Cultivating Chlorella vulgaris and Scenedesmus quadricauda microalgae to degrade inorganic compounds and pesticides in water

Environmental Science and Pollution Research - This work evaluates the possibility of cultivating Scenedesmus quadricauda and Chlorella vulgaris microalgae in wastewater from the hydroponic...     

The Cost of Co-viability in the Australian Northern Prawn Fishery

Fisheries management must address multiple, often conflicting objectives in a highly uncertain context. In particular, while the bio-economic performance of trawl fisheries is subject to high levels of biological and economic uncertainty, the impact of trawling on broader biodiversity is also a major concern for their management. The purpose of this study is to propose an analytical framework to formally assess the trade-offs associated with balancing biological, economic and non-target species conservation objectives. We use the Australian Northern Prawn Fishery (NPF), which is one of the most valuable federally managed commercial fisheries in Australia, as a case study. We develop a stochastic co-viability assessment of the fishery under multiple management objectives. Results show that, due to the variability in the interactions between the fishery and the ecosystem, current management strategies are characterized by biological and economic risks. Results highlight the trade-offs between respecting biological, economic and non-target species conservation constraints at each point in time with a high probability and maximizing the net present value of the fishery.     

Benthic macrofaunal assemblages of the San Francisco Estuary and Delta, USA

The spatial and temporal distribution of macrobenthic assemblages in the San Francisco Estuary and Sacramento–San Joaquin River Delta were identified using hierarchical cluster analysis of 501 samples collected between 1994 and 2008. Five benthic assemblages were identified that were distributed primarily along the salinity gradient: (1) a polyhaline assemblage that inhabits the Central Bay, (2) a mesohaline assemblage that inhabits South Bay and San Pablo Bay, (3) a low-diversity oligohaline assemblage primarily in Suisun Bay, (4) a low-diversity sand assemblage that occurs at various locations throughout the Estuary, and (5) a tidal freshwater assemblage in the Delta. Most sites were classified within the same assemblage in different seasons and years, but a few sites switched assemblage designations in response to seasonal changes in salinity from freshwater inflows.     

Patterns and sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in surficial sediments of Lakes Erie and Ontario

This study determines spatial trends and congener patterns of 2378-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in surficial sediments of Lakes Erie and Ontario. Sediments are enriched in 2378-PCDFs in Lake Ontario, and the PCDD/F concentrations increased from shallow near-shore sediments towards deep-water depositional zone sediments. In Lake Erie, sediments were dominated by octachlorodibenzo-p-dioxin, and the highest PCDD/F concentrations were observed in the western basin and the southern shoreline of the central basin with a decrease towards the eastern basin and the northern shoreline of the central basin. Principal components analysis revealed that chemical manufacture and disposal of chemical waste along the Niagara River has been a major PCDD/F source to Lake Ontario; while PCDD/Fs in Lake Erie are from multiple sources including industrial sources along the Detroit River, major tributaries along the southern shoreline of the lake, and atmospherically-derived material from the upper lakes and connecting channels.     

Mercury cycling in surface water, pore water and sediments of Mugu Lagoon, CA, USA

Mugu Lagoon is an estuary in southern California, listed as impaired for mercury. In 2005, we examined mercury cycling at ten sites within at most four habitats. In surface water (unfiltered and filtered) and pore water, the concentration of total mercury was correlated with methylmercury levels (R2=0.29, 0.26, 0.27, respectively, p<0.05), in contrast to sediments, where organic matter and reduced iron levels were most correlated with methylmercury content (R2=0.37, 0.26, respectively, p<0.05). Interestingly, levels for percent methylmercury of total mercury in sediments were higher than typical values for estuarine sediments (average 5.4%, range 0.024-38%, n=59), while pore water methylmercury Kd values were also high (average 3.1, range 2.0-4.2l kg(-1), n=39), and the estimated methylmercury flux from sediments was low (average 1.7, range 0.14-5.3ng m(-2) day(-1), n=19). Mercury levels in predatory fish tissue at Mugu are >0.3ppm, suggesting biogeochemical controls on methylmercury mobility do not completely mitigate methylmercury uptake through the food web.     

Do evergreen and deciduous trees have different effects on net N mineralization in soil?

Evergreen and deciduous plants are widely expected to have different impacts on soil nitrogen (N) availability because of differences in leaf litter chemistry and ensuing effects on net N mineralization (N(min)). We evaluated this hypothesis by compiling published data on net N(min) rates beneath co-occurring stands of evergreen and deciduous trees. The compiled data included 35 sets of co-occurring stands in temperate and boreal forests. Evergreen and deciduous stands did not have consistently divergent effects on net N(min) rates; net N(min) beneath deciduous trees was higher when comparing natural stands (19 contrasts), but equivalent to evergreens in plantations (16 contrasts). We also compared net N(min) rates beneath pairs of co-occurring genera. Most pairs of genera did not differ consistently, i.e., tree species from one genus had higher net N(min) at some sites and lower net N(min) at other sites. Moreover, several common deciduous genera (Acer, Betula, Populus) and deciduous Quercus spp. did not typically have higher net N(min) rates than common evergreen genera (Pinus, Picea). There are several reasons why tree effects on net N(min) are poorly predicted by leaf habit and phylogeny. For example, the amount of N mineralized from decomposing leaves might be less than the amount of N mineralized from organic matter pools that are less affected by leaf litter traits, such as dead roots and soil organic matter. Also, effects of plant traits and plant groups on net N(min) probably depend on site-specific factors such as stand age and soil type.     

LANDCARE AND COMMUNITY-LED WATERSHED MANAGEMENT IN VICTORIA,AUSTRALIA1

ABSTRACT: Australia's ‘Landcare’ program is a community-based participatory program established by government to tackle the problem of land degradation. Landcare involves thousands of Australians working together in locally based groups, tackling problems of common concern. Government and community are now looking to ‘scale up’ the Landcare idea to a regional level. State and territory governments have moved to create regional (often watershed-based) frameworks for land management planning and resource conservation, in accordance with the concept of integrated watershed management. Growing out of the success of community involvement in Landcare, many of these approaches involve the community. However scaling up of the Landcare idea introduces problems of both time and space. There have been a number of problems experienced in the implementation of Landcare and integrated watershed management. These problems include the equitable delineation of membership on decision-making bodies; the raising of sufficient funds for program implementation; and the coordination of a diversity of governmental layers, planning processes and management programs. This paper reviews how the State of Victoria has responded to these challenges and suggests what challenges remain.     

Terrestrial liming benefits birds in an acidified forest in the northeast

Studies in Europe have reported negative effects of acid deposition on forest birds, and research in North America has identified links between forest bird abundance and rates of acid deposition. We examined the bird community in an acidified forest in central Pennsylvania (USA) and evaluated the effects of terrestrial lime application on birds. We used a before-after control-impact (BACI) study design, with one year of observation before (2003) and three years after lime application (2004, 2005, and 2006). Between the 2003 and 2004 field seasons, 4500 kg/ha of dolomitic lime were applied to two of four 100-ha watersheds. Each year, we monitored bird abundance and Ovenbird (Seiurus aurocapilla) eggshell thickness and territory size. Soil and snail abundance data were also collected. The bird community and territory size results indicated that the study area may be providing low-quality habitat for forest birds, perhaps as a result of acid deposition. We found lower forest bird abundances than have been found in less acidified areas of Pennsylvania, and larger Ovenbird territory sizes than have been found in other studies. We found a significant positive relationship between soil calcium and bird abundance, indicating that soil calcium may affect bird abundance. Liming increased soil calcium and pH and led to increased snail and bird abundances. After liming, bird abundance was positively related to snail abundance. No significant changes occurred in Ovenbird territory size or eggshell thickness. Our results suggest that acid deposition could be responsible for reduced bird abundance, and that liming is a potential mitigation technique.