Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
  • Problem Description
• Data Files
• Supplemental Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Microzooplankton samples were collected at 3 depths (50, 150, and 280 m) by gently draining 250 mL of seawater from the Niskin bottle with a silicon tube to avoid bubbling. Samples were then preserved with acid Lugol’s solution to a final concentration of 5% (Strom et al., 2019). Glass was added to saturate silica and prevent dissolution of diatoms. Samples were gently mixed and 100 mL subsamples were settled onto microscope slides. Diatoms, dinoflagellates, and ciliates were identified to lowest taxonomic classification, enumerated, and imaged under an inverted microscope. Linear length and widths of cells were measured for a subset of 5 cells (or maximum number) per sample per taxon using ImageJ. Biovolume was estimated using the median linear measurements per taxon and biovolume was calculated using the volumetric equations most closely matching the cell shape (Hillebrand et al., 1999). Biovolume was then converted to carbon biomass according to established diatom and protist carbon:volume relationships (Menden-Deuer and Lessard, 2000).

Day-trips aboard the R/V Nanuq conducted approximately biweekly in Resurrection Bay, AK during January to March, 2023.

For the microscopy, biovolume was estimated using the median linear measurements per taxon and biovolume was calculated using the volumetric equations most closely matching the cell shape (Hillebrand et al., 1999). Biovolume was then converted to carbon biomass according to established diatom and protist carbon:volume relationships (Menden-Deuer and Lessard, 2000).

* Sheet 1 of submitted file "Sheet 1-1-NaupProj2023_Lugols_BCODMO.csv" was imported into the BCO-DMO data system for this dataset.  Table will appear as Data File: 954189_v1_microplankton-microscopy.csv (along with other download format options).

* A unique list of taxonomic names used in the data table was matched with identifiers using the World Register of Marine Species (WoRMS, marinspecies.org) taxa match tool on 2025-02-24. The resulting species list was attached as a supplemental file.
* "Tintinnid" was matched to "Tintinnidae" the formal taxon representation of the name. urn:lsid:marinespecies.org:taxname:183533
* The incorrect phonetic spelling of "Dytilum" was corrected to "Ditylum" (urn:lsid:marinespecies.org:taxname:149022) in the data table and subsequent supplemental file.
* "Navicula" and "Nitzschia" returned ambiguous name match results however, each only had one matching result that was a diatom as described by the column "group" to the appropriate LSIDs could be assigned in this dataset. The other possible matches were in Mollusca and Platyhelminthes.

NSF Award Abstract
Global climate change and associated extreme weather events are increasingly impacting marine communities at all trophic levels and leading to shifts in the timing of life history events. This project is investigating the annual restart of the spring zooplankton community in the Gulf of Alaska in order to determine the timing of species-specific recruitment and growth. Zooplankton are small pelagic animals that are a critical link between microalgae and protozoans and higher levels in the food web including economically important fishes, birds and marine mammals. While their abundances and species composition have been documented over part of the annual cycle between late spring and fall, this project focuses on winter and early spring. The project integrates traditional methods with modern molecular approaches to characterize the diversity, development, feeding and physiology of zooplankton, especially the early developmental stages of copepods (small crustaceans). The goal is to determine which species are there, how many are present and where they are in the water column, and to reveal indicators of their health. Broader impacts include research training for three graduate students and at least four undergraduates in biological oceanography and physiological ecology. Outreach activities are focusing on broadening the public’s understanding of plankton ecology. An illustrated zooplankton guide for the Gulf of Alaska and plankton module for school teachers and students is being produced in collaboration with the Center for Alaskan Coastal Studies. Other plans include sponsorship of nature-drawing workshops on zooplankton and the production of an Art & Science traveling exhibit.

This project is tracking zooplankton population abundances, species composition and developmental stages through the spring restart in a high-latitude fjord in the northern Gulf of Alaska. While the entire zooplankton community is being characterized, the main focus is on the difficult-to-assess early developmental stages of copepods, which dominate the late spring biomass in the region. Three central hypotheses guide the research: 1) high abundances of copepod nauplii are present before any measurable increases in food in surface waters; 2) species diversity increases between winter and spring, with nauplii from large lipid-rich capital-breeding species appearing first, followed by those from income- and hybrid-strategy species and finally nauplii that emerge from dormant eggs; 3) prior to the appearance of food resources, nauplii from capital-breeding species conserve resources by delaying development and entering a state of dormancy in the second and third naupliar stages. The project entails intensive depth-stratified field sampling to characterize the wild community, in combination with laboratory experiments on nauplii to determine their responsiveness to food. The prey are being characterized by measuring chlorophyll a, dietary and prey community DNA sequencing and flow cytometry to establish diversity and abundances. Size-fractionated zooplankton samples are being analyzed using microscopy and community DNA sequencing to ascertain species diversity, developmental stage distribution and abundances. Feeding activity is being measured using dietary DNA sequencing of nauplii followed by comparisons with the prey field. Dormancy in nauplii is being determined by differential gene expression of target genes (RT-qPCR) and high-throughput sequencing of mRNA of individuals (transcriptomics) and community samples (meta-transcriptomics). Short-term and long-term effects of food availability on dormancy, development and growth are being quantified in laboratory experiments. Broader impacts are focused on training of students in interdisciplinary research and state-of-art techniques, and public outreach to introduce plankton ecology to broader audiences.