This study aimed to identify ocean- and land-based sources of nutrients to the coral reef communities surrounding the Southern Caribbean islands Aruba, Bonaire, and Curaçao (ABC islands). The composition of water masses around these islands were assessed to depths up to 300 m and three distinct overlying water masses were identified, separated by mixing zones. A fluctuating pycnocline separating surface from deeper (>∼50 m) water indicated the presence of internal waves. Nutrient profiles were typical of tropical waters with oligotrophic waters occurring above the pycnocline and a deep chlorophyll-a maximum (DCM) just below it (∼65 m). Concentrations of dissolved nutrients differed among islands. Inorganic nitrogen (DIN) and phosphate concentrations were respectively lowest around Bonaire and Curaçao. The spatial distribution of chlorophyll-a (indicative of phytoplankton biomass), rather than nutrient concentrations, suggested the presence of higher-than-average nutrient concentrations in islands with higher population densities and near urbanized/industrial areas.

Marine plastic pollution poses significant ecological, economic, and social challenges, necessitating innovative detection, management, and mitigation solutions. Spectral imaging and optical remote sensing have proven valuable tools in detecting and characterizing macroplastics in aquatic environments. Despite numerous studies focusing on bands of interest in the shortwave infrared spectrum, the high cost of sensors in this range makes it difficult to mass-produce them for long-term and large-scale applications. Therefore, we present the assessment and transfer of various machine learning models across four datasets to identify the key bands for detecting and classifying the most prevalent plastics in the marine environment within the visible and near-infrared (VNIR) range. Our study uses four different databases ranging from virgin plastics under laboratory conditions to weather plastics under field conditions. We used Sequential Feature Selection (SFS) and Random Forest (RF) models for the optimal band selection. The significance of homogeneous backgrounds for accurate detection is highlighted by a 97 % accuracy, and successful band transfers between datasets (87 %–91 %) suggest the feasibility of a sensor applicable across various scenarios. However, the model transfer requires further training for each specific dataset to achieve optimal accuracy. The results underscore the potential for broader application with continued refinement and expanded training datasets. Our findings provide valuable information for developing compelling and affordable detection sensors to address plastic pollution in coastal areas. This work paves the way towards enhancing the accuracy of marine litter detection and reduction globally, contributing to a sustainable future for our oceans.

Catchment-scale plastic pollution assessments provide insights in its sources, sinks, and pathways. We present an approach to quantify macroplastic transport and density across the Odaw catchment, Ghana. We divided the catchment into the non-urban riverine, urban riverine, and urban tidal zones. Macroplastic transport and density on riverbanks and land were monitored at ten locations in December 2021. The urban riverine zone had the highest transport, and the urban tidal zone had the highest riverbank and land macroplastic density. Water sachets, soft fragments, and foam fragments were the most abundant items. Our approach aims to be transferable to other catchments globally.

A bottleneck in restoring self-sustaining beds of the European oyster (Ostrea edulis) is the successful development and settlement of larvae to bottom habitats. These processes are largely governed by temperature but a mechanistic understanding of larval performance across ecologically relevant temperatures is lacking. We reared larvae at low (20–21 °C) and high (20–24 °C) fluctuating temperatures and applied short-term exposures of larvae to temperatures between 16 and 33 °C to assess vital rates and thermal coping ranges. Larval thermal preference was between 25 and 30 °C for both rearing treatments which corresponded with optimum temperatures for oxygen consumption rates and locomotion. Larvae had 5.5-fold higher settling success, however, when reared at the high compared to the low fluctuating temperatures. Higher mean and periods of increased temperature, as projected in a future climate, may therefore enhance recruitment success of O. edulis in northern European habitats.

Sargassum spp. strandings in the tropical Atlantic harm local ecosystems due to toxic sulfide levels. We conducted a mesocosm experiment to test the efficacy of iron(III) (hydr)oxides in (a) mitigating sulfide toxicity in mangroves resulting from Sargassum and (b) reducing potentially enhanced greenhouse gas emissions. Our results show that iron addition failed to prevent mangrove mortality caused by highly toxic sulfide concentrations, which reached up to 15,000 μmol l−1 in 14 days; timely removal may potentially prevent mangrove death. Sargassum-impacted mesocosms significantly increased methane, nitrous oxide, and carbon dioxide emissions, producing approximately 1 g CO2-equivalents m−2 h−1 during daylight hours, thereby shifting mangroves from sinks to sources of greenhouse gasses. However, iron addition decreased methane emissions by 62 % and nitrous oxide emissions by 57 %. This research reveals that Sargassum strandings have multiple adverse effects related to chemical and ecological dynamics in mangrove ecosystems, including greenhouse gas emissions.

International audience | Treatment Wetlands (TW) are employed in the treatment of wastewater, participating in a decentralised and sustainable urban water management. Their designs and usages vary greatly across the world, which limit the aggregation of comparable data for deeper understanding of the mechanisms ruling over water treatment. We developed a hybrid modelling methodology to combine mechanistic and empirical pre-sizing models, applied to a context of low amount of data and knowledge on Horizontal and Vertical Flow TW. We first collected data from the scientific literature and introduced a data quality validation step providing reliability weights associated with each observation. We secondly trained and compared machine-learning models on the assessed dataset. We finally tested two hybridizations with the tank-in-series model, and predicting an optimized surface with a uncertainty interval. This methodology is reproducible and we believe hybrid models can provide more accurate and reliable predictions, therefore facilitating implementations of TW in urban plannings.

Cryptic species are rarely considered in ecotoxicology, resulting in misleading outcomes when using a single morphospecies that encompasses multiple cryptic species. This oversight contributes to the lack of reproducibility in ecotoxicological experiments and promotes unreliable extrapolations. The important question of ecological differentiation and the sensitivity of cryptic species is rarely tackled, leaving a substantial knowledge gap regarding the vulnerability of individual cryptic species within species complexes. In times of agricultural intensification and the frequent use of pesticides, there is an urgent need for a better understanding of the vulnerability of species complexes and possible differences in adaptive processes. We used the cryptic species complex of the aquatic amphipod Gammarus roeselii, which comprises at least 13 genetic mtDNA lineages and spans from small-scale endemic lineages in Greece to a large-scale widely distributed lineage in central Europe. We exposed eleven populations belonging to four lineages to the neonicotinoid thiacloprid in an acute toxicity assay. We recorded various environmental variables in each habitat to assess the potential pre-exposure of the populations to contaminants. Our results showed that the populations differed up to 4-fold in their tolerances. The lineage identity had a rather minor influence, suggesting that the cryptic species complex G. roeselii does not differ significantly in tolerance to the neonicotinoid thiacloprid. However, the observed population differentiation implies that recent pre-exposure to thiacloprid (or similar substances) or general habitat contamination has triggered adaptive processes. Though, the extent to which these mechanisms are equally triggered in all lineages needs to be addressed in the future. Our study provides two key findings: Firstly, it shows that observed phylogenetic differences within the G. roeselii species complex did not reveal differences in thiacloprid tolerance. Second, it confirms that differentiation occurs at the population level, highlighting that susceptibility to toxicants is population-dependent. The population-specific differences were within the range of accepted intraspecific variability from a regulatory standpoint. From an evolutionary-ecological perspective, it remains intriguing to observe how persistent stresses will continue to influence tolerance and whether different populations are on distinct pathways of adaptation. Given that the potential selection process has only lasted a relatively short number of generations, it is crucial to monitor these populations in the future, as even brief exposure periods significantly impact evolutionary responses.

The metropolis of Kolkata stands uniquely positioned to implement a natural sewage treatment paradigm through the utilization of waste stabilization ponds, specifically within the East Kolkata Wetlands (EKW). These shallow oxidation ponds harness solar irradiation and algae bacteria symbiotic processes to effectively treat incoming sewage. Concurrently, nutrient-rich effluents are assimilated through fish production, converting available nutrients into protein—a hallmark of nature-based treatment. A portion of raw sewage is used to cultivate a chunk of vegetables before treatment in fish ponds, and the reclaimed water after treatment is used for vegetable and paddy cultivation downstream. This investigation explains the delineation of a sewage flow system to EKW, a Ramsar-designated site. Substantively, it offers quantitative insights into the sewage volumes and quality undergoing treatment. The sewage flow is higher in the winter months (909.07 MLD) compared to the summer months (709.34 MLD). In general, the sewage from the Kolkata city flowing to the EKW is moderately polluted. Extensive scrutiny of sewage from pond inlets and outlets serves as a quantitative metric for evaluating treatment efficacy. EKW efficiently treats the sewage, demonstrating 59.1% Biological Oxygen Demand (BOD) removal and a 99.28% reduction in fecal coliform. The natural treatment system excels in removing ammoniacal nitrogen (80.38%) and phosphate (90%). The treated water’s quality along the EKW boundary, culminating at the Kulti Gong River discharge point, was systematically assessed. Analytical findings indicate that all measured concentrations in the treated water adhere to prescribed inland surface water discharge standards prescribed by the Central Pollution Control Board, India, barring a marginal elevation in BOD during winter. Evidently, the EKW system adeptly manages substantial sewage volumes, fostering efficient treatment while concurrently facilitating resource recovery through fish production, yielding economic dividends. Despite its substantial land footprint, preserving this inherently sustainable wastewater management paradigm is imperative.

This study was conducted in Barangay Badiangan, Ajuy, Iloilo City, Philippines (11°10’N, 122°58’E) to determine the effects of rainfall intensity and other rainfall-derived parameters on the directional components of splash erosion in hillslopes. There are five experimental set-ups with slope angles ranging from 0% to 48% were tested under natural rainfall conditions using a modified splash collector. The data collected shows that kinetic energy, slope, and rainfall intensity have shown significant effects on splash erosion. The models obtained using regression analysis are 𝑄𝑄𝑑𝑑𝑑𝑑𝑑𝑑=0.0093(𝐾𝐾𝐾𝐾0.80) and 𝑄𝑄𝑡 𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡=0.060(𝐾𝐾𝐾𝐾0.107)(𝑆𝑆0.700)(𝐼𝐼200.700) . The model equation performance has been validated using the Standard Error of Estimates with values of 12 and 9.4 for splash detachment and splash transport, respectively. The constants used for kinetic energy in detachment and slope in transport align with the research by Quansah (1981) for sandy soil, which is similar (the characteristics) to the soil at our research site. Additionally, rainfall intensity, especially with a 20-min duration, generated the best model as it yielded the lowest SEE value for all cases.