Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations

Abstract Migratory animals can have profound impacts on ecosystem structure and function. In streams, salmon are well known for their contrasting influences on primary productivity through nutrient delivery, which enhances potential productivity, and substrate disturbance during nest building, which...

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Main Authors: Evan S. Childress, Peter B. McIntyre
Format: Article
Language:English
Published: Wiley 2016-06-01
Series:Ecosphere
Subjects:
Online Access:https://doi.org/10.1002/ecs2.1301
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spelling doaj-d558ce68c1594c6d922130b9065c72562020-11-25T01:41:21ZengWileyEcosphere2150-89252016-06-0176n/an/a10.1002/ecs2.1301Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrationsEvan S. Childress0Peter B. McIntyre1Center for Limnology University of Wisconsin Madison Wisconsin 53706 USACenter for Limnology University of Wisconsin Madison Wisconsin 53706 USAAbstract Migratory animals can have profound impacts on ecosystem structure and function. In streams, salmon are well known for their contrasting influences on primary productivity through nutrient delivery, which enhances potential productivity, and substrate disturbance during nest building, which reduces algal biomass and primary production. However, most migratory fish species neither disturb the substrate significantly nor die en masse after spawning, hence their influence on ecosystems may differ from that observed in salmon streams. To determine the influence of nutrient subsidies from migrations of iteroparous fish whose broadcast spawning does not disturb the substrate substantially, we compared nutrient limitation, nutrient concentrations, and stream metabolism during spawning migrations of suckers (Catostomus spp.) in Lake Michigan tributaries with and without migration barriers. Although suckers deliver both nitrogen and phosphorus as eggs and waste excretion, only nitrogen concentrations were elevated during the migration (NH4‐N rose 44% relative to sites without a sucker run). Nutrient diffusing substrates demonstrated P‐limitation during the migration at sites spanning a wide range of sucker abundance, suggesting that high demand for likely masked P inputs from fish. Time series analyses indicated that gross primary production (GPP) increased with sucker excretion, but not with egg deposition after accounting for abiotic conditions. In contrast, egg deposition, but not excretion, was associated with a slight increase in ecosystem respiration (ER), suggesting that sucker gametes provide labile carbon that contributes to ER. The effects of suckers contrast with ecosystem responses to salmon migrations, which elevate ER but have mixed effects on GPP. This disparity reflects the fact that suckers fertilize streams without attendant disturbance effects. Our results suggest that basic differences in life history and behavior of migratory fish determine the direction and magnitude of their ecosystem effects. As a result, broad trait‐based predictions of the ecosystem role of migratory fishes may become possible as more species are studied.https://doi.org/10.1002/ecs2.1301Catostomus catostomusCatostomus commersoniimigrationnutrient subsidystream metabolismtrait‐based
collection DOAJ
language English
format Article
sources DOAJ
author Evan S. Childress
Peter B. McIntyre
spellingShingle Evan S. Childress
Peter B. McIntyre
Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
Ecosphere
Catostomus catostomus
Catostomus commersonii
migration
nutrient subsidy
stream metabolism
trait‐based
author_facet Evan S. Childress
Peter B. McIntyre
author_sort Evan S. Childress
title Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
title_short Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
title_full Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
title_fullStr Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
title_full_unstemmed Life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
title_sort life history traits and spawning behavior modulate ecosystem‐level effects of nutrient subsidies from fish migrations
publisher Wiley
series Ecosphere
issn 2150-8925
publishDate 2016-06-01
description Abstract Migratory animals can have profound impacts on ecosystem structure and function. In streams, salmon are well known for their contrasting influences on primary productivity through nutrient delivery, which enhances potential productivity, and substrate disturbance during nest building, which reduces algal biomass and primary production. However, most migratory fish species neither disturb the substrate significantly nor die en masse after spawning, hence their influence on ecosystems may differ from that observed in salmon streams. To determine the influence of nutrient subsidies from migrations of iteroparous fish whose broadcast spawning does not disturb the substrate substantially, we compared nutrient limitation, nutrient concentrations, and stream metabolism during spawning migrations of suckers (Catostomus spp.) in Lake Michigan tributaries with and without migration barriers. Although suckers deliver both nitrogen and phosphorus as eggs and waste excretion, only nitrogen concentrations were elevated during the migration (NH4‐N rose 44% relative to sites without a sucker run). Nutrient diffusing substrates demonstrated P‐limitation during the migration at sites spanning a wide range of sucker abundance, suggesting that high demand for likely masked P inputs from fish. Time series analyses indicated that gross primary production (GPP) increased with sucker excretion, but not with egg deposition after accounting for abiotic conditions. In contrast, egg deposition, but not excretion, was associated with a slight increase in ecosystem respiration (ER), suggesting that sucker gametes provide labile carbon that contributes to ER. The effects of suckers contrast with ecosystem responses to salmon migrations, which elevate ER but have mixed effects on GPP. This disparity reflects the fact that suckers fertilize streams without attendant disturbance effects. Our results suggest that basic differences in life history and behavior of migratory fish determine the direction and magnitude of their ecosystem effects. As a result, broad trait‐based predictions of the ecosystem role of migratory fishes may become possible as more species are studied.
topic Catostomus catostomus
Catostomus commersonii
migration
nutrient subsidy
stream metabolism
trait‐based
url https://doi.org/10.1002/ecs2.1301
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