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325 results on '"Thieltges, David W."'

12. Warming effects on the life cycles of two parasitic copepods with different invasion histories.

Author

Jolma, Elli Rosa Emilia, Born‐Torrijos, Ana, Heesterbeek, Hans, van Leeuwen, Anieke, van Leeuwen, Sonja Maria, Twijnstra, Robert H., Wegner, K. Mathias, and Thieltges, David W.

Subjects
PARASITE life cycles, CALANOIDA, LIFE cycles (Biology), HEAT waves (Meteorology), GLOBAL warming, BODY temperature regulation, COPEPODA
Abstract

Climate change may exacerbate the impact of invasive parasites from warmer climates through pre‐existing temperature adaptations. We investigated temperature impacts on two closely related marine parasitic copepod species that share the blue mussel (Mytilus edulis) as host: Mytilicola orientalis has invaded the system from a warmer climate <20 years ago, whereas its established congener Mytilicola intestinalis has had >90 years to adapt. In laboratory experiments with temperatures 10–26°C, covering current and future temperatures as well as heat waves, the development of both life cycle stages of both species accelerated with increasing temperature. In the parasitic stages, the growth of the established invader increased evenly from 10°C to 22°C, whereas the recent invader barely grew at all at 10°C and grew faster already at 18°C. In contrast, temperature had little effect on the transition success between life cycle stages. However, the highest temperature (26°C) limited the egg development success of the established invader and the host entry success of both species, whereas the infection success of the established invader increased at 18°C and 22°C. In general, our experiments indicate that the main effect of temperature on both species is through development speed and not life cycle stage transition success. Based on regional long‐term temperature data and predictions, the numbers of completed life cycles per year will increase for both parasites. The established invader seems better adapted for low current temperatures (around 10°C), whereas the more recent invader barely develops at these temperatures but can cope in high temperatures (around 26°C). Hence, pre‐existing temperature adaptations of the recent invader may allow the species to better cope with heat waves. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Stable nitrogen isotope analysis of amino acids as a new tool to clarify complex parasite–host interactions within food webs

Author

Riekenberg, Philip M., Joling, Tijs, IJsseldijk, Lonneke L., Waser, Andreas M., van der Meer, Marcel T.J., Thieltges, David W., VPDC pathologie, dPB CR, Leerstoel Aken, VPDC pathologie, dPB CR, and Leerstoel Aken

Subjects
0106 biological sciences, Biomass (ecology), Ecology, Evolution, Stable isotope ratio, Host (biology), 010604 marine biology & hydrobiology, Biology, trophic level, 010603 evolutionary biology, 01 natural sciences, trophic position, Isotopes of nitrogen, Food web, Wadden Sea, Behavior and Systematics, parasite, Ecosystem, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Isotope analysis, Trophic level
Abstract

Traditional bulk isotopic analysis is a pivotal tool for mapping consumer–resource interactions in food webs but has largely failed to adequately describe parasite–host relationships. Thus, parasite–host interactions remain undescribed in food web frameworks despite these relationships increasing linkage density, connectance and ecosystem biomass. Compound-specific stable isotopes from amino acids provides a promising novel approach that may aid in mapping parasite–host relationships in food webs. Here we apply a combination of traditional bulk stable isotope analyses and compound-specific isotopic analysis of nitrogen in amino acids to examine resource use and trophic interactions of five parasites from three hosts from a marine coastal food web (Wadden Sea, European Atlantic). By comparing isotopic compositions of bulk and amino acid nitrogen, we aimed to characterize isotopic fractionation occurring between parasites and their hosts and to clarify parasite trophic positions. Our results indicate that parasitic trophic interactions were more accurately identified using compound-specific stable isotope analysis due to removal of underlying source isotopic variation for both parasites and hosts. The compound-specific method provided clearer trophic discrimination factors in comparison to bulk isotope methods. Amino acid compound specific isotope analysis has widely been applied to examine trophic position within food webs, but our analyses suggest that the method is particularly useful for clarifying the feeding strategies for parasitic species. Baseline isotopic information provided by source amino acids allows clear identification of the fractionation from parasite metabolism by integrating underlying isotopic variations from the host tissues. However, like for bulk isotope analysis, the application of a universal trophic discrimination factor to parasite–host relationships remains inappropriate for compound-specific stable isotope analysis. Despite this limitation, compound-specific stable isotope analysis is and will continue to be a valuable tool to increase our understanding of parasitic interactions in marine food webs.

Published
2021

37. Biological Invasions: Concepts to Understand and Predict a Global Threat

Author

van der Velde, Gerard, Rajagopal, Sanjeevi, Kuyper-Kollenaar, Mirjam, Bij de Vaate, Abraham, Thieltges, David W., MacIsaac, Hugh J., Caldwell, M. M., editor, Heldmaier, G., editor, Jackson, R. B., editor, Lange, O. L., editor, Mooney, H. A., editor, Schulze, E. -D., editor, Sommer, U., editor, Bobbink, Roland, editor, Beltman, Boudewijn, editor, Verhoeven, Jos T. A., editor, and Whigham, Dennis F., editor

Published
2006
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