Diets of fan shells (Pinna nobilis) of different sizes: fatty acid profiling of digestive gland and adductor muscle

Pinna nobilis is a large bivalve, endemic to the Mediterranean Sea that was shown in a previous study to ingest significantly different proportions of different food items according to its shell height. Fatty acid profiling of total lipids was used to examine these differences in diet in relation to shell size. Small (shell height 23.0 ± 3.3 cm), medium (SH 41.5 ± 5.5 cm) and large (SH 62.7 ± 4.8 cm) P. nobilis were collected from Mali Ston Bay, Adriatic Sea, in March 2010, and fatty acid analysis was performed on digestive gland and adductor muscle tissues. Based on the analysis of the digestive gland, small P. nobilis were associated with a detrital food chain, characterized by saturated and branched-chain fatty acids, while the diets of medium and large individuals had a greater proportion of polyunsaturated fatty acids. This likely reflects the fact that smaller individuals feed within the benthic boundary layer where the detritus concentrations are high. Fatty acid incorporation into the adductor muscle, likely representative of food taken up over a longer time period, was reversed, that is, larger individuals had lower levels of polyunsaturated fatty acids. This most probably reflects energy expenditure, which typically increases with increasing organism size.     

Millennium-old farm breeding of Chinese softshell turtles (<Emphasis Type="Italic">Pelodiscus</Emphasis> spp.) results in massive erosion of biodiversity

Chinese softshell turtles (Pelodiscus spp.) are widely distributed, ranging from the Amur and Ussuri Rivers in the Russian Far East through the Korean Peninsula, Japan, and eastern, central, and southern China to southern Vietnam. In East and Southeast Asia, Chinese softshell turtles are traditionally exploited for food and have been farm-bred in China since the Spring and Autumn Period, more than 2400 years ago. Currently, the annual production of Pelodiscus amounts to 340,000 t in China alone. Using mitochondrial DNA (2428 bp) and five nuclear loci (3704 bp), we examined broad sampling of wild and farm-bred Pelodiscus to infer genetic and taxonomic differentiation. We discovered four previously unknown mitochondrial lineages, all from China. One lineage from Jiangxi is deeply divergent and sister to the mitochondrial lineage of Pelodiscus axenaria. The nuclear loci supported species status for P. axenaria and the new lineage from Jiangxi. Pelodiscus maackii and P. parviformis, both harboring distinct mitochondrial lineages, were not differentiated from P. sinensis in the studied nuclear markers. The same is true for two new mitochondrial lineages from Zhejiang, China, represented by only one individual each, and another new lineage from Anhui, Guangdong, Jiangxi and Zhejiang, China. However, Vietnamese turtles yielding a mitochondrial lineage clustering within P. sinensis were distinct in nuclear markers, suggesting that these populations could represent another unknown species with introgressed mitochondria. Its species status is also supported by the syntopic occurrence with P. sinensis in northern Vietnam and by morphology. In addition, we confirmed sympatry of P. axenaria and P. parviformis in Guangxi, China, and found evidence for sympatry of P. sinensis and the new putative species from Jiangxi, China. We also discovered evidence for hybridization in turtle farms and for the occurrence of alien lineages in the wild (Zhejiang, China), highlighting the risk of genetic pollution of native stock. In the face of the large-scale breeding of Pelodiscus, we claim that the long-term survival of distinct genetic lineages and species can only be assured when an upscale market segment for pure-bred softshell turtles is established, making the breeding of pure lineages lucrative for turtle farms. Our findings underline that the diversity of Pelodiscus is currently underestimated and threatened by anthropogenic admixture. We recommend mass screening of genetic and morphological variation of Chinese softshell turtles as a first step to understand and preserve their diversity.     

Sulphurous air pollutants and exposure events of workers in thermal-mineral springs: a case study of Contursi Terme (Salerno,Italy)

Environmental Science and Pollution Research - Thermo-mineral springs are widely spread over the volcanic areas of Salerno, a city in southern Italy. Although the water of thermal structures...     

Experimental prey species preferences of Hexaplex trunculus (Gastropoda: Muricidae) and predator–prey interactions with the Black mussel Mytilus galloprovincialis (Bivalvia: Mytilidae)

Hexaplex trunculus is one of the most widespread Mediterranean species of muricid gastropod and lives on rocky, sandy-mud and mud substrata. Although common in the Adriatic Sea, relatively little is known about its ecology especially feeding behaviour. The aim of this study was to explore the aspects of the feeding behaviour of H. trunculus using Arca noae, Modiolus barbatus and Mytilus galloprovincialis as experimental prey. Prey species preference, predator size, prey size choice, feeding rates, handling times and mode and place of attack were analysed. Typically, only M. galloprovincialis was attacked: A. noae rarely at the byssal gape and M. barbatus never. Small (40 mm) H. trunculus could not easily attack large M. galloprovincialis (65 mm) and preferred small (20 mm) and medium (35 mm) sized prey. Conversely, medium (55 mm) and large (70 mm) H. trunculus fed randomly on M. galloprovincialis of all three sizes. The feeding strategy adopted by H. trunculus individuals varied with respect to size. A tendency to drill the prey shell was recorded for small predators, whereas marginal chipping was adopted more frequently by large individuals. On average small, medium and large H. trunculus consumed 2.4±1.6 (range 0–4), 1.2±1.6 (range 0–4) and 2.0±2.1 (range 0–6) M. galloprovincialis, respectively. There was a statistically significant difference in prey-handling time with respect to the method of access adopted, predator and prey sizes. The time required to access a M. galloprovincialis individual by marginal chipping was considerably less than that required for drilling. H. trunculus consumed an average of 0.60±0.80 g M. galloprovincialis tissue dry weight over a 5-week period, that is, ~40% of its own tissue body weight. This translates to an average-sized (55 mm shell height) H. trunculus consuming ~18 M. galloprovincialis of 50 mm shell length (minimum marketable size) per year. H. trunculus showed no preference to drill either the left or right valves of M. galloprovincialis but generally attacked the posterior shell margin.     

New evidences for old biomarkers: effects of several xenobiotics on EROD and AChE activities in Zebra mussel (Dreissena polymorpha)

The biomarker approach is widely used both in vertebrates and invertebrates for environmental biomonitoring, because it can supply an integrated response for multi-xenobiotics contamination. However, the use of biomarkers requires the identification of every possible variation that can influence the biochemical response, because ecosystems are generally subject to a mixture of pollutants, which can create additive, opposite or competitive effects. In recent years, there has been considerable interest in the use of biomarkers within marine bivalves, while very few data are available for freshwater molluscs. The aim of this research was to investigate changes on EROD and AChE activities in the freshwater bivalve Zebra mussel (Dreissena polymorpha) exposed to different pollutants (Arochlor 1260, CB 153 and 126, pp'DDT, chlorpyrifos, carbaryl) at laboratory conditions, in order to standardize the analytical procedures and to highlight eventual interferences on enzyme activities. Chemical concentrations in the mussel soft tissues were analyzed by GC/MS-MS. Main results showed a significant induction of EROD activity when mussels were exposed to 100 ng/l of PCB mixture of Arochlor 1260 and dioxin-like CB 126, but this congener showed also a clear competitive inhibition after 48 h of exposure. Surprisingly, pp'DDT determined a significant decrease of basal EROD activity after only 24 h of exposure, even if it was not possible to discriminate between the effect of the parent compound and that of its metabolites (DDD, DDE). We also found an interaction between the organophosphate insecticide chlorpyrifos, which does not directly decrease the AChE activity, and terbutilazine. This herbicide increased the biotransformation of the organophosphate compound to its oxidized metabolite (oxon), a much stronger AChE inhibitor. The possible use of the oxime Pyridine-2-Aldoxime Methochloride (2-PAM) to bring back the catalytic activity to basal levels was also demonstrated.     

Invasion costs,impacts, and human agency: response to Sagoff 2020

Article impact statement: In an era of profound biodiversity crisis, invasion costs, invader impacts, and human agency should not be dismissed.     

Assessment of flood-induced changes of phytoplankton along a river–floodplain system using the morpho-functional approach

In this research, we aimed to find out how the differences in hydrological connectivity between the main river channel and adjacent floodplain influence the changes in phytoplankton community structure along a river–floodplain system. The research was performed in the River Danube floodplain (Croatian river section) in the period 2008–2009 characterised by different flooding pattern on an annual time scale. By utilising the morpho-functional approach and multivariate analyses, the flood-derived structural changes of phytoplankton were analysed. The lake stability during the isolation phase triggered the specific pattern of morpho-functional groups (MFG) which were characterised by cyanobacterial species achieving very high biomass. Adversely, the high water turbulence in the lake during the frequent and extreme flooding led to evident similarity between lake and river assemblages. Besides different diatom species (groups of small and large centrics and pennates), which are the most abundant representatives in the river phytoplankton, many other groups such as cryptophytes and colonial phytomonads appeared to indicate altered conditions in the floodplain driven by flooding. Having different functional properties, small centric diatom taxa sorted to only one MFG cannot clearly reflect environmental changes that are shown by the species-level pattern. Disadvantages in using the MFG approach highlight that it is still necessary to combine it with taxonomical approach in monitoring of phytoplankton in the river–floodplain ecosystems.     

PCDDs/PCDFs in ambient air (<1 fg m(-3)) - the CTDEP long term sampling (30 d) method

The Connecticut Department of Environmental Protection (CTDEP) commenced monitoring for PCDDs/PCDFs (polychlorinated dibenzodioxins and polychlorinated dibenzofurans) in ambient air in 1987 and adopted the long term (30 d) sampling approach in 1993. The CTDEP method represents the first use of isotopically labeled PCDDs/PCDFs as field surrogates to monitor the behavior of native PCDDs/PCDFs present in actual ambient air samples. This feature first introduced in 1987 was later adopted by US EPA in revisions to sampling methods for PCDDs/PCDFs in ambient air (EPA Method TO9A) as well as development of EPA Reference Method 23 for measurement of PCDDs/PCFDs in stationary source emissions. Results are provided here for a total of twenty-three (23) samples (reported as pairs) representing twelve (12) 30 d sampling events conducted at a site located in metropolitan Hartford CT. Samples were collected in winter months during calendar years 2002-2008. PCDDs/PCDFs concentration data (pg m⁻³) are reported as both congener sums (Cl₄-Cl₈) and 2378-substitued congeners. Total PCDDs/PCDFs concentrations for these twelve (12) sampling events ranged from 0.68 pg m⁻³ (2003) to 4.18 pg m⁻³ (2004) with a mean concentration of 2.04 pg m⁻³.Method performance was monitored through use of collocated samples, in field isotopically labeled compounds, isotopically labeled laboratory applied internal standards and field blank samples. Method performance consistently exceeded goals established in USEPA Method TO9A for these same parameters. Average recoveries of in field labeled PCDDs/PCDFs ranged from 97.5% to 104.2%. Average (mean) recoveries for each of the ten (10) isotopically labeled internal standards ranged from 77.0% (¹³C-OCDF) to 95.5% (¹³C-2,3,7,8-TCDF). Method precision defined as % RPD data for collocated sampler pairs ranged from 8% to 14% for PCDDs and from 5% to 12% for PCDFs. The mean RPD for all PCDDs/PCDFs combined is 9.6%. Field monitoring results demonstrate method sensitivity for all PCDDs/PCDFs congeners and 2378-substituted congeners to be well below concentrations typically found for these compounds in ambient air (all reported data represent measured concentrations). Quantities (pg) found in field blanks represent the major determinant to achieving further enhancements in method sensitivity for selected congeners (OCDD < 42 fg m⁻³; 1,2,3,4,6,7,8-HpCDD < 5.7 fg m⁻³; and 1,2,3,4,6,7,8-HpCDF < 2.1 fg m⁻³). The CTDEP method represents a highly sensitive and reliable technique for monitoring of PCDDs/PCDFs congeners and other persistent organic pollutants (POPs) at ultra trace levels in ambient air (fg m⁻³).