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ABSTRACT Rural shellfish harvesters, including many Alaska Native peoples, require safe access to wild shellfish for subsistence, food security, and cultural practices. However, wild shellfish may be contaminated with paralytic shellfish toxins, leaving harvesters with increased risks of significant illness or death. To manage these risks, the Sitka Tribe of Alaska Environmental Research Lab (STAERL) was established to test shellfish samples sent in by harvesters in the community and to support regular monitoring of select local beaches by tribal governments. Here, we investigated harvester utilization of this shellfish testing service from 2016-2024, comprising 299 samples sent in by local harvesters, and used generalized linear models to examine how annual testing rates varied by year, location, species, and species-based detoxification rates. We pay particular attention to differences that may reflect the influence of risk perceptions and accessibility of harvesting and testing on utilization (DOI: 10.5061/dryad.dfn2z35dr). We find that testing utilization has increased through time (1.278, 95% CI: 1.161, 1.407), testing rates are highest in spring and broadly similar between the other three seasons, testing rates in Sitka are much higher than those outside of it, and neither road accessibility nor species-based detoxification rates strongly affect testing rate ratios. These findings suggest that shellfish testing behavior is consistent despite seasonal variations in risk and convenience, but that the STAERL individual testing program provides a pathway to maintain established subsistence harvest practices while reducing poisoning risks. 

Harmful algal blooms (HABs) are a reoccurring threat to subsistence and recreational shellfish harvest in Southeast Alaska. Recent Tribally led monitoring programs have enhanced understanding of the environmental drivers and toxicokinetics of shellfish toxins in the region; however, there is considerable variability in shellfish toxins in some species, which cannot be easily explained by seasonal bloom dynamics. Persistent concentrations of paralytic shellfish toxins (PSTs) in homogenized butter clam samples (n > 6, Saxidomus gigantea) have been observed in several communities, and relatively large spikes in concentrations are sometimes seen without Alexandrium observations or increased toxin concentrations in other species. In order to investigate potential sources of variability in PST concentrations from this subsistence species, we assessed individual concentrations of PSTs across a size gradient of butter clams during a period of relatively stable PST concentrations. We found that increasing concentrations of PSTs were significantly associated with larger clams using a log-linear model. We then simulated six clams randomly sampled from three size distributions, and we determined large clams had an outsized probability of contributing a significant proportion of the total toxicity in a six-clam homogenized sample. While our results were obtained during a period of low HAB activity and cannot be extrapolated to periods of intoxication or rapid detoxification, they have significant ramifications for both monitoring programs as well as subsistence and recreational harvesters. 

The pelagic brown macroalga Sargassum supports rich biological communities in the tropical and subtropical Atlantic region, including a variety of epiphytic invertebrates that grow on the Sargassum itself. The thecate hydroid Aglaophenia latecarinata is commonly found growing on some, but not all, Sargassum forms. In this study, we examined the relationship between A. latecarinata and its pelagic Sargassum substrate across a broad geographic area over the course of 4 years (2015–2018). The distribution of the most common Sargassum forms that we observed ( Sargassum fluitans III and S. natans VIII ) was consistent with the existence of distinct source regions for each. We found that A. latecarinata hydroids were abundant on both S. natans VIII and S. fluitans III , and also noted a rare observation of A. latecarinata on S. natans I . For the hydroids on S. natans VIII and S. fluitans III , hydroid mitochondrial genotype was strongly correlated with the Sargassum substrate form. We found significant population genetic structure in the hydroids, which was also consistent with the distributional patterns of the Sargassum forms. These results suggest that hydroid settlement on the Sargassum occurs in type-specific Sargassum source regions. Hydroid species identification is challenging and cryptic speciation is common in the Aglaopheniidae. Therefore, to confirm our identification of A. latecarinata , we conducted a phylogenetic analysis that showed that while the genus Aglaophenia was not monophyletic, all A. latecarinata haplotypes associated with pelagic Sargassum belonged to the same clade and were likely the same species as previously published sequences from Florida, Central America, and one location in Brazil (São Sebastião). A nominal A. latecarinata sequence from a second Brazilian location (Alagoas) likely belongs to a different species.