Land use and nitrogen loading in seven estuaries along the southern Gulf of St. Lawrence, Canada

Nitrous oxide emissions could reduce the blue carbon value of marshes on eutrophic estuaries

“…The GWPs of N 2 O Table 1. Characteristics of study sites on Prince Edward Island and in New Brunswick, Canada from Bugden et al (2014), McIver et al (2015, PEI Department of Agriculture and Forestry (2003) and Hauck et al (2009 and CH 4 reflect the forcing of gases when emitted as a pulse, but their sustained fluxes from ecosystems have even greater climate feedbacks (Neubauer and Megonigal 2015) which we recognize as we compare our measured greenhouse gas fluxes from marshes to their capacity to serve as CO 2 sinks. In addition to its contribution to climate warming, N 2 O is expected to remain the primary substance responsible for stratospheric ozone depletion throughout the 21st century (Ravishankara et al 2009).…”

A human impact metric for coastal ecosystems with application to seagrass beds in Atlantic Canada

“…• Nutrients from point-and non-point sources and resulting eutrophication is a major driver of seagrass declines (Hauxwell et al 2003, Orth et al 2006). • N loading rate represents intensity of nutrient pollution (McIver et al 2015), delta-N accounts for dilution from freshwater inflow and tidal exchange (Bugden et al 2014).…”

“…Nutrient pollution: Nutrient pollution was divided into two sub-measures: nitrogen loading rate and delta-N (DN). We used data from previous applications of a nitrogen loading model (NLM), originally developed for Waquoit Bay, Massachusetts (Valiela et al 1997), for several bays in Atlantic Canada, including 7 bays in NB (McIver et al 2015), 21 bays in NS (Nagel et al 2018), and 6 bays in PEI (Palmer 2018). For the remaining 19 bays, we estimated total nitrogen load (kg N yr -1 ) using linear regression models specific to each province (Supplementary Methods, Fig.…”

“…S1 and S2). Briefly, the NLM estimates watershed and atmospheric derived total dissolved nitrogen loads from several point (i.e., direct atmospheric deposition, wastewater discharge, seafood processing plants, finfish aquaculture) and non-point sources (i.e., indirect atmospheric deposition, septic systems, and fertilizer addition) with appropriate loss parameters (Valiela et al 1997, McIver et al 2015, McIver et al 2018. Final nitrogen loading rates were calculated by summing across all sources and standardized to the area of each bay (kg N ha bay -1 yr -1 ) to account for dilution effects.…”

Effects of Bridge Construction and Wastewater Effluent on Phytoplankton Abundance and Sediment Geochemistry in an Atlantic Temperate Coastal Bay Since 1930

“…However, despite the well documented effects of bridges and 23 causeways on water flow, relatively little is known of their impacts on aquatic 1 ecosystems, particularly in comparison to full closure of flow by dams (Rosenberg et Here we perform the first quantitative test of the effects of embayment closure by 12 a bridge in production and biogeochemical features of a coastal straight environment. 13 Specifically, we compared fossil profiles of pigments from phytoplankton and stable 14 isotopes of C and N in sediment cores retrieved on either side of a 776-m long bridge 15 built in 1957-1959 that connects a 150-km 2 island to the mainland in Atlantic Canada. 16 We expected that sedimentation rates, fossil pigments, organic matter content, C:N ratio, 17  13 C and  15 N should follow similar decadal patterns at the two coring sites until bridge 18 construction.…”