EMPHASIS ON DISTRIBUTION: STRATEGIES FOR SMALL SCALE WATER RESOURCES DEVELOPMENT IN THAILAND1

This paper discusses strategies for the development of water resources, emphasizing the delivery of reliable water supplies, for both domestic and production purposes, to every village and to every farmer. This necessitates a shift of emphasis from the construction of large storage reservoirs to the construction, operation, and maintenance of water distribution systems capable of reaching the largest number of farms, and a shift from projects that benefit the few, to projects that benefit the many. Water distribution in this context takes on three interrelated meanings: a geographical meaning, a technical meaning, and an economic meaning. The geographical meaning focuses on the spatial distribution of the recipient population as a key to identifying the proper distribution of water projects in physical space. The technical meaning relates to the physical distribution of water through canal systems to the farmers' fields. The economic meaning refers to the equitable distribution of benefits from water projects. The paper provides an illustration of the need for an emphasis on distribution, using the state of development of water resources in northeast Thailand as an example, with a proposed program for the further development of these resources. The northeast, the poorest region in the country, has been recognized by the Government of Thailand as a priority area for accelerated regional development efforts.     

The deep-ocean option for the disposal of sewage sludge

Summary Present methods of disposal of high-bulk low-toxicity wastes, such as sewage sludge, into shallow marine environments are beginning to be questioned by many environmentalists. The alternative options generally considered all have environmental costs. A novel approach of discharging such wastes as slurries into the deep ocean at depths of 4,000 m close to the abyssal sea bed is considered. Such disposal would fulfil all the criteria required by the Oslo Convention before dumping at sea can be permitted, in that it isolates the waste from Man's ambit and offers no threat to present or foreseeable uses of the ocean. It also seems to fulfil the criteria of the World Conservation Strategy, so long as the oxygen levels in the deep waters of the ocean are not reduced excessively. The improvements in the quality of coastal seas would offset the doubling in the economic cost of disposal.Dr Martin V. Angel is the Head of the Biological Oceanography Group at the Institute of Oceanographic Sciences Deacon Laboratory. He serves on the Council of the WWF, UK and is a member of its Conservation Review Group. He is also a member of the IUCN Commission of Ecology, with particular interests in conservation of oceans and Antarctica. His professional expertise is in the ecology of deep-living pelagic organisms in the oceans but he is also an editor of a research journal,Progress in Oceanography and an external examiner for the Open University.     

δ<Superscript>15</Superscript>N as a natural tracer of particulate nitrogen effluents released from marine aquaculture

The flow of particulate nitrogen from marine net pen fish farm effluents to the surrounding biofouling community was quantified by means of stable isotopes of nitrogen. Plastic mesh substrates were deployed at 8 m depth near a sea bream fish farm and at a nearby reference site in the northern Gulf of Aqaba (Red Sea) to assess whether natural fouling organisms could sequester substantial quantities of farm-derived particulate nitrogen waste. A mixing equation, incorporating differences in nitrogen stable isotope composition, δ¹⁵N, between particulate organic matter (“source”) and fouling organisms (“sink”) at the fish farm and reference site, was used to estimate the amount of farm-derived nitrogen that was incorporated by the fouling community. Among the conspicuous fouling organisms examined, sponges, tunicates and polychaetes showed greatest uptake of fish farm N, where the mean fractions of farm-derived N estimated over the 2-year period of observation were 19±7, 22±6 and 31±8% of total organisms’ N content, respectively, with maximal recorded seasonal values of 68, 85 and 57%, respectively. Mean N uptake by mixed fouling communities (conspicuous + cryptic organisms) was as much as fivefold higher than that calculated for the sum of conspicuous taxa, suggesting that the retention efficiency is greater in mixed than in mono-specific biofouling communities.     

Sex attractant of an arctiid moth (Utetheisa ornatrix): A pulsed chemical signal

Summary The sex attractant pheromone produced by the female of the moth Utetheisa ornatrix was shown to contain Z, Z, Z-3, 6, 9-heneicosatriene. The compound, whose structure was confirmed by synthesis, proved active in electroantennogram and field bioassays. Pheromone emission occurs discontinuously, in the form of short pulses (pulse repetition rate=1.5±0.2 pulses/s). It is argued that such temporal patterning — which had not previously been demonstrated for an airborne chemical signal — can provide close-range orientation cues to the male moth as it seeks out the female.     

Seasonality of contamination, toxicity, and quality values in sediments from littoral ecosystems in the Gulf of Cádiz (SW Spain)

To seasonally evaluate littoral contamination, toxicity and quality values of sediments from the Gulf of Cádiz, we measured chemical concentrations and conducted toxicity tests in winter and summer and linked these results by means of multivariate analysis. Sediment samples were subjected to two separate, replicated sediment toxicity tests (Microdeutopus gryllotalpa amphipod survival, and Ruditapes philippinarum clam reburial), and to comprehensive sediment chemistry analyses (grain size, organic carbon, 14 heavy metals, and the surfactant linear alkylbenzenesulfonate (LAS)). Only sediments associated with an untreated urban discharge were toxic and related to high levels of surfactant LAS, Ag, and Pb. Multivariate analysis indicated that variables and chemicals associated with geochemical matrix and background levels (specific surface, Fe, Zn, Cu, V, Ni, and Co), chemicals associated with untreated urban discharge sources, and toxicity effects showed no seasonal variability. Only copper concentrations showed seasonal differences, being toxic during the winter and not toxic during summer. Multivariate analysis permits us to derive sediment quality values (SQVs); in terms of concentrations at or below which biological effects were not measured (mg kg(-1) dry sediment), are: LAS, 2.6; lead, 66.8; silver, 0.78; copper, 69.6.     

The Sulu-Sulawesi Sea: environmental and socioeconomic status, future prognosis and ameliorative policy options

The Sulu-Sulawesi Sea, with neighboring Indonesian Seas and South China Sea, lies at the center of the world's tropical marine biodiversity. Encircled by 3 populous, developing nations, the Philippines, Indonesia and Malaysia, the Sea and its adjacent coastal and terrestrial ecosystems, supports ca. 33 million people, most with subsistence livelihoods heavily reliant on its renewable natural resources. These resources are being impacted severely by rapid population growth (> 2% yr-1, with expected doubling by 2035) and widespread poverty, coupled with increasing international market demand and rapid technological changes, compounded by inefficiencies in governance and a lack of awareness and/or acceptance of some laws among local populations, particularly in parts of the Philippines and Indonesia. These key root causes all contribute to illegal practices and corruption, and are resulting in severe resource depletion and degradation of water catchments, river, lacustrine, estuarine, coastal, and marine ecosystems. The Sulu-Sulawesi Sea forms a major geopolitical focus, with porous borders, transmigration, separatist movements, piracy, and illegal fishing all contributing to environmental degradation, human suffering and political instability, and inhibiting strong trilateral support for interventions. This review analyzes these multifarious environmental and socioeconomic impacts and their root causes, provides a future prognosis of status by 2020, and recommends policy options aimed at amelioration through sustainable management and development.     

Marine snow studies in the Northeast Atlantic Ocean: distribution,composition and role as a food source for migrating plankton

During a 25 d Lagrangian study in May and June 1990 in the Northeast Atlantic Ocean, marine snow aggregates were collected using a novel water bottle, and the composition was determined microscopically. The aggregates contained a characteristic signature of a matrix of bacteria, cyanobacteria and autotrophic picoplankton with inter alia inclusions of the tintiniid Dictyocysta elegans and large pennate diatoms. The concentration of bacteria and cyanobacteria was much greater on the aggregates than when free-living by factors of 100 to 6000 and 3000 to 2 500 000, respectively, depending on depth. Various species of crustacean plankton and micronekton were collected, and the faecal pellets produced after capture were examined. These often contained the marine snow signature, indicating that these organisms had been consuming marine snow. In some cases, marine snow material appeared to dominate the diet. This implies a food-chain short cut wherby material, normally too small to be consumed by the mesozooplankton, and considered to constitute the diet of the microplankton can become part of the diet of organisms higher in the food-chain. The micronekton was dominated by the amphipod Themisto compressa, whose pellets also contained the marine snow signature. Shipboard incubation experiments with this species indicated that (1) it does consume marine snow, and (2) its gut-passage time is sufficiently long for material it has eaten in the upper water to be defecated at its day-time depth of several hundred meters. Plankton and micronekton were collected with nets to examine their vertical distribution and diel migration and to put into context the significance of the flux of material in the guts of migrants. Gut flux for the T. compressa population was calculated to be up to 2% of the flux measured simultaneously by drifting sediment traps and <5% when all migrants are considered. The in situ abundance and distribution of marine snow aggregates (>0.6 mm) was examined photographically. A sharp concentration peak was usually encountered in the depth range 40 to 80 m which was not associated with peaks of in situ fluorescence or attenuation but was just below or at the base of the upper mixed layer. The feeding behaviour of zooplankton and nekton may influence these concentration gradients to a considerable extent, and hence affect the flux due to passive settling of marine snow aggregates.     

Acid mine drainage pollution in the Tinto and Odiel rivers (Iberian Pyrite Belt, SW Spain) and bioavailability of the transported metals to the Huelva Estuary

The Tinto and Odiel rivers are seriously affected by acid mine drainage (AMD) from the long-term mining activities in Iberian Pyrite Belt (IPB). As a consequence, the Huelva estuary is heavily contaminated by metals and metalloids. This study presents an estimation of the seasonal variation, and the dissolved contaminant load transported by both rivers from February 2002 to September 2004. Besides, toxicity and bioaccumulation tests with the sediments of the estuary have been conducted in order to measure the mobility of the toxic metals. Results show that the Tinto and Odiel rivers transport enormous quantities of dissolved metals to the estuary: 7900 t yr(-1) of Iron (Fe), 5800 t yr(-1) Aluminium (Al), 3500 t yr(-1) Zinc (Zn), 1700 t yr(-1) Copper (Cu), 1600 t yr(-1) Manganese (Mn) and minor quantities of other metals and metalloids. These values represent 37% of the global gross flux of dissolved Zn transported by rivers in to the ocean, and 15% of the global gross flux of dissolved Cu. These metals and metalloids usually sink in the estuarine sediments due to pH and salinity changes. The increase of salinity in the estuary favours the adsorption and trapping of metals. For this reason, the mobility and bioavailability of metals such as Zn, Cd and Cu is higher in sediments located in the area of fresh water influence that in sediments located in the marine influenced area of the estuary, showing a higher percentage of fractionation and bioaccumulation of these metals in the station influenced by the fresh water environment.     

Biochemical composition of sedimentary organic matter in the coral reefs of Lakshadweep Archipelago,Indian Ocean

Surface sediments were collected from the shore and lagoons of Kavaratti, Kadamat Agatti and Pitti islands of Lakshadweep Archipelago during May 2015 and analysed for biochemical composition and quality of organic matter. The biochemical composition of sedimentary organic matter from the entire study area was characterised by the dominance of carbohydrates (CHO) followed by proteins (PRT) and finally lipids (LPD). PRT:CHO ratios were less than 1 and indicated the presence of aged organic matter in the islands. The poor nutritional quality of sediments to support benthic fauna was evident from the values of LPD:CHO ratios. The refractory nature of sediments and less availability of food to benthic source was supported by BPC:TOC ratios. Based on estimated ratios and biopolymeric carbon values, the trophic status of the study area was categorised as oligotrophic.