Is the meiofauna a good indicator for climate change and anthropogenic impacts?

Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research

Distribution of recent foraminifera in high energy environment from the Strait of Bonifacio, Sardinia (Italy)

The ecology of benthic foraminifera is related to the physical and chemical conditions of the bottom environment. Since foraminifera have a short life cycle and big density, they react quickly to environmental changes and can be used as bio-indicators for ecological investigations. This is true for both short and long time-scales and for various marine ecosystems (impacted by pollution, for instance). The understanding of the impact of natural parameters on benthic foraminifera distribution is a obliged prerequisite, before describing anthropogenic impact. More concrete knowledge about the various environmental parameters and their connected benthic foraminiferal community response is presently needed. A better understanding of the mechanisms that determine the distribution of associations in natural environments will allow promoting the use of foraminifera in environmental monitoring to decision-makers and governmental bodies. In this study, we investigate the relationships between the benthic foraminifera (species composition, population density and diversity, assemblage structure and spatial distribution pattern) and environmental parameters (depth, grain size, organic matter). These investigations are based on 31 samples collected in the Strait of Bonifacio. On the basis of a preliminary results, the spatial distribution of the foraminiferal assemblages appears to be strongly correlated to high hydrodynamic energy, sediments grain-size, organic matter content and bathymetry. These natural parameters appear to drive natural benthic changes that should be taken in account before studying polluted coastal environments

Environmental parameters constraint on distribution of benthic foraminifera in the Strait of Bonifacio (Mediterranean Sea)

The Strait of Bonifacio is located between the Isles of Sardinia and Corsica (Mediterranean Sea), its maximum depth is about 100 m. The Strait is the exchange zone between the waters of the Tyrrhenian and Ligurian-Provençal basins and is strongly affected by high current action. Benthic foraminifera were identified in 31 samples collected during an oceanographic cruise (“Bocche 2003” - P.I.C Interreg III Project) that provided new geomorphological and sedimentological data on the western continental shelf of the Strait of Bonifacio. Several biotic parameters were calculated (species diversity, density, Fisher α index, Shannon-Weaver index, and Dominance) and multivariate analyses (Cluster Analysis, Principal Component Analysis and Canonical Correspondence Analysis) were performed to identify foraminiferal assemblages in the context of environmental parameters. Strong current, bathymetry, grain-size, organic matter and food availability are the main factors exerting control on the spatial distribution of benthic foraminifera in the Strait of Bonifacio. Three groups of assemblages were differentiated according to several sampling sites, which varied mainly due to degrees of energy. The first group included the shallowest station, close to the islands of Corsica and Sardinia, while the two other were typical of high-energy environments and were localized in the central area of the Strait. Cluster C concerns those located at a central position, while cluster B includes those in a more lateral position at the deepest part of the Strait. Elphidium crispum, Eponides concameratus and Textularia agglutinans appeared to be the more adapted species in this high-hydrodynamic system. The dominance of the epibenthic foraminifera (e.g. Lobatula lobatula and Planorbulina mediterranensis), permanently attached to sea grasses (Posidonia oceanic) and algae has been related to both the greater current velocities in the sampled area. The occurrences of Miliolinella subrotunda, Neoconorbina nitida, Quinqueloculina stelligera, Rosalina globularis, R. vilardeboana and Sigmoilinita costata appear to be closely related to the abundance of organic carbon and higher C/N ratios. The distribution of S. sagittula appear closely linked with bathymetry. Interaction between multiproxy ecological factors (oxygen, food, toxic substances, biological interactions, transport, light penetration, turbidity, etc.) characterize peculiar microenvironments in the sediment-water interface, allowing different species to occupy different niches within a relatively small area. A detailed understanding of environmental parameters that influence benthic foraminifera distribution in natural systems is a necessary prerequisite for the use of foraminifera as useful tools for ecological and environmental interpretations

Benthic foraminifera in transitional environments in the English Channel and the southern North Sea: A proxy for regional-scale environmental and paleo-environmental characterisations

On the basis of the available databases including 700 sampling stations from subtidal to salt marsh areas, the purpose of this paper is to synthesise the regional distribution of living benthic foraminifera in transitional environments along the English Channel and southern North Sea. Indicator species analyses assign 37 foraminiferal taxa to high salt marsh, middle salt marsh, low salt marsh, tidal flat, tidal channel, and subtidal environmental units. Species are indicator of a single unit (e.g., Elphidium gunteri for tidal flat) up to four units (e.g., Haynesina germanica from tidal flat to middle marsh). The outcomes of the present study enhance future high-resolution paleo-environmental interpretations based on benthic foraminifera in transitional environments

Meiobenthos and free-living nematodes as tools for biomonitoring environments affected by riverine impact

none7sìThe effects of the human impact on the coastal environments and relative biota can be different and even greater than those derived by natural fluctuations. The major disturbance causes in the coastal systems are rivers that may be important sources of nutrients and pollutants, particularly in a semi-closed basin such as the Adriatic Sea. In this context, we investigated the distribution of both meiobenthic and nematode assemblages in the Central Adriatic Sea to evaluate whether and how they are influenced by riverine discharges and which faunal descriptors are the most effective in detecting this type of stress. On the basis of our results, the disturbance effects in the studied area might be caused by both local streams and Po plume, and even if the latter might be considered of lesser extent, it is worthy to note its real impact at a short distance from the coastline. Meiobenthic assemblage structure appears as a good tool for detecting short-term responses of the benthic domain, whereas nematode assemblages seem more useful for defining long-term responses. Accordingly, the former highlighted from poor to sufficient ecological quality status (EQS) of this area, whereas the latter from moderate to bad EQS. Life strategy traits prove to be the most informative faunal descriptor due to their high correspondence with the environmental variables and particularly with this type of disturbance.openSemprucci, F; Frontalini, F; Sbrocca, C; du Châtelet, E Armynot; Bout-Roumazeilles, V; Coccioni, R; Balsamo, MSemprucci, Federica; Frontalini, Fabrizio; Sbrocca, Claudia; du Châtelet, E. Armynot; Bout Roumazeilles, V; Coccioni, Rodolfo; Balsamo, Mari

Multidisciplinary study to monitor consequences of pollution on intertidal benthic ecosystems (Hauts de France, English Channel, France): Comparison with natural areas

The intertidal areas of the Hauts-de-France (English Channel - France) stand out for the occurrence of fragile ecosystems that are exposed to natural and human-induced stress. Over the last two centuries, the northern part of this region has experienced a strong human pressure, with the settlement of numerous activities (i.e., metallurgic factories, harbors, embankments). On the contrary, the southern part includes mostly natural areas. The whole region is influenced by a macrotidal regime. A multidisciplinary approach based on sedimentological (grain-size), geochemical (trace metals, biomarkers) and biological (foraminifera) proxies was used to unravel the contrasting environmental conditions in the Hauts-de-France. Three foraminiferal-types communities, which reflect different ecological characteristics at regional scale, were identified: 1) estuarine macrotidal assemblages (Haynesina germanica associated to Elphidiidae) in low impacted estuaries; 2) industrial-perturbed assemblages (H. germanica and Cribroelphidium excavatum) in harbor areas; and 3) infaunal-dominant assemblages (Bolivina variabilis and B. pseudoplicata) in embankment areas. The outcomes of this study show that a multiproxy procedure needs to be adopted for properly characterizing intertidal ecosystems, where human impacts and natural stresses overlap and are hard to disentangle

Biodiversity and distribution of the meiofaunal community in the reef slopes of the Maldivian archipelago (Indian Ocean)

Marine biologists have progressively increased their consciousness of the importance of meiofauna for the benthic domain in both temperate and tropical regions. After the 1998 bleaching, Maldivian reefs (Indian Ocean) have been regarded as a vulnerable ecosystem that must be carefully monitored. Accordingly, an extensive investigation of meiofaunal distribution in the reef slopes of the Maldivian archipelago has been carried out, taking into account geographical position, type of habitat (inner vs. outer slope), inclination and depth gradient. Twenty-four taxa revealed the highest meiofaunal richness ever found in Maldivian reefs. Interestingly, Thermosbenacea and Syncarida were identified, which are two taxa that have only recently been documented in the marine ecosystem. Chaetognatha were also present, which is a group that was only considered to be planktonic until 2000, when they were also discovered in the benthos. The type of habitat, affected by different hydrodynamic conditions, was the main factor influencing the meiofaunal community's structure and diversity. In detail, the outer reefs were characterized by the highest level of diversity, confirming previous observations on the rate of coral reef growth and vitality and underlining the greater vulnerability of the inner slopes. In contrast, depth only significantly affected the community structure, but not its density or diversity. Accordingly, community structure seems to be more sensitive than abundance and diversity indices when it comes to detecting depth gradients. The 10° inclination of the inner slopes revealed the most different community structure and the greatest dominance of nematodes, leading to the lowest diversity levels

Biodiversity trends of the meiofauna and foraminifera assemblages of Lake Varano (southern Italy)

In this study, the meiofaunal diversity in Lake Varano (southern Italy) is investigated in detail. Using a statistical approach, these data were coupled with the physicochemical parameters of the bottom water and the sediment characteristics in order to understand the factors influencing meiofaunal biodiversity distribution. The lake is selectively influenced by different factors, namely: organic matter and grain-size, as well as water salinity. Although these assemblages appear to be poorly diversified, the diversity index values are similar to those generally reported in other transitional environments. Relatively higher values of both meiofaunal and benthic foraminiferal diversity were found in front of the Capoiale channel and in the inner part of the lake. The meiofaunal assemblages are mainly dominated by nematodes, copepods, and turbellarians. The benthic foraminiferal assemblages comprise 18 taxa and are mainly represented by calcareous forms, suggesting a relatively low degree of confinement and, consequently, moderately restricted conditions. These assemblages are comparable to the Ammonia assemblages with Haynesina germanica that are characteristic of lagoons along the Mediterranean coasts. On the basis of these findings, coupled with the biotic data, the lake can be regarded as an oligomesotrophic environment