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Nitrification, the oxidation of NH(4)(+) to NO(2)(-) and subsequently to NO(3)(-), plays a central role in the nitrogen cycle and is often a critical first step in nitrogen removal from estuarine and coastal environments. The first and rate-limiting step in nitrification is catalyzed by the enzyme ammonia monooxygenase (AmoA). We evaluate the relationships(More)
Ecosystem respiration is the biotic conversion of organic carbon to carbon dioxide by all of the organisms in an ecosystem, including both consumers and primary producers. Respiration exhibits an exponential temperature dependence at the subcellular and individual levels, but at the ecosystem level respiration can be modified by many variables including(More)
The growth characteristics and reproductive capacity are described for Heracleum mantegazzianum, an invasive perennial plant that has significantly increased its geographical range in Ireland in recent years. The effect of cutting on growth and seed production is described. Based on research findings, a detailed Giant Hogweed control programme is presented(More)
Concentrations of Cu and Pb were determined in the roots and shoots of six salt marsh plant species, and in sediment taken from between the roots of the plants, sampled from the lower salt marsh zone at four sites along the Suir Estuary in autumn 1997. Cu was mainly accumulated in the roots of monocotyledonous and dicotyledonous species. Pb was mainly(More)
The non-native invasive plant, Lagarosiphon major (Hydrocharitaceae) is a submersed aquatic macrophyte that poses a significant threat to water bodies in Europe. Dense infestations prove difficult to manage using traditional methods. In order to initiate a biocontrol programme, a survey for natural enemies of Lagarosiphon was conducted in South Africa.(More)
Primary production, respiration, and net ecosystem metabolism (NEM) are useful indicators of ecosystem level trophic conditions within estuaries. In this study, dissolved oxygen data collected every half hour between January 1996 to December 1998 by the National Estuarine Research Reserve System Wide Monitoring Program were used to calculate primary(More)
Attendance at the 9th International Symposium on Aquatic Weeds, held in Dublin in 1994, by 270 delegates from 35 different countries demonstrated the continuing interest in the management and ecology of freshwater plants. The relative importance of the various topics covered in this meeting is compared with that of the previous symposia (1967–1990) for(More)
Macroinvertebrates in aquatic habitats form an integral part of the diet of many freshwater fish. It is therefore important to understand the effects that weed control practices have on this community in canal fishery watercourses. The principal forms of weed control operated in the Grand and Royal Canals include mechanical cutting, using a variety of(More)
Radio telemetry was used to monitor the movement of four species of coarse fish in a 11.2 km long section of canal from January to June 1996. One specimen of bream, rudd × bream hybrid, tench and pike were captured using electrofishing apparatus and Lotek CFRT-3EMXT pulse coded aquatic transmitter tags, operating at 173.3 Mhz (with individual ID codes),(More)