De Grave S.,University of Oxford |
Ashelby C.W.,APEM Ltd
Zootaxa | Year: 2013
Recent phylogenetic work (Ashelby et al., 2012) has demonstrated the need for a fresh appraisal of the systematic status of some Palaemoninae genera. In the present contribution the accumulated morphological as well as molecular evidence is reviewed. The genera Palaemonetes, Exopalaemon and Coutierella are demonstrated to be junior synonyms of Palaemon, which now contains 83 species. As a result of this systematic re-arrangement, two replacement names are needed. Palaemon kwantung nom. nov. now replaces Exopalaemon guangdongensis Guo, Wang and Zhang, 2005, nec Palaemon guangdongensis Liu, Liang and Yan, 1990. Palaemon mundusnovus nom. nov. is the replacement name for Palaemonetes intermedius Holthuis, 1949, nec Palaemon intermedius (Stimpson, 1860).Copyright © 2013 Magnolia Press.
Poole A.E.,University of Oxford |
Bradley D.,APEM Ltd |
Salazar R.,University of Oxford |
Macdonald D.W.,University of Oxford
Agriculture, Ecosystems and Environment | Year: 2013
Freshwater ecosystems deliver services that are crucial to human existence and well-being, yet, globally, their degradation has outpaced remedial management. Rivers can be subjected to a range of anthropogenic pressures and agricultural land use is one major cause of water pollution and habitat degradation in European rivers. The Water Framework Directive is a major legislative driver for good ecological status in Europe's rivers and in the UK; this has led to attempts to reduce the negative effects of agriculture on rivers through agri-environment schemes (AES). AES are funded from tax revenue and it is important that they are optimized to deliver measurable ecological improvements. The purpose of this paper is to assess the ecological effectiveness of AES in a lowland English river basin. We examined the effect of distance from river in optimizing AES for the biological heath and conservation value of rivers.We used aquatic macroinvertebrates as indicators of river health and conservation value, to assess the effects of AES likely to improve river health (hereafter "AES river options"). This catchment in lowland England had a very high (over 80%) level of uptake of entry level AES, and facilitated a comparison between schemes that do or do not contain AES river options. The conservation value of macroinvertebrate communities and the proportion of macroinvertebrates intolerant of water pollution and sedimentation increased with high proportions of woodland within 100. m or 500. m of the river throughout the entire upstream catchment. High proportions of AES river options within the same distance were correlated with higher proportions of sediment-sensitive macroinvertebrates. We conclude that for improving biological quality or promoting the conservation value of river communities, AES will be optimized by preserving woodland within a 100-500. m buffer zone along the upstream length of the river. © 2013 Elsevier B.V.
Lundholm N.,Copenhagen University |
Clarke A.,APEM Ltd |
Ellegaard M.,Copenhagen University
Harmful Algae | Year: 2010
We present a detailed record of shifts in species composition of the toxic diatom genus Pseudo-nitzschia from 1905 to 2001 in Mariager Fjord, Denmark, most probably driven by changes in nitrogen loading to the coastal environment and increasing temperatures in the sea. The fertile Mariager Fjord is a long narrow sill-fjord with a permanently anoxic basin. The fjord has experienced increased nutrient loading during the last 100 years and is presently highly eutrophic. 210Pb-dated sediment cores from the anoxic basin in Mariager Fjord were used in a palaeoecological study to explore changes in species composition. Within the genus Pseudo-nitzschia we observed a change in species composition where Pseudo-nitzschia multiseries was dominant before 1947, when a shift occurred towards dominance by Pseudo-nitzschia pungens. At the same time an increasing relative abundance of Pseudo-nitzschia seriata and Pseudo-nitzschia americana was observed. The increase in relative abundance of P. pungens was positively correlated to nitrogen loading and suggests that increased nitrogen loading during the last 100 years contributes to the observed shift. We hypothesise that increased water temperature in the area could also have contributed to the observed shift in species composition. Three of the species identified (P. heimii, P. americana, P. pseudodelicatissima) are new records for Denmark and Scandinavia. One of these species, P. americana, has been linked to increased ammonium concentrations. The preservation of the frustules was excellent and valves of Pseudo-nitzschia were identified to species level in sediment dating as far back as 7900 years before present. © 2010 Elsevier B.V.
Ruse L.,APEM Ltd
Fauna Norvegica | Year: 2010
An artificial anabranch was opened to the main River Thames by the end of 2001. Chironomid pupal exuviae have been sampled from sites along the main river since 1977 including sites above and below the anabranch. Two sites on the anabranch have also been surveyed since its opening. Long-term surveillance of the chironomid assemblage prior to construction of the anabranch provided a reference state by which its impact could be assessed. Feeding and habitat preferences were attributed to chironomid taxa while additional environmental -tolerance traits were derived from the long-term data of the Thames. Canonical Correspondence Analysis, with spatial variation partialled out, was used to select temporal environmental variables explaining chironomid taxa distribution. Taxa with significant t-values in the regression with selected environmental variables were then included in the subsequent analysis of variance of traits by General Linear Modelling. From 1977 up to 2001 lower Thames sites, above and below the anabranch, showed no significant changes in any of the traits investigated. Four surveys from 2002 to 2009 have revealed some significant changes downstream of the anabranch, both in comparison with before-construction and between sites. These changes suggest the anabranch is providing a sink for poor-quality sediments. Immediately downstream of the anabranch fine sediment-dwelling chironomids have declined within the Thames, chironomids sensitive to ammonia have increased while chironomids tolerant of organic pollution have decreased.
Aprahamian M.W.,UK Environment Agency |
Aprahamian C.D.,UK Environment Agency |
Knights A.M.,APEM Ltd |
Knights A.M.,University of Liverpool
Journal of Fish Biology | Year: 2010
A stock-recruitment model with a temperature component was used to estimate the effect of an increase in temperature predicted by climate change projections on population persistence and distribution of twaite shad Alosa fallax. An increase of 1 and 2° C above the current mean summer (June to August) water temperature of 17.8° C was estimated to result in a three and six-fold increase in the population, respectively. Climate change is also predicted to result in an earlier commencement to their spawning migration into fresh water. The model was expanded to investigate the effect of any additional mortality that might arise from a tidal power barrage across the Severn Estuary. Turbine mortality was separated into two components: (1) juvenile (pre-maturation) on their out migration during their first year and on their first return to the river to spawn and (2) post-maturation mortality on adults on the repeat spawning component of the population. Under current conditions, decreasing pre-maturation and post-maturation survival by 8% is estimated to result in the stock becoming extinct. It is estimated that an increase in mean summer water temperature of 1° C would mean that survival pre and post-maturation would need to be reduced by c. 10% before the stock becomes extinct. Therefore, climate change is likely to be beneficial to populations of A. fallax within U.K. rivers, increasing survival and thus, population persistence. © 2010 The Authors. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.