**3.1 Ground beetles on glaciers**

Clean glaciers and debris-covered glaciers can host permanent populations of ground beetles, at least on the European glaciers since, to our knowledge, there are no data from other extra-European mountain chains. All the species found on the European glaciers belong to the genera *Nebria* and *Oreonebria*. The *Nebria/*

#### **Figure 2.**

*The non-biting midge* Diamesa zernyi *larva (a) from the Amola glacial stream (2540 m a.s.l.) and a couple of adults (male on the left, female on the right) (b) walking on the Presena Glacier (2700 m a.s.l.) (Adamello-Presanella Mts., Italian Alps) (photo by V. Lencioni) (a) and F. Pupin/archive MUSE (b). Animal sizes ca 1 cm.*

**147**

*Glacial Biodiversity: Lessons from Ground-dwelling and Aquatic Insects*

*Oreonebria* species living on clean glaciers are with reduced and not functional wings and wander on the glacier mainly during the night searching for preys (mainly springtails, spiders, non-biting midges and died insects). During the day, they find refuge under the rocks on glacier surface and within the moraines. Their legs are longer with respect to those closely-related species living at lower altitudes and in different habitats, in order to maintain the body to a higher distance from the

In addition, debris-covered glaciers are able to host permanent population of *Nebria/Oreonebria* species (**Figure 3**). Currently, data are available for five debris-

*Nebria/Oreonebria* are olfactory-tactile predators; it means that they use the chemoreceptors located on the antenna as instrument to find preys on the glacier surface or between the stony debris. Therefore, these organisms are well adapted to move between the stony debris covering the glaciers, thus across a three-dimensional space. The sex ratio on the glacier is female-biased [29], and the colonization of the glacier from the neighboring habitat seems be done by females that have a higher

The gradual melting of glaciers leave in front of them large areas of barren, pristine ground open for colonization of various life forms. Among these, ground beetles can be found along the entire glacier foreland. Ground beetles can colonize entire glacier forelands, from sites deglaciated since more than one-hundred years

The colonization of a glacier foreland by ground beetles is triggered mainly by time since glaciation, distance to glacier and vegetation cover, as highlighted by studies carried out in Northern Europe (e.g., [30–32]), Alps (e.g., [27, 33–36]) and more recently Andes [37]. The colonization of a glacier foreland by ground beetles can follow two different models: the "addition and persistence" and "replacement-change" models [31]. The former was mainly observed in Northern-Europe and on Andes [31, 37], with an exception in the peripheral mountain range of the Southern Alps [38]. It consists in the persistence of pioneer species (i.e., the initial colonizers, e.g., *Nebria* spp. in Europe; *Dyscolus* spp. on the Andes [37]) from the sites deglaciated few years ago (early successional stages) to sites deglaciated more than 100 years ago (late successional stages)—in this case, there is no species turnover along the chronosequence of glacier retreat. The "replacement-change" model, mainly observed on the Alps (e.g., [17, 36]), consists in a group of initial colonizers (the pioneer community) progressively replaced over time by one or more other species assemblages; thus, in this case, there is a clear species turnover. Notwithstanding these different models of colonization, Northern Europe and Alps share ground beetles belonging to common genera and exhibiting the same patterns of colonization. For instance, the species belonging to the genus *Nebria* are surface active predators able to immediately colonize deglaciated terrains of the European glacier forelands. The species belonging to the genus *Amara* and *Carabus*, the former omnivorous and the latter specialized predators, arrived on a deglaciated terrain after more than 20 years [30, 33]. A quite common pattern observed along the European glacier forelands is that the number of species increases with the time since deglaciation, with a more diversified

The speed of colonization along the glacier forelands varies with the time since deglaciation. Specifically it is high in the first years after the glacier retire due to the low competition in colonizing pristine terrains, while it is low in terrains located

*DOI: http://dx.doi.org/10.5772/intechopen.92826*

covered glaciers of the Italian Alps [17, 18, 27, 28].

propensity to disperse than males [29].

**3.2 Ground beetles along glacier forelands**

to sites deglaciated since one year (**Figure 4**).

community on terrains deglaciated 100 years ago.

frozen ground [26].

*Glacial Biodiversity: Lessons from Ground-dwelling and Aquatic Insects DOI: http://dx.doi.org/10.5772/intechopen.92826*

*Glaciers and the Polar Environment*

streams, springs and lakes.

**3.1 Ground beetles on glaciers**

flagship organisms of the glacial biodiversity.

belonging to the Italian carabid fauna are endemic.

disappearing) or changes in microhabitat conditions (e.g., permafrost melt). Most of the species living at high altitudes and latitudes have low dispersal abilities due to the lack of wings and are walking colonizers, ground hunters and small-sized, which are traits typical of species living in cold, wet and gravelly habitats [17]. To date, about 40,000 species are known in the world [20] and most of them are endemic to specific areas [21–23]; for instance, about 28% of the total species

Non-biting midges (**Figure 2**) are the freshwater insect family that comprises the highest number of species, both in lentic and lotic habitats [24]. They are the most widespread of all aquatic insect families, with individual species occurring from Antarctica to the equator lands and the Arctic, from lowlands to thousands of meters of altitudes. There are species that thrive in almost every conceivable freshwater environment. Ice-cold glacial trickles, hot springs, thin films, minute containers of water in the leaf axils of plants and the depths of great lakes all have their characteristic species or communities. There are semiaquatic species, living in moist soil or vegetation and others that are truly terrestrial with few species occurring in marine water. Some species tolerate brackish water, others thrive in intertidal pools and, unusually among the insects, and a few are truly marine. Survival in harsh environments is due to a series of adaptations. Among these are the production of melanin, their small size, capacity for mating on the ground instead of in flight (they therefore have small or totally absent wings), the building of cocoons, diapause and resistance to cold [25]. To date, about 6500 species are known in the world; one tenth of which are in Italy and one thousandth in Alpine

Thanks to their species richness, adaptation to cold environments, key role in the ecological network structure and robustness and sensitivity to short-term and longterm climate changes, ground beetles and non-biting midges might be considered

Clean glaciers and debris-covered glaciers can host permanent populations of ground beetles, at least on the European glaciers since, to our knowledge, there are no data from other extra-European mountain chains. All the species found on the European glaciers belong to the genera *Nebria* and *Oreonebria*. The *Nebria/*

*The non-biting midge* Diamesa zernyi *larva (a) from the Amola glacial stream (2540 m a.s.l.) and a couple of adults (male on the left, female on the right) (b) walking on the Presena Glacier (2700 m a.s.l.) (Adamello-Presanella Mts., Italian Alps) (photo by V. Lencioni) (a) and F. Pupin/archive MUSE (b).* 

**146**

**Figure 2.**

*Animal sizes ca 1 cm.*

*Oreonebria* species living on clean glaciers are with reduced and not functional wings and wander on the glacier mainly during the night searching for preys (mainly springtails, spiders, non-biting midges and died insects). During the day, they find refuge under the rocks on glacier surface and within the moraines. Their legs are longer with respect to those closely-related species living at lower altitudes and in different habitats, in order to maintain the body to a higher distance from the frozen ground [26].

In addition, debris-covered glaciers are able to host permanent population of *Nebria/Oreonebria* species (**Figure 3**). Currently, data are available for five debriscovered glaciers of the Italian Alps [17, 18, 27, 28].

*Nebria/Oreonebria* are olfactory-tactile predators; it means that they use the chemoreceptors located on the antenna as instrument to find preys on the glacier surface or between the stony debris. Therefore, these organisms are well adapted to move between the stony debris covering the glaciers, thus across a three-dimensional space. The sex ratio on the glacier is female-biased [29], and the colonization of the glacier from the neighboring habitat seems be done by females that have a higher propensity to disperse than males [29].

## **3.2 Ground beetles along glacier forelands**

The gradual melting of glaciers leave in front of them large areas of barren, pristine ground open for colonization of various life forms. Among these, ground beetles can be found along the entire glacier foreland. Ground beetles can colonize entire glacier forelands, from sites deglaciated since more than one-hundred years to sites deglaciated since one year (**Figure 4**).

The colonization of a glacier foreland by ground beetles is triggered mainly by time since glaciation, distance to glacier and vegetation cover, as highlighted by studies carried out in Northern Europe (e.g., [30–32]), Alps (e.g., [27, 33–36]) and more recently Andes [37]. The colonization of a glacier foreland by ground beetles can follow two different models: the "addition and persistence" and "replacement-change" models [31]. The former was mainly observed in Northern-Europe and on Andes [31, 37], with an exception in the peripheral mountain range of the Southern Alps [38]. It consists in the persistence of pioneer species (i.e., the initial colonizers, e.g., *Nebria* spp. in Europe; *Dyscolus* spp. on the Andes [37]) from the sites deglaciated few years ago (early successional stages) to sites deglaciated more than 100 years ago (late successional stages)—in this case, there is no species turnover along the chronosequence of glacier retreat. The "replacement-change" model, mainly observed on the Alps (e.g., [17, 36]), consists in a group of initial colonizers (the pioneer community) progressively replaced over time by one or more other species assemblages; thus, in this case, there is a clear species turnover. Notwithstanding these different models of colonization, Northern Europe and Alps share ground beetles belonging to common genera and exhibiting the same patterns of colonization. For instance, the species belonging to the genus *Nebria* are surface active predators able to immediately colonize deglaciated terrains of the European glacier forelands. The species belonging to the genus *Amara* and *Carabus*, the former omnivorous and the latter specialized predators, arrived on a deglaciated terrain after more than 20 years [30, 33]. A quite common pattern observed along the European glacier forelands is that the number of species increases with the time since deglaciation, with a more diversified community on terrains deglaciated 100 years ago.

The speed of colonization along the glacier forelands varies with the time since deglaciation. Specifically it is high in the first years after the glacier retire due to the low competition in colonizing pristine terrains, while it is low in terrains located

far from the glacier front because more competitive in terms of microhabitat and resource availability [35]. In the contest of the ongoing climate warming, it is interesting to highlight that an increase of 0.6°C in summer temperatures approximately doubled the speed of initial colonization, whereas later successional stages were less sensitive to climate change [39].

#### **Figure 3.**

*Stony debris covering the surface of the Sorapiss Centrale glacier (45°N, 12°E, Ampezzo Dolomites, Italian Alps); it hosts permanent populations of cold-adapted ground beetles, spiders and springtails (photo by M. Gobbi).*

**149**

**Figure 4.**

*period (photo by M. Gobbi).*

**3.3 Ground beetles on rock glaciers**

Currently, data on ground beetles found on rock glaciers are available only for the Italian Alps [16, 40 41]. Active rock glaciers are a unique landform: the occurrence of permafrost and the size of the stones differentiate them from the

*Pitfall trap near the front of the Agola Glacier (46°N, 10°E, Brenta Dolomites, Italy). Pitfall trapping is one of the most successful methods to collect ground-dwelling invertebrates at high altitudes during the snow free* 

*Glacial Biodiversity: Lessons from Ground-dwelling and Aquatic Insects*

*DOI: http://dx.doi.org/10.5772/intechopen.92826*

*Glacial Biodiversity: Lessons from Ground-dwelling and Aquatic Insects DOI: http://dx.doi.org/10.5772/intechopen.92826*

#### **Figure 4.**

*Glaciers and the Polar Environment*

sensitive to climate change [39].

far from the glacier front because more competitive in terms of microhabitat and resource availability [35]. In the contest of the ongoing climate warming, it is interesting to highlight that an increase of 0.6°C in summer temperatures approximately doubled the speed of initial colonization, whereas later successional stages were less

*Stony debris covering the surface of the Sorapiss Centrale glacier (45°N, 12°E, Ampezzo Dolomites, Italian Alps); it hosts permanent populations of cold-adapted ground beetles, spiders and springtails (photo by* 

**148**

**Figure 3.**

*M. Gobbi).*

*Pitfall trap near the front of the Agola Glacier (46°N, 10°E, Brenta Dolomites, Italy). Pitfall trapping is one of the most successful methods to collect ground-dwelling invertebrates at high altitudes during the snow free period (photo by M. Gobbi).*

#### **3.3 Ground beetles on rock glaciers**

Currently, data on ground beetles found on rock glaciers are available only for the Italian Alps [16, 40 41]. Active rock glaciers are a unique landform: the occurrence of permafrost and the size of the stones differentiate them from the surrounding landforms (e.g., scree slopes) in terms of temperature regime and depth of the substrate. Active rock glaciers show occurrences of cold-adapted species. Even though ground beetle communities of active rock glaciers show few differences in terms of species richness and abundance with respect to scree slopes, some characteristic species of each of the two landforms can be identified. The ground beetle community observed on the rock glaciers is exclusive of this landform because it is composed of large populations of species belonging to the genera *Oreonebria*, *Nebria* and *Trechus* [16, 40]. To these genera belong species (e.g., *Nebria germari*, *Oreonebria soror* and *Trechus tristiculus*) typical of cold and wet highaltitude environments. These species have two kinds of life style: epigeic (they move on the surface of the rock glacier where the rocky detritus is fine) and endogeic (they reach the depth of the stony detritus moving between the interstitial space between stones). Conversely, the surrounding ice-free landforms (e.g., scree slopes) host species assemblages characterized by the presence of species typical of alpine grasslands (e.g., *Carabus* spp. and *Cymindis vaporariorum*). Therefore, an active rock glacier can be defined as a superficial subterranean habitat [16] represented by fissure network among boulders, human-sized caves included.

Unlike other superficial subterranean habitats like scree slopes, where temperatures could reach relatively high values in summer [16, 42], rock glaciers are selected by cold-adapted species, which avoid scree slopes as they do not offer constantly low temperatures during summer.
