A Modeling System to Assess Land Cover Land Use Change Effects on SAV Habitat in the Mobile Bay Estuary

Estuarine ecosystems are largely influenced by watersheds directly connected to them. In the Mobile Bay, Alabama watersheds we examined the effect of land cover and land use (LCLU) changes on discharge rate, water properties, and submerged aquatic vegetation, including freshwater macrophytes and seagrasses, throughout the estuary. LCLU scenarios from 1948, 1992, 2001, and 2030 were used to influence watershed and hydrodynamic models and evaluate the impact of LCLU change on shallow aquatic ecosystems. Overall, our modeling results found that LCLU changes increased freshwater flows into Mobile Bay altering temperature, salinity, and total suspended sediments (TSS). Increased urban land uses coupled with decreased agricultural/pasture lands reduced TSS in the water column. However, increased urbanization or agricultural/pasture land coupled with decreased forest land resulted in higher TSS concentrations. Higher sediment loads were usually strongly correlated with higher TSS levels, except in areas where a large extent of wetlands retained sediment discharged during rainfall events. The modeling results indicated improved water clarity in the shallow aquatic regions of Mississippi Sound and degraded water clarity in the Wolf Bay estuary. This integrated modeling approach will provide new knowledge and tools for coastal resource managers to manage shallow aquatic habitats that provide critical ecosystem services.     

The effect of sulfide on alpha-glucosidases: implications for starch degradation in anaerobic bioreactors

Membrane associated alpha-glucosidase activity was investigated in a methanogenic bioreactor (MR) and a biosulfidogenic bioreactor (SR). Temperature and pH optima studies showed temperature optima of 50 degrees C and pH optima of 8.0 for the alpha-glucosidases from both the MR and SR. Sulfide (at a concentration of 150 mg l(-1)) resulted in the complete loss of all alpha-glucosidase activity in both the MR and SR. beta-Glucosidase activities in our bioreactors were previously shown to be stimulated in the presence of sulfide. alpha-Glucosidases, in contrast, are inhibited by sulfide. This differential effect of sulfide on alpha-glucosidase and beta-glucosidase activities is highlighted and is of crucial consequence to the respective degradation and utilization of starch and cellulose substrates in natural anaerobic environments and anaerobic bioreactors specifically designed for the accelerated digestion of wastewater sludge under biosulfidogenic conditions.     

Uptake and transformation of phenol and chlorophenols by hairy root cultures of Daucus carota, Ipomoea batatas and Solanum aviculare

Hairy root cultures of Daucus carota L., Ipomoea batatas L. and Solanum aviculare Forst were investigated for their susceptibility to the highly toxic pollutants phenol and chlorophenols and for the involvement of inherent peroxidases in the removal of phenols from liquid media. Roots of D. carota grew normally in medium containing 1000 micromol l(-1) of phenol, whilst normal growth of roots of I. batatas and S. aviculare was only possible at levels up to 500 micromol l(-1). In the presence of chlorophenols, normal root growth was possible only in concentrations not exceeding 50 micromol l(-1), except for I. batatas which was severely affected at all concentrations. Despite the reduction in biomass, the growth of S. aviculare cultures was sustained in medium containing up to 2000 micromol l(-1) of phenol or 2-chlorophenol, and up to 500 micromol l(-1) of 2,6-dichlorophenol. The amounts of phenol removed by the roots within 72 h of treatment were 72.7%, 90.7% and 98.6% of the initial concentration for D. carota, I. batatas and S. aviculare, respectively. For the removal of 2,6-dichlorophenol the values were, respectively, 83.0%, 57.7% and 73.1%. Phenols labelled with 14C were absorbed by the root tissues and condensed with highly polar cellular substances as well as being incorporated into the cell walls or membranes. The results suggest that S. aviculare, an ornamental plant, would be best suited for remediation trials under field conditions.     

Comparison of particle light scattering and fine particulate matter mass in central California

Particle light scattering (Bsp) from nephelometers and fine particulate matter (PM2.5) mass determined by filter samplers are compared for summer and winter at 35 locations in and around California's San Joaquin Valley from December 2, 1999 to February 3, 2001. The relationship is described using particle mass scattering efficiency (sigmasp) derived from linear regression of Bsp on PM2.5 that can be applied to estimated PM2.5 from nephelometer data within the 24-hr filter sampling periods and between the every-6th-day sampling frequency. An average of sigmaSp = 4.9 m2/g was found for all of the sites and seasons; however, sigmasp averaged by site type and season provided better PM2.5 estimates. On average, the sigmasp was lower in summer than winter, consistent with lower relative humidities, lower fractions of hygroscopic ammonium nitrate, and higher contributions from fugitive dust. Winter average sigmasp were similar at non-source-dominated sites, ranging from 4.8 m2/g to 5.9 m2/g. The sigmasp was 2.3 m2/g at the roadside, 3.7 m2/g at a dairy farm, and 4.1 m2/g in the Kern County oilfields. Comparison of Bsp from nephelometers with and without a PM2.5 inlet at the Fresno Supersite showed that coarse particles contributed minor amounts to light scattering. This was confirmed by poorer correlations between Bsp and coarse particulate matter measured during a fall sampling period.     

Feasibility of soil dust source apportionment by the pyrolysis-gas chromatography/mass spectrometry method

This study tested the feasibility of using pyrolysis (Py)-gas chromatography (GC)/mass spectrometry (MS) to obtain organic chemical species data suitable for source apportionment modeling of soil-derived coarse particulate matter (PM10) dust on ambient filters. A laboratory resuspension apparatus was used with known soils to generate simulated receptor filter samples loaded with approximately 0.4 mg of PM10 dust, which is within the range of mass loading on ambient filters. Py-GC/MS at 740 degrees C generated five times more resolvable compounds than were obtained with thermal desorption GC/MS at 315 degrees C. The identified compounds were consistent with literature from Py experiments using larger samples of bulk soils. A subset of 91 organic species out of the 178 identified Py products was used as input to CMB8 software in a demonstration of source apportionment using laboratory-generated mixtures simulating ambient filter samples. The 178 quantified organic species obtained by Py of soil samples is an improvement compared with the 38 organic species obtained by thermal desorption of soils and the four functionally defined organic fractions reported by thermal/ optical reflectance. Significant differences in the concentration of specific species were seen between samples from different sites, both geographically distant and close, using analysis of variance and cluster analysis. This feasibility study showed that Py-GC/MS can generate useful source profile data for receptor modeling and justifies continued method development.     

Quantifying biases in marine-protected-area placement relative to abatable threats

Marine protected areas (MPAs) are a critical defense against biodiversity loss in the world's oceans, but to realize near-term conservation benefits, they must be established where major threats to biodiversity occur and can be mitigated. We quantified the degree to which MPA establishment has targeted stoppable threats (i.e., threats that can be abated through effectively managed MPAs alone) by combining spatially explicit marine biodiversity threat data in 2008 and 2013 and information on the location and potential of MPAs to halt threats. We calculated an impact metric to determine whether countries are protecting proportionally more high- or low-threat ecoregions and compared observed values with random protected-area allocation. We found that protection covered <2% of ecoregions in national waters with high levels of abatable threat in 2013, which is ∼59% less protection in high-threat areas than if MPAs had been placed randomly. Relatively low-threat ecoregions had 6.3 times more strict protection (International Union for Conservation of Nature categories I–II) than high-threat ecoregions. Thirty-one ecoregions had high levels of stoppable threat but very low protection, which presents opportunities for MPAs to yield more significant near-term conservation benefits. The extent of the global MPA estate has increased, but the establishment of MPAs where they can reduce threats that are driving biodiversity loss is now urgently needed.     

Larval fish assemblages in Independencia Bay,Pisco, Peru: temporal and spatial relationships

The structure of the larval fish assemblages in Independencia Bay on the coast of Peru was examined using a combination of univariate and multivariate techniques. The plankton of Independencia Bay was sampled during 2000, to ascertain ichthyoplankton composition, abundance, and seasonality. These data were used to assess the function of the bay as spawning and nursery grounds and were related to the regional oceanography. In total, 16,156 fish larvae, representing 34 families, 48 genera, and 48 species were collected. Engraulidae, Normanichthyidae, Blenniidae, Gobiesocidae, Haemulidae, Labrisomidae, Pinguipedidae, and Atherinidae comprised 96.8% of the larvae captured; the remaining 3.2% included 26 families. Greatest mean larval fish densities, 319–1,381 per 100 m³, were recorded between September and November, suggesting a major spring spawning period. The most abundant fish larvae during this period were preflexion stage mote sculpins (Normanichthyidae) and newly hatched and preflexion stage anchovies (Engraulidae). A second, smaller summer peak was dominated by preflexion stage anchovies, followed by preflexion stage mote sculpins. The occurrence of high larval fish densities and the wide range of larval stages suggest that Independencia Bay is a regionally important spawning and nursery ground for marine fish. The principal component analysis showed that temperature and salinity were the dominant variables within the first two principal components, which accounted for 74.4% of the variation in environmental conditions. These conditions varied over time, station, and depth; however, interaction terms could not clearly be identified. Fitting a multinomial logistic model showed that larval fish assemblages and environmental conditions were associated in a complex way. The spring and summer ichthyoplankton abundance peaks in Independencia Bay coincided with high zooplankton standing stock and also coincided approximately with the periods of increased upwelling in the area.Communicated by O. Kinne, Oldendorf/Luhe