Universität zu Köln

Iannino, Alessandra ORCID: 0000-0001-6098-9840, Vosshage, Alexander T. L., Weitere, Markus and Fink, Patrick ORCID: 0000-0002-5927-8977 (2019). High nutrient availability leads to weaker top-down control of stream periphyton: Compensatory feeding in Ancylus fluviatilis. Freshw. Biol., 64 (1). S. 37 - 46. HOBOKEN: WILEY. ISSN 1365-2427

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Abstract

Benthic algal biomass and distribution in freshwater ecosystems are determined by both nutrient availability (bottom-up control) and grazing activity by herbivores (top-down control). Fluctuations in algal nutrient ratios may cause grazers to optimise their food intake through behavioural strategies in order to maintain a constant soft body stoichiometry. Such linkages between nutrient availability and grazing control of algal biomass are as yet poorly understood. In this study, we tested whether the stream-dwelling freshwater gastropod Ancylus fluviatilis would increase its food consumption rate with decreasing periphyton nutrient content, a behaviour known as compensatory feeding. We performed a fully factorial microcosm experiment in which two levels of periphyton phosphorus content (low versus high) were crossed with grazer presence/absence in 12 circular flumes. After 1 week of grazing, food consumption rates were measured by determining the periphyton difference between grazed and ungrazed flumes, and the periphyton biomass variability in every flume was described with a coefficient of variation. The food consumption rate of A. fluviatilis was significantly higher in the low phosphorus compared to the high phosphorus treatment, supporting the compensatory feeding hypothesis. As a result, in the presence of grazers, periphyton biomass was significantly lower under low phosphorus availability, while biomass was not affected by nutrient enrichment in the grazer-free flumes. Despite the strong difference in periphyton phosphorus content, A. fluviatilis soft body stoichiometry did not differ between the two nutrient treatments, suggesting strong stoichiometric homeostasis. Furthermore, the distribution of algal biomass was significantly more heterogeneous in the grazed phosphorus-poor than in the phosphorus-rich periphyton. Our findings suggest that nutrient enrichment may lead to a weaker top-down control of algal biomass in stream ecosystems and to reduced spatial heterogeneity of periphyton abundance.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Iannino, Alessandra UNSPECIFIED orcid.org/0000-0001-6098-9840 UNSPECIFIED Vosshage, Alexander T. L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Weitere, Markus UNSPECIFIED UNSPECIFIED UNSPECIFIED Fink, Patrick UNSPECIFIED orcid.org/0000-0002-5927-8977 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-140739
DOI:	10.1111/fwb.13192
Journal or Publication Title:	Freshw. Biol.
Volume:	64
Number:	1
Page Range:	S. 37 - 46
Date:	2019
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1365-2427
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language BOTTOM-UP CONTROL; FRESH-WATER; ECOLOGICAL STOICHIOMETRY; RESOURCE HETEROGENEITY; PHOSPHORUS LIMITATION; EXCESS CARBON; FOOD QUALITY; BIOMASS; TERRESTRIAL; MARINE Multiple languages Ecology; Marine & Freshwater Biology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14073