Universität zu Köln

Ahlers, Johanna ORCID: 0009-0009-6545-9668 and von Elert, Eric ORCID: 0000-0001-7758-716X (2025). Signals in Flux: Investigating the Seasonal Turnover of the Diel Vertical Migration‐Inducing Kairomone 5α‐Cyprinol Sulfate. Freshwater Biology, 70 (10). pp. 1-11. Wiley. ISSN 0046-5070

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Abstract

1. 5α- Cyprinol sulfate (CPS), a kairomone released by cyprinid fishes, induces diel vertical migration (DVM) in Daphnia and thus shapes ecosystem dynamics wherever both taxa co-occur. Here, we provide the first in situ quantification of CPS turno- ver, revealing strong temporal variability in this chemical signal and its ecosystem-wide consequences in fluctuating freshwa- ter environments. Our aim was to test whether CPS dynamics are governed by rapid turnover rather than serving as a stable proxy for predator abundance. 2. Using an integrated approach combining laboratory feeding trials, field sampling and predictive modelling, we present a temperature-dependent framework that captures the interplay between CPS exudation and degradation. 3. We showed that CPS exudation is tightly linked to fish feeding intensity, independent of fish size, while microbial degrada- tion emerged as the dominant removal process, with degradation rates reaching up to 85.7% per day in lake water. Seasonal field data from a mesotrophic lake revealed that CPS concentrations range from 40 to 900 ng/L over a season, peaking in late summer, potentially indicating increased fish feeding and shifts in prey availability. 4. Our findings highlight the need to fundamentally reconsider CPS as an environmental cue: rather than reflecting predator abundance, CPS concentrations primarily reflected predator feeding activity, dynamically modulating the strength of DVM and its cascading effects on freshwater food webs. This extends the relevance of CPS beyond our study lake, informing models of DVM and trophic interactions in cyprinid-rich waters globally.

Item Type:	Article
Creators:	Creators Email ORCID ORCID Put Code Ahlers, Johanna UNSPECIFIED https://orcid.org/0009-0009-6545-9668 UNSPECIFIED von Elert, Eric UNSPECIFIED https://orcid.org/0000-0001-7758-716X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-805084
Identification Number:	10.1111/fwb.70109
Journal or Publication Title:	Freshwater Biology
Volume:	70
Number:	10
Page Range:	pp. 1-11
Number of Pages:	11
Date:	14 October 2025
Publisher:	Wiley
ISSN:	0046-5070
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Zoologisches Institut
Subjects:	Life sciences
Uncontrolled Keywords:	Keywords Language chemical ecology ; Daphnia ; DVM ; kairomones ; microbial degradation English
['eprint_fieldname_oa_funders' not defined]:	Publikationsfonds UzK
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80508