Poster presented at the Northeast Algal Society meeting in April 2026.
by Jordan Chalfant and Amanda Savoie
Between 2021 and 2025, we conducted routine sampling and DNA barcoding to build a reference library for Maine’s marine macroalgal flora and to support our in-progress field guide to the seaweeds of Maine. This work yielded nine new molecularly-confirmed state records and two significant range expansions, demonstrating that DNA barcoding substantially enhances regional biodiversity inventories and improves detection of both cryptic diversity and shifting species distributions in the Gulf of Maine.
Gracilaria
vermiculophylla
First record in Maine
Aglaothamnion cf. pseudobyssoides
First record in Maine
Gaillona rosea
First record in Maine
Seirospora cf. interrupta
First record in Maine
Antithamnion spirographidis
First record in Maine, first molecular record in the Northwest Atlantic
Dasya pedicellata
First indication of two genetic groups in Maine, range expansion
Acanthosiphonia echinata
First record in Maine
Bryocladia subtilissma
First molecular record in the Northwest Atlantic
Melanothamnus cf. eastwoodiae
First record in Maine
Leptosiphonia brodiei
First record in Maine
Ulva sp.
Unknown taxon, possible first record for the United States
| Species | Collection years | Maine collection locations | Status (native / introduced) | Type locality | Relevance | Previously known Western Atlantic distribution |
| Gracilaria vermiculophylla (Ohmi) Papenfuss | 2023 & 2025 | Freeport, Damariscotta, York, & Mount Desert Island | Introduced | Gomejima, Akkeshi Bay, Japan | First record in Maine, abundant and widely-distributed | Northern limit reportedly Great Bay Estuary in 2003. Not found in southern Maine during targeted sampling effort in 2013 (Nettleton 2013) |
| Grateloupia turuturu Yamada View mini-guide | 2025 | Walpole & Kittery | Introduced | Hokkaido, Japan | Range expansion | Northern limit reportedly Great Bay Estuary in 2014, with a disjunct population on the Damariscotta River established 2017 (Mathieson & Dawes 2017; Maine Sea Grant 2018) |
| Aglaothamnion cf. pseudobyssoides (P.Crouan & H.Crouan) Halos | 2025 | South Berwick | Unknown, likely introduced | Kervallon, France | First record in Maine, first molecular record in the Western Atlantic | Northern limit North Carolina (AlgaeBase) or Nova Scotia (Schneider & Searles 1991, as Callithamnion pseudobyssoides) |
| Gaillona rosea (Roth) Athanasiadis | 2025 | Edgecomb, Wiscasset, Verona Island | Native or present since ~1850s | Bayonne, France | First record in Maine, first molecular record in the Western Atlantic | New Jersey to Massachusetts (Taylor 1957, as Callithamnion roseum). General reference to Nova Scotia distribution in Mathieson & Dawes (2017, as Aglaothamnion roseum) |
| Seirospora cf. interrupta (Smith) F.Schmitz | 2024 & 2025 | Bar Harbor, Lamoine, & Penobscot Bay | Native? | Brighton, England | First record in Maine, first molecular record in the Western Atlantic, possibly genetically distinct from Eastern Atlantic S. interrupta | Found from Massachusetts south. Also recorded at St. Margarets Bay, Nova Scotia in the mid-1980s (Bird 1985) |
| Antithamnion cf. sparsum Tokida View mini-guide | 2021 & 2025 | Bar Harbor | Introduced | Sakhalin, Japan | First record in United States, recently discovered in the Western Atlantic | First records from three sites off the south shore of Nova Scotia, August, 2021 (Brooks 2023) |
| Antithamnionella spirographidis (Schiffner) E.M. Wollaston | 2025 | Verona Island & Stockdon Springs | Introduced | Trieste, Italy | First record in Maine, recently discovered in the Western Atlantic | First record from Chatham Harbor, Massachusetts in 2023 (Irvine 2024) |
| Dasya pedicellata (C.Agardh) C.Agardh | 2025 | Brunswick | Native | New York, USA | First molecular record & first indication of two genetic groups in Maine, range expansion | Southern Cape Cod to New York, also Rhode Island (Saunders 2024) |
| Acanthosiphonia echinata (Harvey) Savoie & G.W.Saunders | 2025 | Newcastle | Native | Key West, Florida | First record in Maine | Previously known from North Carolina south, with recent records from Massachusetts, New Brunswick, and Nova Scotia (Irvine 2024, Savoie 2019) |
| Bryocladia subtilissma (Montagne) Díaz-Tapia | 2025 | Newcastle, York, & Berwick | Native | Cayenne, French Guiana | First molecular record in the Northwest Atlantic | Historic records (lacking molecular confirmation) throughout the NWA |
| Melanothamnus cf. eastwoodiae (Setchell & N.L.Gardner) Díaz-Tapia & Maggs | 2025 | West Bath | Introduced | Baja California, México | First record in Maine | First recorded in the Western Atlantic 2022 in New Brunswick, more recently documented in Rhode Island and Massachusetts (Saunders 2025) |
| Leptosiphonia brodiei (Dillwyn) Savoie & G.W.Saunders 2018 | 2025 | Kittery | Introduced | Bantry Bay, Ireland | First record in Maine, first molecular confirmation in the Northwest Atlantic | Several 1970s records from eastern Canada (Hooper 1977). Hommersand voucher from Buzzard’s Bay, Massachusetts, 1982. Globally distributed and possibly prone to temporary introduction |
| Ulva sp. 10GWS | 2025 | Lubec | Unknown | Undescribed | Unknown taxon, possible first record for United States | Distribution unknown, first molecular record from 2022 (Savoie, unpublished), either overlooked owing to cryptic morphology or recently introduced |
Table of selected highlights. See the complete poster above for additional context and details.