Biodiversity defrosted : unveiling non-compliant fish trade in ethnic food stores

Out of nearly 30,000 teleosts dwelling in our planet’s water bodies, only hundreds of them are commercially exploited and prevail on the global food market. Yet, our estimates of the species actually underpinning global trade is severely hampered by inaccuracy and non-compliance in labelling and reporting. Here, we target ethnic food stores in two British cities (Liverpool and Manchester metropolitan areas), whose numbers are increasing throughout Europe, to examine accuracy of traceability information available to consumers. Despite the existence of thorough EU labelling regulations, we unveil a high level of non-compliance, with a diverse range of poorly-known fish species, often sold without any label, or with erroneous information, as demonstrated by DNA barcoding. Results indicate that about 41% of the samples were mislabelled, in stark contrast with a recent study that, in 2015, found less than 5% mislabelling in EU supermarkets and fishmongers. These results highlight that inspectors and governments might not be fully aware of the wide diversity of fish species traded, indicating the need for a stronger enforcement of the EU labelling legislations. Compliance with regulations is required not only to protect consumers, but also fish stocks, as for many of the species identified in this survey, population assessment is poor or lacking altogether

Isotopic Overlap of Invasive and Native Consumers in the Food Web of Lake Trasimeno (Central Italy)

An advanced characterization of the trophic niche of non-indigenous species (NIS) may provide useful information on their ecological impact on invaded communities. Here, we used carbon and nitrogen stable isotopes to estimate pairwise niche overlaps between non-indigenous and native consumers in the winter food web of Lake Trasimeno (central Italy). Overall, a relatively low pairwise overlap of isotopic niches was observed between NIS and native species. The only exception was the Louisiana crayfish Procambarus clarkii, which showed a relatively high and diffuse overlap with other native invertebrates. Our findings highlighted a high niche divergence between non-indigenous and native species in Lake Trasimeno, suggesting a potentially low degree of interspecific competition that may facilitate coexistence and, in turn, limit the strength of impacts. The divergent results obtained for the Louisiana crayfish indicate that additional control measures for this invasive species are needed to mitigate its impact on the Lake Trasimeno system

Limited dispersion and quick degradation of environmental DNA in fish ponds inferred by metabarcoding

Background Environmental DNA (eDNA) metabarcoding is a promising tool for rapid, non‐invasive biodiversity monitoring. Aims In this study, eDNA metabarcoding is applied to explore the spatial and temporal distribution of fish communities in two aquaculture ponds and to evaluate the detection sensitivity of this tool for low‐density species alongside highly abundant species. Materials & Methods This study was carried out at two artificially stocked ponds with a high fish density following the introduction and removal of two rare fish species. Results & Discussion When two rare species were introduced and kept at a fixed location in the ponds, eDNA concentration (i.e., proportional read counts abundance) of the introduced species typically peaked after two days. The increase in eDNA concentration of the introduced fish after 43 hrs may have been caused by increased eDNA shedding rates as a result of fish being stressed by handling, as observed in other studies. Thereafter, it gradually declined and stabilised after six days. These findings are supported by the highest community dissimilarity of different sampling positions being observed on the second day after introduction, which then gradually decreased over time. On the sixth day, there was no longer a significant difference in community dissimilarity between sampling days. The introduced species were no longer detected at any sampling positions on 48 hrs after removal from the ponds. eDNA is found to decay faster in the field than in controlled conditions, which can be attributed to the complex effects of environmental conditions on eDNA persistence or resulting in the vertical transport of intracellular DNA and the extracellular DNA absorbed by particles in the sediment. The eDNA signal and detection probability of the introduced species were strongest near the keepnets, resulting in the highest community variance of different sampling events at this position. Thereafter, the eDNA signal significantly decreased with increasing distance, although the signal increased slightly again at 85 m position away from the keepnets. Conclusions Collectively, these findings reveal that eDNA distribution in lentic ecosystems is highly localised in space and time, which adds to the growing weight of evidence that eDNA signal provides a good approximation of the presence and distribution of species in ponds. Moreover, eDNA metabarcoding is a powerful tool for detection of rare species alongside more abundant species due to the use of generic PCR primers, and can enable monitoring of spatial and temporal community variance

Mapping biodiversity hotspots of fish communities in subtropical streams through environmental DNA.

Large tropical and subtropical rivers are among the most biodiverse ecosystems worldwide, but also suffer from high anthropogenic pressures. These rivers are hitherto subject to little or no routine biomonitoring, which would be essential for identification of conservation areas of high importance. Here, we use a single environmental DNA multi-site sampling campaign across the 200,000 km2 Chao Phraya river basin, Thailand, to provide key information on fish diversity. We found a total of 108 fish taxa and identified key biodiversity patterns within the river network. By using hierarchical clustering, we grouped the fish communities of all sites across the catchment into distinct clusters. The clusters not only accurately matched the topology of the river network, but also revealed distinct groups of sites enabling informed conservation measures. Our study reveals novel opportunities of large-scale monitoring via eDNA to identify relevant areas within whole river catchments for conservation and habitat protection

Sushi barcoding in the UK : another kettle of fish

Although the spread of sushi restaurants in the European Union and United States is a relatively new phenomenon, they have rapidly become among the most popular food services globally. Recent studies indicate that they can be associated with very high levels (>70%) of fish species substitution. Based on indications that the European seafood retail sector may currently be under better control than its North American counterpart, here we investigated levels of seafood labelling accuracy in sushi bars and restaurants across England. We used the COI barcoding gene to screen samples of tuna, eel, and a variety of other products characterised by less visually distinctive `white flesh'. Moderate levels of substitution were found (10%), significantly lower than observed in North America, which lends support to the argument that public awareness, policy and governance of seafood labels is more effective in the European Union. Nevertheless, the results highlight that current labelling practice in UK restaurants lags behind the level of detail implemented in the retail sector, which hinders consumer choice, with potentially damaging economic, health and environmental consequences. Specifically, critically endangered species of tuna and eel continue to be sold without adequate information to consumers

Terrestrial land cover shapes fish diversity in major subtropical rivers

Freshwater biodiversity is critically affected by human modifications of terrestrial land use and land cover (LULC). Yet, knowledge of the spatial extent and magnitude of LULC-aquatic biodiversity linkages is still surprisingly limited, impeding the implementation of optimal management strategies. Here, we compiled fish diversity data across a 160,000-km² subtropical river catchment in Thailand characterized by exceptional biodiversity yet intense anthropogenic alterations, and attributed fish species richness and community composition to contemporary terrestrial LULC across the catchment. We estimated a spatial range of LULC effects extending up to about 20 km upstream from sampling sites, and explained nearly 60% of the variance in the observed species richness, associated with major LULC categories including croplands, forest, and urban areas. We find that integrating both spatial range and magnitudes of LULC effects is needed to accurately predict fish species richness. Further, projected LULC changes showcase future gains and losses of fish species richness across the river network and offer a scalable basis for riverine biodiversity conservation and land management, allowing for potential mitigation of biodiversity loss in highly diverse yet data-deficient tropical to sub-tropical riverine habitats

Silicon photonics in Pirelli

Silicon is the dominant material in the microelectronic industry and silicon photonics is rapidly gaining importance as a technological platform for a wide range of applications in telecom, and optical interconnect. It allows the implementation of many photonic functions through the use of wafer-scale technologies normally used for advanced CMOS-processing. In this paper some of the most important issues toward a practical implementation of Silicon photonics into an industrial device will be addressed: low loss waveguides, polarization handling, tunability, hitless switching. A tunable Add-Drop multiplexer has been chosen as a case Study of a fully integrated device

Isotopic Niche and Trophic Position of the Invasive Portunid Portunus segnis Forskål, (1775) in Elounda Bay (Crete Island, Eastern Mediterranean)

There is a growing recognition that an advanced understanding of the trophic characteristics of an invasive consumer can provide important information on its ecological impact. In recent years, the blue swimming crab Portunus segnis, one of the earliest Lessepsian invaders, has considerably expanded its distribution range in the Mediterranean Sea, yet, its trophic habits in invaded areas remain scarcely investigated. In this study, we used carbon and nitrogen stable isotopes analysis (SIA) to determine the trophic position and isotopic niche of the crab compared with other representatives of the flora and fauna occurring in Elounda Bay (Crete). P. segnis showed a trophic position of 3.9, higher than the values determined by SIA or conventional gut content analysis in other areas of the Mediterranean Sea or in the native range. Crab specimens showed a high inter-individual variability in both delta C-13 and delta N-15 values; further analysis indicated negligible differences in the isotopic niche of adult males and females. Conversely, delta N-15 values were significantly related to the size of the specimens, ultimately suggesting an ontogenetic dietary shift. This study represents the first attempt to characterize the trophic habits of the blue swimming crab in the context of an invaded food web and may contribute to the implementation of long-term management strategies of control and mitigation of its ecological impact