Costal Oceanography

Marine plastic debris floating on the ocean surface is a major environmental problem. However, its distribution in the ocean is poorly mapped, and most of the plastic waste estimated to have entered the ocean from land is unaccounted for. Better understanding of how plastic debris is transported from coastal and marine sources is crucial to quantify and close the global inventory of marine plastics, which in turn represents critical information for mitigation or policy strategies. At the same time, plastic is a unique tracer that provides an opportunity to learn more about the physics and dynamics of our ocean across multiple scales, from the Ekman convergence in basin-scale gyres to individual waves in the surfzone. In this review, we comprehensively discuss what is known about the different processes that govern the transport of floating marine plastic debris in both the open ocean and the coastal zones, based on the published literature and referring to insights from neighbouring fields such as oil spill dispersion, marine safety recovery, plankton connectivity, and others. We discuss how measurements of marine plastics (both in situ and in the laboratory), remote sensing, and numerical simulations can elucidate these processes and their interactions across spatio-temporal scales.

This paper presents a novel initiative for reliable high-resolution forecasts on prevailing sea states at 50 important ports worldwide (Accu-Waves; http://accuwaves.eu/). Its goal is to support safe navigation, unhampered vessel approaching to busy harbored areas, and secure ship maneuvering in ports. Accu-Waves 1 is based on integrated, high-resolution, ocean and coastal modeling that uses data from global scale, open-sea forecasts as boundary conditions. The models' setup, coupling, nesting, calibration, verification, and application are reported herein, concerning areas near and inside globally significant port basins. Thus, we present the automated operational setup of the Accu-Waves service for three-day forecasts at three-hourly intervals.

Sedimentation is a critical threat to coral reefs worldwide. Major land use alteration at steep, highly erodible semi-arid islands accelerates the potential of soil erosion, runoff, and sedimentation stress to nearshore coral reefs during extreme rainfall events. The goal of this study was to assess spatio-temporal variation of sedimentation dynamics across
nearshore coral reefs as a function of land use patterns, weather and oceanographic dynamics, to identify marine ecosystem conservation strategies. Sediment was collected at a distance gradient from shore at Bahia Tamarindo (BTA) and Punta Soldado (PSO) coral reefs at Culebra Island, Puerto Rico. Sediment texture and composition were analyzed by dry sieving and loss-on-ignition techniques, and were contrasted with
environmental variables for the research period (February 2014 to April 2015). Rainfall and oceanographic data were analyzed to address their potential role on affecting sediment distribution with BEST BIO-ENV, RELATE correlation, and linear regression analysis. A significant difference in sedimentation rate was observed by time and distance from
shore (PERMANOVA, p < 0.0100), mostly attributed to higher sediment exposure at reef zones closer to shore due to strong relationships with coastal runoff. Sedimentation rate positively correlated with strong rainfall events (Rho = 0.301, p = 0.0400) associated with storms and rainfall intensity exceeding 15 mm/h. At BTA, sediment deposited were mostly composed of sand, suggesting a potential influence of resuspension produced by waves and swells. In contrast, PSO sediments were mostly composed of silt-clay and terrigenous material, mainly attributed to a deforestation event that occurred at adjacent steep sub-watershed during the study period. Spatial and temporal variation of sedimentation pulses and terrigenous sediment input implies that coral reefs exposure to sediment stress is determined by local land use patterns, weather, and oceanographic dynamics. Comprehensive understanding of sediment dynamics and coastal ecosystem interconnectivity is fundamental to implement integrated and adaptive
management strategies aimed to promote sustainable development at watershed and island wide-scale to fully mitigate terrigenous sediment impact to marine ecosystems. Furthermore, decision-making processes and policy needs to address sedimentation stress in the context of future climate to reduce land-based threats and strengthen coral reef resilience.

This paper quantifies the extent to which Chakaria Sundarbans mangrove has been depleted through human interference using Landsat imagery of 1972 and 2017. The images were corrected for radiometric and atmospheric effects. To improve the classification process, the Chakaria Sundarbans's Landsat 2017 image was pan-sharpened. The earlier image which comprises of the virgin forest was classified into three classes (water, mangrove, wetland) while the later was classified into four classes – waterbody, mangrove, pond scum and saltpan using supervised classification method and support vector machine classifier. Using the statistical bias adjustment, precise area estimates for each land cover class was obtained. The result shows that between 1972 and 2017, Chakaria Sundarbans mangrove forest has reduced by about 87.5% (from 6000.27 to 877.76 hectares). Currently, about 21% of the land is being used for salt mining, 45% for shrimp farming while the water body takes 26%. It is observed that the river has reduced in width; however, water surface area increased by 2%. The bias-adjusted overall classification accuracy yields 95.44% and 94.70% for classified maps of 1972 and 2017, respectively. Evidently, the mangrove has been completely lost to over-exploitation of resources.

The present study distinguishes types of fishing activities. It records the most economically exploited shrimps in the municipality of Lucena, Paraíba, Xiphopenaeus kroyeri (" espigudo "), and Penaeus schmitti (white shrimp). From October 2014 to October 2015, samples containing 700 gr of shrimp were collected at three sites of artisanal fishing. Data on temperature, ammonium, nitrate, nitrite, chlorophyll-a, salinity, pH, and dissolved oxygen were recorded. Two different shrimp species are commercially used in the region, of 2,628 sampled individuals, X. kroyeri predominated, with 1,957 individuals, followed by P. schmitti, with 671 individuals. At localities 1 (in Lucena beach) and 2 (Fagundes beach) both species were present, the X. kroyeri being predominant, but at locality 3 (Costinha beach) only the P. schmitti was recorded. The regional wet season influenced salinity during the months of the year, producing positive and/or negative correlations among species found at each locality depending on what was analyzed. It is relevant to understand the relationship between fishing resources and environmental variables which provide information about fishing dynamics and permits the development of strategies for the maintenance of stocks and fishing areas, as well as permitting the establishment of public regulations for the better preservation and conservation of marine areas and estuaries on which many species depend for the completion of their life cycles.

Thermaikos Gulf, located in the Northwestern Aegean Sea, is a marine ecosystem of major importance, not only environmentally, but also due to the various socioeconomic activities associated with area (Krestenitis et al., 2012). A multi-platform observational study was conducted in summer, autumn and winter 2017 to investigate the current quality state of seawater and seabed. Water and sediment samples were seasonally collected from three sampling stations located at the northern part of Thermaikos Gulf: two stations at the outfall areas of the Thessaloniki's Wastewater Treatment Plants (WTP) and one very close to the city's seafront. The measurements include the physical (CTD), chemical and biological characteristics of the water column (phytoplankton and protozooplankton community) and seabed (macro-invertebrates). Satellite data were also used to discuss the in situ findings. Very large temperature and chl-a differences were observed between Thessaloniki (inner) and Aggelohori (outer) Gulf in December. Very high surface concentrations of phosphates and total phosphorus were also measured, especially in Thessaloniki. The phytoplankton biomass was extremely high in the inner Gulf on July after the “dirty” Sea phenomenon and on December when strong Mesodinium rubrum red tide were observed in the inner Gulf. Polychaetes and mollusks prevailed in the sediment fauna. The density of macro-invertebrates was found very increased close to the seafront of Thessaloniki.Significant differences were detected in physical and biochemical characteristics between the inner and outer Gulf. More brackish waters were measured in summer than in fall and winter.