SoundToxins: A Research and Monitoring Partnership for Harmful Phytoplankton in Washington State.

The more frequent occurrence of marine harmful algal blooms (HABs) and recent problems with newly-described toxins in Puget Sound have increased the risk for illness and have negatively impacted sustainable access to shellfish in Washington State. Marine toxins that affect safe shellfish harvest because of their impact on human health are the saxitoxins that cause paralytic shellfish poisoning (PSP), domoic acid that causes amnesic shellfish poisoning (ASP), diarrhetic shellfish toxins that cause diarrhetic shellfish poisoning (DSP) and the recent measurement of azaspiracids, known to cause azaspiracid poisoning (AZP), at low concentrations in Puget Sound shellfish. The flagellate, Heterosigma akashiwo, impacts the health and harvestability of aquacultured and wild salmon in Puget Sound. The more recently described flagellates that cause the illness or death of cultivated and wild shellfish, include Protoceratium reticulatum, known to produce yessotoxins, Akashiwo sanguinea and Phaeocystis globosa. This increased incidence of HABs, especially dinoflagellate HABs that are expected in increase with enhanced stratification linked to climate change, has necessitated the partnership of state regulatory programs with SoundToxins, the research, monitoring and early warning program for HABs in Puget Sound, that allows shellfish growers, Native tribes, environmental learning centers and citizens, to be the "eyes on the coast". This partnership enables safe harvest of wholesome seafood for consumption in the region and helps to describe unusual events that impact the health of oceans, wildlife and humans.

Hiding in plain sight: Shellfish-killing phytoplankton in Washington State.

Summer bivalve shellfish mortalities have been observed in Puget Sound for nearly a century and attempts to understand and mitigate these losses have been only partially successful. Likewise, the understanding of the environmental conditions triggering shellfish mortalities and successful strategies for their mitigation are incomplete. In the literature, phytoplankton have played only a cursory role in summer shellfish mortalities in Washington State because spawning stress and bacteria were thought to be the primary causes. In recent years, the occurrence of Protoceratium reticulatum (Claparede & Lachmann) Buetschli and Akashiwo sanguinea (Hirasaka) Hansen & Moestrup, have been documented by the SoundToxins research and monitoring partnership in increasing numbers and duration and have been associated with declining shellfish health or mortality at various sites in Puget Sound. Blooms of these species occur primarily in summer months and have been shown to cause mass mortalities of shellfish in the U.S. and other parts of the world. In 2016-2017, yessotoxins (YTX) were measured in several species of Puget Sound bivalve shellfish, with a maximum concentration of 2.20 mg/kg in blue mussels, a value below the regulatory limit of 3.75 mg/kg established by the European Union for human health protection but documented to cause shellfish mortalities in other locations around the world. In July 2019, a bloom of P. reticulatum coincided with a summer shellfish mortality event, involving a dramatic surfacing of stressed, gaping Manila clams, suggesting that YTX could be the cause. YTX concentrations in their tissues were measured at a maximum of 0.28 mg/kg and histology of these clams demonstrated damage to digestive glands. A culture of P. reticulatum, isolated from North Bay during this massive bloom and shellfish mortality event, showed YTX reaching 26.6 pg/cell, the highest recorded toxin quota measured in the U.S. to date. Concentrations of YTX in phytoplankton samples reached a maximum of 920 ng/L during a P. reticulatum bloom in Mystery Bay on 13 August 2019 when cell abundance reached 1.82 million cells/L. The highest cellular YTX quota during that bloom that lasted into September was 10.8 pg/cell on 3 Sept 2019. Shellfish producers in Washington State have also noted shellfish larvae mortalities due to A. sanguinea passing through filtration intake systems into hatchery facilities. Early warning of shellfish-killing harmful algal bloom (HAB) presence in Puget Sound, through partnerships such as SoundToxins, provides options for shellfish growers to mitigate their effects through early harvest, movement of shellstock to upland facilities, or enhanced filtration at aquaculture facilities.

Confirmation of the shell-boring oyster parasite Polydora websteri (Polychaeta: Spionidae) in Washington State, USA.

Invasions by shell-boring polychaetes such as Polydora websteri Hartman have resulted in the collapse of oyster aquaculture industries in Australia, New Zealand, and Hawaii. These worms burrow into bivalve shells, creating unsightly mud blisters that are unappealing to consumers and, when nicked during shucking, release mud and detritus that can foul oyster meats. Recent findings of mud blisters on the shells of Pacific oysters (Crassostrea gigas Thunberg) in Washington State suggest a new spionid polychaete outbreak. To determine the identity of the polychaete causing these blisters, we obtained Pacific oysters from two locations in Puget Sound and examined them for blisters and burrows caused by polychaete worms. Specimens were also obtained from eastern oysters (Crassostrea virginica Gmelin) collected in New York for morphological and molecular comparison. We compared polychaete morphology to original descriptions, extracted DNA and sequenced mitochondrial (cytochrome c oxidase I [mtCOI]) and nuclear (small subunit 18S rRNA [18S rRNA]) genes to determine a species-level molecular identification for these worms. Our data show that Polydora websteri are present in the mud blisters from oysters grown in Puget Sound, constituting the first confirmed record of this species in Washington State. The presence of this notorious invader could threaten the sustainability of oyster aquaculture in Washington, which currently produces more farmed bivalves than any other US state.

It's a wormy world: Meta-analysis reveals several decades of change in the global abundance of the parasitic nematodes Anisakis spp. and Pseudoterranova spp. in marine fishes and invertebrates.

The Anthropocene has brought substantial change to ocean ecosystems, but whether this age will bring more or less marine disease is unknown. In recent years, the accelerating tempo of epizootic and zoonotic disease events has made it seem as if disease is on the rise. Is this apparent increase in disease due to increased observation and sampling effort, or to an actual rise in the abundance of parasites and pathogens? We examined the literature to track long-term change in the abundance of two parasitic nematode genera with zoonotic potential: Anisakis spp. and Pseudoterranova spp. These anisakid nematodes cause the disease anisakidosis and are transmitted to humans in undercooked and raw marine seafood. A total of 123 papers published between 1967 and 2017 met our criteria for inclusion, from which we extracted 755 host-parasite-location-year combinations. Of these, 69.7% concerned Anisakis spp. and 30.3% focused on Pseudoterranova spp. Meta-regression revealed an increase in Anisakis spp. abundance (average number of worms/fish) over a 53 year period from 1962 to 2015 and no significant change in Pseudoterranova spp. abundance over a 37 year period from 1978 to 2015. Standardizing changes to the period of 1978-2015, so that results are comparable between genera, we detected a significant 283-fold increase in Anisakis spp. abundance and no change in the abundance of Pseudoterranova spp. This increase in Anisakis spp. abundance may have implications for human health, marine mammal health, and fisheries profitability.