State and management of wetlands in Bangladesh

Wetlands are a vital link between land and water in Bangladesh. A majority of the people of Bangladesh are critically dependent on wetlands. In this paper, the values of wetlands, causes and effects of wetlands degradation, as well as the present wetlands management approach, are analyzed and recommendations for wetlands management are suggested based on participatory rural appraisal (PRA), field visit, personal experience, and existing literature and information. Wetlands play a crucial role in maintaining the ecological balance of ecosystems, but wetlands habitat of Bangladesh is under constant threat due to increase of population, intensive agriculture, overfishing, siltation, pollution, ill-planned infrastructures, lack of institutional coordination, lack of awareness, etc. As a result biodiversity is reducing, many species of flora and fauna are threatened, wetlands-based ecosystem is degenerating, and the living conditions of local people are deteriorating as livelihoods, socioeconomic institutions, and cultural values are affected. Wetlands management is not addressed separately in water management activities of Bangladesh. In order to balance human needs and wetlands conservation, a mainly community-based wetlands management approach has been taken in Bangladesh, but this is not enough to prevent the degradation of wetlands. Therefore, Bangladesh now needs a comprehensive strategy combining political, economic, social, and technological approaches to stop further degradation of wetlands. Therefore, wetlands management should be incorporated into a system of integrated land and water use and, indeed, into the socioeconomic system of the country. Policies, strategies, and management plans for sustainable use and conservation of wetlands of Bangladesh must be based on solid knowledge and understanding of their ecological and socioeconomic functions and processes.     

Ecohydrology as a new tool for sustainable management of estuaries and coastal waters

Throughout the world, estuaries and coastal waters have experienced degradation. Present proposed remedial measures based on engineering and technological fix are not likely to restore the ecological processes of a healthy, robust estuary and, as such, will not reinstate the full beneficial functions of the estuary ecosystem. The successful management of estuaries and coastal waters requires an ecohydrologybased, basin-wide approach. This necessitates changing present practices by official institutions based on municipalities or counties as an administrative unit, or the narrowly focused approaches of managers of specific activities (e.g., farming and fisheries, water resources, urban and economic developments, wetlands management and nature conservationists). Without this change in thinking and management concept, estuaries and coastal waters will continue to degrade, whatever integrated coastal management plans are implemented. To help in this process of change there is a need to (1) develop a profound understanding of the effects of biota and biotic processes on mediating estuary response to changing hydrology, sediment and nutrient flux and of the biota on hydrology at the river basin scale, and (2) to develop science-based remediation measures at the river basin scale, with elements of ecohydrology and phytotechnology at their core, to strengthen the ability of the biota to sustain and adapt to human-induced stresses.This revised version wa published online in March 2005 with corrections to the issue cover date.     

Nutrient leaching in dry heathland ecosystems: effects of atmospheric deposition and management

Atmospheric nutrient deposition has contributed to widespread changes in sensitive seminatural ecosystems throughout Europe. For an understanding of underlying processes it is important to quantify input–output flows in relation to ongoing atmospheric inputs and current management strategies. In this study we quantified losses of N, P, Ca, Mg, and K via leaching in heathland ecosystems (Lüneburger Heide, NW Germany) as a function of current deposition rates and different management measures (mowing, prescribed burning, choppering, sod-cutting) which aim to prevent shrub and tree encroachment. Leaching was only moderately related to atmospheric input rates, indicating that leaching was mostly affected by internal turnover processes. Leaching significantly increased for most of the nutrients after the application of management measures, particularly in the choppered and sod-cut plots. However, atmospheric nutrient inputs exceeded leaching outputs for most of the nutrients, even in the plots subjected to management. Despite high deposition rates (20–25 kg N ha⁻¹ year⁻¹), retention of atmospheric N input ranged between 74% and 92% in the control plots. In the treated plots, N retention decreased to 59–80%. However, in the study area mean N leaching in the controls has almost doubled since 1980 and currently amounts to 3.7 kg ha⁻¹ year⁻¹, indicating an early stage of N saturation. Our study provides evidence that leaching did not compensate for atmospheric nutrient deposition, particularly as regards N. Management, thus, will be an indispensable tool for the maintenance of the low-nutrient status as a prerequisite for the long-term preservation of heathland ecosystems.     

Fossil insects and ecosystem dynamics in wetlands: implications for biodiversity and conservation

We review the uses of fossil insects, particularly Coleoptera (beetles) and Chironomidae (non-biting midges) from ancient deposits to inform the study of wetland ecosystems and their ecological and restoration processes. In particular, we focus on two contrasting ecosystems, drawing upon research undertaken by us on British raised mire peats and shallow lake systems, one an essentially terrestrial ecosystem, the other aquatic, but in which wetland insects play an important and integral part. The study of raised mire peats suggests that faunal stability is a characteristic of these wetland systems, over what appear to be extensive periods of time (up to several millennia), whilst studies of shallow lake ecosystems over recent timescales indicates that faunal instability appears to be more common, usually driven by increasing eutrophication. Drawing upon a series of fossil Coleoptera records spanning several thousand years from Hatfield Moors, south Yorkshire, we reconstruct in some detail the mire’s ontogeny and fluctuations in site hydrology and vegetation cover, illustrating the intimate association between substrate, topography and peat development. A comparison between fossil and modern beetle populations indicates that the faunal characteristics of this mire and its adjacent neighbour, Thorne Moors, become established during the early phases of peat development, including its rare endemics, and that the faunal biodiversity on the sites today is dictated by complex site histories. The over-riding characteristic of these faunas is of stability over several thousand years, which has important implications for the restoration of degraded sites, especially those where refugial areas are limited. In contrast, analyses of fossil Chironomidae from shallow lakes allow researchers to track changes in limnological status and while attempts have been made to reconstruct changes in nutrient levels quantitatively, the chironomids respond indirectly to such changes, typically mediated through complex ecosystem dynamics such as changes in fish and/or macrophyte communities. These changes are illustrated via historic chironomid stratigraphies and diversity indices from a range of shallow lakes located across Britain: Slapton Ley, Frensham Great Pond, Fleet Pond, Kyre Pool and Barnes Loch. These sites have shown varying degrees of eutrophication over recent timescales which tends to be associated with a decline in chironomid diversity. While complex functional processes exist within these ecosystems, our evidence suggests that one of the key drivers in the loss of shallow lake chironomid diversity appears to be the loss of aquatic macrophytes. Overall, while chironomids do show a clear response to altered nutrient regimes, multi-proxy reconstructions are recommended for a clear interpretation of past change. We conclude that if we are to have a better understanding of biota at the ecosystem level we need to know more of the complex interactions between different insect groups as well as with other animal and plant communities. A palaeoecological approach is thus crucial in order to assess the role of insect groups in ecosystem processes, both in the recent past and over long time scales, and is essential for wetland managers and conservation organisations involved in long term management and restoration of wetland systems     

The role of constructed wetlands in secondary effluent treatment and water reuse in subtropical and arid Australia

Water reclamation and reuse is being actively promoted in Australia. In Queensland, surface-flow constructed wetlands with a diversity of macrophyte types offer the greatest potential for effluent polishing. Constructed wetlands in subtropical climates in coastal regions and arid climates in inland western regions are conducive to high macrophyte growth rates and nutrient removal, in particular nitrogen, producing an effluent suitable for irrigation, restoration of wetlands and/or release into natural waterways. Faecal-coliform removal is also high, producing effluent with <1000 cfu/100 mL and as low as 100 cfu/100 mL, acceptable for agricultural irrigation. Constructed wetlands can be designed to maximise the removal of both nutrients and pathogens by enhancing macrophyte diversity and natural disinfection processes by incorporating lagoons, shallow-water wetlands and subsurface-flow wetlands into the treatment train. Surface-flow wetlands can also be designed to minimise mosquito breeding by increasing macro-invertebrate predators, thereby alleviating community concerns about potential health risks. This paper addresses the role of constructed wetlands in nutrient and pathogen removal in Queensland's wetlands, and presents three case studies with respect to effluent reuse.     

Conserving the Himalayan forests: approaches and implications of different conservation regimes

The conservation of Himalayan forests is big concern in view of global agenda. Many studies in this endeavor reported that the rate of forests degradation is posing a severe threat to the landscape and existing biodiversity in the Himalayas. Currently there many conservation approaches exists and of them four are widely recognized (1) Conservation through traditional religious beliefs “traditional conserved forests” (TCF); (2) Conservation through governmental planning and schemes “government conserved forests” (GCF); (3) Conservation through creation of protected areas (PAF); and (4) Conservation through community efforts “community conserved forests” (CCF). Our hypothesis in this direction says that all the conservation approaches lead to same results concerning to forest conservation. To testify our hypothesis we have studied the forests of each conservation regimes and evaluated them based on the identified indicators. We have done empirical studies and following the cloud-free satellite data were used for last three decades (such as Multi-Spectral Scanner, Linear Imaging and Self Scanning, and Enhanced Thematic Mapper ) to study a change in vegetation dynamics of the mountain forests in multi-temporal dimension. Our research concluded that community conservation approach have greater significance for biodiversity conservation and management in the Himalayan region. Here we support the model of CCF for forest ecosystem conservation, alongside the sustainable livelihood of the mountain societies. But every conservation regimes has its own importance in viewpoint of the particular objectives. Therefore, we suggests advancement and revision of PAF and GCF however, some elements of CCF can be introduced in TCF for making up it more sound in view of rapid socio-economic and cultural changes taking place in the communities. An erratum to this article can be found at     

Environmental conditions and phosphorus removal in Florida lakes and wetlands inhabited by Hydrilla verticillata (Royle): implications for invasive species management

Hydrilla verticillata is considered the most problematic aquatic plant in the United States. In south Florida, Hydrilla dominance has also been documented in treatment wetlands. This paper characterizes (1) environmental conditions which favor Hydrilla growth and (2) understand its nutrient removal capability. Despite its occurrence over a wide range of environmental conditions, Hydrilla abundance increased with increasing pH, alkalinity, total P and total N, and decreased with water depth in selected Florida lakes. No relationship was found between color, Secchi depth and Hydrilla abundance. In several Hydrilla-dominated lakes, mean total P concentration (126 μg/l) at inflow was reduced to 106 μg/l at outflow. The maximum inflow total P concentration in a lake with positive nutrient reduction was 148 μg/l. Total P removal efficiency by Hydrilla-dominated lakes and wetlands was comparable to or higher than systems dominated by emergent and other submerged plants. Mean total P settling rates for lakes and a constructed wetland dominated by Hydrilla were estimated at 19 and 34 m/year, respectively, which were higher than or comparable to similar systems dominated by other aquatic plants. Results from this study suggest that reduction of Hydrilla from constructed wetlands will not likely improve nutrient removal performance.     

Forest succession in Kibale National Park, Uganda: implications for forest restoration and management

Forest succession was studied in four plots in former grasslands at the Ngogo study area in Kibale National Park, Uganda. The plots were located in areas that had been protected from fire for 0.58, 25, 9 and ≈30 years for plots 1, 2, 3 and 4, respectively. Species richness reflected the length of time that the plot had been protected from fire; it was highest in plot 4 and lowest in plot 1. Species density, stem density and basal area were all highest in plot 4 and lowest in plot 1. The species densities of plots 2 and 3 were not different. Similarly, plots 2 and 4 did not differ with regard to stem density or basal area. Animal seed dispersers played a vital role in the colonization of grasslands by forest tree species.     

Grouse moor management: habitat and conservation implications for invertebrates in southern Scotland

The distribution of ground beetle, rove beetle, spider and plant bug species assemblages, and the occurrence of other beetle species, was investigated in a five-year survey of a grouse moor in the Scottish borders, some of which was managed by burning, cutting and herbicide application. Multivariate analyses were used to assess the relationship between assemblage distribution and a number of environmental variables. The management of dry Calluna moor had a positive effect on the habitat diversity for ground beetles and plant bugs but had little effect on rove beetles and spiders. A total of 39 nationally rare and scarce species (38 beetle, 1 plant bug) was recorded in the survey. The most important habitat present was on streamside sites, especially sediment. A number of these rarer species were restricted to sites managed by burning and cutting but other species were only found on unmanaged wet Calluna moor. Molinia-dominated moor was generally of poorer quality than Calluna sites, with fewer rare and scarce species and lower site rarity values based on the ground beetle species recorded. The highest median site rarity scores were for dry, open, managed Calluna sites. In order to maximise both habitat diversity and the incidence of rare and scarce species on grouse moor, a mosaic of both managed and undisturbed patches differing in soil characteristics, plant composition and vegetation structure appears to be required.     

Effects of dissolved oxygen on extracellular enzymes activities and transformation of carbon sources from plant biomass: implications for denitrification in constructed wetlands

Dissolved oxygen (DO) concentrations have often been shown to be important to decomposition rates of plant litter and thus may be a key factor in determining the supply of dissolved organic carbon (DOC) and carbon-dependent denitrification in wetlands. During the 2 months operation, DOC accumulation in anaerobic condition was superior to aerobic condition due to higher activities of hydrolase enzymes and lower hydrolysates converted to gaseous C. Also, much higher denitrification rates were observed in wetland when using anaerobic litter leachate as the carbon source, and the available carbon source (ACS) could be used as a good predictor of denitrification rate in wetland. According to the results of this study, extracellular enzymes activities (EEAs) in wetland would change as a short-term consequence of DO. This may alter balance of litter carbon flux and the characteristics of DOC, which may, in turn, have multiple effects on denitrification in wetlands.     

Elasmobranchs in southern Indonesian fisheries: the fisheries, the status of the stocks and management options

The biology of elasmobranchs makes them very vulnerable to fishing pressure and there is increasing international concern over their exploitation. In northern Australia the stocks of some species may be shared with those in southern Indonesia. Indonesia has the highest landings of elasmobranchs worldwide (>100,000 t p.a.) and millions of Indonesian artisanal fishers rely heavily on elasmobranchs taken in target fisheries. They are also taken by industrial trawlers and as bycatch in pelagic tuna fisheries. This paper, resulting from a collaborative project between Australia and Indonesia, summarises the elasmobranch fisheries; the characteristics of the fisheries are outlined, the status of the stocks are assessed, and management options described and discussed. The project focussed on representative markets and fish landing sites in southern Indonesia from 2001 to 2005. Data were from market surveys, the records of the Indonesian Directorate General of Capture Fisheries, and from research cruises. Data from the ongoing tuna monitoring programme showed that shark bycatch from the tuna fleets forms about 11% of shark landings in Indonesia. Yield per recruit and related analyses were used to integrate biological information to indicate the productivity of each species to allow for management policy options and constraints. Research cruise data show that catch rates of elasmobranchs in the Java Sea declined by at least one order of magnitude between 1976 and 1997. The results indicate strongly that many of the shark and ray species in Indonesia are overfished and that the most effective management strategy may need to involve capacity control, such as licencing, gear restrictions and catch limits, together with controls on the fin trade.     

Endangered stands of thuriferous juniper in the western Mediterranean basin: ecological status, conservation and management

Thuriferous juniper is only found in isolated parts of the western Mediterranean: France (Alps, Pyrenees and Corsican highlands), Spain, Algeria and Morocco. These semi-arid mountain stands, where thuriferous juniper trees grow in low-density open woodland, are seriously endangered: (i) In the Atlas mountains, the thuriferous juniper stands are heavily degraded as a result of the intensive wood removal and livestock activity in these densely populated areas. This situation, which will soon become irreversible unless remedial measures are urgently taken, has produced impoverished soils and hillside instability while contributing to desertification. (ii) In Spain, although livestock activity and cultivation have strongly reduced areas occupied by Juniperus thurifera, stands are still numerous and, in some regions, show a good regeneration due to conservation measures. (iii) In France, the decline in human and livestock activities over recent decades has led to a recolonization of some of the Juniper stands by pines or oak. A forest management system that enables these original stands to survive and regenerate must be undertaken without delay. The dynamics of evolution of these stands is quite different north and south of the Mediterranean. In both cases, conservation measures are urgently required to protect or rehabilitate these original stands with floristic, ecological and socio-economic interest.     

Conservation genetics of the franciscana dolphin in Northern Argentina: population structure,by-catch impacts,and management implications

Evaluating population structure in the marine environment is a challenging task when the species of interest is continuously distributed, and yet the use of population or stock structure is a crucial component of management and conservation strategies. The franciscana dolphin (Pontoporia blainvillei), a rare endangered coastal cetacean, suffers high levels of by-catch all along its distribution range in the Western South Atlantic, and questions have been raised about boundaries or divisions for population management. Here we apply genetic tools to better understand population structure and migration, sex-biased dispersal, and to assess potential genetic and demographic impacts of by-catch. Our analyses, based on mtDNA control region sequences, reveal significant genetic division at the regional level and fine-scale structure within our study area. These results suggest that the population in northern Buenos Aires is the most isolated population in Argentina. We found no significant departure from an equal sex ratio among the by-caught animals. A few cases of multiple entanglements appeared to be mother–calf pairs based on field observations and individuals sharing the same mtDNA control region lineage. The distribution of haplotype frequencies observed could imply that some maternal lineages are more prone to be subject to higher rates of by-catch, although biopsy sampling is necessary to fully evaluate whether maternal lineage distributions are the same for biopsy sampled and by-caught animals. A genetic indication of population size disequilibrium was detected for all populations in Argentina, which is consistent with available rates of by-catch and abundance estimates. Collectively, our findings support the current scheme of larger recognized Franciscana Management Areas (FMA), but argue for a finer-scale subdivision within Northern Buenos Aires region (FMA IV). Finally, an integrated approach to promote conservation of this endangered small cetacean has to involve identification of genetic and demographic threats, a more sustainable fishery strategy to reduce by-catch, and designation of protected areas that are supported by underlying population structure for franciscana dolphins.     

Disturbances to great bustards (<Emphasis Type="Italic">Otis tarda</Emphasis>) in central Spain: human activities,bird responses and management implications

We investigated the effects of human activities on the behaviour of great bustards (Otis tarda) in a Special Protection Area in central Spain. We recorded 532 disturbances, at a rate of 0.93 disturbances per hour, a high value compared to other studies. Escape (flight/running) was observed more often than alert. Flight was more frequent than running. Car traffic and walkers were the main sources of disturbance. Motorcyclists, dogs, helicopters and aeroplanes were also harmful in relation to their abundance and time of permanence. Farming and shepherding produced few disturbances and usually did not cause a flight response. These activities are thus considered compatible with the conservation of the great bustards. Hunting caused an increase in the frequency of disturbance on weekends and holidays with respect to working days. We propose access restrictions to car traffic and helicopters/airplanes and hunting limitations in those areas more frequently used by the species. Pablo Sastre and Carlos Ponce Cabas contributed equally to this work.     

Growth and survival of the invasive alga, <Emphasis Type="Italic">Caulerpa taxifolia</Emphasis>, in different salinities and temperatures: implications for coastal lake management

The alga Caulerpa taxifolia is an invasive pest species in many parts of the world and has recently become established in several estuaries in south eastern Australia. A major infestation has occurred in Lake Conjola, an intermittently open and closed coastal lagoon in southern NSW. Short term (1 week) laboratory experiments were carried out to investigate growth and survival of fragments of C. taxifolia collected from this outbreak, under a range of salinities (15–30 ppt) and water temperatures (15–30°C). Fronds, stolons and thalli of the alga all displayed similar responses. Many of the algal fragments doubled in size over the week and a maximum growth rate of 174 mm/week was recorded. Fragments showed good growth (> 20 mm/week) at salinities > 20 ppt and temperatures > 20°C. Almost total mortality occurred at salinities lower than 20 ppt and temperatures less than 20°C. Historical records of water quality demonstrate that prior to entrance manipulation in 2001, salinities in Lake Conjola had often dropped to below 17 ppt for extended periods (up to 2 years). This suggests that management of the alga may be improved if the lake was allowed to undergo its normal cycles of opening and closing to the ocean, and that entrance manipulation may be one factor that has influenced the success of this invasive species.