Modelling patterns of coexistence of three congeneric headwater fishes

Abstract

Abstract1. Mechanisms driving patterns of occurrence and co-occurrence among NorthAmerican freshwater fishes are poorly understood. In particular, the influence ofbiotic interactions on coexistence among stream reaches and their effects on regionalspecies distribution patterns is not well understood for congeneric headwaterfishes.2. Occupancy models provide a useful framework for examining patterns of co-occurrencewhile also accounting for imperfect detection. Occupancy models maybe extended to test for evidence that a dominant species influences the occurrenceof a subordinate species and thus evaluate support for the hypothesis thatspecies interactions drive patterns of coexistence.3. We examined patterns of occurrence and co-occurrence at the stream-reach scaleamong three species of darters (Percidae: Etheostomatinae) that occupy headwaterstreams within a Gulf Coastal Plain drainage in the south-eastern U.S.A. Weassessed species occurrences at 97 sites in first- to third-order streams on oneoccasion each and used data from four sub-reaches sampled with equal effort ateach site to estimate species-specific detection probabilities. Following sampling,a suite of habitat variables was collected at three equidistant points along eachof the three transects established within a sub-reach. Coarse (stream-segment,catchment, network) scale variables were also incorporated using geospatial data.Single-species and two-species occupancy models were used to examine patternsof occupancy and coexistence.4. The occupancy of each species was influenced by distinct habitat variables.Goldstripe darters (Etheostoma parvipinne) were constrained by a stream size gradient,groundwater input appeared to influence the occurrence of Yazoo darters(Etheostoma raneyi), and local habitat heterogeneity (e.g. variation in depthand current velocity) appeared to influence the occupancy of redspot darters(Etheostoma artesiae).5. We found no evidence that the presence of one species influenced the occurrenceof another within a stream-reach based on two-species occupancy models.Rather, species co-occurrences were best explained as independent occurrenceswithin a stream-reach according to species-specific habitat associations.

Citation

Hubble, Joshua P.; Schaefer, Jacob F.; Warren Jr., Melvin L.;Sterling, Kenneth A. 2020. Modelling patterns of coexistence of three congeneric headwater fishes. Freshwater Biology. 2020;65:2017-2027. DOI: 10.1111/fwb.13486