Plankton Abundance Research Articles

Diversity of Stomatocysts of Golden Algae (Chrysophyceae) from the Plankton of Reservoirs of the Mountain Forest Zone of South Urals

According to the data of scanning electron microscopy, in the plankton of the reservoirs, lakes, rivers of the mountain-forest zone of Southern Urals, 33 morphotypes of stomatocysts of Chrysophyceae, 8 of which were found for the first time in Russia, one morphotype was described as new to science. The description of each morphotype is accompanied by a SEM micrography, geographical location, and environmental characteristics. Unornamented stomatocysts with a spherical form are predominant in abundance in plankton. Ornamented stomatocysts with a spherical form are predominant in diversity in plankton. The maximum diversity of stomatocysts is observed in spring and in autumn. The revealed high diversity of stomatocysts indicates a significant diversity of golden algae in the South Ural region.

Exploring phyto- and zooplankton community structure, spatial variation, and driving forces shaping the community from a large-scale freshwater dominated estuary

Abstract Plankton is essential to estuarine food webs, providing key food for species like fish larvae, and understanding their dynamics helps us comprehend ecological interactions and energy transfer in aquatic ecosystems. This study examined the plankton community structure, diversity, variability and the environmental variables of water that influenced these communities in a freshwater-dominated estuary along the Northern Bay of Bengal during the dry season. A variety of tools were employed, including a dissecting microscope, a Sedgwick-Rafter cell, and a Hanna multi-parameter meter, to obtain detailed and comprehensive data. From the analyses, in total 37 genera of phytoplankton belonging to 11 classes such as Bacillariophyceae (66%), Coscinodiscophyceae (28%), Fragilariophyceae (1%), Euglenophyceae (1%), Cyanophyceae (1%), others (3%) were recorded. Zooplankton, consisting of multicellular organisms, was represented by 11 genera across five classes, with Monogononta (53%) and Insecta (29%) being the most prevalent. Phytoplankton exhibited a mean abundance of 180,000 ± 20,200 cells L⁻¹ whereas zooplankton showed a mean abundance of 3,000 ± 200 cells L⁻¹. The diversity indices (H’), evenness (J’) and dominance (D) ranged from 1.188 ± 0.015 to 0.19 ± 0.006, 0.9377 ± 0.002 to 0.5118 ± 0.006, 0.365 ± 0.001 to 0.143 ± 0.002 respectively, suggested low to moderate plankton diversity with a suppressed community and moderate to high dominance in the river water. Based on the similarity percentage (SIMPER) and analysis of similarity (ANOSIM), Phytoplankton and zooplankton varied significantly between stations while non-metric multi-dimensional scaling (nMDS) indicated greater consistency in phytoplankton communities across stations compared to zooplankton. Furthermore, Pearson's correlation coefficient (rs) and canonical correspondence analysis (CCA) identified transparency, sulfates, dissolved oxygen, conductivity, TDS, pH, and salinity as major influencers of plankton abundance; nitrate had a moderate effect. Spearman's rank correlations showed significant positive (p < 0.05) correlations between diversity indices and environmental variables.

Pollution and the abundance of plankton in Rangkui River in Bangka Island

Land use and activity around the Rangkui Watershed affect water quality, and plankton have been studied to help manage the river's water quality. In the 2017 dry season, six station points representing land use functions from upstream to downstream were studied. Surface water sampling was carried out during the day with three replicates. Pollution around the Rangkui Watershed affected plankton abundance. Based on saprobity and physicochemical readings, the pollution level ranged from light upstream to heavy downstream. This study found 15 species from 15 families from six phytoplankton classes, that is, Bacillariophyceae, Chlorophyceae, Euglenophyceae, Cyanophyceae, Cryptophyceae, Dinophyceae, and 2 species of zooplankton Eurotatoria, and Branchiopoda. The highest total abundance of phytoplankton and zooplankton was observed upstream of Station 1 (721 ind/L) and gradually decreased downstream, with the exception of the absence of plankton at Station 3. Nitrate had a positive correlation with phytoplankton at different correlation levels, whereas other abiotic environments responded differently to phytoplankton and zooplankton. The water quality is highest upstream, where there are pepper plantations, and gradually decreases as it flows downstream. The station near tin mining activities was the most polluted.

Cd indirectly affects the structure and function of plankton ecosystems by affecting trophic interactions at environmental concentrations

The toxic effects of potentially toxic elements have been observed at low concentrations; however, many studies have focused on single-species toxicity testing. Consequently, it is imperative to quantify toxicity at the community level at environmental concentrations. A microcosm approach was employed in conjunction with the Lotka-Volterra model to ascertain the impact of environmentally relevant concentrations of cadmium (Cd) on plankton abundance, community function, and stability. The results demonstrated that Cd led to a reduction in the abundance of Daphnia magna, yet unexpectedly resulted in an increase in the abundance of Brachionus calyciflorus and Paramecium caudatum. Additionally, Cd was observed to impede primary productivity, metabolic capacity and the stability of the planktonic community. Further model analyses revealed that the environmental concentration of Cd directly reduced intrinsic growth rates and intraspecific interactions. In particular, we found that the predation effects of Daphnia magna on Brachionus calyciflorus were significantly weakened. The findings of this study offer quantitative evidence that Cd exposure exerts an indirect influence on the structure and functioning of plankton ecosystems, mediated by alterations in trophic interactions. The findings indicate that the impact of environmental concentrations of potentially toxic elements may be underestimated in single-species experiments.

Pengaruh Kualitas Air terhadap Keanekaragaman Plankton di Bozem: Analisis Parameter Fisik, Kimia, dan Biologi Ekosistem Perairan

Water quality plays an important role in maintaining the balance of aquatic ecosystems, including the abundance and diversity of plankton. This study aims to analyze the effect of various water quality parameters such as temperature, dissolved oxygen (DO), carbon dioxide (CO2) levels, Biochemical Oxygen Demand (BOD), pH, brightness, and turbidity on plankton diversity in Bozem. Data were obtained from eight observation stations with water quality parameter measurements and plankton sampling. The results showed that the water quality in Bozem was not optimal, with low DO values ​​(1.79 mg/L), high water temperatures (average 31.05°C), and low brightness (0.30 m), which contributed to the decline in plankton abundance. A total of 39 plankton genera were identified, with Synedra as the most dominant genus. Poor water quality inhibits plankton growth, which can impact the balance of the food chain in these waters. This study shows the importance of better water quality management to maintain the sustainability of aquatic ecosystems in Bozem. This study also contributes to the understanding of the multifactorial interactions between water quality parameters and plankton.

Analysis of Plankton Diversity and Abundance in the Wiringtasi River, Barru Regency, South Sulawesi, Indonesia

The research aims to determine the level of plankton abundance and diversity in the Wiringtasi River, Barru Regency, South Sulawesi, Indonesia. The research was conducted from August to September 2024 at three research locations, namely location 1, namely the river location adjacent to rice fields; location 2, namely the river area adjacent to ponds and beaches; and location 3, namely the location around the mouth of the Wiringtasi River, Barru Regency. Water samples obtained at the research location were taken to the laboratory for analysis. The plankton samples obtained were calculated for abundance, species diversity, species uniformity, and dominance index. The data obtained was then processed and analyzed using descriptive analysis. The results showed that the highest abundance of plankton was in the Melosira sp. type plankton (location 1) and Navicula sp. type plankton (locations 2 and 3). The level of diversity and uniformity of plankton at the research location was highest at location 1, namely the location adjacent to the rice fields. The highest level of plankton dominance is found in the Melosira sp type plankton (location 1), while in locations 2 and 3, the plankton is dominated by the Navicula sp type.

Assessment of plankton diversity and physico-chemical characteristics for sustainable fish production in a tropical reservoir in South India

Plankton forms an important component of the aquatic ecosystem and act as indicators of fish diversity, pollution levels and environmental disturbances. They form an important natural fish food resource and play a vital role in the trophic structure of the ecosystem. In the present study a systematic assessment of the community distribution and diversity of plankton was conducted in the Karapuzha Reservoir in South India. Thirty six genera of phytoplankton belonging to 4 classes viz, Chlorophyceae, Bacillariophyceae, Dinophyceae and Myxophyceae were identified. Eleven genera of zooplankton belonging to four classes; Protozoa, Rotifera, Cladocera and Copepoda were also recorded. The Jaccard index of similarity showed that pre-monsoon and monsoon seasons shared a similar plankton composition. Diversity indices revealed the highest values during monsoon, while the Dominance index indicated the highest species dominance during post-monsoon (0.199) followed by pre-monsoon (0.1445) and monsoon (0.1417). Water quality parameters were found to have a significant correlation with plankton abundance in the reservoir. ShannonWeiner index indicated that the Karapuzha Reservoir ecosystem is moderately polluted. Seasonal variations in plankton composition showed the highest species abundance during the pre-monsoon followed by post-monsoon and monsoon seasons. Keywords: Diversity index, Plankton abundance, Planktivorous fish, Reservoir ecosystem, Seasonal variation

Structure of Plankton and Bentos Communities in Bahorok River in Bahorok District, Langkat Regency, North Sumatra

This study analyzed the diversity and abundance of plankton and benthos in the Bahorok River, Bukit Lawang, Langkat Regency, North Sumatra Province. This study was conducted on May 25, 2024. Sampling was done by collecting filtered water using a plankton net and substrate using a surber net to collect benthos from two points in the river. Identification of plankton and benthos using a microscope and laboratory analysis for physicochemical parameters. The value of plankton diversity in the Bahorok River was indexed well with a value of 3.01 as well as good evenness with a value of 0.95 however, benthos diversity was indexed low with a value of 0.68 and evenness was indexed moderate with a value of 0.62. The highest type of plankton is Raphidiopsis raciborskii. The highest type of benthos is Progomphus sp.

A multidecadal study of the Malabar upwelling system influencing Indian Mackerel landings along the coasts of Karnataka and Kerala, south-east Arabian Sea

Indian Mackerel (Rastrelliger kanagurta) is an essential small pelagic fishery resource, contributing to nearly 30 % of India's total marine fish landing. However, this species' life cycle and stock status are poorly understood and data deficient. Ocean mesoscale events are also known to influence their landing, besides the environmental factors like- salinity, chlorophyll, and sea surface temperature, affecting these small pelagic fishes' availability, migration, feeding, and reproductive activity. The Malabar upwelling region (southwest coast of India) is a significant upwelling system where upwelling occurs during the monsoon months. The nutrient-rich water increases the productivity of surface water, leading to plankton abundance. This productivity sustains a fishery for several commercially important fishes, mainly small pelagics such as sardines, mackerels, and anchovies, supporting India's most significant coastal pelagic fishery. For understanding the relationship between the target fish and the oceanographic events, in the present study, Pearson's correlation has been estimated between Indian Mackerel landing, rainfall, Sea water temperature at 0, 10, 20, 30, 45, and 50 m depths, mixed layer depth (MLD), their anomalies and occurrences of potential fishing zone (PFZ) lines along the Malabar upwelling region and corresponding coasts of Karnataka and Kerala. Mackerel landing time series showed a significant autocorrelation in four-quarter lag, correlation with rainfall anomaly in one-quarter lag, with PFZ line and MLD in three-quarter lag, and with SWT@50 (Seawater temperature@50 m depth) and SST anomaly in two-quarter lag both in Karnataka and Kerala. Upwelling events, as indicated by the presence of PFZ lines, were found to significantly impact the landings of Indian mackerel along the Karnataka and Kerala coasts. Polynomial equations were used to model the relationship between mackerel landings and these environmental factors, effectively capturing the influence of these parameters on mackerel catch trends.

Insight into the diet of early stages of mesopelagic fishes in the Indian Ocean using DNA metabarcoding

Despite playing a critical role in oligotrophic ocean food webs, relatively little is known about the diet of mesopelagic fishes in the Indian Ocean. These fishes are an abundant component of the micronekton assemblages and are a major energy- and nutrient-rich food source, linking the plankton which they feed on to marine predators at higher trophic levels. DNA metabarcoding, a molecular method to identify species from mixed assemblages, has not been commonly used in studies of mesopelagic fish diet, but using it to analyse gut contents can greatly improve the understanding of mesopelagic fish feeding ecology. In this study, we apply DNA metabarcoding (18S rRNA and COI) to gut contents from Stomiiformes and Myctophiformes species from 20 sampling stations covering 30 ˚ of latitude on the 110 ˚ E meridian in the Indian Ocean. In total, 174 fish specimens from 13 genera were examined. Differences in the gut contents among fish families, geographic areas and fish stages were identified. Specimens within the family Myctophidae had the most diverse diet, more so in the northern sampling stations than the south. Gonostomatidae had the least diverse diet. Overall, the most frequently identified prey items from the gut contents were calanoid copepods and halocyprid ostracods. The proportion of halocyprids were also identified to be significantly different among Myctophidae larvae and juvenile specimens, which is a potential ontogenic shift in diet towards a higher ostracod contribution in juveniles as mouth gape increases. In comparison with other plankton abundance data, Copepoda were the most abundant plankton in the gut contents of all fishes sampled throughout the latitudinal gradient, allowing them to be a potential food resource through the region. There are indications that other less abundant plankton, such as like Ostracoda and Malacostraca, may be preferentially targeted by some mesopelagic fish families.

Marine plankton community and net primary production responding to island-trapped waves in a stratified oligotrophic ecosystem

The oligotrophic Adriatic Sea is characterized during a typical summer by low productivity caused by strong water column stratification, which inhibits vertical mixing and nutrient supply to the euphotic zone. These conditions can be disrupted by transient physical forcing, which enhances nutrient fluxes and creates localized hotspots of relatively high net primary production. In this study, plankton abundance and diversity were investigated in relation to the physical forcing and nutrient concentrations in an area affected by island-trapped waves (ITWs) near Lastovo Island (Adriatic Sea). The episodic ITW events resulted in enhanced uplift and vertical excursion of the thermocline, marked by anomalously higher nutrient concentrations and a corresponding increase in net primary production in the thermocline layer. Physicochemical properties explained 11.7 % (p = 0.002) of the variability in micro- and nanophytoplankton and 88.9 % (p = 0.001) in the picoplankton community. A significant response to the ITW phenomenon in the plankton community composition (p = 0.001) was observed for bacterioplankton. Among the identified amplicon sequence variances, primary producers were scarce and mainly represented cyanobacteria (Synechococcus strain CC9902), stramenopiles (Pelagomonas), and chlorophytes (Ostreococcus). The remaining amplicon sequence variances were assigned to the classes Copepoda, parasitic fungi (Meyerozyma spp.), mixotrophic dinoflagellates (family Peridiniales, mostly the genus Blastodinium), and parasitic Ciliophora (Scuticociliata). Bacterial ecological functions corresponded to chemoheterotrophic, degradation, and fermentation processes, whereas samples collected after the most intense ITW episode also showed abundant bacteria linked to microplastic degradation and parasitosis. These results highlight the ecological role of localized physical phenomena in enhancing nearshore primary productivity and fine shifts in plankton taxa in oligotrophic systems.

Influence of different stocking densities of pearlspot (Etroplus suratensis) on plankton diversity indices of biofilm-based rearing system

Aim: Biofilm-based aquaculture systems, proven cost-effective, reduce the need for expensive supplementary feed. The biofilm acts as a natural planktonic food source for reared organisms. Previous research highlighted the influence of fish stocking density and biomass on plankton diversity in different aquaculture settings, underscoring the significance of these factors in biofilm-based systems. Hence, the present study attempted to understand how varying stocking densities of pearlspot (Etroplus suratensis) influence plankton diversity indices in the biofilm-based aquaculture system. Methodology: The present experiment was designed in 5 Practical Salinity Unit (PSU) brackishwater with soil-bottomed FRP circular (500 L) tanks for 60 days. The sugarcane bagasse was used as a substrate forbiofilm production after fertilization with cow dung, urea, and lime. Fries of pearlspot (4.67 ± 0.04 mm 1.71 ± 0.03 g-1) were stocked at four different stocking densities in triplicates viz T1 (50 nos); T2 (100 nos), T3 (150 nos) and T4 (200 nos) fish fry m-3 in the biofilm-based rearing system. Plankton samples were collected from water and biofilm deposited on the substrate and analyzed for diversity indices. The Shannon Diversity Index, Simpson Diversity Index, Simpson Dominance Index, and Margalef Richness Index were used to compute the plankton diversity indices in different treatments using standard equations. Results: In the current investigation, lower stocking densities with lower fish biomass were associated with significantly higher (P≤0.05) Shannon Diversity Index, Simpson Diversity Index, and Margalef Richness Index in water. In contrast, the Simpson Dominance Index in water showed a significantly lower (P≤0.05) value for treatments with lower fish biomass than for treatments with higher biomass. Interpretation: The values obtained for various diversity indices indicated that a biofilm-rearing system with lower E. suratensis biomass produced more planktonic abundance, evenness, and species richness. Key words: Biofilm, Pearlspot, Plankton diversity, Stocking density

High‐Resolution Longitudinal eDNA Metabarcoding and Morphological Tracking of Planktonic Threats to Salmon Aquaculture

ABSTRACTSalmonid aquaculture, a major component of the Northern European, North American, and Chilean coastal economies, is under threat from challenges to gill health, many of which originate from plankton communities. A first step toward mitigating losses is to characterize the biological drivers of poor gill health. Numerous planktonic taxa have been implicated, including toxic and siliceous microalgae, hydrozoans, and scyphozoans; however, rigorous longitudinal surveys of plankton diversity and gill health have been lacking. In the current study, we present and assess an exhaustive identification approach combining both morphological and molecular methods together with robust statistical models to identify the planktonic drivers of proliferative gill disease (PGD) and fish mortality. We undertook longitudinal evaluation at two marine aquaculture facilities on the west coast of Scotland using daily data collected during the 2021 growing season (March–October). Examining these two different sites, one sheltered and one exposed to the open sea, we identified potentially new, important, and unexpected planktonic drivers of PGD and mortality (e.g., doliolids and appendicularians) and confirmed the significance of some established threats (e.g., hydrozoans and diatoms). We also explored delayed or “lagged” effects of plankton abundances on gill health and undertook a comparison of environmental DNA (eDNA) metabarcoding and microscopy in their ability to identify and quantify planktonic species. Our data highlight the diversity of planktonic threats to salmonid aquaculture as well as the importance of using both molecular and morphological approaches to detect these. There is now an urgent need to expand systematic longitudinal molecular and morphological approaches across multiple sites and over multiple years. The resultant catalogue of main biological drivers will enable early warning systems, new treatments, and, ultimately, a sustainable platform for future salmonid aquaculture in the marine environment.

Regime shift in a coastal pelagic ecosystem with increasing human-induced nutrient inputs over decades

Human-induced nutrient inputs to global coastal waters are leading to increasing nutrients and escalating eutrophication. However, how aquatic ecosystem functioning responds to these changes remains insufficiently studied. Here we report the long-term changes in the nutrient regime and planktonic ecosystem functioning in the Daya Bay, a typical subtropical semi-enclosed bay experiencing rapid economic and social development for several decades. Time-series (from 1991 to 2018) data with a mostly quarterly resolution were collected to depict long-term changes in dissolved inorganic nutrients and plankton abundances, based on which we constructed simplified abundance size spectra (SASS) and plankton abundance ratios to describe the functioning of the planktonic ecosystem. The results revealed a long-term increase in system productivity but a decrease in integrated energy transfer efficiency of the planktonic ecosystem, with rising concentrations of dissolved inorganic nitrogen (DIN). Shifts in the nutrient regime and planktonic ecosystem functioning were detected at a tipping point or threshold around 2006–2007. The shifts were characterized by abrupt changes in the trends of nutrient (phosphate, ammonia, nitrite) concentrations, nutrient ratios (DIN/phosphate, silicate/phosphate), plankton abundance, and total plankton biomass. Compared to the nutrient regime, the planktonic ecosystem functioning shifted several years later. Overall, this study indicates that the pelagic ecosystem regime can shift significantly in response to long-term increasing input of human-induced nutrients in coastal waters such as the Daya Bay. The regime shifts may have profound implications for fishery production, and ecosystem management in the bay.

Relationship Between The Dynamics of Plankton Community Abundance, Total Organic Matter, and Salinity in Intensive Shrimp Farming Systems

Plankton plays an important role in shrimp cultivation in ponds, both as an indicator of water quality and as a natural food source for shrimp that are raised. The purpose of this study was to measure the relationship between the dynamics of the plankton community, the concentration of total organic matter, and water salinity with the abundance of plankton in intensive shrimp farming systems. The study was conducted on six units of ponds located in Cirebon district, West Java, Indonesia. The ponds were lined with HDPE on each side and plastic mulch at the bottom. Post larvae of shrimp were stocked at an average density of 110 shrimp.m-2 and maintained for 98 days. Water quality samples were collected for daily measurement. Data were analyzed descriptively and then analyzed using Pearson's correlation test and regression. The results of this study showed that during the shrimp rearing period, 65 species of plankton were identified, consisting of Chlorophyta 20%, Cyanophyta 15.38%, Diatoms 26.15%, Euglenophyta 6.15%, Dinoflagellates 4.62%, Protozoa 10.77%, and Ciliates 16.92% with an average density ranging from 7.56x105-19.99x105 cells.mL-1. Chlorella sp. (Chlorophyta) and Oscillatoria sp. (Cyanophyta) were found to be the dominating species in all ponds. Total phytoplankton density tended to be higher during the first 54 days of culture. The results of the correlation and regression tests showed that the composition of plankton, the concentration of total organic matter, and the salinity of the water affected the abundance of plankton in the pond.

DINAMIKA HARIAN PLANKTON DI TELUK PANGPANG BLOK JATI PAPAK TAMAN NASIOAL ALAS PURWO

National Park Alas purwo is one the conservation areas have a fairly extensive mangrove forest and one of them is the area Bay Pangpang Blok Jati Papak. Mangrove forest have many functions that many marine organisms that occupy the regions one of the region one of which is plankton. Plankton are organisms that are generally relatively small size and its movement depends on the direction of water flow. Plankton are organisms that are generally relatively small size and its movement depends on the direction of water flow. This study aims to determine the abundance and dynamics of plankton daily in at Bay Pangpang Block Jati Papak Nasional Park Alas Purwo. This study was conducted in May-June, 2016. The method used in this research is purposive sampling to determine the point where the (station), and sampling performed every 2 hours over a period of 24 hours. Abiotic parameters include measurements temperature, pH and light penetration. The research found that 13 spec Nitzchia sp, Oedogonium sp, Vaucheria sp, Eretmocaris, Dracia moluska, Amfipod, Micracia, Glaucothoe peroni, Candacia truncata, Candacia curta, Subbeucalamus crassus, Candacia bradi dan Undinula vulgaris. The highest abundanc species of phytoplankton that Nitzchia sp, while the highest abundance of zooplankton that is Candacia truncata species. The highest dynamics of plankton occurs at the time of sampling 07.00 dean in the number of species found are 7 to fotoplankton species and 16 species of zooplankton.

Temporal and Spatial Dynamics of Plankton Communities in the Lower Haora River, Tripura, India

Planktons are significant bioindicator of ecosystem functioning, knowledge of the seasonal fluctuation in the plankton population in riverine waters of Indian subcontinent is rather limited. In the present study, analysis regarding spatio-temporal variations based on different multivariate statistics and indicator value analysis is done along with analysis of community structure of plankton assemblages. A total of 46 plankton taxa out of which 38 phytoplankton and 8 zooplankton taxa have been identified based on examination of samples taken from four locations over three sampling seasons. The primary phytoplankton families that involve Chlorophyceae, Bacillariophyceae, Cyanophyceae, Euglenophyceae and Composopogonophyceae. Chlorophyceae dominated the phytoplankton population, followed by Bacillariophyceae and Cyanophyceae. The plankton abundance was recorded highest in spring, followed by winter, and the least reported in monsoon season. The high average percent contribution of Aulacoseira, Oscillatoria, and Spirogyra species is well represented through SIMPER analysis. In addition, the Shannon–Wiener index (H) was calculated to determine plankton diversity, and Pielous' Evenness index (E) was calculated to determine individual distribution within a community whereas Margalef’s Richness index showed species richness of the study area. This qualitative and quantitative study will aid future research on the occurrence of plankton as well as the more trustworthy information generation on fish diet and feeding behaviors. The condition of planktons as bioindicators would indirectly provide an estimation of the ecosystem's natural state or amount of pollution.

Unprecedented insights into extents of biological responses to physical forcing in an Arctic sub-mesoscale filament by combining high-resolution measurement approaches.

In Fram Strait, we combined underway-sampling using the remote-controlled Automated Filtration System for Marine Microbes (AUTOFIM) with CTD-sampling for eDNA analyses, and with high-resolution optical measurements in an unprecedented approach to determine variability in plankton composition in response to physical forcing in a sub-mesoscale filament. We determined plankton composition and biomass near the surface with a horizontal resolution of ~ 2km, and addressed vertical variability at five selected sites. Inside and near the filament, plankton composition was tightly linked to the hydrological dynamics related to the presence of sea ice. The comprehensive data set indicates that sea-ice melt related stratification near the surface inside the sub-mesoscale filament resulted in increased sequence abundances of sea ice-associated diatoms and zooplankton near the surface. In analogy to the physical data set, the underway eDNA data, complemented with highly sampled phytoplankton pigment data suggest a corridor of 7km along the filament with enhanced photosynthetic biomass and sequence abundances of sea-ice associated plankton. Thus, based on our data we extrapolated an area of 350 km2 in Fram Strait with enhanced plankton abundances, possibly leading to enhanced POC export in an area that is around a magnitude larger than the visible streak of sea-ice.

The role of abiotic and biotic factors within influencing macroinvertebrate communities in a subtropical eutrophic reservoir with thermal stratification

ABSTRACT In this study, we investigated the plankton, water, and macroinvertebrates in Nanwan Reservoir, a subtropical eutrophic reservoir with thermal stratification. We evaluated the status of macroinvertebrate communities and explored the relationships between macroinvertebrate community status and both abiotic and biotic factors. This reservoir exhibited the worst water quality and a high risk of algal blooms in the autumn, whereas it had the best water quality in the spring. The presence of thermal stratification adversely affected macroinvertebrate communities, leading to decreases in species richness, abundance, and diversity. The water characteristics and dominant macroinvertebrate species confirmed that the reservoir was experiencing progressive eutrophication. During the thermal stratification period, the reservoir exhibited a worse status of macroinvertebrate communities, accompanied by an abundance of plankton. The results of PLSR and the Spearman rank test revealed that several abiotic factors, such as water temperature, chlorophyll-a, soluble phosphate, pH, and transparency, as well as biotic factors including the abundance of protozoans, Cyanobacteria, phytoplankton, Bacillariophyta, and Euglenophyta, were the most important factors affecting macroinvertebrate communities. The results of PLS-SEM revealed that both abiotic factors and biotic factors had non-negligible effects on the status of macroinvertebrate communities, with higher effect from abiotic factors compared to biotic factors.

Study of water quality in ex-mining pits for fish cultivation in Gunung Mas regency, Central Kalimantan

Ex-mining pit is a wide expanse, often becomes a problem, especially for the environment. Lack of information about the use of mining pits for fishing activities, especially for the studies on the quality of mining pits to support the growth of cultivated fish. This research was conducted in the village of Tanjung Riu, Gunung Mas Regency, Central Kalimantan Province, using two ex-mining ponds belonging to the community. The results show that the water quality for both mine pits with water parameters for: dissolved oxygen (DO) on average 6.09 mg/l – 7.45 mg/l, pH 2.94 – 3.54, Biological Oxygen Demand (BOD) 4.78 mg/L, temperature 30 -32 oC, turbidity 51.7-53.5 NTU, value of Total Dissolved Solids (TDS) 0.003 – 0.017 gr/L, mercury (Hg) content of 0.000247 mg/l - 0.000359 mg/l, the depth of the pool is 1.7 m – 2.74 m. The abundance of plankton is between 869 - 1106 cells/L, and abundance of benthos is between 264 - 352 ind/m2. The range of pond water quality based on second-class national water quality standards, which is suitable for fish cultivation with moderate abundance of plankton.