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Salt-sensitive crop varieties suffer from oxidative stress as a consequence of osmotic and ionic stresses in plants under salinity stress. This study is aimed at identifying the effects of riboflavin (RIB) application on uplifting rice growth under salinized soil condition. Two-week-old seedlings of IR29 (a salt-sensitive variety) were supplemented with 0.5 μM of RIB, and 50 mM of NaCl was supplied for 2 weeks, inducing salinized soil conditions. The results indicated that RIB pretreatment (RP) seedlings possessed higher plant biomass, and lower electrolyte leakage ration (ELR), hydrogen peroxide (H2O2) and malondialdehyde (MDA) concentrations, higher chlorophyll, magnesium (Mg), and iron (Fe) concentrations in the leaf blades, a higher proline concentration, and a lower Na+ concentration in the leaf blades. To further understand the mechanisms behind the difference in plant growth between the RP and non-RP seedlings, molecular analysis revealed that RP seedlings upregulated OsNHX1 and OsHKT1;5 expressions were observed in the roots of RP seedlings, regulating Na+ uptake through the transpiration stream and reducing Na+ concentration in the leaf blades. Collectively, these results suggest that RP is a potent method for improving plant growth under salinized soil conditions. [ABSTRACT FROM AUTHOR]

Accurate estimation of above-ground biomass (AGB) is a crucial aspect of ecosystem management, particularly in game reserves like the Cradle Nature Reserve. This study utilises 2018 AGB at a 50 m resolution to estimate AGB by integrating RGB drone imagery vegetation indices, normalised digital surface model (nDSM), and field-measured chlorophyll concentrations. Principal Component Analysis (PCA) and stepwise regression were employed to identify significant predictors of AGB. The final model for non-riparian forest area explained 66% (R2 = 0.66), with nDSM and red-blue vegetation index (RBVI) as key predictors. In contrast, the riparian model explained 42% (R2 = 0.42), with chlorophyll content and blue-green vegetation index (BGVI) as significant predictors. Our findings highlight the significant influence of nDSM and chlorophyll content on AGB. Vegetation indices such as the green-blue vegetation index (GBVI), green-red vegetation index (GRBI), and RBVI showed diverse correlations with chlorophyll levels, capturing plant greenness and vitality and directly influencing biomass. Comparative analyses of riparian and non-riparian vegetation models revealed that chlorophyll content and BGVI were significant predictors in riparian zones, reflecting interactions between water availability, nutrient flow, and vegetation health. In non-riparian areas dominated by tall trees, nDSM and RBVI were key predictors, underscoring the importance of plant height and stress indicators. This study underscores the effectiveness of drones in remote sensing applications for forest management. These findings contribute to the growing body of knowledge on drone-based biomass estimation, offering valuable insights for managing and conserving ecosystems such as the Cradle Nature Reserve, thereby providing practical implications for ecosystem management and conservation. [ABSTRACT FROM AUTHOR]

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Accurate estimation of above-ground biomass (AGB) is a crucial aspect of ecosystem management, particularly in game reserves like the Cradle Nature Reserve. This study utilises 2018 AGB at a 50 m resolution to estimate AGB by integrating RGB drone imagery vegetation indices, normalised digital surface model (nDSM), and field-measured chlorophyll concentrations. Principal Component Analysis (PCA) and stepwise regression were employed to identify significant predictors of AGB. The final model for non-riparian forest area explained 66% (R2 = 0.66), with nDSM and red-blue vegetation index (RBVI) as key predictors. In contrast, the riparian model explained 42% (R2 = 0.42), with chlorophyll content and blue-green vegetation index (BGVI) as significant predictors. Our findings highlight the significant influence of nDSM and chlorophyll content on AGB. Vegetation indices such as the green-blue vegetation index (GBVI), green-red vegetation index (GRBI), and RBVI showed diverse correlations with chlorophyll levels, capturing plant greenness and vitality and directly influencing biomass. Comparative analyses of riparian and non-riparian vegetation models revealed that chlorophyll content and BGVI were significant predictors in riparian zones, reflecting interactions between water availability, nutrient flow, and vegetation health. In non-riparian areas dominated by tall trees, nDSM and RBVI were key predictors, underscoring the importance of plant height and stress indicators. This study underscores the effectiveness of drones in remote sensing applications for forest management. These findings contribute to the growing body of knowledge on drone-based biomass estimation, offering valuable insights for managing and conserving ecosystems such as the Cradle Nature Reserve, thereby providing practical implications for ecosystem management and conservation.

The Kuroshio Extension (KE) System exhibits highly energetic mesoscale phenomena, but the impact of mesoscale eddies on marine ecosystems and biogeochemical cycling is not well understood. This study utilizes remote sensing and Argo floats to investigate how eddies modify surface and subsurface chlorophyll-a (Chl-a) concentrations. On average, cyclones (anticyclones) induce positive (negative) surface Chl-a anomalies, particularly in winter. This occurs because cyclones (anticyclones) lift (deepen) isopycnals and nitrate into (out of) the euphotic zone, stimulating (depressing) the growth of phytoplankton. Consequently, cyclones (anticyclones) result in greater (smaller) subsurface Chl-a maximum (SCM), depth-integrated Chl-a, and depth-integrated nitrate. The positive (negative) surface Chl-a anomalies induced by cyclones (anticyclones) are mainly located near (north of) the main axis of the KE. The second and third mode represent monopole Chl-a patterns within eddy centers corresponding to either positive or negative anomalies, depending on the sign of the principal component. Chl-a concentrations in cyclones (anticyclones) above the SCM layer are higher (lower) than the edge values, while those below are lower (higher), regardless of winter variations. The vertical distributions and displacements of Chl-a and SCM depth are associated with eddy pumping. In terms of frequency, negative (positive) Chl-a anomalies account for approximately 26% (18%) of the total cyclones (anticyclones) across all four seasons. The opposite phase suggests that nutrient supply resulting from stratification differences under convective mixing may contribute to negative (positive) Chl-a anomalies in cyclone (anticyclone) cores. Additionally, the opposite phase can also be attributed to eddy stirring, trapping high and low Chl-a, and/or eddy Ekman pumping. Based on OFES outputs, the seasonal variation of nitrate from winter to summer primarily depends on the effect of vertical mixing, indicating that convective mixing processes contribute to an increase (decrease) in nutrients during winter (summer) over the KE. [ABSTRACT FROM AUTHOR]

The Kuroshio Extension (KE) System exhibits highly energetic mesoscale phenomena, but the impact of mesoscale eddies on marine ecosystems and biogeochemical cycling is not well understood. This study utilizes remote sensing and Argo floats to investigate how eddies modify surface and subsurface chlorophyll-a (Chl-a) concentrations. On average, cyclones (anticyclones) induce positive (negative) surface Chl-a anomalies, particularly in winter. This occurs because cyclones (anticyclones) lift (deepen) isopycnals and nitrate into (out of) the euphotic zone, stimulating (depressing) the growth of phytoplankton. Consequently, cyclones (anticyclones) result in greater (smaller) subsurface Chl-a maximum (SCM), depth-integrated Chl-a, and depth-integrated nitrate. The positive (negative) surface Chl-a anomalies induced by cyclones (anticyclones) are mainly located near (north of) the main axis of the KE. The second and third mode represent monopole Chl-a patterns within eddy centers corresponding to either positive or negative anomalies, depending on the sign of the principal component. Chl-a concentrations in cyclones (anticyclones) above the SCM layer are higher (lower) than the edge values, while those below are lower (higher), regardless of winter variations. The vertical distributions and displacements of Chl-a and SCM depth are associated with eddy pumping. In terms of frequency, negative (positive) Chl-a anomalies account for approximately 26% (18%) of the total cyclones (anticyclones) across all four seasons. The opposite phase suggests that nutrient supply resulting from stratification differences under convective mixing may contribute to negative (positive) Chl-a anomalies in cyclone (anticyclone) cores. Additionally, the opposite phase can also be attributed to eddy stirring, trapping high and low Chl-a, and/or eddy Ekman pumping. Based on OFES outputs, the seasonal variation of nitrate from winter to summer primarily depends on the effect of vertical mixing, indicating that convective mixing processes contribute to an increase (decrease) in nutrients during winter (summer) over the KE.

Salinity represents one of the most abiotic stress factors affecting plant growth and production around the world. In this experiment, in vitro multiplication of Musa acuminata has been standardized. The physiological and morphological responses of the crop against salt stress have been identified. To study the effects of salicylic acid (SA) and abscisic acid (ABA) on salt stress in banana (Musa acuminata), the explants were treated with varying SA and ABA concentrations and incubated on MS media having various concentrations (0, 50, 100, 150, 200, 250, 300 mM) of NaCl in vitro; hence, their physiological and morphological responses were identified. Two months after, propagation rate, rise of fresh weight, comparative water content, chlorophyll level and proline accumulations were estimated and examined. The outcomes demonstrated that with developing degrees of NaCl, spread rate, new weight, relative water substance and chlorophyll were intriguingly diminished. Use of SA and ABA assisted with impacts of salt insufficiency on banana recovers in vitro and in vivo condition. This work includes image processing and Internet of Things to screen the plant and to gather the natural factors. [ABSTRACT FROM AUTHOR]

Due to the cloud blocking, the research on the responses of upper ocean to typhoons using satellite data is greatly affected. At present, most of the solutions are based on lower time resolution data or composite satellite data. In this paper, multi-source satellite data were fused by weighted average method and reconstructed through the Data INterpolating Convolutional Auto-Encoder method (DINCAE) and used to investigate daily sea surface responses to typhoons. The root mean squared error (RMSE) between the reconstructed data and the cross-validation data for SST and CHL was only 1.093 °C and 0.7833 mg/m3. Three response patterns were reported over the East China Sea (ECS). The first one was that both SST and CHL have significant changes, the second was that only SST changes a lot, and the third one was only CHL changes significantly after typhoons. Moreover, it was found that, after some typhoons, the SST or CHL had a wide range of changes, but the amount of changes is not large. The different responses were related to the wind speed and moving speed of typhoons. In addition, when two typhoons pass by successively, although the wind speed is low, the sea surface would have significant responses. Further, areas of significant SST drops coincide with negative sea level anomaly (SLA) fields in some typhoon tracks. SST drops to its minimum level 2 days after the arrival of a typhoon and returns to its previous level 15 days after the arrival. CHL keeps increasing until 4 days after the typhoon’s passage, and then drops to its initial level around 10 days after the passage. The responses of SST and CHL decrease with distance, with prominent changes occurring within 100 km of the typhoon’s center.

The detection of vertical heterogeneity in vegetation has attracted an increasing attention as it has a great significance for precise agriculture. The hyperspectral light detection and ranging (LiDAR) (HSL) can obtain the spectral and spatial information simultaneously. However, its ability to monitor the vertical distribution of biochemical parameters in plants has not been fully explored. In this article, the applicability of empirical ratio and normalized spectral indices for HSL channels in chlorophyll (Chl) detection was investigated using three data sets: the PROSPECT-5 synthetic data set, the ANGERS public data set, and an HSL-measured data set. A linear regression model of the best performing index against measured Chl values was constructed so as to build 3-D Chl point clouds of maize. The performance of HSL in Chl detection at the upper and lower layers was also tested based on the selected spectral index. The result showed that the CIred edge index was most compatible with the HSL channels. The estimated Chl concentrations of the upper and lower layers showed the close relationships with HSL measurements ($R^{2} = 0.73$ and 0.91, respectively). The vertical Chl profiles in maize were also presented, indicating that the HSL system has a strong ability to monitor the vertical distribution of maize Chl concentrations. This article provides a basis for the vertical detection of vegetation biochemical parameters directly from HSL measurements. [ABSTRACT FROM AUTHOR]

Since 2007, large-scale blooms have periodically broken out in the Yellow Sea, leading to serious economic and ecological problems in the surrounding coastal environments. Previous studies reported that the blooms originated in the Rudong oceanic area of the southern Yellow Sea and drifted almost 400 km into the Qingdao oceanic area of the northern Yellow Sea. In this study, chlorophyll concentrations, chlorophyll fluorescence, growth rates, and reproductive characteristics of floating Ulva prolifera collected along the Yellow Sea coast were assessed. The results revealed that these four physiological parameters in the Rudong area at the bloom source were considerably higher (2.02 mg/g, 0.68, 28.49% d−1, and 4 × 107, respectively) than in the Qingdao area (0.34 mg/g, 0.31, 5.23% d−1, and 0.67 × 107, respectively). However, the abundance of microscopic propagules of Ulva in the Qingdao area (3980 ind/l) was significantly higher than that in the Rudong area (667 ind/l). These findings help increase our understanding of the formation of the world's largest Ulva macroalgal blooms. [ABSTRACT FROM AUTHOR]

Xiang, X.; Lu, W.; Cui, X.; Li, Z., and Tao, J., 2018. Simulation of remote-sensed chlorophyll concentration with a coupling model based on numerical method and CA-SVM in Bohai Bay, China. In: Wang, D. and Guido-Aldana, P.A. (eds.), Select Proceedings from the 3rd International Conference on Water Resource and Environment (WRE2017). Journal of Coastal Research, Special Issue No. 84, pp. 1–9. Coconut Creek (Florida), ISSN 0749-0208. Due to the high-complexity and non-linearity of the marine ecosystem, the internal functional mechanisms of the system have not been fully recognized. This lack of recognition of ecosystems restricts the use of traditional deterministic, aquatic, and ecological dynamic models based on mechanisms or assumptions. By introducing advanced intelligent algorithm support vector machine (SVM) and space display mode cellular automata (CA) from soft computing, a marine ecological module is constructed by combining SVM with CA. Simulation results such as water level, water depth, and flow velocity of the mechanism-based hydrodynamic modules are imported to the corresponding cell. The cell together with the existing cells and neighboring state, spatial location variables as well as extrinsic factors, exerts a combined effect on the cellular state of the cell soon afterwards, and then the coupling model based on the numerical method and soft computing is constructed. With the remote-sensed chlorophyll concentration data at Bohai Bay as the study object, the root-mean-square error (RMSE) of model simulation results were within the range of 0.042 μg/L to 0.373 μg/L, and the difference of spatial auto-correlation indicators Moran's I was within the range of 0.003 μg/L to 0.176 μg/L. Results indicate that an established coupling model encompasses a proper simulation of the temporal and spatial changing features of the chlorophyll concentration. This study thus integrates the traditional, hydrodynamic numerical module and ecological module based on soft computing methods, providing new means and ideas for simulated marine environment. [ABSTRACT FROM AUTHOR]

Marine ecosystems are under the increasing stress of natural and anthropogenic climate variability and change. Knowledge of the patterns of distribution of chlorophyll concentrations as an indicator of phytoplankton abundance, its spatial and temporal variability, and the processes that control this variability is required to better understand the dynamics of marine populations and their fluctuations, including species of ecological and commercial importance. The Patagonia (PLME), South Brazil (SBLME), Humboldt (HLME), and Pacific Coastal Central America (PCACLME) Large Marine Ecosystems (LMEs) around South and Western Central America support high primary productivity and fisheries catch. During the past few decades, climate change and warming in most ecosystems has become evident, which in combination with variations in production rates could impact the dynamics of marine ecosystems. The goal of this study is to assess the variability and longer-term trends in chlorophyll concentrations in the PLME, SBLME, HLME, and PCACLME, and to discuss implications for higher trophic levels. We use a combination of high-resolution satellite-derived chlorophyll concentration data from SeaWiFS (1997–2006) and MODIS Aqua (2002–2017) to examine spatial and temporal variability and analyze the record-length linear trends in these LMEs (25°N-60°S, 30–120°W). We use monthly composites with 2 × 2 km spatial resolution for the period of overlap between sensors (2002–2006) to compare retrievals and adjust the MODIS Aqua data series at all pixels using linear regressions. We then apply the corrections to the MODIS data and combine the SeaWiFS and adjusted MODIS datasets to generate the longest time series in chlorophyll concentrations to date in the region. Our results revealed significant increases in chlorophyll concentrations in large areas of the PLME (78.23%) and HLME (43.03%) during the last ~20 years, with large potential implications for trophic relationships and the reproductive success of fish. For the mostly subtropical SBLME (26.35%) and tropical PCACLME (13.35%), increasing trends were detected only in relatively small regions, while changes in the PLME and HLME are widespread. Results from this study contribute to a better understanding of the potential effects of environmental change on ecosystem dynamics and provide new tools to assess longer-term trends in satellite chlorophyll concentrations.

Nitric oxide (NO) and salicylic acid (SA) are two important signaling molecules, which could alleviate chlorosis of peanut under iron (Fe) deficiency. Here, we further investigated the mechanism of different combinations of sodium nitroprusside (SNP, a nitric oxide donor) and SA supplying in alleviation Fe deficiency symptoms and selected which is the best combination. Thus, peanut was cultivated in hydroponic culture under iron limiting condition with different combinations of SNP and SA application. After 21 days, Fe deficiency significantly inhibited peanut growth, decreased soluble Fe concentration and chlorophyll contents, and disturbed ionic homeostasis. In addition, the content of reactive oxygen species (ROS) and malondialdehyde (MDA) concentration increased, which led the lipid peroxidation. Application of SNP and SA significantly changed Fe trafficking in cells and organs, which increased Fe uptake from nutrient solution, and transport from root to shoot, enhanced the activity of ferric-chelate reductase (FCR), that increased the available Fe in cell organelles, and the active Fe, chlorophyll contents in leaves. Furthermore, ameliorated the inhibition of calcium (Ca), magnesium (Mg) and zinc (Zn) uptake and promoted plant growth in Fe deficiency. At the same time, it increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) to protect the plasmolemma from peroxidation. Results demonstrated that different combinations of SNP and SA application could alleviate the chlorosis of peanut in Fe deficiency by various mechanisms. Such as increased the available Fe and chlorophyll concentrations in leaves, improved the activities of antioxidant enzymes and modulated the mineral elements balance and so on. Foliar application of SNP and SA is the best to protect leaves while directly adding them into nutrient solution is the best to protect roots. These results also indicated that the effects of SNP and SA supplying together to leaves or roots are better than respectively adding to roots and spraying to leaves. The best combination is foliar application of SNP and SA. [ABSTRACT FROM PUBLISHER]

Field experiments were conducted in the experimental farm of the Faculty of Agriculture, Kafrelsheikh University, Kafr El-Sheikh, Egypt, during two growing seasons to study the morpho-physiological and biochemical responses of the susceptible barley plants variety Giza 2000, naturally infected with Pyrenophora teres f. sp. teres (the causal agent of barley net blotch disease). Plants were treated with Premis fungicide as seed treatment however, Bleize fungicide, Na salicylate, Na phosphate, Na carbonate, Tannic acid, Oxalic acid, hydrogen peroxide (H2O2), and benzothiadiazole (BTH) compounds used as foliar application. Dis ease severity (%) was significantly decreased as a result of using all treatments, except oxalic acid, in which exhibited less reduction as compared with the control. Disease symptoms were significantly decreased due to all treatments as compared with control treatment. The endogenous reactive oxygen species (ROS) such as superoxide (O2.-) and H2O2 were significantly accumulated early after the natural infection and in a parallel, activities of antioxidant enzymes catalase (CAT), peroxidase (POX) and polyphenol oxidase (PPO) were not increased or changed compared with the control at early same time. Accordingly, as a result of early accumulation of ROS, later on the activities of antioxidant enzymes were increased significantly compared with the control. High accumulation of ROS levels early after infection could show a central role in killing or inhibiting the fungus as well as perhaps immunizing plants against disease symptoms by increasing the enzyme activities. The tested treatments were effective s o that the chlorophyll a and b concentrations were increased compared with control plants. Consequently, yield character values were increased significantly compared with control treatment. Tested non-traditional treatments seem promising and could be used as an alternate and competitive to fungicides under field conditions. [ABSTRACT FROM AUTHOR]

A greenhouse hydroponic experiment was performed to evaluate how peanut seedlings ( Arachis hypogaea L.) responded to iron (Fe) deficiency stress in the presence of sodium nitroprusside (SNP), a nitric oxide (NO) donor. The results showed that Fe deficiency inhibited peanut plant growth, decreased chlorophyll and active Fe concentrations, and dramatically disturbed ion balance. The addition of 50, 100, 250, and 500 µM SNP, significantly promoted the absorption of Fe in the cell wall, cell organelles, and soluble fractions, increased the concentrations of active Fe and chlorophyll in peanut plants, and alleviated the excess absorption of manganese (Mn) and copper (Cu) induced by Fe deficiency. In addition, SNP also significantly increased the activities of superoxide dismutase, peroxidase, and catalase, which is beneficial to inhibit the accumulation of malondialdehyde and reactive oxygen species. Addition of 250 µM SNP had the most significant alleviating effect against Fe-deficiency stress, and after 15 days of treatment, the plants with the 250 µM SNP treatment achieved comparable NO levels with those grown under optimal nutrition conditions. However, the effects of SNP were reversed by addition of hemoglobin (Hb, a NO scavenger). These results suggest that NO released from SNP decomposition was responsible for the effect of SNP-induced alleviation on Fe deficiency. [ABSTRACT FROM AUTHOR]

A multi-sensor satellite approach based on ocean colour, sunglint and Synthetic Aperture Radar imagery is used to study the impact of interacting internal tidal (IT) waves on near-surface chlorophyll-a distribution, in the central Bay of Biscay. Satellite imagery was initially used to characterize the internal solitary wave (ISW) field in the study area, where the “local generation mechanism” was found to be associated with two distinct regions of enhanced barotropic tidal forcing. IT beams formed at the French shelf-break, and generated from critical bathymetry in the vicinities of one of these regions, were found to be consistent with “locally generated” ISWs. Representative case studies illustrate the existence of two different axes of IT propagation originating from the French shelf-break, which intersect close to 46°N, − 7°E, where strong IT interaction has been previously identified. Evidence of constructive interference between large IT waves is then presented and shown to be consistent with enhanced levels of chlorophyll-a concentration detected by means of ocean colour satellite sensors. Finally, the results obtained from satellite climatological mean chlorophyll-a concentration from late summer (i.e. September, when ITs and ISWs can meet ideal propagation conditions) suggest that elevated IT activity plays a significant role in phytoplankton vertical distribution, and therefore influences the late summer ecology in the central Bay of Biscay. [ABSTRACT FROM AUTHOR]

The effects of salicylic acid (SA) on alleviating chlorosis induced by iron (Fe) deficiency in peanut seedlings ( Arachis hypogaea L.) were studied by investigating the symptoms, plant growth, chlorophyll concentrations, soluble Fe concentration, Fe distribution in subcellular, and antioxidant enzymes. Fe deficiency caused serious chlorosis and inhibited growth of peanut seedlings, and dramatically decreased the soluble Fe concentration and chlorophyll concentration. Furthermore, ion balance was disturbed. The addition of 50, 100, and 250 μM SA significantly increased the absorption of Fe from the cell wall to cell organelles and the soluble fraction, enhanced the Fe concentration in cell organelles, Fe activation and chlorophyll concentrations in leaves, ameliorated the inhibition of Ca, Mg, and Zn absorption induced by Fe deficiency, alleviated the chlorosis induced by Fe deficiency and promoted plant growth. The accumulation of reactive oxygen species (ROS) is dramatically increased in peanut seedlings exposed to Fe deficiency, and resulted in lipid peroxidation, which was indicated by accumulation of malondialdehyde (MDA). The application of 50, 100, and 250 μM SA significantly decreased the level of ROS and MDA concentrations, and significantly increased the activities of superoxide dismutase, peroxidase, and catalase in peanut seedlings exposed to Fe deficiency. The addition of 100 μM SA had the best effect on alleviating chlorosis induced by Fe deficiency, whereas the addition of 500 μM SA had no significant effect under Fe deficiency. [ABSTRACT FROM AUTHOR]

Abstract: A multi-sensor satellite approach based on ocean colour, sunglint and Synthetic Aperture Radar imagery is used to study the impact of interacting internal tidal (IT) waves on near-surface chlorophyll-a distribution, in the central Bay of Biscay. Satellite imagery was initially used to characterize the internal solitary wave (ISW) field in the study area, where the “local generation mechanism” was found to be associated with two distinct regions of enhanced barotropic tidal forcing. IT beams formed at the French shelf-break, and generated from critical bathymetry in the vicinities of one of these regions, were found to be consistent with “locally generated” ISWs. Representative case studies illustrate the existence of two different axes of IT propagation originating from the French shelf-break, which intersect close to 46°N, −7°E, where strong IT interaction has been previously identified. Evidence of constructive interference between large IT waves is then presented and shown to be consistent with enhanced levels of chlorophyll-a concentration detected by means of ocean colour satellite sensors. Finally, the results obtained from satellite climatological mean chlorophyll-a concentration from late summer (i.e. September, when ITs and ISWs can meet ideal propagation conditions) suggest that elevated IT activity plays a significant role in phytoplankton vertical distribution, and therefore influences the late summer ecology in the central Bay of Biscay. [Copyright &y& Elsevier]

Ecosystem models, used mainly in studying the interactions between different trophic levels, can also be used for ocean circulation model skill assessment, with the help of satellite ocean color data. This paper presents how the use of a simple NPZ primary productivity ecosystem model, coupled to a hydrodynamical model, can help assessing the skill of the physical ocean model in depicting realistically the prevailing mesoscale features of the upper layers of the Gulf of Mexico. Results indicate that the physical model effectively reproduces the mesoscale features of circulation underlying the resulting chlorophyll concentrations, especially when circulation fronts exist. [ABSTRACT FROM AUTHOR]

The relationships between water quality and the phytoplankton community within Lake Loskop were studied during the late summer and autumn of 2008 to evaluate the impacts of acid mine drainage and high nutrient concentrations. The higher concentrations of metal ions and sulphate had adverse effects on certain phytoplankton species in the inflowing riverine zone of Lake Loskop, in comparison to the reference site in the lacustrine zone of the lake, which was dominated by the larger and slower growing late summer species of Coelastrum reticulum Nägeli, Straurastrum anatinum Meyen ex Ralfs and Ceratium hirundinella Müller. The high nutrient concentrations (nitrogen: 17mgl−1 and orthophosphate: 0.7mgl−1) during the mid-summer peak of the rainy season were associated with the development of a bloom of the cyanobacterium Microcystis. Water quality data associated with the development of the Microcystis bloom suggest that the aquatic system of Lake Loskop has now entered an alternate, hypertrophic regime. This change overshadowed the adverse effects of high concentrations of heavy metal ions and low pH. Throughout this study, the reference site in the lacustrine zone of Lake Loskop had lower concentrations of metal ions and sulphate, and higher pH values. The response of phytoplankton bioassays on integrated water samples from the different sampling sites did provide potential answers to the reasons for the absence of the algal group Chlorophyceae in the phytoplankton community structure in the riverine zone of the lake. [Copyright &y& Elsevier]