Título: Anthropogenic microparticles as heavy metal vectors: implications for marine contaminantion and food webs

Área Científica: Ciências da Terra e do Ambiente

Sub-área: Ciências do Ambiente

Sumário (max. 150 palavras):

Coastal areas have a great ecological value as ecosystem services providers [1,2,3]. An important role has been admitted by the inclusion of these ecosystems in the Water Framework Directive (WFD) and in the Marine Strategy Framework Directive (MSFD) [6]. Heavy metals (HMs) have been widely studied in these systems [1,4,5,6,7,8]. Anthropogenic microparticles (MPs) are the new concern while evaluating ecological status of marine systems travelling along the hydrodynamic gradient carrying HMs [12]. This project will provide answers in the remediative role of these ecosystems as MPs and HMs sinks. This travel through coastal gradients also subjects MPs to a physic-chemical gradient shaping the sorption/desorption of HMs to MPs surface [12], entering the food chain [13]. HMs-MPs couples versus single effects in different trophic levels, acquires additional meaning under the MSFD scope in commercially exploited species. This multi-disciplinary approach intent to fill the gaps between HMs-MPs at the ecosystem level.

Estado da Arte (max. 500 palavras):

HMs are well-known contaminants with recognized effects in marine MOs, plants and animals [6,7,11]. Estuarine ecosystems are key ecosystems for the remediation of marine systems [8,9,10] provided by salt marshes acting as active sinks of pollutants [1,4,5].Estuarine hydrodynamics, settle passive particles charged with HMs on salt marshes, promoting sedimentation [2,3]. MPs are no different and exhibit a passive Lagrangean drift [8]. Studies regarding anthropogenic MPs have increased [14] and this also caught attention in conventions and directives. Mankind uses about 240M tons of plastic discarding these materials into the marine environments [20]. This debris undergoes degradation into smaller particles [14]. Plastics are persistent pollutants ending up on the bottom of all kind of marine environments [14]. The widespread has prompted several agencies (UN, IOC, EU, NOAA) even the OSPAR convention to improve our understanding about how MPs contamination is, accumulation, sources and impacts. In addition to their aesthetic impacts, MPs are threatening animals by accumulation and entanglement [15], and it can be easily mistaken as food [20]. HMs-MPs interactions hadn’t been considered because polymers were mentioned to be inert towards metal ions [12] although the association mechanism is unclear, involve adsorption of ions to polymers and adherence of metal-bearing mineral particles to MPs surface [12]. Buoyancy of pellets ensures MPs exposition to high HM concentrations in the surface microlayer. In marine environments can travels considerable distances being potentially available to animals [17] and is even more unknown in systems very marked physic-chemical gradient changing ion solubility [14]. If one considers predicted physic-chemical changes derived from climate change [8] the scarcity data on HMs-MPs interaction is even higher. If their static behavior while HMs vectors has a high degree of uncertainty, their dynamics while

passive particles transported along a coastal system is almost case-specific. Numerical modellings coupled to in situ data contribute efficiently particulate HMs trajectories along the system [8] and also be applied to MPs due to their Langrangean behavior [16]. Stable isotopes can establish mass and energy balances along food webs providing insights on contaminant flows. IsoWeb model, estimates diet proportions of all consumers in a food web based on stable isotope information, taking into account variation in trophic enrichment factors among different consumer-resource links [18]. The knowledge about how different food webs and its elements incorporate persistent contaminants is yet to be known. MPs ingestion has physical impacts and physiological consequences on the population fitness [13]. Biochemical markers can characterize the contaminant fraction and integrate effects of contaminants experienced by organisms [19]. They are powerful tools to measure xenobiotic effects [19]. In sum, the acquisition of knowledge proposed by this PhD plan, intents to suppress the major gaps in this area [20]. A clear view of the MPs contamination history for the target systems coupled with hydrodynamic approach will provide answers to these gaps. Their Interactions with HMs, MOs and animals is essential for understanding ecological impacts, MSFD sensu and proving technical information for impact assessment and scientific knowledge to answer questions demonstrated by the literature review.

Objectivos (max. 300 palavras):

Descrição Detalhada (max. 1000 palavras):

Facing the lack of knowledge on the interactions between MPs and the well-known HM contaminants present in the Tagus and in Madeira coastal areas, a multi-disciplinary approach will be undertaken, from geology to hydrodynamics, passing by animal physiology and ecotoxicology and marine chemistry. These two marine systems have contrasting contamination histories. Tagus industrial history is well known and it’s markedly recorded in several research papers and in the sediment record. On the other hand, Madeira archipelagos is away from any kind of industrial activity but it’s highly affected by a large volume of marine traffic. This intense ship movement will introduce some contamination sources to this marine ecosystem, such as metal release from anti-fouling paints or MPs generation from marine litter introduction. First, to understand the present pollution of our estuaries, there is the need to unravel the past history of MP contaminations, similarly to what is known for HMs. Salt marshes are known to constitute good records of the contamination history of an estuary, as they act as sinks integrating in their sediments contaminants and drifting material. Different salt marshes located along the Tagus estuarine shoreline will be sampled for sediment cores in order to establish a chronology based on the 137Cs dating. This will allow understanding when MPs started to appear in the estuarine system with different levels of anthropogenic pressure and simultaneously their relationships with the HM contamination between 1900 and the sampling date. The same approach will be employed in Madeira coastal area. Alongside this historical reconstruction, it’s also important to understand the present status of contamination of both marine systems. While sediments are good historical records for contaminants, the water column can provide real-time Information. Sampling MPs present in the water column surface within a pre-established sampling grid will provide powerful insights to feed hydrodynamic models. The HM contamination in the water column and in the drifting MPs will

be assessed, in order to understand their role as vectors of chemical contamination. MPs behave as drifting Lagrangean particles and thus have their movement controlled by the system hydrodynamic features. This approach will allow identifying possible sources and destinations of the MPs and associated contaminants. Simultaneously, a chemical approach will be undertaken, analyzing the dissociation and adsorption processes of HMs from MPs using Langmuir and Freundlich models, providing insights on the chemical equilibrium of the contaminants present in the dissolved phase and in the particulate phase, namely in the MPs. This merger of hydrodynamic and chemical models, will provide a map of the contaminant transport and dissolution along the physic-chemical gradient modeled mostly by salinity, and thus the availability and transport of the different chemical contaminants as well as the MPs hazardous characteristics as contaminant carriers. Fishes and macroinvertebrates can play a key role in the ecosystem-contaminant interactions. These are important to consider in terms of MPs mass balances and associated contaminants. Fishes and invertebrates will be sampled and their MPs content determined both incorporated in the muscle and in their stomach. Comparing animals from similar sites and with different MPs concentrations, it is expected to establish a relationship between MPs and HMs concentrations in the animals, in order to understand the effect of the MPs as contamination vectors. This is important in terms of economically exploitable species such as mussels, mollusks and barnacles. Additionally, biological invasions by non-indigenous species (NIS) are considered one of the greatest environmental and economic threats to global biodiversity. Studies have been indicating that NIS are more resistant to several types of stresses. Comparing different MPs concentrations between NIS and sister native species could provide key and novel insights. The analysis of the d13C and d15N stable isotopes coupled with isotope-based trophic models (IsoWeb) allows a better understanding the energy and mass flow along the estuarine trophic web, and thus the potential MPs and contaminant transfers between trophic levels. This will lately be coupled with animal manipulation experiments. Nevertheless, marine environments are subjected to physic-chemical gradients, with known effects on the adsorption/desorption of contaminants between the particulate (SPM and MPs) and dissolved phases. Using controlled mesocosmos, several at present and predicted pH, salinity and temperature conditions will be simulated using estuarine water and controlled MPs (with different morphologies and materials) and contaminant concentrations in order to assess the effect of the present and future estuarine gradients on the MPs carrier capacity. Using a similar mesocosmos approach the stomach content of some animals (fishes and invertebrates) will be simulated. Our major goal is to understand the desorption rates of the contaminants from the MPs surface to the digestive environment and to the animal cells. This will provide new insights on the MPs impact in the animal contaminant burden. Exposing representative species with different feeding habits to different types of contaminated and non-contaminated MPs, created in a controlled environment will provide data on the physiological fitness of these animals towards the exposure to contaminants both carried by MPs and by simple water/sediment ingestion. At this level several condition and physiological biomarkers will be employed ranging from genotoxicity and proteomic analysis to typical enzymatic biomarker assessment. Since there exists a large number of commercially exploited species potentially affected by MPs contaminations, also their ability to be depurated will be tested maintaining the animals in a controlled environment without any levels of contamination. This is very important in terms of food security and public health, as these MPs particles are not currently monitored in these economically exploited species and thus their presence can present a threat to the human consumers, not only by the coupled-contaminants but also as contaminants itself. With these multi-disciplinary approaches the present consortium intents to provide science answers, but

also guidance document for the management and protection of marine ecosystems to be presented to the stakeholders and authorities. Also within the scope of the WFD and MSFD these insights acquire an increased importance as they will provide recommendations for both monitoring and mitigation programs of priority substances (HMs-MPs) considered key features within the ecological quality status assessment imposed by both directives.

Referências (max. 20):

1. Caçador, I., C. Vale and F.M. Catarino, 1996. Accumulation of Zn, Pb, Cu, Cr and Ni in Sediments Between Roots of the Tagus Estuary Salt Marshes, Portugal. Estuarine, Coastal and Shelf Science 42:393-403

2. Salgueiro, N. & I. Caçador (2007). Short-term sedimentation in Tagus estuary, Portugal: the influence of salt marsh plants. Hydrobiologia 587:185-193.

3. Duarte, B., Caçador, I., Marques, J.C. and Croudace, I., 2013. Tagus Estuary salt marshes feedback to sea level rise over a 40-year period: insights from the application of geochemical indices. Ecological Indicators 34, 268-276.

4. Caçador, I., Caetano, M., Duarte, B., Vale, C. 2009. Stock and losses of trace metals from salt marsh plants. Marine Environmental Research, 67, 75-82.

5. Duarte, B., Caetano, M., Almeida, P., Vale, C., Caçador, I., 2010. Accumulation and biological cycling of heavy metal in the root-sediment system of four salt marsh species, from Tagus estuary (Portugal). Environmental Pollution 158, 1661-1668.

6. Santos, D., Duarte, B. and Caçador, I., 2014. Unveiling Zn hyperacumulation in Juncus acutus: implications on the electronic energy fluxes and on oxidative stress with emphasis on non-functional Zn-Chlorophylls. Journal of Photochemistry and Photobiology B: Biology 140, 228-239.

7. Pedro, S., Duarte, B., Castro, N., Almeida, P.R., Caçador, I. and Costa, J.L., 2015. The Lusitanian Toadfish as biomonitor of estuarine sediment metal burden: the influence of gender and reproductive metabolism. Ecological Indicators 48, 370-379.

8. Duarte, B., Valentim, J.M., Dias, J.M., Silva, H., Marques, J.C. and Caçador, I., 2014. Modelling Sea Level Rise (SLR) impacts on salt marsh detrital outwelling C and N exports from an estuarine coastal lagoon to the ocean (Ria de Aveiro, Portugal). Ecological Modelling 289, 36-44.

9. Duarte B. and Caçador, I., 2012. Particulate metal distribution in Tagus Estuary (Portugal), during a flood episode. Marine Pollution Bulletin 64, 2109–2116.

10. Duarte, B., Silva, G., Costa, J.L., Medeiros, J.P., Azeda, C., Sá, E., Metelo, I., Costa, M.J. and Caçador, I., 2014. Heavy metal distribution and partitioning in the vicinity of the discharge areas of Lisbon drainage basins (Tagus Estuary, Portugal). Journal of Sea Research 93, 101-111.

11. Duarte, B., Reboreda, R., Caçador, I. 2008. Seasonal variation of Extracellular Enzymatic Activity (EEA) and its influence on metal speciation in a polluted salt marsh. Chemosphere, 73, 1056-1063.

12. Holmes, L.A., Turner, A. and Thompson, R.C., 2012. Adsorption of trace metals to plastic resin pellets in the marine environment. Environmental Pollution 160, 42-48.

13. Sá, L.C., Luís, L.G. and Guilhermino, L., 2015. Effects of microplastics on juveniles of the common goby (Pomatoschistus microps): Confusion with prey, reduction of the predatory performance and efficiency, and possible influence of developmental conditions. Environmental Pollution 196, 359-362.

14. Browne, M.A., Crump, P., Niven, S.J., Teuten, E., Tonkin, A., Galloway, T. and Thompson R., 2011. Accumulation of Microplastic on Shorelines Woldwide: Sources and Sinks. Environmental Science and Technology 45, 9175–9179.

15. Gregory, M.R., 2009. Environmental implications of plastic debris in marine settings-entanglement, ingestion, smothering, hangers-on, hitch-hiking and alien invasions. Philosophical Transactions of the Royal Society B 364, 2013-2025.

16. Maximenko, N., Hafner, J., Niiler, P., 2012. Pathways of marine debris derived from trajectories of Lagrangian drifters. Marine Pollution Bulletin 65, 51–62.

17. Tourinho, P.S., Ivar do Sul, J.A., Fillmann, G., 2010. Is marine debris ingestion still a problem for the coastal marine biota of southern Brazil? Marine Pollution Bulletin 60, 396-401.

18. Kadoya, T., Osada, Y. and Takimoto, G., 2012. IsoWeb: A Bayesian Isotope Mixing Model for Diet Analysis of the Whole Food Web. PLoS ONE 7, e41057.

19. Kumari, K., Khare, A. and Dange, S., 2014. The Applicability of Oxidative Stress Biomarkers in Assessing Chromium Induced Toxicity in the Fish Labeo rohita. BioMed Research International vol. 2014, Article ID 782493.

20. Wrigh,. S.L., Thompson, R.C. and Galloway, T.S., 2013. The physical impacts of microplastics on marine organisms: A review. Envrionmental Pollution 178, 483-492.