Photosynthetic performance of giant clams, Tridacna maxima and T. squamosa, Red Sea

Two species of giant clams, Tridacna maxima and T. squamosa, coexist in the Red Sea, but exhibit distinctly different depth distributions: T. maxima mostly occurs in shallow waters (reef flat and edge), while T. squamosa may occur down to the lower fore-reef slope. Giant clams have been described as mixotrophic, capable of both filter-feeding and photosynthesis due to algal symbionts (zooxanthellae), therefore, observed depth preferences were investigated in relation to possible differences in autotrophy vs. heterotrophy. This study was conducted from April to June 2004, at the reef near the Marine Science Station, Aqaba, Gulf of Aqaba, Red Sea, and in May 2007, at a reef near Dahab, Sinai Peninsula, Egypt. In situ measurements using a submersible pulse amplitude modulated fluorometer (Diving PAM), revealed no significant differences in effective PSII quantum yield (ΔF/Fm′) and relative electron transport rates (ETR) between the two species; but rapid light curves (ETR vs. light, photosynthetically active irradiance, PAR) showed significant differences in maximum photosynthetic rates (ETR_max), with 20% higher values in T. maxima. Chamber incubations displayed higher net and gross oxygen production by T. maxima (88.0 and 120.3 μmol O₂ cm⁻² mantle area day⁻¹) than T. squamosa (56.7 and 84.8 μmol O₂ cm⁻² mantle area day⁻¹); even under shading conditions (simulated depth of 20 m) T. maxima still achieved 93% of the surface gross O₂ production, whereas T. squamosa reached only 44%. A correlation was found between ETR and net photosynthesis measured as oxygen production (T. maxima: R ² = 0.53; T. squamosa: R ² = 0.61). Calculated compensation depth (CD) (gross photosynthesis equals respiration) in T. maxima (16 m) matches the maximum depth of occurrence in this study (17 m). By contrast, the CD of T. squamosa (9 m) was much shallower than the maximum vertical range (42 m). Findings suggest T. maxima is a strict functional photoautotroph limited by light, whereas T. squamosa is a mixotroph whose photoautotrophic range is extended by heterotrophy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Relationship between heavy metal concentrations of herbaceous plants and soils at four Pb-Zn mining sites in Yunnan, China

This paper studied the relationship between heavy metal concentrations of herbaceous plants and soils at four Pb-Zn mining sites in Yunnan, China. 50 herbaceous plant samples of 9 plant species from 4 families and 50 soil samples were collected and then ana1yzed for the tota1 concentrations of Pb, Cd, and Zn. The results showed that the average concentrations of Pb, Cd, and Zn in soil samples were 3772.83, 168.81, and 5385.65 mg/kg, respectively. The average concentrations of Pb, Cd, and Zn were 395.68, 28.14, and 1664.20 mg/kg in the shoots, and 924.12, 57.25, and 1778.75 mg/kg in the roots, respectively. Heterospecific plants at the same site and conspecific plants at various sites had different average levels of Pb, Cd, and Zn, both in the shoots and the roots. Enrichment coefficients of Pb, Cd, and Zn were greater than 1 in 2, 3, and 9 herbaceous plant samples, respectively. Translocation factors of Pb, Cd, and Zn were greater than 1 in 10, 17, and 25 herbaceous plant samples, respectively. In all 50 samples, the concentrations of Pb, Cd, and Zn between the shoots and the roots, the shoots, and the soils, and the roots and the soils had significant positive relationships.     

安捷伦液相/离子阱(XCT)质谱检测虾仁及家禽中的硝基呋喃代谢物

在液相/离子阱质谱上,利用液相/质谱/质谱方法对鸡肉及虾仁中硝基呋喃代谢物残留进行了定性定量分析.对于四种硝基呋喃代谢物,其定量限在0125到05μg·kg-1的范围内,分析结果完全满足欧盟的1μg·kg-1的最低检测限量的要求.     

Archetypical patterns and trajectories of land systems in Europe

Regional Environmental Change - Assessments of land-system change have dominantly focused on conversions among broad land-use categories, whereas intensity changes within these categories have...     

An empirical perspective for understanding climate change impacts in Switzerland

Regional Environmental Change - Planning for the future requires a detailed understanding of how climate change affects a wide range of systems at spatial scales that are relevant to humans....     

Temporal trends of lipophilic persistent organic pollutants in serum from Danish nulliparous pregnant women 2011–2013

The use of the lipophilic persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs) and several organochlorine pesticides (OCPs) has been prohibited for more than 30 years. In this study, we present the temporal trends of the lipophilic POP serum concentrations in Danish nulliparous pregnant women between 2011 and 2013. We randomly selected 197 pregnant women (gestational age 11–13) from the Aarhus Birth Cohort. The concentrations of the lipophilic POPs in the serum samples were analyzed using gas chromatography. The concentrations were corrected for total serum lipids. The statistical analysis was performed by regression analysis with adjustment for age, BMI, gestational age at blood draw, and smoking status. The serum concentrations of PCB 118, 138, 153, 156, 170, 180, 187, and hexachlorobenzen, trans-nonachlor, β-hexachlorocyclohexane (β-HCH), and p,p’-dichlorodiphenyldichloroethylene were lower in 2013 than in 2011. However, the oxychlordane concentration was lowest in 2011. The serum levels of most lipophilic POPs followed downward trends during the study period, which was expected, as these compounds has been banned for many years. The upward trend of oxychlordane was unexpected and presumably a chance finding.     

Differentiating the effects of climate and land use change on European biodiversity: A scenario analysis

Current observed as well as projected changes in biodiversity are the result of multiple interacting factors, with land use and climate change often marked as most important drivers. We aimed to disentangle the separate impacts of these two for sets of vascular plant, bird, butterfly and dragonfly species listed as characteristic for European dry grasslands and wetlands, two habitats of high and threatened biodiversity. We combined articulations of the four frequently used SRES climate scenarios and associated land use change projections for 2030, and assessed their impact on population trends in species (i.e. whether they would probably be declining, stable or increasing). We used the BIOSCORE database tool, which allows assessment of the effects of a range of environmental pressures including climate change as well as land use change. We updated the species lists included in this tool for our two habitat types. We projected species change for two spatial scales: the EU27 covering most of Europe, and the more restricted biogeographic region of ‘Continental Europe’. Other environmental pressures modelled for the four scenarios than land use and climate change generally did not explain a significant part of the variance in species richness change. Changes in characteristic bird and dragonfly species were least pronounced. Land use change was the most important driver for vascular plants in both habitats and spatial scales, leading to a decline in 50–100% of the species included, whereas climate change was more important for wetland dragonflies and birds (40–50 %). Patterns of species decline were similar in continental Europe and the EU27 for wetlands but differed for dry grasslands, where a substantially lower proportion of butterflies and birds declined in continental Europe, and 50 % of bird species increased, probably linked to a projected increase in semi-natural vegetation. In line with the literature using climate envelope models, we found little divergence among the four scenarios. Our findings suggest targeted policies depending on habitat and species group. These are, for dry grasslands, to reduce land use change or its effects and to enhance connectivity, and for wetlands to mitigate climate change effects.     

A review of ecosystem service benefits from wild bees across social contexts

In order to understand the role of wild bees in both social and ecological systems, we conducted a quantitative and qualitative review of publications dealing with wild bees and the benefits they provide in social contexts. We classified publications according to several attributes such as services and benefits derived from wild bees, types of bee–human interactions, recipients of direct benefits, social contexts where wild bees are found, and sources of changes to the bee–human system. We found that most of the services and benefits from wild bees are related to food, medicine, and pollination. We also found that wild bees directly provide benefits to communities to a greater extent than individuals. In the social contexts where they are found, wild bees occupy a central role. Several drivers of change affect bee–human systems, ranging from environmental to political drivers. These are the areas where we recommend making interventions for conserving the bee-human system.     

Development of a new method for the determination of residues of the neonicotinoid insecticide imidacloprid in juvenile chinook (Oncorhynchus tshawytscha) using ELISA detection

The neonicotinoid insecticide imidacloprid (IMI) has been proposed as an alternative to carbaryl for controlling indigenous burrowing shrimp on commercial oyster beds in Willapa Bay and Grays Harbor, Washington. A focus of concern over the use of this insecticide in an aquatic environment is the potential for adverse effects from exposure to non-target species residing in the Bay, such as juvenile Chinook (Oncorhynchus tshawytscha) and cutthroat trout (O. clarki). Federal registration and State permiting approval for the use of IMI will require confirmation that the compound does not adversely impact these salmonids following field applications. This will necessitate an environmental monitoring program for evaluating exposure in salmonids following the treatment of beds. Quantification of IMI residues in tissue can be used for determining salmonid exposure to the insecticide. Refinement of an existing protocol using liquid-chromatography mass spectrometry (LC-MS) detection would provide the low limits of quantification, given the relatively small tissue sample sizes, necessary for determining exposure in individual fish. Such an approach would not be viable for the environmental monitoring effort in Willapa Bay and Grays Harbor due to the high costs associated with running multiple analyses, however. A new sample preparation protocol was developed for use with a commercially available enzyme-linked immunosorbent assay (ELISA) for the quantification of IMI, thereby providing a low-cost alternative to LC-MS for environmental monitoring in Willapa Bay and Grays Harbor. Extraction of the analyte from the salmonid brain tissue was achieved by Dounce homogenization in 4.0 mL of 20.0 mM Triton X-100, followed by a 6 h incubation at 50-55 °C. Centrifugal ultrafiltration and reversed phase solid phase extraction were used for sample cleanup. The limit of quantification for an average 77.0 mg whole brain sample was calculated at 18.2 μg kg(-1) (ppb) with an average recovery of 79%. This relatively low limit of quantification allows for the analysis of individual fish. Using controlled laboratory studies, a curvelinear relationship was found between the measured IMI residue concentrations in brain tissue and exposure concentrations in seawater. Additonally, a range of IMI brain residue concentrations was associated with an overt effect; illustrating the utility of the IMI tissue residue quantification approach for linking exposure with defined effects.     

Prediction of Pollen-Mediated Gene Flow Between Fields of Red Clover (<Emphasis Type="Italic">Trifolium pratense</Emphasis>)

Pollen-mediated gene flow between red clover fields by bumblebees is predicted by estimating or simulating the parameters in a gene flow model for insect-pollinated crops. Generally, the predicted level of gene flow was found to depend on the visiting bee species and the spatial arrangement of the red clover fields. When the fields are close to each other, the gene flow depends mainly on the typical foraging distance of the visiting bee species, but when the fields are far apart, the gene flow between red clover fields is more sensitive to the distances between red clover fields than to the actual bumblebee species that pollinates the fields. Using the suggested methodology, the gene flow may be predicted in different agricultural scenarios. For example, if the gene flow between red clover fields is mediated by Bombus terrestris and the red clover fields that were assumed to be quadrates with sides of 100 m are separated by 200 m, then the median gene flow is predicted to be 0.17%.