Most pollutants found in rivers come from the discharge of raw sewage from both point and nonpoint sources. So, monitoring the pollution levels in surface water sources is essential. River pollution monitoring is a real challenge. Using remote sensing, precise outcomes can be achieved with the help of the selection of the right combination of satellite images and algorithms. Generally, established available algorithms are site-specific, indicating that they may not work at all areas on Earth's surface due to differences in altitude, cloud cover, and sun glint. The present work determined Chlorophyll-a concentrations in the Tapi River at various locations using Landsat-8 satellite images and Acolite software from 2017 to 2021 Period. The outcomes reveal that applying the dark spectrum fitting with sun glint correction when processing Landsat-8 satellite images is needed. In the present study, water quality results were obtained very precisely for the months of January, February, November, and December after processing and analysing satellite images. Due to factors such as sun glare, cloud cover, cloud shadow, and haze, the desired effect could not be achieved in the remaining months of the study period. This research provides a solid foundation for estimating the impact of eutrophication in the water body by estimating chlorophyll-a concentration from satellite images.

peer reviewed | The northwestern shelf of the Black Sea has been affected by eutrophication and bottom hypoxia since the sixties. Consequently, the macrozoobenthos has suffered a well-established decline in biodiversity. However, the nature of the current benthic communities remains questionable. From 1995 to 2017, we compiled species and abiotic data for 138 sites over the shelf. Through an appropriate multivariate analytical approach, we identified benthic community changes solely due to organic pollution variations. Our results show signs of recovery with an increase in biodiversity and proportion of species vulnerable to organic enrichment. These changes were related to a decrease in riverine loads and subsequent eutrophication. However, some long-lived species typical of the area still did not exhibit noticeable recovery, which suggests that either the recovery process has not yet been achieved or some environmental conditions are still not met to warrant a sea floor ecosystem state substantially healthy. | 14. Life below water

peer reviewed | The northwestern shelf of the Black Sea has been affected by eutrophication and bottom hypoxia since the sixties. Consequently, the macrozoobenthos has suffered a well-established decline in biodiversity. However, the nature of the current benthic communities remains questionable. From 1995 to 2017, we compiled species and abiotic data for 138 sites over the shelf. Through an appropriate multivariate analytical approach, we identified benthic community changes solely due to organic pollution variations. Our results show signs of recovery with an increase in biodiversity and proportion of species vulnerable to organic enrichment. These changes were related to a decrease in riverine loads and subsequent eutrophication. However, some long-lived species typical of the area still did not exhibit noticeable recovery, which suggests that either the recovery process has not yet been achieved or some environmental conditions are still not met to warrant a sea floor ecosystem state substantially healthy. | 14. Life below water

Green tides occurrence has increased in coral reefs, yet few reference values have been documented to support bloom management in these ecosystems. Here, we took advantage of recent Ulva green tides that occurred in New Caledonia to (i) identify the elements limiting the growth of Ulva spp. during these blooms; and (ii) validate the use of isotopic markers for identifying sources of nutrients that generated blooms. N/P ratios highlighted a stronger limitation of algae by phosphorus than by nitrogen on sites under oceanic influence, while the proportions of N and P were optimal for algal growth at sites where green tides occurred. Macroalgae highly exposed to sewage water was characterized by higher δ15N than macroalgae collected in areas exposed to synthetic inorganic fertilizers. From these results, we established a new set of threshold values for using δ15N in Ulva species as an indicator of nitrogen source type in coral reefs.