., 0, 0.5 and 1 mg Zn(2+)L(-1)) during six months, the time involved between two successive molts; in addition, both the size and weight reached after each molt were also studied in this assay. It can be concluded that zinc can be toxic to crabs only at high concentrations. Considering that levels up to 1 mg ZnL(-1) were recently reported in Mar Chiquita coastal lagoon waters, the potential occurrence of mean chronic effects on the crab population within the coastal lagoon is discussed.

Phytoplankton dynamic in mar chiquita coastal lagoon (Argentina), and its relationship with potential nutrient sources

Abstract The concentration and distribution of nutrients (nitrate, nitrite, phosphate, silicate) in water, photosynthetic pigments (chlorophyll a and phaeopigments) in suspended particulate matter (SPM), and phytoplankton from Mar Chiquita Coastal Lagoon, in Argentina, was studied along six (6) sampling stations during a year in order to know their spatial and temporal variations. Internationally standardized analytical methods were applied in order to reach these objectives. The use of soils for farming and continental runoff of the adjacent terrestrial systems close to the coastal lagoon seemed to be a significant nutrient source for this water body, which is able to support its own dynamic of phytoplankton within this water body. Results obtained regarding nutrient and pigment distribution allowed the identification of two different systems within the coastal lagoon: one under marine influence and the other under inland influence, with different ecological and environmental characteristics. Temporal trends of the corresponding phytoplankton development have been identified, and it has been observed that the biological production which occurred within the coastal lagoon along the whole year was higher than corresponding ones from other coastal environments in Argentina. Moreover, nutrient occurrence within the internal region favored the development of the highest biomass detected within the whole lagoon. The system seems to function as a transition zone, which profits from unusual nutrient inputs, together with other environmental conditions (salinity, temperature), bringing continuous nutrient availability for phytoplankton and consequently food supply for marine and estuarine organisms.

Chapter 1: Ancient vs. Modern Oceans: Perspectives in a Climate Change Scenario

Fil: Palma, Elbio Daniel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Instituto Argentino de Oceanografia. Universidad Nacional del Sur. Instituto Argentino de Oceanografia; Argentina