WWW.WA S .ORG • WORLD AQUACULTURE • SEP TEMBER 2022 51 Evaluating kelp growth in Alaska. were conducted over two consecutive kelp farming seasons (2019-2020 and 2020-2021) at six sugar kelp Saccharina latissima farms – five in New England and one in South Central Alaska – from which 720 tissue samples from 240 blades were collected and processed. The illustrated protocol was amended throughout the process until data supported sampling either the basal or middle sections of the blade with reproducible results (Fig. 4). The University of Alaska Fairbanks holds the copyrights for the NET. To our knowledge, this toolkit is the first of its kind developed for kelp mariculture and specifically assembled to build community capacity in the determination of nutrient removal through kelp farming. Our partnership with kelp farmers will effectively assist in establishing regional and interannual comparisons showing the extent of variability in carbon and nitrogen removal by kelp farms across large geographic regions. We foresee that the NET will assist in providing baseline information to calculate potential earnings by kelp farmers when nitrogen and carbon-trading programs get established and assist coastal managers is assessing the ecosystem services of kelp farms. Finally, although this toolkit was assembled and tested in kelp farms only, lessons on the partnership between kelp farmers and scientists may provide other opportunities to develop toolkits to facilitate data collection on other species of seaweeds. Notes Schery Umanzor, College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Juneau 99801, USA sumanzor@ alaska.edu Melissa Good, Kodiak Seafood and Marine Science Center, Alaska Sea Grant, Kodiak, AK 99615, USA has become increasingly important for its ability to involve many contributors to generate observations at scale, which was often unattainable by individual researchers and coastal managers. This partnership between scientists and kelp farmers is also helping researchers access local knowledge and implement coordinated solutions that might take longer otherwise. Following this principle of cooperation, the NET was developed to allow farmers (and other end-users) to collect tissue and water samples to determine carbon and nitrogen removal. It was designed to be self-contained in a plastic case, approximately 48 × 36 × 12 cm, with all materials for sampling. The toolkit is equipped with a water sampler, high-density polyethylene (HDPE) bottles, a syringe, 45-µm HDPE syringe filters, a tissue cutter, silica beads, bags, an information booklet, a fully illustrated protocol detailing where and how to collect tissue and water samples, in addition to key environmental parameters. Given that nutrient determination cannot be conducted in the field, the information booklet provides information related to processing laboratories and guidelines for preparing samples for shipping. To this end, the NET also includes coolers and ice packs as part of the package. The participation of kelp farmers distributed across large geographical areas was key to optimizing the sampling protocol. Studies on kelp physiology show that tissue carbon and nitrogen content may vary, depending on which section of the sporophyte or blade is sampled (Stephens and Hepburn 2016, Endo et al. 2020). Multiple assessments were performed before determining the best section of the blade to be sampled for obtaining reliable and reproducible results (Fig. 3). Quantifying potential differences in tissue carbon and nitrogen content along the blade is of paramount importance because samples obtained from highly variable sections may underestimate or overestimate nutrient removal capacity by kelp farms. Analyses ( C O N T I N U E D O N P A G E 5 2 ) FIGURE 4. Average percentage of carbon (A), nitrogen (B) and carbon to nitrogen ratio (C) measured from basal, middle, and tip sections of farmed sugar kelp Saccharina latissima blades collected at harvest with Nutrient Extraction Toolkits (NET©) over two consecutive farming seasons.
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