Organic Matter Composition, Recycling Susceptibility, and the Effectiveness of the Biological Pump – An Evaluation Using NMR Spectra of Marine Plankton

Carbon (C) sequestration through fertilization of phytoplankton with micronutrients and enhancement of the absorption and retention of atmospheric C by ocean biota heavily depends on the efficiency of the “biological pump”. The long-term effectiveness of this strategy depends on a net transfer of C from the upper ocean-atmosphere system to the deep ocean where the C is removed from contact with the atmosphere for an extended period of time. This C removal can be equated to the amount of C fixation by phytoplankton minus the C cycling and regeneration in the euphotic zone. If the regeneration efficiency is increased, then despite increased C fixation, no net loss (sequestration) of C will result. A reduction in cycling efficiency in the euphotic zone, on the other hand, will increase the effectiveness of the “biological pump” and thus C sequestration. The degree of organic matter biodegradation and recycling depends on the “reactivity” of compounds synthesized by the biota, which in turn, is controlled by the structural characteristic of these compounds. There is considerable evidence that different phytoplankton taxa differ substantially in their biogeochemical characteristics and it is likely that the relative abundance of different compounds synthesized by these distinct taxa, and even within each group at different growth conditions, will differ too. This variability in biosynthesis and thus abundance of a wide range of organic compounds in the water column would lend itself to different susceptibility for biodegradation and regeneration. Knowledge of the distribution of various organic matter structural groups synthesized by distinct taxa, the dependence of the organic matter compound classes on different growth conditions (temperature, light, nutrients) and the selective susceptibility of these compound to regeneration is crucial for estimating the potential for rapid regeneration in the euphotic zone, and thus the effectiveness of the “biological pump”

Quantifying Processes Governing Nutrient Concentrations in a Coastal Aquifer via Principal Component Analysis

Submarine groundwater discharge (SGD) is an important source of nutrients to coastal ecosystems. The flux of nutrients associated with SGD is governed by the volumetric discharge of groundwater and the concentrations of nutrients in groundwater within the coastal aquifer. Nutrient concentrations in the coastal aquifer, in turn, are controlled by processes such as mixing, precipitation, adsorption-desorption, the decay of organic material, and nitrogen-fixation/denitrification. In this study, Principal Component Analysis (PCA) was applied to groundwater and ocean water nutrient concentration data from Monterey Bay, California, to identify and rank processes controlling coastal aquifer nutrient concentrations. Mixing with seawater, denitrification, the decay of organic matter, and desorption of phosphate were determined to be the three most important processes accounting for 39%, 19%, 14%, and 12% of the variability, respectively. This study shows how PCA can be applied to SGD studies to quantify the relative contribution of different processes controlling nutrient concentrations in coastal aquifers

Solution 31P NMR spectra files from sediment samples collected during cruises in the Arctic Ocean, California Margin, and Equatorial Pacific from 1992-1998

Dataset: NMR FID filesSolution 31P nuclear magnetic resonance (NMR) spectra files from sediment samples collected during cruises in the Arctic Ocean, California Margin, and Equatorial Pacific from 1992-1998. The spectra are contained in free induction decay (FID) files. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/794698NSF Division of Ocean Sciences (NSF OCE) OCE-093956

Solution 31P NMR spectra files from sediment samples collected during R/V JOIDES Resolution cruise JRES-336 (IODP336, North Pond) to the western flank of the mid-Atlantic Ridge in November of 2011

Dataset: NMR FID filesSolution 31P nuclear magnetic resonance (NMR) spectra files from sediment samples collected during R/V JOIDES Resolution cruise JRES-336 (IODP336, North Pond) to the western flank of the mid-Atlantic Ridge in November of 2011. Samples were analyzed in 2016. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/816623NSF Division of Ocean Sciences (NSF OCE) OCE-093956

River and Submarine Groundwater Discharge Effects on Diatom Phytoplankton Abundance in the Gulf of Alaska

The Gulf of Alaska is a highly productive ecosystem that supports fisheries and subsistence harvesting of marine resources. The highly productive summer season begins with a bloom that is dominated by diatoms. Both river and submarine groundwater discharge have been recognized as substantial terrestrial nutrient (nitrate and silicate) sources to the Gulf’s coastal waters. Here, the response of in-situ phytoplankton to groundwater and river water additions was evaluated via a bioassay incubation experiment. Special attention was given to diatom genera, as previous studies have shown that submarine groundwater discharge preferentially induces growth of diatoms. The abundance of Pseudo-nitzschia spp., Chaetoceros spp., and Leptocylindrus spp. increased significantly in groundwater and river water containing treatments. Although groundwater and river water are both rich in nitrate and silicate, groundwater treatments with a higher salinity favored a higher relative abundance of Pseudo-nitzschia spp. Conversely, in the highest river water concentration treatments with lower salinity, relative abundances of Pseudo-nitzschia spp. decreased, while Chaetoceros spp. and Leptocylindrus spp. increased. Total abundances of all three genera increased in the lower salinity treatments. These findings could portend changes in the phytoplankton community composition in the Gulf of Alaska as the climate warms and river discharge increases in the coming decades. Furthermore, the findings support previous assertions that submarine groundwater discharge, with higher salinity than river water, is a preferable source of nutrients to the genus Pseudo-nitzschia

Alkaline phosphatase activity in the phytoplankton communities of Monterey Bay and San Francisco Bay

Author Posting. © American Society of Limnology and Oceanography, 2006. This is the author's version of the work. It is posted here by permission of American Society of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 51 (2006): 874–883.Enzyme-labeled fluorescence (ELF) and bulk alkaline phosphatase (AP) activity enzyme assays were used to evaluate the phosphorus (P) status of phytoplankton communities in San Francisco and Monterey bays. Both regions exhibit spatial and temporal variability in bulk AP activity with maximum activities during the early spring and summer periods of high biological productivity. ELF analysis revealed pronounced differences in the makeup of organisms responsible for AP activity in these two environments. In Monterey Bay dinoflagellates are responsible for the bulk of the AP activity. Diatoms infrequently exhibited AP activity. Dinoflagellates that comprised only 14% of all cells counted in Monterey Bay accounted for 78% of AP-producing cells examined. The presence of AP activity in this group suggests that changes in P sources, concentrations, and bioavailability could disproportionably influence this group relative to diatoms in Monterey Bay. In San Francisco Bay, AP production, indicated by ELF, was associated primarily with bacteria attached to suspended particles, potentially used to hydrolyze organic compounds for carbon, rather than to satisfy P requirements. Our results highlight the importance of organic P as a bioavailable nutrient source in marine ecosystems and as a component of the marine P cycle

Reduced calcification and lack of acclimatization by coral colonies growing in areas of persistent natural acidification

Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 110 (2013):11044-11049, doi:10.1073/pnas.1301589110.As the surface ocean equilibrates with rising atmospheric CO2, the pH of surface seawater is decreasing with potentially negative impacts on coral calcification. A critical question is whether corals will be able to adapt or acclimate to these changes in seawater chemistry. We use high precision CT scanning of skeletal cores of Porites astreoides, an important Caribbean reef-building coral, to show that calcification rates decrease significantly along a natural gradient in pH and aragonite saturation (Ωarag). This decrease is accompanied by an increase in skeletal erosion and predation by boring organisms. The degree of sensitivity to reduced Ωarag measured on our field corals is consistent with that exhibited by the same species in laboratory CO2 manipulation experiments. We conclude that the Porites corals at our field site were not able to acclimatize enough to prevent the impacts of local ocean acidification on their skeletal growth and development, despite spending their entire lifespan in low pH, low Ωarag seawater.This research was funded by Na¬tional Science Foundation (NSF) OCE-1040952, a University of California Institute for Mexico and the United States (UC-Mexus) grant (to A.P.), and NSF OCE-1041106 (to A.L.C.). E.D.C. was funded through NSF-GFR and a EPA-STAR fellowships.2013-12-1