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Wesllawski J.M.,Polish Academy of Sciences | Opanowski A.,University Of Szczecin | Legezynska J.,Polish Academy of Sciences | Maciejewska B.,Ecological Consultancy Services Ltd EcoServe | And 2 more authors.
Polish Polar Research | Year: 2010

The life modes and sizes of 98 species of higher crustaceans (Malacostraca) from Hornsund and Kongsfjorden (Svalbard fjords) were analyzed. The majority (90%) of the species were perennial, K strategists, with eight- to tenfold size differences between newborn and adult specimens. The largest species are carnivores and carrion feeders, while the smallest are sediment-dwelling suspension and deposit feeders. Compared with the crustacean fauna of northern Norway (over 500 species), the Svalbard fjord crustacean fauna is less diverse (below 150 species). The crustacean species populations from the Arctic fjord are more numerous (average number of ind./species/m2) compared to those of the northern Norway boreal fjords. Crustaceans with long life cycles and distinct size difference between juveniles and adults represent three to five ecologically different functional "species" each, since the smaller size groups of the same species differ with regard to theirmobility, food and habitat use. Thus, crustaceans are ecologically and functionally more diverse than expected from simple species count. Source

Penk M.R.,Ecological Consultancy Services Ltd EcoServe
Biology and Environment | Year: 2011

Mysis salemaai forms an important part of the food web, linking the trophic networks of the pelagic and benthic zones. This study examined the current distribution of M. salemaai in Ireland and the species was recorded from eight lakes. This included some previously known one-off records overlooked in distribution reviews and a new record from Lough Derravaragh. Together with its well-documented occurrence in Northern Ireland, this makes ten lakes where the species is known on the island of Ireland. On account of its deep-water habit, M. salemaai has been under-recorded in Ireland, and its distribution may extend to other Irish lakes. There were significant differences in body size in the studied lakes and adults ranged from 11.5 ±0.01mm in Lough Allen to 15.6 ±0.01mm in Lough Corrib. The abundance varied significantly and ranged from 0.3 ±0.1m 3 and 0.5 ± 0.3m 3 in Lough Ree and Lough Derg (respectively) through 1.8 ±0.5m 3 in Lough Allen to 12.8 ±4.7m 3 in Lough Corrib. Despite its relatively wide distribution in Ireland, the abundance in most lakes appears low and its status may be under threat from eutrophication, climate change and the introduction of alien species. © Royal Irish Academy. Source

Knight L.R.F.D.,Hypogean Crustacea Recording Scheme | Penk M.R.,Ecological Consultancy Services Ltd EcoServe
Biology and Environment | Year: 2010

Survey work on the stygobitic Crustacea (Malacostraca) species of Ireland was carried out in spring 2008, with funding from the Heritage Council's Wildlife Grant Scheme (Grant no. 16426). The survey, which concentrated on springs and caves, produced 26 records from 23 new locations. Most of the records were of Niphargus kochianus irlandicus, the commonest and most widespread of the four currently known Irish species. The Carrowmore cave system in County Sligo is currently the northernmost record for N. kochianus irlandicus in Ireland and for the genus Niphargus in Europe. Niphargus wexfordensis, previously only known from County Wexford was discovered at four new locations, including counties Cork, Kilkenny and Clare. The sole record of the tiny Microniphargus leruthi was from riverine interstitial gravels on the Dripsey River, Co. Cork. This is the third record of this species from Ireland, following its discovery in 2006. Sixty-five sites were sampled in total, and taxa lists include epigean (surface-dwelling) taxa found within the groundwater habitats. © Royal Irish Academy. Source

Atalah J.,University College Dublin | Atalah J.,Ecological Consultancy Services Ltd EcoServe | Crowe T.P.,University College Dublin
Journal of Experimental Marine Biology and Ecology | Year: 2010

Coastal areas around the world are experiencing increasing disturbance from multiple stressors caused by anthropogenic activities. Although there is good knowledge about the impacts of individual stressors, there is less understanding of the consequences of several stressors acting simultaneously. Eutrophication and sediment deposition are widely recognized as major problems for the functioning of coastal systems, and they are expected to increase during the next decades. In a field experiment, using rock pools as a model system, different levels of nutrients and sedimentation were applied in a factorial experimental design that also accounted for the influence of molluscan grazers. Sedimentation significantly changed assemblage structure, mainly owing to an increase in turfing and filamentous algae and a decrease in crustose algae. Nutrients also caused an increase in the cover of green filamentous algae, which in turn was synergistically magnified by the removal of grazers. Here we showed that these stressors can individually alter the structure of rock pools assemblages; and that in this system top-down control (by grazers) is more important than bottom-up factors (nutrients) in controlling macroalgal assemblage structure. The combined effect of grazers loss and nutrients was larger than the sum of their individual effects. This study enhanced mechanistic understanding of the impacts of multiple stressors on coastal ecosystems, which will help to develop management strategies and conservation of the marine environment. © 2010 Elsevier B.V. All rights reserved. Source

Atalah J.,University College Dublin | Atalah J.,Ecological Consultancy Services Ltd EcoServe | Kelly-Quinn M.,University College Dublin | Irvine K.,Trinity College Dublin | Crowe T.P.,University College Dublin
Hydrobiologia | Year: 2010

Aquatic ecosystems are experiencing increasing disturbance from multiple stressors caused by anthropogenic activities. The potential for multiple stressors to modify each others' impacts is not well understood. Legislation such as the EU Water Framework Directive (WFD) requires the development of tools to assess human impacts in aquatic systems that incorporate ecological elements, such as macroinvertebrates. Nutrient enrichment and invasive species are major threats to freshwater systems. The invasive zebra mussel Dreissena polymorpha is a conspicuous invader in freshwater aquatic systems in Europe and North America, and has been linked to drastic changes in macroinvertebrate communities and lake ecology. In 31 lake sites varying in nutrient pressure and in the presence or absence of D. polymorpha we tested three ecological quality assessment tools based on macroinvertebrate assemblages (% Sensitive Taxa to Total Phosphorus (TP), TP Score and Indicator Taxa Metric) and two basic ecological metrics. There were highly significant changes in macroinvertebrate diversity, structure, and composition associated with the invasion by D. polymorpha. While the three metrics performed consistently well in non-invaded systems, they lost explanatory power for eutrophication pressure in invaded systems. Our results suggest that metrics may need to be developed separately for invaded and non-invaded systems, and that the interaction between alien species and nutrient enrichment requires further investigation. © 2010 Springer Science+Business Media B.V. Source

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