IN THIS ISSUE Bruce Osborne Going with the flow? Over the years there has been much discussion about the impact of agricultural practices on nutrient losses from farmland and how this contributes to the eutrophication of water bodies. One of the continuing challenges is to ensure that agricultural practices are sustainable and have little impact on the environment. Although often seen as being onerous for the farmer, reducing any nutrient losses could be beneficial by reducing the inputs of fertiliser that are required to support crop yields, thereby representing a win-win situation. Rather surprisingly, however, the pathways and magnitude of any nutrient losses from cropland in Ireland have been poorly quantified. The often-assumed notion is that soil disturbance through tillage results in the greater run off of nutrients such as phosphorus (P) and nitrogen, giving rise to an increased emphasis on minimum or conservation tillage practices. Ryan and Finnan, in this issue, show, however, that for tillage operations associated with grey podsolic soils that cover around 16% of the total agricultural area, P losses through overland flow are small, despite presumably being associated with high P inputs, and therefore are unlikely to represent a significant pollution threat. Whilst these findings are welcome, we should not be over-confident of their widespread applicability to all soil types. Also, nutrient losses can show considerable spatial variability, making an accurate assessment of any losses very challenging; further assessment and quantification of the pathways involved is clearly required. Fishing for the future The impact of declining fish stocks and the consequences for biodiversity, ecosystem services and livelihoods has been well documented. The assessment of fish stocks or any change in fish stocks due to management factors or natural drivers is, however, clearly very difficult for a number of logistical and practical reasons. The use of genetic markers, such as microsatellites, holds some promise in providing a more accurate picture of fish populations and for the assessment of the reason(s) behind any decline in stocks. Using thirteen microsatellite markers, Bozano et al., in this issue, assessed variability in the population structure of horse mackerel (Trachurus trachurus) in the North-east Atlantic. Their results indicated a relatively stable population of horse mackerel towards the west of Ireland, with variable connectivity with those populations found in Norwegian waters. Importantly, unstable inter-annual variations in the genetic patterns found to the west of Norway were explained by changes in nutrient transport and variations in ocean currents that could clearly have an impact on long-term fish stocks. Separating out the impacts on fish stocks caused by man from those due to naturally occurring events represents a considerable challenge, but doing so will be necessary to ensure the effective management and protection of our fisheries resource and their sustainable exploitation well into the future. Riparian buffer zone refugia? Research on riparian buffer zones as a means of reducing the environmental impacts of different land management practices associated with agriculture or afforestation on river biota, in particular, has been a recurring theme in Biology and Environment. As well as a potential environmental ‘protective’ role, riparian buffer zones could also provide a range of ecosystem services and biodiversity benefits, including by acting as refugia for species with a high conservation value, in an otherwise environmentally -impoverished and biodiversity-poor landscape. Assessments by Madden et al., in this issue, of the plants, spiders and beetles associated with fenced riparian zones, including grassland, scrub and woodland vegetation associated with intensively managed grassland ecosystems, revealed distinct assemblages of plants and spiders, but not carabid beetles. Abundance and richness varied according to vegetation type, with more spiders and carabids in grassland areas, while the greatest regional richness of carabids was found in scrub-dominated margins. Perhaps rather surprisingly, these zones had a low incidence of specialised flora and fauna, probably reflecting in part a dependence on local diversity and dispersal, but the incidences were low even when compared to findings from similar studies or data from national records. These authors suggest that further investigation of the appropriate management interventions to be used, allowing limited grazing, for instance, might increase the abundance and/or richness of some taxonomic groups and further improve the...
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Oct 12, 2019
Hua Wang + 5
Open Access