Conductivity Temperature Depth (CTD) data from the Norseman II (NRS22-1s and NRS22-2s), as part of the 2022 Origin and Fate of Harmful Algal Blooms in the Warming Chukchi Sea cruise

### Access

Data files can be accessed via: https://arcticdata.io/data/10.18739/A2B853K56

### Overview

This data was collected as part of the NSF-funded program, Origin and Fate of Harmful Algal Blooms in the Warming Chukchi Sea. The fieldwork was comprised of two back-to-back cruises, Leg 1 (1S), and Leg 2 (2S), on the R/V Norseman II during the summer months of 2022. This submission contains the shipboard conductivity-temperature-depth (CTD) data collected. The Pacific sector of the Arctic Ocean is warming, in particular the shallow Chukchi Sea. As a result, many organisms may spread into Arctic waters, and some present significant threats to human and ecosystem health, such as harmful algal bloom (HAB) species (commonly called red tides). The investigators present evidence that HABs occur in the Chukchi Sea and we know that the potent neurotoxins they produce can affect marine mammals, seabirds, and other resources critical to subsistence harvesters. At the same time, little is known about the present and future risk from toxic algae to humans in the Pacific Arctic region. This study was the first to document the current distribution of highly toxic HAB species at high resolution over large spatial scales within the Alaskan Arctic and along its transport pathways and will provide estimates of areas at high risk of toxicity now and in a warming future. The hypothesis underlying this project is that harmful algal bloom species (HABs) in Alaskan Arctic waters are not only advected from the south through Bering Strait but are now originating locally on the Chukchi shelf due to warming temperatures, circulation dynamics, and water mass structure that influence bloom magnitude, duration, toxicity, and recurrence. This was addressed through a joint physical-biological field and laboratory program to study the relationship between HAB species distribution/dynamics and the physical environment of the Chukchi Sea region. The distribution of HAB species on the Chukchi shelf was mapped in relation to hydrography and circulation, including a comprehensive survey of the Alaskan Coastal Current which transports the warmest water in the Chukchi Sea. This submission contains data from the hydrographic survey portion of this survey.