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Authors Kahn, AE; Durako, MJ
Author Full Name Kahn, Amanda E.; Durako, Michael J.
Title Thalassia testudinum seedling responses to changes in salinity and nitrogen levels
Source JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY
Language English
Document Type Article
Author Keywords ammonium; osmolarity; photosynthesis; salinity; seedlings; Thalassia testudinum
Keywords Plus FLORIDA BAY; GENETIC DIVERSITY; RUPPIA-MARITIMA; TURTLE GRASS; GROWTH; PHOTOSYNTHESIS; TEMPERATURE; GERMINATION; PHOSPHORUS; DISTURBANCES
Abstract The dominant seagrass in Florida Bay, Thalassia testudinum Banks ex Konig, is a stenohaline species with optimum growth around marine salinity (30-40PSU). Previous studies have examined the responses of mature short shoots of T testudinum to environmental stresses. Our goal was to assess responses of seedlings to changes in water chemistry in Florida Bay that might occur as part of the Comprehensive Everglades Restoration Plan (CERP). Specifically, we examined seedling survival, growth, photosynthesis, respiration and osmolality in response to hypo- and hyper-salinity conditions, as well as possible synergistic effects of depleted and elevated ammonium concentrations. The study was conducted in mesocosms on T testudinum seedlings collected during August 2003 near Florida Bay. Hyper- and hypo-saline conditions were detrimental to the fitness of T testudinum seedlings. Plants at 0 and 70PSU exhibited 100% mortality and a significant decrease in survival was observed in the 10, 50 and 60PSU treatments. Increased levels of ammonium further decreased growth in the lower salinity treatments. Seedlings in 30 and 40PSU had the greatest growth. Quantum yield and relative electron transport rate, measured using PAM fluorometry, showed a decrease in photosynthetic performance on either side of the 30-40PSU optimum. Tissue osmolality decreased significantly with decreased salinity but tissue remained consistently hyperosinotic to the media across all salinity treatments. Maintaining negative water potential and allocating more energy to osmoregulation may decrease the productivity of this species in salinity-stress conditions. Our results suggest that the salinity-tolerance limits of this seagrass at the seedling stage are not as broad as those reported for mature plants. Increased fresh water inflow, especially if co-occurring with an increase in water-column ammonium, could negatively affect successful recruitment of T. testudinum seedlings in northern regions of Florida Bay. (c) 2006 Elsevier B.V. All rights reserved.
Author Address Univ N Carolina, Ctr Marine Sci, Dept Biol & Marine Biol, Ctr Marine Sci, Wilmington, NC 28409 USA
Reprint Address Durako, MJ (corresponding author), Univ N Carolina, Ctr Marine Sci, Dept Biol & Marine Biol, Ctr Marine Sci, 5600 Marvin Moss Lane, Wilmington, NC 28409 USA.
E-mail Address durakom@uncw.edu
Times Cited 43
Total Times Cited Count (WoS, BCI, and CSCD) 48
Publisher ELSEVIER
Publisher City AMSTERDAM
Publisher Address RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS
ISSN 0022-0981
29-Character Source Abbreviation J EXP MAR BIOL ECOL
ISO Source Abbreviation J. Exp. Mar. Biol. Ecol.
Publication Date JUL 25
Year Published 2006
Volume 335
Issue 1
Beginning Page 1
Ending Page 12
Digital Object Identifier (DOI) 10.1016/j.jembe.2006.02.011
Page Count 12
Web of Science Category Ecology; Marine & Freshwater Biology
Subject Category Environmental Sciences & Ecology; Marine & Freshwater Biology
Document Delivery Number 055QT
Unique Article Identifier WOS:000238466100001
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