The tidal influence on body-size spectrum of the protozoan periphytons was explored by using the conventional slide system (CS) and the polyurethane foam enveloped slide system (PFES) in coastal waters during a 1-month study. During the colonization process, clear temporal patterns of the body-size spectrum were observed using the two sampling methods. In terms of relative species number and frequency of occurrence, the rank S4 represented a more stable temporal variability in the PFES system than the CS system during the colonization. Additionally, the small forms (e.g., S1, S2, and S3) were more abundant in the PFES system. The clustering and bootstrapped average analyses demonstrated differences in body-size spectrum of protozoans between the two sampling systems. Our results imply that the body-size spectrum of protozoan periphytons may be impacted by tidal events during colonization process in marine waters.

The concentrations, sources, and ecological risks of nine trace elements in nine rivers flowing into Laizhou Bay were investigated. The dissolved element concentrations were 1.85–74.4, 0.01–0.47, 0.15–3.46, 1.54–19.7, 2.92–45.1, 1.72–11.5, 1.02–8.35, 0.10–1.02, and 21.4–185 μg/L for As, Cd, Co, Cr, Cu, Ni, Sc, Pb, and Zn, respectively. Zinc was the most abundant element in the sediments, with an average concentration of 106 mg/kg, followed by Cr (64.5 mg/kg), Cu (25.5 mg/kg), Pb (24.3 mg/kg), Ni (23.4 mg/kg), Co (10.9 mg/kg), Sc (8.14 mg/kg), As (6.75 mg/kg), and Cd (0.16 mg/kg). Elements including Co, Cr, Ni, and Sc were mainly from natural sources and As, Cd, Cu, Pb, and Zn were largely influenced by anthropogenic activities such as agricultural practice, industrial production, river transportation, and urbanization. Overall, the rivers flowing into Laizhou Bay experienced slight pollution and ecological risk. However, the severe element contamination in Jie River deserves continuous attention.

Alterations in mollusc shells have been proposed contamination biomarkers. We used geometric morphometrics analyses associated with analytical determinations of contaminants to select suitable biological models among species widely distributed on coastal zones. The study was carried out using Lottia subrugosa (herbivore limpet), Crassostrea brasiliana (filter-feeder bivalve), and Stramonita brasiliensis (carnivore gastropod) obtained along a marked contamination gradient at Santos Estuarine System (Brazil). L. subrugosa and S. brasiliensis presented distinct shapes along the gradient, while no significant differences in shell form were seen for C. brasiliana. Indeed, limpets and snails presented morphometric parameters consistent with measured contamination levels hazardous substances. Based on cross-validation models, the reliability of morphometric responses was over 75% for the herbivore and carnivore species. In addition, for S. brasiliensis, a 95.2% confidence was detected in most contaminated sites. Therefore, shell alterations on carnivorous gastropods should be further investigated, seeking to be effectively employed as pollution biomarkers.

Potentially hazardous metals (PHMs) in the coastal environment have become a great concern due to their easy bioaccumulation, poor biodegradability and high toxicity. Surface sediment samples were collected in a subtropical bay in South China to analyse the spatial variations, contamination level and potential sources of PHMs. The results indicated that the order of average contents of PHMs in Qinzhou Bay sediment was Zn > Pb > Cr > Cu > As > Hg > Cd. The most important potential ecological risk factor was Hg pollution in the Qinzhou Bay sediments. The positive matrix factorization (PMF) model results indicated that Cu, Pb, Zn, Cd and Cr mainly originated from natural sources while Hg and As were related to coal fired industrial inputs and petroleum production activities. The results could provide a basis for marine management to formulate relevant pollution prevention and control measures.

The present study aims to assess the effects of contamination of the Agadir bay coasts using bivalves as a biomonitoring sentinel species. Seasonal variations of biochemical composition in terms of total protein content and oxidative stress biomarkers including glutathione-S-transferase, malondialdehyde, catalase and acetylcholinesterase were evaluated in the soft tissues of Scrobicularia plana and Donax trunculus specimens. The latter were collected from two sites in Agadir bay during two-year span (2018–2020). The Integrated Biomarker Response Index (IBR) was performed to classify the stress response in both species and to assess the level of exposure to xenobiotics. The data showed maximum annual values of acetylcholinesterase and malondialdehyde for Donax trunculus in Agadir beach (AG) with 6.25 nmol/mn/mg and 3 nmol/mg of protein, respectively. Those of catalase and glutathione-S-transferase for Scrobicularia plana in Oued Souss estuary (OS) were of 4.41 μmol/mn/mg and 14.43 nmol/mn/mg of protein, respectively. The studied species are considered good indicators in aquatic ecosystems.

Alegranza is the most northerly island of the Canary Islands archipelago, the first obstacle crossed by the Canary Current. From July to October 2020, six expeditions were led to the island to make a first inventory of marine debris and its possible source and origin. In total, 3667 objects weighing 321 kg were removed, excluding wooden objects. Of these, 97.7% were plastics, the most abundant being drink bottles (25.4%). While knowing the origin, source and pathway of debris is difficult, legible labels provided valuable information. In Alegranza, 66.7% of the legible bottle labels indicated Asian countries of manufacture, which is evidence that the source is maritime traffic in the region. The lobster trap license labels from the east coast of the United States and Canada were dated from 1999 to 2018, supporting both the exogenous origin and long lifetime in the ocean of these debris.

Ten benthic fauna taxa in a polluted marine area adjacent to McMurdo Station, Antarctica were deemed to be potential biomonitors because PCBs, DDTs, PAHs, copper, lead and/or zinc in their tissues were significantly higher than in tissues of taxa living in reference areas (p < 0.05). Concentrations of PCBs and DDT were highest in Trematomus (fish). Total PAH concentrations were highest in Alcyonium antarcticum (soft coral), Isotealia antarctica (anemone) and L. elliptica. Copper and lead concentrations were highest in Laternula elliptica (bivalve) and Flabegraviera mundata (polychaete), and lowest in Trematomus and Parbolasia corrugatus (nemertean). However, copper concentrations were even higher in the asteroids Perknaster fuscus antarcticus, Odontaster validus and Psilaster charcoti. Bioaccumulation factors for different species were highest for PCBs and DDT, and lowest for lead. Bioaccumulation of some contaminants are likely prevalent in benthic taxa at McMurdo Station, but concentrations are usually low relative to human consumption standards.

The transporting of oil via the Arabian Gulf for centuries has resulted in the pollution of the coasts by heavy metals, and therefore, remediation actions are needed. In this review, we first evaluated heavy metal pollution on the coasts by assembling the research on published metal concentrations in sediments and water bodies surrounding the Arabian Peninsula. Research revealed uneven pollution of heavy metals, meaning that before remediation, the most polluted sites should be found. This could be done most conveniently using biomonitoring. The Arabian Peninsula is a unique ecoregion due to the extremely high temperature in summer, and therefore, it needs its specific standardization procedure for biomonitoring. To get an overview of the current information on biomonitoring, we gathered a dataset of 306 published macroalgal observations from the Arabian Gulf and the Gulf of Aden. The heavy metal concentration dataset of macroalgae was analyzed with a multivariate principal component analysis. As a result of the published works elsewhere and our data analysis, we recommend that green Ulva and brown Padina species are used in the biomonitoring of heavy metal pollution on the Arabian Peninsula's eastern and southern coasts. However, more species might be needed if these species do not occur at the site. The species incidence should first be monitored systematically in each area, and common species should be used. The species used should be chosen locally and sampled at the same depth at low tide in spring or early summer, from February to May, before the hottest season. The composite samples of different apical sections of the thallus should be collected. The standardization of the monitoring processes benefits future remediation actions.

In recent years, the North Atlantic and the Caribbean Sea have experienced unusual and unprecedented pelagic Sargassum blooms, which may adversely affect coastal ecosystems and productive ocean. Sargassum has the potential to scavenge trace elements and radionuclides from seawater, and when bioaccumulated and thus concentrated, can pose a potential threat to higher trophic organisms, including humans that consume impacted seafood. In this study, trace elements and naturally-occurring U/Th-series radionuclides were measured in Sargassum that were collected in the coastal waters of the Caribbean Sea (Antigua/Barbuda, Belize, and Barbados) to better define baseline concentrations and activities, and to assess the scavenging potential for these trace elements and radionuclides. The mean concentration of trace elements observed in Sargassum collected across these three Caribbean Sea are ranked accordingly to the following descending order: Sr > As>Fe > Mn > Zn > Ni > V > C > Cd > Se > Co > Cr > Pb > Ag > Hg. 210-Po and ²¹⁰Pb activities in Sargassum were observed to be more elevated than previously reported values.