Disturbance and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill

Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Sampling occurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littoraria snails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy

An Overview of 9/11 Experiences and Respiratory and Mental Health Conditions among World Trade Center Health Registry Enrollees

http://deepblue.lib.umich.edu/bitstream/2027.42/61276/1/farfel m, digrande l, brackbill r, galea s, overview of 9-11 experiences and respiratory and mental haelth conditions.pd

Response of Pinus taeda L to soil flooding and salinity

Seedlings of Pinus taeda L were subjected to soil flooding alone (F) and combined with salinity (FS) of 50 mol m-3. The flooding effects on soil were quantified by measuring soil redox potential. Soil redox potential remained in the range of +400 to +450 mV in control pots while it was reduced to -50 to -140 mV in flooded pots. Stomatal conductance (g) and net carbon assimilation (A) were reduced significantly under flooding alone and flood/salt combination treatments. Stomatal conductance averaged 120 mmol H 2O m-2 s-1 for control plants, while it averaged 51 and 45 mmol H2O m-2 s-1 for flooded (F) and flooded plus salt (FS) treatments, respectively. Net carbon assimilation was reduced from 5.82 μmol CO 2 m-2 s-1 (control plants) to 2.22 and 0.09 μmol CO2 m-2s-1 in F and FS plants, respectively. The reductions in g and A were statistically significant. Dry weight increment per plant was reduced from 24.38 g in control to 10.09 and 8.22 g per plant in F and FS treatments, respectively. The reduction represents 59% reduction in F and 66% reduction in FS treatment. Based on the present results, it is concluded that : 1), P taeda showed considerable sensitivity to saltwater treatment within the range of soil anaerobiosis and salinity tested; and 2), in areas where saltwater intrusion occurs frequently, regeneration and survival of this species will be adversely affected. The severity of such an impact is partially dependent upon the intensity of soil reduction and the concentration of salt in floodwater.Réponse de Pinus taeda L à l'inondation et à la salinité. L'effet d'une inondation (F) seule ou accompagnée par la salinité (50 mol/m3) sur le semis de Pinus taeda L a été déterminé. L'effet de l'inondation a été évalué en mesurant le potentiel d'oxydation et de réduction (Eh) du sol. Le potentiel d'oxydation et de réduction dans les pots témoins était compris entre +400 et +450 mV alors qu'il était réduit de -50 à -140 mV dans les pots inondés (fig 1). La conductance stomatique (g) et l'assimilation nette du carbone (A) ont été réduites de façon significative dans les pots soumis à l'inondation (F) d'une part et l'inondation/salinité (FS) d'autre part. La conductance stomatique moyenne était de 120 mmol H2O m-2s-1 dans les témoins et de 51 et 45 mmol H2O m-2s -1 pour les pots seulements inondés ou accompagnés par la salinité, respectivement. L'assimilation du carbone était réduite de 5,82 mol CO2 m-2 s-1 dans les témoins à 2,22 et 0,9 mol CO2 m-2 s-1 pour les pots F et FS, respectivement. La relation A-CI indique que l'inondation seul ou accompagnée par la salinité affecte la capacité de la photosynthèse du P taeda L par un puissant effet non stomatique, mais aussi de façon significative par la régulation stomatique (fig 4). L'augmentation du poids sec par plant a été significativement réduite de 24,38 g dans les témoins à 10,9 et 8,22 g dans les F et FS, respectivement (tableau II). Ces réductions représentent 59% et 66% pour les F et FS. Ces résultats suggèrent que : - le P taeda L montre une sensibilité considérable à l'eau salée dans les intervalles testés; - la régénération et la survie de cette espèce sont sérieusement affectées dans les endroits où l'intrusion de l'eau salée est assez fréquente. La sévérité de cet impact dépend partiellement de la diminution du potentiel de réduction du sol et du degré de salinité de l'eau

Effects of crude oil on survival, morphology, and anatomy of two aquatic macrophytes from the Amazon floodplains

Aquatic herbaceous macrophytes grow in profusion in the Amazon fertile varzea floodplains. A large number of species occur but only a few are particularly abundant, supporting food chains, contributing substantially to carbon and nutrient cycles. Their growth and role in the ecosystem depend, among other, on its life cycles and habits, floating or semi-aquatic. Although in the last decades, petrolif-erous activity intensified in the Central Amazon region and so did oil spills, the effect of petroleum on the native aquatic plants is unknown. The present study was designed to test experimentally the survival and morpho-anatomical modifications of the free floating water hyacinth Eichhornia crassipes and the semi-aquatic grass Echinochloa polystachya to 10 different concentrations of crude oil. Higher concentrations of crude oil caused the mortality in both species; however, lethal dose (LD50) values showed that E. polystachya was more sensitive than E. crassipes. Despite the higher tolerance of E. crassipes, the inhibition of root and leaf growth as well as anatomical modifications in leaves were registered in higher concentrations. Additionally, the oil caused a reduction in leaf numbers in both species. Although mortality of the floating species was lower, it may increases over time, since important alterations in morphology and anatomy occurred. These results show that oil spills in the Amazon varzea can cause severe alterations in the aquatic flora and in the floodplain dynamics. © 2009 Springer Science+Business Media B.V