Unexpected reproductive traits of Grateloupia turuturu revealed by its resistance to bleach-based biosecurity protocols

Abstract

A non-indigenous alga, Grateloupia turuturu (Halymeniales, Rhodophyta), was discovered in the Damariscotta Estuary (Maine, USA) in 2017, over 200 km north of its last reported location. Because of the presence of coastal facilities (aquaculture, marine laboratories) among potential vectors, we evaluated a mandated biosecurity protocol, namely, seawater treated with bleach at 50 ppm (50 mg l−1) free chlorine for ≥2 h and measured using test strips, for lethality against G. turuturu and several native algae. We report unexpected resilience to bleach-treatment (Mastocarpus > Grateloupia > Palmaria). Holdfasts of G. turuturu and Mastocarpus stellatus survived 50 and 1000 ppm free chlorine, respectively. Cystocarps on cultured blades of G. turuturu were particularly resistant to bleach-treatment; they produced outgrowths on fragmenting blades that became fertile tetrasporophytes in culture, suggesting reproductive adaptations of cystocarps to stressful conditions that may have broader evolutionary significance. Juvenile, microscopic crusts of G. turuturu were also bleach-resistant if covered by diatoms, and developed upright axes. Free chlorine test strips were inaccurate in seawater, and their use could increase the risk of failed biosecurity as a vector for invasion. Because chlorination at economic and environmentally safe levels is insufficient, we recommend a combination of treatments for comprehensive biosecurity.

Resilience of cold water aquaculture: a review of likely scenarios as climate changes in the Gulf of Maine

“…The NIS, red macroalga Grateloupia turuturu, spread globally from its native range in Asia, often associated with aquaculture of Asian oysters in other parts of the world. It was recognized as number 312 on the IUCN Global Invasive Species Database (Global Invasive Species Database 2020) and was first reported from Maine in 2017 (Capistrant‐Fossa & Brawley 2019). This invasion appears to be limited to the upper Damariscotta Estuary in a warm pocket with high residence time; however, frequent boat traffic and seasonal transport of shellfish rafts to lower parts of the estuary may lead to its spread outwards.…”

“…Resilience for the aquaculture industry and marine ecosystems in Maine requires stricter biosecurity protocols to limit the spread of NIS (Capistrant‐Fossa & Brawley 2019). The potential for synergistic impact between the pressure of climate change and other major perturbations to the marine ecosystem, such as overfishing and pollution, will also favour establishment of NIS.…”

Effects of Nitrogen Source and Concentration on the Growth and Biochemical Composition of the Red Seaweed Grateloupia turuturu (Halymeniaceae, Rhodophyta)

“…Grateloupia turuturu is a red macroalga originally described in Japan [41] that has now spread nearly all over the world as an invasive species [42]. Traditionally, it is consumed as a sea vegetable in Asia [43,44].…”

Effects of salinity and irradiance on early developmental stages of <italic>Grateloupia turuturu</italic> (Halymeniaceae, Rhodophyta) tetrasporophytes

“…Grateloupia turuturu Y. Yamada 1941 (Halymeniaceae, Rhodophyta) is a red macroalga native to East Asia (Denis et al 2010, Capistrant-Fossa andBrawley 2019). It has a worldwide distribution and is considered an invasive species in many parts of the world (Villalard-Bohnsack and Harlin 1997, Saunders and Withall 2006, D'Archino et al 2007, de Azevedo et al 2015, Bolton et al 2016, Kraemer et al 2017, Petrocelli et al 2020.…”