The Sensitivity of Northern Groundwater Recharge to Climate Change: A Case Study in Northwest Alaska1

Clilverd, Hannah M., Daniel M. White, Amy C. Tidwell, and Michael A. Rawlins, 2011. The Sensitivity of Northern Groundwater Recharge to Climate Change: A Case Study in Northwest Alaska. Journal of the American Water Resources Association (JAWRA) 47(6):1228–1240. DOI: 10.1111/j.1752‐1688.2011.00569.x Abstract: The potential impacts of climate change on northern groundwater supplies were examined at a fractured‐marble mountain aquifer near Nome, Alaska. Well water surface elevations (WSE) were monitored from 2004‐2009 and analyzed with local meteorological data. Future aquifer response was simulated with the Pan‐Arctic Water Balance Model (PWBM) using forcings (air temperature and precipitation) derived from fifth‐generation European Centre Hamburg Model (ECHAM5) global circulation model climate scenarios for extreme and modest increases in greenhouse gases. We observed changes in WSE due to the onset of spring snowmelt, low intensity and high intensity rainfall events, and aquifer head recession during the winter freeze period. Observed WSE and snow depth compared well with PWBM‐simulated groundwater recharge and snow storage. Using ECHAM5‐simulated increases in mean annual temperature of 4‐8°C by 2099, the PWBM predicted that by 2099 later freeze‐up and earlier snowmelt will decrease seasonal snow cover by one to two months. Annual evapotranspiration and precipitation are predicted to increase 27‐40% (55‐81 mm) and 33‐42% (81‐102 mm), respectively, with the proportion of snowfall in annual precipitation decreasing on average 9‐25% (p < 0.05). The amount of snowmelt is not predicted to change significantly by 2099; however, a decreasing trend is evident from 2060 in the extreme ECHAM5 greenhouse gas scenario. Increases in effective precipitation were predicted to be great enough to sustain sufficient groundwater recharge.     

Mitochondrial DNA sequence variation in spiny lobsters: population expansion,panmixia, and divergence

To investigate population differentiation in a comparative and historical context, segments of the mitochondrial cytochrome c oxidase subunit I gene and the control region were sequenced in Panulirus argus from nine sites along approximately 1,500 km of the Northern Caribbean Sea (n = 326) and analyzed with respect to available panulirid data. A mismatch analysis and Fu’s F _S test uncovered a signature of historical population expansion around the time of the Last Glacial Maximum. Significant population structure was not detected in the area. The data supported a hypothesis of panmixia resulting from ongoing larval transport by ocean currents and historical population expansion. Despite high intraspecific divergence levels at COI within Panulirus argus and several other Panulirus species, genetic species identification through DNA barcoding was feasible using either a modified distance threshold or a character-based approach.     

Dissecting the drivers of population cycles: Interactions between parasites and mountain hare demography

There is a growing awareness that cyclic population dynamics in vertebrate species are driven by a complex set of interactions rather than a single causal factor. While theory suggests that direct host-parasite interactions may destabilise population dynamics, the interaction between host and parasite may also influence population dynamics through indirect effects that result in delayed responses to either density or to life-history traits. Using empirical data on mountain hares (Lepus timidus) infected with a nematode parasite (Trichostrongylus retortaeformis), we developed an individual-based model (IBM) that incorporated direct effects and delayed life-history effects (DLHEs) of a macroparasite, alternative transmission mechanisms and seasonality in host population dynamics. The full model describes mean characteristics of observed mountain hare time series and parasite abundance, but by systematically removing model structure we dissect out dynamic influences of DLHEs. The DLHEs were weakly destabilising, increasing the propensity for cyclic dynamics and suggesting DLHEs could be important processes in host-parasite systems. Further, by modifying model structure we identify a strong influence of parasite transmission mechanism on host population stability, and discuss the implications for parasite aggregation mechanisms, host movement and natural geographical variation in host population dynamics. The effect of T. retortaeformis on mountain hares likely forms part of a complex set of interactions that lead to population cycles.     

Integrated survey of water pollution in the Suquía River basin (Córdoba, Argentina)

We report a combined two-year seasonal monitoring of Suquía River basin using both chemical parameters and biomarkers measured in Jenynsia multidentata, aiming to correlate external levels of contaminants with the response of oxidative stress biomarkers in this fish. Identified pollution sources correspond to city sewage as well as agricultural and small industry activities downstream from Córdoba city. Physicochemical parameters integrated into a water quality index (WQI) were measured in Suquía River during dry and wet seasons. Ag, Mn, Cu, Cr, Ni, Fe, Pb and Zn were also monitored in water and sediment samples. Biomarkers include detoxication and antioxidant enzymes: catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST) and glutathione reductase (GR). Enzymes showed a pollution dependent response, with increased activities in fish collected close to the sewage exit and progressive drop further downstream, matching changes in the Water Quality index. The combined use of biomarkers with water quality parameters allowed both the identification of pollution sources and the evaluation of effects of contaminants on the aquatic biota.     

Plants as bio-monitors for Cs-137, Pu-238, Pu-239,240 and K-40 at the Savannah River Site

The Savannah River Site was constructed in South Carolina to produce plutonium (Pu) in the 1950s. Discharges associated with these now-ceased operations have contaminated large areas within the site, particularly streams associated with reactor cooling basins. Evaluating the exposure risk of contamination to an ecosystem requires methodologies that can assess the bioavailability of contaminants. Plants, as primary producers, represent an important mode of transfer of contaminants from soils and sediments into the food chain. The objective of this study was to identify local area plants for their ability to act as bio-monitors of radionuclides. The concentrations of cesium-137 ((137)Cs), potassium-40 ((40)K), (238)Pu and (239,240)Pu in plants and their associated soils were determined using γ and α spectrometry. The ratio of contamination concentration found in the plant relative to the soil was calculated to assess a concentration ratio (CR). The highest CR for (137)Cs was found in Pinus palustris needles (CR of 2.18). The correlation of soil and plant (137)Cs concentration was strong (0.76) and the R(2) (0.58) from the regression was significant (p = 0.006). This suggests the ability to predict the degree of (137)Cs contamination of a soil through analysis of the pine needles. The (238)Pu and (239,240)Pu concentrations were most elevated within the plant roots. Extremely high CR values were found in Sparganium americanum (bur-reed) roots with a value of 5.86 for (238)Pu and 5.66 for (239,240)Pu. The concentration of (40)K was measured as a known congener of (137)C. Comparing (40)K and (137)C concentrations in each plant revealed an inverse relationship for these radioisotopes. Correlating (40)K and (137)Cs was most effective in identifying plants that have a high affinity for (137)Cs uptake. The P. palustris and S. americanum proved to be particularly strong accumulators of all K congeners from the soil. Some species that were measured, warrant further investigation, are the carnivorous plant Utricularia inflata (bladderwort) and the emergent macrophyte Juncus effusus. For U. inflata, the levels of (137)Cs, (238)Pu, and (239,240)Pu (which were 3922, 8399, and 803 Bq kg(-1), respectively) in the leaves were extremely high. The highest (137)Cs concentration from the study was measured in the J. effusus root (5721 Bq kg(-1)).     

A coffee agroecosystem model: I. Growth and development of the coffee plant

This paper is the first of three on the coffee production system consisting of (1) the coffee plant, (2) coffee berry borer (CBB) and (3) the role of CBB parasitoids. A previous simulation model of the coffee plant was developed using data from Brazil where coffee phenology is characterized by distinct seasonal flowering (Gutierrez et al., 1998). In contrast, flowering in Colombia is continuous with low seasonality. To capture the differences in coffee phenology and growth in the two climatic regions, the Gutierrez et al. (1998) model was modified using new data from Colombia.The modifications to the model include:

(1)

The effect of solar radiation on floral buds initiation;

(2)

An age structure population model to track the daily input and development of the floral buds;

(3)

The effect of leaf water potential on breaking dormancy in flower buds, and hence on the timing and intensity of flowering;

(4)

The incorporation of both the vegetative and the reproductive demands to predict the photosynthetic rate.

(5)

The effect of low temperature on photosynthesis and defoliation.

Other aspects of the model were re-interpreted and refinements made to generalize its structure for use across coffee varieties and geographic areas. The model, without modification, realistically simulates field data from Brazil and two Colombian locations having different varieties, patterns of rainfall and hence flowering phenology.The model will be used as the base trophic level for incorporating CBB and high tropic levels effects, and for the analysis of management options in the coffee production system.     

Temporal variability of forest fires in eastern Amazonia

Widespread occurrence of fires in Amazonian forests is known to be associated with extreme droughts, but historical data on the location and extent of forest fires are fundamental to determining the degree to which climate conditions and droughts have affected fire occurrence in the region. We used remote sensing to derive a 23-year time series of annual landscape-level burn scars in a fragmented forest of the eastern Amazon. Our burn scar data set is based on a new routine developed for the Carnegie Landsat Analysis System (CLAS), called CLAS-BURN, to calculate a physically based burn scar index (BSI) with an overall accuracy of 93% (Kappa coefficient 0.84). This index uses sub-pixel cover fractions of photosynthetic vegetation, non-photosynthetic vegetation, and shade/burn scar spectral end members. From 23 consecutive Landsat images processed with the CLAS-BURN algorithm, we quantified fire frequencies, the variation in fire return intervals, and rates of conversion of burned forest to other land uses in a 32 400 km2 area. From 1983 to 2007, 15% of the forest burned; 38% of these burned forests were subsequently deforested, representing 19% of the area cleared during the period of observation. While 72% of the fire-affected forest burned only once during the 23-year study period, 20% burned twice, 6% burned three times, and 2% burned four or more times, with the maximum of seven times. These frequencies suggest that the current fire return interval is 5-11 times more frequent than the estimated natural fire regime. Our results also quantify the substantial influence of climate and extreme droughts caused by a strong El Ni?o Southern Oscillation (ENSO) on the extent and likelihood of returning forest fires mainly in fragmented landscapes. These results are an important indication of the role of future warmer climate and deforestation in enhancing emissions from more frequently burned forests in the Amazon.     

Cadmium, copper, lead, and zinc in Mugil cephalus from seven coastal lagoons of NW Mexico

The increasing order of the mean concentrations of Cd, Cu, and Zn in the tissues of Mugil cephalus of seven coastal lagoons of Sinaloa State (NW Mexico) was liver > gills > muscle, while for Pb it was gills > muscle ≥ liver. There were no differences between the mean concentrations of Cd and Pb of the three tissues determined in the samples of the seven lagoons and, although there were some significant differences, there was no indication of a latitude-related trend in the distribution of Cu and Zn: the Cu content of the muscle tended to be higher in the northern than in the southern lagoons, although in the case of the gills the highest and lowest mean values indicated an opposite trend, with the highest and lowest values in one southern and one northern lagoon. In the case of the liver, there were no differences and no indication of a regional trend. There were no differences in the mean Zn contents of muscle and gills; in the case of the liver, one of the lagoons of the central part of the state had a significantly higher value than one of the southern lagoons and all the rest had similar values. In addition, there was no clear indication of season-related differences in any of the three tissues. According to our results, the metal contents of the muscle of this species are not of concern for human health, since the allowable ingestion would be in the order of 0.9 kg/day.     

Repetitive extragenic palindromic PCR (REP-PCR) as a method used for bulking process detection in activated sludge

Bulking of activated sludge is a world-widely prevalent problem and can lead to loss of bio-oxidation, further deterioration of effluent quality, and even to a complete breakdown of the entire treatment process. Most common reasons of bulking are bacterial community changes, especially excessive growth of filamentous bacteria or excess of biopolymers on surface of non-filamentous microbes. Because of complex nature of the bulking phenomenon, the successful bulking control strategy finding is still a very important need awaiting new options and advices. The repetitive extragenic palindromic PCR (REP-PCR) fingerprinting method has been applied to distinguish bacterial community in non-bulking and bulking activated sludge. The characteristic REP-PCR fingerprinting patterns, using the Ward??s clustering method, have been analyzed to determine homology/similarity relation between particular non-bulking and bulking sludge sampling. The received clustering results were in high concordance with activated sludge typing done based on physicochemical sludge analysis. The choice and application of molecular typing method in sludge analysis will depend upon the needs, skill level, and resources of the laboratory. The proposed REP-PCR method and statistical analysis of fingerprinting patterns seems to be simple, rapid, and effective methods to show differences between population in non-bulking and bulking activated sludge. It is easy to implement, and it may be useful for routinely activated sludge monitoring as well as may be helpful in early detection of bulking process.