Mercury contamination level and speciation inventory in Lakes Titicaca & Uru-Uru (Bolivia): Current status and future trends.

Aquatic ecosystems of the Bolivian Altiplano (∼3800 m a.s.l.) are characterized by extreme hydro-climatic constrains (e.g., high UV-radiations and low oxygen) and are under the pressure of increasing anthropogenic activities, unregulated mining, agricultural and urban development. We report here a complete inventory of mercury (Hg) levels and speciation in the water column, atmosphere, sediment and key sentinel organisms (i.e., plankton, fish and birds) of two endorheic Lakes of the same watershed differing with respect to their size, eutrophication and contamination levels. Total Hg (THg) and monomethylmercury (MMHg) concentrations in filtered water and sediment of Lake Titicaca are in the lowest range of reported levels in other large lakes worldwide. Downstream, Hg levels are 3-10 times higher in the shallow eutrophic Lake Uru-Uru than in Lake Titicaca due to high Hg inputs from the surrounding mining region. High percentages of MMHg were found in the filtered and unfiltered water rising up from <1 to ∼50% THg from the oligo/hetero-trophic Lake Titicaca to the eutrophic Lake Uru-Uru. Such high %MMHg is explained by a high in situ MMHg production in relation to the sulfate rich substrate, the low oxygen levels of the water column, and the stabilization of MMHg due to abundant ligands present in these alkaline waters. Differences in MMHg concentrations in water and sediments compartments between Lake Titicaca and Uru-Uru were found to mirror the offset in MMHg levels that also exist in their respective food webs. This suggests that in situ MMHg baseline production is likely the main factor controlling MMHg levels in fish species consumed by the local population. Finally, the increase of anthropogenic pressure in Lake Titicaca may probably enhance eutrophication processes which favor MMHg production and thus accumulation in water and biota.

Low total mercury in Caiman yacare (Alligatoridae) as compared to carnivorous, and non-carnivorous fish consumed by Amazonian indigenous communities.

Mercury contamination in the River Beni basin is an important health risk factor, primarily for indigenous communities that live along the river. Among them are the Tacana, living in their original territory with sustainable use of their natural resources, consuming fish, Caiman yacare, and other riverine resources as their main source of protein. To assess mercury exposure to Tacana people, total mercury (THg) was evaluated in the muscle of seven commercial fish, and Caiman yacare (yacare caiman) during 2007 and 2008. THg was extracted by acid digestion and concentrations were determined by atomic absorption spectrometry. Mean mercury concentrations in C. yacare was 0.21 ± 0.22 µg g-1Hg w.w. (wet weight), which is lower than expected given its high trophic level, and its long life-span. It is possible that mercury in C. yacare is accumulated in other organs, not included in this study; but it is also possible that physiological mechanisms are involved that help caimans get rid of ingested mercury, or simply that C. yacare's diverse diet reduces THg accumulation. Carnivorous fishes (Pygocentrus nattereri, Pseudoplatystoma tigrinum, Zungaro zungaro, Plagioscion squamosissimus, and Leiarius marmoratus) had the highest total mercury concentrations, ranging from 0.35 to 1.27 µg g-1Hg w.w. moreover, most were above the limit recommended by WHO (0.5 µg g-1Hg w.w.); except for Leiarius marmuratus, which presented a mean of 0.353 ± 0.322 µg g-1Hg w.w. The two non-carnivorous fish species (Prochilodus nigricans, and Piaractus brachypomus) present mean concentrations of 0.099 ± 0.027, and 0.041 ± 0.019 µg g-1Hg w.w., respectively. Finally, recommendations on the consumption habits of Tacana communities are discussed.

Contribution to the knowledge of the andean stonefly genus Claudioperla illies, with description of new apterous and micropterous species (Plecoptera: Gripopterygidae).

The genus Claudioperla (Plecoptera: Gripopterygidae), which has been reported from Chile and Argentina to Colombia, was until now monospecific. The study of adults from various localities of the Bolivian Altiplano has resulted in the discovery of four distinct species. Three are new and described: Claudioperla rosalesi n. sp., Claudioperla moyai n. sp., and Claudioperla ruhieri n. sp. The fourth, Claudioperla tigrina (Klapálek), presents morphological variations with previous descriptions that are exposed and discussed. One of the new species, C. ruhieri, is apterous. The male of C. moyai is micropterous. Among South American stoneflies, they are the first cases of aptery and microptery reported outside of Patagonia. Adapted to extreme conditions of temperature and altitude, C. moyai and C. ruhieri are particularly threatened by the recent evolution of Bolivian glaciers.

Levels of soluble ICAM-1 and soluble IL-2R in the serum and aqueous humor of uveitis patients.

PURPOSE: To study the ocular and systemic behaviour of the immune activation markers soluble ICAM-1 and soluble IL-2R in patients with active uveitis. METHODS: We determined the levels of soluble ICAM-1 and soluble IL-2R in the aqueous humor and peripheral blood of 23 patients with active uveitis and 16 age and gender matched controls (who were to undergo cataract extraction) by means of ELISA enzyme immunoanalysis. RESULTS: Patients with uveitis presented higher levels of soluble ICAM-1 and soluble IL-2R in the aqueous humor and peripheral blood. Comparison of the aqueous humor and peripheral blood revealed higher levels of soluble ICAM-1 in the aqueous humor, while we found no differences for soluble IL-2R. Analysis of the clinical characteristics of the uveitis we studied showed no differences in the levels of these markers in either blood or aqueous humor. CONCLUSIONS: The finding of elevated levels of soluble IL-2R and soluble ICAM-1 in the aqueous humor and peripheral blood of patients with uveitis suggests the local and systemic participation of these markers in the pathogenesis of uveitis.