High Phytoplankton Abundance Research Articles

Struktur Komunitas Fitoplankton dan Tingkat Pencemaran di Danau Dendam Tak Sudah, Kota Bengkulu

Dendam Tak Sudah Lake (DDTS) is an aquatic ecosystem and nature reserve located in Dusun Besar Village, Singgaran Pati District, Bengkulu City. Its presence serves not only as a tourist destination and irrigation water supply for rice fields but also as a habitat for phytoplankton. The land use changes around the DDTS Nature Reserve have impacted the water quality of the lake, and phytoplankton are among the biota affected by these pressures. This study aims to assess the phytoplankton community structure and the pollution level in DDTS. The research was conducted by identifying and counting each phytoplankton species found and analyzing water quality. The results of the study showed that the phytoplankton richness in DDTS consisted of 20 species, including 8 species from the Bacillariophyceae class, 6 species from the Chlorophyceae class, 2 species from the Cyanophyceae class, and 4 species from the Euglenophyceae class. The highest phytoplankton abundance was found at the inlet with 1,135.2 individuals/l, followed by the midlet with 1,095.6 individuals/l, and the outlet with 997.2 individuals/l. The diversity index values were high (2.6-2.8), the evenness index was high (0.95-0.96), and dominance was low (0.07-0.08). The saprobic coefficient in DDTS was classified as β-Meso/Oligosaprobic, indicating that the water quality is lightly polluted, with a saprobic index value ranging from 0.6 to 0.87.

Phytoplankton Community and Physico-chemical Parameters Influence on the Seasonal Visits of Lesser Flamingos (Phoeniconaias minor) in Chelekleka Wetland, Central Ethiopia

Background and Research Aims Lesser flamingo ( Phoeniconaias minor) is an intra-African migratory bird species recorded mainly in alkaline lakes of the Great Rift Valley. Temporal patterns of Lesser flamingo visits may be related to the abundance and availability of their primary phytoplankton food items, and phytoplankton growth and composition may also be influenced by water quality parameters. This study aims to investigate the relationship between Lesser flamingo abundance and the physico-chemical characteristics of the wetland and its phytoplankton community dynamics. Methods We measured the abundance of Lesser flamingos using the ground vantage point counting method. We assessed water physico-chemical characteristics using field measurements of temperature, dissolved oxygen, pH, electrical conductivity and turbidity, and laboratory sample analyses for phosphorus, ammonia, nitrate, silica, alkalinity and chlorophyll a. We also measured phytoplankton diversity and abundance in the laboratory. Results The physico-chemical characteristics of the Chelekleka wetland showed a favorable environment for biological productivity and physiological activities of aquatic organisms. High phytoplankton richness (83 taxa) and abundance were recorded in the wetland. Lesser flamingo abundance varied significantly in response to the abundance of preferred phytoplankton prey items, which could be attributed to the effect of aquatic grazers and changes in the physico-chemical characteristics of the wetland. Conclusion Water physico-chemical characteristics influence the abundance and availability of phytoplankton in the seasonally flooded wetland, which in turn influences the seasonal visitation and abundance of Lesser flamingos foraging on phytoplankton prey. Implications for Conservation We recommend that the local government and other relevant stakeholders implement integrated wetland conservation practices to alleviate wetland degradation and conserve the ecosystem and its associated wildlife.

ABUNDANCE INDEX AND COMMUNITY STRUCTURE OF PHYTOPLANKTON IN THE INTEGRATED MARINE AQUACULTURE AREA OF EKAS BAY, WEST NUSA TENGGARA

The development of Ekas Bay as a center for integrated aquaculture activities, particularly through the Floating Net Cage (FNC) system, can impact phytoplankton abundance and water fertility. Phytoplankton, a type of plankton capable of photosynthesis, acts as a primary producer and serves as a key food source for fish and lobsters. The presence of phytoplankton is closely related to the fertility levels of waters designated for marine aquaculture. This study aims to determine the composition and abundance of phytoplankton in the waters of Ekas Bay. The research employed purposive sampling, collecting phytoplankton samples from five predetermined stations: three points near FNCs and two points distant from the FNC area. The results indicate that the plankton abundance in the waters of Ekas Bay is categorized as mesotrophic. The highest phytoplankton abundance was recorded at Station V with 9,523 cells/L, while the lowest was at Station II with 2,150 cells/L. Based on station characteristics, Station V is the farthest point from FNCs, whereas Station II contains a high concentration of FNCs. The community structure, as indicated by the H’, E, and D values, suggests that the waters of Ekas Bay remain in a stable condition. Phytoplankton from the class Bacillariophyta was the most commonly found, although no specific genus was dominant.

Plankton Community Structure in the Estuaries of Banten Bay, Banten Province, Indonesia

Estuaries in Banten Bay support fisheries activities by serving as critical habitats for plankton communities, which form the foundation of the aquatic food web. This study aims to determine the structure of plankton communities, both phytoplankton and zooplankton, as baseline data for fisheries management in Banten Bay estuaries. Fieldwork was conducted in April and October 2021 at four estuaries in Banten Province: Karangantu, Wadas, Cengkok Estuary, and Pamong. Water samples were collected for plankton identification and analysis of physical and chemical water quality parameters in situ and laboratory. Key structural attributes, including Shannon - Wiener diversity index (H'), evenness index (E), dominance index (C), trophic status and canonical correspondence analysis (CCA), were also assessed. The highest abundance of phytoplankton was found in the Karangantu estuary, while the highest abundance of zooplankton was observed in the Pamong estuary, with overall abundance higher in April. Phytoplankton diversity was highest in Karangantu in October, whereas zooplankton diversity peaked in April. Plankton diversity indicated slight to moderate pollution levels, and trophic status analysis revealed eutrophic to hypertrophic conditions across the estuaries, suggesting high nutrient levels that support fish productivity. CCA revealed significant correlations between environmental variables and plankton composition and abundance. Mitigation strategies are recommended to monitor the growth of Chaetoceros sp. and Bacteriastrum sp., especially during the dry season. Long-term monitoring of water quality and plankton dynamics is essential in other estuaries of Banten Bay to assess nutrient loading impacts and develop strategies to mitigate harmful algal blooms. These efforts are critical to ensuring sustainable fisheries management in the region.

Community Structure, Abundance and Ecological Index of Phytoplankton in Jembrana Coastal Waters, Bali

Phytoplankton is an important component in aquatic ecosystems. Apart from producing oxygen, phytoplankton also act as primary producers in the food chain. Bali Sardinella (Lemuru) is an important fishery commodity in the Bali Strait, which is known to eat plankton (Plankton Feeder), so its existence depends on the distribution of plankton. This descriptive research aims to determine the community structure, abundance and ecological index of phytoplankton in the coastal waters of Jembrana Regency. Sampling was conducted in July 2023 at five observation stations in the coastal waters of Jembrana Regency (Pengambengan Beach, Perancak Beach and Delod Berawah Beach). Around 250 litres of seawater was filtered by a plankton net measuring 35 mm. The filtered samples collected in a 100 ml collecting bottle were then transferred to a 120 ml sample bottle and preserved in 4% formalin. The samples obtained were taken to the laboratory for observation under a microscope. This research shows that 66 types of phytoplankton were found to belong to 5 classes in the waters of Jembrana, Bali. The Bacillariophyceae class were found with the highest number of species (44 species), followed by the Dinophyceae (19 species), Chlorophyceae (1 species), Cryptophyceae (1 species), and Cyanophyceae (1 species). Based on the results of calculating phytoplankton abundance, various abundance values ​​were obtained at each observation station. Station 2 has the highest abundance of phytoplankton with 297 individuals/l followed by Station 1 (221 individuals/l), Station 4 (130 individuals/l), Station 3 (127 individuals/l), and Station 5 (36 individuals/l). The species Diversity Index (H') ranges from 2.61 - 2.83, the Dominance Index (C) ranges from 0.07 - 0.13, and the Evenness Index (e) ranges from 0.72 - 0.95. The ecological index value shows that the phytoplankton community in Jembrana coastal waters included in the moderate diversity category is not dominant and evenly distributed. The ecological index value shows that the water quality is categorized as moderately polluted.

Phytoplankton Structure in a Coastal Region of the Eastern Entrance of the Gulf of California during La Niña 2022

This paper assessed the phytoplankton structure and its relationship with the physical environment in the coastal region off Mazatlán, Mexico, in two seasons of 2022, a year in which a strong La Niña event took place: (1) the warmer (August) and (2) the transitional period to the cold phase (November), based on hydrographic data and samples collected in two systematic scientific expeditions. The results showed clear differences between both seasons. Regarding total abundance, August reached 125,200 cells L−1, while November amounted to 219,900 cells L−1. Regarding species composition, the diatoms Cylindrotheca closterium and Planktoniella sol were dominant in August, while Thalassionema nitzschioides and Tetramphora decussata dominated the assemblages in November. The dinoflagellate Protoperidinium punctulatum was dominant in both seasons. However, very marked differences in its abundance are reported. The differences observed in the species richness and abundance could be attributed to the physical configuration of the water column, particularly the surface temperature, which showed clear changes between both seasons. The results presented here confirmed the high phytoplankton richness (some of them with the potential to generate harmful algal blooms), abundance, and diversity values of the region, suggesting a strong relationship with the physical environment.

QPCR-based phytoplankton abundance and chlorophyll a: A multi-year study in twelve large freshwater rivers across the United States

Phytoplankton overgrowth, which characterizes the eutrophication or trophic status of surface water bodies, threatens ecosystems and public health. Quantitative polymerase chain reaction (qPCR) is promising for assessing the abundance and community composition of phytoplankton. However, applications of qPCR to indicate eutrophication and trophic status, especially in lotic systems, have yet to be comprehensively evaluated. For the first time, this study correlates qPCR-based phytoplankton abundance with chlorophyll a (the most widely used indicator of eutrophication and trophic status) in multiple freshwater rivers. From early summer to late fall in 2017, 2018, and 2019, we evaluated phytoplankton, chlorophyll a, pheophytin a, and the Trophic Level Index (TLI) in twelve large freshwater rivers in three regions (western, midcontinent, and eastern) in the United States. qPCR-based phytoplankton abundance had positive allometric correlations with chlorophyll a concentration (adjusted R2 = 0.5437, p-value < 0.001), pheophytin a concentration (adjusted R2 = 0.3378, p-value <0.001), and TLI (adjusted R2 = 0.4789, p-value < 0.001). Thus, a greater phytoplankton abundance suggests a higher trophic status. This work also presents the numerical values of qPCR-based phytoplankton abundance defining the boundaries among trophic statuses (e.g., oligotrophic, mesotrophic, and eutrophic) of freshwater rivers. The sampling sites in the midcontinent rivers were more eutrophic because they had significantly higher chlorophyll a concentrations, pheophytin a concentrations, and TLI values than the sites in the western and eastern rivers. The higher phytoplankton abundance at the midcontinent sites confirmed their higher trophic status. By linking qPCR-based phytoplankton abundance to chlorophyll a, this study demonstrates that qPCR is a promising avenue to investigate the population dynamics of phytoplankton and the trophic status (or eutrophication) of freshwater rivers.

The utility of simulated ocean chlorophyll observations: a case study with the Chlorophyll Observation Simulator Package (version 1) in CESMv2.2

Abstract. For several decades, a suite of satellite sensors has enabled us to study the global spatiotemporal distribution of phytoplankton through remote sensing of chlorophyll. However, the satellite record has extensive missing data, partially due to cloud cover; regions characterized by the highest phytoplankton abundance are also some of the cloudiest. To quantify potential sampling biases due to missing data, we developed a satellite simulator for ocean chlorophyll in the Community Earth System Model (CESM) that mimics what a satellite would detect if it were present in the model-generated world. Our Chlorophyll Observation Simulator Package (ChlOSP) generates synthetic chlorophyll observations at model runtime. ChlOSP accounts for missing data – due to low light, sea ice, and cloud cover – and it can implement swath sampling. Here, we introduce this new tool and present a preliminary study focusing on long timescales. Results from a 50-year pre-industrial control simulation of CESM–ChlOSP suggest that missing data impact the apparent mean state and variability of chlorophyll. The simulated observations exhibit a nearly −20 % difference in global mean chlorophyll compared with the standard model output, which is the same order of magnitude as the projected change in chlorophyll by the end of the century. Additionally, missing data impact the apparent seasonal cycle of chlorophyll in subpolar regions. We highlight four potential future applications of ChlOSP: (1) refined model tuning; (2) evaluating chlorophyll-based net primary productivity (NPP) algorithms; (3) revised time to emergence of anthropogenic chlorophyll trends; and (4) a test bed for the assessment of gap-filling approaches for missing satellite chlorophyll data.

Diel variation of plankton in the highly impacted freshwater zone of Hooghly estuary in relation to ecological alteration.

Plankton are promising ecological monitoring tool that responds quickly to any sort of aquatic ecological alteration, of which many of them are much susceptible to ecological variations. Therefore, monitoring shifts in plankton composition can indicate changes in water quality and aid to identify potential pollution sources. In the present study, the variation in plankton dynamics in relation to ecological variables were monitored in the freshwater zone of the Hooghly estuary from May 2020 to April 2021. The study was conducted in the interval of every six hours. i.e., at 6 A.M., 12 P.M., 6 P.M., and 12 A.M. The present finding revealed the occurrence of 54 phytoplankton and 20 zooplankton taxa/species. Diel variation revealed that among different time intervals, the highest abundance of phytoplankton was recorded 28,307 cells l-1 at 12 P.M, while the lowest was recorded 10,632 cells l-1 at 6 A.M. However, the highest zooplankton abundance was observed 804 ind l-1 at 6 A.M., and the lowest was recorded 156 ind l-1 at 6 P.M. The ANOVA (p < 0.05) analysis indicated significant diel variation for many planktonic genera. The CCA exhibited that most of the phytoplankton were influenced by multiple water quality variables such as temperature, turbidity, calcium, pH, salinity, DO, and nutrients. However, the majority of the zooplankton were affected by turbidity, total phosphorus, sulphate, calcium and available nitrogen. Significant seasonal variation in plankton composition has also been observed. The present study will help to determine the varying diel pattern of planktons in retort to alterations in the water quality parameters and varying ecological niches.

The study of phytoplankton in the Banggai Deep Sea: The study case of Banggai Upwelling Dynamics and Ecosystem Experiment (BUDEE)

The upwelling process in the Banggai deep-sea water occurs yearly during the east monsoon. The upwelling process is characterized by low surface water temperatures compared to the surrounding waters, high nutrient values of phosphate, nitrate, and silicate, and high values of primary productivity. The aim of this research was to determine the types of phytoplankton that are abundant in the Banggai deep-sea waters during the upwelling process. Phytoplankton sampling was conducted at 36 stations using a phytoplankton net from a depth of 150 m to the water surface. The mesh size of the phytoplankton net was 80 µm with a net length of 100 cm. Phytoplankton samples were preserved using 4% formalin. Based on the research results, the highest total abundance of phytoplankton was found at station 13 (315.457 cells.m-3), followed by stations 20 (234.746 cells.m-3), 26 (213.865 cells.m-3), station 14 (202.371 cells.m-3), station 18 (196.983 cells.m-3) and station 46 (187397 cells.m-3). Meanwhile, the other stations had an abundance of &lt;150,000 cells/m3. The highest abundance at station 13 was dominated by the genera Bellerochea (64.068 cells.m-3), Chaetoceros (42.407 cells.m-3) and Nitzschia (35.390 cells.m-3). The high abundance of phytoplankton at Station 13 was due to upwelling.

Evaluation of phytoplankton abundance and wastewater quality in intensive vannamei shrimp ponds in the northern coastal area of Bangka Island

Abstract Effluent waste generated from the intensive production of vannamei shrimp is known to play an essential role in increasing phytoplankton abundance and the alteration of environmental quality. This alteration is characterized by the presence of various organic compounds and their derivatives. The northern coastal area of Bangka Island represents a region in Indonesia that has witnessed significant growth and development as a vannamei shrimp cultivation zone. Therefore, this study aims to evaluate phytoplankton abundance and environmental quality in the waste of shrimp ponds in the northern coastal area of Bangka Island. The investigation procedures were carried out in four specific locations within this area, namely BL1, BL2, BL3, and BL4. The results showed the presence of five–six distinct phytoplankton groups, including a total of 11–18 genera, within the effluent discharge from these ponds. The highest abundance of phytoplankton was recorded at BL3, with a value of 2,418,375 cells ml−1. The phytoplankton groups identified at all locations included Chlorophyta, Cyanophyta, Chryptophyta, Bacillariophyta, and Pyrrophyta. Euglenophyta was found at BL1 and BL3 but was not observed at BL2 and BL4. Furthermore, the most abundant group found in this study was Chlorophyta. The genera Nanochloropsis, Chlorella, Microcystis, and Nitzschia were consistently found in all the surveyed ponds. The calculation results showed that all locations had a moderate level of diversity, high evenness, and the absence of dominance. Based on the findings of principal component analysis, there was a commonality in parameters that exerted a strong influence on phytoplankton abundance, including nitrate, orthophosphate, and magnesium.

Application of organic fertilizer made from solid waste from shrimp ponds for tilapia nursery (Oreochromis niloticus)

The solid waste of super-intensive aquaculture ponds can be used as organic fertilizer. Organic fertilizers are useful in soil nutrient enrichment and improvement. The purpose of this study was to utilize the solid waste of super-intensive ponds as an organic fertilizer for the nursery of tilapia (Oreochromis niloticus). The treatments applied were: (A) organic fertilizer of solid waste of shrimp ponds with a dose of 0.1 kg/m2, (B) organic fertilizer of solid waste of shrimp ponds with a dose of 0.2 kg/m2, (C) organic fertilizer of solid waste of shrimp ponds with a dose of 0.3 kg/m2, (D) without organic fertilizer (control). The parameters observed were the growth of natural feed (plankton), tilapia’s growth and survival rate, and water quality. The growth and survival rate data were analyzed using oneway ANOVA, while water quality and natural feed data were analyzed descriptively. The result showed that the absolute growth of tilapia obtained during the study ranged from 0.1955-0.3158 g/ind with SGR 0.6517-1.0527%/day. The highest phytoplankton abundance in treatment A was 102858 ind/L, and zooplankton was 70354 ind/L. The study’s water quality supported tilapia’s growth and natural feed.

Plankton dynamics and physico-chemical parameters: A longitudinal investigation in carp and catfish culture ponds

An experiment was aimed to discover the overall scenario of physico-chemical parameters along with the qualitative and quantitative analysis of plankton in two different fish culture systems as carp mixed culture and catfish (Pangus) monoculture from September 2021 to February 2022 using conventional techniques. The mean values of transparency and dissolved oxygen (DO) noted at the catfish culture pond were lower than those at the mixed carp culture pond while pH mean values were observed to be higher in the catfish culture pond than in the mixed carp culture pond. A total of 21 genera of phytoplankton were found in both ponds under the groups of euglenophyceae (4), cyanophyceae (4), bacillariophyceae (5) and chlorophyceae (8). Among zooplankton, 13 genera were identified including Rotifera (7), copepoda (2), cladocera (3) and crustacean larvae (1) were recorded in mixed culture ponds whereas in catfish culture ponds, 11 zooplankton genera were recorded including Rotifera (5), copepoda (2), cladocera (3) and crustacean larvae (1). Planktonic abundances were statistically significantly different between the different levels (phytoplankton abundance in CCP, phytoplankton abundance in MCP, zooplankton abundance in CCP, zooplankton abundance in MCP), χ2(3) = 220.46, p &lt; 0.001. Mixed culture pond cyanophyceae, bacillariophyceae, and euglenophyceae are positively associated with water temperature and pH but negatively correlated with DO. Rotifera is negatively associated with catfish culture pond water temperature, whereas chlorophyceae and cyanophyceae are favorably. Catfish monoculture ponds had higher phytoplankton abundance, so phytoplankton grazing fish species could be included with pangus culture to maintain a better water quality.

Daily Fluctuation of Planktons Abundance in Percut Sei Tuan Waters, Deli Serdang Regency, North Sumatera

Plankton is an aquatic biota that lives following the currents in the water. The life of plankton is highly dependent on the water quality in those aquatic environments. The constantly changing physical and chemical conditions of water lead to fluctuations in the abundance of plankton in a water. This study aims to analyze fluctuations in plankton abundance and its correlation with water quality in Percut Sei Tuan Waters. The study was conducted in February and March 2023. Filtration method at 3 stations is the Sampling technique used in this study. The sampling period is carried out in the morning, afternoon, and evening. Data analysis to determine the relationship between variables using Pearson correlation in SPSS version 26. Based on the research results, 42 genera of phytoplankton and 16 genera of zooplankton were found. The highest abundance of phytoplankton was 4.635 Ind/L during the afternoon. The highest abundance of zooplankton was obtained at evening, which was 1.049 Ind/L. This is due to the daily vertical migration of zooplankton and their negative phototactic behavior, while phytoplankton require light for photosynthesis. The research results indicate that the abundance of phytoplankton has a very strong correlation with temperature, light intensity, salinity, TSS, pH, DO, and Nitrate. The abundance of zooplankton is highly correlated with water flow velocity, light intensity, salinity, TSS, TDS, pH, DO, Nitrate, and Phosphate.

Speciation, distribution and relationship of zinc and cadmium in summer coastal seawater of northern China

Considering that zinc (Zn) is essential for marine phytoplankton growth and cadmium (Cd) can replace Zn as a cofactor of mutual conversion and regulate the effect of carbonic anhydrase, we here presented the concentration, chemical speciation and relationship of Zn and Cd collected from three consecutive voyages (2019–2021) in summer coastal seawater of northern China. Dissolved Zn and Cd concentrations were determined using inductively coupled plasma mass–spectrometry (ICP–MS) and ranged from 0.37 to 3.09 μM and 1.88–13.66 nM, respectively. Natural labile Zn and Cd were determined using a highly automated electrochemical detection system and ranged from below detection limit-1.11 μM and below detection limit-5.23 nM, respectively. The speciation, distribution and interrelationships of Zn and Cd were compared with the distribution of the diatoms community, and studied by the correlation with pH and dissolved inorganic carbon (DIC). Finally, the Zn and Cd labile and inert chemical species concentrations were compared with those of the open sea and the coast. The results indicated that the dissolved Zn and Cd concentrations in surface seawater were higher than those in bottom seawater, possibly due to the dominance of exogenous inputs compared to phytoplankton uptake. Higher phytoplankton abundance was associated with lower natural labile Zn and Cd concentrations, but this was not the main factor affecting the distribution of natural labile Zn and Cd. Unlike the open ocean, there was no potential for Zn limitation of certain phytoplankton groups in this region, but both Zn and Cd played important roles in the fixation of carbon dioxide, and Cd might result in mitigating Zn uptake. Activities such as ocean currents, which bring limiting nutrient trace metals (e.g., Zn) from the coast into the open ocean, could regulate the structure of primary producers. This study has great potential for the investigation of the biogeochemical cycling of Zn and Cd and their role in marine carbon fixation in coastal seawater.

KEANEKARAGAMAN PLANKTON DAN HUBUNGANNYA DENGAN KUALITAS AIR SUNGAI SEKITAR PABRIK KELAPA SAWIT (STUDI KASUS DI ASAM-ASAM, JORONG KABUPATEN TANAH LAUT)

The Asam-Asam River is one of the waters located in Tanah Laut Regency and is in an oil palm plantation area which is very close to the Palm Oil Mill (PKS). The Asam-Asam River has an important role for the surrounding community who use these waters as a source of water for the community around fishing activities, domestic activities such as washing clothes and supplying water for oil palm plantations. Water from PKS activities is thought to have changed the condition of the waters of the Asam-Asam river, therefore identification of plankton diversity in the Asam-Asam River was carried out and data collection of water quality parameters (pH, temperature, DO, BOD, COD, Nitrate and Phosphate) as supporting data for the identification results plankton. This research was conducted in August 2021. Observation points and water sampling were carried out at 2 stations in the Asam-Asam River. The supporting parameters observed were pH, temperature, DO, BOD, COD, nitrate and phosphate. Station II had the highest abundance of phytoplankton because the presence of the genera Oscillatoria, Tablelaria and Spirogyra was much higher than Station I. In the results of the two observation stations, the class Bacillariophyceae was the most common.

Subsurface phytoplankton responses to ocean eddies can run counter to satellite-based inference from surface properties in subtropical gyres

Phytoplankton contribute approximately half of the Earth’s primary production, playing a crucial role in marine ecosystem functioning and global carbon cycling. However, our understanding of how ocean dynamics regulate the distribution of phytoplankton remains limited due to the scarcity of depth-resolved observations. Here, we compared the simultaneous measurements of two biogeochemical-Argo floats that tracked a cyclonic eddy (CE) and an anticyclonic eddy (AE) in the subtropical South Indian Ocean for a period of 3 months. The observations revealed a decoupling of subsurface phytoplankton biomass from surface chlorophyll. The CE exhibited a subsurface phytoplankton bloom initiated by the springtime shoaling of mixed layer to euphotic layer, accompanied by a counter-intuitive decrease in surface chlorophyll due to physiological adaptation. In comparison, the AE exhibited vertically homogeneous phytoplankton biomass, with a weak subsurface chlorophyll maximum layer, as the mixed layer remained at a deep level in the spring. Despite a higher concentration of surface chlorophyll in the AE than in the CE, subsurface and depth-integrated phytoplankton chlorophyll, biomass, and productivity computed with a bio-optical model are greater in the CE than in the AE. Statistics on global biogeochemical-Argo measurements over the past decade confirm the generality of this phenomenon in subtropical gyres. Our findings demonstrate that high concentrations of chlorophyll near the surface in these regions are not necessary indicative of high phytoplankton abundance at the subsurface layer. The results have important implications for inferring subsurface phytoplankton abundance and productivity from satellite measurements.

Community structure of plankton in Whiteleg Shrimp, Litopenaeus vannamei (Boone, 1931), pond ecosystem

Abstract. Inayah ZN, Musa M, Arfiati D, Pratiwi RK. 2023. Community structure of plankton in Whiteleg Shrimp, Litopenaeus vannamei (Boone, 1931), pond ecosystem. Biodiversitas 24: 4008-4016. Plankton in shrimp farming can be used to maintain the balance of the pond ecosystem. The purpose of this study is to analyze the plankton community in the whiteleg Litopenaeus vannamei shrimp pond ecosystem. This research was conducted in January-April 2023 and it is a descriptive study using a survey method. The research location is in an intensive whiteleg shrimp aquaculture pond in Probolinggo, East Java. The results showed that the plankton found in whiteleg shrimp ponds consisted of phytoplankton and zooplankton. The phytoplankton found consisted of 4 phyla with 18 genera, while zooplankton consisted of 3 phyla with 8 genera. Phytoplankton phylum consists of Bacillariophyta, Chlorophyta, Cyanophyta and Dinophyta, while zooplankton consists of Arthropoda, Ciliophora and Rotifera phyla. The highest total abundance of phytoplankton was 8,192,370 cells/L, while zooplankton was 55,121 cells/L. The highest abundance of phytoplankton was Oocystis (Chlorophyta) of 8,094,015 cells/L, while zooplankton, namely Euplotes (Ciliophora) was 40,154 ind/L. The index of diversity, uniformity and dominance of phytoplankton ranged from 0.05-1.76, 0.02-0.65 and 0.38-0.99, respectively. Zooplankton has diversity, uniformity and dominance indices ranging from 0-2.03, 0-1 and 0.27-1, respectively.

High dimethylsulfoniopropionate concentrations in the surface seawater over the marginal seas of China and the Northwest Pacific Ocean during May–July of 2021 following La Niña

The total dimethylsulfoniopropionate (DMSPt) concentrations over the surface seawater of China's marginal seas and the northwest Pacific Ocean (NWPO) in May–July 2021 (during the recessional period of La Niña) were analysed. The results showed that the DMSPt concentrations in the marginal seas of China varied from 4.73 to 775.96 nmol L−1, with an average value of 111.42 ± 129.30 nmol L−1 (average ± standard deviation). It was 2–12 times higher than those previously measured in the same seas and in the NWPO in this study. Significant positive correlations between DMSPt, chlorophyll-a and surface seawater temperature (SST) were observed in the SYS, the ECS and the NWPO. Moreover, their abnormally high SST was related to La Niña. These results suggested that high phytoplankton abundance was caused by abnormally high SST following La Niña, which further promoted DMSPt concentration increases. However, the increase of DMSPt was also related to other factors such as nutrients.

The physical factor influencing blooming of phytoplankton in Menjer Lake Wonosobo Indonesia

Phytoplankton are organisms that are sensitive to environmental changes and their presence can be used as an indicator of aquatic productivity. Physical factors in the waters can affect the abundance of phytoplankton. The purpose of this study is to determine the relationship between physical factors (temperature, brightness, TDS and TSS) and the abundance of phytoplankton. Phytoplankton sampling was carried out at 7 stations by purposive random sampling in Menjer Lake including 7 sites of the tourism areas, floating net cages, near agricultural areas, the middle of the lake, spring sources, inlets of the Serayu River and outlet areas. The variables measured were temperature, light penetration, TSS and TDS concentration as well as the composition and abundance of phytoplankton. The results of this study obtained 6 species of phytoplankton, namely Ceratium sp., Dictyosphaerium pulchellum, Microcystis aeruginosa, Microspora sp., Nitzschia sp., and Pediastrum sp. The highest abundance of phytoplankton is Microcystis aeruginosa and temperature in related to season has a strong effect on the abundance of phytoplankton.