Aragonite saturation state and deep-sea coral distribution in the Northwest Hawaiian Islands

• Main Author: Miller, Kelci
• Other Authors: Roark, Brendan
• Format: Thesis
• Language: unknown
• Published: 2017
• Subjects: Emperor Seamount Chain; Ocean acidification
• Online Access: https://hdl.handle.net/1969.1/164450

Seamounts play key roles in the ecology of deep-sea fauna acting as sites of high speciation and hence endemism, oases of biomass and biodiversity. Central to biodiversity are deep-sea corals (DSC), important habitat-forming organisms for invertebrates and fishes, yet the ecology and ecosystem function is not well understood. In addition, DSC and seamount communities are identified as habitats at highest risk from anthropogenic impacts. Fishing activities including trawling and long-lining are pressing anthropogenic threats. In addition to trawling, DSC communities are threatened by ocean acidification where coral species with calcium carbonate skeletons are expected to be severely impacted by reduced pH levels and a shoaling of the aragonite saturation (Ωarag > 1) horizon. In this study we look at the impact of trawling on DSC and potential recovery rates in the Northwestern Hawaiian Islands (NWHI) and the Emperor Seamount Chain (ESC). Our results characterize the water column chemistry (14C, nutrient levels, pH and total alkalinity) at three different sites in order to determine ecosystem health. More specifically we are measuring the total alkalinity through the water column at three areas categorized as previously trawled, currently trawled, and never trawled in the NWHI to define the aragonite saturation horizon and compare it to the current distribution of DSC. These aragonite saturation state measurements are among the first for this remote region including the Papahānaumokuākea Marine National Monument serving as baseline measurements by which to compare to current DSC distribution patterns and help to predict the effect of future climate.