Changes in biochemical and fatty acid composition of the razor clam <Emphasis Type="Italic">Solen marginatus</Emphasis> (Solenidae: Bivalvia) during larval development

Aquaculture studies have revealed that polyunsaturated fatty acids are critical for maintaining substantial growth, survival and reproductive rates, and high food conversion efficiencies for a wide variety of marine and freshwater organisms. The aim of this study was to investigate the gross biochemical and fatty acid composition of both neutral and polar lipid compartments of the razor clam Solen marginatus throughout embryonic and larval development. High levels of stored reserves in S. marginatus eggs allow a short larval development, lasting only 8 days. The energy required for embryogenesis was obtained from stored proteins. During larval development from D-shaped veliger until settlement, protein, lipid, and carbohydrate reserves were indistinctly stored for metamorphosis. Although total lipids increased, fatty acids in both neutral and polar lipids decreased during embryonic development. The depots allow a short larval development in which settlement is reached with lower amounts of stored neutral and polar lipids than the contents found in the oocytes. Non-methylene-interrupted dienoic fatty acid levels were similar to those of some polyunsaturated fatty acids, with increasing percentages at the onset of metamorphosis. This study indicates that S. marginatus exhibits a different pattern in the use of gross biochemical and fatty acid reserves during larval development compared to other razor clam and bivalve species, mainly due to the large size of its eggs and the short larval development stage reported in this species.     

Use of multiple tools to assess the feeding preference of coastal dolphins

The feeding preferences of the coastal dolphins Pontoporia blainvillei and Sotalia guianensis in south-eastern Brazil (21o18′S–22o25′S) were assessed through the prey’s index of relative importance (IRI), total mercury concentration (Hg_tot), and stable isotopic (δ¹⁵N and δ¹³C) to compare their efficiency in the discrimination of prey contribution to the predators’ diet. The IRI was the best tool to describe the dolphins’ preference, while Hg_tot and δ¹⁵N seemed to be efficient as a trophic marker when the diet is made up of prey of varying sizes, as observed in S. guianensis. Both dolphins presented lighter δ¹⁵N than their prey species, which is an unusual pattern. However, as the sample size to isotope ratios analysis was small, especially to the dolphins, the results should be considered with caution, and further studies are necessary to corroborate these findings. The δ¹³C values characterized a typical coastal food chain, confirming the preferential area of these species.     

Modeling an exploited rocky coastal ecosystem: Bahia Tortugas, Mexico

A trophic structure model of the rocky coastal ecosystem in Bahia Tortugas, Mexico was constructed using Ecopath software to represent the main biomass flows in the system. Data for the model came from field observations (biomass estimates, stomach contents, and ecological observations for sea snails, abalones, lobster, some demersal finfishes, and macroalgae) carried out through ten field trips from 2006 to 2008. The results provide a snapshot of how the ecosystem operates. The model considers 23 functional groups. The total system throughput was 553 t/km²/year, 57% corresponds to internal consumption, 28% to respiration, 14% becomes detritus, and only 1% is removed through commercial fishing. The model suggests that even for exploited populations, predation and competition are heavier stresses than current fishing effort; however, because spiny lobster showed the second highest keystoneness’ index value, increasing fishing pressure on this group could strongly impact the entire ecosystem. We believe that this model has the potential to support management by allowing the exploration of the potential impacts of different fishing decisions at ecosystem level.     

Arsenic and trace metals in river water and sediments from the southeast portion of the Iron Quadrangle, Brazil

The Iron Quadrangle has been one of the most important gold production regions in Brazil since the end of the seventeenth century. There, arsenic occurs in close association with sulfide-rich auriferous rocks. The most abundant sulfide minerals are pyrite and arsenopyrite, yet trace metal sulfides occur in subordinate phases as well. Historical mining activities have been responsible for the release of As and trace metals to both aquatic and terrestrial environments close to mining sites in the region. Therefore, this study was aimed to evaluate the distribution and mobility of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn in streams in the southeast portion of the Iron Quadrangle between the municipalities of Ouro Preto and Mariana, the oldest Brazilian Au mining province. Total concentrations of some trace metals and arsenic in water were determined. The four-stage sequential extraction procedure proposed by the commission of the European Communities Bureau of Reference (BCR) was used to investigate the distribution of these elements in stream sediments. Arsenic concentration in water was >10 ??g L^???1 (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) at all sampling sites, varying between 36.7 and 68.3 ??g L^???1. Sequential extraction in sediments showed high concentrations of As and trace metals associated with easily mobilized fractions.     

Bioluminescent yeast estrogen assay (BLYES) as a sensitive tool to monitor surface and drinking water for estrogenicity

Estrogenic Endocrine Disrupting Chemicals (EDCs) are a concern due to their ubiquity and recognized adverse effects to humans and wildlife. Methods to assess exposure to and associated risks of their presence in aquatic environment are still under development. The aim of this work is to assess estrogenicity of raw and treated waters with different degrees of pollution. Chemical analyses of selected EDCs were performed by liquid chromatography-tandem mass spectrometry, and estrogenic activity was evaluated using in vitro bioluminescent yeast estrogen assay (BLYES). Most raw water samples (18/20) presented at least one EDC and 16 rendered positive in BLYES. When EDCs were detected, the bioassay usually provided a positive response, except when only bisphenol A was detected at low concentrations. The highest values of estrogenic activity were detected in the most polluted sites. The maximum estrogenic activity observed was 8.7 ng equiv. of E2 L(-1). We compared potencies observed in the bioassay to the relative potency of target compounds and their concentrations failed to fully explain the biological response. This indicates that bioassay is more sensitive than the chemical approach either detecting estrogenic target compounds at lower concentrations, other non-target compounds or even synergistic effects, which should be considered on further investigations. We have not detected either estrogenic activity or estrogenic compounds in drinking water. BLYES showed good sensitivity with a detection limit of 0.1 ng equiv. E2 L(-1) and it seems to be a suitable tool for water monitoring.     

Quantifying the Effects of Forest Management Strategies on the Production of Forest Values: Timber,Carbon, Oxygen,Water, and Soil

Forest management practices alter forest structure quantified with ecosystem characteristics and values. In this paper, we utilized a forest management simulation model to assess the effects of three forest management strategies focusing on timber production, carbon sequestration, oxygen production, soil erosion, and water production of a forest management unit in Turkey. A forest simulation model “ETÇAPSimülasyon” was developed and used to project forest ecosystem development over 100 years under three forest management policies of timber-oriented forest management (TFM), multipurpose forest management (MFM), and no intervention (NI). The results showed that TFM strategy produced more timber and its net present value than MFM and NI strategies did. The amount of carbon sequestration and oxygen production potential was also found to be the highest with TFM strategy than with the MFM and NI strategies. Compared with the other strategies, however, NI strategy produced the highest amount of water production and soil losses over the planning horizon. The effects of a forest management strategy depend mainly on the initial forest structure, the rate of development and the level of forest management interventions. Therefore, forest dynamics under various management strategies should be explained before the final management decision. Understanding long-term effects of any management strategies on forest structure will provide the basis for better reaching the management objectives.     

Using data mining to predict soil quality after application of biosolids in agriculture

The amount of biosolids recycled in agriculture has steadily increased during the last decades. However, few models are available to predict the accompanying risks, mainly due to the presence of trace element and organic contaminants, and benefits for soil fertility of their application. This paper deals with using data mining to assess the benefits and risks of biosolids application in agriculture. The analyzed data come from a 10-yr field experiment in northeast France focusing on the effects of biosolid application and mineral fertilization on soil fertility and contamination. Biosolids were applied at agriculturally recommended rates. Biosolids had a significant effect on soil fertility, causing in particular a persistent increase in plant-available phosphorus (P) relative to plots receiving mineral fertilizer. However, soil fertility at seeding and crop management method had greater effects than biosolid application on soil fertility at harvest, especially soil nitrogen (N) content. Levels of trace elements and organic contaminants in soils remained below legal threshold values. Levels of extractable metals correlated more strongly than total metal levels with other factors. Levels of organic contaminants, particularly polycyclic aromatic hydrocarbons, were linked to total metal levels in biosolids and treated soil. This study confirmed that biosolid application at rates recommended for agriculture is a safe option for increasing soil fertility. However, the quality of the biosolids selected has to be taken into account. The results also indicate the power of data mining in examining links between parameters in complex data sets.     

Assessing the environmental performance of urban wastewater systems using the INSA model: application to the Algés-Alcântara wastewater system, in Portugal

Although the application of complex integrated models to wastewater systems is useful, it is often difficult to implement and not always suitable for the design of new systems or for their rehabilitation. Integrated simple approaches that allow assessing the environmental performance of urban wastewater systems may be advantageous, especially during the initial phases of the system planning process. This paper presents an original, straightforward approach that can be used for planning, design and operation of urban wastewater systems. The INtegrated Simplified Approach (INSA) combines the concepts of performance indicators with mass balances and can be applied to wastewater systems as a management support tool, particularly in situations where there is lack of data, economic limitations or time constraints. The INSA was applied to the Algés-Alcantara wastewater system to evaluate its environmental performance and to simulate the individual or combined impact of the rehabilitation measures proposed, thus defining their priority. The results clearly indicate that, despite the investment already made upgrading the wastewater treatment plant (WWTP), the proposed interventions must be implemented to ensure an acceptable environmental performance of the system. In addition, the results demonstrate the significant pollution loads present in stormwater, frequently higher than the pollution loads discharged into receiving waters during dry weather.