The dataset was collected in wetlands and ponds in eastern Sweden in 2021. Insects were collected at five periods (May, June, July, August and October) in 2021, using floating emergence traps containing soapy water during 72h, and later preserved in 70% ethanol for conservation. Collected insects were counted and identified to genus level, and divided into functional feeding groups. Water nutrient samples were collected when insect traps were set out and at the same sampling point and were kept refrigerated until chemical analyses were performed at the Geochemical Laboratory at the Swedish University of Agricultural Sciences in Uppsala, Sweden. Stoichiometric molar nitrogen:phosphorus ratios were calculated from nutrient concentrations. Greenhouse gas (GHG) data was collected using the headspace method: 30 ml of water from 5 cm depth into a 60 ml syringe, and then 30 ml of ambient air one m above the wetland. the syringe was shaken vigorously for 60 seconds and 15 ml of the headspace gas from the syringe was transferred to a 21 ml Exetainer vial for analysis. Methane and nitrous oxide were then analyzed using a Clarus 500 gas chromatograph with a flame ionisation detector and an electron capture detector. GHG concentrations were converted from ppm to dissolved concentrations using the solubility functions from Wiesenburg and Guinasso (1979) and Weiss and Price (1980), accounting for water temperature and atmospheric pressure at time of sampling, water:air column in the syringe, and ambient air concentration. Chlorophyll-a concentrations were measured as a proxy for aquatic primary production using a FloroSense chlorophyll probe.

Description of the data and file structure

The dataset consists of wetland productivity data and location information, including nitrogen and phosphorus concentrations, water temperature, chlorophyll-a concentrations, stoichiometric N:P ratios, methane- and nitrous oxide concentrations and fluxes, and Chironomidae hatch rates, genus, and functional group across all sampling periods and locations.

The data consists of four tab-spaced text files:

1. nutrient_data_compl.txt
2. nutrient_data_compl_avg.txt
3. chiro_matrix.txt
4. funct_food_pref_mat.txt

nutrient_data_compl.txt contains:

• sample: Sample ID given, used for uniting datasets.
• loc: Designated name of the location.
• chiro: Total abundance of chironomid midges in the sample [n].
• chlor: Measured chlorophyll-a concentration at sample collection point [µg/L].
• ntot: Total measured concentration of nitrogen at sample collection point [µg/L].
• ptot: Total measured concentration of phosphorus at sample collection point [µg/L].
• ch4: Measured concentration of dissolved methane at sample collection point [µg/L].
• n2o: Measured concentration of dissolved nitrous oxide at sample collection point [µg/L].
• np: Ratio between ntot and ptot at sample collection point [N:P ratio].
• wtemp: Water temperature measured at sample collection point [°C].
• n2o_flux: Calculated nitrous oxide flux at sample collection point [µg/m²/h].
• ch4_flux: Calculated methane flux at sample collection point [mg/m²/h].
• month: Month of collection.

nutrient_data_compl_avg.txt contains:

• loc: Designated name of the location.
• tot_chiro: Cumulative abundance of chironomids collected across all months [n].
• h_tax_tot: Shannon-Wiener genus diversity index for all samples and genera across all months except October [H].
• h_food_tot: Shannon-Wiener feeding group diversity index for all samples and genera across all months except October [H].
• avg_chlor: Average measured chlorophyll-a concentration at sample collection point across all months [µg/L].
• avg_ntot: Average measured concentration of nitrogen at sample collection point across all months [µg/L].
• avg_ptot: Average measured concentration of phosphorus at sample collection point across all months [µg/L].
• avg_ch4: Average measured concentration of dissolved methane at sample collection point across all months [µg/L].
• avg_n2o: Average measured concentration of dissolved nitrous oxide at sample collection point across all months [µg/L].
• avg_np: Average ratio between ntot and ptot at sample collection point across all months [N:P ratio].
• avg_n2o_flux: Average calculated nitrous oxide flux at sample collection point across all months [µg/m²/h].
• avg_ch4_flux: Average calculated methane flux at sample collection point across all months [mg/m²/h].

chiro_matrix.txt contains:

• sample: Sample ID given, used for uniting datasets.
• "columns 2 through 44": Abundances of genera of chironomids in the sample [n].

funct_food_pref_mat.txt contains:

• sample: Sample ID given, used for uniting datasets.
• Alg: The abundance of algae eaters chironomid functional group in the sample [n].
• Ani: The abundance of animal eaters chironomid functional group in the sample [n].
• Det: The abundance of detritivorous chironomid functional group in the sample [n].
• Omn: The abundance of omnivorous chironomid functional group in the sample [n].
• Veg: The abundance of vegetation eaters chironomid functional group in the sample [n].

Code/Software

All analyses were run in R (ver. 4.2.1), with libraries and analysis code specified in the accompanying script file.