Hurricane Induced Land and Vegetation Changes in the Breton Sound Estuary and Chandeleur Islands Using Landsat 5 TM

This study focuses on hurricane-induced changes in land and vegetation primarily in two study areas, the Breton Sound Estuary and the Chandeleur Islands, southeast of New Orleans, Louisiana. Breton Sound Estuary consists of the Caernarvon Diversion, a fresh water diversion of the Mississippi River that supplies this region with managed pulses of fresh water and sediments. The Chandeleur Islands are a chain of barrier islands that are uninhabited and transgressive in nature. A sequence of hurricanes in the past two decades has greatly altered both areas significantly. Satellite data were analyzed for a period of 24 years (1987-2011) of Breton Sound Estuary region and for 14 years (1997-2010) of the Chandeleur Islands. Landsat 5 Thematic Mapper data were used to classify and analyze changes using ERDAS IMAGINE 9.3 software. Images were classified into land and water classes using a hybrid classification technique that is unlike the techniques used in the past. Quantitative spatial analyses of the extent of land loss, vegetation changes and beach loss/gain over time were performed. Three change detection techniques were used in this research, which include post-classification spatial intersection, Change Vector Analysis (CVA) and image differencing. Maximum land loss in the Breton Sound Estuary region was due to Hurricane Katrina in 2005 when 196 km2 of land was converted to water from November 2004 to October 2005. Marsh area loss in the 24-year time series coincided with the overall land area loss. An increase in marsh area was detected in three segments of the time series i.e. 1987 to 1991, 1992 (after Hurricane Andrew) to 2003 (before Hurricane Ivan) and 2006 (after Hurricane Katrina) to 2010 indicating some recovery between hurricane years. At the Chandeleur Islands, most of the land loss over the past decade was due to four major hurricanes since 1997; Hurricane Georges in 1998, Hurricane Ivan in 2004, Hurricane Katrina in 2005 and Hurricane Gustav in 2008. The most significant hurricane that impacted these islands was Hurricane Georges in 1998 that resulted in a land loss of 76.5% measured from 1997. The land area increase after the impact of Hurricane Gustav in 2008 to 2011 was very low ranging from 0 km2 to 2 km2. Shoreline change detection results indicated that the barrier islands moved westward (landward), a maximum of 1.7 km in the southern section. Seven kilometres of the linear coastline was lost in the northern tip and 15 km in the southern tip. The change detection analysis and the shoreline change analysis indicated that the southern section of these islands has undergone greater damage due to erosion than the northern section

Genomic and physiological footprint of the Deepwater Horizon oil spill on resident marsh fishes

The biological consequences of the Deepwater Horizon oil spill are unknown, especially for resident organisms. Here, we report results from a field study tracking the effects of contaminating oil across space and time in resident killifish during the first 4 mo of the spill event. Remote sensing and analytical chemistry identified exposures, which were linked to effects in fish characterized by genome expression and associated gill immunohistochemistry, despite very low concentrations of hydrocarbons remaining in water and tissues. Divergence in genome expression coincides with contaminating oil and is consistent with genome responses that are predictive of exposure to hydrocarbon-like chemicals and indicative of physiological and reproductive impairment. Oil-contaminated waters are also associated with aberrant protein expression in gill tissues of larval and adult fish. These data suggest that heavily weathered crude oil from the spill imparts significant biological impacts in sensitive Louisiana marshes, some of which remain for over 2 mo following initial exposures

Changes in protein expression associated with chronic in vitro exposure of hexavalent chromium to osteoblasts and monocytes: a proteomic approach

Cr (VI) is a well-recognized environmental toxin and carcinogen. It is known to be released from orthopedic metal implants in-situ by biocorrosion and is speculated to play a role in periprosthetic osteolysis. It is hence essential to understand its long-term biological effects. We have assessed the in vitro responses of osteoblasts and monocytes to chronic exposure (3 weeks) to Cr (VI), at concentrations that have been measured in patients with metal implants, using two-dimensional gel electrophoresis. Cr (VI) exposure resulted in a differential time-dependent regulation of glycolytic, stress, and cytoskeletal proteins. The proteins that have been found to be altered in expression play an essential role in normal cellular functioning such as energy metabolism, cell signaling, and proliferation. The results highlight the complex molecular changes that occur in both cell types with long-term exposure to Cr and may be useful in establishing a series of clinically useful biomarkers to monitor long-term use of metallic implants