Divergence in salinity tolerance of northern Gulf of Mexico eastern oysters under field and laboratory exposure

• Published in: Conservation physiology Vol. 9; no. 1; pp. 1 - coab065
• Main Authors: Marshall, Danielle A, Casas, Sandra M, Walton, William C, Rikard, F Scott, Palmer, Terence A, Breaux, Natasha, La Peyre, Megan K, Beseres Pollack, Jennifer, Kelly, Morgan, La Peyre, Jerome F
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.01.2021
• Subjects: Analysis; Crassostrea; Environmental aspects; Global temperature changes; Oysters; Physiological aspects; Salinity; Gulf of Mexico; local adaptation; bivalves; Editor: Dr Steven Cooke; restoration; climate change; Aquaculture
• ISSN: 2051-1434; 2051-1434
• DOI: 10.1093/conphys/coab065

Using field and laboratory studies, we provide evidence of adaptation to local salinity regimes in the progenies of US Gulf of Mexico eastern oysters from estuaries differing substantially in annual mean salinity. Determining specific adaptations of oysters to local environmental conditions is important for conservation, restoration and the expanding aquaculture industry. Abstract The eastern oyster, Crassostrea virginica, is a foundation species within US Gulf of Mexico (GoM) estuaries that has experienced substantial population declines. As changes from management and climate are expected to continue to impact estuarine salinity, understanding how local oyster populations might respond and identifying populations with adaptations to more extreme changes in salinity could inform resource management, including restoration and aquaculture programs. Wild oysters were collected from four estuarine sites from Texas [Packery Channel (PC): 35.5, annual mean salinity, Aransas Bay (AB): 23.0] and Louisiana [Calcasieu Lake (CL): 16.2, Vermilion Bay (VB): 7.4] and spawned. The progeny were compared in field and laboratory studies under different salinity regimes. For the field study, F1 oysters were deployed at low (6.4) and intermediate (16.5) salinity sites in Alabama. Growth and mortality were measured monthly. Condition index and Perkinsus marinus infection intensity were measured quarterly. For the laboratory studies, mortality was recorded in F1 oysters that were exposed to salinities of 2.0, 4.0, 20.0/22.0, 38.0 and 44.0 with and without acclimation. The results of the field study and laboratory study with acclimation indicated that PC oysters are adapted to high-salinity conditions and do not tolerate very low salinities. The AB stock had the highest plasticity as it performed as well as the PC stock at high salinities and as well as Louisiana stocks at the lowest salinity. Louisiana stocks did not perform as well as the Texas stocks at high salinities. Results from the laboratory studies without salinity acclimation showed that all F1 stocks experiencing rapid mortality at low salinities when 3-month oysters collected at a salinity of 24 were used and at both low and high salinities when 7-month oysters collected at a salinity of 14.5 were used.