Nitrate, Phosphate, Silica and Phytoplankton Abundance in the Coastal Waters of Maitara Island, North Maluku

Background: The presence and abundance of phytoplankton are closely related to the physical and chemical parameters of water. Phytoplankton play a crucial role in aquatic ecosystems as primary producers and nutrient absorbers. This study aims to analyze the relationship between nitrate and phosphate nutrient content and the abundance of phytoplankton in the Arungkeke Waters, Jeneponto Regency. Methods: This research utilized a combination of field measurements and laboratory analysis. Direct measurements in the Arungkeke waters were conducted to assess surface water parameters, including temperature, salinity, current velocity, transparency, and pH. Water samples were collected for laboratory analysis of phytoplankton composition and abundance, as well as nitrate and phosphate concentrations. Regression analysis was performed to determine the relationship between nutrient concentrations and phytoplankton abundance. Findings: The study identified two classes of phytoplankton present in the Arungkeke waters: Bacillariophyceae and Dinophyceae. Oceanographic parameters were measured, with temperature ranging from 28.3°C to 29.7°C, current velocity from 0.039 m/s to 0.073 m/s, salinity from 29.3 ppt to 32 ppt, transparency from 1.9 m to 2.3 m, and pH from 7.3 to 7.4. Nitrate concentrations ranged from 0.042 mg/L to 0.076 mg/L, while phosphate concentrations ranged from 0.046 mg/L to 0.056 mg/L. The regression analysis revealed a moderate relationship between phytoplankton abundance and nutrient concentrations, with an R² value of 0.44. Conclusions: The study concludes that phytoplankton abundance in the Arungkeke Waters is influenced by nitrate and phosphate concentrations, with a moderate correlation observed. The presence of Bacillariophyceae and Dinophyceae classes indicates the ecological significance of these waters as a primary production area. Novelty/Originality of this article: This study provides valuable insights into the interaction between nutrient dynamics and phytoplankton abundance in the Arungkeke Waters, which is a relatively understudied area. By identifying the classes of phytoplankton present and quantifying their relationship with key nutrients, this research contributes to a better understanding of the ecological processes in coastal waters.

Phytoplankton are primary producers that can be used as seawater condition indicators. Certain phytoplankton can proliferate, causing harmful algal blooms (HABs). The coastal waters of South Sulawesi, Indonesia are under pressure from land-based processes and activities resulting in inputs of organic and inorganic materials. This study analysed phytoplankton diversity and abundance in coastal waters around South Sulawesi. Phytoplankton were sampled and seawater parameters (salinity, temperature, turbidity, pH, nitrate concentration) measured in-situ at six stations around seven major river estuaries in three seaways (Makassar Strait, Flores Sea, Gulf of Bone). Phytoplankton taxonomic composition, abundance and indices of diversity (H’), evenness (E), and dominance (D) were analysed. Phytoplankton from 31 species and three classes (Bacillariophyceae, Cyanophyceae, Dinophyceae) were identified. Phytoplankton abundance and community structure differed significantly between sites and seaways but were not significantly correlated with water quality parameters although Dinophyceae abundance correlated significantly with observed pollution levels. Phytoplankton abundance was strongly influenced by the Dinophyceae, especially Ceratium furca, a potential HAB species; Cyanophyceae had the strongest influence on species richness but least on community structure. C. furca abundance was strongly correlated negatively with species richness, H’ and E, and positively with D, indicating negative impacts of this species on phytoplankton communities.

Phytoplankton and bacterial assemblages in ballast water of U.S. military ships as a function of port of origin, voyage time, and ocean exchange practices

Phytoplankton plays an important role in primary productivity in marine environment. Various environmental changes in coastal area will impact the water quality and their phytoplankton compositions. The purpose of this study is to examine the abundance of phytoplankton from two different sites, i.e Tanah Merah (close to mining site) and Semujur Island (away from mining site) in Bangka Island. Phytoplankton and water sample were collected on June- August 2018. Water quality was measured using water quality checker, whereas the phytoplankton was identified under the microscope with a magnification of 100x. Non-parametric Kruskal test and T-test analysis was performed to determine the abundance, diversity, uniform, and dominance of phytoplankton between Sites, respectively. Statistical analyses showed the abundance of phytoplankton at Semujur Island was significantly higher than that at Tanah Merah (p = 0.003). In additions the diversity, uniform, and dominance were also significantly different between sites (all p <0.05). In Semujur Island, Diatoms (Thalassiothrix, Chaetoceros and Thalassionema) were more dominants than the Dinophyceae group. However, in Tanah Merah, the genera Ceratium belong to class Dinophyceae was more dominant than the class Bacillariophyceae. These results performed that the phytoplankton in Tanah Merah and Semujur Island was affected by environment, in this case the mining area. The water quality in Semujur Island (non-mining Area) might have good quality than in Tanah Merah (mining area). The average value of turbidity and Total Suspended Solid in Tanah Merah Waters causes low abundance of phytoplankton. It can be concluded that tin mining can disrupt the abundance and composition of phytoplankton as a primary producer of waters.

Phytoplankton community structure in the Arabian Sea during and after the SW monsoon, 1994

Factors regulating the phytoplankton and tintinnid microzooplankton communities in the East China Sea

The relationship between phytoplankton cell size and abundance has long been known to follow regular, predictable patterns in near steady-state ecosystems, but its origin has remained elusive. To explore the linkage between the size-scaling of metabolic rate and the size abundance distribution of natural phytoplankton communities, we determined simultaneously phytoplankton carbon fixation rates and cell abundance across a cell volume range of over six orders of magnitude in tropical and subtropical waters of the Atlantic Ocean. We found an approximately isometric relationship between carbon fixation rate and cell size (mean slope value: 1.16; range: 1.03-1.32), negating the idea that Kleiber's law is applicable to unicellular autotrophic protists. On the basis of the scaling of individual resource use with cell size, we predicted a reciprocal relationship between the size-scalings of phytoplankton metabolic rate and abundance. This prediction was confirmed by the observed slopes of the relationship between phytoplankton abundance and cell size, which have a mean value of -1.15 (range: -1.29 to -0.97), indicating that the size abundance distribution largely results from the size-scaling of metabolic rate. Our results imply that the total energy processed by carbon fixation is constant along the phytoplankton size spectrum in near steady-state marine ecosystems.

The existence of several species of phytoplankton with potential HABs (Harmful Algal Blooms) was investigated on the coastal waters of Ternate Island. This work aims at describing the distribution, species composition, and the abundance of phytoplankton with potential HABs and their ecological index. Data collection was carried out in August 2022 in the coastal waters of Ternate Island at three research locations, namely in Dorpedu (Station 1), Falajawa, Muhajirin Village (Station 2) and Kulaba (Station 3), respectively. Sampling of phytoplankton uses a filtering method with a plankton net. The results of this study quantified 24 genera of phytoplankton where 11 generas were included the group of potential HABs, namely Leptocylindrus, Coscinodiscus, Pseudo Nitzschia. Rhizosolenia, Chaetoceros, and Nitzschia (Class Bacillariophyceae), Gymnodinium, Protoperidinium, Alexandrium, and Ceratium (Class Dinophyceae), and Phaeocystis (Class Prymnesiophyte). The highest abundance of potential HABs varied between research stations, Rhizosolenia sp. of 7.6388x104 cells/l at station 1, Leptocylindrus sp. of 5.4504x104 cells/l, Phaeocystis sp. of 4.0x104 cells/l at Station 2. On the other hand, the lowest abundance was Nitzschia sp. of 4.1291x102 cells/l at Station 1, Gymnodinium sp. of 4.1291x102 cells/l at Station 2, and Pseudo Nitzschia sp. of 1.2387x103 cells/l at Station 3. Generally, the ecological condition of the phytoplankton community in Ternate Island Waters has a moderate level of species diversity with fairly even distribution of species and no dominance of certain species.

Previous work has documented large fluxes of freshwater and nutrients from submarine groundwater discharge (SGD) into the coastal waters of a few volcanic oceanic islands. However, on the majority of such islands, including Moorea (French Polynesia), SGD has not been studied. In this study, we used radium (Ra) isotopes and salinity to investigate SGD and associated nutrient inputs at five coastal sites and Paopao Bay on the north shore of Moorea. Ra activities were highest in coastal groundwater, intermediate in coastal ocean surface water, and lowest in offshore surface water, indicating that high-Ra groundwater was discharging into the coastal ocean. On average, groundwater nitrate and nitrite (N + N), phosphate, ammonium, and silica concentrations were 12, 21, 29, and 33 times greater, respectively, than those in coastal ocean surface water, suggesting that groundwater discharge could be an important source of nutrients to the coastal ocean. Ra and salinity mass balances indicated that most or all SGD at these sites was saline and likely originated from a deeper, unsampled layer of Ra-enriched recirculated seawater. This high-salinity SGD may be less affected by terrestrial nutrient sources, such as fertilizer, sewage, and animal waste, compared to meteoric groundwater; however, nutrient-salinity trends indicate it may still have much higher concentrations of nitrate and phosphate than coastal receiving waters. Coastal ocean nutrient concentrations were virtually identical to those measured offshore, suggesting that nutrient subsidies from SGD are efficiently utilized.

Monitoring and mapping of major phytoplankton groups (PG) or functional types (PFT) has been targeted as a relevant topic for the understanding and study of marine ecosystem, especially under the present climate change scenario. Developing of algorithms that determine the structure of the phytoplankton communities is a reality since the last 20 years, but not much advanced has been done in the field of image spectroscopy due to the lack of spaceborne sensors with a systematic high temporal and spatial scales. Some operational sensors are changing the game right now, like PRISMA, ENMAP and, in the future, SGB, CHIME and other developments in the hyperspectral dimension. Most of the approaches for determining PFT or PG are based on phytoplankton abundance, cell size or bio-optical properties that use chlorophyll-a or spectral features (absorption, backscatter, and/or reflectance) on water in the VIS-NIR range as inputs. These and other approaches based on machine learning and deep learning are being tested on ENMAP imagery over the Baltic Sea. We will use reflectance data provided by DLR. Comparison of atmospheric correction approaches seems to be a necessary step, and radiance data will be process with current available algorithms. Since ENMAP has 240 bands, and high spatial resolution (30 m), we will tackle the dimensionality reduction problem adapting well-known machine learning approaches to the sensor characteristics (https://isp.uv.es/soft_feature.html).

Interactions between nutrient and biotic components of phytoplankton in Celestún lagoon, a groundwater-influenced tropical coastal lagoon were studied. Gradients of nutrients, chlorophyll a, phaeopigments, production and respiration rates were estimated from March 1990 to March 1991. The inner zone of the lagoon was strongly affected by groundwater discharges with high concentrations of nitrate (35 μmol) and soluble reactive silica (400 μmol). The seaward zone was characterized by high salinity (<30‰) and low concentration of nutrients. The middle zone of the lagoon was characterized by intermediate values of salinity and high concentrations of soluble reactive phosphorus (>9 μmol) and ammonia (15 μmol). Seasonal chlorophyll a variations showed a gradient of high concentrations in the middle region (20–28 mg m-3) to low concentrations at both ends of the lagoon during the rainy season (5–8 mg m-3). Net primary production ranged from 0.1 to 2.2 g C m-3day-1, and showed a similar seasonal pattern in all stations, with a peak in the early rainy season and smaller secondary peak during the ‘nortes’ season. Multivariate analysis was carried out in order to describe different stages of nutrient-phytoplankton coupling. These were related to groundwater discharges and climatic patterns. The relationships between nutrient and phytoplankton showed a coupling between mineralization-import of nutrient patterns and respiration-production of phytoplankton. The dissolved inorganic nitrogen to soluble reactive phosphorus ratio in Celestún lagoon varied seasonally from 70:1 during the dry and rainy seasons, to <5:1 during the ‘nortes’ season. This suggested a potential shift in nutrient limitation for phytoplankton growth.

Nutrient-phytoplankton production relationships in a groundwater-influenced tropical coastal lagoon

The waters of Yapen Timur in Yapen Islands, Papua are semi-open waters with high potential natural resources. Recent research on chemical and biological parameters more specifically of nutrient concentration and phytoplankton abundance is still very limited. The study aimed to observe the concentration of nutrients (nitrates and phosphates), and their relation with the abundance of phytoplankton in Yapen Timur waters, was conducted on January 5 Th to February 5 th , 2016. Using explorative method and purposive sampling method, with 15 sampling points. Data analysis using Spectrophotometer at wavelength 545 nm for nitrate and 885 nm, whereas for phytoplankton abundance use APHA equation. Spatial distribution of nitrate, phosphate and phytoplankton abundance using kriging-method equation and Software Ermaper 7.0. Nitrate concentrations were found to be between 0.2 mg - 0.7 mg / l, phosphates ranging from 0.2 to 0.6 mg / l and the abundance of phytoplankton ranged from 49,682 to 139,490 ind / l. The correlation coefficient analysis indicates the relationship between nitrite and phytoplankton of 0.3947, phosphate and phytoplankton of. 0.0068. The concentration of nitrate and phosphate at the observation site indicated that the water quality belongs to the oligotrophic waters, the abundance of phytoplankton is high and there is no blooming in certain species, and the relationship between the nitrate and phosphate concentration is positively correlated with the abundance of phytoplankton at the observation site.

Phytoplankton is a vital and important organism as a producer of the primary food supply of the marine and freshwater food webs. This study is conducted to investigate the variability of phytoplankton abundance related to environmental variables in the Terengganu River Estuary, by using statistical analysis. Total of ten water samples were collected, of which three stations were in the estuary and seven stations were in the coastal water. A total of 124 taxa of 55 genera, belonging to six taxonomic classes were observed at the study area. The order of phytoplankton abundance was diatoms > blue-green algae > golden-brown algae > dinofalgellates > green algae > euglenoids. The phytoplankton abundance was higher in the coastal area compared to the estuary, with the maximum density 764.10 cells mL-1 and 157.40 cells mL-1 respectively. It was recorded that 10.96% of the total abundance from the data collection was registered in the estuary, while the remaining 89.04% were logged in the coastal region. The freshwater phytoplankton was dominated by golden-brown algae (Chrysophyceae), while marine phytoplankton was governed by diatoms and blue-green algae. It was observed that the water temperature and salinity were positively correlated with marine phytoplankton but negatively related to freshwater phytoplankton. High levels of water temperature and hypersalinity at the coastal region was observed to enhance the production rate in the coastal region. In contrast, the nutrients were positively related to freshwater phytoplankton, but negatively correlated to the marine phytoplankton, which results in low concentrations of nutrients in the coastal region that could be caused by intensive uptake by the abundance of marine phytoplankton. This study revealed that environmental variables are an important element in determining the phytoplankton community compositions in the tropical region.

The Eastern Mediterranean and its Cilician Basin offshore waters have oligotrophic features with low nutrient concentrations, low primary production, and high water transparency. However, the wide shelf area of the Cilician Basin is subject to contaminated river inflows with enhanced nutrient loads and direct discharges of urban wastewaters of southern Turkey, leading to develop local eutrophic/mesotrophic conditions in the inner sites of Mersin and Iskenderun Bays on the Cilician Basin. For the assessment of changing trophic status of the coastal and the bay water bodies under anthropogenic pressures since the 1980s, five extensive field studies were performed in summer and winter periods of 2014, 2015, and 2016. Physical and eutrophication-related biochemical parameters (salinity, temperature, Secchi Disk Depth, nutrients, dissolved oxygen, chlorophyll-a) were measured at 65 stations in different water bodies occupying the Northeastern (NE) Mediterranean coastal, offshore areas and bays. The collected data sets were used in scaling the trophic status of the visited water bodies of NE Mediterranean coastal, offshore areas and semi-enclosed bays, using novel classification tools of Trophic Index (TRIX), Eutrophication Index (E.I.), chl-a, and HELCOM Eutrophication Assessment Tool (HEAT), developed by different experts for highly productive seas. These tools, which can successfully classify highly productive coastal water masses under human pressures, and their sensitivities have been tested for scaling of the current trophic status of the NE Mediterranean coastal water bodies being subject to human pressures. The scaling results of classical TRIX, E.I., and chl-a indices in the NE Mediterranean water masses are not sensitive enough to differentiate mesotrophic and eutrophic water bodies because these indices principally assume to have higher concentrations of eutrophication-related parameters in the least effected (reference) water bodies. The HEAT tool, which uses a site-specific "reference value" for each eutrophication-indicator, has allowed us to produce more reliable and sensitive scaling of the current trophic status of the NE Mediterranean shelf areas, even though we used only the "reference values" derived from the composite data sets. The results of the indices were compared with the HEAT tool and the actual status was assessed from observations, indicating revision requirements of the multi-metric classification tools. For this goal, scales of natural (oligotrophic) and anthropogenic (eutrophic) levels of eutrophication indicators should be determined at a sub-basin scale using long-term site-specific observations in the NE Mediterranean. The revised scale ranges of TRIX for oligotrophic, mesotrophic, and eutrophic water bodies of Mersin Bay are in line with ranges of TRIX classification tool proposed for Aegean Sea waters, which can be used to assess trophic status of the entire Eastern Mediterranean and Aegean coastal seas (surface salinity > 37.5) having oligotrophic properties in the offshore waters.