I www.JCRonlinc.org SMITH, S.M.; MEDEIROS, K.C., and TYRRELL, M.C., 2012. Hydrology, herbivory, and the decline of Spartina patens (Aiton) Muhl. in outer Cape Cod salt marshes (Massachusetts, U.S.A.). Joumal of Coastal Research, 28(3) 602-612 West Palm Beach (Florida), ISSN 0749-0208.Salt marsh diehack in different regions of the United States exhibits considerable variability in symptoms, processes, and theoretical or proven causes. On Cape Cod (Massachusetts), where losses within the low-marsh zone (elevations helow mean high tide, dominated hy smooth cordgrass [Spartina alterniflora Loisel.]) have been particularly severe, recent studies suggest that intense grazing pressure from increased ahundances of a native, herhivorous, purple marsh crab (Sesarma reticulatum) is to blame. Low-marsh dieback is spatially heterogeneous because it is closely related to the distrihution of the crahs' preferred suhstrate (peat vs. sand or mud). However, vegetation losses have also occurred in the high marsh, which is comprised of mainly saltmeadow cordgrass {Spartina patens [Aiton] Muhl). In contrast to the low marsh, high-marsh losses consistently occur along the seaward-most edge of this zone, suggesting a link with hydrology (flooding frequency). In this study, we attempted to determine the relative contribution of environmental factors and crab herbivory to high-marsh diehack. To do this, we (1) characterized tidal regimes in dieback vs. healthy areas, (2) assessed the extent of herbivory on S. patens using crab-exclosure cages, (3) documented the ability of S. patens to recover from simulated grazing (chpping) in different marshes and in different areas of individual marshes, and (4) estimated densities of S. reticulatum in two high-marsh diehack areas. The results indicate that S. patens losses are likely the result of a combination of Stressors. Flooding frequency and salinities are higher in dieback areas, which impart a higher level of physiological stress. Plants growing there also seem to have a much-reduced capacity to recover from both simulated and actual grazing hy the herbivorous crab, S. reticulatum. Continued losses of high-marsh vegetation could eliminate this community from coastal wetlands on Cape Cod, Massachusetts. ADDITIONAL INDEX WORDS: Salt marsh, Spartina patens, vegetation loss. Cape Cod.Mean dying = 48% (SE = 5%); mean healthy = 18% (SE = 4%).

East Harbor (Truro, Massachusetts, U.S.A.) is a tidally-restricted salt marsh lagoon that has undergone partial restoration since 2002. After reintroducing seawater to the system following nearly 140 years of impoundment, remarkable transformations in plant and animal communities have occurred. But while a host of marine fish, crustaceans, and benthic invertebrates have become established throughout the system, an important herbivore, common periwinkle (Littorina littorea) has not. This gastropod is absent throughout the open lagoon where in the past several years macroalgae (mainly Enteromorpha intestinalis) has proliferated to nuisance levels. Grazing experiments with common periwinkles suggest that this species could significantly reduce the extent of macroalgae biomass there. The inability of this organism to colonize the lagoon may be related to high water temperatures. Laboratory experiments suggest that 4 days of constant water temperatures ≥ 28°C or 6+ daily hours of 30°C for several days result in high mortality. Data from in situ temperature loggers show that such conditions occur in the lagoon during July-August. Increased tidal flushing could lower water temperatures throughout East Harbor and allow this species to expand its range. This, in turn, could limit the development of macroalgae through herbivory. This study highlights the role of keystone species and the importance of restoring suitable temperature regimes for the functional recovery of hydrologically-impaired systems.

I www.JCRonline.org Smith, S. and Medeiros, K., 2013. Manipulation of water levels to facilitate vegetation cbange in a coastal lagoon undergoing partial tidal restoration (Cape Cod, Massacbusetts) Journal of Coastal Research, 29(6A), 93-99. Coconut Creek (Florida), ISSN 0749-0208.East Harbor is a back-barrier coastal lagoon and salt marsb witbin Cape Cod National Seashore (Massachusetts), wbicb has been undergoing partial tidal restoration since 2002. The current tidal exchange has been sufficient to elevate salinities in tbe open lagoon but is still too constrained by the present infrastructure to create high tides sufficient to flood the peripheral marsh areas. Consequently, an adaptive management strategy using a one-way tide gate was implemented in 2011 that let high tides into the system while blocking tbeir escape. Tbe increased flooding of tbe marsh, above and beyond wbat the current engineering of the system could provide hy opening the restrictive culvert, raised porewater salinities in many areas and resulted in decreases in the cover of freshwater and brackish-water plant taxa-a necessary precursor for the establishment and expansion of native halophytes. This kind of adaptive-management tool can be used to enhance salt marsh restoration in systems tbat can only be partially restored tidally.

Hydrological features on Cape Cod, Massachusetts, USA, include groundwater, freshwater lakes, permanent and seasonal ponds, streams, and estuaries. Rainfall and evaporation/evapotranspiration have long been considered the dominant factors influencing both lake and groundwater levels in this sole-source, unconfined aquifer. However, increases in sea level may also have an effect, especially on this narrow peninsula with a sandy substrate of high permeability. In this study, we analyzed trends between 2000 and 2017 in eleven groundwater wells and nine kettle ponds situated with Cape Cod National Seashore (CCNS). We further explored relationships of these hydrologic variables with local precipitation, temperature and sea level during this period. The results suggest that while precipitation patterns influence seasonal and inter-annual variability, it appears that sea level rise (SLR) may be partially responsible for driving the longer-term trend of rising groundwater levels in several wells. Pond stages did not exhibit any statistically significant trends, and responded more to precipitation during this period of time. Notwithstanding, further acceleration of SLR, along with potential changes in precipitation patterns, can alter the freshwater hydrology of CCNS that may subsequently have biological, chemical, and physical effects throughout these systems.

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