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Your search keyword '"Koizumi, Shuntaro"' showing total 2 results
Start Over Author "Koizumi, Shuntaro" Topic zooplankton
2 results on '"Koizumi, Shuntaro"'

1. Klimatförändringseffekter på akvatiska konsumentsamhällen

Author

Koizumi, Shuntaro

Subjects
browning, zooplankton, fish, Ekologi, Climate Research, warming, Ecology, aquatic consumers, ecosystem experiment, Climate change, benthic insects, Klimatforskning
Abstract

Climate change represents a serious threat to aquatic ecosystems, with an increase in lake temperatures already observed that is expected to continue in the near future. Aside from the direct effects of warming, climate change is also partially responsible for the browning of lakes. Browning is an ongoing phenomenon related to the increased export of terrestrial dissolved organic matter into lakes. With ongoing climate changes, lakes are becoming warmer and browner. This has major impacts on the food web dynamics of these systems. Many studies have previously examined the effects of warming and browning on consumer responses, mainly through spatial surveys. However, a mechanistic understanding of how consumers in the food web will respond to simultaneously occurring warming and browning remains poorly understood. Using two large-scale ecosystem experiments, I studied the effects of warming and browning on consumer growth, size-structure, and population responses, and the potential mechanisms that dictate the emergent responses. In general, warming led to reduced consumer biomass and size structure, whilst browning led to an increase. Specifically, warming reduced intermediate consumer biomass and fish top consumer abundance, biomass and size structure, while browning either led to little to no changes in intermediate consumers, but increased fish top consumer abundance, biomass, and production. However, these responses were determined by food-web structure, interactions, and context-dependent mechanisms. This thesis advances our understanding of the mechanisms that drive changes in consumer responses to warming and browning and provides a better understanding of how ongoing climate may affect the structure and functioning of freshwater ecosystems.

Published
2023

2. Experimental warming and browning influence autumnal pelagic and benthic invertebrate biomass and community structure.

Author

Koizumi, Shuntaro, Hamdan, Mohammed, Puts, Isolde Callisto, Bergström, Ann‐Kristin, Karlsson, Jan, and Byström, Pär

Subjects
*INVERTEBRATE communities, *DISSOLVED organic matter, *CONSUMER behavior, *AUTUMN, *SPRING, *YOUNG consumers
Abstract

Globally, lakes are warming and browning with ongoing climate change. These changes significantly impact a lake's biogeochemical properties and all organisms, including invertebrate consumers. The effects of these changes are essential to understand, especially during critical periods after and before the growing season, that is, autumn and spring, which can determine the composition of the invertebrate consumer community.In this study, we used a large‐scale experimental pond system to test the combined effect of warming (+3°C) and increased input of terrestrial and coloured dissolved organic carbon (gradient of 1.6–8.8 mg/L in the ambient and 1.6–9.3 mg/L in the warm)—which causes browning—on zooplankton and benthic macroinvertebrate biomass and composition during the autumn and the following spring.Total zooplankton biomass decreased with warming and increased with browning, while total zoobenthos did not respond to either treatment. Warming and browning throughout the autumn had no overall interactive effects on zooplankton or zoobenthos. Autumnal warming decreased total pelagic consumer biomass, caused by a decrease in both Rotifera and Copepoda. In contrast, there was no effect on overall benthic consumer biomass, with only Asellus sp. biomass showing a negative response to warming. An autumnal increase in dissolved organic carbon led to increased total pelagic consumer biomass, which was related to increases in Daphnia sp. biomass but did not affect zoobenthos biomass. While we expected zooplankton and zoobenthos biomass to follow responses in primary and bacterial production to treatments, we did not find any relationship between consumer groups and these estimates of resource production.Our results suggest that consumer responses to warming and browning during autumn may lead to less overarching general changes in consumer biomass, and responses are mostly taxon‐specific.This study gives novel insights into the effects of warming and browning on consumer biomass during autumn and spring and increases the understanding of the effects of climate change on invertebrate community biomass in the different habitats. [ABSTRACT FROM AUTHOR]

Published
2023
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