20251120 16594600 1.0 TRUE Chlorophyll_a_b_c_Phaeophytin_a This data layer comprises chlorophyll a, b and c and phaeophytin a concentrations from the upper 2 cm of seabed sediments. Bottom sediments were collected using either a Smith McIntyre grab or a Box Core. 0.4 ml samples of surface sediment (0-0.5 cm) were syringed into plastic bags. The samples were wrapped in Al foil and frozen. Chlorophyll concentrations were calculated on sediment extracts (90% acetone + 0.1% MgCO3) at spectrophometric readings at wavelengths of 647, 630, 750 and 664 nm. For chlorophyll-a (Chl-a) and phaeophytin-a, wavelengths of 664 nm and 750 nm (before and after the addition of 200 -L-1 0.1 mol L-1 HCl per 2 mL extractant) and the equation derived by Lorenzen (1967) were used. Chlorophyll b and c concentrations were calculated according to equations provided by Jeffrey and Welschmeyer (2003). The reproducibility of the measurements was +/-10%. Lorenzen, C. J. (1967). Determination of chlorophyll and pheopigments: Spectrophotometric equations. Limnology and Oceanography 12, 343-346. Jeffrey, S.W., and Welschmeyer, N.A. (2003). Spectrophotometric and fluorometric equations in common use in oceanography. In 'Phytoplankton pigments in oceanography: guidelines to modern methods' (Eds. S.W. Jeffrey and R.F.C. Mantoura, and S.W. Wright.) pp. 597-615. (UNESCO Paris.) © Commonwealth of Australia (Geoscience Australia) 2016. This product is released under the Creative Commons Attribution 4.0 International Licence. http://creativecommons.org/licenses/by/4.0/legalcode