Space-time variability of carbon standing stocks and fixation rates in the Gulf of Maine, along the GNATS transect between Portland, ME, USA, and Yarmouth, Nova Scotia, Canada

The Gulf of Maine North Atlantic Time Series has been run since 1998 and is the longest transect time series in the Gulf of Maine (GoM), USA. Here we use this coastal time series to document the space-time variability of hydrography, nutrients, phytoplankton standing stocks and carbon fixation in the GoM, in response to several years of extreme river discharge. We hypothesize that, during wet years, fresh water input capped the surface euphotic layer, impeding the upward diffusion of nutrients, thus lowering the phytoplankton biomass and carbon fixation rates. Regional algorithms were derived to estimate particulate organic carbon and carbon fixation. The Howard-Yoder algorithm was implemented to predict integral primary production using satellite ocean color data. Calcification was significantly correlated to primary production, thus allowing regional, satellite-derived calcification estimates. Total GoM and Georges Bank phytoplankton photosynthesis was 38.12 Tg C year(-1) and total calcification was 0.55 Tg C year(-1), yielding an overall ratio of calcification to photosynthesis of 1.44%. Carbon fixation in GoM coastal water (< 60 m bottom depth), GoM deep water (> 60 m) and Georges Bank waters (< 60 m) averaged 33, 56 and 11% of the total primary production of the combined GoM and Georges Bank study area, respectively, and 22, 67 and 11% of the total calcification of the study area, respectively.