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Chlorophyll a concentration is an important indicator to characterize phytoplankton biomass, which further reflects the water quality of lakes. Based on the data of chlorophyll a concentration and environmental factors extracted from the ChlaData, HydroLAKES, and HELLAKES databases for Chinese lakes for three years (2000, 2005, and 2010), we used the random forest model and the generalized linear model to analyze the relationship between chlorophyll a concentration and environmental factors in Chinese lakes and predict the chlorophyll a concentration. The results showed that the relative importance of environmental factors for chlorophyll a was as follows: nutrient salt concentration > longitude and latitude > monthly mean precipitation > altitude > annual average temperature. The coefficient of determination of the random forest model was 0.9997 (R2 = 0.9997), and the root-mean-square error was 0.0010 (RMSE = 0.0010), with high prediction accuracy. The random forest model and the generalized linear model both showed that TP was the main influencing factor of chlorophyll a concentration. The validation results based on the measured data show that the models are reliable. By making more accurate predictions of chlorophyll a concentrations, we can facilitate the prevention, control, and treatment of lake blooms.

Lake eutrophication is a global water environmental problem and has become a research focus nowadays. Chlorophyll a concentration is an important index in terms of evaluating lake eutrophication. The aim of this study was to build an effective and universal empirical model for simulation of chlorophyll a concentration in Donghu Lake. On the basis of the relationship between chlorophyll a concentration and dissolved oxygen (DO), water temperature (T), total nitrogen (TN), and total phosphorus (TP), models for simulating chlorophyll a concentration were built by using simulated annealing (SA), genetic algorithm (GA), artificial bee colony (ABC), and particle swarm optimization (PSO) to optimize parameters of support vector machine (SVM). Moreover, a collaborative mode (Col-SVM model) was built by introducing data assimilation, and meanwhile, accuracy and universality of the model were studied. Modeling results showed that the application of optimization algorithms and data assimilation improved the performance of modeling based on SVM. Model simulation results demonstrated that the Col-SVM model has high accuracy, decent stability, and good simulation effect; the root mean square error (RMSE), mean absolute percentage error (MAPE), Nash–Sutcliffe efficiency coefficient (NSE), bias, and mean relative error (MRE) between simulated values and observed values were 10.07 μg/L, 0.31, 0.96, −0.050, and 0.15, respectively. In addition, model universality analysis results revealed that the Col-SVM model has good universality and can be used to simulate the chlorophyll a concentration of Donghu Lake at different times. Overall, we have built an effective and universal simulation model of chlorophyll a concentration that provides a new idea and method for chlorophyll a concentration modeling.

2013年５月から12月までの月１回、月見ヶ池表層の５地点において栄養塩およびクロロフィルa濃度の測定と、動植物プランクトン群集の同定と計数を行った。硝酸塩＋亜硝酸塩は調査期間を通して平均50 μmol L－ 1であったが、リン酸塩濃度は最も高い９月においても0.16 μmol L－ 1 であった。N/P比は400以上と非常に高く、植物プランクトンはリンの制限を受けやすい環境であった。クロロフィルa 濃度は７月と８月に＞20 μg L－ 1 と他の月よりも高い値を示し、その他の月は＜10 μg L－ 1 であった。植物プランクトンは調査期間を通して７月を除くとラン藻のPhormidium属が優占していた。一方、動物プランクトンはBrachionus属が５月に、Bosmina属が６月に、カイアシ類のnauplius幼生が７月から10月に多く観察され、富栄養湖の特徴を有していた。動物プランクトン現存量はキショウブ（Iris pseudacorus）近くの場所の方がキショウブから離れた場所よりも有意に高い値を示した。抽水植物のある池は抽水植物のない池よりもより多くの動物プランクトンを保持することが出来るようである。

Purpose. Data from the immersion fluorescence sensors of the CTD complex and BioArgo floats are widely used for studying spatial and temporal variability of the chlorophyll a concentration on large scales. In these devices the fluorescence sensors are not equipped with a dark chamber; as a result, a part of the reaction centers of photosystem 2 is closed due to the sunlight effect. It is manifested in decrease of the measured fluorescence intensity in the upper mixed layer due to fluorescence quenching, while the chlorophyll a concentration can remain unchanged. The purpose of the work is to develop the algorithm for correcting the fluorescence quenching. Methods and Results. It is shown that photosynthetically available radiation decreases with depth within the upper mixed layer by almost an order, and the chlorophyll a fluorescence measured by the immersion sensor (without a dark chamber), increases with depth in this layer. Relationship between light intensity and share of open reaction centers of photosystem 2 in cell of microalgae was revealed. The relationship is described by the exponential function. The share of open centers effects on the degree of fluorescence intensity decreasing and therefore on fluorescence quenching induced by light. Conclusions. The universal algorithm for correcting fluorescence quenching in the upper mixed layer is proposed. Due to its correction, almost uniform fluorescence distribution is obtained in the upper mixed layer which is in a good consistence with the results of chlorophyll a concentration measurements in situ.

Low- and medium-resolution satellites have been a relatively mature platform for inland eutrophic water classification and chlorophyll a concentration (Chl-a) retrieval algorithms. However, for oligotrophic and mesotrophic waters in small- and medium-sized reservoirs, problems of low satellite resolution, insufficient water sampling, and higher uncertainty in retrieval accuracy exist. In this paper, a hybrid Chl-a estimation method based on spectral characteristics (i.e., remote sensing reflectance (Rrs)) classification was developed for oligotrophic and mesotrophic waters using high-resolution satellite Sentinel-2 (A and B) data. First, 99 samples and quasi-synchronous Sentinel-2 satellite data were collected from four small- and medium-sized reservoirs in central China, and the usability of the Sentinel-2 Rrs data in inland oligotrophic and mesotrophic waters was verified by accurate atmospheric correction. Second, a new optical classification method was constructed based on different water characteristics to classify waters into clear water, phytoplankton-dominated water, and water dominated by phytoplankton and suspended matter together using the thresholds of Rrs490/Rrs560 and Rrs665/Rrs560. The proposed method has a higher classification accuracy compared to other classification methods, and the band-ratio algorithm is simpler and more effective for satellite sensors without NIR bands. Third, given the sensitivity of the empirical method to water variability and the ease of development and implementation, a nonlinear least squares fitted one-dimensional nonlinear function was established based on the selection of the best-fitting spectral indices for different optical water types (OWTs) and compared with other Chl-a estimation algorithms. The validation results showed that the hybrid two-band method had the highest accuracy with squared correlation coefficient, root mean squared difference, mean absolute percentage error, and bias of 0.85, 2.93, 32.42%, and −0.75 mg/m3, respectively, and the results of the residual values further validated the applicability and reliability of the model. Finally, the performance of the classification and estimation algorithms on the four reservoirs was evaluated to obtain images mapping the Chl-a in the reservoirs. In conclusion, this study improves the accuracy of Chl-a estimation for oligotrophic and mesotrophic waters by combining a new classification algorithm with a two-band hybrid model, which is an important contribution to solving the problem of low resolution and high uncertainty in the retrieval of Chl-a in oligotrophic and mesotrophic waters in small- and medium-sized reservoirs and has the potential to be applied to other optically similar oligotrophic and mesotrophic lakes and reservoirs using similar spectrally satellite sensors.

The Indo-Pacific humpback dolphin (Sousa chinensis) has been reported to prefer estuary habitats. This study explored the environmental factors affecting a critically endangered population off the coast of Yunlin, Taiwan. We measured dolphin sighting rates and estuary characteristics affected by the watershed, including seven physical factors (watershed rainfall, watershed runoff, estuarine turbidity, pH, salinity, temperature, and dissolved oxygen) and two biological factors (estuarine net primary production and chlorophyll a concentration), at the Hsinhuwei River estuary in Taiwan. Dolphin activity was measured by sighting rate and behavioral indices for feeding and traveling between 2017 and 2018. We observed that when the maximum net production increased alongside rising temperatures in spring, both the dolphin sighting rate and foraging activity increased. This trend was maintained until heavy rainfall or increased river runoff occurred during late summer, which resulted in high turbidity in autumn and winter. Turbidity was significantly negatively correlated with dolphin activity (sighting rate and foraging). Furthermore, we found that dolphin traveling positively correlated with the chlorophyll a concentration and maximum net production factors, which could attract dolphins expecting more abundant prey fish in the estuary supported by the high primary production. This study provides empirical evidence on how estuary characteristics affected by the watershed can affect the sighting rate and behavioral activities of Indo-Pacific humpback dolphins.

Priority Marine Regions (PMR) are important areas for biodiversity conservation in the Northwest Pacific Ocean in Mexico. The oceanographic dynamics of these regions are very important to understand their variability, generate analyses, and predict climate change trends by generating an adequate management of marine resources and their ecological characterization. Chlorophyll a (Chl a) is important to quantify phytoplankton biomass, consider the main basis of the trophic web in marine ecosystems, and determine the primary productivity levels and trends of change. The objective of this research is to analyze the oceanographic variability of 24 PMR through monthly 1-km satellite image resolution Chl a data from September 1997 to October 2018. A cluster analysis of Chl a data yielded 18 regions with clear seasonal variability in the Chl a concentration in the South-Californian Pacific (maximum values in spring-summer and minimum ones in autumn-winter) and Gulf of California (maximum values in winter-spring and minimum ones in summer-autumn). Significant differences (p < 0.05) were observed in Chl a concentration analyses for each one of the regions when climate patterns—El Niño/La Niña Southern Oscillation (ENSO) and normal events—were compared for all the seasons of the year (spring, summer, autumn, and winter).

The typhoon Wind-Pump induced upwelling and cold eddy often promote the significant growth of phytoplankton after the typhoon. However, the importance of eddy-pumping and wind-driven upwelling on the sea surface chlorophyll a concentration (Chl-a) during the typhoon are still not clearly distinguished. In addition, the air–sea heat flux exchange is closely related to the upper ocean processes, but few studies have discussed its role in the sea surface Chl-a variations under typhoon conditions. Based on the cruise data, remote sensing data, and model data, this paper analyzes the contribution of the vertical motion caused by the eddy-pumping upwelling and Ekman pumping upwelling on the surface Chl-a, and quantitatively analyzes the influence of air–sea heat exchange on the surface Chl-a after the typhoon Linfa over the northeastern South China Sea (NSCS) in 2009. The results reveal the Wind Pump impacts on upper ocean processes: (1) The euphotic layer-integrated Chl-a increased after the typhoon, and the increasing of the surface Chl-a was not only the uplift of the deeper waters with high Chl-a but also the growth of the phytoplankton; (2) The Net Heat Flux (air–sea heat exchange) played a major role in controlling the upper ocean physical processes through cooling the SST and indirectly increased the surface Chl-a until two weeks after the typhoon; (3) the typhoon-induced cyclonic eddy was the most important physical process in increasing the surface Chl-a rather than the Ekman pumping and wind-stirring mixing after typhoon; (4) the spatial shift between the surface Chl-a blooms and the typhoon-induced cyclonic eddy could be due to the Ekman transport; (5) nutrients uplifting and adequate light were two major biochemical elements supplying for the growth of surface phytoplankton.

With the rapid expansion of modern society in both industrial and technological aspect, it is becoming important to assess the risk of compounds which are released daily in our environment in enormous quantities. For this reason, a broad spectrum of ecotoxicological assays with various model organisms has been developed. In this study, toxicity of the Sava River has been assessed by using different model organisms: freshwater algae Chlorella vulgaris, clover Trifolium repens, common wheat Triticum aestivum and zebrafish Danio rerio embryos. Model organisms have been exposed to filtered samples of the Sava River from five different locations (Jesenice, Jankomir, Hrušćica, Rugvica, and Lukavec). Pollution profiles of samples were assessed by chemical analysis. Exposure of Chlorella vulgaris to samples caused growth inhibition and decreased chlorophyll a concentration. Root and/or sprout elongation of Trifolium repens and Triticum aestivum was observed to have lowest rates after exposure to same samples in both model organisms. Exposing the zebrafish embryos to samples resulted in minor mortality rate and sublethal effects. Activity of ABC transporters was inhibited in all samples. The use of these ecotoxicological bioassays, combined with chemical analysis, has resulted in comprehensive toxicity assessment of water from five different sites in Sava River, offering basis for monitoring of lentic and lotic waters. Uzevši u obzir brzo širenje modernog društva u industrijskom i tehnološkom aspektu, postaje nužno procijeniti rizik tvari koje se svakodnevno ispuštaju u naš okoliš u velikim količinama. U tu svrhu, razvijen je široki spektar ekotoksikoloških testova na različitim modelnim organizmima. Unutar ovog rada, istraživana je toksičnost rijeke Save upotrebom različitih modelnih organizama: slatkovodne alge Chlorella vulgaris, djeteline Trifolium repens, pšenice Triticum aestivum i embrija ribe zebrice Danio rerio. Modelni organizmi izlagani su filtriranim uzorcima rijeke Save s pet lokacija (Jesenice, Jankomir, Hrušćica, Rugvica i Lukavec). Prisutnost toksikanata na ovim postajama utvrđena je kemijskom analizom vode. Izloženost alge Chlorella vulgaris uzorcima uzrokovala je inhibiciju njihovog rasta i smanjenu koncentraciju klorofila a. Produljenje korijenja i/ili izdanka kod vrsta Trifolium repens i Triticum aestivum imalo je najnižu stopu nakon izloženosti istim uzorcima kod oba modelna organizma. Izlaganje embrija zebrica uzorcima rezultiralo je niskom stopom mortaliteta i subletalnih efekata. Aktivnost ABC transportera kod zebrica inhibirana je prilikom izlaganja svim ispitivanim uzorcima. Ovakva upotreba ekotoksikoloških testova u kombinaciji s kemijskom analizom, omogućila je sveobuhvatnu procjenu toksičnosti uzoraka rijeke Save s pet različitih postaja, ali i pružila temelj za praćenje stanja tekućica i stajaćica.

With the rapid expansion of modern society in both industrial and technological aspect, it is becoming rather important to assess the risk of compounds which are released daily in our environment in enormous quantities. For this reason, a broad spectrum of ecotoxicological assays with various model organisms has been developed, in order to assess toxic effects that these compounds might cause. In this study, toxicity of the Sava River has been assessed by using different model organisms with different sensitivities to the various kinds of pollutants and their mixtures: freshwater algae Chlorella vulgaris, clover Trifolium repens, common wheat Triticum aestivum and the zebrafish Danio rerio embryos. Model organisms have been exposed to filtered samples of the Sava River from five different locations (Jesenice, Jankomir, Hrušćica, Rugvica, and Lukavec), with different pollution profiles, which was assessed by chemical analysis of 571 organic pollutants. The use of ecotoxicological bioassays performed on different model organisms, combined with chemical analysis, has provided an accurate toxicity assessment of water from the Sava River, allowing us to define and divide the sampling sites accordingly.

Standard NASA ocean color algorithm OC4 was developed on the basis of ocean optical data and while appropriate for Case 1 oceanic waters could not be adequately applied for the Black Sea waters due to its different bio-optical properties. OC4 algorithm is shown to overestimate chlorophyll concentration (Chl-a) in summer and underestimate Chl-a during early spring phytoplankton blooms in the Black Sea. For correct conversion of satellite data to Chl-a, primary production and other indicators regional algorithms should be developed taking into account bio-optical properties of the Black Sea waters. Light absorption by phytoplankton pigments – a_ph (λ) have been measured in open sea and shelf Black Sea waters in different seasons since 1998. It was shown that the first optical depth was located within the upper mixed layer (UML) for most of the year with the exception of the spring when seasonal stratification was developing. As a result spectral features of water leaving radiance were determined by optical properties of the UML. Significant seasonal differences in Chl-a specific light absorption coefficients of phytoplankton within UML have been revealed. These differences were caused by adaptive changes of composition and intracellular pigment concentration due to variable environment conditions – mainly light intensity. Empirical relationships between a_ph (λ) and Chl-a were derived by least squares fitting to power functions for different seasons. Incorporation of these results will refine the regional ocean color models and provide improved and seasonally adjusted estimates of chlorophyll a concentration, downwelling radiance and primary production in the Black Sea based on satellite data.

During the past 20 years, the ecological environment of Dianchi Lake has been adversely affected by climate change and human activities, which directly affected the ecosystem and biodiversity of the Dianchi Lake watershed. Analyzing the spatiotemporal variation of chlorophyll a (Chla) concentration of Dianchi Lake and exploring the internal and external factors effect on Chla concentration is the basis for controlling and improving the water ecological environment of Dianchi Lake, and it is also the key to prevent and control the water pollution of Dianchi Lake. In this study, the water quality of Dianchi Lake was examined using 12 water quality indicators from 10 water quality monitoring sites for the duration between 2000 to 2017. The changing characteristics of Chla in the context of internal and external factors were analyzed. The spatiotemporal evolution process of Chla concentration in the past 20 years was also evaluated. The results indicated that Chla concentration was significantly and positively correlated with the chemical oxygen demand (CODCr), the Dianchi Lake watershed gross domestic product (GDP), and the impervious surface area (ISA) of the watershed, in addition to the total phosphorus (TP), biochemical oxygen demand (BOD5), ammonia hydrogen (NH3-N), water temperature (WT), and civil vehicle ownership. Moreover, a significant and negative correlation was noticed between Dianchi Lake watershed GDP and NH3-N, BOD5, TP, total nitrogen (TN), and comprehensive nutrition state index (TLI). The Dianchi Lake population was negatively correlated with TP, TLI, and BOD5. The concentration of Chla in Dianchi Lake was affected by both internal factors, and external factors such as anthropogenic activities, the latter of which was the main cause of the continuous deterioration of the lake water quality.

Since the impoundment of the Three Gorges Reservoir in 2003, algal blooms have frequently been observed in it. The chlorophyll a concentration is an important parameter for evaluating algal blooms. In this study, the chlorophyll a concentration in Xiangxi Bay, in the Three Gorges Reservoir, was predicted using HJ-1 satellite imagery. Several models were established based on a correlation analysis between in situ measurements of the chlorophyll a concentration and the values obtained from satellite images of the study area from January 2010 to December 2011. Chlorophyll a concentrations in Xiangxi Bay were predicted based on the established models. The results show that the maximum correlation is between the reflectance of the band combination of B4/(B2+B3) and in situ measurements of chlorophyll a concentration. The root mean square errors of the predicted values using the linear and quadratic models are 18.49 mg/m3 and 18.52 mg/m3, respectively, and the average relative errors are 37.79% and 36.79%, respectively. The results provide a reference for water bloom prediction in typical tributaries of the Three Gorges Reservoir and contribute to large-scale remote sensing monitoring and water quality management.

Multiple data sets were combined to investigate five dust storm events over East Asia in spring 2010 and their impacts on chlorophyll in the East China Sea (ECS) and the North Pacific Subtropical Gyre (NPSG). Satellite-observed column aerosol images were able to show the spatial distribution of the transport of dust from the source regions to the two seas for some of the dust storm events. The CALIPSO satellite showed the vertical structure of dust aerosol for a greater number of dust storm events, including some weak events. This was confirmed by simulations of dust deposition and backward trajectories traced to dust source regions. The simulated dust deposition flux for five dust storms ranged from 13.0 to 145.6 mg·m−2·d−1 in the ECS and from 0.6 to 5.5 mg·m−2·d−1 in the NPSG, suggesting that the highest deposition was about one order of magnitude higher than the lowest. The estimated nutrients from dust showed that dust containing iron had the greatest effect on phytoplankton growth in both seas; the iron deposited by one dust storm event accounted for at least 5% of growth and satisfied the increase in demand required for chlorophyll a concentration.

The sea surface temperature (SST) and chlorophyll-a concentration (CHL-a) were analysed in the Gulf of Tadjourah from two set of 8-day composite satellite data, respectively from 2008 to 2012 and from 2005 to 2011. A singular spectrum analysis (SSA) shows that the annual cycle of SST is strong (74.3% of variance) and consists of warming (April-October) and cooling (November-March) of about 2.5C than the long-term average. The semi-annual cycle captures only 14.6% of temperature variance and emphasises the drop of SST during July-August. Similarly, the annual cycle of CHL-a (29.7% of variance) depicts high CHL-a from June to October and low concentration from November to May. In addition, the first spatial empirical orthogonal function (EOF) of SST (93% of variance) shows that the seasonal warming/cooling is in phase across the whole study area but the southeastern part always remaining warmer or cooler. In contrast to the SST, the first EOF of CHL-a (54.1% of variance) indicates the continental shelf in phase opposition with the offshore area in winter during which the CHL-a remains sequestrated in the coastal area particularly in the south-east and in the Ghoubet Al-Kharab Bay. Inversely during summer, higher CHL-a quantities appear in the offshore waters. In order to investigate processes generating these patterns, a multichannel spectrum analysis was applied to a set of oceanic (SST, CHL-a) and atmospheric parameters (wind speed, air temperature and air specific humidity). This analysis shows that the SST is well correlated to the atmospheric parameters at an annual scale. The windowed cross correlation indicates that this correlation is significant only from October to May. During this period, the warming was related to the solar heating of the surface water when the wind is low (April-May and October) while the cooling (November-March) was linked to the strong and cold North-East winds and to convective mixing. The summer drop in SST followed by a peak of CHL-a, seems strongly correlated to the upwelling. The second EOF modes of SST and CHL-a explain respectively 1.3% and 5% of the variance and show an east-west gradient during winter that is reversed during summer. This work showed that the seasonal signals have a wide spatial influence and dominate the variability of the SST and CHL-a while the east-west gradient are specific for the Gulf of Tadjourah and seem induced by the local wind modulated by the topography.

The remote sensing reflectance R rs , concentrations of chlorophyll a and other pigments C i , suspended particulate matter concentrations C SPM and coloured dissolved organic matter absorption coefficient a CDOM (λ) were measured in the euphotic zones of 15 Pomeranian lakes in 2007–2010. On the basis of 235 sets of data points obtained from simultaneous estimates of these quantities, we classified the lake waters into three types. The first one, with the lowest a CDOM (440 nm) (usually between 0.1 and 1.3 m −1 and chlorophyll a concentrations 1.3 C a −3 ), displays a broad peak on the reflectance spectrum at 560–580 nm and resembles the shape of the remote sensing reflectance spectra usually observed in the Baltic Proper. A set of R rs spectra from the Baltic Proper is given for comparison. The second lake water type has a very high CDOM absorption coefficient (usually a CDOM (440 nm) > 10 m −1 , up to 17.4 m −1 in Lake Pyszne; it has a relatively low reflectance ( R rs −1 ) over the entire spectral range, and two visible reflectance spectra peaks at ca 650 and 690–710 nm. The third type of lake water represents waters with a lower CDOM absorption coefficient (usually a CDOM (440 nm) −1 ) and a high chlorophyll a concentration (usually C a > 4 mg m −3 , up to 336 mg m −3 in Lake Gardno). The remote sensing reflectance spectra in these waters always exhibit three peaks ( R rs > 0.005 sr −1 ): a broad one at 560–580 nm, a smaller one at ca 650 nm and a well-pronounced one at 690–720 nm. These R rs (λ) peaks correspond to the relatively low absorption of light by the various optically active components of the lake water and the considerable scattering (over the entire spectral range investigated) due to the high SPM concentrations there. The remote sensing maximum at λ ≈ 690–720 nm is higher still as a result of the natural fluorescence of chlorophyll a . Empirical relationships between the spectral reflectance band ratios at selected wavelengths and the various optically active components for these lake waters are also established: for example, the chlorophyll a concentration in surface water layer C a = 6.432 e 4.556 X , where X = [max R rs (695 ≤ λ ≤ 720) – R rs (λ = 670)]/max R rs (695 ≤ λ ≤ 720), and the coefficient of determination R 2 = 0.95.

The remote sensing reflectance Rrs, concentrations of chlorophyll a and other pigments Ci, suspended particulate matter concentrations CSPM and coloured dissolved organic matter absorption coefficient aCDOM(λ) were measured in the euphotic zones of 15 Pomeranian lakes in 2007-2010. On the basis of 235 sets of data points obtained from simultaneous estimates of these quantities, we classified the lake waters into three types. The first one, with the lowest aCDOM(440 nm) (usually between 0.1 and 1.3 m-1 and chlorophyll a concentrations 1.3 < Ca < 33 mg m-3), displays a broad peak on the reflectance spectrum at 560-580 nm and resembles the shape of the remote sensing reflectance spectra usually observed in the Baltic Proper. A set of Rrs spectra from the Baltic Proper is given for comparison. The second lake water type has a very high CDOM absorption coefficient (usually aCDOM(440 nm) > 10 m-1, up to 17.4 m-1 in Lake Pyszne; it has a relatively low reflectance (Rrs < 0.001 sr-1) over the entire spectral range, and two visible reflectance spectra peaks at ca 650 and 690-710 nm. The third type of lake water represents waters with a lower CDOM absorption coefficient (usually aCDOM(440 nm) < 5 m-1) and a high chlorophyll a concentration (usually Ca > 4 mg m-3, up to 336 mg m-3 in Lake Gardno). The remote sensing reflectance spectra in these waters always exhibit three peaks (Rrs > 0.005 sr-1): a broad one at 560-580 nm, a smaller one at ca 650 nm and a well-pronounced one at 690-720 nm. These Rrs(λ) peaks correspond to the relatively low absorption of light by the various optically active components of the lake water and the considerable scattering (over the entire spectral range investigated) due to the high SPM concentrations there. The remote sensing maximum at λ ≈ 690-720 nm is higher still as a result of the natural fluorescence of chlorophyll a. Empirical relationships between the spectral reflectance band ratios at selected wavelengths and the various optically active components for these lake waters are also established: for example, the chlorophyll a concentration in surface water layer Ca = 6.432 e4.556X, where X = [max Rrs (695 ≤ λ ≤ 720) - Rrs(λ = 670)] / max Rrs (695 ≤ λ ≤ 720), and the coefficient of determination R2 = 0.95.

The aim of the study was to measure the transparent exopolymerparticles (TEP) concentration in cultures of Anabaena flos-aquae OL-K10and to determine the relationship between the quantity of particlesproduced and the light intensity, the age of the culture andthe presence of nitrogen in the culture medium. This is the firsttime TEP production has been investigated in the Nostocales,an order of nitrogen-fixing phytoplankton species. The resultsshowed that TEP production depends on the presence of nitrogenin the culture medium. The longer the culture is grown, the higherthe correlation between its TEP content and its chlorophyll aconcentration.

We have been developing a wireless sensor network system to monitor the quality of lake water in real time. It consists of a sensor module and a system module, which includes communication and power modules. We have focused on pH, turbidity and chlorophyll a concentration as the criteria for qualifying lake water quality. These parameters will be detected by a microfluidic device based sensor module embedded in the wireless sensor network system. In order to detect the turbidity and the chlorophyll a concentration simultaneously, we propose a simple optical measurement method using LED and photodiode in this paper. Before integrating a turbidity and chlorophyll a concentration sensor into the microfluidic device based pH sensor, we performed feasibility studies such as confirmation of the working principle and experiments using environmental water samples. As a result, we successfully verified our simultaneous sensing method by using a simple optical setup of the turbidity and the chlorophyll a concentration.

10 pages, 6 figures, During the last decade the number of seawater dimethylsulfide (DMS) concentration measurements has increased substantially. The importance this gas, emitted from the ocean to the atmosphere, may have in the cloud microphysics and hence in the Earth albedo and radiation budget, makes it necessary to accurately reproduce the global distribution. Recently, the monthly global DMS climatology has been updated taking advantage of the threefold increased size and better resolved distribution of the observations available in the DMS database. Here, the emerging patterns found with the previous versions of the database and climatology are explored with the updated versions. The statistical relationships between the seasonalities of DMS concentrations and other variables are re-examined. The positive correlation previously found between surface seawater DMS and the daily-averaged climatological solar radiation dose in the upper mixed layer of the open ocean is confirmed with both the updated DMS database and climatology. Re-examination of the latitudinal match-mismatch between the seasonalities of DMS and phytoplankton, represented by the chlorophyll a concentration, reveals that they are highly positively correlated in latitudes higher than 40°, but anti-correlated in the 20°-40° latitudinal bands of both hemispheres. Overall, these global emerging patterns provide key information to further understanding the factors that control the emission of volatile sulfur from the ocean. The large uncertainties associated with the methodologies used in global computations, however, call for caution in using these emerging patterns as predictive tools, and prompt to the design of time series and process-oriented studies aimed at testing the validity of the observed relationships. © 2011 Springer Science+Business Media B.V., This work was supported by the Spanish Ministry of Science and Innovation through the projects MIMOSA, PRISMA and Malaspina 2010, and through a PhD studentship to A.L.

Seasonal variations in size-fractionated chlorophyll a concentration were investigated at two stations located in the inner and central areas of Kagoshima Bay from April 2001 to May 2002. Chlorophyll a concentrations at the inner station were several folds higher than those at the central station. At both stations, chlorophyll a concentrations showed large seasonal fluctuations throughout the year which resulted from micro-sized phytoplankton. Vertical distributions of chlorophyll a concentrations showed slightly different patterns between the two size classes. A surface distribution was observed for pico/nano-sized phytoplankton throughout the year. A high chlorophyll a concentration of micro-sized phytoplankton was limited in the surface water during the summer, and extended downward during autumn to winter. Although they suddenly disappeared from the water column during January to February, the chlorophyll a concentration was kept high thereafter. Compared with the annual mean wet and dry weights, Zooplankton biomass in the inner area was slightly higher than that in the central area. The zooplankton biomass was high during June to July and during February to May in the central area, but an additional peak in November was observed in the inner area.

Size fractionated chlorophyll a concentrations at sea surface were investigated from May 2001 to May 2002 at the two stations in the inner and center area of Kagoshima Bay. Chlorophyll a concentrations in the inner area were much higher than those in the center area. Highly fluctuated chlorophyll was observed at both stations and was resulted from a rapid increase of micro-sized phytoplankton. Pico- and nano-sized phytoplankton were more predominated in the center area, althoughmicro-sized phytoplankton was abundant in the inner area., SECTION TWO: PHYSICAL GEOGRAPHY: Report 6

This article is the first in a series of three describing the modelling of the vertical different photosynthetic and photoprotecting phytoplankton pigments concentration distributions in the Baltic and their interrelationsdescribed by the so-called non-photosynthetic pigment factor.The model formulas yielded by this research are an integral part of the algorithms used in the remote sensingof the Baltic ecosystem. Algorithms of this kind have already been developed by our team from data relating mainly to oceanic Case 1 waters (WC1) and have produced good results for these waters. But their application to Baltic waters, i.e.,Case 2 waters, was not so successful. On the basis of empirical data for the Baltic Sea, we therefore derived new mathematical expressions for the spatial distribution of Baltic phytoplankton pigments. They are discussed in this series of articles. This first article presents a statistical model for determining the total concentration ofchlorophyll, a (i.e., the sum of chlorophylls a+pheo derived spectrophotometrically) at different depths in the Baltic Sea Ca(z) on the basis of its surface concentration Ca(0),which can be determined by remote sensing. This model accounts for the principal features of the vertical distributions of chlorophyll concentrations characteristic of the Baltic Sea. The model's precision was verified empirically: it was found suitable for application in the efficient monitoring of the Baltic Sea. The modified mathematical descriptions of the concentrations of accessory pigments (photosynthetic and photoprotecting) in Baltic phytoplankton and selected relationships between them are given in the other two articles in this series (Majchrowski et al. 2007, Woźniak et al. 2007b, both in this volume).

A microcosm experiment was carried out during early spring 1994 in order to investigate the effect of Si-sufficient but low N:P ratio or high N:P ratio nutrient inputs, added at different frequencies, on phytoplankton succession patterns. Eight Perspex cylinders were filled with 30 1 of coastal water from Masnou (20 km north of Barcelona) and placed in a chamber at 17°C under a 12:12 h light:dark photoperiod. Four experimental conditions were randomly assigned to duplicate containers: low N:P ratio (N-deficient) or high N:P ratio (P-deficient) nutrient inputs (including sufficient Si in all cases), in combination with addition intervals of 2 or 6 d. Integrated chlorophyll a (chl a) concentrations in the P-deficient containers were significantly higher than in the N-deficient ones, presumably due to the faster recycling of P with respect to N, but differences between addition intervals were non-significant. All microcosms presented an initial bloom dominated by diatoms. In the post-bloom phase, after depletion of the nutrient in short supply, dinoflagellate abundances were higher and diatom abundances lower in the N-deficient than in the P-deficient microcosms. Within nutrient treatments, the qualitative composition of the phytoplankton assemblages was similar across frequencies and replicates. In contrast, characteristics, such as total phytoplankton biovolume or the abundance of dominant taxa, presented significant variability, presumably due to non-linear interactions, even within replicates. This finding suggests the importance of focussing on assemblages rather than on individual taxa when attempting to derive regularities concerning the response of phytoplankton to environmental factors, Funding for this research was provided by the Institut de Ciències del Mar-CMIMA (CSIC, Spain) and EEC contract no. EV5V-CT92-0215 (MARE project)