Benthic estuarine communities' contribution to bioturbation under the experimental effect of marine heatwaves.

Marine heatwaves are increasing worldwide, with several negative impacts on biological communities and ecosystems. This 24-day study tested heatwaves' effect with distinct duration and recovery periods on benthic estuarine communities' diversity and contribution to ecosystem functioning experimentally. The communities were obtained from a temperate estuary, usually subjected to high daily thermal amplitudes. Our goal was to understand the communities' response to the thermal change, including the community descriptors and behavioural changes expected during heat extremes. We measured community composition and structural changes and the bioturbation process and nutrient release as ecosystem functioning measurements. Overall, our findings highlight the potential tolerance of studied estuarine species to the temperature ranges tested in the study, as community composition and structure were similar, independently of the warming effect. We detected a slight trend for bioturbation and nutrient release increase in the communities under warming, yet these responses were not consistent with the heatwaves exposure duration. Overall, we conclude on the complexity of estuarine communities' contribution to functioning under warming, and the importance of scalable experiments with benthic organisms' responses to climate variability, accommodating longer time scales and replication. Such an approach would set more efficient expectations towards climate change mitigation or adaptation in temperate estuarine ecosystems.

Improving the preparedness against an oil spill: Evaluation of the influence of environmental parameters on the operability of unmanned vehicles.

When an oil spill occurs, a prompt response reduces significantly the impact. The preparedness and contingency plans are essential to identify the most appropriate technologies. Unmanned and autonomous vehicles (UAVs) is emerging as a powerful tool of strategic potential in the observation, oil tracking and damage assessment of an oil spill. The SpilLess project explored the suitability of these devices to be the first-line response to an oil spill. This work analyses the operational requirements related to environmental parameters following a two steps approach: 1) Environmental characterization from long wind and waves time series and modelling; 2) Definition of the optimal periods for operating each UAVs. We have defined the periods in which each of these facilities acts best, confirming that the operational limits of UAVs are not significantly more restrictive than the traditional operations. UAVs should be included in contingency plans as available tools to fight against oil spills.

Linking contaminant distribution to hydrodynamic patterns in an urban estuary: The Douro estuary test case.

An increase in anthropogenic activities in coastal regions can put at risk their flora and fauna and their ecosystem services. Therefore, it is important to evaluate possible impacts. In particular, we need to understand the links between contaminants concentrations and the hydrodynamic patterns of these highly productive regions to anticipate the effects of contaminants in the environment. Towards that aim there is the need to carry out regular campaigns to monitor the evolution of the coastal systems. In this work we analyse in-situ measurements of physico-chemical parameters, and look for possible relations between observed contaminants patterns and estuarine hydrodynamics. Data collected in the Douro estuary, one of the main estuarine regions of the Iberian western coast, revealed the presence of 5 hazardous and noxious substances (HNS), 14 polycyclic aromatic hydrocarbons (PAHs) and 6 trace metals in water and sediment samples. Water temperature and salinity analysis revealed a strong variability, which can affect the water solubility properties and the organisms' tolerance to certain toxins. A relationship between the salinity and the HNS and PAHs concentrations was found, caused by the existence of a salt-wedge that triggers the salting-out effect. Sinker contaminants (PAHs and trace metals) can be re-suspended both during low and high flow conditions associated with the salt-wedge and with strong river flows. Floater contaminants (HNS) are completely depended on the tide, which has the capacity to distribute them through the entire estuary, during low river flow regimes. However, strong river flows, with associated river plumes, can distribute both sinker and floater contaminants to the coastal region trapping them over the inner-shelf. The results clearly show that hydrodynamic patterns are a major driver for contaminants dispersion and pathways in coastal areas, inducing harmful effects to the flora and fauna and, consequently, to the ecosystem services of these regions.

Effect of petroleum hydrocarbons in copper phytoremediation by a salt marsh plant (Juncus maritimus) and the role of autochthonous bioaugmentation.

This work aimed to investigate, under controlled but environmental relevant conditions, the effects of the presence of both inorganic and organic contaminants (copper and petroleum hydrocarbons) on phytoremediation potential of the salt marsh plant Juncus maritimus. Moreover, bioaugmentation, with an autochthonous microbial consortium (AMC) resistant to Cu, was tested, aiming an increase in the remediation potential of this plant in the presence of a co-contamination. Salt marsh plants with sediment attached to their roots were collected, placed in vessels, and kept in greenhouses, under tidal simulation. Sediments were contaminated with Cu and petroleum, and the AMC was added to half of the vessels. After 5 months, plants accumulated significant amounts of Cu but only in belowground structures. The amount of Cu was even higher in the presence of petroleum. AMC addition increased Cu accumulation in belowground tissues, despite decreasing Cu bioavailability, promoting J. maritimus phytostabilization potential. Therefore, J. maritimus has potential to phytoremediate co-contaminated sediments, and autochthonous bioaugmentation can be a valuable strategy for the recovery and management of moderately impacted estuaries. This approach can contribute for a sustainable use of the environmental resources. Graphical abstract ᅟ.

Copper phytoremediation by a salt marsh plant (Phragmites australis) enhanced by autochthonous bioaugmentation.

Here we evaluated whether the potential of Phragmites australis to phytoremediate Cu contaminated sediments could be enhanced by bioaugmentation with an autochthonous microorganism consortium (AMC) that is resistant to Cu. Saltmarsh plants with sediment attached to their roots were collected, placed in vessels and kept in greenhouses, under tidal simulation. Sediments were contaminated with Cu and the AMC was added to half of the vessels. After two months, plants accumulated significant amounts of Cu (2-10 times more) in all tissues although in higher amounts (7-10 times more) in belowground structures. AMC addition increased Cu bioavailability (5-10%) in sediments leading to a decrease in belowground structures biomass. However, bioaugmentation increased Cu translocation, with higher amounts (2 times more) of Cu in the plant stems, without significant visual toxicity signs. Therefore, autochthonous bioaugmentation can increase Cu phytoextraction potential of P. australis, which can be a valuable strategy for the recovery and management of moderately impacted estuaries.