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In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e. reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had higher rates of methane emission and production. It is argued that this difference in methane emission between sites was primarily due to a different effect of reed and bulrush plants on methane dynamics rather than methane oxidation related to tidal elevation. Methane emission showed strong seasonality related primarily to plant physiology and only secondarily to temperature. Two control sites at which vegetation was removed systematically had lower emission rates indicating an overall stimulating effect of plants on methane emission from tidal marshes. Flooding reduced methane emission, probably by blocking the primary sites of methane release in the lower part of the plant stems.

A review of recent literature showed that methyl mercury concentrations contributed less than 1 per cent of total mercury in precipitation in industrial areas. Following atmospheric deposition the mercury levels in fish were affected by environmental parameters within the catchment and the aquatic system demonstrating the importance of assessing the contributions of local geology to background mercury levels in fish (estimated as 0.2-1.0 mg per kg compared to the preindustrial level of 0.15 mg per kg). The methyl mercury:total mercury ratio in fish muscle tissue was generally unity regardless of environmental contamination and the major route of methyl mercury uptake in fish was biomagnification from sediment, food and respiration following inputs from precipitation, runoff and in-lake methylation. Aquatic systems with good acid-buffering properties had low fish mercury levels due to reduced production of methyl mercury and maintenance of gill function. Catchment and atmospheric processes combined with many physicochemical variables in the aquatic environment to influence the bioaccumulation rate and absolute concentration of mercury in fish but sufficient data were now available to develop an axiom for identifying aquatic systems likely to be susceptible to bioaccumulation from atmospherically-derived mercury. There are 250 references.

The transition to an aquatic life has been achieved by only 2% of the approximately 350,000 angiosperm species. The balance between sexual and asexual reproduction in aquatic angiosperms is discussed.

The ecosystem approach to fisheries management is high on national, regional and international agendas for sustainable fisheries management. Implementing the Ecosystem Approach to Fisheries covers both theoretical and applied aspects, with a particular emphasis on practical experiences in the form of case studies from around the world, and tools for solutions. Researchers, practitioners and policy makers in fisheries, aquaculture, marine biology and ecology will find this book an invaluable overview and guide to fisheries management.

The Bergen Conference was a follow-up to the Reykjavik Conference in 2001 and was organized by the Nordic Council of Ministers and the Governments of Iceland and Norway, with technical support from the FAO. The aims of the Conference were to review concepts and share experiences from implementation, and to identify strategies and best practices that will facilitate further implementation of the ecosystem approach to fisheries (EAF). The Conference was organized with four sessions on concepts and strategies, knowledge base, approaches and tools, and experiences from case studies, followed by a fifth session on the way forward. Many terms have been used in relation to the ecosystem approach (EA), but we are converging towards a common understanding of the concept. With respect to fisheries, the EA has two dimensions: a vertical dimension of application of the EAF and a horizontal dimension of integration of fisheries with other sectors into a holistic management framework. The EA is a strategy and not a 'blueprint' action plan, and its application needs to be tailored to the specific ecological, social and cultural conditions in each geographical area. Application of the EA may start with present knowledge, but more focused ecosystem research is needed to make it more effective, and limited knowledge requires added precautions. Ecological risk assessment (ERA) may be an important tool to apply in an EAF, as may the use of marine protected areas (MPAs) in combination with other management measures. An EAF can be kept simple and implemented incrementally from existing measures in fisheries management.

Differential sensitivities of benthic and planktonic communities of UV radiation may involve differences in habitat conditions (e.g., availability of physical refuge), taxonomic composition, UV-A (320-400 nm) and DNA-damaging UV-B (280-320 nm) irradiances, and potential indirect effects via food-web processes. These hypotheses were tested using 18 enclosures (corrals) within an alpine lake. The factorial design consisted of three UV treatments (+UV, -UV-B, -UV) and two macroinvertebrate densities (ambient, 3× ). High performance liquid chromatography was used to quantify changes in periphyton and phytoplankton abundance and composition in response to UV radiation and macroinvertebrates over a period of 1 mo. Algal and invertebrate responses to UV radiation were habitat- and taxon-specific. Epilithic standing crop was significantly suppressed by UV radiation, primarily due to UV-B radiation inhibiting diatoms by 40%. In contrast, standing crop of epipelic (sediment-dwelling) organisms was significantly enhanced by UV-A radiation, which increased the abundance of cyanobacteria by 50%. UV radiation also significantly altered the taxonomic composition of both epilithon and epipelon. In comparison, picocyanobacterial phytoplankton were unaffected by UV radiation. Zoobenthos (Gammarus lacustris, Chironomidae) and zooplankton (Hesperodiaptomus arcticus, Rotifera) did not significantly alter periphyton or phytoplankton biomass or taxonomic composition. Although total zoobenthos and zooplankton biomass were unaffected by UV radiation. UV-B significantly suppressed the final density of rotifers but not that of heavily pigmented calanoid copepods. These results show that UV radiation affects shallow-water communities in cold and unproductive systems mainly through direct effects, rather than by indirect effects mediated by food-web processes. Access to physical refuges was evidently a key factor determining habitat-specific responses to UV radiation. UV radiation did not adversely affect motile epipelon and zoobenthos that could seek refuge in sediments, but it did suppress attached epilithic taxa. In habitats devoid of physical refuge, UV tolerance was associated with photoprotective pigmentation (i.e., H. arcticus), and possibly a capacity for DNA repair (i.e., epilithic filamentous cyanobacteria and planktonic picocyanobacteria). Our findings suggest that UV exposure can affect abiotic regulation of littoral food webs in extreme environments, such as alpine, polar, and anthropogenically acidified ponds and shallow lakes.

This review of the literature concerns the gut microbiota of aquatic invertebrates and highlights the questions and processes that merit attention if an understanding of the role of gut microbes in the physiology of host invertebrates and nutrient dynamics of aquatic systems is to be gained. A substantial number of studies report the presence of gut microbes in aquatic invertebrates. Crustacea, Mollusca, and Echinodermata have received the most attention, with few studies involving other invertebrate groups. Different types of associations (e.g, ingestion, contribution of exoenzymes, incubation, parasitism) are reported to occur between gut microbes and aquatic invertebrates, and it is clear that gut bacterial communities cannot be treated as single functional entities, but that individual populations require examination. In addition, gut microbes may be either ingested transients or residents, the presence of which have different implications for the invertebrate. The most commonly reported genera of gut bacteria are Vibrio, Pseudomonas, Flavobacterium, Micrococcus, and Aeromonas. Quite a number of authors report the physiological properties of gut microbes (including enzyme activities and attributes such as nitrogen fixation), while less attention has been given to consideration of the colonization sites within the digestive tract, the density and turnover of gut bacteria, and the factors affecting the presence and nature of gut microflora. In addition, although a few studies have demonstrated a positive relationship between invertebrates and their gut microbiota, particularly with regard to nutrient gain by the invertebrate, very little conclusive evidence exists as to the role of bacteria in the physiology of host invertebrates. This has resulted from a lack of process-oriented studies. The findings for aquatic gut microbes are compared to those of gut bacteria associated with terrestrial invertebrates

This chapter will discuss the preliminary outcomes of the UN FAO Expert Consultation on the Social, Economic and Institutional (SEI) Considerations of Applying the Ecosystem Approach to Fisheries Management (6-9 June 2006). This meeting was designed to provide an understanding of the roles played by these human activity-focused perspectives within the ecosystem approach to fisheries (EAF) process as presented through the meeting's background document, including: (i) as a driving force for EAF; (ii) as a means for valuation of potential costs and benefits; (iii) as instruments in the application of EAF; and (iv) as institutions supporting or constraining the EAF. In addition, the meeting provided guidance on proposed FAO Technical Guidelines focusing on the human dimension of the EAF.

There is widespread agreement on the need to enlarge our fishery management 'toolbox', thereby increasing the range of creative measures available to suit the panoply of fisheries that managers face. This chapter attempts to broaden the toolbox discussion by focusing on a certain subset of management mechanisms: the use of incentives. A brief introduction by means of a problem statement and the possible role of incentives in addressing these issues is followed by a description and discussion of incentives as categorized into legal, institutional, economic and social incentives. In addition, concise examples are provided as starting points for further investigation. The ultimate goal of this chapter is to stimulate discussion regarding the appropriateness and desirability of including the use of incentives as part of the toolbox within EAF strategies towards sustainable development.

The Reykjavik Conference on 'Sustainable Fisheries in the Marine Ecosystem' in 2001, and the commitment made by FAO members in the Reykjavik Declaration to responsible and sustainable fisheries in the marine ecosystem, strengthened and legitimized the ecosystem approach to fisheries (EAF) as the reference framework for managing the fishery sector. This direction was further reinforced by the World Summit on Sustainable Development (WSSD) (Johannesburg, 2002) that recommended the implementation of an ecosystem approach to aquatic resources management by 2010. The requirements implicit in the EAF, such as addressing more complex and poorly understood systems and the associated uncertainty, increasing data requirements, consideration of several timescales, and the recognition of the importance for a broader stake-holder participation at various stages of the fisheries management process, have initially intimidated many and fostered a perception of the EAF as a difficult and perhaps impossible task. Furthermore, the understanding of the basic principles of what an ecosystem approach actually implies are still not always understood or agreed upon. Attitudes are however changing, both at the international and at the national levels, and a pragmatic approach has been adopted in many places to see how conventional fisheries management can be improved to incorporate ecosystem considerations and more properly deal with the social dimension. While it could be argued that a large proportion of FAO's work is either directly or indirectly promoting the application of an ecosystem approach, FAO has also specifically addressed EAF by developing guidelines for its implementation, following the mandate issued in connection with the Reykjavik Conference. Promotion has been conducted in a number of conferences, regional and national initiatives have been monitored informally and specific case studies have been implemented through field projects. This contribution will summarize the developments in the conceptual framework that have taken place in FAO since the Reykjavik Conference, and try to put emphasis on the basic principles that should underpin the application of the EAF. Despite the progress made, important challenges still need to be faced. These are not only related to the direct drivers of marine ecosystem change, such as fisheries and other sectors utilizing goods and services from the marine ecosystem, but also related to the indirect drivers such as changes in human population coupled with a widespread aspiration for an improved standard of living, and global economic policies.