Exposure of mediterranean countries to ocean acidification

This study examines the potential effects of ocean acidification on countries and fisheries of the Mediterranean Sea. The implications for seafood security and supply are evaluated by examining the sensitivity of the Mediterranean to ocean acidification at chemical, biological, and macro-economic levels. The limited information available on impacts of ocean acidification on harvested (industrial, recreational, and artisanal fishing) and cultured species (aquaculture) prevents any biological impact assessment. However, it appears that non-developed nations around the Mediterranean, particularly those for which fisheries are increasing, yet rely heavily on artisanal fleets, are most greatly exposed to socioeconomic consequences from ocean acidification. © 2014 by the authors; licensee MDPI, Basel, Switzerland

Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions

An experimental study of ²²⁶Ra and ⁴⁵Ca accumulation from the aquatic medium by freshwater turtles (fam. Chelidae) under varying Ca and Mg water concentrations

Snapping turtles Elseya dentata (Gray) from Magela Creek, Northern Territory, were exposed under laboratory conditions for up to 30 days to waters resembling the inorganic composition of Magela Creek water during the Wet season, with background and elevated Ca and Mg concentrations, that were labelled with 226Ra and 45Ca. The resulting concentrations of 45Ca in muscle, skin, gut, liver, shell bone and leg bone of E. dentata equilibrated or approached equilibrium by 12-18 days. Among the experiments, the concentrations of 45Ca in all six tissues were inversely related to turtle mass. An increase in the Ca water concentration by a factor of 15 increased the 45Ca concentration in all six tissues. The arithmetic factors of increase in the concentration in each tissue were proportional or more than proportional to the factor of increase in Ca water concentration; this factor was highest for muscle tissue (26.6). An increase in the Mg water concentration by a factor of 48 reduced the 45Ca concentration in all tissues except skin where it increased. The concentration of 226Ra in each tissue (except the gut) was positively related to its 45Ca concentration and inversely related to turtle mass in muscle, skin and liver. With the exception of the skin, the increased Ca water concentration did not reduce the 226Ra in the tissues but increased the 226Ra concentration in bone and muscle. The increased Mg water concentration had an inverse effect on the 226Ra concentrations in all tissues except shell. With the exception of the skin the effects of increased Ca and Mg water concentrations and turtle size on 226Ra concentrations in the tissues of E. dentata were similar to their effects on 45Ca tissue concentrations, indicating the similar metabolic behaviour of 226Ra and 45Ca in E. dentata. Exposures of the species Elseya latisternum (Gray), Emydura signata (Ahl) and Chelodina longicollis (Shaw), which are the same or closely related to species reported to occur in Magela Creek, to 45Ca-labelled Sydney tap water for 7 days demonstrated their ability to also accumulate 45Ca from their aquatic medium. The patterns of 45Ca concentrations in the tissues of these species indicated that they were inversely related to turtle mass, as demonstrated in E. dentata. The concentrations of 45Ca accumulated in the tissues were also comparable to those found in single specimens of E. dentata and E. victoriae (Gray) that were exposed for 7 days to simulated Magela Creek water. The data also indicated the larger long-necked C. longicollis accumulated less 45Ca per gram of tissue than similar-sized, short-necked species E. signata and E. latisternum, suggesting that long-necked turtles from Magela Creek would accumulate less 226Ra from their aquatic medium than similar-sized short-necked species. The capacity of E. dentata to accumulate 226Ra from the aquatic medium is about two orders of magnitude less than that of the tissue of the freshwater mussel Velesunio angasi (Sowerby) exposed under similar experimental conditions. © 1991 Kluwer Academic Publishers

Experimental comparison of the bioaccumulation of anthropogenic radionuclides by egg and juvenile life stages of a small shark

© 2017 Elsevier Ltd This study compared the bioaccumulation of anthropogenic nuclides (65Zn, 134Cs, 60Co and 241Am) between the egg and juvenile life stages of a small shark (Scyliorhinus canicula), based on previously published experimental data. Rates of accumulation over 15 days were derived and summed for the transfer pathways which were specific to these two life stages. Radionuclide transfers to the egg and its embryo & yolk were quantified for i) the maternal pathway following her uptake of radionuclides via food and seawater and ii) from seawater following its oviposition. For the juvenile, the transfer of radionuclides were measured for aqueous & dietary pathways. The results show that, compared to juveniles, eggs have equivalent rates of accumulation of 65Zn and 134Cs but enhanced accumulation of 241Am by a factor of five and of 60Co by two orders of magnitude. The radiological exposure of the embryo due to radionuclides maternally transferred to the embryo & yolk is also enhanced for the alpha-emitting 241Am. This enhanced accumulation of 241Am and 60Co, as well as the equivalent accumulation of 65Zn and 134Cs, suggest greater likely vulnerability to radiation damage in eggs as compared to juveniles. Radiological dose assessment confirmed highest doses to the egg which is predominantly due to accumulated 241Am

The Finniss River: a natural laboratory of mining impact- past present and future.

The Rum Jungle uranium-copper mine in tropical northern Australia has been a source of acid rock drainage contaminants since the 1950s which have had adverse impacts on the receiving waters of the Finniss River. Mine site remediation began in 1982 followed by long-term monitoring of water quality and flow based on daily measurements within the Finniss River system. A decade or more after the initiation of these remedial activities a set of investigations have been completed that have measured the post-remedial ecological status of the Finniss River system relative to this environmental benchmark. These studies have also been complemented by studies on various other ecological endpoints. Moreover the Finniss River system has provided unique opportunities for broader scientific goals to be pursued. Because it has been so well-monitored it can be viewed as a natural laboratory to investigate the impacts of acid rock drainage on tropical freshwater biodiversity. The scientific papers presented at this symposium address a broad spectrum of issues that are directly related to environmental sustainability and mining. The topics range across future contaminant scenarios and their predicted ecological impacts the various metrics used to assess ecological detriment to biodiversity the abilities of laminated biological structures to act as archives of pollution history and also spin-off applications in environmental and wildlife management. Furthermore the participation of many stakeholders in open discussion during the symposium provided an important set of views and opinions on the needs for future studies in the Finniss River system

Accumulation of Radiocalcium From the Aquatic Medium Via the Cloaca and Bucco-Pharynx of Australian Fresh-Water Turtles (chelidae)

1. The cloacal and bucco-pharyngeal regions of three species of Australian freshwater turtles were experimentally compared for their ability to take up radiocalcium directly from the aquatic medium

Diminished metal accumulation in riverine fishes exposed to acid mine drainage over five decades

Bony bream (Nematalosa erebi) and black catfish (Neosilurus ater) were sampled from the fresh surface waters of the Finniss River in tropical northern Australia, along a metal pollution gradient draining the Rum Jungle copper/uranium mine, a contaminant source for over five decades. Paradoxically, populations of both fish species exposed to the highest concentrations of mine-related metals (cobalt, copper, lead, manganese, nickel, uranium and zinc) in surface water and sediment had the lowest tissue (bone, liver and muscle) concentrations of these metals. The degree of reduction in tissue concentrations of exposed populations was also specific to each metal and inversely related to its degree of environmental increase above background. Several explanations for diminished metal bioaccumulation in fishes from the contaminated region were evaluated. Geochemical speciation modeling of metal bioavailability in surface water showed no differences between the contaminated region and the control sites. Also, the macro-nutrient (calcium, magnesium and sodium) water concentrations, that may competitively inhibit metal uptake, were not elevated with trace metal contamination. Reduced exposure to contaminants due to avoidance behavior was unlikely due to the absence of refugial water bodies with the requisite metal concentrations lower than the control sites and very reduced connectivity at time of sampling. The most plausible interpretation of these results is that populations of both fish species have modified kinetics within their metal bioaccumulation physiology, via adaptation or tolerance responses, to reduce their body burdens of metals. This hypothesis is consistent with (i) reduced tissue concentrations of calcium, magnesium and sodium (macro-nutrients), in exposed populations of both species, (ii) experimental findings for other fish species from the Finniss River and other contaminated regions, and (iii) the number of generations exposed to likely selection pressure over 50 years. © 2014 Jeffree et al