Regression modeling of the North East Atlantic Spring Bloom suggests previously unrecognized biological roles for V and Mo

In order to identify the biogeochemical parameters controlling pCO(2), total chlorophyll a, and dimethyl sulfide (DMS) concentrations during the North East Atlantic Spring Bloom (NASB), we used previously unpublished particulate and dissolved elemental concentrations to construct several linear regression models; first by hypothesis testing, and then with exhaustive stepwise linear regression followed by leave-one-out cross-validation. The field data was obtained along a latitudinal transect from the Azores Islands to the North Atlantic, and best-fit models (determined by lowest predictive error) of up to three variables are presented. Total chlorophyll a is predicted best by biomass (POC, PON) parameters and by pigments characteristic of picophytoplankton for the southern section of the sampling transect (from the Azores to the Rockhall-Hatton Plateau) and coccolithophores in the northern portion (from the Rockhall-Hatton Plateau to the Denmark Strait). Both the pCO(2) and DMS models included variables traditionally associated with the development of the NASB such as mixed layer depth and with Fe, Si, and P-deplete conditions (dissolved Fe, dissolved and biogenic silica, dissolved PO43-). However, the regressions for pCO(2) and DMS also include intracellular V and Mo concentrations, respectively. Mo is involved in DMS production as a cofactor in dimethylsulfoxide reductase. No significant biological role for V has yet been determined, although intracellular V is significantly correlated (p-value \u3c 0.05) with biogenic silica (R-2 = 0.72) and total chlorophyll a (R-2 = 0.49) while the same is not true for its biogeochemical analogue Mo, suggesting active uptake of V by phytoplankton. Our statistical analysis suggests these two lesser studied metals may play more important roles in bloom dynamics than previously thought, and highlights a need for studies focused on determining their potential biological requirements and cell quotas

Vanadium speciation and cycling in coastal waters

Different chemical species of dissolved vanadium, V (IV) and V (V), were measured in the water column of the Long Island Sound (LIS). from the East River to the Atlantic boundary during spring and summer conditions. Our preliminary results showed seasonal and spatial changes in total dissolved V and its redox speciation along LIS. Levels of both V species were high in summer (V (IV), 2.2 +/- 1.7 nM; V (V), 22.4 +/- 3.9 nM), and low in spring (V (IV), 1.4 +/- 1.4 nM; V (V), 11.1 +/- 2.6 nM). A V-salinity mixing plot suggests a non-conservative behavior of total dissolved V (and V (IV)) during estuarine mixing. Dissolved V (IV) occurred mostly in western LIS, accounting for 15-25% of the total dissolved V pool in summer hypoxic bottom waters of that region. In spring, V (IV) accounted for up to 40% of the total dissolved V pool in western LIS, likely from sewage inputs. Dissolved V (IV) was also measured near the Quinnipiac, Housatonic and Connecticut rivers (accounting for 10-20% of the total dissolved in summer), suggesting a local source of the reduced V (likely desorption from surficial sediments and resuspended particles). A positive trend between V (IV) and large size phytoplankton biomass suggests that levels of reduced V may be influenced by biological activity. (C) 2009 Elsevier B.V. All rights reserved

Distribution of extracellular flavins in a coastal marine basin and their relationship to redox gradients and microbial community members

The flavins (including flavin mononucleotide (FMN) and riboflavin (RF)) are a class of organic compounds synthesized by organisms to assist in critical redox reactions. While known to be secreted extracellularly by some species in laboratory-based cultures, flavin concentrations are largely unreported in the natural environment. Here, we present pore water and water column profiles of extracellular flavins (FMN and RF) and two degradation products (lumiflavin and lumichrome) from a coastal marine basin in the Southern California Bight alongside ancillary geochemical and 16S rRNA microbial community data. Flavins were detectable at picomolar concentrations in the water column (93–300 pM FMN, 14–40 pM RF) and low nanomolar concentrations in pore waters (250–2070 pM FMN, 11–210 pM RF). Elevated pore water flavin concentrations displayed an increasing trend with sediment depth and were significantly correlated with the total dissolved Fe (negative) and Mn (positive) concentrations. Network analysis revealed a positive relationship between flavins and the relative abundance of Dehalococcoidia and the MSBL9 clade of Planctomycetes, indicating possible secretion by members of these lineages. These results suggest that flavins are a common component of the so-called shared extracellular metabolite pool, especially in anoxic marine sediments where they exist at physiologically relevant concentrations for metal oxide reduction

Microbial cell counts in seawater samples collected on R/V Nerissa and R/V Yellowfin cruises at the San Pedro Ocean Time-series (SPOT) in 2017

Dataset: SPOT Cell CountsThis dataset contains microbial cell counts in seawater samples collected on R/V Nerissa and R/V Yellowfin cruises at the San Pedro Ocean Time-series (SPOT) in 2017. Samples for microbial cell counts were collected at six depths within the euphotic zone using Niskin bottles. Autotrophic picoplankton (Prochlorococcus, Synechococcus, and picoeukaryotes) and heterotrophic prokaryotes were enumerated by flow cytometry. 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/827826NSF Division of Ocean Sciences (NSF OCE) OCE-155927

Halomethane concentrations in cell culture

Dataset: Halomethane concentrations in cell cultureHalomethane concentrations in cell culture 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/712803NSF Division of Ocean Sciences (NSF OCE) OCE-155927

Halomethane concentrations in San Pedro Ocean Time series (SPOT) from March to December 2017

Dataset: Halomethane concentration profileThis dataset contains halomethane concentrations at the San Pedro Ocean Time series from March to December 2017. 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/772335NSF Division of Ocean Sciences (NSF OCE) OCE-155927

Quantification of different chemical forms of cobalamin from San Pedro Ocean Time Series (SPOT) cruises on R/V Nerissa and R/V Yellowfin from March to December 2017

Dataset: SPOT CobalaminsThis dataset contains data on quantifying different chemical forms of cobalamin from San Pedro Ocean Time Series (SPOT) cruises on R/V Nerissa and R/V Yellowfin from March to December 2017. 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/771777NSF Division of Ocean Sciences (NSF OCE) OCE-155927

Beyond the Iron Age: The ecological relevance of bioactive trace metals other than Fe and organic growth factors in aquatic systems

In the last three decades, research has extensively focused on the role of Fe and other mineral nutrients in regulating biological processes, ranging from the surface to the deep ocean. This has produced major breakthroughs in our understanding of the fundamental role of those bioactive elements on the carbon, nitrogen and sulfur cycles and ecosystem function. However, biological processes cannot be entirely sustained by that small set of chemical elements, and new scientific evidence suggests that trace metals other than Fe (e.g., Co, Mo and Ni) as well as essential organic growth factors (e.g., vitamins) may also be crucial in most aquatic systems

INFLUENCE OF INCREASED CARBON DIOXIDE ON PHYTOPLANKTON TRACE METAL QUOTAS IN CULTURES AND FIELD-COLLECTED NATURAL ASSEMBLAGES

participantA significant consequence of future global climate change scenarios on the world's oceans is a rise in the partial pressure of CO2 (pCO2) and associated acidification. This change in carbonate chemistry is likely to affect both the (bio)availability of trace metal ‘micronutrients' to marine phytoplankton and their trace metal requirements. To assess the influence of pCO2 on phytoplankton, we examined trace metal quotas and cell physiology in both culture and field-based incubation experiments using trace metal clean techniques and air:CO2 mixtures including glacial (190 ppm), current (380 ppm), and year 2100 estimates (750 ppm). From various culture experiments with eukaryotic phytoplankton and natural assemblages in field experiments, from the subtropical Pacific (off New Zealand) and the coastal Northeastern Pacific (off southern California), we observed general declines in Fe and Zn quotas with increasing pCO2 – consistent with current trace metal-CO2 availability hypotheses. Interestingly, when co-limited by the essential vitamin B12, a diatom culture experiment showed a positive correlation in Fe, Zn, and Co quotas with pCO2. This highlights the need for experiments that test not only the influence of pCO2 on trace metal quotas, but also the effect of predicted changes in nutrient availability. The use of culture and field approaches for global change experiments both suggest that rising oceanic pCO2 may lead to shifts in phytoplankton trace metal requirements, which in combination with predicted changes in trace metal availability, could have critical impacts on future phytoplankton productivity, dominant phytoplankton taxa, and major nutrient (C, N, and P) oceanic biogeochemistry