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Global sea-level rise is transforming coastal ecosystems, especially freshwater wetlands, in part due to increased episodic or chronic saltwater exposure, leading to shifts in biogeochemistry, plant- and microbial communities, as well as ecological services. Yet, it is still difficult to predict how soil microbial communities respond to the saltwater exposure because of poorly understood microbial sensitivity within complex wetland soil microbial communities, as well as the high spatial and temporal heterogeneity of wetland soils and saltwater exposure. To address this, we first conducted a two-year survey of microbial community structure and bottom water chemistry in submerged surface soils from 14 wetland sites across the Florida Everglades. We identified ecosystem-specific microbial biomarker taxa primarily associated with variation in salinity. Bacterial, archaeal and fungal community composition differed between freshwater, mangrove, and marine seagrass meadow sites, irrespective of soil type or season. Especially, methanogens, putative denitrifying methanotrophs and sulfate reducers shifted in relative abundance and/or composition between wetland types. Methanogens and putative denitrifying methanotrophs declined in relative abundance from freshwater to marine wetlands, whereas sulfate reducers showed the opposite trend. A four-year experimental simulation of saltwater intrusion in a pristine freshwater site and a previously saltwater-impacted site corroborated the highest sensitivity and relative increase of sulfate reducers, as well as taxon-specific sensitivity of methanogens, in response to continuously pulsing of saltwater treatment. Collectively, these results suggest that besides increased salinity, saltwater-mediated increased sulfate availability leads to displacement of methanogens by sulfate reducers even at low or temporal salt exposure. These changes of microbial composition could affect organic matter degradation pathways in coastal freshwater wetlands exposed to sea-level rise, with potential consequences, such as loss of stored soil organic carbon.
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This content will become publicly available on September 1, 2026
Maternal nest-site choice in response to saline substrates differs between island and inland populations of lizards
Abstract Nest-site choice influences offspring development and varies in response to specific environmental cues. For species that inhabit coastal regions, salinity of the nest site is probably an important factor for nesting females, whereas this cue is likely to be rare or absent for inland populations. We compared nest-site choice of brown anole lizards (Anolis sagrei) between an island population (that frequently experiences seawater inundation) and an inland population (that rarely, if ever, experiences inundation). We hypothesized that island females would avoid nesting in saline soils more than inland females, because it impairs egg hatching success. We provided females from each population with two different nesting substrates (soil mixed with freshwater vs. saltwater). We incubated their eggs in these conditions to quantify the effects on embryo survival. Island females tended to avoid nesting in saltwater soil, whereas inland females exhibited no preference. Water loss and mortality rates of eggs increased during incubation in soil with saltwater. These patterns imply that females from island populations, but not inland populations, might have adaptive behavioural responses to soil salinity. These results have important implications for understanding how coastal or island populations might respond to changes in salinity under climate change (e.g. sea level rise, increased hurricanes).
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- Award ID(s):
- 1942145
- PAR ID:
- 10653836
- Publisher / Repository:
- AUrora Repository
- Date Published:
- Journal Name:
- Biological Journal of the Linnean Society
- Volume:
- 146
- Issue:
- 1
- ISSN:
- 0024-4066
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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