The sedimentary chironomids and pigments in two Yangtze floodplain (China) lake sediment cores since 1800s CE. The sediment cores were dated using lead-210 with the constant rate of supply (CRS) model. Chironomids were ananlyzed following standard procedures. About 10 g wet samples were firstly deflocculated using 10% potassium hydroxide (KOH) in a 75 °C water bath for about 15 minutes. Then, sediments were gently washed through 212 μm and 90 μm sieves with water after which the residues on the sieves were backwashed into a sorting tray. Chironomid head capsules were picked out individually using fine forceps under a dissecting microscope. The chironomid head capsules were identified using a microscope at ×100/×400 magnification. At least 50 head capsules were picked out from each sample to make the results and interpretations statistically robust.

The sedimentary chironomids and pigments in two Yangtze floodplain (China) lake sediment cores since 1800s CE. The sediment cores were dated using lead-210 with the constant rate of supply (CRS) model. Chironomids were ananlyzed following standard procedures. About 10 g wet samples were firstly deflocculated using 10% potassium hydroxide (KOH) in a 75 °C water bath for about 15 minutes. Then, sediments were gently washed through 212 μm and 90 μm sieves with water after which the residues on the sieves were backwashed into a sorting tray. Chironomid head capsules were picked out individually using fine forceps under a dissecting microscope. The chironomid head capsules were identified using a microscope at ×100/×400 magnification. At least 50 head capsules were picked out from each sample to make the results and interpretations statistically robust.

Relative abundances (%) of diatoms from the top 0,5 cm surface sediment from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada on April 15th, 2019, using a Kajak-Brinkhurst gravity corer. The surface sediment data includes relative diatom abundances (%). Diatom quantifications were done using a light microscope (Zeiss Axio Imager.A2 upright research microscope, University of Helsinki) with phase contrast optics at a x1000 magnification.

Highly branched isoprenoid lipid (HBI) concentrations (ng/ml) from modern water column samples collected from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and May 2019 using a 2,5 L Kemmerer water sampler (pooled sample from 2.5-, 5-, 10-, 15-, 20-, 25- and 30-metre depths).

Relative abundances (%) of diatoms from sediment trap samples from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and July 2019 using an automated Gurney Instruments Baker-style, cylindrical sediment trap (aperture 0.032 m2). The sediment trap was deployed at 40-m depth, 30-m above the seafloor and the rotation for the trap was set to 8-day intervals. Diatom quantifications were done using a light microscope (Zeiss Axio Imager.A2 upright research microscope, University of Helsinki) with phase contrast optics at a x1000 magnification.

Dinoflagellate cyst concentrations (cysts/g) from the top 0,5 cm surface sediment from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada on April 15th, 2019, using a Kajak-Brinkhurst gravity corer. Dinoflagellate cyst quantifications were done using a light microscope (Zeiss Axio Imager.A2 upright research microscope, University of Helsinki) with bright-field optics at a x600 magnification.

Geochemical data (C, N, C/N, δ13C, δ15N) from sediment trap samples from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and July 2019 using an automated Gurney Instruments Baker-style, cylindrical sediment trap (aperture 0.032 m2). The sediment trap was deployed at 40-m depth, 30-m above the seafloor and the rotation for the trap was set to 8-day intervals.

Diatom concentrations (valves/ml) from modern water column samples collected from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and May 2019 using a plankton net (Ø 18 cm, 10 µm, 30-m net haul). Diatom quantification was done using a light microscope (Zeiss Axio Imager.A2 upright research microscope, University of Helsinki) with phase contrast optics at a x1000 magnification.

Highly branched isoprenoid (HBI concentrations (ng/ml) from the bottom 5 cm of modern sea ice samples from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and May 2019 using a Kovacs Mark II core barrel with an internal diameter of 9 cm.

Highly branched isoprenoid lipid (HBI) fluxes (ng/m2/day) from sediment trap samples from the Belcher Islands Archipelago, south-eastern Hudson Bay, Canada between April and July 2019 using an automated Gurney Instruments Baker-style, cylindrical sediment trap (aperture 0.032 m2). The sediment trap was deployed at 40-m depth, 30-m above the seafloor and the rotation for the trap was set to 8-day intervals.