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Dynamic hydrographic and water-quality variations in the northwestern Arabian Gulf, a sinking zone of reverse estuarine circulation Full text
2022
Yamamoto, Takahiro | Madhusoodhanan, Rakhesh | Al-Said, Turki | Ahmed, Ayaz | Fernandes, Loreta | Nithyanandan, Manickam | Thuslim, Fathima | Alghunaim, Aws | Al-Zekri, Waleed | Naqvi, S. Wajih A. | Al-Yamani, Faiza
Continuous measurements of hydrographic, hydrodynamic, and water quality showed marked diurnal, tidal, and seasonal variabilities in Kuwait Bay, a stressed coastal system in the northwestern Arabian/Persian Gulf. Advection of water masses and seasonality in vertical mixing regulated the Bay's hydrographic and water quality properties. Intensive stratification in summer had substantial implications on the Bay environment. Kuwait Bay constantly exports dense bottom water laden with dissolved inorganic nutrients and organic matter to the central basin of the Gulf. The export was largest in August under strong water column stratification. These in-situ findings agreed well with earlier studies that corroborated Kuwait Bay as an important area where the phenomenon of reverse estuarine circulation originates in the Gulf. Thus, Kuwait Bay is a significant source of nutrients and organic matter to the Gulf Deep Water that flows into the core of the oxygen minimum zone in the northwestern Indian Ocean.
Show more [+] Less [-]Surge in the jellyfish population of a tropical monsoonal estuary: A boon or bane to its plankton community dynamics? Full text
2022
Vineetha, G. | Kripa, V. | Karati, Kusum Komal | Madhu, N.V. | Anil, | Vishnu Nair, M.S.
Recurrent jellyfish blooms and their impacts on ecosystem deliverables of coastal habitats have become a major ecological concern. In view of this, repercussions of a surge in the jellyfish population on the plankton community were studied in Cochin estuary (CE), the largest tropical estuary along the southwest coast of India. Evaluation of hydrographic attributes and plankton community of the CE during early and late pre-monsoon revealed a marked disparity in its hydrography which favoured an increase in jellyfish abundances during late pre-monsoon, eliciting distinct impacts on the plankton community. The escalation in the jellyfish abundance and their subsequent predation on the crustacean plankton released the phytoplankton community from the grazing pressure resulting in a trophic cascade in the planktonic food web. The indiscriminate feeding of jellyfishes on the ichthyoplankton, decapod larvae, and Copepoda, the primary diet component of forage fishes evoked a potent threat to the fishery potential of CE.
Show more [+] Less [-]Invasive species fouling Perna perna (Bivalvia: Mytilidae) mussel farms Full text
2022
Lins, Daniel M. | Rocha, Rosana M.
Invasive, fouling species increase management costs and reduce mussel growth, which jeopardizes mariculture. We studied the distribution of eight invasive species in Santa Catarina, the leading mussel producer in Brazil. Our goals were to determine their spatial distribution and prevalence on farm structures (buoys, long lines, and mussel socks), as well as understand the relevance of propagule pressure (recruitment), port distance, and area of the farm in this distribution. Although present in all sites, adult and recruits distribution were spatially restricted, showing that species might have a metapopulation structure. The most prevalent species were the ascidian Styela plicata, the barnacle Megabalanus coccopoma, the bryozoan Schizoporella errata, and the polychaete Branchiomma luctuosum. Recruitment was the main driver of three species distribution while distance to port explained only one species distribution. Based on those results, we discuss policy options, management, and regulation enforcement, that can be used in the mussel aquaculture elsewhere.
Show more [+] Less [-]A novel deep learning method for marine oil spill detection from satellite synthetic aperture radar imagery Full text
2022
Huang, Xudong | Zhang, Biao | Perrie, William | Lu, Yingcheng | Wang, Chen
Oil spill discharges from operational maritime activities like ships, oil rigs and other structures, leaking pipelines, as well as natural hydrocarbon seepage pose serious threats to marine ecosystems and fisheries. Satellite synthetic aperture radar (SAR) is a unique microwave instrument for marine oil spill monitoring, as it is not dependent on weather or sunlight conditions. Existing SAR oil spill detection approaches are limited by algorithm complexity, imbalanced data sets, uncertainties in selecting optimal features, and relatively slow detection speed. To overcome these restrictions, a fast and effective SAR oil spill detection method is presented, based a novel deep learning model, named the Faster Region-based Convolutional Neural Network (Faster R-CNN). This approach is capable of achieving fast end-to-end oil spill detection with reasonable accuracy. A large data set consisting of 15,774 labeled oil spill samples derived from 1786C-band Sentinel-1 and RADARSAT-2 vertical polarization SAR images is used to train, validate and test the Faster R-CNN model. Our experimental results show that the proposed method exhibits good performance for detection of oil spills with wide swath SAR imagery. The Precision and Recall metrics are 89.23% and 89.14%, respectively. The average Precision is 92.56%. The effects of environmental conditions and sensor parameters on oil spill detection are analyzed. The expected detection results are obtained when wind speeds and incidence angles are between 3 m/s and 10 m/s, and 21° and 45°, respectively. Furthermore, the computer runtime for oil spill detection is less than 0.05 s for each full SAR image, using a workstation with NVIDIA GeForce RTX 3090 GPU. This suggests that the present approach has potential for applications that require fast oil spill detection from spaceborne SAR images.
Show more [+] Less [-]Nutrient thresholds to protect water quality, coral reefs, and nearshore fisheries Full text
2022
Houk, Peter | Castro, Fran | McInnis, Andrew | Rucinski, Michael | Starsinic, Christy | Concepcion, Teddy | Manglona, Storm | Salas Russo, Edwin
A ridge-to-reef framework was developed for 26 watersheds around Guam. Dissolved inorganic nitrogen (DIN) data were collected for one year at the base of streams while coral and fish surveys were conducted on adjacent reefs. Two independent analyses revealed a similar 0.10 mg/l DIN threshold beyond which negative impacts to water quality and coral reefs existed. The influence of DIN was next partitioned with respect to a second primary stressor, fishing pressure. While coral diversity was negatively influenced by DIN, the cover of some stress-tolerant corals increased, such as Porites rus, making coral cover alone a poor indicator of watershed pollution. Less intuitive, DIN predicted increased food-fish biomass that was accounted for by generalist herbivores/detritivores, representing homogenized assemblages, while fishing pressure reduced biomass. Our DIN thresholds resonated with a similar study in American Samoa suggesting broader guidance for water quality legislation may be emerging.
Show more [+] Less [-]Does marine environmental research meet the challenges of marine pollution induced by the COVID-19 pandemic? Comparison analysis before and during the pandemic based on bibliometrics Full text
2022
Wang, Qiang | Zhang, Min | Li, Rongrong | Jiang, Xue-ting
The outbreak of the COVID-19 pandemic has brought enormous challenges to the global marine environment. Various responses to the COVID-19 pandemic have led to increased marine pollution. Has the COVID-19 pandemic affected marine pollution research? This work comprehensively reviewed marine pollution publications in the Web of Science database before and during the COVID-19 pandemic. Results show that the COVID-19 outbreak has influenced the marine pollution research by: (i) increasing the number of publications; (ii) reshaping different countries' roles in marine pollution research; (iii) altering the hotspots of marine pollution research. The ranking of countries with high productivity in the marine pollution research field changed, and developed economies are the dominant players both before and after the outbreak of the COVID-19 pandemic in this field. Other high-productivity countries, with the exception of China, have higher international cooperation rates in marine pollution research than those before the pandemic. Microplastic pollution has been the biggest challenge of marine pollution and has been aexplored in greater depth during the COVID-19 pandemic. Furthermore, the mining results of marine pollution publications show the mitigation of plastic pollution in the marine environment remains the main content requires future research. Finally, this paper puts forward corresponding suggestions for the reference of researchers and practitioners to improve the global ability to respond to the challenges posed by the pandemic to the marine environment.
Show more [+] Less [-]Future microplastics in the Black Sea: River exports and reduction options for zero pollution Full text
2022
Strokal, Vita | Kuiper, Eke J. | Bak, Mirjam P. | Vriend, Paul | Wang, Mengru | van Wijnen, Jikke | Strokal, Maryna
Future microplastics in the Black Sea: River exports and reduction options for zero pollution Full text
2022
Strokal, Vita | Kuiper, Eke J. | Bak, Mirjam P. | Vriend, Paul | Wang, Mengru | van Wijnen, Jikke | Strokal, Maryna
The Black Sea receives increasing amounts of microplastics from rivers. In this study, we explore options to reduce future river export of microplastics to the Black Sea. We develop five scenarios with different reduction options and implement them to a Model to Assess River Inputs of pollutaNts to seA (MARINA-Global) for 107 sub-basins. Today, European rivers draining into the Black Sea export over half of the total microplastics. In 2050, Asian rivers draining into the sea will be responsible for 34–46% of microplastic pollution. Implemented advanced treatment will reduce point-source pollution. Reduced consumption or more collection of plastics will reduce 40% of microplastics in the sea by 2050. In the optimistic future, sea pollution is 84% lower than today when the abovementioned reduction options are combined. Reduction options affect the share of pollution sources. Our insights could support environmental policies for a zero pollution future of the Black Sea.
Show more [+] Less [-]Future microplastics in the Black Sea : River exports and reduction options for zero pollution Full text
2022
Strokal, Vita | Kuiper, Eke J. | Bak, Mirjam P. | Vriend, Paul | Wang, Mengru | van Wijnen, Jikke | Strokal, Maryna
The Black Sea receives increasing amounts of microplastics from rivers. In this study, we explore options to reduce future river export of microplastics to the Black Sea. We develop five scenarios with different reduction options and implement them to a Model to Assess River Inputs of pollutaNts to seA (MARINA-Global) for 107 sub-basins. Today, European rivers draining into the Black Sea export over half of the total microplastics. In 2050, Asian rivers draining into the sea will be responsible for 34–46% of microplastic pollution. Implemented advanced treatment will reduce point-source pollution. Reduced consumption or more collection of plastics will reduce 40% of microplastics in the sea by 2050. In the optimistic future, sea pollution is 84% lower than today when the abovementioned reduction options are combined. Reduction options affect the share of pollution sources. Our insights could support environmental policies for a zero pollution future of the Black Sea.
Show more [+] Less [-]Evaluation of heavy metals contamination and pollution indices levels in surface sediments of the Bizerte coastal line, Tunisia Full text
2022
Aydi, Abdelwaheb | Ghannem, Samir | Nasri, Ahmed | Hessine, Rania | Mezni, Amine
Heavy metal concentrations in surface sediments collected from 17 stations samples in Bizerte coastal line were determined in order to evaluate the contamination status in the region. Heavy metal concentrations (mg/kg) of Bizerte coast line followed the decreasing trend of Fe > Pb > Zn > Mn > Cu > Cr > Ni > Co > Cd. The pollution degree of the surface sediment collected from 17 samples station in Bizerte coast line by heavy metals was evaluated on the basis of pollution indices (EF, Igeo, CF, PLI and CD). Results of Igeo, EF, CF, PLI and DC demonstrated that pollution levels of Pb and Cd were moderate, which should require more attentiveness as main pollution factors. However, no pollution was found for Zn, Cu, Ni, Cr, Co and Mn. Hierarchical cluster analysis was used to identify the influence of anthropogenic activities on the surface sediment.
Show more [+] Less [-]Detecting long temporal trends of photosystem II herbicides (PSII) in the Great Barrier Reef lagoon Full text
2022
Taucare, Grechel | Bignert, Anders | Kaserzon, Sarit | Thái Phong, | Mann, Reinier M. | Gallen, Christie | Mueller, Jochen
The Marine Monitoring Program (MMP) was established in 2005 to monitor the inshore health of the Great Barrier Reef (GBR) and evaluate progress towards water quality objectives in Reef Water Quality Improvement Plans. The MMP provides information on the magnitude and spatial extent of pesticide contamination, reports on temporal variability, and provides a risk assessment for the biota in the GBR lagoon. However, long-term trends in pesticide contamination of inshore marine waters over the entire monitoring period (2005–2018) have not been assessed. We used up to 14 years of monitoring data for five PSII herbicides (ametryn, atrazine, diuron, tebuthiuron, and hexazinone) to conduct temporal trend analyses at 11 inshore monitoring sites. The trend analyses suggested increasing significant trends (p < 0.05) for the five PSII herbicides concentrations at several monitoring sites. Power analysis indicated that monitoring sites with over 10 years of monitoring data had convincing results with 80% power.
Show more [+] Less [-]Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community Full text
2022
Baden, S. (Susanne) | Fredriksen, Stein | Christie, Hartvig | Eriander, Louise | Gustafsson, Camilla | Holmer, Marianne | Olesen, Birgit | Thormar, Jonas | Boström, Christoffer
Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community Full text
2022
Baden, S. (Susanne) | Fredriksen, Stein | Christie, Hartvig | Eriander, Louise | Gustafsson, Camilla | Holmer, Marianne | Olesen, Birgit | Thormar, Jonas | Boström, Christoffer
We conducted a short-term field sampling complemented with time integrating stable isotope analysis to holistically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya.
Show more [+] Less [-]Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community Full text
2022
Baden, Susanne | Fredriksen, Stein | Christie, Hartvig C | Eriander, Louise | Gustafsson, Camilla | Holmer, Marianne | Olesen, Birgit | Thormar, Jonas | Boström, Christoffer
We conducted a short-term field sampling complemented with time integrating stable isotope analysis to holistically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya.
Show more [+] Less [-]Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community Full text
2022
Baden, Susanne | Fredriksen, Stein | Christie, Hartvig C | Eriander, Louise | Gustafsson, Camilla | Holmer, Marianne | Olesen, Birgit | Thormar, Jonas | Boström, Christoffer
We conducted a short-term field sampling complemented with time integrating stable isotope analysis to holistically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya. | publishedVersion
Show more [+] Less [-]Effects of depth and overgrowth of ephemeral macroalgae on a remote subtidal NE Atlantic eelgrass (Zostera marina) community Full text
2022
Baden, Susanne | Fredriksen, Stein | Christie, Hartvig C | Eriander, Louise | Gustafsson, Camilla | Holmer, Marianne | Olesen, Birgit | Thormar, Jonas | Boström, Christoffer
We conducted a short-term field sampling complemented with time integrating stable isotope analysis to holistically investigate status and ecological interactions in a remote NE Atlantic Zostera marina meadow. We found high nutrient water concentrations, large biomass of fast-growing, ephemeral macroalgae, low abundance, and biodiversity of epifauna and a food web with thornback ray (Raja clavata) as intermediate and cod (Gadus morhua) as top predator. We observed no variation with increasing depth (3.5–11 m) except for decreasing shoot density and biomass of Zostera and macroalgae. Our results indicate that the Finnøya Zostera ecosystem is eutrophicated. During the past three to four decades, nutrients from aquaculture have steadily increased to reach 75% of anthropogenic input while the coastal top predator cod has decreased by 50%. We conclude that bottom-up regulation is a predominant driver of change since top-down regulation is generally weak in low density and exposed Zostera ecosystems such as Finnøya. | publishedVersion
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