Population recovery and occurrence of the endemic Rhine sculpin (Cottus rhenanus)

The Rhine sculpin (Cottus rhenanus) is a benthic rheophilic fish species that is endemic to tributaries of the rivers Rhine and Meuse in North-western Europe. Little is known about its occurrence and individuals density in relation to habitat characteristics. A core population of C. rhenanus occurs in the River Geul in the Netherlands. Since the late 19th century, this river was heavily polluted by communal and industrial wastewater, causing a strong population decline. As the core population of C. rhenanus is recovering, the status, distribution, and habitat use could be studied to facilitate recovery in other locations. Cottus rhenanus density of individuals significantly increased over the period 2005-2015 and it became one of the most abundant fish species in assemblages. Negative relationships were observed between C. rhenanus densities and a high abundance of boulders (>200 mm), large structures such as woody debris, and water depth. The population increase and recolonization of C. rhenanus coincided with water quality improvement, which suggests that this fish species can be used to assess small streams ecosystem integrity. The recent range expansion of the Ponto-Caspian round goby (Neogobius melanostomus) poses a high risk of negative effects on C. rhenanus populations via food and shelter competition. Further water quality improvement, habitat conservation, and prevention of the spread of invasive gobies could favour C. rhenanus populations within their natural range

Data from: Population recovery and occurrence of the endemic Rhine sculpin (Cottus rhenanus)

Two datasets belonging to the paper "Population recovery and occurrence of the endemic Rhine sculpin (Cottus rhenanus)" published in Knowledge and Management of Aquatic Ecosystems, are provided here. Since little was known about the occurrence, densities and habitat use of C. rhenanus, this study was conducted. The study area was located in the River Geul and tributaries, in the south of the Netherlands. The first dataset "WFD 2005-2010-2015 fish data.csv" contains data of fish in transects sampled as part of ecological status assessments of water systems according to the EU Water Framework Directive. Average 300-metre transects in upstream direction in one run using handheld backpack electrofishing equipment. The second dataset "Habitat characterization Cottus rhenanus 2014.csv" contains data of the Rhine sculpin (and other encountered fish species) in relation to its habitat. The data were collected in the same way as described above. In addition, we estimated the relative abundance of each sediment type (bed substratum) per transect, which yielded the ordinal categories: 0%, 200 mm). Furthermore, we estimated the percentage area of large structures (e.g., woody debris) and riffles. Finally, we measured stream width (m) and depth (cm). This was done by recording width with a tape measure and depth with a measuring rod at five (beginning, middle, end and two representatives in between) locations in a transect. The mean values were recorded as stream width and depth. The included coordinates refer to the start and end of a transect. The coordinate system used here concerns Amersfoort RD (EPSG: 28992). Abstract The Rhine sculpin (Cottus rhenanus) is a benthic rheophilic fish species that is endemic to tributaries of the rivers Rhine and Meuse in North-western Europe. Little is known about its occurrence and individuals density in relation to habitat characteristics. A core population of C. rhenanus occurs in the River Geul in the Netherlands. Since the late 19th century, this river was heavily polluted by communal and industrial wastewater, causing a strong population decline. As the core population of C. rhenanus is recovering, the status, distribution, and habitat use should be studied to facilitate recovery in other locations. Cottus rhenanus density of individuals significantly increased over the period 2005-2015 and it became one of the most abundant fish species in assemblages. Negative relationships were observed between C. rhenanus densities and a high abundance of boulders (> 200 mm), large structures such as woody debris, and water depth. The population increase and recolonization of C. rhenanus coincided with water quality improvement, which suggests that this fish species can be used to assess small streams ecosystem integrity. The recent range expansion of the Ponto-Caspian round goby (Neogobius melanostomus) poses a high risk of negative effects on C. rhenanus populations via food and shelter competition. Further water quality improvement, habitat conservation, and prevention of the spread of invasive gobies could favour C. rhenanus populations within their natural range

Determining the Accuracy and Reliability of Indirect Calorimeters Utilizing the Methanol Combustion Technique

Background: Several indirect calorimetry (IC) instruments are commercially available, but comparative validity and reliability data are lacking. Existing data are limited by inconsistencies in protocols, subject characteristics, or single-instrument validation comparisons. The aim of this study was to compare accuracy and reliability of metabolic carts using methanol combustion as the cross-laboratory criterion. Methods: Eight 20-minute methanol burn trials were completed on 12 metabolic carts. Respiratory exchange ratio (RER) and percent O2 and CO2 recovery were calculated. Results: For accuracy, 1 Omnical, Cosmed Quark CPET (Cosmed), and both Parvos (Parvo Medics trueOne 2400) measured all 3 variables within 2% of the true value; both DeltaTracs and the Vmax Encore System (Vmax) showed similar accuracy in measuring 1 or 2, but not all, variables. For reliability, 8 instruments were shown to be reliable, with the 2 Omnicals ranking best (coefficient of variation [CV] < 1.26%). Both Cosmeds, Parvos, DeltaTracs, 1 Jaeger Oxycon Pro (Oxycon), Max-II Metabolic Systems (Max-II), and Vmax were reliable for at least 1 variable (CV ≤ 3%). For multiple regression, humidity and amount of combusted methanol were significant predictors of RER (R2 = 0.33, P <.001). Temperature and amount of burned methanol were significant predictors of O2 recovery (R2 = 0.18, P <.001); only humidity was a predictor for CO2 recovery (R2 = 0.15, P <.001). Conclusions: Omnical, Parvo, Cosmed, and DeltaTrac had greater accuracy and reliability. The small number of instruments tested and expected differences in gas calibration variability limits the generalizability of conclusions. Finally, humidity and temperature could be modified in the laboratory to optimize IC conditions