No abstract

Integrated Constructed Wetlands (ICWs) constitute an alternative way of cleansing water in agricultural areas to conventional water treatment plants. These pond systems integrate their water treatment capabilities with other functions such as biodiversity enhancement, carbon sequestration and landscape fit, by virtue of mimicking natural wetlands. ICWs have shown to have potential to enhance macroinvertebrate diversity in agricultural areas due to their unique design flexibility. We suggest that ICWs characterised by adequate shore sloping and presence of complex habitat mosaics, as well as other design considerations, would maximise the potential of these systems to enhance macroinvertebrate diversity. In addition, it would be highly beneficial to increase the total ICW area and to increase the total number of ponds in a system accordingly from a minimum of four to at least five. This article also highlights the need not only to develop policies that focus on the creation of ICWs but also to foster a number of management practices that rely on the active involvement of farmers. The inclusion of additional ponds in selected ICW systems could be the means to inform local communities as to the importance, attractiveness and conservation value of ponds.

This study is the first comprehensive documentation of the geographical range of Anguillicola crassus in its host, the European eel Anguilla anguilla, in the Republic of Ireland. The prevalence and intensity of infections across 234 sites and 93 river basins in Ireland comprising rivers, lakes and transitional waters (estuaries) were analysed. While only 32% of the river basins were affected by this nematode, they correspond to 74% of the total wetted area. Significant differences in infection levels among water body types were found with lakes and transitional waters yielding the highest values, which can be attributed to the proportions of juvenile (total length, L(T) < 300 mm) A. anguilla caught. There were no significant differences in infection levels between water body types for adult A. anguilla or between sexes for any water body type. Prevalence was significantly lower in juvenile compared with adult A. anguilla captured in rivers and a positive correlation between infection levels and host size-classes was found. Future efforts should focus on monitoring the spread of A. crassus infections and assessing the swimbladder health of A. anguilla in Ireland.

Highlights • Among 482 eels, 66% were impacted by A. crassus and 27% showed evidence of past infection. • Among 169 eels, organic and inorganic contaminants showed high prevalence. • Variability in eel quality at the European scale was mainly driven by organic pollutants. • According a risk index, eels from Scheldt, Warwickshire and Frémur ranked lowest risk. • Eel quality risks were positively correlated with a remote sensing anthropization index.