A multiscale study of mercury transformations and dynamics at the chemocline of the Petit-Saut tropical reservoir (French Guiana)

ABSTRACT One year after impoundment in January 1994, methanotrophic bacteria in Petit Saut Reservoir (French Guiana) were active at the oxic-anoxic interface. This activity was revealed by the sudden extinction of diffusive methane emission (600 metric tons of CH4 · day−1 for the whole lake surface area, i.e., 360 km2). Lifting of inhibition was suspected. After reviewing the potential inhibitors of this physiological guild (O2, NH4 +, sulfides) and considering the similarities with nitrifiers, we suggest that sunlight influenced the methanotrophic bacteria. On the basis of phospholipid analysis, only a type II methanotrophic community was identified in the lake. Both growth and methanotrophic activity of an enriched culture, obtained in the laboratory, were largely inhibited by illumination over 150 microeinsteins · m−2 · s−1. These results were confirmed on a pure culture of Methylosinus trichosporium OB3B. In situ conditions showed that water transparency was quite stable in 1994 and 1995 and that the oxycline moved steadily deeper until January 1995. Considering the mean illumination profile during this period, we showed that removal of methanotrophic growth inhibition could only occur below a 2-m depth. The oxycline reached this level in October 1994, allowing methanotrophic bacteria to develop and to consume the entire methane emission 4 months later.

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Wildlife rescues—the case of the Petit Saut hydroelectric dam in French Guiana

Oryx ◽

10.1046/j.1365-3008.1999.00037.x ◽

1999 ◽

Vol 33 (2) ◽

pp. 115-126 ◽

Cited By ~ 73

Author(s):

Jean-Christophe Vié

Keyword(s):

Protected Area ◽

French Guiana ◽

Original Data ◽

Point Of View ◽

Biological Research ◽

The Past ◽

Hydroelectric Dam ◽

Ethical Point ◽

The Government ◽

Petit Saut

AbstractMany wildlife rescues have been carried out over the past few decades but most were not documented and were controversial. However, such operations can be useful, providing risks are evaluated and elementary guidelines are followed. In addition to saving lives and being desirable from an ethical point of view, such operations can be very valuable for both biological research and conservation, and are certainly preferable than the alternative: to do nothing. Previous rescues are reviewed and the operation conducted in French Guiana during the filling of the Petit Saut reservoir is described. Objectives, methods, results and financial aspects are discussed. Around 5500 mammals and reptiles were captured, sampled and translocated to a protected area. The successful results of the translocation, the large amount of original data obtained, the interest shown by scientists in our samples and the subsequent new conservation impetus that appeared in the government corroborate our initial conviction that the operation was worthwhile.

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Changes in bacterial and archaeal assemblages in an equatorial river induced by the water eutrophication of Petit Saut dam reservoir (French Guiana)

Aquatic Microbial Ecology ◽

10.3354/ame026209 ◽

2002 ◽

Vol 26 ◽

pp. 209-221 ◽

Cited By ~ 52

Author(s):

JF Dumestre ◽

EO Casamayor ◽

R Massana ◽

C Pedrós-Alió

Keyword(s):

French Guiana ◽

Dam Reservoir ◽

Petit Saut ◽

Water Eutrophication

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Phenotypic plasticity in fish life-history traits in two neotropical reservoirs: Petit-Saut Reservoir in French Guiana and Brokopondo Reservoir in Suriname

Neotropical Ichthyology ◽

10.1590/s1679-62252009000400018 ◽

2009 ◽

Vol 7 (4) ◽

pp. 683-692 ◽

Cited By ~ 17

Author(s):

Bernard de Mérona ◽

Jan Mol ◽

Régis Vigouroux ◽

Paulo de Tarso Chaves

Keyword(s):

Life History ◽

Phenotypic Plasticity ◽

Fish Species ◽

French Guiana ◽

Life History Traits ◽

Relative Length ◽

Maximum Length ◽

Batch Fecundity ◽

Long Time ◽

Petit Saut

Fish species are known for their large phenotypic plasticity in life-history traits in relation to environmental characteristics. Plasticity allows species to increase their fitness in a given environment. Here we examined the life-history response of fish species after an abrupt change in their environment caused by the damming of rivers. Two reservoirs of different age, both situated on the Guiana Shield, were investigated: the young Petit-Saut Reservoir in French Guiana (14 years) and the much older Brokopondo Reservoir in Suriname (44 years). Six life-history traits in 14 fish species were studied and compared to their value in the Sinnamary River prior to the completion of Petit-Saut Reservoir. The traits analyzed were maximum length, absolute and relative length at first maturation, proportion of mature oocytes in ripe gonad, batch fecundity and mean size of mature oocytes. The results revealed a general increase of reproductive effort. All species showed a decrease in maximum length. Compared to the values observed before the dam constructions, eight species had larger oocytes and three species showed an increased batch fecundity. These observed changes suggest a trend towards a pioneer strategy. The changes observed in Petit-Saut Reservoir also seemed to apply to the 30 years older Brokopondo Reservoir suggesting that these reservoirs remain in a state of immaturity for a long time.

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