We explore the role of lakes in carbon cycling and global climate, examine the mechanisms influencing carbon pools and transformations in lakes, and discuss how the metabolism of carbon in the inland waters is likely to change in response to climate. Furthermore, we project changes as global climate change in the abundance and spatial distribution of lakes in the biosphere, and we revise the estimate for the global extent of carbon transformation in inland waters. This synthesis demonstrates that the global annual emissions of carbon dioxide from inland waters to the atmosphere are similar in magnitude to the carbon dioxide uptake by the oceans and that the global burial of organic carbon in inland water sediments exceeds organic carbon sequestration on the ocean floor. The role of inland waters in global carbon cycling and climate forcing may be changed by human activities, including construction of impoundments, which accumulate large amounts of carbon in sediments and emit large amounts of methane to the atmosphere. Methane emissions are also expected from lakes on melting permafrost. The synthesis presented here indicates that (1) inland waters constitute a significant component of the global carbon cycle, (2) their contribution to this cycle has significantly changed as a result of human activities, and (3) they will continue to change in response to future climate change causing decreased as well as increased abundance of lakes as well as increases in the number of aquatic impoundments.

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Lakes and reservoirs as regulators of carbon cycling and climate

Communities of microscopic plant life, or phytoplankton, dominate the Earth's aquatic ecosystems. This important new book by Colin Reynolds covers the adaptations, physiology and population dynamics of phytoplankton communities in lakes and rivers and oceans. It provides basic information on composition, morphology and physiology of the main phyletic groups represented in marine and freshwater systems and in addition reviews recent advances in community ecology, developing an appreciation of assembly processes, co-existence and competition, disturbance and diversity. Although focussed on one group of organisms, the book develops many concepts relevant to ecology in the broadest sense, and as such will appeal to graduate students and researchers in ecology, limnology and oceanography.

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The Ecology of Phytoplankton

The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change

Trait-based approaches are increasingly used in ecology. Phytoplankton communities, with a rich history as model systems in community ecology, are ideally suited for applying and further developing these concepts. Here we summarize the essential components of trait-based approaches and review their historical and potential application to illuminating phytoplankton community ecology. Major ecological axes relevant to phytoplankton include light and nutrient acquisition and use, natural enemy interactions, morphological variation, temperature sensitivity, and modes of reproduction. Tradeoffs between these traits play key roles in determining community structure. Freshwater and marine environments may select for a different suite of traits owing to their different physical and chemical properties. We describe mathematical techniques for integrating traits into measures of growth and fitness and predicting how community structure varies along environmental gradients. Finally, we outline challenges and future directions for the application of trait-based approaches to phytoplankton ecology.

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Trait-Based Community Ecology of Phytoplankton

Bioavailable nitrogen is increasing due to human activity, rapidly outpacing increases in another essential nutrient, phosphorous. Penuelas et al. show that this increasing imbalance between these nutrients is likely to significantly affect life and limit carbon storage in this century.

https://hal.archives-ouvertes.fr/hal-01096291/document

Human-induced nitrogen–phosphorus imbalances alter natural and managed ecosystems across the globe

1. The aim of this study was to assess the effects of different nitrogen (N) to phosphorus (P) loading ratios on phytoplankton community composition and primary production in a naturally eutrophic ...

/pdf/effects-of-n-p-loading-ratios-on-phytoplankton-community-2kujykdqle.pdf

Effects of N : P loading ratios on phytoplankton community composition, primary production and N fixation in a eutrophic lake

Recruitment of Microcystis (Cyanophyceae) from lake sediments: the importance of littoral inocula

Recruitment of Microcystis (Cyanophyceae) from lake sediments: The importance of littoral inocula

Lakes play an important role in the cycling of organic matter in the boreal landscape, due to the frequently high extent of bacterial respiration and the efficient burial of organic carbon in sediments. Based on a mass balance approach, we calculated a carbon budget for a small humic Swedish lake in the vicinity of a potential final repository for radioactive waste in Sweden, in order to assess its potential impact on the environmental fate of radionuclides associated with organic matter. We found that the lake is a net heterotrophic ecosystem, subsidized by organic carbon inputs from the catchment and from emergent macrophyte production. The largest sink of organic carbon is respiration by aquatic bacteria and subsequent emission of carbon dioxide to the atmosphere. Although the annual burial of organic carbon in the sediment is a comparatively small sink, it results in the build-up of the largest carbon pool in the lake. Hence, lakes may simultaneously disperse and accumulate organic-associated radionuclides leaking from a final repository.

https://bioone.org/journals/ambio-a-journal-of-the-human-environment/volume-35/issue-8/0044-7447(2006)35[469:ACBOAS]2.0.CO;2/A-Carbon-Budget-of-a-Small-Humic-Lake--An/10.1579/0044-7447(2006)35[469:ACBOAS]2.0.CO;2.pdf

A carbon budget of a small humic lake: an example of the importance of lakes for organic matter cycling in boreal catchments.

Contribution of bacteria in the mucilage of Microcystis spp. (Cyanobacteria) to benthic and pelagic bacterial production in a hypereutrophic lake

During periods of rest, the meroplanktonic cyanobacterium Microcystis accumulates and survives well on shallow littoral bottoms, where environmental conditions may favour an early start of growth and recruitment in spring.

Anna-Kristina Brunberg

Papers

Effects of N : P loading ratios on phytoplankton community composition, primary production and N fixation in a eutrophic lake

Recruitment of Microcystis (Cyanophyceae) from lake sediments: The importance of littoral inocula

A carbon budget of a small humic lake: an example of the importance of lakes for organic matter cycling in boreal catchments.

Contribution of bacteria in the mucilage of Microcystis spp. (Cyanobacteria) to benthic and pelagic bacterial production in a hypereutrophic lake

Benthic overwintering of Microcystis colonies under different environmental conditions