Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
• Data Files
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Notes: In 2015 a 505um mesh was utilized on the multinet however in 2016 and 2017 a 150 um mesh was employed.  The Neocalanus copepods are above the capture efficiency for both nets and no bias is introduced because of the different methodology.

Zooplankton samples were collected from the Gulf of Alaska (Seward Line) in September 2015, 2016 and 2017 using a vertically hauled MultiNet (0.25 m2 MIDI) equipped with a 505um mesh in 2015 and a 150 um mesh in 2016 and 2017. Depth strata sampled were 0-100m, 100-200m, 200-300m, 300-400 and 400-700m.  The samples were immediately preserved in 10% formalin

For analysis each sample was poured into a sorting tray where large organisms, primarily shrimp and jelly fish, were removed. The sample was then sequentially split using a Folsom splitter until a subsample containing approximately 100 specimens of Neocalanus copepods was obtained. The individual organisms were identified to species, staged, and the prosome length was measured using a computer based program interfaced to a digitizing tablet . Dry weights were calculated from literature length- weight equations. Abundance and biomass were calculated for each taxon and tabulated using EXCEL

In EXCEL Abundance and biomass calculations were merged with the ship event logs for date.time, latitude and longitude and formatted for export  (csv).

* Adjusted column names to comply with database requirements
* Biomass columns: value 0 set to NA after discussion with the submitter (no published length weight regression for the larger morph animal type, they did not want to apply a regression that would not accurately predict the biomass of the animal(s)).

NSF abstract:

The Gulf of Alaska supports a diverse and productive marine community that includes many commercially important fishes. Toward the base of this food web are small planktonic crustaceans that serve as the primary food source for many of these fish, as well as seabirds and marine mammals. The copepod Neocalanus flemingeri is one of these crustaceans, and it experiences rapid population growth during each spring's algal, or phytoplankton, bloom. An apparent mismatch between the presence of the youngest stages of the copepod, or nauplii, in early winter and the unpredictable timing of the spring phytoplankton bloom several months later raises important questions about when females reproduce and how this relates to survival and growth of nauplii. Two types of dormancy, diapause in adult females and physiological quiescence in nauplii, may be the key to the success of this copepod species. Timing and duration of the egg-laying period by adult females is linked to emergence from diapause. In addition, nauplii may enter a state of physiological quiescence while food resources are low, resuming growth after phytoplankton levels increase. This research will address a long-standing goal of biological oceanographers to understand dormancy and its role in controlling population cycles in marine copepods. It will use new technologies in molecular biology called transcriptomics to catalog the messages used by the cells to control copepod life processes, in this case those related to dormancy in adults and nauplii. Undergraduate students and a postdoctoral investigator will be trained in interdisciplinary research, and students from Native Hawaiian and Native Alaskan groups will be targeted for participation. Fishing is a major industry in the Gulf of Alaska, and outreach will focus on communicating the role copepods play in marine ecosystems. New content, including images, will be generated for existing websites: the Seward Line long-term observation program, the Alaska Ocean Observing System and the Gulf Watch Alaska Program.

Recruitment to the Neocalanus flemingeri spring population is dependent on successful emergence from diapause followed by reproduction, survival, and growth of the next generation. Individual-based models have made significant progress in predicting population growth in calanoid copepods using food, temperature, and advection as key environmental factors. Few of these models include predictors for naupliar recruitment, however, because little is known about this part of the life cycle given sampling difficulties and the lack of biomarkers to evaluate physiological state. This study will leverage existing monitoring efforts to track the N. flemingeri population during the winter and early spring. The research team will combine laboratory and field approaches to determine duration and synchronization of reproduction in emerging females and strategies for naupliar survival during low food conditions. Zooplankton samples will be processed to enumerate nauplii to species and to determine physiological condition of both nauplii and adult females. Gene expression studies will develop molecular markers for female dormancy and reproductive readiness and for naupliar growth and possible dormancy, which in turn will be used to evaluate field collected individuals. This will be the first comprehensive study to combine molecular and traditional tools to connect diapausing adults, naupliar production, and the resulting spring population of copepodites.