DOI: 10.5061/dryad.05qfttf4z
title: Data for: Differential habitat use of a notorious invasive fish, the round goby, in a translocation-relevant system

description: Anthropogenic structures can form novel ecosystem niches. Invasive species
 are often particularly successful in occupying these habitats and utilize
 them as beachheads for further spread. The invasive round goby (Neogobius
 melanostomus, Pallas 1814), an inherently bottom-dwelling fish, uses
 vertical harbour walls as habitat, enabling them to reach boats (i.e.
 potential translocation vectors). To evaluate the relevance of vertical
 habitat use for population dynamics and translocation, we exemplary
 investigated a population of round gobies in a harbour ecosystem.
 Specifically, we investigated differences in trophic niche
 characteristics, individual trophic specialization, phenotypic traits, and
 breeding frequency in wall versus bottom dwelling round gobies.
 Habitat-characteristic dietary signatures indicated habitat partitioning
 during the breeding season. Trophic niches overlapped but were clearly
 distinguishable between the habitats: walls were inhabited by 1.4 times
 more trophic generalists than specialists, while the bottom was inhabited
 by 2.1 times more trophic specialists. Breeding frequency was 24 times
 higher on the walls than on the bottom. After the reproductive season, we
 found a higher similarity in trophic ecology of gobies inhabiting the two
 habitats, and differences in abundance, size, and condition. These results
 are in line with winter migrations to deeper habitats, which are common in
 round gobies in lentic and marine ecosystems. Our results suggest a high
 potential for microgeographic adaptation to either horizontal or vertical
 habitat use in invasive round gobies. We demonstrated that male gobies
 using the walls during the breeding season are larger and heavier,
 suggesting that wall-climbing may select for more competitive individuals.
 Additionally, the overall abundance of round gobies likely increases with
 the additional use of vertical habitat space, which may lead to higher
 propagule pressure. The ability to exploit anthropogenic habitats, and a
 higher translocation probability of competitive individuals, can
 contribute to the invasion success of round gobies in anthropogenically
 influenced aquatic systems.
description: Sample collection: Sampling
 site: commercial harbour Kleinhüningen in Basel, Switzerland
 (47°35'10"N 7°35'27"E) Two
 sampling periods:  19th August - 04th September 2020 (reproductive
 season); and 28th September - 23rd October 2020 (post-reproductive
 season) fishing gear round gobies: baited minnow
 traps baseline organisms: <em>Dickerogammarus
 villosus</em> and <em>Dreissena polymorpha</em>, kept in
 freshwater for &gt; 24 h before processing 
 Sample processing: determination
 of sex, size (total and standard length), wet weight
 extraction of muscle filet (skin- and boneless) and
 liver tissues dried for &gt; 48 h at 60°C and
 grinded to fine powder stable isotope analysis for
 δ<sup>13</sup>C, δ<sup>15</sup>N, C%, and N% using
 an isotope ratio mass spectrometer coupled to an elemental analyser
 (EA-IRMS) for lipid correction of livers: de-fatting
 of eight halves of livers based on a protocol of Bligh and Dyer (1959),
 modified by Turschak et al. (2014) correction using
 mathematical formula based on Post, Layman et al. 2007
description: Isotope data is uploaded in several tables adjusted for the use
 in different parts of the analysis: R script:
 Bussmann_etal_Vertical_habitat_use_R_analyses.R 
 Defatting_Muscles-livers.csv is used in section "Conrol for
 fat content in livers" 
 Bussmann_etal_Vertical_habitat_use_data_NM.csv is used in
 section "Data wrangling", "Individual specialization",
 "paired t-tests for d13C & d15N (muscle/liver)", and
 "Population characteristics". 
 Iso-Data_Muscles_20210305.csv is used in section "Trophic
 niche: size, overlap and position"
 Iso-Data_Muscles_bootstrap_20210830.csv is used in section
 "Isotopic ranges (bootstrapped)"
 Iso_data_NM-and-Baseline_groupingVar2.csv is used in section
 "Niche position" R script:
 Bussmann_etal_Vertical_habitat_use_Figures_for_publication.R
 Iso_data_NM-and-Baseline_groupingVar2.csv is used in
 section "Figure 2:  Bi-plot of δ13C and δ15N with standard
 ellipses" Iso-Data_Ind_20210818.csv is used in
 section "Figure 5: Individual trophic specialization"
 Bussmann_etal_Vertical_habitat_use_data_NM.csv is used in
 section "Figure 4: Trophic position", "Figure 7: Standard
 length", "Figure 7: weight", "Figure 7:
 condition", and "Figure 7: Sex"