Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

This dataset includes nutrients (POC, PON, POP) and chlorophyll concentrations, and cell counts for picoplankton (picoeukaryotes, Synechococcus, bacteria) collected in water samples from the San Pedro Ocean Time-series (SPOT), 2015. They were incubated with six treatments of nitrate and vitamin B.

Water samples were collected from 3 meters depth at the San Pedro Ocean Time-series (SPOT) station (33°33'N, 118°24'W) off the coast of Southern California in March 2015. Six treatments were used: control, nitrate, nitrate+B1, nitrate+B7, nitrate+B12, and nitrate+B1+B7+B12 with triplicate 10L incubations. Growth was tracked daily. Samples were collected initially, and at two points during the experiment: exponential growth and stationary phase. Exponential growth occurred at day 7 and stationary growth varied between treatment ranging from 10-12 days. The incubations were co-limited by nitrate and B12. Samples were flash frozen and stored at -80C until analysis. For further details on the methodology, see Suffridge et al (2017).

Cell counts were made with using flow cytometry. Samples for flow cytometry were collected, fixed with 2% formalin, and frozen at -80C. Analysis for the cellular abundance of heterotrophic bacteria, Synechococcus, and pircoeukaryotes was conducted using a BD Accuri C6 flow cytometer (Becton Dickerson and Company).

Elemental ratios were obtained by measuring particulate organic nutrients: carbon and nitrogen (POC and PON), and particulate organic phosphorus (POP). For particulate organic carbon and nitrogen (POC and PON), 100 ml was filtered onto pre-combusted POC and PON were analyzed on a Costech Elemental Analyzer using methionine and acetanilide as references to calibrate the system at the beginning of the measurements (Fu et al. 2007).

For particulate organic phosphorus (POP) samples, 40 mls were filtered onto precombusted (500°C, 2 h) GF/F filters and rinsed twice with 2 ml 0.17 mol L-1 Na2SO4 solution. The filters were placed in 20 ml borosilicate scintillation vials (pre-combusted at 500°C, overnight) to which was added 2ml 0.017 mol L-1 MgSO4 solution. The vials were then covered with aluminum foil and dried at 95 °C, followed by combustion at 450-500 °C for 2 h. After cooling to room temperature, 5 ml of 0.2 mol L-1 HCl solution was added to each vial, which were then tightly capped and heated at 80°C for thirty minutes to digest POP into inorganic phosphate. The standard molybdate colorimetric method was used to analyze the samples (Solorzano and Sharp 1980). Three GF/F filters were treated in the same way as the samples for blank determinations. POP quantification was done using a Shimadzu UV-1800 UV/Visible Scanning Spectrophotometer.

Chl-a concentrations were measured using the protocol described by Welschmeyer (1994). 40 ml of water samples from each replicate were filtered through GF/F glass fiber filters, 3.0-μm and 8.0-μm polycarbonate membrane for size fractionated Chl-a analyses. After adding 6 ml of 90% acetone, Chl-a was extracted in the freezer at -20°C and measured using the non-acidification method with a Turner Designs 10-AUTM fluorometer after 24 hours.

BCO-DMO Processing:

- added conventional header with dataset name, PI name, version date
- renamed parameters to BCO-DMO standard
- reformatted columns by replacing 'analyte' and 'organism' columns with new columns POC, PON, POP, chla_gff, chla_3um, chla_7_3um, picoeukaryotes, Synechococcus, and bacteria -replacing type, units, and value in order to keep one type of data in each column.
- changed 'syn' to 'Synechococcus', 'PEUK' to 'picoeukaryotes', 'bac' to 'bacteria', CHlA and CHLA to Chla
- changed B1, B7, B12 to N+B1, N+B7, N+B12
- reduced decimal precision
- changed dates from 2011 to 2015

Description from NSF award abstract:
B-vitamins (thiamin (B1), biotin (B7), and cobalamin (B12)) are organic molecules used by all organisms for many biochemical reactions ranging from DNA and amino acid synthesis to carbon dioxide assimilation. Despite their metabolic importance, many marine organisms cannot make them and need to obtain them from the environment. Because the requirement for a specific vitamin is different for different organisms, changes in the species composition of algae could be explained by their different B-vitamin requirements. For example, changes in the biological properties of waters during an algal bloom (removal of needed vitamins and release of other vitamins) may favor algae that require the vitamin released by the previous bloom (setting up a floral succession). This selective preconditioning of the waters may be one factor in the seasonal succession of algal species. However, evaluating the role of vitamins in marine ecology has been difficult. No study to date has been comprehensive enough to estimate the importance of vitamins in primary productivity and species succession. This is especially true in coastal upwelling regions that although relatively small in area, are orders of magnitude more productive than their open-ocean counterparts. In fact, those regions contribute a significant portion of the world fisheries. Therefore, in order to try to predict future changes in the world ocean due to human activity, the variables that influence or control the algal communities that dominate the very productive food chains of upwelling regions need to be identified.

This study will investigate how the availability of B-vitamins affects the dynamics of algal- and bacterioplankton population growth in coastal waters of an upwelling region off Southern California. This comprehensive field investigation will determine in situ temporal concentrations of several dissolved and particulate B-vitamins, inorganic micro- and macronutrients, concurrently with seasonal changes in phytoplankton and bacterial abundances and species composition at a long-term time series station within the San Pedro Basin near Los Angeles. Those measurements will be complemented with field incubation experiments with natural plankton assemblages to study the effect of organic and inorganic nutrient amendments on phytoplankton and bacterial community structure. This study will establish for the first time that the availability of ambient B-vitamins influence algal and bacterial species succession in a highly productive coastal upwelling region and that multiple and differing B-vitamin requirements limit growth of some phytoplankton species in those areas. Furthermore, this study will try to show that coastal upwelling transports some B-vitamins to the phytoplankton community in the photic zone from bacterially-influenced source waters within the upper mesopelagic zone.