Local Macrophyte Research Articles

HEAVY METALS AND CONTAMINATION PARAMETERS REMOVAL BY DIFFERENT PLANT FROM WASTEWATER IN HYBRID CONSTRUCTED WETLANDS

Water is essential requirement for every living creature on our planet to grow and prosper. The progress expansion and increased population of Sulaimani city caused increased in water demand and need for reusing of waste water for irrigation. This study aims to remove some waste water heavy metals and parameters by root and shoot of Macrophytes in Hybrid Constructed wetlands (HCW). HCW are designed as (Vertical-Horizontal and Horizontal-Vertical) along with sand filtration implemented with two local Macrophytes (Typha angustifolia and phragmate australis). The plant root and shoot were analyzed in beginning and end of the study to determine the removal rate. The result shows increase in the mean concentration values of heavy metals and waste water parameters in root and shoo of both T. angustifolia and Ph. australis in HCW (H&V) and (V&H). Therefore, Macrophytes in HCW can be used to remove heavy metals and other parameters from waste water used for irrigation.

The Beautiful and the Dammed: Defining Multi-Stressor Disturbance Regimes in an Atlantic River Floodplain Wetland

Natural hydrological fluctuations within river floodplains generate habitat diversity through variable connections between habitat patches and the main river channel. Human modification of floodplains can alter the magnitude and frequency of large floods and associated sediment movement by interrupting these floodplain connections. The lower Wolastoq | Saint John River and its associated floodplain wetlands are experiencing anthropogenic disturbances arising from climate change, increased urbanization in the watershed, changing upstream agricultural landscape practices, and, most notably, major road and dam construction. By comparing digitized aerial images, we identified key periods of change in wetland extent throughout an ecologically significant component of the floodplain, the Grand Lake Meadows and Portobello Creek wetland complex, with significant erosion evident in coves and backwater areas across the landscape following dam construction and significant accretion around the Jemseg River following highway construction. Connectivity and hydrological regime also influenced other habitat components, namely nutrients and metals retention, as well as the composition of the local macrophyte community. These findings address two key aspects of floodplain management: (1) understanding how hydrological alteration has historically influenced floodplain wetlands can inform us of how the ecosystem may respond under future conditions, such as climate change, and (2) the mechanisms by which habitat diversity and disturbance regimes filter biological communities, with the potential for patches to host a rich biodiversity continuously supporting critical ecosystem functions.

Absorption of Lead and Mercury in Dominant Aquatic Macrophytes of Balili River and Its Implication to Phytoremediation of Water Bodies.

In the Philippines, phytoremediation studies on heavy metals are mainly concentrated in mining areas amidst several reports of heavy metal contamination even in non-mining sites in various parts of the country. Such was the case Balili River which was reportedly contaminated with mercury (Hg) and lead (Pb). Aquatic macrophytes growing in the river could offer the solution to this problem via phytoremediation. Thus, this study was conceptualised to determine the uptake of Hg and Pb in selected dominant macrophytes of the river namely Amaranthus spinosus, Eleusine indica and Pennisetum purpureum. Soil, water and plant samples gathered from the study sites were submitted to Department of Science and Technology-Cordillera Administrative Region (DOST-CAR) laboratory for Hg and Pb determination. Soil and wastewater of Balili River were found contaminated with Pb but not with Hg. The soil recorded higher Hg concentration than water while Pb concentrations did not differ between the two media. The aquatic macrophytes in the study registered consistently higher Hg and Pb in their shoots > roots but differed in their capacities and distribution in the shoot organs. Hg and Pb accumulation was significantly (p = 0.00) higher in stem of P. purpureum while in E. indica, leaf had the highest accumulation, though not statistically significant (p = 0.09). For A. spinosus, Hg was highest in its leaf while Pb in stem, though not statistically significant (p = 0.06). Among the three macrophytes, P. purpureum showed the highest potential for Hg uptake and translocation and for Pb uptake. On the other hand, the highest Pb internal transfer was recorded in E. indica. These results contradict initial findings that Pb is mostly accumulated in plant roots with minimal shoot translocation. Also, these results show that local macrophytes in Balili River, even if obnoxious weeds, are ecologically important and could be used for phytoremediation of local rivers that are recipient of small-scale mine tailings.

A novel integrative performance evaluation of constructed wetland on removal of viable bacterial cells and related pathogenic, virulent and multi-drug resistant genes from wastewater systems

Integrative performance evaluation of constructed wetland in removal different aspects of bacteria under specific local environmental conditions needs to be explored in detail to ensure selection of appropriate and highly efficient macrophytes candidates. To achieve this, integrative purification performance evaluation approach that holistically considers all the aspects of pathogenic bacterial biology (colony numbers, functional gene, species, virulent, pathogenicity and resistant genes) needs to be adopted rather than the commonly known unidimensional approaches that take into account a single bacterial aspect. This study experimentally evaluated the individual performance of three native and one exotic winter tolerant submerged macrophytes combined with a single emergent macrophyte in eradicating faecal related bacterial species and pathotypes across horizontal surface flow constructed wetland. It involved the new multi-dimensional approach that integrated the faecal bacterial colony numbers, functional gene copies, species survival, virulent and pathogenicity as well as antimicrobial resistant in constructed wetland purification evaluation. The results showed Elodea nuttallii and Myriophyllum spicatum as the best candidate partners to Typha latifolia for the highest Purification Efficiency (P < 0.05), of above 97% for removal of faecal bacteria colonies and functional genes, and more than 75% for removal of faecal bacterial strains, pathotypes, virulent and well as resistant genes. However, M. spicatum being a Chinese native species should be much preferred to the invasive E. nuttallii. Therefore, the study recommends the application of local macrophytes such as M. spicatum as the best candidates and the decision should emanate from such a multidimensional/intergrative purification-based evaluation approach.

Treatment of Balili River in Benguet, Philippines with constructed wetland planted with dominant local macrophytes

Phytoremediation using local macrophytes was explored in Balili River, Philippines. The macrophytes used were Amaranthus spinosus, Eichhornia crassipes, Eleusine indica and Pennisetum purpureum planted in pilot-scale constructed wetlands and subjected to varying hydraulic retention time (HRT) treatments. Results showed that these macrophytes have high phytoremediation performance in almost all water quality parameters. Also, HRT significantly affected the pollution reduction efficiency of the macrophytes. Significant pollution reduction was observed as early as HRT 1 day, but the optimal HRT for all the macrophytes was 3–4 days. At optimal HRT, the pollution reduction efficiency of the four macrophytes ranged from 96% to 99.9% for TSS, 87% to 95% for BOD, 85% to 99% for NO3, 85% to 96% for PO4 and 99.9% for total and fecal coliform. Also, Hg and Pb were significantly reduced. Results of TSS, DO and NO3 passed the water quality standard, while BOD and PO4 were slightly above. But total and fecal coliform, amidst the high reduction rate, was still not within the permissible level for Class A water. Among the macrophytes, P. purpureum generally have the best pollution reduction efficiency. Our study revealed comparable or even better pollution reduction efficiency of local macrophytes than commonly used ones such as Phragmites spp. and Typha spp.

Using Ipomoea aquatic as an environmental-friendly alternative to Elodea nuttallii for the aquaculture of Chinese mitten crab.

Elodea nuttallii is widely used in Chinese mitten crab (CMC) rearing practice, but it is not a native aquatic plant and cannot endure high temperature. Thus, large E. nuttallii mortality and water deterioration events could occur during high-temperature seasons. The aim of this study was to identify the use of local macrophytes in CMC rearing practice, including Ipomoea aquatic and Oryza sativa. A completely randomized field experiment was conducted to investigate the crab yield, water quality, bacterioplankton community and functions in the three different systems (E. nuttallii, I. aquatic, and O. sativa). Average crab yields in the different macrophyte systems did not differ significantly. The I. aquatic and O. sativa systems significantly decreased the total nitrogen and nitrate-N quantities in the outflow waters during the rearing period compared to the E. nuttallii system, and the I. aquatic and O. sativa plants assimilated more nitrogen than the E. nuttallii plant. Moreover, the significant changes of bacterioplankton abundances and biodiversity in the three systems implied that cleanliness of rearing waters was concomitantly attributed to the differential microbial community and functions. In addition, principle component analysis successfully differentiated the bacterioplankton communities of the three macrophytes systems. Environmental factor fitting and the co-occurrence network analyses indicated that pH was the driver of bacterioplankton community structure. Functional predictions using PICRUSt (v.1.1.3) software based on evolutionary modeling indicated a higher potential for microbial denitrification in the I. aquatic and O. sativa systems. Notably, the O. sativa plants stopped growing in the middle of the rearing period. Thus, the I. aquatic system rather than the O. sativa system could be a feasible and environmental-friendly alternative to the E. nuttallii system in CMC rearing practice.

Diversity of aquatic macrophytes in Balili River, La Trinidad, Benguet, Philippines as potential phytoremediators

Abstract. Napaldet JT, Buot JR IE. 2019. Diversity of aquatic macrophytes in Balili River, La Trinidad, Benguet, Philippines as potential phytoremediators. Biodiversitas 20: 1048-1054. Phytoremediation, an emerging, low-cost, aesthetically pleasing technology, is now being eyed for restoration of Balili River, Philippines. But first, there is a need to identify plants ideal for its phytoremediation. Macrophytes in the main stream, Bolo Creek and Mamaga Creek of Balili River were inventoried in this study with focus on determining macrophytes that were local, dominant (=fast growing), have high biomass and deep root systems – traits ideal for phytoremediation. A total of 38 species of macrophytes under 37 genera and 19 families were inventoried. This number is much higher than the previous inventory which recorded only 9 species. Consequently, diversity indices recorded in this study is much higher. The difference could be attributed to the time of sampling wherein the previous inventory was done in July, a rainy month, in contrast with this in April, the summer month at which the river is at its lowest level. At this period, much of the littoral zone is exposed for colonization of plants known to be easily dispersed and germinate such as Asteraceae species. In terms of species richness, family Asteraceae was the most represented with 11 species but in terms of dominance, the story was different. Dominant macrophytes of Balili River were species of family Poaceae (Pennisetum purpureum, Eleusine indica and Cynodon dactylon), Amaranthaceae (Amaranthus spinosus and Alternanthera sessilis), Solanaceae (Solanum americanum) and Commelinaceae (Commelina diffusa). Local macrophytes with potential for phytoremediation were P. purpureum, E. indica, A. spinosus and S. americanum.

Use of macrophyte plants, sand & gravel materials in constructed wetlands for greywater treatment

Greywater discharged without any treatments into drainage channels or natural water bodies will lead to environmental degradation and health risk. Local macrophyte plants combined with natural materials of sand and gravel have been used in a system of constructed wetland for the treatment of the greywater. This paper presents the results of some studies of the system carried out in Indonesia, Thailand, and Costa Rica. The studies demonstrate the success of the constructed wetland systems in removing some pollutants of BOD, COD, TSS, pathogen, and detergent. The studies resulted in the treated water in a level of treatment that fulfils the requirement of the local standards for wastewater reuse as irrigation water, fishery, or other outdoor needs.

Comparison between Vertical-Horizontal and Horizontal-Vertical hybrid constructed wetlands.

Water pollution cause serious health risk to public. Treating wastewater in allow cost&#x0D; efficient way is necessary for the region. This project was designated to describe the&#x0D; usefulness of macrophytes Typha angustifolia L and Phragmites australis, since this could&#x0D; be an index for its utility as a biological purifier for advanced treatment of wastewater.&#x0D; For this purpose a specific model treatment project was hybrid constructed wetland.&#x0D; Constructed wetlands have become a good alternative to urban wastewater treatments. To&#x0D; achieve higher treatment performances, the HCW has various types. The project consists&#x0D; of several purification treatment units; Storage tanks, pre-sedimentation and two hybrid&#x0D; constructed wetlands. They are designed as (Vertical-Horizontal and Horizontal-Vertical)&#x0D; HCW, along with sand filtration implemented with two local macrophytes (Typha&#x0D; angustifolia and Phragmites australis). Experimental hybrid constructed wetlands contain&#x0D; macrophytes, they have grown for 50 days (the period needed for stabilization and&#x0D; adaptation), and taken untreated and treated wastewater samples twice a month periods&#x0D; from June 15, 2013 until September 15, 2013. Water samples were analyzed to determine&#x0D; the some heavy metals in inlet and outlet HCW. Results showed that the decreases in Iron,&#x0D; Copper, Cadmium and Lead contents in the outlet wastewater treatment in (Vertical-&#x0D; Horizontal) HCW higher decreases than (Horizontal-Vertical) HCW. These results&#x0D; showed the design (Vertical-Horizontal) HCW better than the design (Horizontal-&#x0D; Vertical) HCW to wastewater treatment.

Sustainable Use Of Macro-Algae For Biogas Production In Latvian Conditions: A Preliminary Study Through An Integrated Mca And Lca Approach

Abstract The study focuses on sustainability evaluation of an algae-based energy system in Latvia with a holistic and integrated approach of multi-criteria analysis combined with life cycle assessment (including a practical side - biogas yield experiments of locally available algae). The study shows potential for sustainable use of algae in Latvian conditions and thus that algal biomass can be utilized for the production of biogas. The most sustainable and feasible scenario of using algae for biogas energy production foresees the collection of algae biomass from natural water bodies. Important beneficial effects through the use of algae are related to avoiding global warming potential (GWP) and eutrophication impacts. Biogas batch experiments carried out with the local macrophyte C.demersum have shown a methane yield of 554 l CH4/kg VS.

Is stocking barramundi (Lates calcarifer) in north-eastern Queensland a threat to aquatic biodiversity?

The stocking of predators can have significant consequences on recipient aquatic ecosystems. We investigated some potential ecological impacts of stocking a predatory fish (Lates calcarifer) into a coastal river and a large impoundment in north-eastern Australia. L. calcarifer was mostly found in slower-moving, larger reaches of the river or in the main body of the impoundment where there was abundant suitable habitat. In the tidally influenced freshwater reaches of the coastal river, L. calcarifer predominately consumed aytid and palaemonid shrimp that were associated with local macrophyte beds or littoral grasses. In this area the diets of juvenile stocked and wild L. calcarifer were similar and stocked fish displayed a high degree of site fidelity. Further upstream in the river, away from tidal influence, and in the impoundment, fish were the main prey item. Cannibalism was uncommon and we suggest that, at the current stocking densities, there was little dietary evidence of predatory impacts from L. calcarifer on species of conservation concern. We caution against introducing novel predatory species such as L. calcarifer in or near areas that are outside their natural range and are known to support rare, threatened or endangered species.

Species pool versus site limitations of macrophytes in urban waters

Biodiversity in urban areas is affected by a multitude of stressors. In addition to physico-chemical stress factors, the native regional species pool can be greatly reduced in highly urbanized landscapes due to area loss and fragmentation. In this study, we investigated how macrophyte composition and diversity in urban water systems are limited by the regional species pool and local environmental conditions. Canonical correspondence analysis of the macrophyte species composition revealed that urban and semi-natural water systems differed and differences could be related to local abiotic variables such as pH and iron concentrations. Macrophytes in the semi-natural area were typical for slightly acid and oligotrophic conditions. In urban water systems, exotic species characteristic of eutrophic conditions were present. In the semi-natural areas, the number of macrophyte species exceeded the number of species expected from species–area relationships of artificial water bodies in rural areas. In urban areas, the number of macrophyte species was similar to artificial water systems in rural areas. Macrophyte species present in the study areas also were generally found within 20–30 km distance to the study area. Macrophyte species composition in urban water systems and semi-natural water systems appeared to be influenced by the regional species pool within approximately 30 km of the locations. Nevertheless, site limitation ultimately determined the local macrophyte species composition and diversity in urban water systems and in semi-natural water systems.

Predicting zebra mussel fouling on native mussels from physicochemical variables

Summary1. Predictive models of impact are needed for the risk assessment of invasive species. One such species is the Eurasian zebra mussel (Dreissena polymorpha), a fouling bivalve that overgrows and kills native mussels (Unionidae) in many North American lakes and rivers. The level of mortality in a native mussel population increases with the fouling intensity – i.e. the mean number of zebra mussels attached to each native mussel.2. We conducted a multi‐site survey within the St Lawrence and Richelieu rivers (Quebec, Canada) to determine whether zebra mussel fouling intensity can be predicted from environmental variables. We found fouling intensity to be positively correlated with calcium concentration [Ca2+] and negatively correlated with sediment size, but not affected by local macrophyte cover.3. A multiple regression model that includes calcium concentration and sediment size explains 86% of variation in fouling intensity across all sites.4. Analysis of data from invaded sites in North America and Europe revealed a nonlinear relationship in which fouling intensity increases with calcium concentration up to an asymptotic threshold of 24 mg L−1 Ca2+.5. Our results suggest that the community‐level impacts of zebra mussels are mediated by abiotic environmental variables and gradients in these variables may provide local habitat refugia for native mussels.

Bacterial carbon sources in coastal sediments: a cross-system analysis based on stable isotope data of biomarkers

Abstract. Coastal ecosystems are typically highly productive, and the sediments in these systems receive organic matter from a variety of local and imported sources. To assess if general patterns are present in the origin of carbon sources for sedimentary bacteria and their relation to the origin of the sediment organic carbon pool, we compiled both literature and new data on δ13C of bacterial biomarkers (the phospholipid derived fatty acids i+a15:0), along with δ13C data on sediment organic carbon (δ13CTOC) and macrophyte biomass from a variety of typical near-coastal systems. These systems included mangroves, salt marshes (both C3 and C4-dominated sites), seagrass beds, and macroalgae-based systems, as well as unvegetated sediments. First, our δ13Ci+a15:0 data showed large variability over the entire range of δ13CTOC, indicating that in many settings, bacteria may depend on carbon derived from various origins. Secondly, systems where local macrophyte production is the major supplier of organic carbon for in situ decomposition are generally limited to organic carbon-rich, peaty sites (TOC&gt;10 wt%), which are likely to make up only a small part of the global area of vegetated coastal systems. These carbon-rich sediments also provided a field based estimate of isotopic fractionation between bacterial carbon sources and biomarkers (-3.7±2.1), which is similar to the expected value of about -3 associated with the biosynthesis of fatty acids. Thirdly, only in systems with low TOC (below ~1 wt%), we consistently found that bacteria were selectively utilizing an isotopically enriched carbon source, which may be root exudates but more likely is derived from microphytobenthos. In other systems with between ~1 and 10 wt% TOC, bacteria appear to show on average little selectivity and δ13Ci+a15:0 data generally follow the δ13CTOC, even in systems where the TOC is a mixture of algal and macrophyte sources that generally are believed to have a very different degradability.

Assimilation efficiency of zinc and cadmium in the decapod crustacean Penaeus indicus

The assimilation of trace metals from food can be the main route of metal uptake into aquatic invertebrates. The assimilation efficiencies of zinc and cadmium from muscle tissue of a cephalopod mollusc (40% to 70% Zn, 64% to 83% Cd) and from a macrophytic alga (50% to 69% Zn, 39% to 50% Cd) were measured in juvenile penaeid prawns Penaeus indicus. Assimilated Zn and Cd were retained mostly in the hepatopancreas of the prawns, some metal being excreted (Zn k e 0.10 and 0.11 and Cd k e 0.004 and 0.009, from cephalopod muscle and alga, respectively). There were no significant differences between k es (efflux rate constants) of one metal from either diet. Given the high trace metal assimilation efficiencies measured here, it is highly probable that metal assimilation from food plays an important role in Zn and Cd accumulation in the body of P. indicus, particularly in estuarine stages of the life cycle, for estuaries are particularly prone to metal pollution and are likely to offer the prawns abundant metal-rich diets such as detrital material derived from local macrophytes.

An evaluation of approaches used to determine the distribution and biomass of emergent and submerged aquatic macrophytes over large spatial scales

We compared the performance of various approaches to determine the distribution and biomass of submerged and emergent aquatic plants in a large fluvial lake. Three empirical models linking local macrophyte biomass to single and multiple environmental variables were applied in a GIS-framework to estimate the spatial distribution and biomass of aquatic macrophytes in Lake St. Pierre, a large (300 km 2), shallow (mean depth: 3 m) and complex widening of the St. Lawrence River (Quebec, Canada). The resulting maps and emergent and submerged macrophyte distributions obtained independently by remote sensing and echo sounding techniques were compared to field data collected in 2000. Maps derived from echo sounding, from a biomass versus depth regression and from a four-variable model (i.e. exposure to wind and waves, plant growth form, water depth and transparency) were the most accurate (55–63% overall agreement with field data). Remote sensing techniques were the least accurate for determining underwater macrophyte distribution in Lake St. Pierre due to the limitations of image-based methods for detecting submerged aquatic vegetation in coloured, turbid waters. This study demonstrates that environmental models in combination with GIS can be used to estimate aquatic macrophyte distribution over larger spatial scales and to examine potential change in macrophyte growth form assemblages arising from different environmental conditions.

The Study on Natural Restoration of Aquatic Vegetation in the Northern Lakeside, Lake Taihu

It has been observed and studied that the natural restoration process of aquatic vegetation in the experimental enclosure of northern lakeside, Lake Taihu, from 1997 to 1999 years. It is found that the local macrophytes, for example, the Nymphoides peltata, Trapa sp. and Potamogeton malainus Mig, can be naturally restored in the bare lakeside of big shallow eutrophication lakes by an enclosed protection methods. The cover area by species of Nymphoides peltata and Trapa sp. has taken up to 14.3% and 12.7% of the total enclosure area in the summer of 1998, respectively. The companion species of vegetation are Potamogeton malainus Mig, Hydrilla verticillata Royle and Vallisneria spiralis L. The affection to the natural restore of macrophytes by anthropologic readping and fish culture has also been discussed. According to the results of enclosure experiment, it has provided a strategy for control of eutrophication in big shallow lakes, for example, Taihu Lake.

The contribution of macrophyte‐derived organic matter to microbial biomass in salt‐marsh sediments: Stable carbon isotope analysis of microbial biomarkers

Stable carbon isotope ratios of bacterial biomarkers were determined to infer sources of organic carbon used by bacteria in the sediments of three salt marshes. Biomarkers studied were polar lipid‐derived fatty acids (PLFA), mainly bacteria‐specific, methyl‐branched i15:0 and a15:0. Experiments showed that isotopic fractionation between substrate and biomarkers was relatively constant (–4 to –6‰, on average) compared to the wide range in 13C/12C ratios of carbon sources found in the studied marshes. At the Spartina site of the Waarde Marsh (The Netherlands), biomarker 13C/12C ratios were depleted by approximately 6‰ more than expected for bacteria growing on Spartina litter and were similar to an unvegetated control sediment. This pattern suggested that local macrophyte production was of little importance and that other material (probably of algal origin) was the dominant carbon source for bacterial growth. Spartina contributed about half of the carbon in bacterial PLFA at the Kattendijke Marsh (The Netherlands) and dominated at the Great Marshes (U.S.). The variation in bacterial carbon sources in these marshes was probably related to estimated inputs of nonmacrophyte organic matter to the sediment. At the Waarde Marsh, a clear plant species effect was found as coupling between plant and bacteria was more important in Scirpus maritimus than in Spartina anglica. The contribution of local plant production to bacterial biomass in salt‐marsh sediments is highly variable between marshes and depends on the input of nonmacrophyte material by sedimentation in comparison to local plant input, which in turn may differ among plant species.

Water quality protection and aquaculture in Yuqiao Reservoir

大水面增养殖将水体中的氮、磷、有机物转化成鱼产品,并以渔获物的形式输出水体,从而加大水体氮、磷、有机物的输出量,有减缓水体富营养化、净化饮水水质的作用;同时鱼类的摄食、消化、排泄等新陈代谢活动可加速水中氮、磷等物质循环,使藻类繁衍,如果大量放养草鱼还会导致水草资源破坏、生态失衡,对饮水卫生、安全不利;网箱养鱼投入饲料,直接增加了水源有机污染。围网养殖对局部水域生态平衡有破坏作用,放养密度过大,投入饲料也会直接增加有机污染。库周鱼塘排水会增加水库氮、磷输入量。为保护水库水质和生态平衡,不要盲目往于桥水库中大量投放草鱼,禁止或限制网箱投饵养鱼和围网养殖。同时建议:保护现有鲤、鲫鱼资源,引进能利用腐屑资源的鲴类鱼,加大鲢、鳙放养规格,适度增殖鳜鱼,利用库中水草和库周鱼塘养殖草鱼,防治库中水草对水库水质的二次污染,同时发展了池塘渔业。;The aquaculture can lighten water eutruphication and improve drinking water quality. But on the other hand, the fish metabulism activities as eating, digest and drain can speed up the cycle velocity of the N, P and organic matter in the waters and accelerate reproduction of algae. If a large number of the grass carp (Cienopharyngodon iadllus) are put in the reservoir, the fish will destroy the ecological balance and the macrophytes which can improve the drinking water quality. Farming fish in net cases with composite food can increase organic pollution to the reservoir. Farming fish in the waters enclosed with the purse seine can also destroy the local macrophyte and ecological balance, and when a great number of the fish are put in the purse seine, the composite food must be thrown into the purse seine in the later culture period. Su farming fish in the purse seine also increases organic pollution by the food to rhe waters. The waste water discharged from the reservoir-side fishponds may increase N, P to the reservoir. The proposals for how to develop the aquaculture and protect the drinking water quality and ecological balance are as follows:1) A great number of grasb carps should not be put blindly in the reservoir; 2) Farming fish in the net case and purse seine should be stopped or limited; 3) The carp (Cyprinus carpio) and crucian carp (Carassius auralus) should be protected; 4) The Xenocyprisargenlea Gunther and Plagionathops microlepis Bleeker) which feed chiefly on decomposed macrophytes should be introduced into the reservoir; 5) Put bigger fiugerlings of silver carp (Hypophth almichthys molitrixi) and bighead carp (Aristuhthys nobilis) to the reservoir, and breed the manderin fish (Sunperaj chuatsi) in the reservoir; 6) The grass carp should be farmed in the reservuir-side fishponds with the macrophytes gathered from the reservoir.