Table of Contents

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

Neocalanus flemingeri females were collected in September of 2015, 2016 and 2017 from Knight Island Passage in Prince William Sound, Northern Gulf of Alaska using a Midi MultiNet equipped with a 150 um mesh. Healthy females, taken from samples collected below 400m, were placed individually in 500 ml tissue culture flasks. 

Flasks were filled with seawater from Niskin bottles taken at the same depth as female collection, and sieved through a 35um mesh to remove metazoans.  The flasks were maintained in darkened incubators at a temperature of 5 degrees Celsius. The animals were checked every 2-3 days for the presence of eggs or nauplli.

If production was observed, the female was transferred to a new flask and the eggs and nauplii were sieved from the container and counted under the microscope.  This procedure was continued until all of the females either died or were spawned out (i.e. no ovaries or lipid storage were still present).

For 2015, and 2016 the prosome length of the female was measured after the egg production had ceased. However this length may have not been representative if the females were diseased or dead.  Thus, for 2017 the female was photographed just before she was placed in the flask and the prosome length was measured directly from the scaled image.

Location of Animal Collection per cruise (station KIP2):

TXF15

• Latitude (decimal degrees): 60.275
• Longitude (decimal degrees): -147.987

TXF16

• Latitude (decimal degrees): 60.2752
• Longitude (decimal degrees): -147.989

TXF17

• Latitude (decimal degrees): 60.7313
• Longitude (decimal degrees): -147.987

All egg and nauplii production were compiled into an EXCEL spreadsheet and the final flat-field output was consolidated from the original matrix

Any observations without egg production or nauplii presence were removed. The data from animals that showed disease throughout the experiment were also removed.

BCO-DMO Processing notes:

• No adjustments have been made

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.