Pierre Denis Plisnier - Academia.edu (original) (raw)
Papers by Pierre Denis Plisnier
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Scientific Data
Climate change and other anthropogenic stressors have led to long-term changes in the thermal str... more Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of...
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Measurement, Analysis, Simulation, 2003
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Hydrobiologia, 1996
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Scientific Reports
Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but c... more Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either s...
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Aquatic Ecosystem Health & Management
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Ecological Indicators
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Journal of Hydrometeorology
Accurate precipitation data are fundamental for understanding and mitigating the disastrous effec... more Accurate precipitation data are fundamental for understanding and mitigating the disastrous effects of many natural hazards in mountainous areas. Floods and landslides, in particular, are potentially deadly events that can be mitigated with advanced warning, but accurate forecasts require timely estimation of precipitation, which is problematic in regions such as tropical Africa with limited gauge measurements. Satellite rainfall estimates (SREs) are of great value in such areas, but rigorous validation is required to identify the uncertainties linked to SREs for hazard applications. This paper presents results of an unprecedented record of gauge data in the western branch of the East African Rift, with temporal resolutions ranging from 30 min to 24 h and records from 1998 to 2018. These data were used to validate the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) research version and near-real-time products for 3-hourly, daily, and monthly r...
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Journal of Great Lakes Research
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ABSTRACT
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In this study, I've looked at the zooplankton variability and distribution at night near the ... more In this study, I've looked at the zooplankton variability and distribution at night near the fishing canoes, and tried to correlate these findings to the total fish catch and catch composition. Zooplankton was collected at the surface and from 100 to 0m at two locations: right from the fishermen's boat and about 100m from it. The samples were compared to
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Lake Tanganyika harbors a simple pelagic zooplankton community in terms of species abundance. The... more Lake Tanganyika harbors a simple pelagic zooplankton community in terms of species abundance. The micro and meso zooplankton communities consist primarily of one calanoid species, three cyclopoid species, while the macrozooplankton community consist of 15 species of shrimp, one species of medusa and two primary species of fish larvae (Coulter, 1991). The zooplankton community is an important indicator of primary
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ABSTRACT
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Encyclopedia of Earth Sciences Series, 2012
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Encyclopedia of Earth Sciences Series, 2012
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Biogeosciences, 2007
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Biogeosciences Discussions, 2006
Biogenic productivity of Lake Tanganyika is highly dependent on seasonal upwellings of anoxic dee... more Biogenic productivity of Lake Tanganyika is highly dependent on seasonal upwellings of anoxic deep waters. We investigated the shell of freshwater bivalve Pleiodon spekii as a geochemical archive of these periodic hydrological changes tuned by the monsoon regime. The results of a 2-years-long geochemical survey of the coastal waters performed on the dissolved and particulate fractions were put in perspective against laser ablation ICP-MS profiles of Mn in five aragonitic shells from the same lake location. Skeletal Mn profiles in 3 shells are very similar and dominated by episodic peaks that matched the Mn increase recorded in surface waters during the 2002 upwelling, while a shell collected during 2003 dry season detect both 2002 and 2003 upwelling events. Larger shells showing an extremely reduced growth display more than 8Mn peaks suggesting at least an 8 years record of seasonal changes in water composition.
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Journal of Great Lakes Research, 2005
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Hydrobiologia, 2010
In keeping with the theme of this volume, the present article commemorates the 50 years of Hutchi... more In keeping with the theme of this volume, the present article commemorates the 50 years of Hutchinson’s (Am Nat 93:145–159, 1959) famous publication on the ‘very general question of animal diversity’, which obviously leads to the more important question regarding the driving forces of biodiversity and their limitation in various habitats. The study of phytoplankton in large lakes is a challenging task which requires the use of a wide variety of techniques to capture the range of spatial and temporal variations. The analysis of marker pigments may provide an adequate tool for phytoplankton surveys in large water bodies, thanks to automated analysis for processing numerous individual samples, and by achieving sufficient taxonomic resolution for ecological studies. Chlorophylls and carotenoids were analysed by HPLC in water column samples of Lake Tanganyika from 2002 through 2006, at two study sites, off Kigoma (north basin) and off Mpulungu (south basin). Using the CHEMTAX software for calculating contributions of the main algal groups to chlorophyll a, variations of phytoplankton composition and biomass were determined. We also investigated selected samples according to standard taxonomic techniques for elucidating the dominant species composition. Most of the phytoplankton biomass was located in the 0–40 m layer, with maxima at 0 or 20 m, and more rarely at 40 m. Deep chlorophyll maxima (DCM) and surface ‘blooms’ were occasionally observed. The phytoplankton assemblage was essentially dominated by chlorophytes and cyanobacteria, with diatoms developing mainly in the dry season. The dominant cyanobacteria were very small unicells (mostly Synechococcus), which were much more abundant in the southern basin, whereas green algae dominated on average at the northern site. A canonical correspondence analysis (CCA) including the main limnological variables, dissolved nutrients and zooplankton abundance was run to explore environment–phytoplankton relations. The CCA points to physical factors, site and season as key determinants of the phytoplankton assemblage, but also indicates a significant role, depending on the studied site, of calanoid copepods and of nauplii stages. Our data suggest that the factors allowing coexistence of several phytoplankton taxa in the pelagic zone of Lake Tanganyika are likely differential vertical distribution in the water column, which allows spatial partitioning of light and nutrients, and temporal variability (occurring at time scales preventing long-term dominance by a single taxon), along with effects of predation by grazers.
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Bookmarks Related papers MentionsView impact
Scientific Data
Climate change and other anthropogenic stressors have led to long-term changes in the thermal str... more Climate change and other anthropogenic stressors have led to long-term changes in the thermal structure, including surface temperatures, deepwater temperatures, and vertical thermal gradients, in many lakes around the world. Though many studies highlight warming of surface water temperatures in lakes worldwide, less is known about long-term trends in full vertical thermal structure and deepwater temperatures, which have been changing less consistently in both direction and magnitude. Here, we present a globally-expansive data set of summertime in-situ vertical temperature profiles from 153 lakes, with one time series beginning as early as 1894. We also compiled lake geographic, morphometric, and water quality variables that can influence vertical thermal structure through a variety of potential mechanisms in these lakes. These long-term time series of vertical temperature profiles and corresponding lake characteristics serve as valuable data to help understand changes and drivers of...
Bookmarks Related papers MentionsView impact
Measurement, Analysis, Simulation, 2003
Bookmarks Related papers MentionsView impact
Hydrobiologia, 1996
Bookmarks Related papers MentionsView impact
Scientific Reports
Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but c... more Globally, lake surface water temperatures have warmed rapidly relative to air temperatures, but changes in deepwater temperatures and vertical thermal structure are still largely unknown. We have compiled the most comprehensive data set to date of long-term (1970–2009) summertime vertical temperature profiles in lakes across the world to examine trends and drivers of whole-lake vertical thermal structure. We found significant increases in surface water temperatures across lakes at an average rate of + 0.37 °C decade−1, comparable to changes reported previously for other lakes, and similarly consistent trends of increasing water column stability (+ 0.08 kg m−3 decade−1). In contrast, however, deepwater temperature trends showed little change on average (+ 0.06 °C decade−1), but had high variability across lakes, with trends in individual lakes ranging from − 0.68 °C decade−1 to + 0.65 °C decade−1. The variability in deepwater temperature trends was not explained by trends in either s...
Bookmarks Related papers MentionsView impact
Aquatic Ecosystem Health & Management
Bookmarks Related papers MentionsView impact
Ecological Indicators
Bookmarks Related papers MentionsView impact
Journal of Hydrometeorology
Accurate precipitation data are fundamental for understanding and mitigating the disastrous effec... more Accurate precipitation data are fundamental for understanding and mitigating the disastrous effects of many natural hazards in mountainous areas. Floods and landslides, in particular, are potentially deadly events that can be mitigated with advanced warning, but accurate forecasts require timely estimation of precipitation, which is problematic in regions such as tropical Africa with limited gauge measurements. Satellite rainfall estimates (SREs) are of great value in such areas, but rigorous validation is required to identify the uncertainties linked to SREs for hazard applications. This paper presents results of an unprecedented record of gauge data in the western branch of the East African Rift, with temporal resolutions ranging from 30 min to 24 h and records from 1998 to 2018. These data were used to validate the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) research version and near-real-time products for 3-hourly, daily, and monthly r...
Bookmarks Related papers MentionsView impact
Journal of Great Lakes Research
Bookmarks Related papers MentionsView impact
ABSTRACT
Bookmarks Related papers MentionsView impact
In this study, I've looked at the zooplankton variability and distribution at night near the ... more In this study, I've looked at the zooplankton variability and distribution at night near the fishing canoes, and tried to correlate these findings to the total fish catch and catch composition. Zooplankton was collected at the surface and from 100 to 0m at two locations: right from the fishermen's boat and about 100m from it. The samples were compared to
Bookmarks Related papers MentionsView impact
Lake Tanganyika harbors a simple pelagic zooplankton community in terms of species abundance. The... more Lake Tanganyika harbors a simple pelagic zooplankton community in terms of species abundance. The micro and meso zooplankton communities consist primarily of one calanoid species, three cyclopoid species, while the macrozooplankton community consist of 15 species of shrimp, one species of medusa and two primary species of fish larvae (Coulter, 1991). The zooplankton community is an important indicator of primary
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
ABSTRACT
Bookmarks Related papers MentionsView impact
Encyclopedia of Earth Sciences Series, 2012
Bookmarks Related papers MentionsView impact
Encyclopedia of Earth Sciences Series, 2012
Bookmarks Related papers MentionsView impact
Biogeosciences, 2007
Bookmarks Related papers MentionsView impact
Biogeosciences Discussions, 2006
Biogenic productivity of Lake Tanganyika is highly dependent on seasonal upwellings of anoxic dee... more Biogenic productivity of Lake Tanganyika is highly dependent on seasonal upwellings of anoxic deep waters. We investigated the shell of freshwater bivalve Pleiodon spekii as a geochemical archive of these periodic hydrological changes tuned by the monsoon regime. The results of a 2-years-long geochemical survey of the coastal waters performed on the dissolved and particulate fractions were put in perspective against laser ablation ICP-MS profiles of Mn in five aragonitic shells from the same lake location. Skeletal Mn profiles in 3 shells are very similar and dominated by episodic peaks that matched the Mn increase recorded in surface waters during the 2002 upwelling, while a shell collected during 2003 dry season detect both 2002 and 2003 upwelling events. Larger shells showing an extremely reduced growth display more than 8Mn peaks suggesting at least an 8 years record of seasonal changes in water composition.
Bookmarks Related papers MentionsView impact
Journal of Great Lakes Research, 2005
Bookmarks Related papers MentionsView impact
Hydrobiologia, 2010
In keeping with the theme of this volume, the present article commemorates the 50 years of Hutchi... more In keeping with the theme of this volume, the present article commemorates the 50 years of Hutchinson’s (Am Nat 93:145–159, 1959) famous publication on the ‘very general question of animal diversity’, which obviously leads to the more important question regarding the driving forces of biodiversity and their limitation in various habitats. The study of phytoplankton in large lakes is a challenging task which requires the use of a wide variety of techniques to capture the range of spatial and temporal variations. The analysis of marker pigments may provide an adequate tool for phytoplankton surveys in large water bodies, thanks to automated analysis for processing numerous individual samples, and by achieving sufficient taxonomic resolution for ecological studies. Chlorophylls and carotenoids were analysed by HPLC in water column samples of Lake Tanganyika from 2002 through 2006, at two study sites, off Kigoma (north basin) and off Mpulungu (south basin). Using the CHEMTAX software for calculating contributions of the main algal groups to chlorophyll a, variations of phytoplankton composition and biomass were determined. We also investigated selected samples according to standard taxonomic techniques for elucidating the dominant species composition. Most of the phytoplankton biomass was located in the 0–40 m layer, with maxima at 0 or 20 m, and more rarely at 40 m. Deep chlorophyll maxima (DCM) and surface ‘blooms’ were occasionally observed. The phytoplankton assemblage was essentially dominated by chlorophytes and cyanobacteria, with diatoms developing mainly in the dry season. The dominant cyanobacteria were very small unicells (mostly Synechococcus), which were much more abundant in the southern basin, whereas green algae dominated on average at the northern site. A canonical correspondence analysis (CCA) including the main limnological variables, dissolved nutrients and zooplankton abundance was run to explore environment–phytoplankton relations. The CCA points to physical factors, site and season as key determinants of the phytoplankton assemblage, but also indicates a significant role, depending on the studied site, of calanoid copepods and of nauplii stages. Our data suggest that the factors allowing coexistence of several phytoplankton taxa in the pelagic zone of Lake Tanganyika are likely differential vertical distribution in the water column, which allows spatial partitioning of light and nutrients, and temporal variability (occurring at time scales preventing long-term dominance by a single taxon), along with effects of predation by grazers.
Bookmarks Related papers MentionsView impact