Browsing by Author "Zardi, Gerardo, I"
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- A baseline assessment of beach macrolitter and microplastics along northeastern Atlantic shoresPublication . Velez, Nadja; Zardi, Gerardo, I; Lo Savio, Roberto; McQuaid, Christopher D.; Valbusa, Ugo; Sabour, Brahim; Nicastro, KatyMarine litter is widely dispersed throughout coastal environments. Assessing the distribution and accumulation of such contaminants is crucial to understand their environmental impacts. This study presents a baseline for the monitoring of litter and microplastics in intertidal sediments along the Atlantic shores of southern Portugal and Morocco and identifies potential sources of contamination. Although variable, distribution and composition of both litter and microplastics did not follow a latitudinal pattern. Most of the litter had an undifferentiated source. Within the identifiable sources of litter, food packaging, fishing and tobacco were the most abundant, with variable contributions among sites. Over 97% of marine litter retrieved was plastic. Fragments and filaments were the most abundant categories of plastics at sites with the highest and lowest microplastic abundance respectively. Filaments were mainly made of Polypropylene (PP,50%) and Polyethylene terephthalate (PET,29%) while the predominant polymers for fragments were Polyethene (PE, 75%) and PP (25%).
- Between a rock and a hard place: combined effect of trampling and phototrophic shell-degrading endoliths in marine intertidal musselsPublication . Nicastro, Katy; McQuaid, Christopher; Zardi, Gerardo, IEcosystems often face a complex combination of natural and anthropogenic disturbances. The assessment of anthropogenic pressures and co-occurring natural stressors is crucial to our understanding of ecosystem structures, dynamics and their conservation. The present study provides the first experimental assessment of the combined effects of trampling (anthropogenic stressor) and endolithic induced erosion (natural stressor) on two coexisting intertidal mussel species, Mytilus galloprovincialis (de Lamarck, 1819) and Perna perna (Linnaeus, 1758). Mixed beds of the two species experiencing a wide range of endolithic parasitation were exposed to increasing intensities of human trampling. Our results clearly show that endolith-infested mussels are more vulnerable to trampling than non-infested individuals. At high trampling intensities, P. perna suffered significantly lower mortalities rates than M. galloprovincialis. More than 20% of large, infested M. galloprovincialis individuals were crushed even at low trampling intensities. Unexpectedly, mortalities rates decreased with mussel size, suggesting a sheltering role of larger conspecifics. Beyond ecological interest, such findings can provide critical experimental support for conservation and management actions.
- Congruence between fine-scale genetic breaks and dispersal potential in an estuarine seaweed across multiple transition zonesPublication . Nicastro, Katy; Assis, J.; Serrao, Ester; Pearson, Gareth; Neiva, J.; Valero, Myriam; Jacinto, Rita; Zardi, Gerardo, IGenetic structure in biogeographical transition zones can be shaped by several factors including limited dispersal across barriers, admixture following secondary contact, differential selection, and mating incompatibility. A striking example is found in Northwest France and Northwest Spain, where the estuarine seaweed Fucus ceranoides L. exhibits sharp, regional genetic clustering. This pattern has been related to historical population fragmentation and divergence into distinct glacial refugia, followed by post-glacial expansion and secondary contact. The contemporary persistence of sharp ancient genetic breaks between nearby estuaries has been attributed to prior colonization effects (density barriers) but the effect of oceanographic barriers has not been tested. Here, through a combination of mesoscale sampling (15 consecutive populations) and population genetic data (mtIGS) in NW France, we define regional genetic disjunctions similar to those described in NW Iberia. Most importantly, using high resolution dispersal simulations for Brittany and Iberian populations, we provide evidence for a central role of contemporary hydrodynamics in maintaining genetic breaks across these two major biogeographic transition zones. Our findings further show the importance of a comprehensive understanding of oceanographic regimes in hydrodynamically complex coastal regions to explain the maintenance of sharp genetic breaks along continuously populated coastlines.
- Intraspecific diversity in an ecological engineer functionally trumps interspecific diversity in shaping community structurePublication . Nicastro, Katy; McQuaid, Christopher D.; Dievart, Alexia; Zardi, Gerardo, ICan intraspecific diversity functionally supersede interspecific diversity? Recent studies have established the ecological effects of intraspecific variation on a number of ecosystem dynamics including resilience and productivity and we hypothesised that they may functionally exceed those of species diversity. We focused on a coastal ecosystem dominated by two coexisting bioengineering mussel species, one of which, Perna perna, displays two distinct phylogeographic lineages. A manipulative field experiment revealed greater habitat structural complexity and a more benign microscale environment within beds of the eastern lineage than those of the western lineage or the second species (Mytilus galloprovincialis)
- Microplastic leachates induce species-specific trait strengthening in intertidal musselsPublication . Seuront, Laurent; Nicastro, Katy; McQuaid, Christopher D.; Zardi, Gerardo, IPlastic pollution is ubiquitous with increasing recognition of its direct effects on species’ fitness. Little is known, however, about its more subtle effects, including the influence of plastic pollution on the morphological, functional and behavioral traits of organisms that are central to their ability to withstand disturbances. Among the least obvious but most pernicious forms of plastic-associated pollution are the chemicals that leach from microplastics. Here, we investigate how such leachates influence species’ traits by assessing functional trait compensation across four species of intertidal mussels, through investigations of byssal thread production, movement and aggregation behavior for mussels held in natural seawater or seawater contaminated by microplastic leachates. We found no evidence for compensation of functional traits, but for each species, microplastic leachates reinforced one trait while others remained unaffected. Two species (Perna perna and Mytilus galloprovincialis), were characterized by a resistance strategy to disturbance; they produced more byssal threads in microplastic leachate seawater than in control seawater, while motility and aggregation remained essentially unaffected. In contrast, the other two species (M. edulis and Choromytilus meridionalis), showed a resilience strategy to disturbance through increased motility and aggregation in leachate seawater, while byssal thread production remained unaffected. These results suggest that the competitive abilities of intertidal mussels may be related to their sensitivity to microplastic leachates or other chemical disturbance. Importantly, the trait strengthening observed will affect the ability of these mussels to form spatially patterned beds, with implications for their quality as autogenic ecological engineers or foundation species. Thus, our findings have implications for the ability of mussel beds to tolerate disturbance, and hence for central ecosystem services, such as their ability to support biodiversity and enhance secondary and tertiary production. The results suggest that an inconspicuous aspect of plastic pollution has the potential to influence other communities and ecosystems in powerful ways.
- Plastic ingestion in aquatic birds in PortugalPublication . Basto, Marta; Nicastro, Katy; Tavares, Ana I; McQuaid, Christopher D.; Casero, Maria; Azevedo, Fabia; Zardi, Gerardo, IIn modem society, plastic items have become indispensable. The rapid growth of plastic production has led to an increase in the concentration of plastic waste in the environment and, consequently, wildlife has been severely affected. As wide-ranging foragers and predators, aquatic birds are ideal sentinels for monitoring changes in their environment. Plastic found in stomach contents of stranded aquatic birds collected throughout Portugal was examined. Out of the 288 birds processed, 12.9% ingested plastics. Six of the 16 species assessed showed evidence of plastic ingestion. The Lesser Black-backed Gull (18.7%) had the highest incidence while, among those that did ingest plastics, the Northern Gannet (4.8%) had the lowest. User plastics were the most common type of plastic ingested, while microplastics and off/white-clear were the most common size and colour respectively of plastics found. This study sets a first multispecies baseline for incidence of plastic ingestion by aquatic birds in Portugal.