Table of Contents

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

This dataset includes growth rates measured as biomass change of the brine shrimp Artemia that were fed a diet supplemented with a variety of phytosterols.

Statistical results of this experiment: Hassett_Sterol_stats2017-12-05.pdf

Phytosterols were synthesized by J. Giner. Rhodomonas cultures were labeled by dissolving sterols in 100% ethanol at a concentration of 2 mg/ml, and then adding the sterol solution at a concentration of 20 µl sterol solution per 100 ml stock culture (at stock density 1x106 cells/liter). The cultures were mixed on a LabGenius orbital shaker for 2 hr at 100 rpm to allow the sterols to bind to the algal surfaces. In vivo chlorophyll a was monitored with a Turner handheld fluorometer to ensure that all food was consumed before the subsequent feeding. This avoided the problem of algal growth diluting the phytosterol concentration over time.

Artemia were hatched in an aerated 2L beaker and the nauplii distributed to 4L beakers containing seawater at 32 ppt. Animals were fed daily with Rhodomonas supplemented with phytosterols at 50,000 cells/ml in 3 replicate, aerated containers for 8 days. In vivo fluorescence was measured with a Turner handheld fluorometer to ensure that the Rhodomonas was consumed between feedings. At the end of the experiment the containers were drained, cleaned of debris, and the number of individuals counted. Samples were then strained on 75µm Nitex and transferred to a preweighed 2.5 cm glass-fiber filter. Filters were dried in a 60 degree C oven overnight and weighed on a Mettler analytical balance. A total of 4 experiments were conducted with Artemia, using 3 replicate treatments of 6 phytosterols, except the last experiment when 5 phytosterols were tested. In the first 3 experiments supplementation was begun 2 days after hatching, while in the fourth experiment supplementation was delayed 2 additional days so that animals began supplementation at a larger size. Results were expressed as both average dry weight per individual and total biomass (mg dry wt) per tank.

BCO-DMO Processing Notes:
- added conventional header with dataset name, PI name, version date
- modified parameter names to conform with BCO-DMO naming conventions
- filled in the empty cells in expt, sterol_id and sterol_name columns with the data from the preceding cell.
- replaced special characters with ascii characters
- replaced spaces with underscores

Description from NSF award abstract:
Autotroph-herbivore interactions in marine food webs are important to fisheries, the global carbon cycle, and, because of harmful algal blooms, human health. The recent hypothesis that harmful algae interfere with the growth and reproduction of zooplankton because of specific structural modifications of the algal sterols will be tested in research on the roles of nutritional factors in planktonic food webs. The effects of marine algal sterols on herbivorous crustaceans will be investigated in three calanoid copepods, Acartia hudsonica, Eurytemora affinis, and Calanus finmarchicus, and brine shrimp, Artemia salina. In this project, studies will be carried out to determine whether marine algal sterols can be metabolized to cholesterol by zooplankton and the relative efficiency of this process. This information is critical for assessing the nutritional value of different algal diets. Using the metabolic studies as a foundation, further experiments will seek to determine whether selected sterols, some of which have structural similarities to steroid hormones, have an inhibitory impact on the growth and reproduction of crustaceans. The analytical techniques used in these experiments will be high-field 13C-nuclear magnetic resonance spectrometry (NMR) and gas chromatography-high resolution mass spectrometry (GC-HRMS). Test sterols for these experiments will be labeled with stable isotopes (13C and 2H) in specific positions by chemical synthesis.