Checklist of benthic macroinvertebrates of the Lago Pratignano ( northern Apennines , Italy ) : an extremely rich ecosystem

A checklist of the macroinvertebrates fauna of the Lago Pratignano is presented here. The Lago Pratignano is a small, natural water body of the high (1,307 m above sea level) Northern Apennines, Italy. It represents an important site for the conservation of endangered flora and amphibians, and its importance for the conservation of the macroinvertebrate fauna is highlighted. The 82 taxa recorded make it an extremely rich habitat. The most represented group was Diptera, with 31 taxa, followed by Coleoptera, with nine, and Oligochaeta and Arachnida, each with eight taxa. Other groups are present in lower numbers. Despite the scant attention to theP study of the macroinvertebrates of small lentic habitats in the Northern Apennines, their importance for the conservation of the invertebrate fauna and the high contribution they give to the biodiversity is highlighted here.


INTRODUCTION
Ponds offer a wide variety of habitats (Davies et al. 2008), represent important hotspots for biodiversity (EPCN 2008), and compared to all other water body types, they support more unique and rare species (Williams et al. 2004).These ecosystems contribute significantly to biological diversity (Ruggiero et al. 2005); altogether, they host a larger number of species than rivers, lakes or streams (Williams et al. 2004).Despite their high ecological value, they are nowadays the most vulnerable and threatened water ecosystems, yet they still receive scant attention in political and legislative spheres (EPCN 2008).The macroinvertebrate community contributes to this biodiversity with its species playing essential roles in different key processes of these ecosystems (Reice and Wohlenberg 1993).Therefore, they have been chosen by the Directive 2000/60/EC (Water Framework Directive) as indicators of the ecological status of waterbodies (CEC 2005).
Local and national authorities protect most of the mountain areas along the Apennines in Italy, but the few natural ponds are still under threat even if they are within natural parks (Solimini et al. 2008).Some information on the macrozoobethic community of small water bodies is present for Europe (Boix et al. 2001;Sahuquillo et al. 2007;Oertli et al. 2008;Céréghino et al. 2012;Guareschi et al. 2012;Novikmec et al. 2015).In Italy, there are data for alpine mountains ponds (Boggero et al. 2005;Boggero and Lencioni 2006;Füreder et al. 2006;Maiolini et al. 2006;Steingruber et al. 2013) and for lowland ponds (Solimini et al. 2005;Della Bella et al. 2005;Della Bella and Mancini 2009).However, only scattered information is available for the central Apennines Mountains (Solimini et al. 2008) and none for the northern and southern parts.The northern part of the Apennines is located between two different phytogeographic regions: the Euro-Siberian region to the north and the Mediterranean region to the south (Alessandrini et al. 2003).This area at the boundary between two different phytogeographic regions should be investigated: high-altitude aquatic ecosystems may be more sensitive to global climate change than aquatic ecosystems at lower elevations (Theurillat and Guisan 2001) and could be more quickly affected by climate change.
As at the national level, data on these water bodies in the province of Modena are scattered.There are several publications on the macroinvertebrates of the lowlands (Ansaloni and Prevedelli 2008;Ansaloni et al. 2009Ansaloni et al. , 2010Ansaloni et al. , 2014) ) but none on the macroinvertebrates of the high Apennines.Only studies on plankton (Moroni 1962), vegetation (Accorsi et al. 1981), amphibians (Sala et al. 1996), physico-chemical parameters of the waters (Boraldi et al. 2005) and single groups of macroinvertebrates (Rocchi 2009) are available.
The importance of the Lago Pratignano for the morphometric and geological information of the area can be found in Bertacchini et al. (1999).According to Kottek et al. (2006), the climate of the area of the Lago Pratignano is warm temperate and fully humid with warm summers (Cfb type following the Köppen-Geiger climate classification).Different vegetation typologies are present within the pond (Figure 3).In the southern part, where the pond is deepest, the vegetation is characterized by the presence of the hydrophytes: Potamogeton natans, P. oblongus, P. trichoides and Myriophyllum spicatum.Near the shore, where the depth is less than 1 m, Potamogeton sp., Sparganium emersum and Ranunculus trichophyllus subsp.trichophyllus are present.The vegetation in the shallows (water 0.8 -1 m deep) is characterized by richness and the peculiarity at a regional scale level of its flora and fauna has already been highlighted by Accorsi et al. (1982), Mazzoldi et al. (2009) and Alessandrini et al. (2010).However, no studies on the macroinvertebrate community of this pond have been published.The aim of this paper is to highlight the richness of the macroinvervetebrate community in this pond, to show seasonal variations, and to create a baseline of information for the conservation and the possible future management of this valuable habitat.Furthermore, this study adds to the basic knowledge on these habitats, which are still barely known in the northern Apennines.

Study site
The Lago Pratignano (44°12ʹ39ʺ N, 010°43ʹ30ʺ E) is a small, high-altitude water body located at 1,307 m above sea level within the Regional Park of the High Modena Appenines (Parco Regionale dell'Alto Appennino Modenese, Northen Apennines, Italy) and the SCI-SPA IT4040001 "Cimone, Libro Aperto, Lago di Pratignano" of the Natura 2000 network (Figure 1).The Lago Pratignano has a total surface area of about 50,000 m 2 ; the mean depth is about 2 m and the maximum depth is 4.5 m.Through the year, the water level varies by about 0.4 m.Considering its dimensions and its mean depth, it can be defined as a pond according to the European Pond Conservation Network (EPCN 2008).The pond has a semi-triangular outline that is elongated on a northsouth axis.One small tributary flows into the pond at its southern edge and there is no outflow (Figure 2).The presence of water is guaranteed by a broad catchment basin, by the permeability of the surrounding ground and by the presence of a thick covering of ice from December through to the end of March to April.Other  concentric belts of Menyanthes trifoliata, Carex rostrata and Carex versicaria (from deepest to shallow water).At the margins, a discontinuous formation of Alopercurus aequalis, Eleocharis palustris, Oenanthe acquatica and Hottonia palustris is present.Finally, there is a peat bog and associated vegetation that is located at the north end of the pond where, among Menyanthes trifoliata and Phragmites australis, there is a wide floating pillow of Sphagnum cuspidatum and Sphagnum sp.It is there that Drosera rotundifolia, Utricularia australis and U. vulgaris (Alessandrini et al. 2010), three interesting species for the Italian flora, can be found.

Data collection
The sampling of macrozoobenthos was performed in spring, summer and autumn 1999 and in summer 2006.All ice-free seasons were sampled to detect possible differences and to record all the biodiversity present in the pond.No samples were taken during winter because of ice on the pond.The summer sampling was repeated in 2006 as it resulted that the biodiversity was richest in that season after the first campaign of 1999.Five sampling sites (St. 1,St. 2,St. 3,St. 4 and St. 5) were selected to cover all the different substrates and littoral vegetation types (Figure 2).Station 4 was sampled only in spring 1999 because this area dried during the summer of 1999 and 2006 and autumn of 1999; station 2 was not sampled in autumn of 1999 for the same reason.The relative dominance of the different substrates and littoral vegetation types were considered so as to equally distribute the sampling effort over all habitat types.No quantitative samples could be taken because of the variability of the substrate (from mud to sand and from organic deposits to submerged grassland) and because of the presence of the submerged vegetation that could be sampled only with a dip net.
At each sampling site the main physico-chemical parameters were recorded seasonally.Data included water temperature, pH, conductivity, dissolved oxygen and percent oxygen saturation that were recorded by a portable instrument.
Zoobenthos samples were taken from the littoral zone to a maximum depth of 0.5 m using a dip net (25 × 25 cm wide; 250 μm mesh size) according to Storey et al. (1991).Collections were made under permit (Prot.n. 677) from the Director of the Regional Park of the High Modena Appenines.Specimens were preserved in 5% formalin.In the laboratory, animals were processed through a series of sieves (5, 2, 1 and 0.5 mm mesh size), preserved in 70% ethanol and then sorted.Hydrachnidia were preserved in Koenike's fluid, clarified in Andre's fluid and mounted in Hoyer's medium for identification.The identification took place under a stereomicroscope or a microscope to the lowest possible taxonomic level.The word taxa was used in the results and discussion paragraphs to relate different groups to the lowest taxonomic level.
All the identified material is available for study as alcohol-preserved samples or permanent slide collections in the Department of Life Sciences at the University of Modena and Reggio Emilia.

RESULTS
The values of the measured physico-chemical parameters are shown in Table 1.The strongest variations were found in water temperature.It ranged from 4.5°C in spring 1999 at site 1, to 20.5°C at site 2 in summer 2006.Oxygen had low concentration but presented seasonal variations: its maximum value was reached in spring 1999 with 8 mg•l -1 (site 4) and a saturation of 80% at site 4; its minimum value was reached in summer 2006 when the oxygen concentration was 0.4 mg l -1 at site 5 with a saturation of 6%.The pH values resulted relatively homogeneous, both in space and time.The maximum value of 7.16 was recorded at site 4 in spring 1999 and minimum of 5.18 recorded at site 1 in summer 1999.Conductivity ranged from 107.70 μS cm -1 and 36.00 μS cm -1 evidencing a gradual decreasing of the values from spring to autumn in all the sampling sites.A total of 82 different taxa divided in four phyla, belonging to seven classes, 18 orders and 39 families (Table 2) were recorded during the samplings.The richest group was Diptera with 31 taxa, followed by Coleoptera with nine taxa, Oligochaeta and Arachnida with eight taxa.Odonata and Trichoptera were represented by five taxa, Hirudinea by four, Gastropoda by two and Malacostraca, Ephemeroptera, Plecoptera and Leptolida were each represented by one taxon.
During the spring of 1999, 31 taxa were recorded, 40 taxa were recorded during the summer of 1999, while 22 taxa during autumn 1999.In summer 2006, a total of 59 taxa were found.Summer resulted the most reach season in terms of biodiversity collected.

DISCUSSION
This contribution to the invertebrate macrofauna of a pond in the northern high Apennines is a first attempt to fill a gap in our knowledge.The high number of taxa identified (82) confirms the importance of the Lago Pratignano for macroinvertebrate biodiveristy in the province of Modena and in the northern Apennines.
Comparing the results with other European systems, the Lago Pratignano was found to be extremely rich in the number of taxa (Boix et al. 2001;Sahuquillo et al. 2007;Oertli et al. 2008;Céréghino et al. 2012;Guareschi et al. 2012;Novikmec et al. 2015); at the same time, comparisons of the results with high-altitude habitats in the Alps (Boggero et al. 2005;Boggero and Lencioni 2006;Steingruber et al. 2013) and in the central part of the Apennines, where Solimini et al. (2008) found 61 taxa in a total of 31 ponds, highlight the richness of Lago Pratignano.These results confirm that the northern Apennines could represent an important area for further in-depth investigations of the macroinvertebrate communities of ponds.Moreover, comparison of Coleoptera from Lago Pratignano to a publication by Mazzoldi et al. (2009) found diversity (30 species) to be greater in this study; two species of Dytiscidae are extremely interesting for their rarity and some individuals belonging to the genus Helophorus are now under further study because they could represent a new endemic taxon (Mazzoldi et al. 2009).The possible presence of Dicrotendipes lobiger in this study should be further investigated because it is a species that is typical of central and northern Europe and alpine region.There is only one station in the central Apennines, and so, it could be considered as a glacial relict (Nocentini 1985).
Unfortunately, no data are available for other ponds of the same region and no comparisons can be made, but from this first list of species it resulted clear that more effort should be made in studying these systems.The climate of the region, the geographic localization and the low human impact on the area could contribute to the richness and peculiarity of the Lago Pratignano, but without additional data only a hypothesis can be done.
Annual differences in meteorological conditions and a globally changing climate can affect the flora and fauna, and in particular, animals with short life cycles as are typical of most macroinvertebrates.The higher number of taxa in summer compared to spring and autumn is easily ascribable to the region's climate.Differences between 1999 and 2006 are also attributable to the periodicity of some groups: the plecopteran Nemoura cinerea and the odonate Libellula quadrimaculata, for example, are typically found in spring and rarely in summer.Finally, the low diversity of gastropods could be correlated with the physico-chemical properties of the water and in particular with the relatively low pH.In fact, the values recorded during the samplings vary from 5.18 to 7.16 (Table 1) which are values typically obtained from peat bog habitats (Minelli 2004).Low pH values such as these are not ideal for these organisms.
In conclusion, the contribution of the macroinvertebrate community of high altitude aquatic habitats in the northern Apennines to the biodiversity is here highlighted.The Lago Pratignano resulted to be important not only for its particularly interesting flora and amphibian fauna but also for its rich macroinvertebrate community.The data presented here will be useful in the future to understand the natural transformations of this habitat and the possible alterations caused by the climate change.Furthermore, this work represents a starting point for the study on much-neglected pond habitats in the northern Apennines.

Figures 2 and 3 .
Figures 2 and 3.The pond Lago Pratignano.2: Map of the Lago Pratignano showing the location of the sampling stations.3: View of the pond from sampling station 5.
Ansaloni et al. | Macroinvertebrates of the Lago Pratignano

Table 1 .
Physico-chemical parameters of the pond Lago Pratignano recorded during the samplings.

Table 2 .
Checklist of benthic macroinvertebrates of the pond Lago Pratignano.Plus sign indicate presence of taxa at sampling stations.