| Summary: | In the nearshore Alaskan Beaufort Sea, discrete, isolated rocky habitats harbor biological communities that are unusually diverse for the region, with markedly different fauna and flora than found in the surrounding soft sediment areas. The boulder fields also support tightly linked food webs, with connections to higher trophic levels such as fishes and seals. These systems are highly vulnerable to disturbances, including sedimentation from human activities and coastal erosion, fluctuations in salinity from seasonal river discharge, and temperature increases from heat influx originating at lower latitudes and from atmospheric warming. Spatial isolation of these boulder fields and the slow development of benthic communities limit ecosystem recovery from disturbance. To assess the possible ecological effects of such environmental disturbances, this field program undertook an investigation of the biological communities and environmental conditions across the Stefansson Sound Boulder Patch, the largest of the Beaufort Sea nearshore boulder fields. The overlying objectives of this program were to: 1) monitor incident and in situ photosynthetically active radiation (PAR), salinity, temperature, currents, and pH to define the spatial variability in annual kelp productivity and biomass; 2) characterize benthic community structure changes across environmental gradients in the Boulder Patch and 3) collect annual measurements of kelp growth in the Boulder Patch to provide a nearly continuous record of kelp growth since 1976. Within and in addition to these objectives, individual research projects were completed, using experimental approaches, timeseries analysis and historical data to gain an in depth understanding of mechanisms (past and present) that resulted in the Boulder Patch community we see today and how this community may vary in future conditions. These datasets here result from ecosystem studies and monitoring that took place from 2015 to 2018 at multiple sites in Stefansson Sound, Alaska. To examine drivers of spatial differences in community structure, benthic community structure was assessed via percent cover and colonization was aessessed via settlement plates.
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