Multi-scale marine biodiversity patterns inferred efficiently from habitat image processing

Cost-effective proxies of biodiversity and species abundance, applicable across a range of spatial scales, are needed for setting conservation priorities and planning action. We outline a rapid, efficient, and low-cost measure of spectral signal from digital habitat images that, being an effective proxy for habitat complexity, correlates with species diversity and requires little image processing or interpretation. We validated this method for coral reefs of the Great Barrier Reef (GBR), Australia, across a range of spatial scales (1 m to 10 km), using digital photographs of benthic communities at the transect scale and high-resolution Landsat satellite images at the reef scale. We calculated an index of image-derived spatial heterogeneity, the mean information gain (MIG), for each scale and related it to univariate (species richness and total abundance summed across species) and multivariate (species abundance matrix) measures of fish community structure, using two techniques that account for the hierarchical structure of the data: hierarchical (mixed-effect) linear models and distance-based partial redundancy analysis. Over the length and breadth of the GBR, MIG alone explained up to 29% of deviance in fish species richness, 33% in total fish abundance, and 25% in fish community structure at multiple scales, thus demonstrating the possibility of easily and rapidly exploiting spatial information contained in digital images to complement existing methods for inferring diversity and abundance patterns among fish communities. Thus, the spectral signal of unprocessed remotely sensed images provides an efficient and low-cost way to optimize the design of surveys used in conservation planning. In data-sparse situations, this simple approach also offers a viable method for rapid assessment of potential local biodiversity, particularly where there is little local capacity in terms of skills or resources for mounting in-depth biodiversity surveys.     

Protective effects of Peganum harmala extracts on thiourea-induced diseases in adult male rat

Cancers and hepatoprotective prevention using traditional medicines have attracted increasing interest. The aim of our study was to characterize the putative protective effects of ethanol and chloroform extracts of Peganum harmala on thiourea-induced diseases in adult male rat. We seek to determine the effects of these plant extracts on body weight, thyroid and endocrine cancer parameters. In addition the putative hepatoprotective effect was checked by the determination of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities and the bilirubin level in the blood. Our data show that ethanol and chloroform extracts of Peganum harmala protected the animal against the carcinogenic effects induced by thiourea since neuron-specific enolase (NSE) and thyroglobulin (TG) levels were back to the normal range. In addition, the observed-hepatocytotoxicity after thiourea treatment was greatly reduced (AST and ALT activities were respectively 270 IU/l and 60 IU/l and in the same order of magnitude as in the untreated rats) as well as the bilirubin levels (6 micromol/l) especially for animals receiving the choroform preparation. Therefore we may suggest that extracts of Peganum harmala are efficient to reduce the toxicity induced by thiourea in male rat as far as the above parameters are concerned.     

Removal of carbamazepine from urban wastewater by sulfate radical oxidation

The occurrence of bioactive trace pollutants such as pharmaceuticals in natural waters is an emerging issue. Numerous pharmaceuticals are not completely removed in conventional wastewater treatment plants. Advanced oxidation processes may represent an interesting alternative to completely mineralize organic trace pollutants. In this article, we show that sulfate radicals generated from peroxymonosulfate/Co^II are more efficient than hydroxyl radicals generated from the Fenton’s reagent (H₂O₂/Fe^II) for the degradation of the pharmaceutical compound, carbamazepine. The second-order rate constant for the reaction of SO₄ ^·− with carbamazepine is 1.92·10⁹ M⁻¹ s⁻¹. In laboratory grade water and in real urban wastewater, SO₄ ^·− yielded a faster degradation of carbamazepine compared to HO^· . Under strongly oxidizing conditions, a nearly complete mineralization of carbamazepine was achieved, while under mildly oxidizing conditions, several intermediates were identified by LC–MS. These results show for the first time in real urban wastewater that sulfate radicals are more selective than hydroxyl radicals for the oxidation of an organic pollutant and may represent an interesting alternative in advanced oxidation processes.     

Phytoplankton food quality determines time windows for successful zooplankton reproductive pulses

Recruitment success at the early life stages is a critical process for zooplankton demography. Copepods often dominate the zooplankton in marine coastal zones and are prey of the majority of fish larvae. Hypotheses interpreting variations of copepod recruitment are based on the concepts of "naupliar predation," "nutritional deficiency," and "toxic effect" of diatom diets. Contradictory laboratory and field studies have reached opposite conclusions on the effects of diatoms on copepod reproductive success, blurring our view of marine food-web energy flow from diatoms to higher consumers by means of copepods. Here we report estimates of copepod feeding selectivity and reproduction in response to seasonally changing phytoplankton characteristics measured in a highly productive coastal upwelling area off the coast of central Chile. The variable phytoplankton diversity and changing food quality had a strong and highly significant impact on the feeding selectivity, reproduction, and larval survival of three indigenous copepod species. Seasonal changes in copepod feeding behavior were related to the alternating protozoan-diatom diets, mostly based on dinoflagellates and ciliates during winter and autumn (low highly unsaturated fatty acids [HUFA]/polyunsaturated fatty acids [PUFA] availability), but switched to a diet of centric and chain-forming diatoms (high HUFA/PUFA availability) during the spring/summer upwelling period. Ingestion of diatom cells induced a positive effect on egg production. However, a negative relationship was found between egg hatching success, naupliar survival, and diatom ingestion. Depending on the phytoplankton species, diets had different effects on copepod reproduction and recruitment. In consequence, it seems that the classical marine food web model does not apply to some coastal upwelling systems.