M. Luisa Martínez

The Value of Coastal Wetlands for Hurricane Protection

Abstract Coastal wetlands reduce the damaging effects of hurricanes on coastal communities. A regression model using 34 major US hurricanes since 1980 with the natural log of damage per unit gross domestic product in the hurricane swath as the dependent variable and the natural logs of wind speed and wetland area in the swath as the independent variables was highly significant and explained 60% of the variation in relative damages. A loss of 1 ha of wetland in the model corresponded to an average USD 33 000 (median = USD 5000) increase in storm damage from specific storms. Using this relationship, and taking into account the annual probability of hits by hurricanes of varying intensities, we mapped the annual value of coastal wetlands by 1km × 1km pixel and by state. The annual value ranged from USD 250 to USD 51 000 ha−1 yr−1, with a mean of USD 8240 ha−1 yr−1 (median = USD 3230 ha−1 yr−1) significantly larger than previous estimates. Coastal wetlands in the US were estimated to currently provide USD 23.2 billion yr−1 in storm protection services. Coastal wetlands function as valuable, selfmaintaining “horizontal levees” for storm protection, and also provide a host of other ecosystem services that vertical levees do not. Their restoration and preservation is an extremely cost-effective strategy for society.

Ecological science and sustainability for the 21st century

Through the work of international public health organizations and advancements in the biological and technological sciences, substantial progress has been made in our ability to prevent, control, locally eliminate, and in one case eradicate infectious diseases. Yet each successful control or local elimination has been met with the emergence of new pathogens, the evolution of novel strains, or different epidemiological circumstances that have limited or reversed control methods. To respond to the increasing threat of emerging infectious diseases and bioterrorism it is vital that we design and implement efficient programs that prevent and control infectious pathogen transmission. The theoretical tools of ecology and epidemiology may be the cornerstone in constructing future programs aimed at preventing and controlling infectious diseases throughout the world. Reprinted with permission from Frontiers in Ecology and the Environment, Vol 3, Issue No 1, page 4–11, issue of February 2005. Copyright

Spatial and temporal variability during primary succession on tropical coastal sand dunes

Abstract. We studied primary succession on mobile tropical coastal sand dunes over an 8-yr period. Every six months, we monitored changes in species composition and sand movement in permanent quadrats located on the windward slopes, the arms and the crests. Our results indicate that sand movement decreased over time but was significantly higher on the slopes and crests than on the arms. In all cases, there were seasonal fluctuations in sand movement which increased during the period with strong northerly winds and decreased during the rainy season. Sand movement was significantly correlated with species distribution. Plant cover and species richness increased at all three locations. Diversity increased on the slope, decreased on the arms and remained unchanged on the crest. However, the equitability values indicated the dominance of a few species, especially at the end of the study period. Temporal trends and species turnover rates differed among locations. Species turnover occurred first on the arms (1994), then on the crests (1998) and lastly on the slopes (at the end of the study period). In all cases the tall grass, Schizachyrium scoparium var. littoralis, became dominant over the endemic legume, Chamaecrista chamaecristoides var. chamaecristoides. Similar to temperate dunes, primary succession on tropical sand dunes was spatially and temporally heterogeneous.

Salt Marsh Zonal Migration and Ecosystem Service Change in Response to Global Sea Level Rise: A Case Study from an Urban Region

Coastal wetland plants are expected to respond to global sea level rise by migrating toward higher elevations. Housing, infrastructure, and other anthropogenic modifications are expected to limit the space available for this potential migration. Here, we explore the ecological and economic effects of projected Intergovernmental Panel on Climate Change (IPCC) 2007 report sea level changes at the plant community scale using the highest horizontal (1 m) and vertical (0.01 m) resolution data available, using a 6 x 6 km area as an example. Our findings show that salt marshes do not always lose land with increasing rates of sea level rise. We found that the lower bound of the IPCC 2007 potential rise (0.18 m by 2095) actually increased the total marsh area. This low rise scenario resulted in a net gain in ecosystem service values on public property, whereas market-based economic losses were predicted for private property. The upper rise scenario (0.59 m by 2095) resulted in both public and private economic losses for this same area. Our work highlights the trade-offs between public and privately held value under the various IPCC 2007 climate change scenarios. We conclude that as wetlands migrate inland into urbanized regions, their survival is likely to be dependent on the rate of return on property and housing investments.

Assessment of coastal dune vulnerability to natural and anthropogenic disturbances along the Gulf of Mexico

Human population density is globally three times higher along the coasts than inland, and thus environmental impacts of human activities are greater in magnitude on coastal ecosystems such as beaches and dunes. Vulnerability assessment (the loss of capacity to return to the original dynamic state after system displacement) is thus necessary to evaluate the conservation status and determine the most relevant disturbance events. Twenty-six sites along 902 km of Gulf of Mexico coastline, varying in conservation status and sedimentary dynamics, were sampled. At each site a vulnerability index (VI) was calculated based on variables that described geomorphological condition, marine influence, aeolian influence, vegetation condition and human effects. Vulnerability was very variable along the coast and only 19% of the sampled locations (mostly in the central Gulf of Mexico) displayed low vulnerability. Cluster analyses of the values assigned to the checklists for each location grouped the studied sites into three, according to their VI values. Low vulnerability locations had abundant sediment supply and low human impact. Locations with medium to high VI were mostly affected by their natural geomorphological and marine features and had medium to intense human activities. Management strategies should consider the observed variability in vulnerability, the natural dynamics of these systems and the role of human activities and interests, in order to achieve adequate policies and establish well-informed priorities for integrated coastal zone management.

7 – Disturbance Processes and Dynamics in Coastal Dunes

Coastal dunes occur throughout the world and thus in a diversity of climatic regimes. However, independent of the geographical location, they all share a set of environmental characteristics that greatly affect seed germination, seedling establishment, and adult performance. Repeatedly, and for a wide variety of locations ranging from tropical to subarctic latitudes, it has been demonstrated that the predominant factors that have a significant impact on the dynamics of coastal dune vegetation can be divided into two groups—environmental gradients, and recurring disturbances. Typically, salinity, substrate mobility, radiation, and nutrient contents vary following a gradient. Salinity, near surface wind speed, radiation, and substrate mobility decrease inland, while nutrient and biotic pressures increase. In turn, disturbance events occur mostly through wave scarping, water intrusion, substrate erosion, and burial by sand (or snow) and may be gradual or abrupt, and are commonly spatially and temporally variable. The intensity of these events will depend on the orientation of the coast, wind speed, time of year (or season), storm frequency and intensity, tide regime, surf zone-beach type, and perhaps mean sediment size. However, recent perspectives state that disturbances overlay environmental gradients, and their impact is, therefore, influenced by such gradients. In this sense, the relative importance of each depends on the spatial and temporal scale at which each occurs. In particular, transgressive dune fields are largely ignored in current geological, geomorphological, and ecological research and literature, yet they provide many opportunities for fundamental and exciting research.

Environmental Filtering and Plant Functional Types on Mexican Foredunes along the Gulf of Mexico

Abstract: Ecological theory suggests that environmental filtering (the survival or elimination of species in the community in response to environmental constraints) is a key process in the species assemblages of communities. Environmental filters, such as sand movement and soil salinity in coastal dunes and beaches, may result in shared ecological tolerances and functional types, independently of phylogenetic and evolutionary history. In 19 beach—foredune sites located along the coast of the Gulf of Mexico we studied plant functional composition and diversity of vascular plants. Functional groups were determined with a classification analysis. Relative importance values and diversity indices of species and functional groups were compared with ANOVA tests. We distinguished 5 groups: a group of species tolerant to soil salinity and burial, most abundant on accreting beaches; a group of species tolerant only to burial, which were abundant on all coasts; and 3 groups that lacked specific responses to burial and soil salinity and were most abundant on stable and erosive coasts. Accreting foredunes showed the lowest species richness and functional diversity, because only a few species were tolerant to burial and soil salinity. In the foredune environment, sediment dynamics and geomorphological processes act as environmental filters that largely determine the floristic and functional composition of the community.

Barrier Islands: Coupling Anthropogenic Stability with Ecological Sustainability

Abstract Barrier islands provide a host of critical ecosystem services to heavily populated coastal regions of the world, yet they are quite vulnerable to ongoing sea level rise and a potential increase in the frequency and intensity of oceanic storms. These islands are being degraded at an alarming rate, in part because of anthropogenic attempts at stabilization. In this article, we outline a possible sustainability strategy that incorporates the natural degree of substrate instability on these sedimentary landscapes. We recommend placing the focus for managing barrier islands on maintaining ecosystem function and process development rather than emphasizing barrier islands as structural impediments to wave and storm energy.

Present and Future Challenges of Coastal Erosion in Latin America

ABSTRACT Silva, R.; Martínez, M.L.; Hesp, P.; Catalan, P.; Osorio, A. F.; Martell, R.; Fossati, M.; Miot da Silva, G.; Mariño-Tapia, I.; Pereira, P.; Cienfuegos, R.; Klein, A., and Govaere, G., 2014. Present and future challenges of coastal erosion in Latin America. The coastal zones of Latin America have many landforms and environments, including sedimentary cliffs, deeply incised estuaries, headlands, barrier coasts and low lying, muddy coastal plains. These forms will respond differently to the expected changes in climate and associated sea level rise, which may produce coastal erosion in the future. Considering the coasts of Latin America overall, erosion is not yet a serious threat, although it is widespread and it is severe in some parts. Major erosion problems are frequently associated with human intervention in sediment supply, with poor planning or with the morphodynamic nature of the coast. Permanent erosional processes, locally or regionally, are caused by tectonic subsidence, deforestation and the fragmentation of coastal ecosystems, land use changes and sediment deficits because of infrastructure built along the coast. In this article we analyse coastal erosion in Latin America and the challenges it presents to the region. We first highlight the relevance of Latin America in terms of its biodiversity; then we describe the population at risk, demographic trends and economic growth throughout the low lying coastal zones. We also examine the vulnerability of the region by analyzing the resilience of key coastal ecosystems after exposure to the most frequent hazards that affect coastal zones in Latin America, namely tropical cyclones, sea level rise, ocean acidification, earthquakes and tsunamis. Finally, we discuss seven case studies of coastal erosion across Latin America. We close the study by pinpointing the main areas of concern in Latin America and explore possible strategies to overcome erosion and thus sustain economic growth, minimize population risk and maintain biodiversity.

Artificial modifications of the coast in response to the Deepwater Horizon oil spill: Quick solutions or long-term liabilities?

The Deepwater Horizon oil spill threatened many coastal ecosystems in the Gulf of Mexico during the spring and summer of 2010. Mitigation strategies included the construction of barrier sand berms, the restriction or blocking of inlets, and the diversion of freshwater from rivers to the coastal marshes and into the ocean, in order to flush away the oil, on the premise that these measures could reduce the quantity of oil reaching sensitive coastal environments such as wetlands or estuaries. These projects result in changes to the ecosystems that they were intended to protect. Long-term effects include alterations of the hydrological and ecological characteristics of estuaries, changes in sediment transport along the coastal barrier islands, the loss of sand resources, and adverse impacts to benthic and pelagic organisms. Although there are no easy solutions for minimizing the impacts of the Deepwater Horizon disaster on coastal ecosystems, we recommend that federal, state, and local agencies return to the ...