More of the latest from the Wetlands Lab

Following is the abstract of a manuscript currently in press at the Journal of Coastal Research.

The response of photosystem II to soil salinity and nutrients in wetland plant species of the northwestern Gulf of Mexico
Eric N. Madrid, Anna R. Armitage, and Antonietta Quigg

The photosynthetic response of many wetland plant species to soil salinity and nutrients has been described in the laboratory, but less is known about the cumulative effect of these abiotic factors in the natural environment. In this investigation we correlated field measurements of chlorophyll fluorescence with simultaneous measurements of soil nitrogen and phosphorus content, soil salinity, and relative leaf nitrogen content in four species (Spartina alterniflora Loisel, S. patens (Aiton) Muhl, Schoenoplectus californicus (C.A. Mey.) Steud. and S. robustus (Pursh) M.T. Strong), that are common in brackish and salt marshes of the northwestern Gulf of Mexico. We found that the range of environmental conditions experienced by each species in the field is greater than what has been considered in laboratory investigations, and that saline soils may elicit an inverse photochemical response that has not been documented in the laboratory. The relationship between chlorophyll fluorescence and soil N:P ratio was not significant in S. alterniflora, nonlinear in S. patens and S. robustus, and significant and positive in S. californicus. The relationship between leaf nitrogen content and effective quantum yield was significant and positive in S. alterniflora and S. robustus, but only S. alterniflora appeared to be able to increase relative leaf nitrogen content over a wide range of soil nutrient and salinity regimes. S. californicus had the greatest potential for photosynthetic light capture but also had the narrowest ecological distribution. Thus, the species best adapted to high levels of abiotic stress (S. alterniflora) was less dominant at lower salinities, and species with the highest potential for photosynthetic performance (S. robustus and S. californicus) were only found in locations with favorable abiotic conditions.

The research in this article was supported by grants from the Texas General Land Office, Oil Spill and Response Division, and from the GLO Coastal Management Program.