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Flow variation and substrate type affect dislodgement of the freshwater polychaete, Manayunkia speciosa

Freshwater Science

By:
, , ,
DOI: 10.1899/12-140.1

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Abstract

We quantified microscale flow forces and their ability to entrain the freshwater polychaete, Manayunkia speciosa, the intermediate host for 2 myxozoan parasites (Ceratomyxa shasta and Parvicapsula minibicornis) that cause substantial mortalities in salmonid fishes in the Pacific Northwest. In a laboratory flume, we measured the shear stress associated with 2 mean flow velocities and 3 substrates and quantified associated dislodgement of polychaetes, evaluated survivorship of dislodged polychaetes, and observed behavioral responses of the polychaetes in response to increased flow. We used a generalized linear mixed model to estimate the probability of polychaete dislodgement for treatment combinations of velocity (mean flow velocity  =  55 cm/s with a shear velocity  =  3 cm/s, mean flow velocity  =  140 cm/s with a shear velocity  =  5 cm/s) and substrate type (depositional sediments and analogs of rock faces and the filamentous alga, Cladophora). Few polychaetes were dislodged at shear velocities <3 cm/s on any substrate. Above this level of shear, probability of dislodgement was strongly affected by both substrate type and velocity. After accounting for substrate, odds of dislodgement were 8× greater at the higher flow. After accounting for velocity, probability of dislodgement was greatest from fine sediments, intermediate from rock faces, and negligible from Cladophora. Survivorship of dislodged polychaetes was high. Polychaetes exhibited a variety of behaviors for avoiding increases in flow, including extrusion of mucus, burrowing into sediments, and movement to lower-flow microhabitats. Our findings suggest that polychaete populations probably exhibit high resilience to flow-mediated disturbances.

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Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Flow variation and substrate type affect dislodgement of the freshwater polychaete, Manayunkia speciosa
Series title:
Freshwater Science
DOI:
10.1899/12-140.1
Volume
32
Issue:
3
Year Published:
2013
Language:
English
Publisher:
The Society for Freshwater Science
Contributing office(s):
California Cooperative Fish and Wildlife Research Unit
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Freshwater Science
First page:
862
Last page:
873
Number of Pages:
12
Country:
United States
State:
California
Other Geospatial:
Klamath River