Estuarine and Coastal Ecosystems: Anthropogenic Degradation and the Impacts of Restoration Efforts

A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Marine Environmental Science".

Deadline for manuscript submissions: 20 July 2025 | Viewed by 6670

Special Issue Editors


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Guest Editor
Florida Institute of Technology, Melbourne, FL, USA
Interests: marine ecology; larval ecology; water column ecology;harmful algal blooms; invasive species; planktonic predator-prey interactions; metamorphosis; phenotypic plasticity; larval transport; settlement
Department of Ocean Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, USA
Interests: cycling of trace metals;nutrients in coastal estuaries; organic-rich sediments; benthic food webs

Special Issue Information

Dear Colleagues,

Coastal zones and estuaries are among the most attractive regions for homes, commerce, and industry, hosting 40% of the world’s population. These regions also have diverse and productive habitats and ecosystems, sources of valuable natural resources. Climate change, urbanization, eutrophication, and other anthropogenic effects are global problems that threaten to undermine these natural systems' ecological and economic value. This Special Issue seeks to document the system status, pollution sources, climate impacts, loss of biodiversity, as well as restoration and mitigation techniques, and ecosystem outcomes for estuaries and coastal zones. It will include the following:

  1. Documenting existing and historical environmental, ecological, and biological conditions;
  2. Examining sources of degradation and impacts on water quality, sediment quality, or biology;
  3. Modeling future outcomes of anthropogenic degradation;
  4. Testing experimental restoration and mitigation techniques and outcomes;
  5. Documenting or modeling the effects of climate change, acidification, or sea level rise;
  6. Reporting on the occurrences, causes, and impacts of harmful algal blooms;
  7. Explaining and analyzing hypoxia, fish kills, and other mass mortality events;
  8. Evaluating the status, decline, or restoration of water column and benthic ecosystems;
  9. Appraising the population biology of estuarine and coastal species, including fisheries species;
  10. Measuring the occurrence and effects of exotic introductions and invasive species;
  11. Studying sustainability in coastal and estuarine ecosystems.

Original research articles and reviews are welcome. Research approaches may include, but are not limited to, empirical, observational, in situ, laboratory, and modeling studies.

Prof. Dr. Kevin B. Johnson
Dr. Austin Fox
Guest Editors

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Keywords

  • pollution sources
  • climate impacts
  • loss of biodiversity
  • restoration and mitigation techniques
  • ecosystem outcomes for estuaries and coastal zones

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Published Papers (5 papers)

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Research

23 pages, 3249 KiB  
Article
Benthic Mollusk Biodiversity Correlates with Polluted Sediment Conditions in a Shallow Subtropical Estuary
by Rachael H. Stark and Kevin B. Johnson
J. Mar. Sci. Eng. 2025, 13(1), 13; https://doi.org/10.3390/jmse13010013 - 26 Dec 2024
Viewed by 855
Abstract
To quantify the ecological impacts of organic sediments and environmental dredging, benthic mollusks were chosen as bioindicators of environmental change, measured as sediment organic content and associated parameters. Data on species richness, ecological diversity (which was measured as biodiversity), and abundances were collected [...] Read more.
To quantify the ecological impacts of organic sediments and environmental dredging, benthic mollusks were chosen as bioindicators of environmental change, measured as sediment organic content and associated parameters. Data on species richness, ecological diversity (which was measured as biodiversity), and abundances were collected alongside sediment and near-bottom water quality data before, during, and after environmental dredging. Organic sediment content was found to have an inverse logarithmic relationship with benthic mollusk biodiversity, species richness, and abundance. Post hoc analyses found that percent dissolved oxygen, which correlates with sediment organic content, was responsible for 29.31–34.12% of the benthic mollusk community variation. Sediments with lower organic content had higher biodiversity (organism densities up to 1 organism m−2), abundance (over 2.0 × 105 organisms m−2), and species richness (organism densities up to 4 organisms m−2). In comparison, sediments with higher organic content had low biodiversity (organism densities 0–1 organisms m−2), abundance (as low as 0 organisms m−2), and species richness (organism densities as low as 0 organisms m−2). Full article
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19 pages, 3739 KiB  
Article
Standard Descriptors and Selected Biomarkers in Assessment of Posidonia oceanica (L.) Delile Environmental Response
by Željka Vidaković-Cifrek, Mirta Tkalec, Tatjana Bakran-Petricioli, Jasna Dolenc Koce, Jelena Bobetić, Adam Cvrtila, Ana Grbčić, Janja Maroević, Nina Mikec, Jelena Samac and Mateja Smiljanec
J. Mar. Sci. Eng. 2024, 12(11), 2072; https://doi.org/10.3390/jmse12112072 - 16 Nov 2024
Cited by 1 | Viewed by 1017
Abstract
Endemic Mediterranean seagrass Posidonia oceanica is highly endangered today as it lives in a narrow infralittoral zone intensely exposed to human impact. P. oceanica beds are especially endangered in the Adriatic Sea as the central and northern Adriatic could be considered as a [...] Read more.
Endemic Mediterranean seagrass Posidonia oceanica is highly endangered today as it lives in a narrow infralittoral zone intensely exposed to human impact. P. oceanica beds are especially endangered in the Adriatic Sea as the central and northern Adriatic could be considered as a naturally suboptimal area for P. oceanica growth. In this research, we used some standard descriptors of Posidonia meadows at different locations and depths and determined the biochemical parameters (phenolic compounds, photosynthetic pigments, and enzyme activities) in its leaves in order to find possible correlations among the measured parameters and environmental conditions. Photosynthetic pigments were shown to be sensitive biomarkers in the assessment of P. oceanica response to different light conditions, but more research is needed to elucidate the impact of other environmental factors. Overall, the results of this research show that the studied parameters are good bioindicators of a meadow’s environmental state, but it is necessary to analyze a number of diverse indicators together to properly characterize the state of a particular P. oceanica meadow. This approach would be very useful in the determination of P. oceanica conservation status, which is the first step towards improving monitoring protocols and implementing appropriate conservation measures. Full article
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17 pages, 5385 KiB  
Article
Patterns in Anthropogenic Nitrogen and Water Quality Leading to Phytoplankton Blooms in Urban Estuaries
by Richard C. Dugdale, Alexander E. Parker and Frances P. Wilkerson
J. Mar. Sci. Eng. 2024, 12(11), 2029; https://doi.org/10.3390/jmse12112029 - 9 Nov 2024
Viewed by 1173
Abstract
The San Francisco Estuary (SFE) ecosystem receives anthropogenic ammonium (NH4) from agricultural runoff and sewage treatment plants and has low chlorophyll levels. As observed in other aquatic systems, NH4 at concentrations < 4 µmol/L inhibits nitrate (NO3) uptake [...] Read more.
The San Francisco Estuary (SFE) ecosystem receives anthropogenic ammonium (NH4) from agricultural runoff and sewage treatment plants and has low chlorophyll levels. As observed in other aquatic systems, NH4 at concentrations < 4 µmol/L inhibits nitrate (NO3) uptake by phytoplankton and can reduce the frequency with which phytoplankton assimilate all available inorganic nitrogen (i.e., NO3 and NH4); paradoxically, elevated NH4 can reduce the chances of phytoplankton blooms in some high NH4 ecosystems. For blooms to occur, NH4 must first be reduced to non-repressive levels, then NO3 uptake can occur and is accompanied by more rapid carbon (C) uptake and chlorophyll accumulation. The consequence of this sequence is that when NO3 uptake, C uptake, or chlorophyll concentrations are plotted against ambient NH4, a rectangular hyperbola results. Here, these relationships are statistically described for a variety of SFE field data, and their management applications are discussed. These relationships enable ambient NH4 to be used to predict both the likelihood of blooms and to investigate historical changes in productivity when no rate measurements were made. We apply the statistical relationship to a 40-year time series from the SFE during which there was an ecosystem-scale change in the estuarine foodweb with a drastic decline in pelagic fishes (the pelagic organism decline) and suggest that this period aligned with the lowest annual primary production and highest NH4. The relationship may be generalizable to other high-nitrogen, low-growth systems and aid nutrient management decisions, assuming potential limitations are considered. Full article
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15 pages, 3415 KiB  
Article
Glyphosate Herbicide Impacts on the Seagrasses Halodule wrightii and Ruppia maritima from a Subtropical Florida Estuary
by Austin Fox, Hope Leonard, Eugenia Springer and Tyler Provoncha
J. Mar. Sci. Eng. 2024, 12(11), 1941; https://doi.org/10.3390/jmse12111941 - 31 Oct 2024
Viewed by 1054
Abstract
Seagrass meadows are among the most threatened ecosystems on Earth, with losses attributed to increasing coastal populations, degraded water quality and climate change. As coastal communities work to improve water quality, there is increased concern regarding the use of herbicides within the watersheds [...] Read more.
Seagrass meadows are among the most threatened ecosystems on Earth, with losses attributed to increasing coastal populations, degraded water quality and climate change. As coastal communities work to improve water quality, there is increased concern regarding the use of herbicides within the watersheds of these sensitive ecosystems. Glyphosate is the most widely used herbicide on Earth because it is non-selective and lethal to most plants. Also, the targeted amino acid synthesis pathway of glyphosate is not carried out by vertebrates, and it is generally considered one of the safer but effective herbicides on the market. At least partially due to its cost-effectiveness compared to other techniques, including mechanical harvesting, glyphosate use in the aquatic environment has increased in coastal areas to manage aquatic weeds, maintain navigable waterways and mitigate upland flooding. This has prompted concerns regarding potential ecosystem-level impacts. To test the acute toxicity of glyphosate to seagrasses, mesocosm experiments exposed Ruppia maritima and Halodule wrightii to 1 ppm, 100 ppm and 1000 ppm of glyphosate (as glyphosate acid). No significant decrease in leaf chlorophyll a (Chl a) was identified for either species at 1 ppm versus a control; however, significant decreases were observed at higher concentrations. In all except 1000 ppm mesocosms, water column Chl a increased, with a 7-fold increase at 100 ppm. These data demonstrate that at very high glyphosate concentrations, both acute toxicity and light limitation from enhanced algal biomass may have adverse impacts on seagrasses. Despite these observations, no significant adverse impacts attributed to acute toxicity were observed at 1 ppm, which is >1000 times higher than concentrations measured in the Indian River Lagoon system. Overall, herbicide use and associated decaying biomass contribute nutrients to these systems, in contrast to the removal of nutrients when mechanical harvesting is used. Based on our data and calculations, when used at recommended application rates, contributions to eutrophication, degraded water quality and harmful algal blooms were more likely to impact seagrasses than acute toxicity of glyphosate. Full article
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18 pages, 3855 KiB  
Article
The Development of a Floating Mono-Particle “Sun Shield” to Protect Corals from High Irradiance during Bleaching Conditions
by Joel M. P. Scofield, Emma L. Prime, Florita Flores, Andrea Severati, Mathieu Mongin, Elodie Bougeot, Mark E. Baird, Andrew P. Negri and Greg G. Qiao
J. Mar. Sci. Eng. 2024, 12(10), 1809; https://doi.org/10.3390/jmse12101809 - 10 Oct 2024
Cited by 1 | Viewed by 1597
Abstract
Coral bleaching is occurring more frequently as the climate changes, with multiple mass mortality events recently recorded on the Great Barrier Reef. Thermal stress coupled with high irradiance have previously been shown to be primary causes for coral bleaching. Therefore, a reduction in [...] Read more.
Coral bleaching is occurring more frequently as the climate changes, with multiple mass mortality events recently recorded on the Great Barrier Reef. Thermal stress coupled with high irradiance have previously been shown to be primary causes for coral bleaching. Therefore, a reduction in either of these pressures could reduce coral stress and eventual bleaching. Herein, we report the early development of a novel technology capable of reducing the amount of light entering a water body by ~20% in open ocean conditions. This mono-particle “sun shield” consists of an ultra-thin monolayer material and reflective calcium carbonate particles. The monolayer enables spreading of the particles into a thin film across the water surface, with only small amounts of material needed: 7.1 g/m2. A numerical modelling case study of residence times and the build-up of reactive oxygen stress in corals showed that the successful application of a stable film over the Lizard Island reef flat could reduce the reactive oxygen stress to below bleaching levels across approximately 1.5 km2 of reef area. With further development, mono-particle films such as this have the potential to be deployed over at-risk coral reefs at relatively small scales during predicted heatwave conditions, potentially reducing the severity of bleaching on coral reefs. Full article
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