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Coastal & Estuarine Science News (CESN) is an electronic publication providing brief summaries of select articles from the journal Estuaries & Coasts that emphasize management applications of scientific findings. It is a free electronic newsletter delivered to subscribers on a bimonthly basis.

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2013 August


Vocabulary Lesson: A Proposal for Defining “Coastal” Populations
What to Plant? Using Data to Plan Dune Restoration Projects
Is Development Along Tidal Creeks Hazardous to Ecological and Human Health?
Confluence of Factors Leads to Possible “Tipping Point” for Eutrophication in Maryland Coastal Bays

Vocabulary Lesson: A Proposal for Defining “Coastal” Populations

How many people live by the coast? We’ve gotten pretty good at counting people in the U.S., but this seemingly straightforward question is actually not simple to answer. There are several methods currently in use to determine what constitutes a “coastal” population, depending on the definition of “coast” and why you want the data in the first place. For example, the U.S. Census, FEMA, and NOAA all have different methods for reporting the size of coastal populations in shoreline-adjacent counties. This lack of standardization can cause confusion, particularly when the wrong data are applied to a given management problem.

The authors of a recent article in Estuaries and Coasts propose a simple approach for generating and applying coastal population statistics at the national and regional level. Their framework addresses two components of coastal populations: the population most directly affected by the coast (for example, those that bear the greatest risk from coastal hazards and benefit the most from coastal economic activities like fishing) and the population that most directly affects the coast (where land use and anthropogenic water quality changes most directly impact coastal ecosystems). After evaluating a number of sets of shoreline-adjacent counties, the authors conclude that the population most directly affected by the coast should be calculated from the FEMA shoreline-adjacent county suite, which has the minimum geographic footprint and the fewest geographic gaps. Thirty-nine percent of the nation’s population lives in these 452 counties, which represent less than 10% of the nation’s land area, excluding Alaska. To determine the population that most directly affects the coast, the authors recommend using the permanent population of coastal watershed counties as defined by NOAA’s Coastal Assessment Framework. Based on 2010 data, the authors estimate that 52% of the U.S. population lives in these 769 counties, which represent less than 20% of the nation’s land area, excluding Alaska. Use of these standard definitions will increase consistency in coastal policy discussions and improve public understanding of coastal issues.

Source: Ache, B. W., K. M. Crossett, P. A. Pacheco, J. E. Adkins, and P. C. Wiley. 2013. “The Coast” is complicated: A model to consistently describe the nation’s coastal population. Estuaries and Coasts 36 (June 2013). DOI: 10.1007/s12237-013-9629-9.

 What to Plant? Using Data to Plan Dune Restoration Projects

Every gardener understands that what you plant and where you plant it has a huge impact on your garden’s yield. Authors of a recent study using a long-term data set to determine the best plants to use in dune restoration projects would agree, and would add that the answer depends on your long- and short-term management goals.

The authors examined ten years of monitoring data to characterize the persistence and storm-resistance of various plant species in different dune zones on St. George Island, FL. Luckily, or unluckily, several major storms blew through the area in the ten years of data collection, so the authors were able to determine how storm activity changed the vegetative communities in the dunes. That characterization was then used to predict which species would have the highest potential for survival and growth as restoration candidates in damaged dune areas. The predictions were tested by transplanting six species into three dune zones (foredune, interdune, backdune) and comparing their survival and growth over two years. Results varied significantly with species and dune zone. All six species had similar overall survival rates in the inter- and backdune zones, while transplant survival in the foredune was generally lower. Uniola paniculata (sea oats) was found to be a particularly good candidate for restoration projects across all dune zones, whereas Muhlenbergia capillaris (hairgrass) and Schizachyrium maritimum (bluestem) would work better in the interdune and backdune. Centella asiatica (spadeleaf) had the lowest survival of the six species. In some cases, a species had high survival and growth in a given dune zone but showed more storm resistance in a different zone, and outcomes sometimes changed depending on how long after transplantation measurements were taken. Interestingly, transplant success did not always match the natural occurrences or abundances of that species, nor the storm resistance of that species as determined by the initial data analysis.

The authors conclude that ecological data should be considered when planning restoration projects, but they also point out that, ideally, trial studies of candidate species should be undertaken with each project.

Source: Gornish, E. S. and T. E. Miller. 2013. Using long-term census data to inform restoration methods for coastal dune vegetation. Estuaries and Coasts 36 (June 2013). DOI: 10.1007/s12237-013-9617-0.

 Is Development Along Tidal Creeks Hazardous to Ecological and Human Health?

In the southeastern U.S., tidal creeks and marshes are becoming increasingly popular spots for development. But a range of studies in recent years has provided evidence that human encroachment can degrade water and habitat quality in these critical ecosystems. A recent large-scale study of 19 tidal creek watersheds in North Carolina, South Carolina, and Georgia suggests that our desire for a water view could indirectly lead not only to ecological degradation, but also to human health impacts like enhanced pathogen and toxin loading and increased flooding.

The authors determined relationships among measures of coastal development in creek watersheds, ecological condition of tidal creeks, and potential impacts to human populations. Results indicated that increased development in a given watershed (represented by percent impervious surface) is correlated with increases in some nutrient loadings, concentrations of toxic chemicals in sediments, increased likelihood of flooding, higher concentrations of microbial indicators of fecal contamination in the water column, and increased incidence of high concentrations of coliphages and coliform bacteria in oyster flesh. In general, headwater branches of the creeks were more susceptible to degradation than downstream branches, demonstrating that these upstream areas could represent an early warning system for the threat of degradation downstream and in coastal areas. The authors also refined and added to an existing conceptual model of anthropogenic impacts on tidal creek ecosystems. They note that the scale of their study (hundreds to thousands of hectares) is also the scale at which coastal land use decisions are typically made, providing coastal managers with a valuable framework for addressing these stressors.

Source: Sanger, D., A. Blair, G. DiDonato, T. Washburn, S. Jones, G.  Riekerk, E. Wirth, J. Stewart, D. White, L. Vandiver, and A. F.  Holland. 2013. Impacts of coastal development on the ecology of tidal creek ecosystems of the US southeast including consequences to humans. Estuaries and Coasts 36(June 2013). DOI: 10.1007/s12237-013-9635-y.

 Confluence of Factors Leads to Possible “Tipping Point” for Eutrophication in Maryland Coastal Bays

Long term monitoring in the Maryland Coastal Bays has indicated that water quality in these coastal lagoons has been declining for many years, particularly with respect to nutrient loading. Unfortunately, in the early 2000s the news seemed to get even worse: within a few years, water quality suddenly started to decline even faster following a shift from long-term dry to long-term wet conditions. A team of researchers examined regional trends in water quality parameters in the bays in order to determine the factors that might be responsible for this shift, which could represent a new stable state for this system. They used a statistical approach called analysis of cumulative sums of variability, or CUSUM, to understand patterns of long-term change.

Their results demonstrate that concentrations of some nutrients, NH4+ and PO43- in particular, climbed significantly faster than previous years during 2001 - 2003, as did chl a and some algal blooms; conversely, SAV beds declined. Phytoplankton communities also shifted such that incidence of brown tide events has leveled off regionally, but blooms of picocyanobacteria have increased. Further analysis revealed that this suite of changes could be attributable to a shift in average rainfall during the early 2000s superimposed on steadily increasing anthropogenic and agricultural nutrient inputs and associated biogeochemical responses. The authors advise that the retentive nature of these coastal lagoons combined with their reducing environment will make these changes difficult to reverse if current nutrient management practices are not accelerated.

Source: Glibert, P. M., D. C. Hinkle, B. Sturgis, and R. V. Jesien. 2013. Eutrophication of a Maryland/Virginia coastal lagoon: a tipping point, ecosystem changes, and potential causes. Estuaries and Coasts 36 (June 2013). DOI: 10.1007/s12237-013-9630-3.