An inland sea high nitrate‐low chlorophyll (HNLC) region with naturally high pCO₂

Abstract

We present a time series of data for temperature, salinity, nitrate, and carbonate chemistry from September 2011 to July 2013 at the University of Washington's Friday Harbor Laboratories. Samples were collected at the Friday Harbor dock and pump house. Seawater conditions at Friday Harbor were high nitrate-low chlorophyll, with average nitrate and pCO 2 concentrations of 25 6 5 lmol L 21 and 700 6 103 latm (pH 7.80 6 0.06). Transient decreases in surface water nitrate and pCO 2 corresponded with the timing of a spring bloom (April through June). The high nitrate and pCO 2 originate from the high values for these parameters in the source waters to the Salish Sea from the California Undercurrent (CU). These properties are due to natural aerobic respiration in the region where the CU originates, which is the oxygen minimum zone in the eastern tropical North Pacific. Alkalinity varies little so the increase in pCO 2 is due to inputs of dissolved inorganic carbon (DIC). This increase in DIC can come from both natural aerobic respiration within the ocean and input of anthropogenic CO 2 from the atmosphere when the water was last at the sea surface. We calculated that the anthropogenic "ocean acidification" contribution to DIC in the source waters of the CU was 36 lmol L 21 . This contribution ranged from 13% to 22% of the total increase in DIC, depending on which stoichiometry was used for C/O 2 ratio (Redfield vs. Hedges). The remaining increase in DIC was due to natural aerobic respiration.The surface ocean is growing more acidic due to uptake of anthropogenic CO 2 (Brewer 2000;Caldeira and Wickett 2003). As a result, marine ecosystems, the services they provide for humanity, and the societies they support are at risk. Impacts of ocean acidification (OA) will be felt across all ocean basins but are intensified in many coastal areas due to natural processes like upwelling, freshwater input and local respiration (Duarte et al. 2013). Over time, as atmospheric CO 2 continues to increase, the biological consequences of OA can propagate through marine foods webs, from the lowest to the highest levels, including species valued as food resources for humans (Fabry et al. 2008;Hall-Spencer et al. 2008;Portner 2008).In urbanized coastal regions and estuaries there are three sources for acidification of the ocean. One is natural and two are anthropogenic. In all three cases the increases in pCO 2 are due to increases in dissolved inorganic carbon (DIC) rather than decreases in alkalinity. The increase in DIC is calculated from the increasing pCO 2 at constant alkalinity.1. Classic "ocean acidification" is due to the increase in DIC resulting from equilibration of surface seawater with increasing CO 2 in the atmosphere (where it is steadily increasing) (e.g., Feely et al. 2004;Sabine et al. 2004

Oysters and Eelgrass: Potential Partners in a High pCO2 Ocean

“…The pCO 2 levels in the medium and high treatments are higher than the end-of-century projections for the 'rapid economic growth' (IPCC 'A1' scenarios, IPCC 2007IPCC , 2014. For example, pCO 2 averaging 700 (pH = 7.8), but ranging from lower than 400 to higher than 1,000, have been observed in seawater collected weekly between July 2011 and July 2013 from coastal waters within 20 seaway km of our eelgrass collection site and <1 km from other eelgrass beds (Murray et al 2015). For example, pCO 2 averaging 700 (pH = 7.8), but ranging from lower than 400 to higher than 1,000, have been observed in seawater collected weekly between July 2011 and July 2013 from coastal waters within 20 seaway km of our eelgrass collection site and <1 km from other eelgrass beds (Murray et al 2015).…”

“…All replicates were dosed with 33 units/mL Penicillin and 33 ug/mL Streptomycin at the time of the disease challenge in order to prevent bacterial coinfection (e.g., Burge and Friedman 2012). While each phase had different pCO 2 inputs, the ambient treatments in phases I and II are within the range of values currently being recorded in coastal waters in the San Juan Archipelago (Murray et al 2015). All treatments were held at 15°C.…”

Seasonal Changes in Carbonate Saturation State and Air‐Sea CO2 Fluxes During an Annual Cycle in a Stratified‐Temperate Fjord (Reloncaví Fjord, Chilean Patagonia)

“…Reloncaví Fjord, at the study area, was found to be a smaller CO 2 source than fjords in the Northern Hemisphere at higher latitudes, like Roskilde Fjord, North Zealand, Denmark, which has been reported to be an annual CO 2 source (3.9 mol CO 2 ·m −2 ·year −1 ; Mørk et al, ), and Koljo Fjord, Sweden, which also showed a marked transition in p CO 2 dynamics from autumn to spring (Atamanchuk et al, ). In Friday Harbor in the glacially formed San Juan Archipelago (Washington, USA), p CO 2 ranged from ~300 to ~1,100 μatm over a 2‐year period, mostly with high positive Δ p CO 2 , suggesting that the sea is a source for atmospheric CO 2 in this area (Murray et al, ). On the other hand, Kongsfjorden and Tempelfjorden Arctic fjords (Svalbard, Norway) appeared to be less variable systems (in terms of the carbonate dynamics and saturation state of Ω Arag ) and they apparently act as CO 2 sink systems (Fransson et al, , ).…”

Improved marine‐derived POM availability and increased pH related to freshwater influence in an inland sea

“…Water samples were analyzed for alkalinity and dissolved inorganic carbon at the FHL Ocean Acidification Environmental Laboratory (Dickson et al ; Riebesell et al ), and used to calculate pH in CO2calc (ver. 2013; Murray et al ). Error between Durafet pH and calculated sample pH was 0.06 pH units (root mean square error, n = 4), and sensor was 0.04 pH units (RMS error in tris buffer, n = 8), and was considered sufficient to capture dynamics in pH (range 8.07–7.72 in Summer 2013, Spring 2014).…”