# Diversity and Seasonal Dynamics of Airborne Fungi in Nerja Cave, Spain
## 4 Discussion
On the contrary, _A. versicolor_ is not detected outside the cave in summer, but its concentration is high inside the cave. The highest frequency of _A. versicolor_ in summer, unlike other species of the genus _Aspergillus_, points to a relationship with the increasing of nutrient sources, i.e., phototrophic biofilms or bat droppings, and could be explained by the ventilation mode of Nerja Cave during this period of the year (DAF-mode). The colder and denser Nerja Cave air is removed through the lower entrances (E1, E2 and E3 in Figure 1) and external air is sucked in through the Pintada Cave and other nonaccessible entrances located in the Almijara range. This suction effect causes the air previously stored in the PC and the GC to reach Nerja Cave. Thus, the source of these fungi would not be the external atmosphere but the cave air previously stored in PC, GC, and other possible subterranean voids connected to Nerja Cave and located in higher altitude. This also applies to _A. spaleaus_, found in 2011 with some frequency in the sediments of Nerja Cave. The study of the isolated strains established the bases for the description of these strains as a new species [57]. A subsequent visit in 2012 allowed the isolation of new strains [57; 32]. As far as we know, no other records on this _Aspergillus_ were published. Another new species of _Aspergillus_ isolated in Nerja was _A. baeticus_. This was described in 2012 [58], and the type strain was isolated from sediments from Gruta de las Maravillas (Aracena, Huelva) along with other strains from Tesoro Cave. In addition, this fungus was isolated from air, cave sediments, and a dead spider (_Agracina cristiani_) in Movile Cave, as well as from a bat cadaver in Demanovska Peace Cave [59], and from cave sediments in Nerja Cave [32]. The new species _Aspergillus europaeus_ was isolated in 2011 from soils near Nerja and Movie caves, although no isolates were obtained directly from the caves [57]. We isolated this fungus in the air of the Entrance Hall in winter, suggesting an origin from the soil outside the cave and their transport inside, according to the UAF-mode ventilation [28]. Less abundant _Aspergillus_ species identified in the air of Nerja Cave were also recorded in different caves such as _A. ochracus_[55; 60; 61; 62]. No cave record was found for _A. pulvericola_ and _A. welwitschiae_. The genus _Penicillium_ is widely distributed in caves, and in Nerja, it was recorded in the two seasonal samplings in almost all the halls; although generally with little abundance in summer, not so in winter. In summer, six species of _Penicillium_ were recorded in all the halls except in the Lance, while in winter, a total of 10 species were recovered in all the halls but not in the Lance. This is the same trend recorded for _Aspergillus_; very abundant in winter, and scarce in summer. The most abundant _Penicillium_ species was _P. flavigenum_, both in summer and winter, although with marked differences in their total abundances and presence in the halls (Tables 2 and 3), and _P. glabrum_, which was only identified in winter. _P. flavigenum_ and _P. glabrum_ are relatively common in caves [55; 56; 57; 58; 49; 50; 55; 63; 64; 65; 66]. [PERSON] et al. [67] found that _P. glabrum_ was among the three most frequent species of fungi present inside Danish houses. The presence of spores of _Penicillium_, in autumn and winter, in the air of Tesoro Cave, was important [30], as it suggests that this genus is abundant in the air of the caves of Malaga province in periods when ventilation is greater. Relatively less abundant species compared with _P. flavigenum_ and _P. glabrum_ were _P. sumatrense_, _P. steckii_, _P. pancosmithum_, _P. citrosulfuratum_, _P. nodositatum_ in summer, and _P. brevicompactum_, _P. rubens P. pancosmithum_, _P. olsonii_, _P. sumatrense_, _P. raistrickii_, and _P. fellutanum_, in winter. Moreover, similar to _Aspergillus_, _Penicillium_ showed higher diversity in winter. _Talazromyces brunneus_ was isolated in winter from Ghosts and Cataclysm halls.