Prolonged low salinity tolerance in Halodule wrightii Asch

• Published in: Aquatic botany Vol. 178; p. 103498
• Main Author: Biber, Patrick
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2022
• Subjects: abiotic stress; biomass; botany; Caribbean; climate change; Flooding; flora; Freshwater; grasses; Gulf of Mexico; habitats; Halodule wrightii; islands; Mississippi; Mississippi River; rivers; Salinity; salt tolerance; seagrasses; Shoalgrass; Tolerance; Mississippi; Gulf of Mexico; Caribbean; Mississippi River; Tolerance; Flooding; Freshwater; Shoalgrass; Salinity
• ISSN: 0304-3770; 1879-1522
• DOI: 10.1016/j.aquabot.2022.103498

The seagrass Halodule wrightii (shoal grass) is found throughout the Caribbean and Gulf of Mexico where it can be an important or dominant component of the flora. It is generally more tolerant to disturbance than other seagrass species, including tolerance to reduced salinity. This study investigated the low salinity tolerance of a population of H. wrightii that has a long history of exposure to river flooding located at Cat Island, Mississippi (MS). Plants were collected after record prolonged flooding of the Mississippi River in 2019 and subsequent reduced salinities at Cat Island, MS, then allowed to recover at a salinity of 25 before being subject to three low salinity exposures of 5, 10, and 15. Plants were still alive after more than 12 months even at the lowest salinity of 5. Morphological and biomass metrics were recorded at the end of this prolonged low-salinity exposure. Plants exhibited low biomass and shoot density. This population of H. wrightii was able to survive very low salinities for longer than previously reported. Other seagrass populations with enhanced tolerance to abiotic stressors may become important for survival as climate change alters coastal habitat conditions. •Shoal grass may have better low salinity tolerance than reported previously.•Plants from Cat Island, Mississippi, survived for > 12 months at 5 ppt salinity.•Biomass and shoot density were reduced over time compared to field measurements.