Bay Lake Research Articles

DNA barcoding of common freshwater eleotrids (Gobiiformes: Eleotridae) in the Philippines, with a global comparison and notes on their conservation and management

Eleotrids, also known as gudgeons or sleeper gobies, are found mostly in freshwater and mangrove habitats of tropical and subtropical regions. Some eleotrids exhibit minimal morphological variation at the species level. In this study, DNA barcoding was used to assess the molecular diversity of common freshwater eleotrids in the Philippines in relation to other eleotrid species from other countries with available DNA sequences in public databases. A total of 422 mitochondrial DNA cytochrome c oxidase I (COI) gene sequences were analyzed: 107 of which were generated from this study, while the remaining 315 sequences were mined from Barcode of Life Data System and GenBank. Both the neighbor-joining and maximum likelihood trees constructed based on the COI sequences clustered most of the species in concordance with their taxonomic classification. The mean Kimura 2-parameter genetic distances within species and genera were 1.31% and 11.60%, respectively. As expected, the mean interspecific distance was higher than the mean intraspecific distance except in some species. This study revealed the presence of nine distinct eleotrid species belonging to five genera in the Philippines. These species include Giuris laglaizei, G. tolsoni, Eleotris acanthopomus, E. fusca, E. melanosoma, Belobranchus sp., Belobranchus belobranchus, Butis butis, and Ophiocara ophicephalus. This study also revealed the presence of possibly undescribed Belobranchus species in the Philippines. This undescribed Belobranchus species differs by a high percentage of genetic divergence from the other species of Belobranchus (3.00% from B. segura and 13.40% from B. belobranchus). Furthermore, high genetic distance (2.62%) was also observed between G. laglaizei species of Laguna de Bay and Mindanao. This study strongly recommends a taxonomic review of the Laguna de Bay G. laglaizei and the Philippine Belobranchus spp., as these species may harbor species complexes that require closer examination so that proper conservation and management measures can be implemented for each species.

Antibiotic-resistant Citrobacter spp. from duck eggs in poultry farms and selected tributaries in Laguna de Bay, Philippines: A cross-sectional study

Antibiotic-resistant Citrobacter spp. from duck eggs in poultry farms and selected tributaries in Laguna de Bay, Philippines: A cross-sectional study

Assessment of Physicochemical Parameters in Selected Water Bodies in Laguna, Philippines

This study was aimed to examine the frequent variations in four selected physico-chemical parameters of surface water of two lakes in Laguna: Laguna de Bay in Calamba City and Sampaloc Lake in San Pablo City. Parameters such as conductivity, dissolved oxygen (DO), pH, and temperature were determined using in-situ water quality tester. The two lakes are both freshwater body, different data are collected and observed throughout the sampling. Due to various anthropogenic activities, the lakes are biotically affected. The water quality of the two important lakes in Laguna have been compared in different parameters like pH, DO, conductivity, water temperature and color. The result indicates that both lakes are within the standard (25-31°C) of DENR Administrative Order (DAO 2016-08 for Class C), but except for water temperature which exceeds the standard value (36.37°C mean values). The results support insights about the future effects of increased water temperature on fish management and the lake ecosystem for numerous aquatic purposes. This is also for the management and call on action for the residents and local government unit in said municipalities of Laguna especially after pandemic season.

Life cycle assessment of nutrient recovery strategies from domestic wastewaters to quantify environmental performance and identification of trade-offs

Increase in anthropogenic activities proliferated the consumption of resources such as phosphorus; and increase the adverse environmental impacts especially eutrophication on water resources such as lakes. Nutrient recovery from domestic wastewaters to produce a fertiliser has been explored to address these challenges in the context of a sustainable circular nutrient economy. Life cycle assessment (LCA) was performed to holistically assess the impacts of integrating a nutrient recovery system on wastewater and water resource management using Laguna de Bay, Philippines as the geographical boundary. The inventory was developed based on the results of the emerging nutrient recovery reactor operations and the application of the recovered fertiliser on the agricultural crops. The LCA results for the proposed scenario showed environmental benefits of about 83.6% freshwater eutrophication, 102.5% terrestrial ecotoxicity, 26.9% water consumption, 100.7% mineral resource scarcity, while the global warming potential is 95.4% higher than the baseline scenario. Results imply policy review for septage management, system optimisation, and evaluation of alternative methods of wastewater management, in terms of life cycle thinking and sustainability across the globe.

Genetic diversity and divergence among native and translocated populations of the golden flathead goby Glossogobius aureus (Gobiiformes: Gobiidae) in Philippine lakes

The golden flathead goby Glossogobius aureus is a native species in the Philippines, Australia, Japan, Taiwan, and many other countries in Asia. In the Philippines, it is an important food fish as it is commonly caught in major lakes. In this study, a total of 307 specimens morphologically identified as G. aureus were sampled from nine major lakes in the Philippines and were sequenced for their mitochondrial cytochrome b (cyt b) gene. Two hundred sixty of the 307 cyt b sequences had sequence similarities of ≥ 99% with G. aureus reference sequence in GenBank, while the remaining 47 (all from Lake Lanao) had sequence similarities of only 95% and were thus designated as Glossogobius cf. aureus and treated as a separate population. The sequences were then analyzed to examine the pattern of genetic diversity, relatedness, divergence, and demographic history among native and translocated populations of the species. Twenty-nine haplotypes were recovered, of which four haplotypes were shared among three to seven populations. Only one haplotype each was found in the native population in Lake Buhi and translocated population in Lake Paoay. Low haplotype and low nucleotide diversities were found for the populations in Laguna de Bay, Lanao, Bato, Buhi, Paoay, and Sebu lakes, which indicate founder event for the introduced populations in Lanao, Paoay, and Sebu lakes and recent genetic bottleneck for the native populations in Laguna de Bay, Bato, and Buhi. In contrast, high haplotype but low nucleotide diversities were found for the native populations of Taal, Naujan, and Buluan lakes, signifying a recent bottleneck followed by population expansion. Pairwise FST values showed generally large (FST = 0.168–0.249) to very large (FST = 0.302–1.000) genetic divergence between populations except between Laguna de Bay and Lake Bato, Laguna de Bay and Lake Buhi, and Lake Bato and Lake Buhi populations, which showed nonsignificant genetic differentiation. Lake Buluan and Lake Sebu populations showed moderate genetic differentiation (FST = 0.098). Neutrality tests showed significant negative Tajima’s D and Fu’s FS values only for the population from Laguna de Bay, which suggests that the population is undergoing expansion. These results are important for establishing scientifically sound strategies for effective conservation and sustainable exploitation of G. aureus in the Philippines.

Insights on the connectivity, genetic diversity, and population structure of Arctodiaptomus dorsalis (Marsh, 1907) (Copepoda: Calanoida: Diaptomidae) in the Philippines

Abstract The freshwater calanoid copepod Arctodiaptomus dorsalis (Marsh, 1907) was first recorded from the Philippines in 2001 in Laguna de BayThe copepod gained the status of “invasive species” in 2021 due to its presence in 23 of 32 surveyed Philippine lakes and rivers. Genomic DNA was extracted from 107 individuals of A. dorsalis, representing seven populations on the island of Luzon to gather information on the population structure, genetic connectivity, and range expansion of the species.. A 720-bp fragment of the nuclear ITS1 and ITS2 spacers was used to analyze the genetic structure of the populations. High haplotype diversity (Hd = 0.7951), low nucleotide diversity (π = 0.0024), and low genetic distance between populations indicate high levels of gene flow and low levels of isolation. Six of the 12 haplotypes were unique to particular sites, but the three shared haplotypes suggest panmixia among populations. Tajima’s D (D = 0.4945) and Fu’s F (F = -2.8950) suggest a recent increase in population size following a bottleneck. This may have occurred as the result of the copepod’s suspected initial introduction into the Philippines after 1905 via the trade in ornamental aquarium fish, eventually followed by its expansion into nearby inland waters through one or more aquaculture-mediated introduction events. Laguna de Bay’s role since 1972 as the main source of tilapia fingerlings (Oreochromis niloticus (Linnaeus, 1758)) for release into various Philippine lakes provides circumstantial support for this scenario.

Variabel Daya Tanggap dan Empati Mempengaruhi Kepuasan Pasien Rawat Jalan pada RSUD H. Abdurrahman Sayoeti Kota Jambi

The main problem is also divided into severalsub-problems or exploration questions about service, videlicet 1) What are the service quality variables conforming of power variables? responsiveness, empathy, and patient satisfaction affect sanitarium case satisfaction. H. Abdurrahman Sayoeti Jambi City, and 2) Which service quality variable has the most dominant effect on patient satisfaction at the Sanitarium. The H. Abdurrahman Sayoeti Regional General Hospital, Jambi City, is a Type D General Hospital belonging to the Regional Government of Jambi City. This sanitarium is located at Jl.K.H Hasan AnangNo. 33Rt. 08 Ex. Olak Kemang Kec. Jambi City Bay Lake. Grounded on Mayor RegulationNo. 42 of 2017 the Jambi City Hospital officially uses the name H. Abdurrahman Sayoeti Hospital, Jambi City. This sanitarium was preliminarily the Olak Kemang Inpatient Health Center which in 2018 was converted into a sanitarium. Responsiveness and empathy variables show a tcount value lesser than table (1,663 and 5,329) or sig> a (0.000 <0.05) therefore H0 is rejected and H1 is accepted, meaning that there's a significant positive effect between responsiveness and empathy on patient satisfaction walk in H. Abdurrahman Sayoeti Hospital, Jambi City. The results of this study indicate that the quality of service conforming of responsiveness ( X1) and empathy ( X2) variables has a significant effect on patient satisfaction. Experimenters' suggestions for RSUD. H. Abdurrahman Sayoeti, Jambi City, should be a hospital nurse H. Abdurrahman Sayoeti Jambi City can maximize services according to the promised time, increase trust and responsiveness to patient complaints, maintain empathy and pay attention to the physical installations of the Sanitarium H. Abdurrahman Sayoeti Jambi City.

Growth and Survival of Philippine Endemic Juvenile Silver Therapon (Leiopotherapon plumbeus) Fed with Different Natural Live Feeds

Aquaculture of the endemic silver therapon (Leiopotherapon plumbeus) in Laguna de Bay is now seen as valuable instrument to improve its diminished stock and fisheries. Its dietary preferences during its early life stages are not yet well understood leading to low survival. Hence, the present study examined the effect of different natural live feeds namely, Panagrellus redivivus, Moina macrocopa, Artemia franciscana nauplii, and Paramecium caudatum, on the survival and growth of juvenile silver therapon after 30 days of feeding trials. Panagrellus fed silver therapon juveniles have better survival (97.85%, p<0.05), followed by Artemia (54.37%), Moina (45.26%) and Paramecium (40.67%). For growth, a Panagrellus diet also resulted to significantly higher (p<0.05) mean values for all parameters: weight gain (259.50 mg), length gain (13.40 mm), specific growth rate (5.60%), absolute growth (8.65 mg) and relative growth rate (5.08). Differences in the effects of different live feeds on the survival and growth of L. plumbeus juveniles may be at tributed to their different nutritional composition, with Panagrellus having better total crude protein and fat content, and amino acid and fatty acid composition, which are important in the overall metabolism, growth, development, and survival of fish. The present study demonstrates that provision of Panagrellus to L. plumbeus juveniles will result in significantly better survival and growth.

A new trophic state index for assessing eutrophication of Laguna de Bay, Philippines

A new trophic state index for assessing eutrophication of Laguna de Bay, Philippines

Water Quality Index as a tool for assessing the water quality of the Laguna de Bay from 2020 to 2021

Laguna de Bay (LdB) is a primary freshwater resource that provides multiple ecosystem services. The Laguna Lake Development Authority (LLDA) oversees the periodic monitoring of LdB’s water quality. Data collected by the LLDA can be used to assess LdB’s status using an easily understandable metric. In this study, Water Quality Index (WQI) was used to assess LdB’s quality based on seven parameters (fecal coliform, nitrate, inorganic phosphate, ammonia, biochemical oxygen demand, dissolved oxygen, and pH) measured and recorded by the LLDA from 2020 to 2021. Data from eight major monitoring stations were used to explore how the seven parameters link the stations as well as to compute the WQIs. The lowest WQIs (excellent quality) were obtained using the data representing the end of 2020 for all eight stations, while the highest WQIs (good - poor quality) were obtained for the data measured towards the end of 2021 for Stations I, II, and XVI. Principal Component Analysis (PCA) revealed that the stations had relatively similar environmental influences and overall water quality. Station groupings correspond with the computed WQIs. Stations that had unconventional placements in the biplots (Q3-Q4 of 2021 for Stations I and XVI and Q2 of 2021 for Station V, classified as outliers), correspond to the time points where the lowest water quality was noted. Overall, WQI values are concordant with the water and land use type of the stations. WQI is a useful tool for indicating water quality and is valuable in evaluating LdB and other freshwater resources.

Water Quality Assessment of Santa Cruz River in 2011 and 2022 in the Vicinity of Liliw and Nagcarlan, Laguna, Philippines

Santa Cruz River has significant importance for the economic development of the Philippines and the inhabitants depending on this river for various purposes. It is also one of the 21 major tributary rivers of Laguna de Bay that has a substantial contribution of 15% to the total lake water. This study aims to determine water quality in part of Liliw-Nagcarlan, Laguna of the Santa Cruz River in 2011 and 2022 and to identify the sub-watershed experiencing changes in water quality. There are three sites used for sampling (Talahibing, Bangkuro, and Lapad rivers). Physicochemical and hydrometry were measured in situ. Temperature, pH, and conductivity are within the normal limits. However, dissolved oxygen was generally above the normal limits based on the DENR Water Quality Guidelines. The results showed that the water quality in 2011 and 2022 was projected to change. The number of settlements, recreational activities, and nature park areas increased while the riparian vegetation decreased. The change in land cover will affect the water quality. The result of the assessment for the temperature and conductivity in 2022 was higher compared to 2011. The increase that occurred was influenced by the reduced dissolved oxygen and the pH level, which can cause fish kills and create significant harm to ecosystems. Flowrate was higher from 2022 compared to 2011, since the temperature increased, and the dissolved oxygen levels decreased from this study. Important correlations between the different parameters and the year of the study were proved.

The current ecological and ichthyotoxicological state of the shlis-selburg bay lake Ladoga

The article presents the materials of biological and chemical-analytical studies of the Shlisselburg Bay of Ladoga lake, that plays an important fishery and sanitary-hygienic role as a source of water supply of St. Petersburg. The dominant role of ichthyo-fauna in the assay of the ecological and toxicological state of the studied water area is shown. The purpose of the conducted research is to assess the ecological and ichthyo - toxicological state of the Shlisselburg Bay of Ladoga lake, as one of the main fishery water areal and the only source of water supply of St. Petersburg (the source of the Neva River). Biological and chemical analytical studies of the water area of the Shlisselburg Bay in laboratory conditions were carried out in the summer-autumn period in 2022 in three water areas. A feature of the Shlisselburg Bay is the presence of a runoff flow, that initiates the removal of pollutants and the nature of bottom sediments, which makes the Bay less vulnerable to anthropogenic impact. Currently, the methods used to assess water quality for the fisheries perspective are biological – bioindication and biotesting, as well as the results of chemical analysis in comparison with the standards for the content of harmful substances in water, sediments, precipitation and fish. Preference is given to “express’ methods: biotesting and bioindication of fish research results. Analysis of materials from previous studies have given reason to consider a gradual decrease in anthropogenic load (exposure to pollutants) on fish, as generally recognized indicators of water quality, given from fisheries positions. The results of the research showed that the ecological and toxicological condition of the Shlisselburg Bay has now improved, but cannot be considered satisfactory. Taking into acount the state of the ichthyo fauna and the level of its pollution, it can be characterized as weakly expressed sublethal with a possible transition to medium-expressed, conditionally sublethal in the spring period.

Identification and Characterization of Microplastics on the Surface Water in Laguna de Bay, Philippines

Laguna de Bay is the largest lake in the Philippines. It is surrounded by developing cities that pollute the lake with plastics from different industrial and domestic activities. In the study, microplastics were collected from the lake’s surface water through three (3) collection points within the lake. The collection of microplastics was conducted from August 2018 to October 2018. About eight-hundred ninety (890) microplastics were collected and cataloged. Among the collection sites, ‘Brgy. Sampiruhan’ has the most microplastics, with a median of 15 ranging from 11-24 microplastics per 1000 L of lake water. On the other hand, ‘Brgy. Napindan’ has a median of 4 which ranges from 2-6 microplastics per 1000 L, and ‘Brgy. San Isidro’ has a median of 6 which ranges from 4-24 microplastics per 1000 L. Image analysis revealed that microplastics from this site were larger and angular. The color analysis shows signs of whitening and yellowing of the plastic materials, which suggests that the microplastics undergo photodegradation. Fourier-transform infrared spectroscopy (FTIR) found that most of the microplastics in the lake are made of polyethylene and its derivatives. Microplastics in Laguna de Bay show the continuous plastic pollution in the Philippines’ largest lake.

Microplastics in Northern Laguna Lake’s Shoreline Sediments

Microplastic pollution, a pervasive problem in the natural environment, is hardly investigated in the largest lake in the Philippines: Laguna de Bay or Laguna Lake. This study was done to determine the microplastic profile (content and type) of the shore sediments taken from northern Laguna Lake and to identify possible sources of the microplastics found. The microplastics from the sediments were extracted and isolated using the chemical oxidation and density floatation method. To identify the possible microplastic source, a comparison of Fourier transform infrared (FTIR) spectra of the microplastics extracted with sample plastic materials found on the sites was done. Results showed that during the dry season, the mean microplastic contents of Binangonan, Tanay, and Angono sediments were 1524.42 ± 1593.45, 815.41 ± 593.64, and 295.51 ± 140.16 microplastics per kg sediment, respectively. During the wet season, the mean microplastic contents of the sediments in Binangonan, Tanay, and Angono were 1826.05 ± 614.19, 1250.73 ± 220.03, and 353.82 ± 173.07 microplastics per kg sediment, respectively. The variations observed with season might be associated with tidal and current effects on the shoreline sediments and not due to changes from the dry to the wet season. FTIR analysis of microplastic type showed that prominently occurring microplastics in the three towns varied depending on the materials associated with human activities such as fish farming (aquaculture), clothing materials, and plastic packaging. The results of this study show significant implications on the effect of anthropogenic activities on the type and abundance of microplastics found in the environment, and knowledge of the microplastic profile in Laguna Lake could help not only in its clean-up but also in the proper disposal of plastics in the area to prevent its presence in the natural environment.

Effects of nutrient reduction and habitat heterogeneity on benthic macroinvertebrate assemblages in a large shallow eutrophic lake

The Taihu Lake ecosystem has been subjected to numerous anthropogenic stressors during the past decades, leading to substantial changes in nutrient dynamics and habitat quality. For instance, the northwestern lake bays receive large amounts of nutrient-rich wastewater and have frequently experienced algal blooms, while the eastern lake region is still dominated by submersed macrophytes. Such changes in environmental characteristics can greatly impact benthic macroinvertebrate communities. We used a 15-year monitoring data series collected by the Taihu Laboratory for Lake Ecosystem Research to examine the spatial and temporal variations of the benthic invertebrate fauna and evaluate its status and trends. We found that three major communities could be distinguished based on taxonomic group composition and abundance, and these corresponded well with three lake habitat types: algal-dominated, macrophyte-dominated, and open-lake zone. An analysis of temporal trends showed major changes in the macroinvertebrates during the study period, largely driven by a lake-wide and significant decline in the abundance of pollution-tolerant taxa. The spatial and temporal variations of macroinvertebrate communities were mainly explained by nutrients (e.g., total nitrogen and ammonium concentrations) and habitat factors (e.g., sediment substrates and macrophyte biomass) as indicated by Random Forests regression, but the major drivers of macroinvertebrate density differed among the three lake zones at the temporal scale. Moreover, our findings suggest that benthic invertebrates were more sensitive to the improvement of the lake's environmental conditions than the pelagic community was. This study provides insights into the responses of macroinvertebrates to ecological dynamics in lakes and highlights the importance of continued monitoring for tracking long-term changes.

Temporal and spatial characteristics of key indicators of nutritional level and control standards in Lake Poyang

本文研究2018—2020年鄱阳湖水质及营养水平关键指标——叶绿素a、总磷、总氮浓度时空特征，采用分位值法与压力-响应关系法等研究氮磷基准和适宜的控制标准。结果表明，2018—2020年鄱阳湖水质以Ⅳ类为主，超标污染物为总磷和总氮。近3年鄱阳湖处于“中偏富”营养水平，叶绿素a浓度均值为7.6 μg/L，总磷浓度均值为0.070 mg/L，总氮浓度均值为1.30 mg/L。所有水域在年内皆会出现富营养时段；年内各月份皆有水域处于富营养水平。总磷、总氮浓度枯水期高于丰水期；8月总磷浓度最低，8—9月总氮浓度最低。叶绿素a浓度较高的季节为秋季，尤以9月最高，9月全湖叶绿素a浓度均值和中位值分别为16和12 μg/L，皆超中-富营养界限值10 μg/L，原因在于9月“五河”退水与仍处汛期的长江干流顶托导致流速减缓。叶绿素a浓度较高的水域为入湖河流尾闾水域、浅水湖湾、碟形湖（如南湖村、金溪咀、南矶山、蚌湖等）。鄱阳湖平均N/P比为52，相对于藻类繁殖需求而言，氮、磷皆处于过量状态，总磷宜作为首要控制因子，总氮控制亦应考虑。鄱阳湖总磷基准范围为0.029~0.054 mg/L，总氮基准范围为0.50~0.81 mg/L。考虑当前水污染防治、社会经济发展所处的阶段和现实，目前鄱阳湖适宜的总磷控制标准在0.050~0.100 mg/L之间，适宜的总氮控制标准在1.00~1.50 mg/L之间。另外，对入湖河流控制断面，总磷控制标准应严于目前的0.20 mg/L，并建立适宜的总氮控制标准。;This work studied the key indicators of nutritional level of Lake Poyang in recent three years (2018-2020) including temporal and spatial characteristics of Chl.a, total phosphorus (TP) and total nitrogen (TN). The results showed that the water quality of Lake Poyang was mainly Class Ⅳ, and the pollutants exceeding national standard were TP and TN. The average concentrations of Chl.a, TP and TN during 2018-2020 were 7.6 μg/L, 0.070 mg/L and 1.30 mg/L, respectively. Presently, Lake Poyang is under medium-to-rich nutrient level. All the lake area had eutrophication periods in the year, and in all months of the year, there were regions that were eutrophic. The concentrations of TP and TN in dry seasons were higher than those in wet seasons. TP concentrations were the lowest in August and TN concentrations were lowest during August-September. The season with higher Chl.a concentration was mainly from September to November, especially in September when the mean and median values of Chl.a concentrations were 16 μg/L and 12 μg/L, exceeding the mesotrophic limit value of Chl.a, indicating that the whole lake was eutrophic. The reason was that the velocity of water in the lake slowed down due to the retreat of the Five Rivers in September and the mainstem of the Yangtze River still in the flood season. The waters with high Chl.a were the tail waters of rivers entering the lake, shallow lake bay and dished lake waters, such as Nanhu village, Jinxizui, Nanjishan, Banghu lake, etc. The ratio of nitrogen and phosphorus in Lake Poyang was 52, and both of TN and TP were excessive for algae production. TP should be controlled as a key point, and TN control should also be paid attention too. The reference of TP of Lake Poyang is in the range of 0.029-0.054 mg/L, and TN is in the range of 0.50-0.81 mg/L. Considering requirement of water pollution prevention and social and economic development, it is suggested that TP control objective of Lake Poyang is set in 0.050-0.100 mg/L, and TN in 1.00-1.50 mg/L. In addition, for the control section of rivers entering the lake, TP control objectives should be more strict than current 0.20 mg/L, and an appropriate TN standard should be properly established.

Microplastics in surface water of Laguna de Bay: first documented evidence on the largest lake in the Philippines.

The pollution of aquatic systems by microplastics is a well-known environmental problem. However, limited studies have been conducted in freshwater systems, especially in the Philippines. Here, we determined for the first time the amount of microplastics in the Philippines' largest freshwater lake, the Laguna de Bay. Ten (10) sampling stations on the lake's surface water were sampled using a plankton net. Samples were extracted and analyzed using Fourier-transform infrared spectroscopy (FTIR). A total of 100 microplastics were identified from 10 sites with a mean density of 14.29items/m3. Most microplastics were fibers (57%), while blue-colored microplastics predominated in the sampling areas (53%). There were 11 microplastic polymers identified, predominantly polypropylene (PP), ethylene vinyl acetate copolymer (EVA), and polyethylene terephthalate (PET), which together account for 65% of the total microplastics in the areas. The results show that there is a higher microplastic density in areas with high relative population density, which necessitates implementing proper plastic waste management measures in the communities operating on the lake and in its vicinity to protect the lake's ecosystem services. Furthermore, future research should also focus on the environmental risks posed by these microplastics, especially on the fisheries and aquatic resources.

Lychnothamnus barbatus (Meyen) Leonhardi 1863, A New Species to the Flora of Montenegro

This study presents a newly discovered site of Lychnothamnus barbatus, one of the rarest charophytes worldwide of a disjunctive, Euro-Australasian-American distribution. The species is the only representative of the genus Lychnothamnus on a global scale, hence its threat poses a risk of extinction to the entire lineage. In June 2019, Lychnothamnus barbatus was discovered in Lake Malo Blato, a north-western bay of Lake Shkodra/Skadar, to be a new element to the flora of Montenegro. Lychnothamnus barbatus was recorded at a depth of 3 m, in nutrient-poor but calcium-rich water and on a muddy substrate in the zone of submerged vegetation composed of charophytes and angiosperms. The collected thalli of L. barbatus were young and sterile, green, slightly calcified, and up to 15 cm high. Except for gametangia, all features which are diagnostic for this rare charophyte were well developed. Based on the synthesis of the current state of knowledge, the new site of L. barbatus is presented in the context of the species’ ecological requirements and climatic plasticity, current distribution, and history in the Balkans.

A new method for identifying potential hazardous areas of heavy metal pollution in sediments

The combined effect of pollution source discharge and sediment adsorption leads to the rapid enrichment of heavy metals and other pollutants in lake sediments, which poses a serious threat to the lake ecosystem. Accurately identifying the risk areas of heavy metals in sediments is the key to lake sediment pollution control. Taking Taihu Lake as the study area, combined with the ecological risk status of heavy metals in sediments, the spatial clustering characteristics of pollution sources and the clustering information of sediment attributes, a potential toxic risk area identification method based on sediment source aggregation class (SLISA-SCA) was established. Through the source analysis of heavy metals in sediments, heavy metals such as Cr, Mn, Cu and Zn in Taihu Lake sediments were identified to have originated from natural sources and were subsequently disturbed by human activities to a certain extent. Cd was found to be strongly affected by human activities, and almost all Taihu Lake sediments were affected to varying degrees. In addition, the anthropogenic sources of heavy metals show high concentration clustering characteristics in the lake bay. By K-means cluster analysis of sediment attributes, three significant differences were obtained, which were determined as potential high pollution risk areas, potential medium risk areas and potential low risk areas, and the proportions were 5.6%, 27.6% and 66.8%, respectively. The SLISA-SCA model established in this study, from the perspective of source sinks, comprehensively considers the risks caused by pollution sources and sediment attributes to sediments and divides Taihu Lake into five different risk control areas (high-risk control area, potential high-risk control area, potential risk control area, potential low-risk control area and low-risk control area). This study identified areas with different levels of heavy metal pollution in Taihu Lake sediments, proposes corresponding treatment measures, and provides a scientific and systematic method and technology for the pollution management of other river and lake sediments in the world.

Nitrogen fixation contribution to nitrogen cycling during cyanobacterial blooms in Utah Lake.

Nitrogen (N) cycling is an essential process in lake systems and N-fixation is an important component of it. Recent studies have also found that nitrate reduction through heterotrophic denitrification in lake systems did not prevent harmful cyanobacterial blooms, but instead, may have favored the dominance of N2-fixing cyanobacteria. The overall objective of this study was to estimate nitrogen fixation rates and the expressions of associated nitrogenase (nif gene) functional gene at several sites at different occasions in freshwater Utah Lake. For comparison purposes, one time sampling was also conducted in the brackish Farmington Bay of Great Salt Lake (GSL). The microbial ecology of the top 20-cm of surface water was investigated to assess the dominant cyanobacterial communities and N-related metabolisms. Our study revealed that Dolichospermum and Nodularia were potential N2-fixers for Utah Lake and brackish Farmington Bay, respectively. The in situ N2-fixation rates were 0-0.73nmolN hr-1L-1 for Utah Lake and 0-0.85nmolN hr-1L-1 for Farmington Bay, and these rates positively correlated with the abundance and expressions of the nif gene. In addition, nitrate reduction was measured in sediment (0.002-0.094mgN VSS-1 hr-1). Significantly positive correlations were found among amoA, nirS and nirK abundance (R=0.56-0.87, p<0.05, Spearman) in both lakes. An exception was the lower nirK gene abundance detected at one site in Farmington Bay where high ammonium retentions were also detected. Based on a mass balance approach, we concluded that the amount of inorganic N loss through denitrification still exceeded the N input by N2-fixation, much like in most lakes, rivers, and marine ecosystems. This indicates that N cycling processes such as denitrification mediated by heterotrophic bacteria contributes to N-export from the lakes resulting in N limitations.