Odonata - Entomological Society of Latvia - Latvijas Daba

suitability of a habitat is characterized more by the vegetation, rather than its origin (natural vs.
man-made).
L. caudalis in Latvia is mostly found in eutrophic lakes (51 %), less frequently in oxbows
(18 %) and dystrophic lakes (16 %). This is accounted by the fact that the species generally prefers
habitats with rich under-water (Potamogetonetea – type vegetation) vegetation and, unlike other
Leucorrhinia species, can survive in water bodies with high density of fish (Mauersberger, Heinrich
1993; Dijkstra 2006). Nevertheless, Bernard et al. (2002) notes that the species inhabits water
bodies with low trophia and with the growing of trophia, the species may diminish and fully
disappear from the specific water body. Rather frequently the species has been found in oxbows,
although this is more characteristic to the periphery of the distribution area and is less popular
habitat (Dijkstra 2006; Bernard et al. 2009). Several localities have been found in old peat quarries
with well developed above-water (Phragmitetea – type vegetation) and under-water
(Potamogetonetea – type vegetation) vegetation.
L. pectoralis, in comparison with the other two species, inhabits broader spectrum of habitats,
as it can be equally often found in eutrophic (26 %) and dystrophic (25 %) lakes and oxbows
(32 %). This corresponds to the description of the species habitats in Europe (Dijkstra 2006). Other
authors (Bernard et al 2002; Mauersberger 2010) as well note that L. pectoralis can be found in
various habitats with very dynamic water regime, temperature and oxygen content. Although
several authors (Wildermuth 1994; Schiel, Buchwald 1998) have mentioned that in the southern
part of the species distribution area this species inhabits water bodies without fish, the latest studies
show that the species in whole area inhabits water bodies with fish (Mauresberger 2010; Petrin et al.
2010). Similarly, in all lakes in Latvia where the species localities have been found, also the
presence of fish has been observed (Birzaks 2007; Ezeri.lv 2011). In all localities of L. pectoralis in
gravel quarries and old peat quarries well-developed and varied above-water (Phragmitetea - type
vegetation) and under-water (Potamogetonetea – type vegetation) vegetation has been found. This
shows that the suitability of a habitat is characterized more by the vegetation, rather than its origin
(natural vs. man-made).
The initial assumption that all three species are closely connected to the oxbows of the Gauja
River was only partially confirmed. In the oxbows of the Gauja River mainly L. pectoralis was
found, less frequently – L. caudalis. In all oxbows where L. caudalis was found, also L. pectoralis
was observed. As L. caudalis is usually observed in a lesser extent than L. pectoralis, it is possible
that the species, at least in oxbows, is more common that previously found.
The amount of data obtained in Tītmaņi oxbow in 2005 allows drawing conclusions only
regarding the L. pectoralis and micro habitats. The species can be found in open habitats with
mainly above-water (Phragmitetea – type vegetation) vegetation. In Tītmaņi oxbow large number
of individuals was found also in the sample area with under-water (Potamogetonetea – type
vegetation) vegetation – a growth of water soldier Stratiotes aloides. This may be due to the fact
that water soldier in the bank of Tītamaņi oxbow creates a think, floating above water vegetation
transiting into a marsh. The high number of individuals in the sample area with the growth of bent
grass Agrostis tenuis shows that the species may also use grass habitats near the water bodies, as
long as they are not enclosed by bushes and trees. The sample areas where the species were not
found were enclosed by bushes and trees (Figure 1).
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