haracterizing the Effects of Two Storms on the Coastal Waters of O‘ahu, Hawai‘i, Using Data from the Pacific Islands Ocean Observing System

Hawaii Coastal Seawater CO2 Network: A Statistical Evaluation of a Decade of Observations on Tropical Coral Reefs

“…The magnitude of instantaneous air-sea CO 2 fluxes (Figure 4) is much greater at the CRIMP-2 buoy than at the South Shore buoys Ala Wai and Kilo Nalu. The larger (positive as well as negative) fluxes observed at the two South Shore sites in January and March 2009 coincided with storm events (see Tomlinson et al, 2011). The annual air-sea CO 2 fluxes at each buoy from June of a given year to May of the next ( Table 2), are typically an order of magnitude larger at CRIMP-2 than at either south shore buoy.…”

“…They differ, however, with respect to riverine input. The Ala Wai site receives direct runoff from the Ala Wai Canal, that usually does not strongly impact the Kilo Nalu buoy (Tomlinson et al, 2011). Consequently, the overall range of pCO 2 sw on diurnal to seasonal time scales (Table 1) is substantially greater at Ala Wai than those observed at Kilo Nalu (Figures 4, 6).…”

“…It is directly affected by tides and winds, and is exposed to open ocean swells from the south, particularly during the Austral winter. The Ala Wai buoy (WQB-AW in Figure 1) is ∼300 m offshore of the mouth of the Ala Wai Canal, where freshwater discharge from a large part of urban Honolulu often delivers high nutrient and sediment loads to the buoy site (e.g., De Carlo et al, 2004;Tomlinson et al, 2011). The Kilo Nalu buoy (WQB-KN in Figure 1), located ∼400 m offshore, is not directly affected by stream discharge, although the local coastal waters receive urban overland runoff, input from nearby storm drains, and groundwater discharge.…”

“…Daily pCO 2 sw fluctuations, however, are much greater at Kilo Nalu's coastal reef ecosystem than in the open ocean. These diurnal variations in pCO 2 sw at Kilo Nalu are mainly driven by greater benthic and water column photosynthesis and respiration, which reflect both the presence of a coral reef at Kilo Nalu, and the effect of discharge of nutrients and suspended solids on biogeochemical processes in proximity to land, with additional effects of calcification and dissolution on the reef (Tomlinson et al, 2011;Drupp et al, 2013). Consequently, the seasonal cycles of pCO 2 sw in both a nearshore reef and the open North Pacific Ocean are similar in amplitude and driven by the temperature effect on CO 2 solubility, while short-term variability is much larger in the coral reef environment largely due to biological processes.…”

“…Highnutrient freshwater entering coastal waters causes increased phytoplankton growth, often leading to the drawdown of pCO 2 sw (Fagan and Mackenzie, 2007;Drupp et al, 2011;Massaro et al, 2012). The duration of such phytoplankton blooms depends strongly on physical processes including water residence time and mixing (e.g., De Carlo et al, 2007;Tomlinson et al, 2011), as well as biotic effects such as predation (e.g., Hoover et al, 2006).…”