@article {spivak_salt_2020,
	title = {Salt Marsh Pond Biogeochemistry Changes Hourly-to-Yearly but Does Not Scale With Dimensions or Geospatial Position},
	journal = {Journal of Geophysical Research: Biogeosciences},
	volume = {125},
	year = {2020},
	pages = {e2020JG005664},
	abstract = {Shallow ponds are expanding in many salt marshes with potential impacts on ecosystem functioning. Determining how pond characteristics change over time and scale with physical dimensions and other spatial predictors could facilitate incorporation of ponds into projections of ecosystem change. We evaluated scaling relationships across six differently sized ponds in three regions of the high marshes within the Plum Island Ecosystems-Long Term Ecological Research site (MA, USA). We further characterized diel fluctuations in surface water chemistry in two ponds to understand short-term processes that affect emergent properties (e.g., habitat suitability). Primary producers drove oxygen levels to supersaturation during the day, while nighttime respiration resulted in hypoxic to anoxic conditions. Diel swings in oxygen were mirrored by pH and resulted in successive shifts in redox-sensitive metabolisms, as indicated by nitrate consumption at dusk followed by peaks in ammonium and then sulfide overnight. Abundances of macroalgae and Ruppia maritima correlated with whole-pond oxygen metabolism rates, but not with surface area (SA), volume (V), or SA:V. Moreover, there were no clear patterns in primary producer abundances, surface water chemistry, or pond metabolism rates across marsh regions supplied by different tidal creeks or that differed in distance to upland borders or creekbanks. Comparisons with data from 2 years prior demonstrate that plant communities and biogeochemical processes are not in steady state. Factors contributing to variability between ponds and years are unclear but likely include infrequent tidal exchange. Temporal and spatial variability and the absence of scaling relationships complicate the integration of high marsh ponds into ecosystem biogeochemical models.},
	keywords = {biogeochemistry, ecosystem function, global change, metabolism, salt marsh, scaling},
	issn = {2169-8961},
	doi = {10.1029/2020JG005664},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005664},
	author = {Spivak, Amanda C. and Denmark, Alexander and Gosselin, Kelsey M. and Sylva, Sean P.}
}
@article {spivak_shallow_2018,
	title = {Shallow ponds are biogeochemically distinct habitats in salt marsh ecosystems},
	journal = {Limnology and Oceanography},
	volume = {63},
	year = {2018},
	pages = {1622{\textendash}1642},
	abstract = {Runaway expansion of shallow ponds can catalyze the conversion of vegetated marshes into open water environments. Predicting how this transition affects ecosystem functioning is difficult because little is known about pond biogeochemistry. We characterized sediment organic matter sources and transformations in three ponds with different plant communities, over alternating periods of tidal isolation and flushing, during summer and fall, using a combination of stable isotopes, lipid biomarkers, and benthic fluxes. Sediment respiration rates (1.66 {\textpm} 0.09 mmol C m-2 d-1 to 28.53 {\textpm} 7.76 mmol C m-2 d-1) were comparable to shallow estuaries and driven by sulfate reduction. Rates varied across ponds, reflecting differences in summertime Ruppia maritima and macroalgae abundances, but were similar between seasons. Interactions between aboveground plant and sediment bacterial communities translated into distinct biogeochemical processes across the three ponds. Tidal isolation and summer weather intensified plant and bacterial community effects on pond carbon dynamics, resulting in algal biomass and lipid δ13C values that were 3{\textendash}12{\textperthousand} enriched, compared to nearby habitats. Surface sediment organic matter mainly derived from pond microalgae and was compositionally distinct from tidal creeks and marshes. Surprisingly, sediment bacteria were not tightly coupled to benthic microalgae but decomposed multiple carbon sources in surface sediments and became increasingly reliant on buried peat at deeper horizons. Pond development over time could largely be explained by sediment respiration and the simultaneous accretion of the surrounding marsh platform. The role of decomposition in pond expansion is consistent with previous assessments based on whole-pond metabolism rates. Consequently, future pond expansion could alter ecosystem biogeochemistry and reduce carbon storage.},
	issn = {1939-5590},
	doi = {10.1002/lno.10797},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lno.10797},
	author = {Spivak, Amanda C. and Gosselin, Kelsey M. and Sylva, Sean P.}
}
