Clara Flintrop - Academia.edu (original) (raw)

Papers by Clara Flintrop

Microplastics influence the transport of organic matter from the ocean surface to the deep sea by... more Microplastics influence the transport of organic matter from the ocean surface to the deep sea by altering the settling behavior of marine aggregates. We formed diatom aggregates with differing concentrations of microfibers and observed that microfiber addition stimulated aggregate formation, but decreased structural cohesion and caused them to break apart more readily, resulting in a smaller average size. Microfiber addition also reduced the settling velocity of diatom aggregates in laboratory simulations of particle export using roller tanks. Slower sinking extends aggregate retention time in the upper ocean, thereby increasing the time available for organic matter remineralization in the upper water column. Our laboratory experiments suggest that microfiber concentrations typical of those occurring in the ocean decrease potential export flux by 30-60%. If confirmed in situ, this means that present day microfiber concentrations in surface waters may substantially reduce the effici...

Nature Communications, 2021

Krill and salps are important for carbon flux in the Southern Ocean, but the extent of their cont... more Krill and salps are important for carbon flux in the Southern Ocean, but the extent of their contribution and the consequences of shifts in dominance from krill to salps remain unclear. We present a direct comparison of the contribution of krill and salp faecal pellets (FP) to vertical carbon flux at the Antarctic Peninsula using a combination of sediment traps, FP production, carbon content, microbial degradation, and krill and salp abundances. Salps produce 4-fold more FP carbon than krill, but the FP from both species contribute equally to the carbon flux at 300 m, accounting for 75% of total carbon. Krill FP are exported to 72% to 300 m, while 80% of salp FP are retained in the mixed layer due to fragmentation. Thus, declining krill abundances could lead to decreased carbon flux, indicating that the Antarctic Peninsula could become a less efficient carbon sink for anthropogenic CO2 in future.

Limnology and Oceanography: Methods, 2018

Communications Biology, 2021

Over the past decades, two key grazers in the Southern Ocean (SO), krill and salps, have experien... more Over the past decades, two key grazers in the Southern Ocean (SO), krill and salps, have experienced drastic changes in their distribution and abundance, leading to increasing overlap of their habitats. Both species occupy different ecological niches and long-term shifts in their distributions are expected to have cascading effects on the SO ecosystem. However, studies directly comparing krill and salps are lacking. Here, we provide a direct comparison of the diet and fecal pellet composition of krill and salps using 18S metabarcoding and fatty acid markers. Neither species’ diet reflected the composition of the plankton community, suggesting that in contrast to the accepted paradigm, not only krill but also salps are selective feeders. Moreover, we found that krill and salps had broadly similar diets, potentially enhancing the competition between both species. This could be augmented by salps’ ability to rapidly reproduce in favorable conditions, posing further risks to krill popul...

Limnology and Oceanography: Methods, 2018

Environmental microbiology reports, Aug 21, 2017

Most studies of aquatic plankton focus on either macroscopic or microbial communities, and on eit... more Most studies of aquatic plankton focus on either macroscopic or microbial communities, and on either eukaryotes or prokaryotes. This separation is primarily for methodological reasons, but can overlook potential interactions among groups. We tested whether DNA metabarcoding of unfractionated water samples with universal primers could be used to qualitatively and quantitatively study the temporal dynamics of the total plankton community in a shallow temperate lake. We found significant changes in the relative proportions of normalized sequence reads of eukaryotic and prokaryotic plankton communities over a three-month period in spring. Patterns followed the same trend as plankton estimates measured using traditional microscopic methods. We characterized the bloom of a conditionally rare bacterial taxon belonging to Arcicella, which rapidly came to dominate the whole lake ecosystem and would have remained unnoticed without metabarcoding. Our data demonstrate the potential of universal...

Philosophical Transactions of the Royal Society B: Biological Sciences, 2013

We review the literature and find 16 studies from across Africa's savannas and woodlands wher... more We review the literature and find 16 studies from across Africa's savannas and woodlands where woody encroachment dominates. These small-scale studies are supplemented by an analysis of long-term continent-wide satellite data, specifically the Normalized Difference Vegetation Index (NDVI) time series from the Global Inventory Modeling and Mapping Studies (GIMMS) dataset. Using dry-season data to separate the tree and grass signals, we find 4.0% of non-rainforest woody vegetation in sub-Saharan Africa (excluding West Africa) significantly increased in NDVI from 1982 to 2006, whereas 3.52% decreased. The increases in NDVI were found predominantly to the north of the Congo Basin, with decreases concentrated in the Miombo woodland belt. We hypothesize that areas of increasing dry-season NDVI are undergoing woody encroachment, but the coarse resolution of the study and uncertain relationship between NDVI and woody cover mean that the results should be interpreted with caution; certai...

Microplastics influence the transport of organic matter from the ocean surface to the deep sea by... more Microplastics influence the transport of organic matter from the ocean surface to the deep sea by altering the settling behavior of marine aggregates. We formed diatom aggregates with differing concentrations of microfibers and observed that microfiber addition stimulated aggregate formation, but decreased structural cohesion and caused them to break apart more readily, resulting in a smaller average size. Microfiber addition also reduced the settling velocity of diatom aggregates in laboratory simulations of particle export using roller tanks. Slower sinking extends aggregate retention time in the upper ocean, thereby increasing the time available for organic matter remineralization in the upper water column. Our laboratory experiments suggest that microfiber concentrations typical of those occurring in the ocean decrease potential export flux by 30-60%. If confirmed in situ, this means that present day microfiber concentrations in surface waters may substantially reduce the effici...

Nature Communications, 2021

Krill and salps are important for carbon flux in the Southern Ocean, but the extent of their cont... more Krill and salps are important for carbon flux in the Southern Ocean, but the extent of their contribution and the consequences of shifts in dominance from krill to salps remain unclear. We present a direct comparison of the contribution of krill and salp faecal pellets (FP) to vertical carbon flux at the Antarctic Peninsula using a combination of sediment traps, FP production, carbon content, microbial degradation, and krill and salp abundances. Salps produce 4-fold more FP carbon than krill, but the FP from both species contribute equally to the carbon flux at 300 m, accounting for 75% of total carbon. Krill FP are exported to 72% to 300 m, while 80% of salp FP are retained in the mixed layer due to fragmentation. Thus, declining krill abundances could lead to decreased carbon flux, indicating that the Antarctic Peninsula could become a less efficient carbon sink for anthropogenic CO2 in future.

Limnology and Oceanography: Methods, 2018

Communications Biology, 2021

Over the past decades, two key grazers in the Southern Ocean (SO), krill and salps, have experien... more Over the past decades, two key grazers in the Southern Ocean (SO), krill and salps, have experienced drastic changes in their distribution and abundance, leading to increasing overlap of their habitats. Both species occupy different ecological niches and long-term shifts in their distributions are expected to have cascading effects on the SO ecosystem. However, studies directly comparing krill and salps are lacking. Here, we provide a direct comparison of the diet and fecal pellet composition of krill and salps using 18S metabarcoding and fatty acid markers. Neither species’ diet reflected the composition of the plankton community, suggesting that in contrast to the accepted paradigm, not only krill but also salps are selective feeders. Moreover, we found that krill and salps had broadly similar diets, potentially enhancing the competition between both species. This could be augmented by salps’ ability to rapidly reproduce in favorable conditions, posing further risks to krill popul...

Limnology and Oceanography: Methods, 2018

Environmental microbiology reports, Aug 21, 2017

Most studies of aquatic plankton focus on either macroscopic or microbial communities, and on eit... more Most studies of aquatic plankton focus on either macroscopic or microbial communities, and on either eukaryotes or prokaryotes. This separation is primarily for methodological reasons, but can overlook potential interactions among groups. We tested whether DNA metabarcoding of unfractionated water samples with universal primers could be used to qualitatively and quantitatively study the temporal dynamics of the total plankton community in a shallow temperate lake. We found significant changes in the relative proportions of normalized sequence reads of eukaryotic and prokaryotic plankton communities over a three-month period in spring. Patterns followed the same trend as plankton estimates measured using traditional microscopic methods. We characterized the bloom of a conditionally rare bacterial taxon belonging to Arcicella, which rapidly came to dominate the whole lake ecosystem and would have remained unnoticed without metabarcoding. Our data demonstrate the potential of universal...

Philosophical Transactions of the Royal Society B: Biological Sciences, 2013

We review the literature and find 16 studies from across Africa's savannas and woodlands wher... more We review the literature and find 16 studies from across Africa's savannas and woodlands where woody encroachment dominates. These small-scale studies are supplemented by an analysis of long-term continent-wide satellite data, specifically the Normalized Difference Vegetation Index (NDVI) time series from the Global Inventory Modeling and Mapping Studies (GIMMS) dataset. Using dry-season data to separate the tree and grass signals, we find 4.0% of non-rainforest woody vegetation in sub-Saharan Africa (excluding West Africa) significantly increased in NDVI from 1982 to 2006, whereas 3.52% decreased. The increases in NDVI were found predominantly to the north of the Congo Basin, with decreases concentrated in the Miombo woodland belt. We hypothesize that areas of increasing dry-season NDVI are undergoing woody encroachment, but the coarse resolution of the study and uncertain relationship between NDVI and woody cover mean that the results should be interpreted with caution; certai...