Kennedy A.B.,University of Notre Dame |
Gravois U.,University of Florida |
Zachry B.,Texas Tech University |
Luettich R.,UNC CH Institute of Marine science |
And 5 more authors.
Continental Shelf Research | Year: 2010
Hurricanes can produce extreme nearshore waves and surge, but permanent gauging stations are often much sparser than is desired. This paper describes the rationale behind and outline for rapidly installed temporary coastal gauges, and presents results during Hurricane Gustav (2008). Within 48. h prior to landfall, twenty self-recording pressure gauges were deployed in depths of 1.4-23. m over more than 700. km of coastline, using helicopters to cover the large distances. Results showed a complex picture that was strongly dependent on location. East of the Mississippi Delta, open coast waves were large, and surge reached 3.8. m NAVD88 in marshes. West of the delta but near landfall, waves and surge were generally smaller as the river levees blocked flow from East to West. West of landfall, both waves and surge were very small and the most prominent feature was a water level drawdown that reached 1.5. m. Wave spectra varied strongly depending both on location and time from landfall. This type of rapid gauging program is straightforward to duplicate: with multiple localized deployment centers to ensure coverage, dense nearshore hurricane wave and surge records could increase substantially in the future. © 2010 Elsevier Ltd.
Piehler M.F.,UNC CH Institute of Marine science |
Currin C.A.,National Oceanic and Atmospheric Administration |
Hall N.S.,UNC CH Institute of Marine science
Journal of Experimental Marine Biology and Ecology | Year: 2010
Benthic microalgal communities are important components of estuarine food webs and make substantial contributions to coastal materials cycling. Nitrogen is generally the limiting factor for marine primary production; however other factors can limit benthic primary producers because of their access to the additional nutrients found in sediment porewater. Field and laboratory experiments were conducted to test the hypothesis that water column nitrogen supply affects estuarine sandflat benthic microalgal community structure and function. Our field and mesocosm experiments assessed changes at both the population and functional group levels. Simulated water column nitrogen additions increased maximum community photosynthesis in most cases (Pbmax from photosynthesis vs. irradiance curves). Additional changes that resulted from nitrogen additions were decreases in porewater phosphate, increases in porewater ammonium, shifts in community composition from N2 fixing cyanobacteria toward diatoms, and detectable, though not statistically significant increases in biomass (as chlorophyll a). Results from field and laboratory experiments were quite similar, suggesting that laboratory experiments support accurate predictions of the response of intertidal benthic microalgae to changes in water column nutrient conditions. © 2010 Elsevier B.V. All rights reserved.
Paerl H.W.,UNC CH Institute of Marine science |
Hall N.S.,UNC CH Institute of Marine science |
Peierls B.L.,UNC CH Institute of Marine science |
Rossignol K.L.,UNC CH Institute of Marine science
Estuaries and Coasts | Year: 2014
Coastal watersheds support more than one half of the world's human population and are experiencing unprecedented urban, agricultural, and industrial expansion. The freshwater-marine continua draining these watersheds are impacted increasingly by nutrient inputs and resultant eutrophication, including symptomatic harmful algal blooms, hypoxia, finfish and shellfish kills, and loss of higher plant and animal habitat. In addressing nutrient input reductions to stem and reverse eutrophication, phosphorus (P) has received priority traditionally in upstream freshwater regions, while controlling nitrogen (N) inputs has been the focus of management strategies in estuarine and coastal waters. However, freshwater, brackish, and full-salinity components of this continuum are connected structurally and functionally. Intensification of human activities has caused imbalances in N and P loading, altering nutrient limitation characteristics and complicating successful eutrophication control along the continuum. Several recent examples indicate the need for dual N and P input constraints as the only nutrient management option effective for long-term eutrophication control. Climatic changes increase variability in freshwater discharge with more severe storms and intense droughts and interact closely with nutrient inputs to modulate the magnitude and relative proportions of N and P loading. The effects of these interactions on phytoplankton production and composition were examined in two neighboring North Carolina lagoonal estuaries, the New River and Neuse River Estuaries, which are experiencing concurrent eutrophication and climatically driven hydrologic variability. Efforts aimed at stemming estuarine and coastal eutrophication in these and other similarly impacted estuarine systems should focus on establishing N and P input thresholds that take into account effects of hydrologic variability, so that eutrophication and harmful algal blooms can be controlled over a range of current and predicted climate change scenarios. © 2014 Coastal and Estuarine Research Federation.