Distribution of the highly toxic clinging jellyfish Gonionemus sp. around the island of Martha’s Vineyard, Massachusetts, USA

• Main Authors: Mary R. Carman, David W. Grunden, Emily Reddington, Annette F. Govindarajan
• Format: Article
• Language: English
• Published: BMC 2019-05-01
• Series: Marine Biodiversity Records
• Subjects: Gonionemus; Hydrozoa; Martha’s Vineyard; Polyp; Cyst; Asexual reproduction
• Online Access: http://link.springer.com/article/10.1186/s41200-019-0166-5

Abstract In recent years, the cryptogenic and often highly toxic hydrozoan Gonionemus sp. has appeared in new locations around the globe and has become increasingly abundant in the Northwest Atlantic where it is now associated with severe stings. Several such stings have been documented from the island of Martha’s Vineyard, located approximately 8 km south of the Cape Cod, Massachusetts coast. It appears that Gonionemus sp. may be expanding its range in this region. Here we surveyed for medusae in the major coastal ponds along the perimeter of Martha’s Vineyard, refined our knowledge of Gonionemus sp. habitat by recording salinity, water depth, and bottom type from surveyed areas, and obtained a basic population life history assessment by measuring the sizes and sex ratios of medusae collected in the surveys. We found Gonionemus sp. present in five ponds: Farm Pond, Sengekontacket Pond, Lake Tashmoo, Stonewall Pond, and Edgartown Great Pond. Medusae were associated with eelgrass meadows in all cases. Salinities for medusa populations ranged from 18 ppt in Edgartown Great Pond to 29 ppt in the other ponds. The Farm Pond and Stonewall Pond medusae were significantly smaller than those from other ponds and were comprised of primarily immature individuals despite sampling relatively later in the season, suggesting factors other than temperature may be affecting medusa growth. For mature medusae, sex ratios were highly biased, suggesting a strong clonal component to population growth. Edgartown Great Pond contained only males and thus may represent an entirely clonal population. These medusae are the first record of Gonionemus sp. in Edgartown Great Pond, despite a long history of study. Medusae were most abundant in the portion of the pond near the town landing, which suggests that the medusae could have originated by clonal polyps, frustules, or cysts associated with a boat hull. Given the presence of male and female medusae in other parts of Martha’s Vineyard, it seems likely that additional genetic individuals will arrive in the near future, potentially establishing a sexually reproductive population.