Salinity Thresholds for Understory Plants in Coastal Wetlands.

The effects of sea level rise and coastal saltwater intrusion on wetland plants can extend well above the high-tide line due to drought, hurricanes, and groundwater intrusion. Research has examined how coastal salt marsh plant communities respond to increased flooding and salinity, but more inland coastal systems have received less attention. The aim of this study was to identify whether ground layer plants exhibit threshold responses to salinity exposure. We used two vegetation surveys throughout the Albemarle-Pamlico Peninsula (APP) of North Carolina, USA to assess vegetation in a low elevation landscape (< 3.8 m) experiencing high rates of sea level rise (3-4 mm/year). We examined the primary drivers of community composition change using Non-metric Multidimensional Scaling (NMDS), and used Threshold Indicator Taxa Analysis (TITAN) to detect thresholds of compositional change based on indicator taxa, in response to potential indicators of exposure to saltwater (elevation, Na, and the S Ca + Mg). Salinity and elevation explained 64% of the variation in community composition, and we found two salinity thresholds for both soil Na+ (265 and 3843 g Na+/g), and Ca+ + Mg+ (42 and 126 µeq/g ) where major changes in community composition occur on the APP. Similar sets of species showed sensitivity to these different metrics of salt exposure. Overall, our results showed that ground layer plants can be used as reliable indicators of salinity thresholds in coastal wetlands. These results can be used for monitoring salt exposure of ecosystems and for identifying areas at risk for undergoing future community shifts.

Inoculating rhizome-propagated Sporobolus pumilus with a native mycorrhizal fungus increases salt marsh plant growth and survival

Salt marshes are ecosystems of significant ecological importance for coastal stability and fundamental roles in marine ecosystems. Salt marshes are declining due to anthropogenic and natural causes including sea level rise. Coastal restoration efforts have increased worldwide, but many fail in long-term coastal stability. We used a naturally occurring arbuscular mycorrhizal fungus (AMF) to test whether survival and early growth of the salt marsh grass Sporobolus pumilus (formerly Spartina patens) improved under simulated salt marsh conditions. Using a tidal mesocosm bench, we grew inoculated plants with varying AMF treatments under simulated tidal regimes to determine if AMF could aid in establishment of healthy Sporobolus communities. Rhizome-derived S. pumilus had greater survival and grew faster than seed-derived plants. Plants inoculated with propagated AMF consistently outperformed both sterile and native sediment controls in terms of plant survival and growth. Use of rhizome-derived Sporobolus inoculated with propagated Funneliformis geosporum showed the most promise in producing successful plant populations for salt marsh restoration. This may be due to plant life stage and improved plant nutrient status, allowing rhizome-derived plants to grow more quickly than seed-derived plants. Using these plants in future large-scale restoration may increase re-establishment of salt marsh ecosystems.

Molecular identification and phylogenetic analysis of suaeda maritima from parangipettai coastal areas, southeast coast of india

Conventional taxonomy is limited with delineating species and controversies arise with DNA barcoding based identifications. Hence, an alternative supporting approach is very much needed to identify species and differentiate them within the species based on the genetic material. 18S rRNA genes have been particularly helpful in analyzing phylogeny at the species level. In addition, bioinformatics which represents a new, growing area of science uses computational approaches to answer biological questions. Salt tolerant costal salt marsh plant of Suaeda maritima was selected for 18s rRNA sequencing to solve the ambiguity in itsspecies level identification. Similarity search of study species shared 99% similarity with 5 species of Atriplex canescens clone s128, Atriplex torreyi var. griffithsii clone p508, Spinacia oleracea, Oenothera laciniata clone,Beta vulgaris. Phylogenetic tree infer that S.maritima is closely related to Spinacia oleracea and Oenothera laciniata. Atriplex canescens (fourwing saltbush), Atriplex torreyi and Phaulothamnus spinescens, Celosia argentea found to be closely related and are in one group. Hence, this study result clearly shows thus study species evaluated from angiosperm and provides key step in understanding the evolution of salt tolerance in angiosperm.