Desde microorganismos a la macrofauna: un estudio comparativo de las comunidades bentónicas profundas y su respuesta a las variables ambientales a lo largo del talud de Malta (mar Jónico)

A comparative study for abundance, biomass and diversity was carried out for the prokaryote, meiofauna and macrofauna communities at three depth stations (1200, 1800 and 2100 m) along the Malta Escarpment (Mediterranean Sea). Our investigation showed a two-fold increase with depth in prokaryote abundance; the contribution of prokaryote biomass to the total benthic biomass was predominant at all depths. Bacteria were the dominant prokaryote component and Archaea formed a considerable fraction (20%-30%) of the prokaryote assemblages. The meio- and macrofauna abundances and meiofauna biomass did not decrease significantly with depth but macrofauna biomass did. The α diversity did not follow a clear bathymetric trend for both nematode and macrofauna species. Probably because of the large number of eurybathic nematode genera, nor did the turnover diversity in nematode composition change down the depth gradient. Conversely, for the macrofauna there was a perceptible change in community composition between the shallowest station and the two deeper stations. Food availability affected only the macrobenthic component. The increase in the prokaryote organisms with depth and the dominance of nematodes and macrofauna deposit feeders suggest active grazing by the two benthic components on microbes. This would transfer energy to the higher trophic levels through the microbial compartment.Se llevó a cabo un estudio comparativo de las comunidades de procariotas, meiofauna y macrofauna sobre la abundancia, biomasa y diversidad. Fue realizado en tres estaciones en varias profundidades (1200, 1800 y 2100 m) a lo largo del talud de Malta (mar Mediterráneo). Nuestra investigación muestra que, aumentando la profundidad, la abundancia de procariotas se duplica. La contribución de la biomasa procariota al total de la biomasa bentónica predominó en todas las profundidades. Las bacterias eran la fracción procariota dominante y junto con los Archaea representaban al 20-30% del total de procariotas. Por otra parte la abundancia de la meiofauna y macrofauna y la biomasa de la meiofauna no disminuían significativamente con la profundidad, mientras que la biomasa de la macrofauna sí lo hacía. La diversidad α no siguió una tendencia batimétrica muy clara para las especies de los nematodos y macrofauna. Probablemente debido a la gran abundancia de géneros de nematodos eurybatiales, la tasa derenovación de la diversidad en la composición de nematodos tampoco cambió por el gradiente de profundidad. En cambio, para la macrofauna hubo un cambio apreciable en la composición de la comunidad entre la estación más superficial y las dos estaciones más profundas. La disponibilidad de alimentos afectó sólo al componente macrobentónico. El aumento con la profundidad de los organismos procariotas, el dominio de los nematodos y la macrofauna que se alimenta de los materiales depositados sugieren un medio activo para los dos componentes bentónicos microbianos. Esto daría lugar a una transferencia de energía a niveles tróficos superiores a través del compartimento microbiano

Multi-benthic size approach to unveil different environmental conditions in a Mediterranean harbor area (Ancona, Adriatic Sea, Italy)

Harbors are hubs of human activity and are subject to the continuous discharge and release of industrial, agricultural, and municipal waste and contaminants. Benthic organisms are largely known to reflect environmental conditions they live in. Despite meio- and macrofauna interacting within the benthic system, they are ecologically distinct components of the benthos and as such may not necessarily respond to environmental conditions and/or disturbances in the same way. However, in a few field studies the spatial patterns of meio- and macrofauna have been simultaneously compared. In the present study, we assess the response and patterns in the abundance, diversity, and distribution of the two benthic size classes to the different environmental conditions they live in (i.e., sediment concentrations of selected trace metals and polycyclic aromatic hydrocarbons (PAHs); organic matter contents and grain size) characterizing the Ancona Harbor (Adriatic Sea). Meio- and macrofauna provided partially similar types of information depending on the indices used (univariate measures or community structure/species composition) and the different ‘response-to-stress’. The community structure (i.e., taxa composition) of both benthic size components clearly showed differences among sampling stations located from inside to outside the harbor, reflecting the marked environmental heterogeneity and disturbance typically characterizing these systems. Notwithstanding, the univariate measures (i.e., meio- and macrofauna total abundance, diversity indices and equitability) didn’t show similar spatial patterns. Meiofauna were likely to be more sensitive to the effects of environmental features and contaminants than macrofauna. Overall, trace metals and PAHs affected the community composition of the two benthic components, but only the meiofauna abundance and diversity were related to the environmental variables considered (i.e., quantity and quality oforganic matter). Our results pinpoint the importance of studying both meio- and macrofauna communities, which could provide greater insight into the processes affecting the investigated area and reveal different aspects of the benthic ecosystems in response to harbor conditions

. Ecological role and phylogenetic position of a new habitat-forming species (Canalipalpata, Sabellidae) from the Mediterranean mesophotic soft-bottoms

This study presents a description of Bispira riccardi sp. nov., a new habitat-forming sabellid polychaete from the mesophotic NW Mediterranean Sea. Individuals, up to 20 cm long, show a peculiar morphology of radioles, thoracic uncini, companion chaetae and ventral shield of the collar. The phylogenetic position of this new taxon in the genus Bispira has been validated using nuclear (18S rRNA) and mitochondrial (COI) markers. Aggregations of B. riccardi sp. nov. were found by ROV on horizontal muddy bottoms between 56 and 85 m, in areas subjected to high trophic inputs. Patches are fragmented and dense (up to 943 individuals m 2) probably accounting for various hectares. A 5-days continuous monitoring, carried out using an autonomous lander, revealed that the contraction of the branchial crown was positively affected by temperature and current, rapidly responding to meteorological events. The filtering activity and high density of these fields suggest a considerable impact on the pelagic-benthic coupling and the amount of organic matter in the sediments. Indeed, meiofaunal abundance and diversity within the aggregations resulted significantly higher than in outer stations. These findings highlight the undisclosed potential of the deep Mediterranean Sea for sabellid diversity and their importance as habitat-forming species on mesophotic soft bottoms

Assessment of spatio-temporal variability of faecal pollution along coastal waters during and after rainfall events

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Manini, E., Baldrighi, E., Ricci, F., Grilli, F., Giovannelli, D., Intoccia, M., Casabianca, S., Capellacci, S., Marinchel, N., Penna, P., Moro, F., Campanelli, A., Cordone, A., Correggia, M., Bastoni, D., Bolognini, L., Marini, M., & Penna, A. Assessment of spatio-temporal variability of faecal pollution along coastal waters during and after rainfall events. Water, 14(3), (2022): 502, https://doi.org/10.3390/w14030502.More than 80% of wastewaters are discharged into rivers or seas, with a negative impact on water quality along the coast due to the presence of potential pathogens of faecal origin. Escherichia coli and enterococci are important indicators to assess, monitor, and predict microbial water quality in natural ecosystems. During rainfall events, the amount of wastewater delivered to rivers and coastal systems is increased dramatically. This study implements measures capable of monitoring the pathways of wastewater discharge to rivers and the transport of faecal bacteria to the coastal area during and following extreme rainfall events. Spatio-temporal variability of faecal microorganisms and their relationship with environmental variables and sewage outflow in an area located in the western Adriatic coast (Fano, Italy) was monitored. The daily monitoring during the rainy events was carried out for two summer seasons, for a total of five sampling periods. These results highlight that faecal microbial contaminations were related to rainy events with a high flow of wastewater, with recovery times for the microbiological indicators varying between 24 and 72 h and influenced by a dynamic dispersion. The positive correlation between ammonium and faecal bacteria at the Arzilla River and the consequences in seawater can provide a theoretical basis for controlling ammonium levels in rivers as a proxy to monitor the potential risk of bathing waters pathogen pollution.This research was funded by WATERCARE project (Water management solutions for reducing microbial environment impact in coastal areas, project ID 10044130, https://www.italy-croatia.eu/web/watercare, accessed on 17 October 2021) funded by the European Union under the Interreg Italy–Croatia CBC Programme

A threefold perspective on the role of a pockmark in benthic faunal communities and biodiversity patterns

Pockmarks are circular-shaped depressions that increase seabed heterogeneity and are characterized by discontinuous fluid emissions. To understand how environmental conditions of pockmarks affect the structure of macroand meiofauna, we investigated two sites in a pockmark field in the northwestern Madagascar margin. In a comparative approach, we explored the community structure of the dominant taxa (Polychaeta, Nematoda and hyaline foraminifera) in each component (macro-, metazoan meiofauna and foraminifera, respectively). The investigated active pockmark showed approximately two times higher meiofauna abundance compared to in a site away from another pockmark field, but macrofauna showed the opposite trend, with almost half density at the pockmark site. However, at both sites, macroand meiofauna showed higher richness and abundance values in the top well-oxygenated layers of the sediment than in the underlaying ones. Polychaeta and Nematoda showed lower richness in the pockmark, opposed to hyaline foraminiferans, but lower evenness in the pockmark was found for the three groups. The detection of gas flares in the water column attests of the recent activity within the pockmark. High amount of sulfur-bearing minerals (mainly pyrite) evidences a production of dissolved free sulfides (not detected at the time of sampling) by sulfate reduction process driven by organic matter degradation and anaerobic oxidation of methane. Furthermore, recent increase in sedimentation rates in the past 70 years and organic matter inputs could have led to higher organic matter degradation rates resulting in reduced conditions and a high oxygen consumption. All this together seem to act as key factors in the determination of variation in richness, abundance and community composition of macrofauna and meiofauna. Additionally, some taxa seem to be more tolerant to these extreme conditions, such as species belonging to the Nematoda genus Desmodora and the phylum Kinorhyncha, which are highly abundant in the pockmark, and hence, may be considered as potential bioindicators of pockmark activity in this area. Further studies are required for a better assessment

Status of faecal pollution in ports: A basin-wide investigation in the Adriatic Sea

Ports are subject to a variety of anthropogenic impacts, and there is mounting evidence of faecal contamination through several routes. Yet, little is known about pollution in ports by faecal indicator bacteria (FIB). FIB spatio-temporal dynamics were assessed in 12 ports of the Adriatic Sea, a semi-enclosed basin under strong anthropogenic pressure, and their relationships with environmental variables were explored to gain insight into pollution sources. FIB were abundant in ports, often more so than in adjacent areas ; their abundance patterns were related to salinity, oxygen, and nutrient levels. In addition, a molecular method, quantitative (q)PCR, was used to quantify FIB. qPCR enabled faster FIB determination and water quality monitoring that culture-based methods. These data provide robust baseline evidence of faecal contamination in ports and can be used to improve the management of routine port activities (dredging and ballast water exchange), having potential to spread pathogens in the sea

Macrofauna biodiversity and ecosystem functioning in the deep-sea. Mediterranean sediments: analysis at different spatial scales

L’obiettivo principale della mia tesi di dottorato è stato quello di investigare le relazioni tra la biodiversità della macrofauna profonda del Mar Mediterraneo ed il funzionamento eco sistemico (BEF). Tale studio è stato svolto considerando differenti scale spaziali d’indagine, i) da centinaia di metri a diversi chilometri; ii) centinaia di chilometri e iii) migliaia di chilometri, e comprendendo sistemi di scarpata continentale con caratteristiche ambientali differenti. Sono state testate le seguenti ipotesi: 1) vi è una relazione significativa tra la biodiversità della macrofauna profonda ed il funzionamento eco sistemico; 2) la forma e l’intensità di tale relazione cambia al variare della scala spaziale considerata e dal sistema investigato. Lo studio è stato condotto con un duplice approccio, da prima investigando la variabilità della macrofauna a differenti scale spaziali e poi testando la presenza delle relazioni tra biodiversità e funzionamento eco sistemico. Su larga scala spaziale (i.e. migliaia di chilometri; intero bacino del Mediterraneo) abbondanza, biomassa e ricchezza in specie del macrobenthos mostravano una maggiore variabilità con la longitudine rispetto alla profondità, con valori inferiori caratterizzanti i sedimenti del Mediterraneo orientale profondo. Differenze significative nella composizione in specie (turnover diversità) erano emerse non solo tra bacini, ma anche tra siti all’interno dello stesso bacino e tra stazioni a differenti profondità. La disponibilità alimentare e le differenti caratteristiche granulometriche dei sedimenti influenzavano la variabilità della macrofauna sia in termini di abbondanza e biomassa che di composizione in specie. Su scala spaziale minore (i.e. da centinaia di metri fino a diversi chilometri; singola area di scarpata), la macrofauna mostrava maggiore variabilità in termini di abbondanza e biomassa con l’aumentare della profondità piuttosto che tra stazioni collocate alla medesima profondità e distanti tra loro diverse centinaia di metri. Considerando però la composizione in specie (turnover diversità), differenze emergevano anche tra stazioni alla medesima profondità fino a 1500 metri. Al di sotto di tale profondità le comunità divenivano omogenee. Considerando una scala spaziale di diverse centinaia di chilometri (i.e. confronto tra due sistemi di scarpata nel Mediterraneo occidentale), differenze significative tra le due aree di scarpata emergevano non solo intermini di abbondanza e biomassa, ma anche in termini di ricchezza e composizione in specie della macrofauna. Lungo entrambi i sistemi di scarpata, la composizione in specie variava con la profondità fino a 1800 metri, al di sotto dei quali le comunità divenivano omogenee. Studi precedenti su scala globale hanno evidenziato una relazione esponenziale e positiva tra la biodiversità dei nematodi profondi ed il funzionamento ed efficienza eco sistemici, facendo ipotizzare una presenza di relazioni mutualistiche tra organismi che compongono le comunità bentoniche profonde. Anche in questo studio sono emerse relazioni prevalentemente esponenziali e positive tra la biodiversità della macrofauna del Mediterraneo ed il funzionamento ed efficienza eco sistemici su macroscala (migliaia di kilometri). La biodiversità era inoltre legata positivamente anche alla diversità funzionale. Tali risultati mostrano come comunità macrobentoniche maggiormente diversificate possano sostenere non solo livelli di funzionamento ed efficienza eco sistemici più elevati, ma anche una diversità funzionale maggiore in grado di promuovere anch’essa un miglior funzionamento dell’ecosistema. Su larga scala spaziale è possibile quindi ipotizzare la presenza di relazioni mutualistiche tra le comunità macrobentoniche del Mediterraneo profondo. Quando le relazioni BEF venivano testate considerando una scala spaziale minore (singola area di scarpata a nord della Sardegna; da centinaia di metri fino a diversi chilometri), la maggior parte delle relazioni emerse su macroscala non risultavano più significative. Piuttosto erano il risultato dell’azione esercitata dalle variabili ambientali, le quali guidavano l’effetto della diversità sul funzionamento eco sistemico. Considerando una scala spaziale di diverse centinaia di chilometri (due sistemi di scarpata nel bacino occidentale), emergevano di nuovo relazioni esponenziali positive tra biodiversità e funzionamento ed efficienza eco sistemici. Ma quando le relazioni BEF venivano testate considerando i due sistemi di scarpata separatamente, differenti erano le risposte. Mentre lungo la scarpata a largo delle Baleari persistevano relazioni BEF significative, anche considerando diversi indicatori di funzionamento ed efficienza eco sistemici, lungo la scarpata Sarda le relazioni erano nuovamente guidate dall’effetto delle variabili ambientali. Le relazioni BEF lungo quest’ultima non erano per cui causali. Ciò ha portato a pensare che maggiore la scala spaziale considerata, maggiore la possibilità di trovare relazioni BEF significative. È possibile pertanto concludere che la forma, ma soprattutto l’intensità (= la significatività) delle relazioni BEF variano al variare della scala spaziale considerata e delle condizioni ambientali, almeno per quanto riguarda la componente macrobentonica profonda del Mediterraneo. Quando differenti scale spaziali e sistemi (es. aree di scarpata) vengono investigati, differenti sono le comunità bentoniche coinvolte così come i tratti funzionali da esse rappresentati. È perciò logico ipotizzare che differenti tratti funzionali inclusi e/o esclusi ogni qual volta vengano considerate differenti scale spaziali e sistemi possano influenzare il risultato delle relazioni BEF testate. I risultati emersi da tale studio mostrano come in generale la biodiversità della macrofauna profonda possa influenzare positivamente il funzionamento eco sistemico, lasciando quindi presupporre la presenza di relazioni mutualistiche tra le componenti delle comunità macrobentoniche. Tuttavia tali interazioni, cosi come l’effetto della biodiversità sul funzionamento eco sistemico, sono altamente sensibili alla scale spaziale considerata ogni volta e quindi al sistema studiato (es. area di scarpata; bacino)

Meiofauna communities' response to an anthropogenic pressure: The case study of green macroalgal bloom on sandy beach in Brittany

International audienceOpen sandy beaches support key ecological functions and a distinctive biodiversity, but are threatened by an increasing anthropogenic pressure. Among these threats is the occurrence of green tides of Ulva spp., expression of the eutrophication phenomenon. Our study aimed at determining the impact of green macroalgal accumulations on benthic meiofauna inhabiting two macrotidal sandy beaches of Brittany: Saint Nic (impacted) and Anse de Dinan (unimpacted). The presence of Ulva enhanced total meiofaunal abundance and nematode functional diversity when compared to a state free from macroalgal mats. The stranded Ulva supported high values of meiofaunal beta-diversity as well. This unexpected response was likely due to the highly dynamic nature of open sandy beaches that prevents O-2 depletion within sediments. Natural seasonal changes in meiofaunal biomass and composition were also evident at both beaches and changes in environmental features, apart from eutrophication alone, do drive the variability in meiofaunal biomass and nematodes diversity