Biology subjects

Kortsch, S.

Publications and source records attributed to Kortsch, S..

4 recordsLinked to original sources

bioRxiv2024

Decline of honeybees and its consequences for beekeepers and crop pollination in western Nepal

O_LIPollination service by insects is globally threatened, yet trends outside of Europe and North America are poorly understood. Therefore, in less-studied regions of the world, beekeeper records can provide valuable insights into changes in pollinator populations. C_LIO_LIWe conducted a questionnaire survey of 116 beekeepers in 10 villages in the Jumla District of western Nepal, where the native honeybee Apis cerana cerana is widely kept as a managed honeybee. We complemented the beekeeper survey with field data on insect-crop visitation, a household income survey, and an interview with a local lead beekeeper. C_LIO_LI76% of beekeepers reported declines in the Apis cerana cerana population. 86% experienced declines in honey yield per hive, and 78% reported declines in the number of beehives per beekeeper. Honey yield per hive fell by 50% between 2012 and 2022, whilst the number of occupied hives decreased by 44%. Beekeepers ranked climate change and declining flower abundance as the most-important drivers of the decline. C_LIO_LIThe drastic bee declines raise concerns for the future food and economic security of this region, where honey sales contribute to 16% of total household farming income. Apis cerana cerana plays a major role in crop pollination and contributes more than 50% of all flower visits to apple, cucumber, and pumpkin. C_LIO_LITo mitigate further declines in this region, we promote the use of pollinator-friendly farming practices including more wild flowers and maintenance of native habitat areas, and well-insulated log or top-bar log hives to buffer bees against extreme temperature fluctuations, which are expected to worsen with climate warming. C_LI

ecology↗

bioRxiv2023

Quantitative description of six fish species' gut contents and abundances of their prey in the benthic food web of the Baltic Sea (1968-1978)

The dataset presents a compilation of stomach contents from six demersal fish species from two functional groups inhabiting the Baltic Sea. It includes detailed information on prey identities, body masses, and biomasses recovered from both the fishs digestive systems and their surrounding environment. Environmental parameters, such as salinity and temperature levels, have been integrated to enrich this dataset. The juxtaposition of information on prey found in stomachs and in the environment provides an opportunity to quantify trophic interactions across different environmental contexts and investigate how fish foraging behaviour adapts to changes in their environment, such as an increase in temperature. The compilation of body mass and taxonomic information for all species allows approaching these new questions using either a taxonomic (based on species identity) or functional trait (based on body mass) approach.

ecology↗

bioRxiv2021

Adaptive foraging behaviour increases vulnerability to climate change

Higher temperatures are expected to reduce species coexistence by increasing energetic demands. However, flexible foraging behaviour could balance this effect by allowing predators to target specific prey species to maximize their energy intake, according to principles of optimal foraging theory. We test these assumptions using a large dataset comprising 2,487 stomach contents from six fish species with different feeding strategies, sampled across environments with varying prey availability over 12 years in Kiel Bay (Baltic Sea). Our results show that foraging shifts from trait-to density-dependent prey selectivity in warmer and more productive environments. This behavioural change leads to lower consumption efficiency at higher temperature as fish select more abundant but less energetically rewarding prey, thereby undermining species persistence and biodiversity. By integrating this behaviour into dynamic food web models, our study reveals that flexible foraging leads to lower species coexistence and biodiversity in communities under global warming.

ecology↗

bioRxiv2019

Food Webs: Insights from a General Ecosystem Model

Food webs have been intensively studied throughout modern ecology, using empirical evidence, statistics and modelling tools to search for consistent patterns, underlying commonalities, and variations between food webs and ecosystems. However, with few exceptions, the modelling approaches have not been based on the emergent properties of complex simulated ecosystems. For the same reason, there have also been few studies of sampling the model, in which different levels of sampling effort are imposed in a controlled simulated environment to explore the effects of varying sampling intensity in order to relate those back to empirical observations. Here, we introduce the Madingley Model, a general ecosystem model based on ecological and biological first principles of interactions between individuals, as a potential tool for analyzing food webs. In doing so, we present the first insights of the analyses of emergent Madingley food web networks. We describe the basic structure of these networks and introduce a process to aggregate and sample the food webs produced by this model so that it can be compared to empirical food web studies. We show that food webs created by this model reasonably reproduce the properties of empirical food web networks. Furthermore, we provide insights about the effects of species aggregation and sampling on the observed structure of empirically documented food webs.

ecology↗