Natural Swamp Research Articles

MISSING TYPES: OVERCOMING THE TYPOLOGY DILEMMA OF LITHIC ARCHAEOLOGY IN SOUTHEAST ASIA.

In Europe as well as in the Americas, typology of at least some key forms was and still is the basis of relative chronology. For Southeast Asian prehistory, attempts to classify lithic assemblages morphologically and technologically in order to fit them into established stone tool typologies from other parts of the world have not proved to be very useful. Up to now, the formation of a specific regional typology system has failed. Session 1C of the 18 Congress of the Indo-Pacific Prehistory Association at Manila (Fig. 1) wanted to explore the “missing types”-problem and adjacent questions. Is the typological approach not appropriate to the special characteristics and circumstances of lithic industries in Southeast Asia? Why do we know of only a few formal “Asian” types and how did the availability and acquisition of raw material influence lithic technology? Are morphological features of lithic artefacts significant enough at all to establish an acceptable chronology system of lithic periods? How can morphological features of lithic artefacts be linked to geostratigraphy in Southeast Asia? Can non-stratified surface finds contribute to Palaeolithic and Neolithic chronologies in that region? And if we dismiss the typological approach, what are the alternatives? Mirroring the state of discussion in lithic analysis in Southeast Asian archaeology, the contributions of the session covered a broad range of subjects. With his talk titled “River basin archaeology” Israel B. Cabanilla (University of the Philippines) reviewed aspects of early Philippine prehistory and site formation. Palaeolithic sites in the Philippines seemingly date back to 400-500,000 years. While most of the investigated Palaeolithic sites are situated in Northern Luzon and on Palawan Island, Cabanilla focused in his talk on the river basins of the Manila area. In his examination of the vast collection of H. Otley Beyer (1947), a pioneer in Philippine archaeology, and of various surveys of the National Museum conducted since the 1960s by Robert Fox and others, Cabanilla revealed that a major share of lithic artefacts originate from the Manila region and are associated with the tributaries of Manila Bay and Laguna de Bay like Marilao, Pasig and Santa Mesa. In her presentation on “Pleistocene stone tools of New Guinea: a new analysis from the Far East of the Far East”, Susan Bulmer (Auckland, New Zealand) mooted artefacts from New Guinea which have long been ignored. Stone tool assemblages from five excavations in the Central Highlands of Papua New Guinea were restudied: four rockshelters in and near the Wahgi Valley, and one openair site, a natural swamp that was first cultivated at around 10,000 BP. Bulmer focused mainly on Pleistocene axes and axe-like tools and compared the evidence of the Highlands with two other Pleistocene sites, Bobongara and Kosipe, the former found on the former coastline and the latter found high on the edge of the upper mountain forest. The types defined are based on empirical attributes such as size, shape, the position and nature of their working edges, and the wear they exhibit. A provisional chronology of the stone tools has been suggested.

Impact Of Deforestation On Ecosystem: A Case Study Of The Fresh Water Swamp Forest In Onne, Niger Delta Region, Nigeria

The Niger Delta region of Nigeria is endowed with the freshwater swamp forest, which is one of the richest ecosystems of the world. The ecosystem through its species diversities play pivotal role at local and global levels by shaping the environment, and influence local climate conditions. The coastal vegetation has been beleaguered by deforestation at an alarming rate. This paper takes a look at the impact of unregulated and uncontrolled removal of vegetation due to human economic activities in Onne freshwater swamp forest. In this study, the mean area of land covered by flood waters was 0.55 ha for the deforested land compared to the non-deforested land which had a mean of 0.25 ha. Similarly, the mean air temperature for the deforested portion was 28.48 0 C while that of the non-deforested area was 23.47 0 C respectively. This study revealed that the rate of deforestation of the natural freshwater swamp forest in Nigeria has led to situation whereby the rich ecosystem is threatened by devastating floodwaters and rising air temperatures.

Forest Dynamics of Peat Swamp Forest in Sebangau, Central Kalimantan

plots. The plots were set up in natural peat swamp forest in the upper catchments of Sebangau, Central Kalimantan. Aim of the study is to understand the dynamics and vegetation changes of forest studied during period of study. The peat swamp forest in the study site might be categorized as moderately forest dynamic in term of rate of growth, mortality and recruitment. Annual relative growth rate and mortality rate was comparable to previous study but recruitment rate relatively higher. There was significant effect of diameter class on annual growth rate, but not to mortality rate. Even not too strong two environment factors (peat depth and distance to river) were significant correlated with rate of mortality and recruitment. During two-year period study there was no significant changes in vegetation structure.Key words: Central Kalimantan, dynamic, growth, mortality, peat swamp forest, recruitment, Sebangau.

Effect of Logging Operation on Soil Carbon Storage of a Tropical Peat Swamp Forest

Problem statement: Since heavy machinery are used in the logging operation activity for extracting the logs on sensitive forest site with peat soil, environment destruction should be the other concern during its processes especially on its important function as soil carbon storage. The objective of this study was to determine whether logging operation affect soil carbon storage of a tropical peat swamp forest. Approach: Soil sampling was conducted before and after logging operation in a 0.3 ha plot to a depth of 15 cm. The soil samples were analyzed for acidity, organic matter content, total carbon, total nitrogen and total phosphorus. The humic acid extraction was also done and soil carbon storage values were obtained by calculation. Paired t-test was used to compare variables under the two treatments (before and after logging) and correlation analysis was used to correlate variables such as soil pH, soil organic matter, total carbon, total nitrogen, total phosphorus, C/N ratio, C/P ratio, humic acid yield, unstable carbon and stable carbon. Results: The availability of unstable carbon and stable carbon controlled by soil acidity on undisturbed peat swamp forest as a result, the accumulation of unstable carbon as well as stable carbon occurred even if the soil pH declines and vice versa. However, stable carbon associated well with soil acidity. It was found that the C/P ratio positively correlated with humic acid and stable carbon of both before and after logging conditions. Nevertheless, that association was prominent on logged peat swamp forest. An indication that even though this peat swamp forest had been logged, humification was strongly maintained. However, the similarity of stable carbon of the logged peat swamp forest with stable carbon of undisturbed peat swamp forest indicate an ineffectiveness humification of logged peat swamp forest. Conclusion: Logging operation on sensitive forest with peat soil using heavy machinery increased the bulk density because of compaction. Soil acidity has important role in preserving soil carbon storage of this natural peat swamp forest, especially stable carbon. After the peat swamp forest is logged, humification processes are strongly maintained but slows and becomes ineffective, hence unstable carbon decomposes more instead of it being preserved as stable carbon. Disturbance by logging operation does not alter their amount of soil carbon storage (stable carbon) due to the carbon in humic acid is quite stable within one year.

Floodplain Characteristics of the Mekong Delta in Cambodia

The purpose of this study was to examine the floodplain characteristics of the inner Mekong Delta, on the lower part of the Mekong River in Cambodia. Previous works have not investigated the floodplain characteristics of the fluvial dominated area of the Mekong Delta. To grasp the morphology of the study area, we first constructed topographical profiles from hydrologic maps and Space Shuttle Radar Topography Mission 3 data. Then, focusing on the morphology of the floodplain, we produced a land classification map based on aerial photo interpretation and field survey and identified the morphological structures of the study area. We classified the delta landforms as natural levee, back marsh, abandoned channel, alluvial terrace, swamp, point bar, and artificial landforms, including colmatages. We identified four floodplain zones. Zone A floodplains, along the upper part of the Mekong River, have cut-off point bar patterns. Those in zone B, along the lower part of the Mekong River, are linear, and develop back marsh widely. In zone C, along the Bassac River, the floodplains follow the river meanders, and are characterized by unevenly distributed artificial colmatages. Floodplains in zone D, along the Tonle Sap River, which has an extremely low gradient, display a unique geomorphology caused by seasonally reversed river flows.

Responses of Alnus glutinosa to Anaerobic Conditions ‐ Mechanisms and Rate of Oxygen Flux into the Roots

Upon exposure to waterlogged growing conditions two-year-old alder trees reduced total root mass. Roots were concentrated in the uppermost soil horizon, and only few coarse roots penetrated into deeper soil layers. Root porosity was only slightly affected and did not exceed 8 % in fine roots. Porosity of coarse roots was higher (27 %) but unaffected by growing conditions. The stem base area covered by lenticels increased strongly and so did the cross section diameter of the stem base. The latter showed a highly significant correlation with O (2) transport into the roots, measured by a Clark type oxygen electrode. Exposure of the lower 5 cm of the stem base, where lenticels were concentrated, to pure N (2) led to a cessation of O (2) transport, confirming that lenticels were the major site of air entry into the stem. In alder plants grown under waterlogged conditions, temperature had a pronounced effect on O (2) gas exchange of the root system. The temperature compensation point, i.e., the temperature where O (2) transport equals O (2) consumption by respiration, was 10.5 degrees C for the entire root system, when measured in a range of 0.15 - 0.20 mmol dissolved O (2) L (-1), which is typical for an open water surface equilibrated with air. O (2) net flow was inversely related to O (2) concentration in the rooting media, indicating that higher root and microbial respiration induced higher net fluxes of O (2) into the root system. With 0.04 mmol dissolved O (2) L (-1) nutrient solution, the temperature compensation point increased to 20 degrees C. Measurement of O (2) gradients in the rhizosphere of agar-embedded roots using O (2) microelectrodes showed a preference for O (2) release in the tip region of coarse roots. Increasing stem temperature over air temperature by 5 degrees C stimulated O (2) flux into the roots as suggested by the model of thermo-osmotic gas transport. However determination of stem and air temperature in a natural alder swamp in northern Germany revealed that within the experimental period of almost one year, temperature gradients required for thermo-osmotic gas transport were very seldom. From this it is concluded that under natural conditions in northern Germany, oxygen diffusion along the stem into the root system is driven by O (2) concentration gradients rather than by thermo-osmosis.

The oasis expansion and eco-environment change over the last 50 years in Manas River Valley, Xinjiang

The oasis expansion and economic development of the Manas River Valley is one of the most successful examples in Xinjiang. In this paper, the oasis spatial distribution pattern and dynamic change were examined using imageries of Landsat MSS, TM and ETM, land use and topographic maps in six different periods (such as 1949, 1962, 1976, 1989, 1999 and 2001) over the last 50 years in the valley. The oasis expansion process could be divided into two stages according to the annual rate of oasis area increase, the fast oasization stage (from 1949 to 1976) when the oasis area expanded from 156.385 km2 in 1949 to 3,639.491 km2 in 1976 because of rapidly increased population and quickly enlarged farmland area; and the urbanization stage (from 1976 to 2001) when the expansion ratio of farmland slowed down, and the urbanization process quickened, the total oasis area reached 5042.440 km2 in 2001. With the continuous expansion of oasis and farmland, a large quantity of river water was drawn into irrigation ditch and plain lakes, so only a small quantity of river water could flow into lakes, as a result, the Manas Lake dried up, salization and basification problems happened in the low-lying oasis region. The natural swamp around the lake was shrunk greatly and biodiversity decreased significantly. The driving force analysis reveals that human activities, such as reclamation and population growth, played a major role in the oasis expansion and ecological deterioration in the Manas River Valley. So further efforts should be made to improve the efficiency of water resource utility and adjust layout of the regional agricultural and animal husbandry to keep the sustainable development of oasis economic belt of the northern slope of Tianshan Mts.

ASSOCIATION BETWEEN LAND COVER AND HABITAT PRODUCTIVITY OF MALARIA VECTORS IN WESTERN KENYAN HIGHLANDS

We examined the effects of land cover type on survivorship and productivity of Anopheles gambiae in Kakamega in the western Kenyan highlands (elevation = 1,420-1,580 meters above sea level). Under natural conditions, An. gambiae sensu lato adults emerged only from farmland habitats, with an estimated productivity of 1.82 mosquitoes/meter(2)/week, but not from forest and swamp habitats. To determine the effects of intraspecific competition and land cover types, semi-natural larval habitats were created within three land cover types (farmland, forest, and natural swamp), and three different densities of An. gambiae sensu stricto larvae were introduced to the larval habitats. The mosquito pupation rate in farmland habitats was significantly greater than in swamp and forest habitats, and larval-to-pupal development times were significantly shorter. At higher densities, the larvae responded to increased intraspecific competition by extending their development time and emerging as smaller adults, but initial larval density showed no significant effects on pupation rate. Land cover type may affect larval survivorship and adult productivity through its effects on water temperature and nutrients in the aquatic habitats, as shown by the significantly higher water temperature in farmland habitats, enhanced pupation rates and shortened development times from the addition of food to habitats, and a significant negative correlation of the occurrence of An. gambiae larvae with canopy cover and emergent plants in natural habitats. These results suggest that deforestation and cultivation of natural swamps in the western Kenyan highland create conditions favorable for the survival of An. gambiae larvae, and consequently increase the risks of malaria transmission to the human population.

Postnatal ontogeny, population structure, and extinction of the giant moa Dinornis

Recent reinterpretation of the giant moa Dinornis as consisting of two sexually dimorphic allospecies permits thorough site-by-site investigation of the ontogeny and population biology of this genus. Analysis of subadult skeletal material from natural swamp sites in the North and South Islands of New Zealand forms the basis for recognition of growth series for each long bone element, characterized by sequential formation of fossulae in the femur and fusion of bones in the tibiotarsus and tarsometatarsus. Femora reached progressive developmental stages more rapidly than the other long bones, but all three elements reached maturity at about the same time. Patterns of bone fusion in Dinornis are more similar to those in Apteryx than in Struthio, and kiwi are recognized as a suitable developmental analog for interpreting moa ontogeny. Samples from Bell Hill Vineyard Swamp (South Island) and Makirikiri swamp (North Island) are interpreted as representing autochthonous moa populations; comparison with stages of kiwi long bone development suggests that Dinornis at these sites had high adult survivorship in strongly K-selected populations, with 72.5-87.3% of individuals having achieved adult body mass, and 55.9-78.2% being sexually mature. The pattern of low fecundity and probable high longevity in both Dinornis species suggests that populations were vulnerable to loss of adults, primarily through hunting, rather than as a result of habitat destruction.

Técnicas de cultivo de arroz irrigado: relação com a qualidade de água, protozoários e diversidade fitoplanctônica

O efeito de técnicas de cultivo do arroz irrigado sobre a qualidade da água efluente foi avaliado através de parâmetros físicos, químicos e biológicos. A pesquisa foi desenvolvida na Estação Experimental do Instituto Riograndense do Arroz (IRGA) no município de Cachoeirinha, RS, bacia do Rio Gravataí. Os testes foram realizados com 3 técnicas distintas e usuais de plantio: convencional, pré-germinado e direto. Constatou-se que, nos primeiros 30 dias de irrigação, os parâmetros medidos dentro dos quadros de plantio apresentaram valores superiores aos da entrada; após este período, a situação se inverteu. Com o crescimento, as plantas de arroz funcionaram como um banhado natural, extraindo da água e do solo uma quantidade significativa de nutrientes, não somente durante sua fase inicial, mas, também, durante todo o seu ciclo. Esses nutrientes foram extraídos do meio líquido, melhorando a qualidade ambiental da água efluente. Dentre todas as técnicas de cultivo, o menor impacto sobre a qualidade da água foi apresentado pelo plantio direto.

Interesting Species of the Laboulbeniales from Upo Swamp

Eight species belonging to two genera of the Laboulbeniales, parasitic on the family Carabidae and Staphylinidae of the order Coleoptera, were collected from Upo natural swamp in 1996-2001. They are as follows; Laboulbenia anoplogenii parasitic on Platynus daimio, L. cristata on Paederus parallelus, L. egens on Tachys laetifica, L. flagellata on Platynus daimio, L. pedicellata on Bembidion morawitzi, L. philonthi on Philonthus wuesthoffi, L. stenolophi on Acupalpus inornatus and Philonthus longicornis, and Peyritschiella biformis on Philonthus micaticollis. Among these species, the genus Platynus as the host of L. anoplogenii and the genus Acupalpus as the host of L. stenolophi are new to science. Bembidion morawitzi as the host of Laboulbenia pedicellata and Philonthus micanticollis as the host of Peyritschiella biformis are new to Korea.

A Water Chemistry Assessment of Wastewater Remediation in a Natural Swamp

AbstractVarious aspects of water chemistry of a natural forested wetland were studied in order to determine the possibility of using the wetland for advanced wastewater treatment in Louisiana and to evaluate the wastewater effect on swamp water quality. The study was carried out by comparing treatment and control cypress‐tupelo forests separated by a bottomland hardwood forest ridge. The treatment area (231 ha) received secondarily treated municipal wastewater at a rate of 6.3 × 106 L d−1. The calculated hydraulic detention time of the wastewater was 120 d. Electrical conductivity (EC), pH, and concentrations of 5‐d biological oxygen demand (BOD5), dissolved oxygen (DO), solids, nutrients, and trace metals were monitored. Mean concentrations for the wastewater were 14.6 mg L−1 for total N and 2.5 mg L−1 for total P. The dominant form of N in the wastewater was NO3‐N. The swamp system attenuated the NO3‐N by 100%, total Kjeldahl nitrogen (TKN) by 69%, and total P by 66%. It appears that tertiary wastewater treatment was achieved due to the nutrient attenuations. Based upon our findings, we predict that the high N attenuation efficiency would enable the swamp to work well if the N loading rate were doubled. However, P removal was dependent on loading rate, hydraulic retention time, and temperature. The swamp was more efficient in treating wastewater during warm seasons than cool seasons. During the monitoring period, trace metals were not significantly increased in the swamp water because of very low concentrations in the wastewater.

Mercury in the River Nura and its floodplain, Central Kazakhstan: II. Floodplain soils and riverbank silt deposits

A unique and serious case of mercury pollution has occurred in the River Nura and its floodplain in Central Kazakhstan, where mercury-rich wastewater from an acetaldehyde plant was discharged largely without treatment for several decades. In the river, the mercury became associated with millions of tonnes of power station fly ash, forming a new type of deposit known as ‘technogenic silt’. During spring floods these highly contaminated silts are transported downstream and are dispersed over the floodplain, leading to widespread contamination of the land. A detailed survey of the floodplain was carried out to investigate the extent of pollution and to assess the need for remediation. Total mercury concentrations in the topsoils of the floodplain ranged from near background levels to over 100 mg/kg. Mercury concentrations in river bank deposits were found to range from a mean of 73.3 mg/kg Hg in the most contaminated section of the river to a mean of 13.4 mg/kg Hg at a distance of 70 km downstream. Concentrations were lower than corresponding concentrations in the riverbed within the first 25 km from the source of the pollution, but thereafter they were significantly higher. The results show that over the past 30–40 years a large proportion of the contaminated sediments from the river was deposited on the 70 km of banks and in the floodplain below the pollution source. Topsoils of the floodplain and silt deposits located on or close to the river banks contain an estimated 53 t and 65 t of mercury respectively, with an additional 62 t in a small natural swamp which was formerly used as a waste disposal area. The contamination is serious but relatively localized, with >70% of the total amount of mercury in topsoils and >90% of mercury in river bank deposits located within 25 km from the source.

Influences of Deforestation on Carbon Balance in a Natural Tropical Peat Swamp Forest in Thailand.

The effects of deforestation on carbon balance in a natural tropical peat swamp forest were evaluated by micrometeorological monitoring. The monitoring sites were the primary forest at To-Daeng and the secondary forest at Bacho in Narathiwat Province, Thailand. The concentration gradient method (CG) and the relaxed eddy accumulation method (REA) were used to estimate the CO2 flux above the canopies. We estimated the annual amount of carbon absorption for both sites, using the relationship between CO2 flux and solar radiation for each site. An annual net carbon absorption of 5.32t C ha-1 year-1, was estimated for the primary forest. The accumulation of the released organic matter from the forest into logged-water caused the net carbon absorption in the peat swamp forest. In the secondary forest, annual net carbon absorption was estimated at 5.22 t C ha-1 year-1, which is almost the same range of absorption as the primary forest, because of plant growth in the secondary forest. A greater quantity of net carbon absorption, 9.69t C ha-1 year-1, was expected, assuming that the ground surface remained water-logged throughout the year. On the other hand, assuming it remained dry throughout the year, a net carbon emission of -0.40 t C ha-1 year-1, was expected.

Gill-Cleaning Mechanisms of the Crayfish Procambarus clarkii (Astacidea: Cambaridae): Experimental Testing of Setobranch Function

Gills of the crayfish Procambarus clarkii are cleaned by two sets of setae which are thrust back and forth among gill filaments by feeding, locomotory, or other movements of thoracic legs. Setae with a complex, rasping microstructure arise from papillae (setobranchs) on the third maxillipeds and pereopods 1-4, and extend up between the inner layer of arthrobranch and outer layer of podobranch gills. The lateral sides of the podobranchs, beyond the range of the setobranch setae, are penetrated by a field of setae projecting from the inner side of the gill cover. These branchiostegal setae bear digitate scale setules like those borne by the setobranch setae. Although cleaning setae act concomitantly with any type of leg movement, these animals engage in a previously unreported behavior, limb rocking, whose sole function appears to be gill cleaning. The effectiveness of cleaning setae was tested with experiments in which setobranch setae were removed from the branchial chamber of one side but not the other. Treated crayfishes set out in commercial ponds and a natural swamp habitat suffered heavy particulate fouling on gill filaments deprived of setobranch setae. The pattern of fouling showed that branchiostegal setae also prevented particulate fouling. However, gill-cleaning setae were not effective against bacterial or ciliate fouling. It is concluded that molting is the only escape from epibiotic fouling

Habitat qualities versus long-term continuity as determinants of biodiversity in boreal old-growth swamp forests

Natural swamp forests are extremely rare in Sweden because of extensive drainage and logging activities. This study reports a total of 517 species (148 vascular plants, 131 mosses, 64 hepatics, 142 lichens and 32 wood-inhabiting fungi) from 10 small remnants of boreal old-growth swamp forests. The 195 bryophytes found represent 33% of the total number of bryophyte species in the Swedish boreal flora. As the average area of the forests was only 2ha, this figure clearly illustrates the important role of the swamp forests as centres of bryophyte biodiversity.There was no relationship between the occurrence of 33 lichen and fungi species considered to indicate natural forests with long stand continuity and the known long-term continuity of the forests. The forests most affected by earlier natural and man-made fires harboured more of these species than forests less affected by fire disturbance. The most important variable explaining biodiversity as well as presence of ‘continuity indicator species’ was the amount of dead wood present. A more critical and careful use of the concept of forest continuity is needed.

Nutritional Environment of Tropical Peat Soils in Sarawak, Malaysia Based on Soil Solution Composition

Abstract It has been considered that natural peat soils and swamp forest ecosystems in the tropics are quite oligotrophic. This concept seems to be related to the low mineral contents in the soil solid phase of the peat soils. However, some nutritional elements such as K, Mg, Ca, and/or P may be abundant in the soil solution phase and could easily migrate in peat soils. In order to analyze the nutritional environment of peat soils, chemical composition of the soil solid phase and soil solution was compared. This study was carried out in Naman Forest Reserve, Sibu and in/around Sg. Talau Peat Research Station, Mukah, Sarawak, Malaysia. In both areas, each of the three study sites with a different depth of underlying mineral layer was selected for sampling of soil and soil solution. All the soils studied except for one shallow peat profile were classified into Oligotrophic peat based on Fleischer’s criteria. The soil solution collected monthly showed the following characteristics in its composition. 1. Conc...

Assemblages of dytiscid predators and culicid prey in relation to environmental factors in natural and clear-cut boreal swamp forest pools

Assemblages of diving beetles (Dytiscidae) and mosquito immatures (Culicidae) were studied during 1987–1988 in 40 small, more or less temporary, snowmelt pools in spruce swamp forest and clearings at the Arctic Circle in Sweden. Larger pools were warmer than smaller ones, and clearing pools were warmer than forest pools. Temperature differences between pools remained high until late July. Twenty-one dytiscid species, representing three guilds, occurred in the pools, and individual pools had 1–13 species. Ten species occurred in both habitats. A few stenotopic species of boreal swamp forests had in clearing pools apparently been replaced by some species with a preference for more productive, often man-made habitats. Six Aedes species were collected in the clearing pools. Five of these were found in the forest pools, of which three had no mosquito larvae. Dytiscid assemblages in both habitats and culicid assemblages in clearing pools showed strong nested patterns.

Growth and reproduction of the cladoceran Ceriodaphnia dubia from a forested floodplain swamp

Microcrustaceans are abundant in many freshwater wetlands, including forested floodplain swamps, but little has been done to assess their secondary production and functional role in these systems. Since standard cohort approaches to estimating secondary production are impossible with continuously growing and reproducing microcrustaceans, it is necessary to obtain independent determinations of their growth and reproductive characteristics under environmental conditions encountered in their natural habitat throughout the year. The growth and reproduction of Ceriodaphnia dubia fed natural swamp seston were measured at 10, 15, 20, and 25°C—temperatures which span much of the annual temperature range in southeastern floodplain swamps. Somatic biomass growth rates were as high as 61% d−1. Total growth rates (somatic tissue and egg mass) reached 95% d−1. Both somatic growth rates and total growth rates could be described as functions of individual size and temperature. High egg production, particularly in the larger instars, resulted in individuals maintaining high total growth rates (>20% d−1 at most temperatures) over the lifespan. Lifetime egg production accounted for >50% of biomass produced by individuals at all temperatures and >80% for temperatures ≥20°C. Somatic growth rates for C. dubia fed swamp seston were within the range of literature estimates for other species of Ceriodaphnia under various food conditions.

Distribution of heavy metals among different bonding forms in tropical peat soils

Abstract The objective of this study is to analyze the characteristics of the macro- and micro-nutrient status of tropical peat soils under natural swamp forest and their changes after reclamation. We sampled peat soils from the coastal swamps in southern Thailand and southern Peninsular Malaysia. These soils were at varying stages of reclamation. Soil Fe, Mn, Zn, and Cu were sequentially divided into water soluble, Ca exchangeable, free-oxide-associated, weakly complexed, strongly complexed, carbonate-associated, and sulfide-associated extractable forms. Peat soils sampled in Malaysia were classified into Oligotrophic peat soils due to their low N, P, K, and Ca contents. The Ca, Mg, K, and Na contents did not change appreciably with the soil depth, though the Mn, Zn, and Cu contents decreased with the soil depth down to 30 cm and subsequently the decrease was negligible. Based on the analysis of the distribution of the metal forms, most of Cu and Fe occurred in strongly chelated and non-extractable forms. Average contents of water soluble and Ca exchangeable forms (intensity factor) of Mn, Zn, and Cu were 12, 4, and < 0.1 mg kg-1 of soils, respectively. In the case of fertilized soil (experimental field of MARDI), heavy metal contents of the surface soil were about 3 to 15 times as high as those of the subsoil. Most of the increment occurred in the weakly chelated, strongly chelated, or non-extractable forms, because the pH of the surface soil was higher than that of the subsoil. As the chelating effect of humic substances is likely to be pronounced for a high soil pH, heavy metals applied in fertilizers were changed into non-available forms. Adsorption strength of humic substances in peat for metal ions was as follows: Cu > Fe > Zn > Mn.