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Date of Original Version



Biological Sciences


Temperate coastal estuaries worldwide, such as Narragansett Bay, Rhode Island, are influenced by seasonal macroalgal blooms (e.g., Ulva) during warm months, whereas bloom-forming macroalgae are rarely encountered during winter. We assessed the ability of distromatic Ulva to overwinter through fragments, recruits, and/or microscopic propagules. We documented (a) small tissue fragments in sediment cores and the water column, (b) recruits and microscopic propagules on field-based settlement tiles, and (c) production of reproductive propagules, throughout the winter months. Laboratory culturing experiments indicated that both fragments and propagules are viable. Our data indicate that bloom-forming overwintering Ulva simultaneously use multiple reproductive strategies.