Occurrence and distribution of polybrominated diphenyl ethers (PBDEs) in the dissolved and suspended phases of the sea-surface microlayer and seawater in Hong Kong, China

This study reports the first data on the concentration and distribution of polybrominated diphenyl ethers (PBDEs) in the sea-surface microlayer (SML), and their enrichment relative to bulk seawater, for coastal waters in the marine environment of Hong Kong, China. Samples were collected in March 2005 at five sample locations and analysed for eight congeners of primary interest, i.e. BDE 28, 47, 99, 100, 153, 156, 183 and 209. Concentration ranges of summation operatorPBDE in the dissolved phase (DP, defined as sum of truly dissolved and colloidal phase) and suspended particulate matter (SPM) of seawater were 31.1-118.7 pg/l (mean 70.7 pg/l), and 25.7-32.5 pg/l (mean 28.1 pg/l), respectively. Concentrations in the SML were generally higher by factor of 1.3-3.6 in the DP (concentration range from 40.2 to 228.2 pg/l, mean 149.2 pg/l) and by 0.3-2.1 in the SPM (concentration range 8.1-69.1 pg/l, mean 38.2 pg/l). Concentrations of PBDEs were general low and below detection limits in samples of an oceanic character and highest in the sheltered waters of Victoria Harbour. The congeners BDE 28, 47, 100 and 183 were most abundant, where BDE 209 was detected only in trace amounts. It is suggested that Hong Kong's marine waters show relatively low levels of PBDE contamination, and these compounds may originate from the disposal of electronic waste in southern China, as well as untreated discharge of wastewater locally.     

Evaluation of a biomarker of Cd(II) exposure on Limnoperna fortunei

The use of organisms to monitor contamination allows the access to information that cannot be acquired by chemical methods. Limnoperna fortunei, mussel frequently found in Río de la Plata estuary, fulfils the requirements to be used as a biomonitoring organism. In this work we report that a polypeptide of 22 kDa of molecular weight (LF22) is induced when L. fortunei is exposed to Cd (II), Cu(II) and Hg(II) sublethal levels. To characterize LF22, mussels were sampled from a non-polluted region and whole soft tissue was homogenized, with and without previous exposure to 100 microg/L of Cd(II). The cytosolic proteins were evaluated by mono and bidimensional SDS-PAGE, and size exclusion chromatography. All the methods showed that LF22 triples its concentration in presence of Cd(II). Purification of LF22 was achieved by fractioned precipitation, salting-out, ionic exchange and size exclusion chromatography. We conclude that LF22 is a useful biomarker of heavy metal exposure.     

Large-eddy simulation of starting buoyant jets

A series of Large Eddy Simulations (LES) are performed to investigate the penetration of starting buoyant jets. The LES code is first validated by comparing simulation results with existing experimental data for both steady and starting pure jets and lazy plumes. The centerline decay and the growth rate of the velocity and concentration fields for steady jets and plumes, as well as the simulated transient penetration rate of a starting pure jet and a starting lazy plume, are found to compare well with the experiments. After validation, the LES code is used to study the penetration of starting buoyant jets with three different Reynolds numbers from 2000 to 3000, and with a wide range of buoyancy fluxes from pure jets to lazy plumes. The penetration rate is found to increase with an increasing buoyancy flux. It is also observed that, in the initial Period of Flow Development, the two penetrative mechanisms driven by the initial buoyancy and momentum fluxes are uncoupled; therefore the total penetration rate can be resolved as the linear addition of these two effects. A fitting equation is proposed to predict the penetration rate by combining the two independent mechanisms.     

Factors influencing survival duration and choice of virgin queens in the stingless bee Melipona quadrifasciata

In Melipona quadrifasciata, about 10 % of the females develop into queens, almost all of which are killed. Occasionally, a new queen replaces or supersedes the mother queen or heads a new colony. We investigated virgin queen fate in queenright and queenless colonies to determine the effects of queen behaviour, body mass, nestmate or non-nestmate status, queenright or queenless colony status, and, when queenless, the effect of the time a colony had been queenless, on survival duration and acceptance. None of 220 virgin queens observed in four observation hives ever attacked another virgin queen nor did any of 88 virgin queens introduced into queenright colonies ever attack the resident queen. A new queen was only accepted in a queenless colony. Factors increasing survival duration and acceptance of virgin queens were to emerge from its cell at 2 h of queenlessness, to hide, and to avoid fights with workers. In this way, a virgin queen was more likely to be available when a colony chooses a new queen, 24-48 h after resident queen removal. Running, walking or resting, antennating or trophallaxis, played little or no role, as did the factors body mass or nestmate. “Queen choice” took about 2 h during which time other virgin queens were still being killed by workers. During this agitated process, the bees congregated around the new queen. She inflated her abdomen and some of the workers deposited a substance on internal nest surfaces including the glass lid of the observation hive.     

A guide to using the internet to monitor and quantify the wildlife trade

The unrivaled growth in e-commerce of animals and plants presents an unprecedented opportunity to monitor wildlife trade to inform conservation, biosecurity, and law enforcement. Using the internet to quantify the scale of the wildlife trade (volume and frequency) is a relatively recent and rapidly developing approach that lacks an accessible framework for locating relevant websites and collecting data. We produced an accessible guide for internet-based wildlife trade surveillance. We detailed a repeatable method involving a systematic internet search, with search engines, to locate relevant websites and content. For data collection, we highlight web-scraping technology as an efficient way to collect data in an automated fashion at regularly timed intervals. Our guide is applicable to the multitude of trade-based contexts because researchers can tailor search keywords for specific taxa or derived products and locations of interest. We provide information for working with the diversity of websites used in wildlife trade. For example, to locate relevant content on social media (e.g., posts or groups), each social media platform should be examined individually via the site's internal search engine. A key advantage of using the internet to study wildlife trade is the relative ease of access to an increasing amount of trade-related data. However, not all wildlife trade occurs online and it may occur on unobservable sections of the internet.