Eutrophication Process Research Articles

Assessing trophic state of surface waters of S\u0142u\u017cewiecki Stream (Warsaw)

Phosphorus (P) is one of the key nutrient compounds for phytoplankton grow. In the conducted work, eutrophication indexes were used for the assessment of eutrophication level of water course (Służewiecki Stream) and the waters of nearby lakes (Bottom Berensewicz’s Pond, Wyścigi Pond, Wilanowskie Lake). Calculating eutrophication indexes were based on the most important indicators which is crucial for eutrophication process: total phosphorus (TP), total nitrogen (TN), chlorophyll a (Chl(a)) and water transparency. The research revealed that the concentration of phosphorus and nitrogen in the analysed waters determined intensity of trophic processes. The average concentration of both indicators was high: 0.81 mg/l TP and 6.8 mg/l TN. During this research, two approaches were used: trophic state index (TSI) and trophic level index (TLI). TSI (TP) in Służewiecki Stream were, respectively: 83 and 6.5 whilst for standing waters (lake and ponds) 87 and 6.6. Both indexes indicated high trophic state and confirmed that eutrophication is a serious endangerment for analysed surface waters. Calculated indexes used in the assessment were sufficient and effective for sustainable water protection and management of water quality in Służewiecki Stream and in standing waters.

Coastal eutrophication in China: Trend, sources, and ecological effects

Eutrophication in coastal waters caused by excess nutrient inputs has occurred widely on a global scale. Due to the rapid economic development over the last four decades, most of the Chinese coastal waters have experienced a eutrophic process. Major observed trends of coastal eutrophication include two periods, a slow development from the 1970s to 1990s and a fast development after 2000, with major contributions of increased nitrogen (N) and phosphorus (P) from river inputs, atmospheric deposition, and submarine groundwater discharge (SGD). Nutrient composition and stoichiometry have been significantly changed, including increased ammonium, bioavailable organic N and P, and asymmetric ratios between N, P and silicate (Si). Most of these changes were related to the rapid increases in population density, fertilizer application, sewage discharge, aquaculture and fossil fuel combustion, and have resulted in distinctly increased harmful algal blooms. Coastal eutrophication combined with the effects of climate change is projected to continually grow in coming decades. Targeted research is therefore needed on nitrogen reduction and control, potential adaptation strategies and the consequences for ecosystems and economic sustainability.

СОВРЕМЕННАЯ ГИДРОМОРФОЛОГИЧЕСКАЯ, ГИДРОБИОЛОГИЧЕСКАЯ ХАРАКТЕРИСТИКА И СОСТОЯНИЕ РЫБНОГО НАСЕЛЕНИЯ ОЗЕР ГАЛИЧСКОЕ И ЧУХЛОМСКОЕ КОСТРОМСКОЙ ОБЛАСТИ

Hydrochemical, hydrobiological and ichthyological studies of the two largest lakes in the Kostroma region - Galichskoye and Chukhlomskoye for the period 2005–19 were carried out. Current state of the fish population in comparison with previous periods was analysed. Area of water bodies was updated according to geographic information systems data for 2017–19. The collection and processing of hydrochemical and hydrobiological samples were carried out according to standard methods. The collection of ichthyological materials was carried out by conventional methods using fry drag, small-mesh seines and fixed nets. The boundaries of the lakes were digitized using Landsat satellite images. The hydrochemical indicators of both lakes are within the limits of fishery standards. The hydrochemical regime of Lake Galichskoye is stable. The rise in the water level of Lake Chukhlomskoye had a positive effect on its hydrochemical regime. It has been established that both investigated lakes are currently, as before, highly productive water bodies. According to the concentration of chlorophyll “a” they have a β-eutrophic status, according to quantitative indicators of phytoplankton development they correspond to a high eutrophic level. According to the quantitative indicators of zooplankton, Lake Galichskoye is a low-forage water body (0.37 g/m3), and Chukhlomskoye is a medium-forage water body (2.12 g/m3). Lake Galichskoye is medium-fodder, and Lake Chukhlomskoye is high-forage lakes for benthofagous fish. According to indicator species of zoobenthos, the water of both lakes is classified as an α-mesosaprobic zone, polluted (quality class IV).
 The species richness of fish on Lake Galich – 16 species, on Lake Chukhloma – 12 species, ichthyomass – 221.9 and 176.5 kg/ha, respectively. It was noted that in the reservoirs over the past two decades, serious changes have occurred in the structure of the fish population. In both lakes, perch fish were replaced by cyprinids, which is associated with the process of eutrophication. In Galichskoye Lake, after a sharp decrease in fishing load since 2005, there has been a significant increase in the number of small-sized fish species caused a corresponding increase in stocks of predatory species (pike and pike perch). In the Lake Chukhlomskoye, the ecological niche of the crucian was occupied by the bream, which was acclimatized in the reservoir almost a century ago. It was determined that during the growing season the average area of Lake Galichskoye is 7124.3 ± 57.5 hectares, of Lake Chukhlomskoye – 4862.7 ± 14.7 hectares.

Linking pollution to biodiversity and ecosystem multifunctionality across benthic-pelagic habitats of a large eutrophic lake: A whole-ecosystem perspective

Biodiversity loss is often an important driver of the deterioration of ecosystem functioning in freshwater ecosystems. However, it is far from clear how multiple ecosystem functions (i.e., ecosystem multifunctionality, EMF) relate to biodiversity across the benthic-pelagic habitats of entire ecosystems or how environmental stress such as eutrophication and heavy metals enrichment might regulate the biodiversity-EMF relationships. Here, we explored the biodiversity and EMF across benthic-pelagic habitats of the large eutrophic Lake Taihu in China, and further examined abiotic factors underlying the spatial variations in EMF and its relationships with biodiversity. In our results, EMF consistently showed positive relationships to the biodiversity of multiple taxonomic groups, such as benthic bacteria, bacterioplankton and phytoplankton. Both sediment heavy metals and total phosphorus significantly explained the spatial variations in the EMF, whereas the former were more important than the latter. Further, sediment heavy metals mediated EMF through the diversity of benthic bacteria and bacterioplankton, while nutrients such as phosphorus in both the sediments and overlaying water altered EMF via phytoplankton diversity. This indicates the importance of pollution in regulating the relationships between biodiversity and EMF in freshwater environments. Our findings provide evidence that freshwater biodiversity loss among phytoplankton and bacteria will likely weaken ecosystem functioning. Our results further suggest that abiotic factors such as heavy metals, beyond nutrient enrichment, may provide relatively earlier signals of impaired ecosystem functioning during eutrophication process.

The cultural and political ecology of reed-cane craftsmanship in Lake Eber

The current study examines the interactions of people living around Lake Eber with the lake and their use of it from a cultural and political ecology perspective. In this context, fieldworks were carried out in different periods of 2018-2019. At the same time, observations and interviews covering the research subject were carried out. In the study, it was determined that aquatic plants such as common reed, reedmace, lakeshore bulrush and common cattail are cut from the Lake Eber and are used as building materials and in the production of rush mats, beach umbrellas, prayer rugs, reed pillows, floor mats (straw) and tomb mats. On the other hand, it was observed that the interest in reed-cane craftsmanship and the production of reed-cane products is decreasing every year. This is caused by drought, pollution and eutrophication processes seen in the lake. Based on the results of the study, we suggest that more field studies should be done to examine the factors that threaten the lake ecology and projects should be conducted to improve the situation in the lake.

Anthropogenic stress on a Ramsar site, India: Study towards rapid transformation of the health of aquatic environment

The East Kolkata Wetlands (EKW) region is an important Ramsar Site (huge provisional, regulatory, cultural and spiritual ecosystem services) which is located at the eastern periphery of Kolkata Metropolitan City (India). But in the recent years, illegal land acquisition, wetlands conversion, aquatic species depletion as well as water pollution related diseases have been experienced in different pockets of EKW region. The main objective is to determine regulating factors and stages of eutrophication. The water samples of consecutive three years 2017, 2018 and 2019 (pre and post monsoon) have been obtained from selective 20 wetlands in EKW. The important physicochemical parameters (temperature, electrical conductivity (EC), turbidity, total alkalinity, pH, total hardness, total dissolved solids (TDS), dissolved oxygen (DO), inorganic nitrogen, total phosphorus, potassium, ammonium-nitrogen (NH4+-N), biological oxygen demand (BOD), Secchi disk depth, chlorophyll - a), trophic status index and statistical techniques (like principal component analysis, hierarchical cluster analysis) have been considered to analyze the water quality of these wetlands. The results portray that the magnification of inorganic nitrogen, total phosphorus, potassium and ammonium-nitrogen accelerates the mechanism of eutrophication in the selective wetlands. The DO level has been diminished during 2019 while the BOD level and chlorophyll concentration have been accelerated amidst 2019.The results reveal that about 40% of wetlands i.e. wetland no. 5, 7, 10, 16, 17 (TSI value – 50–70) and wetland no. 8 and 11 (TSI value – 70–100) come under eutrophic and hyper-eutrophic stages respectively due to higher accumulation of nitrogen and phosphorus contents in the wetlands from various non-point sources and these principal components stimulate the processes of eutrophication of the water bodies. Some relevant mitigation measures have been recommended to protect the “kidney of Kolkata Metropolitan City”.

Bacteriome depiction and the trophic status of the largest Northern highland lake from Andes system: Lago de Tota, Boyacá, Colombia.

Lago de Tota is the largest highland lake in Colombia and one of the most remarkable of Northern Andean Mountain range. This lake is under an anthropogenic-based eutrophication process as a consequence of non-sustainable agriculture practices developing nearby. Notable relationship between the trophic status and Bacteriome loop dynamics has been increasingly disclosed in lakes worldwide. We performed a 16S sequencing analysis to depict the bacterial community present and we inferred its potential gene function in Lago de Tota. Parameters for determining current trophic condition such as total nitrogen (TN), dissolved carbon (DOC), particulate organic matter (POM), and chlorophyll-a (chl-a) were measured. A total of 440 Operational Taxonomic Units (OTUs) arranged into 50 classes were identified based on V3-V4 regions of the 16S rRNA gene, harboring high-frequent likely found environmental classes such as Actinobacteria, Gammaproteobacteria, Bacteroidia, Acidimicrobia, and Verrucomicrobiae. A total of 26 bacterial classes configure most abundant predicted functional processes involved in organic matter decomposition (i.e., carbohydrate metabolism, amino acid metabolism, xenobiotic biodegradation, and energy metabolism). In general, Actinobacteria, Alphaproteobacteria, and Gammaproteobacteria show the highest potential gene functional contributors, although other low-frequent classes OTUs are also relevant in processes of carbohydrate metabolism, xenobiotic biodegradation, and energy metabolism. The Trophic State Index indicates an oligo-mesotrophic status, and additional variables measured (i.e., POM, DOC) suggest the increasing carbon accumulation. Results provide preliminary evidence for several bacteria groups related to eutrophication of Lago de Tota. Under this picture, we suggest that further studies for Bacteriome loop spatial-temporal description are essential to inform local water quality monitoring strategies.

Mechanism of eutrophication process during algal decomposition at the water/sediment interface

Water eutrophication has become a global environmental issue recently. Investigating the chemical gradient, spatial heterogeneity of dissolved oxygen, pH, phosphorus, sulfur, and iron (DO–pH–P–S–Fe) at the water/sediment interface during different algal decomposition stages is critical for exploring the underlying mechanism of the eutrophication process. We conducted mesocosm experiments to observe the two-dimensional distribution imaging in micro-interface using a high-resolution system (e.g., diffusive gradients in thin films and planar optode probes). The process of algal decomposition includes three stages: algal accumulation, algal growth, and algal decay. The changes in the dissolved oxygen (DO) observed in overlying water and upper sediments (−15 mm) and the changes in pH occurred throughout the profile, with their peak values (245.14 μmol L−1 and 10.7) corresponding to the highest chlorophyll-a content (600 mg m−3) and maximum photosynthetic activity, respectively. The distribution of P-S-Fe in overlying water and upper sediments (−20 mm) is mainly affected by the changes in DO and pH caused by algal decomposition, whereas it is mainly affected by microbial activities and other chemical processes in deep sediments. P-S-Fe converged from algae cell and sediments to overlying water during algal accumulation, migrated to sediments in algal growth, and stored in algal decay sediments, while formed “black bloom (FeS)” in overlying water. The findings of this study suggest that light and pH should be controlled during algal accumulation for controlling eutrophication. Moreover, P-S-Fe in overlying water and upper sediments is better to remove in this optimal period, which will contribute a new guideline for the environmental sustainability of water eutrophication caused by cyanobacteria bloom.

Case Study Regarding the Variation of the Qualitative Parameters of Wastewater

Romania is making efforts in order to enforce the Directive concerning urban waste water treatment and was left behind by other member states. Starting from the premise that the lack of a proper treatment of wastewater can negatively influence the quality of the emissary in which they are discharged., we proposed that in this paper we analyze the main indicators of wastewater quality, identifying also the causes of water pollution. For this purpose, we followed the variation of five representative indicators of wastewater from Calarasi Wastewater Treatment Plan: chemical oxygen consumption, biochemical oxygen consumption, total nitrogen, total phosphorus, suspended solids. The best results in purification were observed regarding the biochemical oxygen consumption (over 95%). The low temperature of wastewater at the entrance to the Wastewater Treatment Plant during winter leads to a difficult exploitation of the biological step and implicitly to the increase of the phosphorus and total nitrogen concentration in the effluent, which means a weak process of eutrophication in the emissary.

Internal nutrient loading is a potential source of eutrophication in Shenzhen Bay, China

As a highly eutrophic area, Shenzhen Bay in southern China has accumulated plant dissolved inorganic nitrogen (DIN) and phosphate (PO43--P), resulting in various environmental problems. The nutrient loading was calculated to classify runoff patterns of the bay and provide possible management solutions. However, previous studies have shown that external loading alone cannot explain the source of nutrition in Shenzhen Bay. In our study, for the first time, we proved quantitatively that internal nutrient loading was the main contributor of the total input fluxes of dissolved DIN and PO43--P in Shenzhen Bay using the LOICZ (land–ocean interactions in the coastal zone) model. Our results showed that the internal loading supplied 65 and 69% of total input fluxes of dissolved DIN and PO43--P, which were c. 4.0 × 106 and 0.3 × 106 mol/d, respectively. The estimated nutrient input flux from terrigenous loading were c. 1.38 × 106 and 0.1 × 106 mol/d of DIN and PO43--P, respectively. Notably, the internal loading from sediment resuspension supplied c. 3.5–15.7 × 106 and 0.5–1.9 × 106 mol/d of particle nitrogen and bioavailable phosphate to Shenzhen Bay, respectively. Moreover, 51 and 62% of DIN and PO43--P were exported through water exchange and residual flows from Shenzhen Bay into the Pearl River. These results demonstrate that internal loading dynamics and nutrient losses to the Pearl River jointly influence the eutrophication process in Shenzhen Bay.

Tidal action and macroalgal photosynthetic activity prevent coastal acidification in an eutrophic system within a semi-desert region

Nutrient input drive macroalgal blooms and increases in photosynthetic activity in coastal ecosystems. An intense macroalgal photosynthetic activity can increase the surrounding pH and it could prevent the acidification that often follows an eutrophication process. We tested this hypothesis with field sampling and experiments in a macrotidal (up to 9 m in amplitude) coastal system within a semi-desert region with contrasting eutrophic conditions and Ulva lactuca blooms in the northern Argentinean Patagonia (San Antonio Bay). Our results indicate that daily pH variability during low tide could be controlled by the photosynthetic activity of Ulva lactuca under eutrophic conditions. At seasonal scale, the pH variations were related to environmental features, particularly seawater temperature. Both environmental (i.e. high solar radiation, negligible freshwater inputs and large tidal action) and anthropogenic nutrient inputs into the studied area promote the Ulva lactuca blooms, which in turn increases the surrounding pH in well oxygenated seawater through the intense photosynthetic activity. Our study shows that eutrophication instead of being a driver of acidification, could contribute to its prevention in well oxygenated marine coastal systems located within semi-desert regions.

Changes in the Oxygen Regime in the Deep Part of the Black Sea in 1980–2019

Purpose. Assessing changes in the oxygen regime of the deep-water part of the Black Sea under the influence of climatic and anthropogenic factors over the past 40 years is the goal of the work. Methods and Results. For the analysis, the expedition data (2015–2019) and those from the Databank of the Marine Hydrophysical Institute, Russian Academy of Sciences, (1980–2013) were used. The data for the deep-water part of the Black Sea (the depths exceeding 200 m) were selected from the array. The data on hydrophysical and hydrochemical parameters were subjected to expert assessment, and those including random errors in the values were excluded from the array. Then the average profiles of temperature, salinity, oxygen concentration, oxygen saturation, and nitrates concentration were plotted in the density scale (σt). Averaging was carried out by the inverse distance method followed by additional smoothing by the low-frequency filtering method. Conclusions. Against the background of the tendency of temperature increase in the upper layers of the water column and decrease of winter convective mixing intensity, the oxygen supply diminishes in all the layers of the Black Sea aerobic zone. Having been analyzed, of the data for the 1980–2019 period showed that at the present stage, a "regime shift" resulting from the joint effect of climate changes and anthropogenic load took place in the ecosystem of the deep-water part of the Black Sea. Decrease in the oxygen saturation of water throughout the entire thickness of the aerobic zone shows that the process of the Black Sea basin eutrophication constitutes a significant factor affecting oxygen dynamics in the Black Sea waters.

Availability and diffusion kinetic process of phosphorus in the water–sediment interface assessed by the high-resolution DGT technique

Desorption of phosphorus (P) bound to iron-containing minerals (Fe-P) is a crucial component of the eutrophication process in lakes. However, the main process and regulation mechanism of iron (Fe) and sulfur (S) on P release is little known because of a lack of in situ high-resolution data. High-resolution measurement evidence is needed to assess the availability and diffusion kinetic process of P at the water–sediment interface. Soluble reactive phosphate (SRP), ferrous ion (Fe2+), and sulfide (S2−) fluxes through the water–sediment interface in a freshwater lake were detected using the novel double-sided diffusive gradients in thin films (DGT) technique. Different P forms in solid sediment were also measured using the sequential extraction procedure. The diffusion fluxes across the water–sediment interface and dynamic diffusion parameters between solid sediment and solution were calculated using the DGT-induced fluxes in sediments and soils (DIFS) model. There was a clear decrease of the SRPDGT, Fe2+DGT, and S2−DGT fluxes from ~5 cm sediment depth to the water–sediment interface. The significant positive correlation between SRPDGT and Fe2+DGT fluxes in the whole profile demonstrates that Fe-P was a vitally important source of labile P in the solution phase. The significant positive fluxes of SRPDGT and Fe2+DGT indicated upward diffusion from the sediment particle toward the overlying water. This process further indicated the desorption and resupply of SRP and Fe2+ from the solid sediment phase and the synergistic effect between these two parameters. In addition, a gentler decline of R curves fitted with the DIFS model was found as the sediment depths increased, which suggesting the continuous resupply process from solid phase to pore water, especially under anaerobic conditions. The novel DGT technique in combination with DIFS analysis confirmed the considerable remobilization and transport capacity of labile P fractions including loosely adsorbed MgCl2-P and reductive Fe-P. These pools can diffuse from sediment particles to the interstitial and the overlying water, and can be further assimilated by organisms in shallow lacustrine ecosystem.

Structure and dynamics of a Pampa plain, (Argentina) shallow lake over the last 600 years

A multi-proxy analysis, including pollen, non-pollen palynomorphs and plant macrofossil remains was performed to reconstruct the paleoenvironmental history of the Cabeza de Buey shallow lake (36°17′S, 61°10′W) over the last 600 years. We identified the main forcing factors behind changes in the structure and dynamics of the lake communities. Given the relatively low intensity of human activity during the early period of the lake history (prior to 1880 AD), changes in dominant communities were mainly controlled by climate. Afterwards, changes probably resulted from a combination of climate and human impacts that generated an accelerated eutrophication. Four periods in the lake’s evolution were recognized based on changes in macrophyte and algae communities’ structure. Between ca. 1320 and ca. 1630 AD a shift was evidenced from an oligotrophic brackish with low nutrient content (dominated by Botryococcus braunii) to a mesotrophic fresh water body (dominated by Pediastrum and Scenedesmus), due to an increase in the water level associated with an increase in precipitation. At ca. 1840 AD a transition towards a phase dominated by Myriophyllum spicatum was noted, induced by a low water level as a consequence of low precipitation. Later, at ca. 1880 AD, the current lake conditions were established, and the increase in nutrient and organic matter supply influenced plant community structure towards organic tolerant species of submerged macrophytes (Potamogeton pectinatus). Towards the beginning of the twenty-first century, the lake turned to a more eutrophic state, which is evidenced by the dominance of the phytoplankton community. The last hundred years of the lake history were characterized by the eutrophication process related to the impact of agriculture and cattle breeding implemented in the landscape as well as to the urban settlement. This study made it possible to infer changes in the structure and dynamics of Cabeza de Buey lake and to elucidate the forcing factors that induced these changes on a high-resolution scale.

Eutrophication causes invertebrate biodiversity loss and decreases cross-taxon congruence across anthropogenically-disturbed lakes

Eutrophication is a major problem currently impacting many surface water ecosystems. Impacts of increased nutrient concentrations on biodiversity may differ between different scales, different organism groups, and different trophic states. Surveys at different spatial scales have suggested that biodiversity of different taxa may exhibit significant cross-taxon congruence. In our study, we examined the diversity of zooplankton and zoobenthos across 261 lakes in the Lake Taihu watershed, an area that is undergoing a severe eutrophication process. We tested the cross-taxon congruence in species richness and Shannon-Wiener diversity between zooplankton and zoobenthos along a nutrient gradient across the lakes. Our findings were consistent with the intermediate disturbance hypothesis, considering nutrient input as the disturbance. Also, we found significant cross-taxon congruence between zooplankton and zoobenthos diversities. Our results confirmed that excess nutrient levels resulted in diversity loss and community simplification. Zoobenthos were more sensitive to nutrient increases compared with zooplankton, which decreased cross-taxon congruence because these organism groups did not respond similarly to the anthropogenic disturbance.

Prospects for the Assessment of Phytoplankton Biomass in the Black Sea (on the Example of the Karkinitsky Bay) using Earth Remote Sensing

The aim of the study is to assess the dynamics of phytoplankton biomass in the Karkinitsky Bay of the Black Sea, as well as the annual trend of its abundance based on satellite information. The article briefly describes the methodological steps for study the dynamics of phytoplankton biomass from satellite images, indicates the possible reasons for the formation of the eutrophication process in the Karkinitsky Bay, identifies and describes the optical categories of phytoplankton depending on its concentration, the reasons for the seasonal shift in the biomass of phytoplankton in comparison with other parts of the Black Sea by period from 19.02.2019 to 11.04.2020. The study allows to assess the possibilities of using the NDCI index for assessing the biomass of phytoplankton and make the conclusions on the process of eutrophication using the example of the Karkinitsky Bay. The scientific novelty of the work is the use of the NDCI index to study the dynamics of phytoplankton biomass in the Black Sea. As a result, several maxima and minima of phytoplankton biomass accumulation during the year (from 2019 to 2020) were identified and possible reasons for the observed results were described, the main of which can be considered a high anthropogenic load on the studied part of the Black Sea.

Izmeneniye kislorodnogo rezhima glubokovodnoy chasti Chernogo morya za period 1980–2019 gody

Purpose. Assessing changes in the oxygen regime of the deep-water part of the Black Sea under the influence of climatic and anthropogenic factors over the past 40 years is the goal of the work. Methods and Results. For the analysis, the expedition data (2015–2019) and those from the Databank of the Marine Hydrophysical Institute, Russian Academy of Sciences, (1980–2013) were used. The data for the deep-water part of the Black Sea (the depths exceeding 200 m) were selected from the array. The data on hydrophysical and hydrochemical parameters were subjected to expert assessment, and those including random errors in the values were excluded from the array. Then the average profiles of temperature, salinity, oxygen concentration, oxygen saturation, and nitrates concentration were plotted in the density scale (σt). Averaging was carried out by the inverse distance method followed by additional smoothing by the low-frequency filtering method. Conclusions. Against the background of the tendency of temperature increase in the upper layers of the water column and decrease of winter convective mixing intensity, the oxygen supply diminishes in all the layers of the Black Sea aerobic zone. Having been analyzed, the data for the 1980–2019 period showed that at the present stage, a “regime shift” resulting from the joint effect of climate changes and anthropogenic load took place in the ecosystem of the deep-water part of the Black Sea. Decrease in the oxygen saturation of water throughout the entire thickness of the aerobic zone shows that the process of the Black Sea basin eutrophication constitutes a significant factor affecting oxygen dynamics in the Black Sea waters.

Eutrophication in a tropical estuary: Is it good or bad?

Coastal eutrophication is defined as the increase of rate of organic supply into an estuary. In the recent global discussion, eutrophication is seen as a negative situation, in fact, it has positive impacts such as increase in primary production which lead to the increase of fisheries production and hence, community income. This paper promotes a simple diagram called eutrophication-benefit curve which correlates between levels of eutrophication and its benefits to both ecological and economical aspects. In the beginning of eutrophication process, environment gets benefit from the increase of the nutritional state of the water which leads to the increase of primary production and fisheries production. This is obvious in the comparison between northern and southern coast waters of Java Island, showing a higher primary production and phytoplankton biomass and hence fisheries production in the northern coast waters of Java compared to those of the southern coast waters of Java. However, the rapid increase of eutrophication level of the northern coast waters of Java Island causes eutrophication negative effects such as oxygen depletion, algae bloom and disturbance of coral reef ecosystems. This paper shows the optimum level of eutrophication level that can give benefit to both ecological and social environment.

Algae bloom phenomenon in Jakarta Bay as symptoms of severe eutrophication: Monitoring results of 2014-2016

Algae bloom is one of the symptoms of eutrophication process in an estuary, causing in some ecological and societal problems for the aquatic environments and human activities. Algae blooms observation was conducted in the dry season period between 2014 to 2016, in an eutrophic embayment of Jakarta Bay, Indonesia. Observations were made by conducting transect-boat survey and plankton sampling once the bloom was observed. Samples of chlorophyll-a and net plankton were taken and measured in the laboratory for phytoplankton biomass analysis, cell counting, and identification of bloom-forming species. In the 3 consecutive years of observation, the most frequent bloom-forming species observed were Skeletonema costatum, Pseudonitzschia Spp., and Noctiluca scintillans, The most frequent location of the blooms observed was in the inner part of the bay, in the area in front of Marunda, Ancol and Angke. Phytoplankton biomass during the bloom events were ranged between 126.3 to 232.3 μg Chl-a L−1, with the highest was in 2015 of during the Skeletonema costatum bloom. Blooms were also observed but in low frequency and low biomass at the middle part of the bay off Marunda coastline area. Cell phytoplankton counting were ranged from 1.139 ϗ 106 cell L−1 to 7.893 ϗ 106 cell L−1. During period of surveys, there was no mass mortality of fishes were detected.

Quantitative assessment of biogenic elements and suspended matter load to inner-city river: the role of point sources and diffuse runoff

The article provides a quantitative assessment of the input of biogenic elements and suspended matter in the composition of the storm sewer outlets from the territory of the Kazan City (Russia, the Republic of Tatarstan) and the diffuse runoff of biogenic elements from the agro-developed catchments into the Kazanka River (left tributary of the Volga River) as the main risk factors for the development of anthropogenic eutrophication processes. Based on the results of long-term monitoring and the current background concentrations of total phosphorus, nitrogen and suspended solids in the recipient river, determined in the work, the impact of storm water discharge on surface waters within the Kazan City was assessed. The values of permissible loads of phosphorus and nitrogen mineral fertilizers on an agriculturally developed catchment are given for regulating the diffuse runoff of nutrients into a water body, depending on the hydrometeorological conditions of the territory, to a level that meets the basic environmental requirements for the quality of surface waters.