Influence of seasonal variability in benthic invertebrate community structure on the use of biotic indices to assess the ecological status of a Portuguese estuary

The present study focused on the use of benthic invertebrate communities to assess the ecological quality of a Portuguese estuary characterized by strong seasonal changes and with eutrophication problems. Seasonal benthic samples were collected during a flood year and the methodology proposed by the WFD Portuguese group was used to classify benthic assemblages into five different quality classes. Factor analysis was applied to classify stations based on their physical-chemical status. Different classifications were obtained with different indices and among seasons and there was low agreement between indices and index-season interactions. Diversity indices were better correlated to eutrophication related variables than AMBI and ABC method. Predictable responses of benthic indices to anthropogenic stress symptoms were stronger during the dry period.     

Phytoplankton community structure defined by key environmental variables in Tagus estuary, Portugal

In this work, we analyze environmental (physical and chemical) and biological (phytoplankton) data obtained along Tagus estuary during three surveys, carried out in productive period (May/June/July) at ebb tide. The main objective of this study was to identify the key environmental factors affecting phytoplankton structure in the estuary. BIOENV analysis revealed that, in study period, temperature, salinity, silicate and total phosphorus were the variables that best explained the phytoplankton spatial pattern in the estuary (Spearman correlation, rho=0.803). A generalized linear model (GLM) also identified salinity, silicate and phosphate as having a high explanatory power (63%) of phytoplankton abundance. These selected nutrients appear to be consistent with the requirements of the dominant phytoplankton group, Baccilariophyceae. Apparently, phytoplankton community is adapted to fluctuations in light intensity, as suspended particulate matter did not come out as a key factor in shaping phytoplankton structure along Tagus estuary.     

A benthic survey of Aliwal Shoal and assessment of the effects of a wood pulp effluent on the reef

Aliwal Shoal lies south of Durban in South Africa and has been the subject of recent bathymetric, seafloor and benthic surveys. ANOVA of the biological data revealed that the biota were uniformly distributed on the reef with the exception of encrusting sponges and algae on rock. The variations in distribution of these biota were significant and, in the case of the encrusting sponges, appeared to be related to the discharge of a wood pulp effluent. Further evidence of this was suggested by stable isotope analyses of representative organisms. The encrusting sponges were recommended as good candidates for further monitoring of the effects of the wood pulp effluent on Aliwal Shoal as the effluent pipeline has been extended.     

On effects of trawling, benthos and sampling design

The evidence for the wider effects of fishing on the marine ecosystem demands that we incorporate these considerations into our management of human activities. The consequences of the direct physical disturbance of the seabed caused by towed bottom-fishing gear have been studied extensively with over 100 manipulations reported in the peer-reviewed literature. The outcome of these studies varies according to the gear used and the habitat in which it was deployed. This variability in the response of different benthic systems concurs with established theoretical models of the response of community metrics to disturbance. Despite this powerful evidence, a recent FAO report wrongly concludes that the variability in the reported responses to fishing disturbance mean that no firm conclusion as to the effects of fishing disturbance can be made. This thesis is further supported (incorrectly) by the supposition that current benthic sampling methodologies are inadequate to demonstrate the effects of fishing disturbance on benthic systems. The present article addresses these two erroneous conclusions which may confuse non-experts and in particular policy-makers.     

"嫦娥一号"探月卫星发射期间太阳活动现象监测

为发射"嫦娥一号"探月卫星,保障其在空间环境运行的安全和国家载人航天计划的正常实施,云南天文台全日面Hα色球望远镜为中国科学院空间环境研究预报中心实时提供太阳活动数据资料,协作完成特殊时期空间环境监测任务.     

Small plastic debris changes water movement and heat transfer through beach sediments

We investigated the physical properties of beaches contaminated with plastic fragments. We compared sediment cores from Hawai‘i Island’s Kamilo Beach, notable for plastic accumulation, to cores from a nearby beach. Compared to the nearby beach, Kamilo sediments contained more plastics (up to 30.2% by weight), were coarser-grained, and were more permeable (t-test, p < 0.0001). 85% of the fragments were polyethylene, and 95% were concentrated in the top 15 cm of the cores. We constructed artificial cores of standardized grain size and varying plastic-to-sediment ratios. Adding plastic significantly increased the permeability (ANOVA, p = 0.002), which was partially attributed to the fragments increasing the mean grain size. Sediments with plastic warmed more slowly (16% maximum decrease in thermal diffusivity), and reached lower maximum temperatures (21% maximum increase in heat capacity). These changes have a variety of potential effects on beach organisms, including those with temperature-dependent sex-determination such as sea turtle eggs.     

Short-term variability of multiple biomarker response in fish from estuaries: Influence of environmental dynamics

Short-term variability in biomarker responses and the effects of temperature and salinity variation were explored in three fish species (Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps) occurring in the Tejo estuary. Short-term variability in biomarkers was observed in all species although no pattern was discerned over time (days to weeks). Antioxidant enzymes activity (superoxide dismutase (SOD) and catalase (CAT)) showed low temporal variability, indicating some constancy or baseline level in antioxidant responses. Only CAT activity in S.?senegalensis was correlated with temperature, suggesting that exposure to contaminants triggered antioxidant acclimation. Higher short-term variability was observed in xenobiotic biotransformation enzymes activity (phase I ethoxyresorufin O-deethylase (EROD) and phase II glutathione S-transferase (GST)). Yet a significant correlation between EROD and GST in D.?labrax and S.?senegalensis suggests a concomitant response to contaminants. Moreover the lack of correlation between xenobiotic biotransformation enzymes and abiotic variables on concordant time scales, suggest a high specificity of these biomarkers to chemical exposure, rather than high variability due to environmental dynamics.     

太阳色球细节放大像

本文简述了利用小口径太阳色球望远镜,拍取色球细节照片,其分辨率可达1.5″的方法。