**6. Macroscopic terrestrial algae**

*Glaciers and the Polar Environment*

annihilated. Who does that? If not an animal, mostly a set of lichens. If we look at the work already done with phytosociology in Antarctica, we see that lichens have figured as one of the most important when considering the ecological significance index [17]. **Figure 15** illustrates how different species are associated with a lichen which in this case is fruticose: *Sphaerophorus globosus*, which forms groups up to 10 cm in height and is generally parasitic on mosses (muscicolous). In this 20 x 30 square in the figure, there are associated eight other species, of which 3 are mosses and 5 are other lichens, demonstrating how the lichen community settles on mosses and needs them to develop, even if it results in its death. In succession, it is to be expected, therefore, that lichens from the vegetation damage or kill a previously installed moss and then gradually disappear, also due to the lack of a host.

In this community the mosses are at a disadvantage, as they are being attacked by various parasites of the lichen group. These parasites do not even care about the moss species, but it looks like the *Chorisodontium acyphyllum* moss is surviving well and unscathed. This is also noticed in other parts and perhaps indicates that this moss ends up taking the place of the other parasitized and previously killed. This may show a stage of plant succession in Antarctica, which is still poorly studied. Lichens can also occur on rock fragments and in **Figure 16** there is a schematic drawing of the cover of round rocks, very common in uplifted areas. There are

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**Figure 16.**

**Figure 15.**

*Biodiversity surrounding the fruticose lichen* Spaerophorus globosus.

*Biodiversity in a 20 x 20 cm square of rounded rocks in Henequin point, King George Island, with 18 species.*

*Prasiola* is the macroscopic alga that occurs in terrestrial environments in the Antarctic region with greater frequency. Only two species were being cited for the area: *P. crispa* (nitrophilous) and *P. calophylla* (nitrophobous) (Putzke & Pereira, 2013). Studying the molecular phylogeny of these algae in Antarctica, the presence of *P. crispa* was confirmed, that *P. calophylla* is different from the same species mentioned for Europe, changing its name to *P. glacialis* and that *Prasiola antarctica* is an independent species, morphologically identical *P. crispa* [57].

These species are among the largest primary producers in Antarctica and studies have shown that *P. crispa* is very resistant to desiccation and hypersaline conditions [58–61].

In general, nitrophilic species occur near or inside bird colonies and nitrophobic in areas in contact with them. Often, some shallow pools of water have groups of *Prasiola* that prevent the growth of the surrounding mosses, demonstrating that they are somewhat allelopathic.

In several places it can be seen that the alga is lichenized, forming a different, more blackened and dotted thallus. It is the association with the fungus *Mastodia tesselata*, whose relationship is still controversial, as some authors believe it is parasitism and not a symbiosis. The lichen appears close to Verrucaria, a lichen with marine affinities [62].

In some cases, during the collections it can be seen that part of the algae stem is green and part is associated with the fungus and is already blackened, showing that the association may not be complete. Further studies are needed to elucidate what is the relationship between these two very different organisms.

*P. crispa* produces secondary metabolites with high toxicity and insecticidal power, and some studies on the subject have already been published [63, 64].
