SOW_Pico_1.docx

PERFORMANCE-BASED WORK STATEMENT

I. GENERAL INFORMATION

A. Introduction The U.S. Geological Survey (USGS) California Water Science Center (CAWSC) is requesting bids for epifluorescent microscopic identification and enumeration (tally, density, and biovolume) of picophytoplankton species in surface water samples collected from the Sacramento-San Joaquin Delta and San Francisco Bay (Bay-Delta).

B. Background The CAWSC is conducting multiple studies in the Sacramento-San Joaquin Delta and San Francisco Bay (Bay-Delta).

C. Definitions/Applicable Documents:

Murrel, M.C. & Lores, E.M. (2004) Phytoplankton and zooplankton seasonal dynamics in a subtropical estuary: importance of cyanobacteria. Journal of Plankton Research 26(3): 371–382.

D. Scope.

The U.S. Geological Survey (USGS) California Water Science Center (CAWSC) is requesting bids for epifluorescent microscopic identification and enumeration (tally, density, and biovolume) of picophytoplankton species in surface water samples collected from the Sacramento-San Joaquin Delta and San Francisco Bay (Bay-Delta). Samples will be collected through March 31, 2025. We expect to collect up to 330 samples for analyses during the project period.

Picoplankton samples will be collected with whole-water grab samples collected from near the surface of the water body. Opaque, plastic bottles will be used to minimize exposure to UV light following collection. Samples will be immediately preserved with 37% formaldehyde to a concentration of 0.2%. Samples will sit at ambient temperature for 10-15 minutes in order for cells to take up the preservative. Samples will then be placed on dry ice and remain frozen throughout storage and shipment until they arrive at the processing lab. Comment by Bouma-Gregson, Keith: wet ice or dry ice?

II. WORK REQUIREMENTS

A. Technical Requirements. Comment by Bouma-Gregson, Keith: These requirements are too specific. Is this published in a method somewhere? It would be helpful to cite one of John's publications and say that the contractor is expected to follow that method. Comment by Sturgeon, Crystal L: I got this information from this document on the server: "X:\Discrete Sample Info\discrete_data\BSA\lab_info\Picoplankton Analysis.docx" Comment by Sturgeon, Crystal L: I will look for a publication to cite. Comment by Bouma-Gregson, Keith: Thanks @Sturgeon, Crystal L . I think the current technical requirements look sufficient.

· Contractor will store frozen, preserved samples at -20 °C or colder until ready for filtration.

· Prior to filtration, samples will be thawed in the dark until the entire sample has melted. Samples will then be filtered onto 25 mm, 0.2 µm black polycarbonate (PCTE) membrane filters.

· Filtration will occur in the dark to reduce exposure to UV and fluorescent light. Sample aliquot volumes will be adjusted for sample quality (i.e., samples with heavy sediment load will be settled at lower aliquots to prevent obscuring algal cells).

· Epifluorescent methods will be used with excitation and emission wavelengths for measuring phycocyanin, phycoerythrin, and chlorophyll a.

· An epifluorescence microscope equipped with a Xenon light source and multiple specific excitation/emission filter sets will be used to identify and enumerate picoplankton samples. Samples will be examined at 1000X magnification.

· Both phycoerythrin-rich (PE-rich, orange fluorescence), phycocyanin rich (PC-rich, red fluorescence), and chlorophyll a containing cells will be enumerated and measured for biovolume.

· A minimum of 400 cells will be enumerated for each sample, using a maximum of 100 fields (0.01 mm2 per field).

· If 400 cells cannot be identified in 100 fields, a note will be assigned to the count: “Cannot meet tally in 100 fields”.

· Abundance (cells/L) as well as biovolume (μm3/L) will be calculated (Murrell and Lores 2014). For both PE-rich and PC-rich cells, up to 10 cell width measurements will be taken and an average of those 10 (or fewer) measurements will be used to calculate total biovolume per sample for each cell type.

B. Deliverables.

· An Excel, CSV, or text file that contains the following for each sample:

· Unique sample ID provided by USGS

· Station abbreviation

· Sample date

· Sample time

· Picophytoplankton class (phycoerythrin, phycocyanin, chlorophyll a)

· Tally

· Density (cells/L)

· Total BV (um3/L)

· Lab comments

· Microscopist

· For quality assurance purposes, a split replicate using a second taxonomist to independently identify and enumerate will be done on 5% of samples. Results from both taxonomists will be shared with the USGS.

· For each set of samples, submission of results to USGS is required within 12 weeks of the date on which the samples were received by the Contractor.

· Delivery dates for work/product to be completed and point of delivery. May 31st, 2025. Comment by Bouma-Gregson, Keith: Are we sending only archived samples? Is this enough time for John to enumerate samples collected at the end of the year? Comment by Sturgeon, Crystal L: I will ask John about the timeframe once I have a sample count. Comment by Sturgeon, Crystal L: I extended the POP, John thinks it would be ~January if we get samples into BSA in the next few months.

III. SUPPORTING INFORMATION

A. Place of Performance: Location of Contractor’s facility

B. Period of Performance:

· May 31, 2024 – May 31, 2025

C. Government Furnished Property (GFP): None

D. Special Considerations.

· Recent and long-term experience in the taxonomic identification and enumeration of picophytoplankton species in the Sacramento-San Joaquin Delta and San Francisco Bay (Bay-Delta) required.