Nutrient sources to coastal waters with coral reefs are not well-characterized. This study documented spatial distributions of nutrients within coastal waters along two developments with coral reefs, and identified nutrient sources through nutrient mixing plots, δ¹⁵N measurements in macroalgal tissue, and NO₃⁻ stable isotope mixing models. Nutrients decreased from fresh groundwaters to offshore waters, with some surface waters higher in concentrations than benthic ones. Conservative and non-conservative mixing between fresh and ocean waters occurred, the latter suggestive of local nutrient sources and biological removal. δ¹⁵N in macroalgal tissue and NO₃⁻ concurred that fresh groundwater, ocean water, and fertilizers were dominant nutrient sources. Benthic salinity and NO₃⁻ + NO₂⁻ concentrations illustrated that submarine groundwater discharge delivered nutrients to reefs in pulses ranging from minutes to days. Information generated from this study is imperative for developing management actions to improve water quality and make coral reefs more resilient to stressors.

The oil spill that reached Brazilian Coast in 2019 was one of the most extensive disasters and its effects on distinct species are still under investigation. This study evaluated the effects of the oil spill on the crab Pachygrapsus transversus in four reef areas in Northeast of Brazil that are also under different levels of chronic anthropogenic impacts. Changes in population aspects were investigated including maturity, sex ratio, and relative growth considering periods before and after the oil spill. An acute decrease in the number of females captured in areas most affected by oil spill was evident and may be associated with the closure of burrows used for protection. Crabs from the most touristic area presented a decrease in the medium size of carapace and maturation compared to crabs from other less visited areas, which highlights the importance of studying the effects of impacts on marine fauna.

Heavy metal pollution on beaches due to enhanced human activities has received attention. This study takes four beaches in China as examples to study the characteristics of heavy metal pollution. The results show that most beach sediments have a certain degree of heavy metal accumulation as a result of human activities, except for the sediments of No. 1 beach. The beaches in order of the degree of pollution were No. 3 beach > Shilaoren beach > No. 2 beach > No. 1 beach. Three of the four studied beaches show contamination with As, Cr, Fe, Ni, Pb and Zn. Sewage outlets are the main sources of these pollutants, but the high levels of Zn and Fe are caused by coal cinder dumping at one beach, and the high levels of Ni are due to the coating of fishing boats at another beach. Heavy metal pollution occurs in areas near pollutant sources or at the high or low tide lines due to waves and tides. Heavy metals also diffuse vertically, resulting in contamination at certain depths. The distribution of heavy metals over ten years showed that most of the pollutants on cape–bay beaches are difficult to diffuse outward, which indicates that a special pollutant management plan needs to be developed for such beaches.

Studies show that a driver of coastal debris is the rate between debris deposition and resuspension; however, the influence of beach zone topography on the distribution of debris remains poorly understood. Using five years of marine debris data collected by the COASST citizen science program, we explored the spatiotemporal trends in debris abundance within two regions of the United States Pacific Northwest and investigated whether higher debris loads are associated with beach zones that have a higher propensity to trap debris. We found that beaches with larger wood zones had higher debris loads, adding to the growing evidence that backshore areas of beaches act as sinks for debris. Higher debris loads were also associated with beaches that had larger wrack zones suggesting that onshore transport from the marine reservoir is a dominant source of debris. This study provides a long-term baseline of marine debris which managers could use to inform source reduction interventions.

In coastal productive zones, phytoplankton activity may influence trace metal speciation and partitioning at short temporal scale. We coupled hourly in situ voltammetry quantification of the lead (Pb), cadmium (Cd), and copper (Cu) potentially bioavailable fractions, using an innovative submersible sensing probe (the TracMetal), to surface water sampling for the quantification of the targeted trace metals in the dissolved <0.2 μm and <0.02 μm fractions, suspended particles, and phytoplankton nets in the Gironde Estuary mouth. The in situ TracMetal monitoring reflected real-time dynamic Cd and Cu regeneration related to algal cells under post-bloom conditions as well as Pb remobilization due to photoreduction of colloids. The potentially bioavailable fraction consisted in 30, 30–50 and <10 % of the total dissolved fraction for Pb, Cd, and Cu, respectively, representing crucial ecotoxicological information. Metal bioconcentration factors using the dynamic fraction concentrations showed levels up to 10⁷ for Cu in phytoplankton.

Nowadays, people have known more about the distribution features on the surface of beaches. However, the understanding on the microplastics (Mps) distribution in the vertical direction on beaches is still lacking. This study analysed the vertical distribution of Mps from five beaches, with one long core [Shilaoren Beach (C1), 8 m] and four short cores [Aoshan Beach (C2); Liuqinghewan Beach (C3); Bathing Beach No. 3 (C4); and Golden Beach (C5); approximately 70 cm]. An increasing trend of Mps from bottom to top layers were observed with an average of 16.6 ± 4.8 Mps/25 g d.w. in C1. Conversely, a fluctuating trend was found in C2–C5, with an average Mps abundance on the 70 cm depth to be 6.7, 7.1, 11.1 and 7.0 Mps/25 g d.w., respectively. These Mps were mainly comprised of fibres (>98%) and few were fragments. Mps were not uniformly distributed within all cores, and this variation was due to changes in Mps sources, hydrodynamics and sedimentation process in the beach environment. Although the vertical accumulation of Mps is not as stable as the other sedimentary environments, it still presents the increasing trend in the 8-m core from the bottom to the top, which is consistent with the plastic production history in China since 1950. Therefore, the 8-m core has been deposited on the beach in the recent 70 years. Thus, this study provides a valuable example for tracing the sedimentation history on the beach, which can help in understanding the sediment deposit and transport processes with time on beaches.

Biodegradation of polyvinyl chloride (PVC) by marine bacteria is a sustainable approach that leads to the production of different by-products but their toxicity needs to be evaluated. In the present study, polyvinyl chloride degradation products (PVCDP) produced by three marine bacterial isolates (T-1.3, BP-4.3 and S-237) in the culture supernatant were evaluated for toxicity on the germination of Vigna radiata and growth of Ulva lactuca. A total of 24 compounds comprising of benzene, fatty acid, ether, ester and plastic stabilizer (tris (2, 4-di-tert-butylphenyl) phosphate) were identified by GC–MS using diethyl ether solvent extraction from the supernatant. The per cent germination rate of the seed treated with PVCDP showed no significant effect but germination index and elongation inhibition rate were influenced significantly by PVCDP treatments. In seaweed (U. lactuca), PVCDP showed improvement in the daily growth rate. After ten days of treatment with PVCDP, pigment contents were improved in seaweed and PVCDP (2%) of isolate T-1.3 recorded the highest chlorophyll-a and chlorophyll-b.

Continuous input of plastic litter in ocean and coastal environments achieved alarming levels that are exposing new settings in natural systems. While novel plastic debris pollution, with rock-like appearance, has been reported worldwide, fundamentally geological analyses are still lacking. We surveyed the first occurrence of multiple associated plastic debris on a single outcrop located in a remote site (Trindade Island, SE Atlantic Ocean). Even though all plastic debris forms consisted of polypropylene and polyethylene, through a sedimentary approach (cross section, macro, and micro analyses) distinct types were identified. We detected plastiglomerates, geogenic analogous to conglomerates, divided into in situ and clastic types, and formed over beach sediment. We identified plastistones as a new type with homogeneous composition (lacking incorporated materials), geogenic-looking igneous rocks, divided into in situ and clastic types, and formed over rock surfaces. We linked pyroplastics, geogenic analogous to clasts, to clastic plastiglomerates/plastistones, therefore representing clastic types of plastic debris forms. This association was correlated in a depositional system model, which suggests that plastic debris forms are rock synthetic equivalents in which humans act as depositional and post-depositional agents.

This study provides the first assessment of the impact of the worst oil spill ever faced by Brazilian sandy beaches by analyzing changes in the community structure of intertidal macroinfauna. Four sandy beaches were sampled three times after the oil spill, and the results were compared with previous data. The first sampling, conducted 15 days after the oil spill (October 2019), showed higher abundance of macroinfauna, which decreased in subsequent sampling conducted 60 and 120 days later, but never reached a lower level than in previous sampling. Of the macroinfauna species, Scolelepis sp. was most abundant in October 2019, while Donax gemmula was predominant during the other time periods. Changes observed in macroinfauna were due to natural fluctuations rather than a response to this disturbance. Characteristics of both the oil spill and macroinfauna contributed to the lack of acute impacts.