Carlson's Trophic State Index Research Articles

Investigating the potential of remote sensing-based machine-learning algorithms to model Secchi-disk depth, total phosphorus, and chlorophyll-a in Lake Urmia

Many terminal lakes in agricultural basins are prone to eutrophication due to restricted inflows and receiving excess nutrients from their basin.The synergy of using satellite data andmachine learning models is a low-cost way to monitor the root-cause water quality variables (WQVs) of eutrophication. This study investigates the potential ofremote sensing-based machine learning algorithms to modelchlorophyll-a(Chl-a), total phosphorus (TP), Secchi disk depth (SD),and Carlson trophic state index (CTSI)in the north part of Lake Urmia (LU).The multiple linear regression (MLR) and artificial neural network (ANN) models were developed using Landsat-8 (L8) and Sentinel-2 (S2) data with nearly concurrent in-situ WQVs of the north part of LU from February 2016 to January 2017. Results showed that models based on L8 were superior to those with S2. Moreover, the ANN models based on L8 for Chl-a, SD, and TP having NSE = 0.75, 0.98, and 0.96, respectively, outperformed MLRs (with NSE = 0.74, 0.81, 0.58). Applying atmospheric correction (i.e., ACOLITE, C2RCC, and C2RCCX) enhances the models.The resultant Chl-aand SD maps indicated an inverse spatiotemporal pattern that agrees with the variation of the abiotic condition in the lake (e.g., surface temperature and total suspended sediments).According to the CTSI maps,the north part of LU was mesotrophic in February and March and eutrophic between June and October 2016. Our study indicates the promising application ofremote sensing-based machine learning algorithms to model the spatiotemporal variation of eutrophication in LU, which provides valuable insights into cost-effective lake monitoring.

The trophic state of the reservoir influences the allometric coefficient and condition factor of Giant Freshwater Prawn (Macrobrachium rosenbergii) cultured in perennial reservoirs of Sri Lanka

Giant Freshwater Prawn (Macrobrachium rosenbergii) is an essential crustacean species in culture-based fisheries of Sri Lanka. Studying the morphometric characteristics and empirical models in fishing and aquaculture is highly beneficial; thus, it is the most accurate way of analyzing growth patterns. The present study aimed to establish the length-weight relationship and compute the relative condition factor for the M. rosenbergii cultured in trophically different perennial reservoirs in Sri Lanka, considering the trophic status of the reservoirs. The allometric coefficient and condition factor of M. rosenbergii concerning the trophic state of the reservoir were empirically ascertained from the samples collected from twenty-five dry-zone perennial reservoirs of Sri Lanka. Carlson's Trophic State Index (TSI) was calculated based on the chlorophyll-a content. The allometric coefficient and relative condition factor were computed using the total length and weight of the M. rosenbergii. The TSI ranging between 44.09±0.47 and 65.15±0.24 differed significantly (p<0.05). Sexual dimorphism in the growth of males over the female M. rosenbergii was ascertained with the aid of allometric coefficient (b value) 3.2306 (positive allometric growth) and 2.9534 (negative allometric growth), respectively. In eutrophic perennial reservoirs, Giant Freshwater Prawns showed the highest allometric coefficient in both sexes. There was a positive correlation between the allometric coefficient and TSI among males, r(23)=0.7210, p<0.001, and combined sexes, r(23)=0.7900, p<0.001, respectively. The results of the present study revealed that the trophic state of the reservoir influences the allometric coefficient and condition factor of M. rosenbergii cultured in perennial reservoirs of Sri Lanka.

Lake Water Quality Assessment Through GIS based Interpolation Method: A Case Study of Beris Dam, Kedah, Malaysia

Preliminary research on physicochemical and water quality in the Beris dam shows that the water catchment area has the best standards and quality during the observation of the wet season and dry season mainly in the northern states of peninsular Malaysia. The analysis of water quality assessment using the DOE-WQI and Carlson Trophic State Index (CTSI) resulted that during the dry season (February), the average DOE-WQI reading is 88 or Class II; while during the wet season, the average DOE-WQI reading recorded 87.1 (October). Although the CTSI score was 34.2 - 27.0 during wet season and dry season, both seasons were classified as oligotrophic conditions. Some physicochemical parameters also show a high correlation between them and indicates minor water quality issues. The use of more efficient interpolation techniques in water quality studies also reinforces the evaluation of water quality. As a reference point for future water research, GIS interpolation application methods can be more effectively and efficiently used with Inverse Distance Weighted (IDW), Ordinary Kriging and Spline techniques. HIGHLIGHTS Investigation of physicochemical and water quality in lake water in Beris Dam Assessment by using water quality index by DOE-WQI and Carlson Trophic State Index (CTSI) to acknowledge water quality and trophic condition. Analyzing physicochemical data into mathematical method to compare between physicochemical data and correlate between them. Application of GIS based interpolation methods to analyze and referencing physicochemical data into spatial interpolation maps. Comparing appropriate spatial interpolation techniques to analyze physicochemical observation data and index. GRAPHICAL ABSTRACT

Water Quality Monitoring for Trophic State of Tasik Kemajuan, Universiti Tun Hussein Onn Malaysia

Aquatic ecosystems offer several ecosystem services, including water purification, nutrient recycling, flood reduction, groundwater recharge, irrigation, and animal habitats. One of the most prevalent challenges freshwater systems face globally is eutrophication. Eutrophication refers to the process of increasing the concentration of plant nutrients in water. The Carlson's Trophic State Index (CTSI) categorises an aquatic environment's eutrophication condition. The parameters exclusively employ three water quality parameters, which are Secchi Disc Transparency (SD), Total Phosphorus (TP), and Chlorophyll-a (Chl-a). Biological indicators refer to living organisms, such as plants and macroinvertebrates, that are implemented to identify and assess the presence of pollutants within a specific ecosystem. Therefore, this study focuses on the determination of trophic state and the assessment of biological indicators of Tasik Kemajuan. Water samples were collected for nine weeks using the composite sampling method for laboratory analysis. Water transparency was determined using a Secchi Disc. The Chl-a was determined by using the determination of chlorophyll-a using 90% methanol and measuring the absorption using a Hach DR6000 UV VIS Spectrophotometer at 663 nm and 750 nm, while the Total Phosphorus was determined by using USEPA1 PhosVer® 3 with Acid Persulfate Digestion Method (Method 8190). Tasik Kemajuan exhibited eutrophic conditions over the duration of the nine-week period. The CTSI values exhibited a range of 60 to 80, thereby demonstrating that the water body under consideration is in a state of eutrophication. The Red Claw Crawfish (Cherax Quadricarinatus), Amona Prawn (Caridina Multidentata), Freshwater Snail (Viviparidae), Tiger Barb (Puntius Tetrazona), and Waterlily (Nymphaeaceae) are among the biological indicators found in Tasik Kemajuan. In conclusion, the analysis of the result shows that the Tasik Kemajuan is in an eutrophic condition, which has high amounts of algae growth, and the bottom waters are seriously depleted in oxygen.

Assessment of wetland landscape changes based on landscape metrics and trophic state index (case study: Anzali International Wetland).

Wetlands play an important role in conserving biodiversity, the hydrosphere's equilibrium, and the maintenance of daily livelihood; therefore, the trophic process hastens the succession procedure in them, resulting in structural changes in the landscape. The study aimed to monitor and investigate the impact of the trophic procedure on landscape structural changes in Anzali Wetland, specifically domains related to vegetation canopy and water bodies, over 24 years. The TSI (trophic state index) of the Anzali Wetland, a vital habitat in the south of the Caspian Sea, was estimated by using the Carlson TSI for 1994, 2002, 2014, and 2018. Based on satellite data for these years, the structural landscape changes were also measured using metrics such as the number of patches (NumP), class area (CA), mean patch size (MPS), and mean shape index (MSI) of the measured patch using in Patch Analyst. The Spearman rank correlation coefficient was then used to calculate the correlation between the two variables of trophic index modifications and landscape metrics. Results showed that the TSI of the wetland touched 59.51 in 1994 and then reached 65.10 in 2018. Its water body area, which was 5283.90 ha in 1994, decreased to 4183.92 ha in 2018, indicating the greatest decrease in the area from 2002 to 2018. In addition, the maximum area of vegetation canopy in 2018 was 11696.31 ha. The trophic exhibited a positive correlation of 0.8 with the area of the vegetation canopy and a positive correlation of 0.4 with the NumP of the vegetation canopy. It also had an inverse correlation of -0.4 with the area and NumP of the water body. Based on the study findings, changes in the trophic level of Anzali Wetland can be regarded as a direct factor influencing the vegetation canopy and water body.

Evaluation of the water quality of a high Andean lake using different quantitative approaches

This study assessed a high Andean lake's trophic state and water quality using methodologies with eutrophication and water quality indexes. Water samples were collected at six points in the lake, with a monthly frequency, for three winter and three summer months. Dissolved oxygen, pH, phosphates, nitrates, transparency, chlorophyll-a, fecal coliforms, biological oxygen demand (BOD), temperature, and turbidity were determined at each point. The trophic state of the lake was categorized by applying the Organization for Economic Cooperation and Development (OECD) eutrophication index, Carlson's trophic state index (CTSI) and trophic index (TRIX). In addition, National Sanitation Foundation water quality index (NSF-WQI), Canadian Water Quality Index (CCME-WQI) and Oregon Water Quality Index (OWQI) were used to evaluate water quality. Results indicated that the lake had a high level of eutrophication, suggesting an excessive accumulation of nutrients in the water. CTSI and TRIX index showed that the lake was in a hyper-eutrophic state, while according to the OECD methodology, the trophic state related to phosphorus and transparency was hypereutrophic, and according to chlorophyll, it varied from mesotrophic to eutrophic. The NSF index classified the lake with average quality, the CCME index indicated fair water quality, and the OWQI classified it as very poor. Therefore, the water quality of the high andean lake assessed by eutrophication and water quality indexes presented significant differences based on physicochemical characteristics. The human influence was identified as the main cause of eutrophication, including tourism and agriculture. These results suggest that measures should be taken to reduce human activity in the area and control pollution in the lake.

Utilizing Satellite Imagery for Seasonal Trophic Analysis in the Freshwater Reservoir

Eutrophication, an aquatic problem that impacts water quality and ecosystems, can be addressed through technological developments utilizing satellite imagery to analyze the trophic status of water. This study aimed to determine the trophic status of the freshwater reservoir in different seasons using satellite imagery. Water quality data were obtained from field surveys (11 samples) during the wet and dry seasons in Cirata Reservoir (Indonesia) while the remote sensing images were obtained from the Landsat-8 OLI. Trophic status refers to Carlson's Trophic State Index consisting of two parameters named chlorophyll-A and water transparency. This study found that satellite imagery could estimate seasonal trophic information. During the wet season, the algorithms determined information about chlorophyll-A (48%) and transparency (35%). Whereas during the dry season, the algorithms successfully estimated both information at 59% and 21%, respectively. Unfortunately, the Landsat-8 OLI had limitations for estimating total phosphorus. From these two parameters, the trophic status in the Cirata Reservoir showed moderate (wet season) and mild (dry season) eutrophic. Cirata Reservoir has a higher trophic level during the wet season since it has more surface water supply with lots of pollutants.

Determination of Quality and Trophic Status of Cibabat Lake, Cimahi City

In Cimahi City, the river water is heavily polluted, and well water is not suitable for drinking water, so to anticipate the lack of clean water, the Environmental Service is planning to revitalize one of the ponds, namely the Cibabat Lake. This study’s purpose is to determine the reservoir’s condition based on water quality and trophic status. The method used for calculating water quality status is the Pollutant Index, which refers to the Decree of the Minister of Environment Number 115 of 2003 with results is 8,450, and will be 8,751 in 2022, with the water quality classified status as moderately polluted. Meanwhile, the method to assess trophic status uses the Carlson Trophic State Index (TSI) method by taking air samples for the parameters Total Nitrogen, Total Phosphate, Chlorophyll-a, and brightness which is included in the hypereutrophic category. The Cibabat Reservoir has been polluted by domestic waste based on the calculation of the potential pollutant load such as BOD, COD, TSS, Total Phosphate and Total Nitrogen in the border area is 2,219,600; 3,051,950; 2,108,620; 11,623; and 108,206 kg/day, respectively. DTA area is 1,886.660: 2,594.158; 1,792.327; 9,905; 91.975 kg/day, respectively. This is influenced by the increasing population each year.

Influence of hydrological state on trophic state in dam induced seasonally inundated flood plain wetland

A Good many research works focused on investigating wetland habitat state and trophic state (TS) but as far the knowledge is concerned, very little attention was paid to the hydrological state (HS) modelling of wetlands, and no such attention was paid on exploring the linkage between HS and TS. But it is very essential to explore the role of hydrological characters on TS in order to frame hydrological management strategies. Considering this, the present study intended to build HS models using image-driven hydrological components like water presence frequency, hydro-period, water depth; to estimate trophic state index (TSI) using field-driven water samples and, finally linking HS and TSI of the wetland. Successful results can open up a new approach to improve the strategies for water quality and ecological efficiency management. Machine learning models were applied for building the HS model and Carlson's TSI method was applied to explore water quality and ecological state. The ordinary least square regression was applied for linking HS and TSI. Results showed that hydrological modification and associated causes obliterated 32.32 km2 of wetland between the pre-dam and post-dam periods. The support vector machine model was found as the best-suited HS model to all the applied models. TSI was found poor over a wider part of the wetland, especially over the hydrologically poor patches of the wetland. The hydrological worsening is a cause for the worsening of TS. So, it can be stated that managing hydrological components is a good way to manage TS.

Eutrophic Status Assessment Based on Very High-Resolution Satellite Imagery in the Coastline Environment of Korea

Anthropoid activities are severely altering natural land cover and growing the transport of soil, organic and inorganic compounds, nutrients, toxic chemicals, and other pollutants to the water ecosystem. The eutrophication of the coastal water environment is one of the furthermost bitter consequences of human activities. In this research, we have used three different satellite images for efficient land-use land-cover (LULC) classification, comparison, and further coastal water quality assessment over the coastal zone of the Boseong County of South Korea. The results of LULC classification showed that Landsat-8, Sentinel-2, and WorldView-3 gave an overall accuracy of about 74%, 82%, and 96% with Kappa coefficient of 0.71, 0.78, and 0.91, respectively. By comparing, LULC accuracies and kappa coefficient, the very high-resolution Worldview-3 satellite imagery is considered one of the best-suited satellite imageries for water quality assessment. The study used recently developed algorithms for the calculation of the transparency of Secchi depth, concentration of Chlorophyll-a, Total Phosphorus, and Total Nitrogen; whereas the eutrophication status of the coastal water has been identified using the Carlson Trophic State Index (CTSI) method. The result show that the medium state of eutrophication occurred nearby agricultural regions and urban settlements. Overall, trophic status of the coastal water is ranged from 61.56 to 74.37 with a mean value of 65.63 (CTSI) and placed under the medium eutrophic state. The study analysed that the nutrient entrance from the surrounding land cover is high and needs proper water treatment before releasing into a coastal ecosystem. Hence, these investigations will assist the various local and international agencies in improving the reliability of the monitoring of eutrophication state, dynamics, and potential impacts.

AWWA Water Science Author Spotlight

<i>AWWA Water Science</i> Author Spotlight

Influence of net cages on water quality and trophic status of Lake Victoria, Kenya: The case of Kadimu Bay

AbstractWater quality is a critical component regulating ecosystem functioning in aquatic habitats, requiring regular monitoring for sustainable ecosystem services. Cage fish farming has the potential to affect water quality because of its rapid increase in many African waterbodies in response to dwindling wild fish stocks. Thus, there is a need for more studies to guide sustainable cage aquaculture in African lakes and reservoirs. This study evaluated the possible effects of cage farming of Nile tilapia (Oreochromis niloticus) on water quality parameters and the trophic state of Kadimu Bay, Lake Victoria, Kenya. Sampling for physicochemical and biological variables, including nutrient load, was conducted from January to October 2021, at five fish cage sites and a control site within the bay. In situ measurements of physical variables were undertaken in the field, while analysis of water samples for nutrient loads, biological and chemical variables was undertaken in the laboratory, following the methods described in APHA (American public health association standard methods for the examination of water and waste water. APHA‐AWWA‐WEF, 2005). The Carlson's Trophic State Index (CTSI) was used to classify the trophic state of the cage sites, while the total nitrogen:total phosphorus (TN:TP) ratio was used to determine the primary productivity limiting nutrient in the bay. The study results indicated electrical conductivity was significantly lower at the control (97.53 ± 4.17 μS/cm), compared to cage sites (105.42 ± 5.32 μS/cm at the Utonga cage site to 112.84 ± 1.94 μS/cm at the Oele cage site), indicating water of relatively lower quality at the cage sites. Similarly, the nitrite concentrations were higher at cage sites (6.35 ± .96 μg/L at the Uwaria cage site to 3.16 ± 2.25 μg/L at the Utonga cage site), and lower at the control site (2.68 ± 1.39 μg/L). In all, 14 physicochemical variables did not vary significantly between the cage and control sites, with nine variables (temperature, turbidity, electrical conductivity, total suspended solids, particulate organic matter, chlorophyll‐a, TP, nitrate and TN) being within the recommended thresholds for aquatic life processes. The bay was evaluated as being in a light eutrophic state, indicating moderate influence of the fish cages on the trophic state of the sites. There was a moderate relationship between chlorophyll‐a and TP concentration at the sampling sites (R2 = .50), compared to a stronger relationship with (R2 = .78). The TN:TP ratios were &lt;10 at the sampling sites, indicating nitrogen was the limiting factor for primary production in the bay. The calculated CTSI suggests that the bay exhibited a light eutrophic state. Overall, although the results of this study showed cage aquaculture is not a current challenge to the water quality of the bay, regular monitoring is nevertheless recommended to inform sustainable aquaculture development in the bay and lake.

Carlson's Trophic State Index for the Assessment of Trophic state of Phewa, Begnas and Rupa Lakes in Kaski district, Nepal

Eutrophication of wetlands has been considered as a global level environmental problem due to wide range of environmental impacts caused by it. All the lake bodies are subjected to natural eutrophication process but anthropogenic activities like excessive utilization of inorganic fertilizers containing phosphorus and nitrogen in the farmlands which ultimately reach to water bodies through runoff during rainfall further maximizes the eutrophication. The research was conducted to find the trophic state of Lake Phewa, Lake Begnas and Lake Rupa which are three major lakes of Lake Clusters of Pokhara Valley, a Ramsar listed wetland from mid-hills of Nepal. Trophic state of lakes were classified on the basis of Carlson’s Trophic State Index. This index was calculated with the measurement of Secchi depth, Chlorophyll-a, and Total Phosphorus using standard methods. Study revealed that all three lakes were mesotrophic in both pre-monsoon and monsoon season. Lake Rupa had the highest Carlson Trophic State Index (CTSI) and Lake Begnas had lowest CTSI in both the season. Development of lake from oligotrophic to eutrophic state is a natural and gradual process and hence these lakes have increased chances of being eutrophic naturally along with natural process being crucially altered by cultural eutrophication which shortens the life expectancy of the affected aquatic body. Suitable conservation measures are needed to reduce organic load from lake to prevent from being further degraded.

Prediction of Carlson Trophic State Index of Small Inland Water from UAV-Based Multispectral Image Modeling

This paper demonstrates a predictive method for the spatially explicit and periodic in situ monitoring of surface water quality in a small lake using an unmanned aerial vehicle (UAV), equipped with a multi-spectrometer. According to the reflectance of different substances in different spectral bands, multiple regression analyses are used to determine the models that comprise the most relevant band combinations from the multispectral images for the eutrophication assessment of lake water. The relevant eutrophication parameters, such as chlorophyll a, total phosphorus, transparency and dissolved oxygen, are, thus, evaluated and expressed by these regression models. Our experiments find that the predicted eutrophication parameters from the corresponding regression models may generally exhibit good linear results with the coefficients of determination (R2) ranging from 0.7339 to 0.9406. In addition, the result of Carlson trophic state index (CTSI), determined by the on-site water quality sampling data, is found to be rather consistent with the predicted results using the regression model data proposed in this research. The maximal error in CTSI accuracy is as low as 1.4% and the root mean square error (RMSE) is only 0.6624, which reveals the great potential of low-altitude drones equipped with multispectrometers in real-time monitoring and evaluation of the trophic status of a surface water body in an ecosystem.

Combination of Acoustic Telemetry and Side‐Scan Sonar Advances Suppression Efforts for Invasive Lake Trout in a Submontane Lake

AbstractExpansion of an invasive Lake Trout Salvelinus namaycush population in Swan Lake, Montana, threatens a core area population of Bull Trout S. confluentus. Given the recent development of novel suppression methods, such as use of carcass analog pellets to cause high mortality of embryos, there was a need to quantify spawning season aggregation sites, site use, and spawning habitat for Lake Trout in Swan Lake. Acoustic tags were implanted in 85 Lake Trout during the summer in 2018 and 2019. Nightly tracking efforts during autumn in both years resulted in 1,744 relocations for 49 individual Lake Trout. Kernel density analysis was used to evaluate Lake Trout aggregation sites, identifying 10 distinct sites. All spawning sites were located in the littoral zone along areas of steep bathymetric relief, and these sites composed 48% of total relocations during both spawning seasons. In 2019, side‐scan sonar imaging was used to classify and quantify the total area of spawning substrate, which constituted 12.8% of the total surface area estimated for spawning sites 1, 6, and 9 and 11.4% of the total surface area for aggregation sites 2–5, 7, 8, and 10. Simultaneous treatment of all spawning sites would require 205,709 ± 86 kg of carcass analog pellet material, resulting in 370.4 ± 0.2 kg of phosphorus inputs and 7,487.9 ± 3.1 kg of nitrogen inputs to Swan Lake. Thus, pellet treatment would increase the Carlson's trophic state index (TSI) values from 20.8 to 27.7 for total phosphorus and from 22.1 to 26.2 for total nitrogen. Based on a TSI threshold of less than 40 for an oligotrophic lake, the use of carcass analog pellets could be feasible for supplementing the gill‐netting suppression of Lake Trout in Swan Lake.

The Determination of Trophic Level of Küçükçekmece Lagoon Lake (İstanbul, Türkiye) by Using Some Environmental Variables with Indicator Benthic Macroinvertebrates Findings

In this study, to determine the trophic level of Küçükçekmece Lagoon Lake, water and sediment samplings were performed at five selected stations seasonally during a year between 2014-2015. The water samples were analyzed to determine some environmental variables (water temperature, pH, conductivity, DO (dissolved oxygen), TDS (total dissolved solids), and salinity. NO3-N, NO2-N, SO4-2, PO4-3, SiO2, chlorophyll-a, TP (total phosphorus), and Secchi disc light permeability) and benthic macroinvertebrates were examined to determine indicator organisms in the sampled sediment material. Bray-Curtis Similarity Index was used to the observed environmental results to determine the similarities of the sampling stations. According to this, station 1 (St. 1) located in the center of the lake, and St. 5 located near the sea were found to be different from other sampling stations while the stations located near the creeks were found to have much more similar to each other. In addition, to determine the trophy level of the lake, Carlson Trophic State Index (CTSI) was used to the obtained some physicochemical results (Secchi disc permeability, total phosphorus, chlorophyll-a) and it was found that the lake showed a eutrophic character during all seasons. According to the result of sediment sampling, an average of 350 individuals per m2 (44.3 % belonging Polychaeta group; 29.5 % belonging Chironomidae group; 19.7 % belonging Oligochaeta group; 6.5 % belonging Bivalvia group) in a total of 6 benthic macroinvertebrate taxa (Bivalvia, Polychaeta, Tubificoides benedii (Oligochaeta), Tubificoides sp. (immature Oligochaeta), Limnodrilus hoffmeisteri (Oligochaeta), and Chironomus salinarius (Chironomidae) were determined. Thus, it is observed that the presence of some indicator species supported eutrophic conditions qualitatively. As a result of this study, it was determined that Küçükçekmece Lagoon lake going on to expose the increasing pollution load.

Spatial and temporal variations of trophic state conditions of Lake Bunyonyi, south-western Uganda

The study was conducted to assess the spatial and temporal variations of the trophic state condition of Lake Bunyonyi between October 2019 and September 2020. Secchi depth (SD), total phosphorus (TP) and chlorophyll-a (Chl-a) concentration were measured to aid the quantification of trophic state condition of the lake using Carlson trophic state index (CTSI). The trophic state index (TSI) values based on SD, TP and Chl-a values were 60.82 ± 5.35, 68.99 ± 11.04 and 61.74 ± 7.51, respectively. March 2020 recorded the highest mean CSTI value (70.14 ± 4.04), while in September 2020, the lowest mean value (58.03 ± 6.22) was obtained. Based on CTSI values, the lake was eutrophic in both dry and wet seasons albeit with differences in the values. The eutrophic state of the lake is possibly attributed to nutrients inflow into the lake via runoff and drainage from farmlands. The negative value of TSI-Chl-a–TSI-TP deviation pointed out that the lake is not phosphorus limited, while the positive TSI-Chl-a–TSI-SD mean deviation value revealed the effect of Chl-a and TP on the lake’s transparency. The study recommends the necessity to develop guidelines for the trophic status monitoring of Lake Bunyonyi since results suggest the deteriorating lake condition.

Using Multiple Indices for the Water Resource Management of a Monomictic Man-Made Dam in Southern Africa

This study employed different indices, namely the weighted arithmetic water quality index (WQI), Carlson Trophic State Index (TSI), van Ginkel TSI, and Trophic Level Index (TLI) to determine the water quality status of a man-made dam for the needs of sustainable water resource management in Southern Africa. The selection of indices for the study was based on the impacts of anthropogenic activities on the dam. The Roodeplaat Dam exhibited the spatial variation of physicochemical characteristics, indicative of influence by point-source pollution. Although the dam was classified as being eutro-hypertrophic, it was evident that water clarity was not a limiting factor but was P-limited, which was an indication of limiting conditions on primary production. Moreover, the WQI calculated for the dam with an average of 93.94 demonstrated very poor water quality that could be used for crop irrigation purposes only. As such, continued nutrient enrichment must be mitigated to sustain fitness for irrigation, at least. However, strategic goals should involve widening fitness for use. The selected indices were found to be effective for water resource management and could be applied to dams impacted by point-source pollution in Southern Africa. Thus, this study recommends the implementation of an integrated management approach, which needs to prioritize nutrient management to retain societal resource value.

Bacterial community composition and indicators of water quality in Caizi Lake, a typical Yangtze-connected freshwater lake.

Caizi Lake is an important lake connected to the Yangtze River in Anhui Province and a crucial connection for the Yangtze-to-Huaihe Water Diversion Project. There were marked differences in trophic status of the six sampling sites based on the physicochemical characterization. The Bacterial Eutrophic Index (BEI), used to quantify water quality, was well related to Carlson's trophic state index (TSI) (Spearman's ρ = 0.829, P<0.05). Mean TSI and BEI were 54 and 0.58, respectively, indicating that Caizi Lake was slightly eutrophic. Actinobacteriota were the predominant bacterial phylum in the water and Acidobacteriota in sediments. The diversity and composition of the bacterial community was markedly different between sites for water but not sediment samples. Unlike other Yangtze-connected freshwater lakes, the distance-based redundancy analysis revealed that dissolved oxygen affected the composition of the planktonic bacterial community (P<0.001), while total phosphorus was the major factor in the sediments (P<0.05). The water quality of Caizi Lake has significantly improved since a few years ago. These results contribute to the long-term monitoring of the ecological quality of the water environment along the Yangtze River to the Huaihe River.

STATUS TROFIK PERAIRAN SITU KEBANTENAN, KABUPATEN BOGOR, PROVINSI JAWA BARAT

Activities at Situ Kebantenan contribute to the entry of various types of waste. These wastes include domestic waste, fishery and industrial waste. The water supply of Situ Kebantenan comes from the Cisadane River and Ciliwung Riverwhich indirectly carries garbage. If the condition of the entry of the pollution load occurs continuously, it will certainly have a bad impact on the quality of the waters and the organisms that live in the waters of Situ Kebantenan. The level of fertility in the in situ waters can minimize and control the pollution load that enters from the surrounding environment so that the existence of the in situ ecosystem can be utilized sustainably. Therefore, it is necessary to do research on the level of fertility of the waters using the TRIX (Trophic Index) calculation formula. The purpose of this study was to determine the trophic status of Situ Kebantenan, Bogor Regency, West Java Province based on the TSI (Carlson Trophic State Index) method and the TRIX (Trophic Index) method.This research was conducted in April-May 2019. Sampling of water and in-situ parameter testing was carried out at Situ Kebantenan located in Cibinong, Bogor Regency. Ex situ tests included TN (Total Nitrogen), TP (Total Phosphate) and chlorophyll-α. In the research procedure, samples were taken 3 times with an interval of 14 days and on the surface of the Situ Kebantenan waters. The method used in this study included measurements of chlorophyll-a levels, total phosphate and total nitrogen. Based on the Carlson Trophic Index (TSI) method on testing water samples in the waters of Situ Kebantenan, it shows that the TSI value is included in the eutrophic category with values ranging from 112.12-125.53. Based on the Trophic Index (TRIX) method, the Kebantenan Situ has a TRIX value ranging from 2.034 to 2.78 which is included in the mesotrophic category.