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We assessed the influence of different organic matter (OM) inputs associated with terrigenous/freshwater allochthonous and sewage derive on bioturbation and irrigation potential community indices (BPc and IPc) of the soft-bottom macrofauna community. The macrofauna was sampled from two different sedimentary impacted areas, in front of the Po River Delta (northern Adriatic Sea) and sewage discharge diffusion zone (Gulf of Trieste). The highest values of BPc and IPc were observed at the northward sampling stations of the prodelta and the stations 25 m distance in front of the main sewage outfall. Species richness showed high values in the prodelta likely due to the OM positive effect from the delta, and it increased with increasing distance from the pipeline due to the effect of OM from the sewage discharge. The bioturbation indices differed due to the presence of surface deposit feeders and the injection depth (from 2 to 5 cm) with limited movement at the station located northwards in the prodelta and 25 m distance in the diffusion zone. We infer that the difference in bioturbation indices was likely due to the effects of grain-size composition and the degree of organic enrichment in both study areas. [ABSTRACT FROM AUTHOR]

Increasing employment of artificial barriers to combat coastal erosion is causing alterations of coastal ecosystems. Understanding their ecological functioning is key to planning management activities and minimising their negative impacts on the ecosystem. In this paper, changes in biodiversity and in functional traits of macrofaunal shallow communities were investigated throughout 4 years of study in the central Mediterranean. Biodiversity indices (S, d, H′) showed the highest mean values during in-operam phases (5.7, 1.99 and 2.07, respectively) whilst functional diversity (FDis) and functional redundancy (FDiv/H′) showed the highest mean values in ante-operam (4.34 and 2.44, respectively). The PERMANOVA showed differences both in species composition and functional traits between sampling periods. β-diversity was driven by the replacement of species over years. The non-indigenous polychaete Lumbrinerides neogesae, recorded for the first time during in-operam, supplied the highest differences between years (14.5%, SIMPER). During in and post-operam phases an increase of sub-surface deposit feeder, tolerant, and pioneer categories was recorded. When the classic taxonomic approach is combined with novel functional biodiversity attributes, a wide range of biota responses to a disturbance can be better described and the efficient mitigation solutions to minimize negative impacts of human activities proposed. [ABSTRACT FROM AUTHOR]

Abstract Estuaries are known to export huge quantities of terrigenous/riverine organic matter and nutrients to coastal areas, subsidizing food sources to their communities; however, this process is seldom investigated in complex multichannel delta-prodelta systems. Stable isotope analysis was used to investigate the contribution of organic sources originated from the Po River Delta, one of the widest deltaic wetlands in the northern Mediterranean Sea, to the diet of the nearby coastal macrobenthic consumers, and their influence on invertebrates' trophic structure and biomass. Following intense river flood events, macrofauna samples were collected in the prodelta area at increasing distance from the main river distributary mouth. Potential primary resources were collected within the delta and the prodelta areas. A terrestrial signal in the primary consumers' diet was evident as a shift in their δ13C, being this more 13C depleted near the main river distributary. The Bayesian mixing models indicated an important contribution of deltaic sources, in particular C4-grass detritus (25–57%), to primary consumers' diet, confirming a strong energetic link between delta and prodelta areas. Overall, most of the consumers' biomass were concentrated at sites close to the main distributary mouth, mainly as suspension and surface deposit feeders. A simplification of the macrobenthic community structure, accompanied by narrower transfer pathways was also evident at sites more distant from the main river distributary, in relation to changes in the quality of resources. Our data, although limited to winter season, suggest that during periods of low in situ productivity but high river flow energy, invertebrates are able to efficiently exploit terrigenous food sources, restraining the detrimental effect of increased turbidity and sedimentation. We conclude that riparian/wetland vegetation associated with river deltas can provide important food sources to marine primary consumers. These results furthermore highlight the need for integrated management and protection strategies of connected land-sea ecosystems. Graphical abstract Unlabelled Image Highlights • The study was carried out in the Po River Delta and the nearby coastal area. • Food sources' contributions to coastal macrobenthos' diets were assessed by stable isotopes. • Terrigenous isotopic signals decreased at increasing distance from the main river mouth. • Deltaic wetland detritus mainly contributed to primary consumers' diets. • Food sources quality shaped macrobenthos community structure along the river plume. [ABSTRACT FROM AUTHOR]

To assess the influence of river-derived material on the benthic ecosystem in the Po River prodelta area, we investigated the structural and functional features of macrofaunal invertebrates in 14 sites. Biodiversity, species composition, response and effect traits of the community were determined and related to the main sediment physical-chemical and nutritional features (biopolymeric carbon, BPC; protein to carbohydrate ratio, Prt/Cho ratio; phaeopigment to chlorophyll- a ratio, Phaeo/Chl- a), as well as contaminants. We found significant spatial differences in community structure and its functional expression between northern and southern stations, and between nearshore and offshore ones. The shallower stations located nearby the main river mouth displayed higher densities, diversity and functional redundancy compared to southern stations. The main discriminating factors for the community were the higher percentage of sand and Prt/Cho nearby the river mouth, and fine grain-size and high Phaeo/Chl- a at the southernmost and deeper stations. Contaminant concentrations did not seem to severely affect the macrofaunal community. Changes in community structure were due to the dominance of few species, which occurrence varied according to grain-size and organic matter quality that in turn were linked to the different magnitude of depositional loads in the investigated area. Focusing on response traits, we observed a clear influence of high loads nearby the main river mouth, through the dominance of sessile and tube-builder trait-categories at stations with a higher sand content. In contrast, we detected a major expression of burrowers and interface crawlers , and swimmers at southern and principally offshore muddy stations. Effect traits revealed that in the northern part of the prodelta prevailed suspension , surface deposit feeders and conveyor invertebrates that are, respectively, fundamental players in the benthic-pelagic coupling and elemental cycling within benthos. In the southern part , subsurface deposit feeder and biodiffuser organisms dominated. The latter are able to rework huge amounts of sediments also in the deepest layers, amplifying the elemental cycling and decomposition. In highly dynamic systems, as delta areas, the presence of invertebrates able to exploit different resources through bioturbation activities may enhance the functions of riverine costal ecosystems. • River-derived material influence on macrofaunal structural and functional features were assessed. • Response and effect traits were considered separately in the Biological Traits Analysis. • Changes in community structure were due to the dominance of few species, linked to sedimentology. • Functional attributes were highly related to dissimilar magnitude of depositional loads of the river. [ABSTRACT FROM AUTHOR]

This study represents the first example in which benthic heterotrophic and photoautotrophic microbial communities (prokaryotes and microphytobenthos-MPB, respectively) were simultaneously investigated. To explore how they synergistically respond to multiple natural and anthropogenic stressors, in the framework of the Project RITMARE four lagoons of the Po River Delta were sampled in May 2016: two with more marine features, i.e. Scardovari (SC) and Caleri (CL), and two more directly affected by the Po River flow, i.e. Canarin (CN) and Vallona-Marinetta (MV). The abundance and structure of benthic communities were related to physical-chemical parameters i.e. grain-size, total N, total organic C, stable C and N isotopes, and synthetic organic contaminants. Stations were gathered into three distinct groups (R ansosim = 0.540 p < 0.001) according to their different physical-chemical features: outer, inner-freshwater and inner-marine sites. Contamination levels did not seem to severely affect the microbial abundances that were overall stimulated by the combined effect of high organic and nutrient loads: prokaryotes up to +42% and MPB up to +93%. Bacteria and Archaea displayed high densities at sites directly influenced by the freshwater input and anthropogenically derived nitrogen. Delta- (30.8%), Alpha- (12.8%), Gamma- (11.8%) and Beta-Proteobacteria (7.1%) were the dominant classes at all sites. For both communities, a significant inter-lagoonal (among different lagoons) and intra-lagoonal (among stations within the same lagoon) pattern was highlighted by PERMANOVA. nMDS and SIMPER analyses revealed distinct assemblages in the inner and outer parts of the lagoons. We applied a novel functional approach based on diatom life modes. At inner and outer sites, different diatom living forms developed: epipsammic (on sand) nearby the lagoonal mouths, epipelic (on mud) at the innermost sites and non-benthic forms (planktonic, tychopelagic and epiphytic) at sites directly influenced by freshwater. Distance-based Linear Models further indicated that salinity, clay and temperature were the significant drivers of the prokaryotic spatial distribution whereas clay, PAHs, PCBs and salinity best explained the MPB structure. The dominance of non-benthic diatom life modes in the more polluted lagoon (CN) suggests a negative influence of contamination on the MPB structure. Two diatom keystone species likely contribute to restore the oxic gradient in sediments frequently exposed to anoxia, allowing the subsequent microbial aerobic degradation and the recolonization of higher trophic organisms. The capacity of re-oxygenation after anoxia has important ecological and economic implications in lagoons exploited for aquaculture. • We simultaneously studied Prokaryotes and MicroPhytoBenthos in four Po River lagoons. • Organic and nutrient loads stimulated Prokaryotes (+42%) and MPB (+93%) densities. • We found significant inter- and intra-lagoonal patterns for both Prokaryotes and MPB. • Salinity, clay and temperature best explained prokaryotic spatial distribution. • Clay, PAHs, PCBs and salinity were significant drivers of MPB composition. [ABSTRACT FROM AUTHOR]

The spectacular water outburst occurring semi-periodically when the ice-dam formed by the external front of the Perito Moreno glacier collapses, is one of the most attracting events in the UNESCO 'Parque Nacional Los Glaciares' of southern Patagonia. These occurrences have been documented since 1936. Instead, evidence of previous events has been only indirectly provided by dendrochronology analysis. Here we show for the first time radiocarbon-dated sediment cores collected within a small inlet of Brazo Sur, that is, the southern arm of Lago Argentino that record ice-dammings in the Little Ice Age, at 324–266 cal yrs BP, as measured on a vegetal fragment sampled at ca. 14 cm from the top of a core. A common characteristic of the three sediment cores is the abrupt change in the stratigraphic record found at variable depths of 14–18 cm from the top of the cores. This change is marked by a hiatus spanning ca. 3200 years, separating planar-laminated sediments below from an alternation of erosional and depositional events above it, indicating recurring high-energy conditions generated by the emptying of the lake basin. In addition, we observed significant changes in the abundance of environmental indicators as testate amoebae below and above the hiatus. These well-preserved stratigraphic records highlight the key role of glaciolacustine deposits in reconstructing the glacial dynamics and palaeoclimate evolution of a glaciated region. [ABSTRACT FROM AUTHOR]

The effects of mangrove vegetation on functional features of crustacean assemblages were investigated using the Biological Traits Analysis (BTA). The study was carried out at four major sites in the arid mangrove ecosystem of the Persian Gulf and Gulf of Oman. Samples of Crustacea and associated environmental variables were taken seasonally (February 2018 and June 2019) from two habitats: a vegetated area with both mangrove trees and pneumatophores, and an adjacent mudflat. In each site, functional traits for the species were assigned using seven categories based on bioturbation, adult mobility, feeding habits and life-strategy traits. The results showed that the crabs (i.e., Opusia indica , Nasima dotilliformis and Ilyoplax frater) were widely distributed across all sites and habitats. The vegetated habitats supported higher taxonomic diversity than the mudflats, which highlights the importance of mangrove structural complexity for crustacean assemblages. Species inhabiting vegetated habitats were characterized by stronger presence of conveyor building species, detritivore, predator, grazer, lecithotrophic larval development, body size of 50–100 mm, and swimmer trait modalities. While, mudflat habitat enhanced the occurrences of surface deposit feeder, planktotrophic larval development, body size of <5 mm, and life span of 2–5 years. The results of our study showed that taxonomic diversity increased from the mudflats to the mangrove vegetated habitats. However, functional diversity did not differ between habitats. The significant differences in species and functional trait composition were observed between vegetated habitats and adjacent mudflats, stressing that different habitats may harbor different species and trait sets, likely as a result of habitat complexity. The use of taxonomic and functional attributes generate complementary information that can helps us to reach more efficient conclusions in terms of biodiversity conservation and ecosystem functionality in mangrove ecosystems. • The study was carried out at arid mangroves located at the northernmost latitudinal limit of mangroves in the Indian Ocean. • Taxonomic diversity increased from the mudflats to the mangroves. However, functional diversity did not differ between habitats. • Patterns in species composition among sites, habitats and seasons were consistent with patterns in trait composition. • The conservation efforts of mangroves should consider the value of mudflats and prioritize connectivity between habitats. [ABSTRACT FROM AUTHOR]