Salt Marsh Cordgrass Spartina Alterniflora Research Articles

Chemically mediated rheotaxis of endangered tri-spine horseshoe crab: potential dispersing mechanism to vegetated nursery habitats along the coast.

An enhanced understanding of larval ecology is fundamental to improve the management of locally depleted horseshoe crab populations in Asia. Recent studies in the northern Beibu Gulf, China demonstrated that nesting sites of Asian horseshoe crabs are typically close to their nursery beaches with high-density juveniles distributed around mangrove, seagrass and other structured habitats. A laboratory Y-maze chamber was used to test whether the dispersal of early-stage juvenile tri-spine horseshoe crab Tachypleus tridentatus is facilitated by chemical cues to approach suitable nursery habitats. The juvenile orientation to either side of the chamber containing controlled seawater or another with various vegetation cues, as well as their movement time, the largest distance and displacement were recorded. The juveniles preferred to orient toward seagrass Halophila beccarii cues when the concentration reached 0.5 g l-1, but ceased at 2 g l-1. The results can be interpreted as a shelter-seeking process to get closer to the preferred settlement habitats. However, the juveniles exhibited avoidance behaviors in the presence of mangrove Avicennia marina and invasive saltmarsh cordgrass Spartina alterniflora at 2 g l-1. The juveniles also spent less time moving in the presence of the A. marina cue, as well as reduced displacement in water containing the S. alterniflora cue at 1 and 2 g l-1. These results may explain the absence of juvenile T. tridentatus within densely vegetated areas, which have generally higher organic matter and hydrogen sulfide. Early-stage juvenile T. tridentatus are capable of detecting and responding to habitat chemical cues, which can help guide them to high-quality settlement habitats. Preserving and restoring seagrass beds in the intertidal areas should be prioritized when formulating habitat conservation and management initiatives for the declining horseshoe crab populations.

Submergence, nutrient enrichment, and tropical storm impacts on Spartina alterniflora in the microtidal northern Gulf of Mexico

Salt marshes face chronic anthropogenic impacts such as relative sea level rise and eutrophication, as well as acute disturbances from tropical storms that can affect the productivity of these important communities. However, it is not well understood how marshes already subjected to eutrophication and sea level rise will respond to added effects of episodic storms such as hurricanes. We examined the interactive effects of nutrient addition, sea level rise, and a hurricane on the growth, biomass accumulation, and resilience of the saltmarsh cordgrass Spartina alterniflora in the Gulf of Mexico. In a microtidal marsh, we manipulated nutrient levels and submergence using marsh organs in which cordgrasses were planted at differing intertidal elevations and measured the impacts of Hurricane Isaac, which occurred during the experiment. Prior to the hurricane, grasses at intermediate and high elevations increased in abundance. After the hurricane, all treatments lost approximately 50% of their shoots, demonstrating that added nutrients and elevation did not provide resistance to hurricane disturbance. At the end of the experiment, only the highest elevations had been resilient to the hurricane, with increased above- and belowground growth. Added nutrients provided a modest increase in above- and belowground growth, but only at the highest elevations, suggesting that only elevation will enhance resilience to hurricane disturbance. These results empirically demonstrate that S. alterniflora in microtidal locations already subjected to submergence stress is less able to recover from storm disturbance and suggests we may be underestimating the loss of northern Gulf Coast marshes due to relative sea level rise.

Ribbed mussel (Geukensia demissa) filtration services are driven by seasonal temperature and site-specific seston variability

Ribbed mussels (Geukensia demissa) are ubiquitous intertidal invertebrates of eastern North American salt marshes, often living in close association with salt marsh cordgrass Spartina alterniflora. They are typically concentrated at the lower extent of the vegetated zone along tidal channels, but are also found across the marsh platform. As filter-feeding bivalves, ribbed mussels remove suspended micro-particulate matter and associated nutrients from the water column, potentially resulting in benefits to water quality. However, the magnitude of such ecosystem services may depend on temporal and spatial variation in the mussel's water clearance and particle filtration rates. The goal of this study was to identify sources of variation regarding the distribution of ribbed mussel filtration services.Seasonal-spring, summer, and fall- water clearance and particle filtration rates were quantified for ribbed mussels collected from three habitats- low marsh along main tidal channels; low marsh along intra-marsh creek networks; and from the high marsh- and replicated in four representative marshes- three in New Jersey and one in Rhode Island, USA, normalized by mussel dry tissue biomass. Clearance rates varied with seasonal temperatures, but exhibited low spatial variability among habitats and marshes, highlighting the importance of understanding the temporal physiological variability when calculating annual rates. In contrast, filtration rates were highly variable, driven largely by spatial variation in seston availability. Annual bulk filtration services provided by ribbed mussels are therefore largely driven by both temporal variability in water processing and spatial variations in food availability, and can therefore be predicted by integrating seasonal clearance rates and site-specific seston composition.

Increased primary production shifts the structure and composition of a terrestrial arthropod community

Numerous studies have examined relationships between primary production and biodiversity at higher trophic levels. However, altered production in plant communities is often tightly linked with concomitant shifts in diversity and composition, and most studies have not disentangled the direct effects of production on consumers. Furthermore, when studies do examine the effects of plant production on animals in terrestrial systems, they are primarily confined to a subset of taxonomic or functional groups instead of investigating the responses of the entire community. Using natural monocultures of the salt marsh cordgrass Spartina alterniflora, we were able to examine the impacts of increased plant production, independent of changes in plant composition and/or diversity, on the trophic structure, composition, and diversity of the entire arthropod community. If arthropod species richness increased with greater plant production, we predicted that it would be driven by: (1) an increase in the number of rare species, and/or (2) an increase in arthropod abundance. Our results largely supported our predictions: species richness of herbivores, detritivores, predators, and parasitoids increased monotonically with increasing levels of plant production, and the diversity of rare species also increased with plant production. However, rare species that accounted for this difference were predators, parasitoids, and detritivores, not herbivores. Herbivore species richness could be simply explained by the relationship between abundance and diversity. Using nonmetric multidimensional scaling (NMDS) and analysis of similarity (ANOSIM), we also found significant changes in arthropod species composition with increasing levels of production. Our findings have important implications in the intertidal salt marsh, where human activities have increased nitrogen runoff into the marsh, and demonstrate that such nitrogen inputs cascade to affect community structure, diversity, and abundance in higher trophic levels.

Modeling epiphytic community production

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 387:61-70 (2009) - DOI: https://doi.org/10.3354/meps08101 Modeling epiphytic community production Gabriella Jackson1,5,*, Richard G. Zingmark1,2,3, Alan J. Lewitus3,4,6 1Marine Science Program, 2Department of Biological Sciences and 3Belle Baruch Institute, University of South Carolina, Columbia, South Carolina 29208, USA 4Hollings Marine Laboratory, Department of Natural Resources, 331 Ft. Johnson Road, Charleston, South Carolina 29412, USA 5Present address: Department of Biological Sciences, Central Washington University, Ellensburg, Washington 98926, USA 6Present address: NOAA, Center for Sponsored Coastal Ocean Research, Silver Spring, Maryland 20910, USA *Email: jackson@cwu.edu ABSTRACT: Mathematical models were used to quantify annual production of the epiphytic community on the saltmarsh cordgrass Spartina alterniflora. Hourly measurements of solar radiation and light attenuation (a function of plant canopy and tidal height) were used as forcing functions in the model. Steeper initial slopes (α) of photosynthesis vs. irradiance curves (P-I curves) were estimated in the summer (when the canopy was densest), indicating highest shade adaptation. Model validation showed a good agreement between actual hourly production measurements and hourly predicted net production (r2 = 0.90). Predicted areal epiphytic community production was negative during all seasons and higher in the high marsh (short S. alterniflora zone) than in the low marsh (tall S. alterniflora zone), due to a more open canopy and less exposure to tidal waters. The results indicated that the epiphytic community on S. alterniflora in North Inlet is an energy sink (i.e. net heterotrophic community). When irradiance values were held constant at 615 µmol photons m–2 s–1 (mean daily irradiance value during daylight), production values were overestimated by 11.68 to 34.77%. Therefore, building quantitative models that include hourly changes in light is key to the realistic estimation of epiphytic production in salt marshes. KEY WORDS: Epiphytic community production · Mathematical modeling · P-I curves · Salt marsh · Spartina alterniflora Full text in pdf format PreviousNextCite this article as: Jackson G, Zingmark RG, Lewitus AJ (2009) Modeling epiphytic community production. Mar Ecol Prog Ser 387:61-70. https://doi.org/10.3354/meps08101 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 387. Online publication date: July 28, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

A specialist detritivore links Spartina alterniflora to salt marsh food webs

Because most plant production is subject to senescence and is eventually consumed by detritivores, the factors that drive detritivore diet choice are pivotal to the flow of energy and materi- als through food webs. Here, we investigated the common salt marsh amphipod Gammarus palustris, which is a habitat specialist that feeds specifically on the dead leaves of its living host plant, salt marsh cordgrass Spartina alterniflora. Restricted use and consumption of dead S. alterniflora was reinforced by superior amphipod performance (survival, size, and sexual development) on dead S. alterniflora relative to other diets, and was driven at least in part by amphipods being physically able to feed on soft, decaying plant tissues but not live, turgid tissues. Stable isotopes from field surveys and laboratory assimilation assays suggest that amphipods also feed on S. alterniflora in the field, and that the important marsh fish Fundulus hetroclitus feeds on amphipods. Thus, consumption of G. palustris by F. heteroclitus may be an important trophic pathway linking cordgrass production to nearshore food webs. Importantly, direct isotopic analyses of amphipods and their known food sources demonstrated substantial deviation of observed fractionation factors from idealized stan- dards. This suggests caution when using idealized trophic shifts to describe food web linkages, and a renewed focus on assimilation assays to determine the realized fractionation of dietary isotopes.

Effects of dimethylsulfoniopropionate (DMSP) produced by the cordgrass Spartina alterniflora on its epiphytic algal community

A range of marine algae produce dimethylsulfoniopropionate (DMSP), but only a few species of higher plants, such as the salt marsh cordgrass Spartina alterniflora, are capable of producing this compound. However, its ecophysiological function in S. alterniflora has not been fully established yet. Our hypothesis for this study was thatDMSPacts as an antifouling agent. The epiphytic algal biomass along dead S. alterniflora stem sections (seven 15 cm-sections from the bottom-most to the upper-most part of the plant) was overall higher than on stem sections of living plants (t-test, P ≤ 0.04, α=0.05). Although an inverse relationship between DMSP concentrations and epiphytic algal biomass was found along the stem height of living S. alterniflora, experiments showed that increasing DMSP concentrations (0 – 30 μM) did not inhibit epiphytic respiration (t-test, 0.255<P<0.603, α=0.05) and production (t-test, 0.198<P<0.949, α=0.05). Dimethylsulfonioacetate (DMSA, a chemical compound structurally similar to DMSP) and acrylic acid (AA, one of the degradation products of DMSP) were also tested but did not affect epiphytic algal production either. This study was not able to elucidate the role of DMSP in S. alterniflora, but it ruled out its effect as an antifouling agent.

Effects of chemical cues on settlement behavior of blue crab Callinectes sapidus postlarvae

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 154:143-153 (1997) - doi:10.3354/meps154143 Effects of chemical cues on settlement behavior of blue crab Callinectes sapidus postlarvae Welch JM, Rittschof D, Bullock TM, Forward RB Jr Settlement of blue crab Callinectes sapidus Rathbun postlarvae (megalopae) was examined in the field in the presence and absence of chemical cues from settlement habitats and potential megalopal predators. Megalopae in premolt preferentially settled on collectors containing seagrasses Zostera marina and Halodule wrightii, but not on collectors with salt marsh cordgrass Spartina alterniflora. Settlement of megalopae was reduced by up to 40% in the presence of predators from several different habitats, including crabs Uca pugilator, U. pugnax and Panopeus herbstii, and grass shrimp Palaemonetes pugio. Laboratory predation assays showed that each of these potential predators ate C. sapidus megalopae if they encountered them. Megalopae avoided odors of U. pugilator in chemotaxis assays, and showed no reaction to odors from Z. marina and S. alterniflora. Settlement of megalopae was unaffected by the presence of adult C. sapidus or brown shrimp Penaeus aztecus, neither of which consumed megalopae in laboratory predation assays. Megalopae showed no reaction to fouled shells of oyster Crassostrea virginica, but avoided live C. virginica. Thus, settling blue crab megalopae can distinguish among settlement sites using chemical cues, and their discrimination ability increases in the premolt stage. Chemical cues · Settlement site selection · Callinectes sapidus · Megalopae · Post-<\n>larvae · Eelgrass · Predators · Chemotaxis · Blue crab Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 154. Publication date: July 31, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.

Early diagenesis of lignin-associated phenolics in the salt marsh grass Spartina alterniflora

The predepositional stability of lignin in the salt marsh cordgrass Spartina alterniflora was examined in two different degradation studies: one was a traditional litterbag study carried out using post-senescent brown leaves in a North Carolina marsh creek, and the other was a study in which senescing, standing plants were tagged and allowed to undergo in situ degradation in a Sapelo Island, Georgia, salt marsh. Based on results from lignin oxidation product (LOP) analysis of leaves, lignin in the S. alterniflora was shown to be significantly degraded in both studies, with 13 ± 2% and 25 ± 12% of the total lignin mass loss occurring over the 496-day litterbag and 146-day tagged studies, respectively. A comparison of the results from both studies suggests that most of the calculated lignin loss (> 90%) occurs early in the degradation history of the plant, with a significant portion occurring while the plant is still standing in the salt marsh. Further detailed evaluation of this loss demonstrates that selective lignin degradation occurs in S. alterniflora, deriving from the preferential loss of labile lignin moieties. The most labile component, trans-ferulic acid, accounted for 57% and 82% of the total lignin loss in the litterbag and tagged studies, respectively, based on normalization to syringyl-phenol concentrations. Comparison of these two data sets supports the following approximate lignin stability sequence for S. alterniflora: S ≅ Ca ≅ V > P > Fa. Based on measured changes in both the lignin mass loss and the LOP acid/aldehyde ratio, as well as evidence suggesting that degradation occurred under oxic conditions, it is proposed that aromatic ring cleavage was the predominant mechanism of lignin degradation in both studies. In light of these results and those from other recent lignin degradation studies, we discuss the geochemical consequences regarding the usefulness of lignin oxidation products as quantitative tracers of vascular plant-derived organic matter being transported, deposited, and buried in aquatic environments.

The excretion of heavy metals by the salt marsh cord grass, Spartina alterniflora, and Spartina's role in mercury cycling

Excreted salts and leaves from the Salt Marsh Cordgrass Spartina alterniflora were collected from two different sites. One site, Piles Creek (PC), is near heavily industrialized Linden, New Jersey, USA. The other site, Big Sheepshead Creek (BSC), is located near non-industrialized Tuckerton, New Jersey, USA. PC soil concentrations of mercury were 18·17 ± 7·67 ppm, while BSC soil concentrations were 0·22 ± 0·04 ppm. Spartina leaves from PC contained 0·16 ± 0·07 ppm of mercury, and BSC leaves contained 0·02 ± 0·0 ppm. Laboratory studies showed that S. alterniflora from both sites was capable of excreting mercury. Field collected salts from PC Spartina plants contained 0·11 ± 0·02 ppm of mercury, 2·60 ± 0·52 ppm of cadmium and 11·98 ± 0·94 ppm of zinc. These levels of heavy metals were as much as five- and-a-half times the concentrations of these metals found in ambient sea salts.

Uptake of Dissolved Sulfide by Spartina alterniflora : Evidence from Natural Sulfur Isotope Abundance Ratios

The difference in the stable sulfur isotope ratios of sulfate and sulfide in marsh pore water was used to verify the uptake of hydrogen sulfide by the salt marsh cordgrass Spartina alterniflora in a North Carolina salt marsh. Most of the plant sulfur derived from pore-water sulfide was recovered as sulfate, an indication that the sulfide had been oxidized within the plant. The analysis of the sulfur isotope ratios of other coastal halophytes may be a useful technique for determining whether sulfide is taken up by plants in saline wetlands.

The influence of soil drainage on the growth of salt marsh cordgrass Spartina alterniflora in North Carolina

The occurrence of the height forms of Spartina alterniflora was directly related to marsh soil drainage and aeration in a natural salt marsh in North Carolina. Linear regression analysis indicated that differential soil drainage among the height forms accounted for 70% of the variation in plant height. Total biomass of tall and medium Spartina and the aerial standing crop of short Spartina were significantly reduced when soil drainage was experimentally impaired in the field. When the degree of soil drainage was manipulated in greenhouse experiments under low nutrient regimes, biomass production of tall and medium Spartina was greatest when the soil-root system was undrained. Short Spartina was relatively unaffected by the soil drainage treatment. In phytotron greenhouse experiments under high nutrient regimes, the biomass of tall Spartina transplants also increased as soil drainage decreased; however, stagnant conditions (water level constant at 5 cm above the pot-soil surface) resulted in the least growth.