Title
Project Chariot Revisited: Cape Thompson Coastal Lagoons Ecological Investigations Final Report
Author(s)
Kevin Fraley; Michael Lunde; Martin Robards
Published
2022
Abstract
The southeastern Chukchi Sea is a seasonally productive marine ecosystem. Nearshore habitats are heavily used by local people for subsistence harvest; they also provide important foraging habitat, proximity to shelter, and overwintering habitat for many ecologically and locally important fish species (Craig 1984; George et al. 2007; Johnson et al. 2007; Whiting et al. 2011; Logerwell et al. 2015). Coastal lagoons are a dominant landscape feature in this region, comprising over a third (37%) of the Arctic coastline between Wales and the Canadian border (Figure 1). These bodies of water provide critical habitat for migratory fish (e.g., Pacific salmon and whitefishes) and other ecologically important forage fish (e.g., Pacific herring and pond smelt), as well as staging habitat for migratory shorebirds and waterfowl. Coastal residents are increasingly interested in documenting the ecology and importance of fish and invertebrates in these lagoons due to concerns about potential impacts from climate change, increased human development, and the possibility of coastal oil spills (LGL 2011; Rand and Logerwell 2011). Previously, the two most significant lagoon research efforts between Kivalina and Cape Thompson along the Chukchi coast occurred in the 1950s as part of the Project Chariot Environmental Assessment (Johnson 1961; Willimovsky and Wolfe 1966; Tash and Armitage 1967; Tash 1971) and the Environmental Assessment for the Red Dog Mine port facility (Dames and Moore 1983). Apart from these research efforts, little has been published about the ecology of coastal habitats of this area, despite their importance for food security and ecosystem health. Our research efforts during summer 2018 focused on the coastal areas around Cape Thompson in the North Slope Borough of Alaska, addressing the need for current baseline information on the structure and function of lagoons in the area. Four lagoons were visited within the boundary of the North Slope Borough during 2018: Kemegrak, Akoviknak, Atosik, and Mapsorak. We also sampled one additional lagoon in 2018 (Singoalik) just south of the others, in the Northwest Arctic Borough. Logistic constraints and the Covid-19 Pandemic precluded a repeat visit in 2019 and 2020, respectively. In 2021, Atosik, Mapsorak (North Slope Borough), and Singoalik Lagoons (Northwest Arctic Borough) were revisited. We collected data in both 2018 and 2021 on physical water parameters including primary productivity, with samples at 4-7 individual sites per lagoon, based on established protocols developed as part of the National Park Service’s Arctic Lagoon Vital Signs (Jones and Apsens 2017). We surveyed fish assemblage composition and abundance using a beach seine and experimental gill net during both years of sampling, and performed zooplankton tows at each study site in 2018 (3-5 tows per lagoon). Lagoon connectivity to the ocean was assessed during site visits and via Sentinel-2 daily-weekly satellite imagery. Additionally, we recorded presence and activity of waterbirds at each lagoon. Physiochemical parameters varied between lagoons, and within lagoons between years. None of the lagoons sampled were open to the marine environment at the time of sampling in 2018, and only Singoalik Lagoon was connected to the ocean in 2021. Temperature readings varied between lagoons and years, with the highest overall temperature occurring at Kemegrak Lagoon (16.35 ± 1.82°C) and the lowest at Mapsorak (8.86 ± 0.25°C). Salinity levels at all lagoons were relatively low, except for at Singoalik in 2021, where a marine connection was present. Low salinity levels and higher temperature readings likely reflect the absence of recent influxes of colder saline water from the marine system in the other lagoons. Reliable marine connections generally exist in the lagoons of nearby Cape Krusenstern (Smith et al. 2019a), which are typically open to the marine environment in the spring, but gradually close as summer progresses. Temperature readings in Cape Thompson lagoons recorded in the 1983 report by Dames and Moore, for instance, also revealed lower overall temperatures at lagoons open to the marine environment, particularly at sample stations directly inside the mouth of the lagoon, indicating that influx of colder water from the ocean has significant impact on the overall temperature in the main body of the lagoon. Primary production was highest at Kemegrak Lagoon in 2018, and blue-green algae concentrations in lagoons during that year indicated algal blooms may be common. Zooplankton assemblages were predominantly freshwater and brackish in nature in Akoviknak, Kemegrak, and Atosik Lagoons in both the 1960s and in 2018. The most common taxa were Daphnia middendorffiana, Limnocalanus johanseni, and Cyclops vernalis. Singoalik Lagoon contained more marine species during both periods (1960s and 2018), presumably due to its seasonal connection to the ocean. Overall, there were minor changes in zooplankton composition within individual lagoons in the ~60 years between sampling, except in Mapsorak Lagoon, where marine-oriented taxa were replaced by freshwater species, which is consistent with being closed to the ocean at the time of sampling. In 2018, we recorded 264 total fish comprising seven species, and one unidentified larval fish. In 2021, we found 183 total fish comprising six species, and several unidentified larval fishes. Highest species diversity occurred at Singoalik Lagoon during both years sampled. This is consistent with our work in the Cape Krusenstern area where lagoons connected to the ocean generally had higher fish diversity. Fishes of the largest size class (100-199mm and 200+mm) were found in 2018 at Akoviknak, all of which were least cisco, while 100-199mm starry flounder and a 300+mm humpback whitefish were captured in Singoalik in 2021. Sampling at both Atosik and Mapsorak did not yield any fish during either year they were visited. Important forage species captured included ninespine stickleback, pond smelt, threespine stickleback, and capelin. Interestingly, humpback whitefish and capelin were found in 2021 but were not present in 2018, while ninespine stickleback, least cisco, and pond smelt were sampled in 2018 but were absent in 2021. Dolly Varden, cod species, and pink salmon were found in Singoalik Lagoon in 1959 and 1983, or were noted anecdotally by subsistence fishers, but were not encountered in 2018 and 2021. We conducted opportunistic informal interviews with members of the local community through chance encounters during fieldwork, telephone correspondence, and a 2018 visit to Point Hope. Conversations with Kivalina and Point Hope residents indicate that multiple subsistence activities occur throughout the year along the coast from Chariot to Singoalik Lagoon, including hunting, beachcombing, fishing, and seabird egg-gathering, and Point Hope community members were keen to see more scientific monitoring in the area. Point Hope residents also indicated that the lagoons north of Chariot have been consistently closed during the last decade. Overall, our results are consistent with our work in the Cape Krusenstern and Bering Land Bridge National Park Units – specifically, that the most productive, biodiverse lagoons are those that for at least part of the early season are connected to the ocean. With respect to spill response, it would be these lagoons with regular connection that provide the most important seasonal habitats for fish of both ecological and subsistence importance. Within this study Singoalik was the most ecologically valuable (Northwest Arctic Borough) followed by Akoviknak (North Slope Borough). The other coastal lagoons around Cape Thompson did not appear to have any regular connectivity with the ocean in recent times.
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