The use of Chara spp. (Charales: Characeae) as a bioindicator of physico‐chemical habitat suitability for an endangered crayfish Austropotamobius pallipes in lentic waters

Abstract

Austropotamobius pallipes is an endangered decapod attracting much attention in freshwater conservation programmes. In some cases population transfers or reintroductions are carried out in lentic ecosystems such as ponds or quarries. Such conservation actions require rapid, low cost and powerful tools to census suitable habitat. Some species of the Characeae family (Chara spp.), share ecological needs with A. pallipes and are proposed as bioindicators of suitable habitat. Chara species were tested, among other plants, as bioindicators, and to see whether Chara species are a stronger indicator than water chemistry. The Pinail Nature Reserve, with 3000 permanent ponds, is inhabited by white‐clawed crayfish probably introduced historically into ponds used for fish production. This allows a replicated study of suitable habitats where plant communities are bioindicators of crayfish presence. Crayfish presence is associated with Chara species (such as Chara aspera, Chara virgata, Chara fragifera, Chara polyacantha and Chara vulgaris). Austropotamobius pallipes is present in ponds with Chara spp. (N = 10/10) while other ponds without crayfish are lacking charophytes (N = 1/23). Algae of the genus Chara are thus a simple and low‐cost additional tool for determining suitable habitat for crayfish introductions within enclosed waters protected from exotic invasive species and disease. Cladium mariscus also appears to be another useful bioindicator for crayfish habitat.

Native top-predator cannot eradicate an invasive fish from small pond ecosystems

“…In 2013, a total of 39 ponds known to contain pumpkinseed in 2013 and 2005 were randomly selected. These ponds as all ponds of the Pinail are relatively small (Figure 1), with an 6 average area of 92.3 ± 20.3 m² and water depth ranging from 1 to 2.6 m with an average of 1.6 m. The physicochemical parameters of these ponds were similar to the majority of the acidic ponds of the Pinail (pH<6.8) with similar vegetation covers (Beaune et al, 2018a, Beaune et al, 2018b. In addition, the diversity in alternative prey for pike is very limited: with L. gibbosus presence, there is no crayfish, few amphibians (Préau et al, 2017) and in the ponds of the study no other fish were captured (Castelnau et al, 2016).…”

“…The study area is covered with diversified Erica moors on acid and oligotrophic ground (podzol) resulting from human pasturing and burning (Pernat et al, 2017). For centuries, humans have used the ponds as temporary reservoirs for fish and several native and non-native species have been introduced in these initially fishless ecosystems (Beaune et al, 2018a), including Ameiurus melas (Rafinesque, 1820); Anguilla anguilla (Linnaeus, 1758); Carassius auratus (Linnaeus, 1758); Carassius carassius (Linnaeus, 1758); Cyprinus carpio Linnaeus, 1758; Esox lucius Linnaeus, 1758; Lepomis gibbosus (Linnaeus, 1758); Leucaspius delineatus (Heckel, 1843); Rutilus rutilus (Linnaeus, 1758); Scardinius erythrophthalmus (Linnaeus, 1758); Tinca tinca (Linnaeus, 1758). Unfortunately, no information is available on the history of introduction of fish, including pumpkinseed, in these ecosystems.…”

Distribution of Aquatic Macrophytes in the Littoral of Lake Bohinj (Slovenia)

“…The water transparency was not an important factor influencing the distribution of macrophytes. Some Chara species are an indicator of good ecological quality [36], such as C. aspera, one of the two Chara species found in the conducted survey.…”

Stream restorations with meanders increase dragonfly and damselfly diversity and abundance, including an endangered species

“…The reserve is covered with diversified Erica moors on acid and oligotrophic ground (podzol). This site forms a very rich ecocomplex where 2 500 species (fauna, flora, fungi) are listed (Beaune et al, 2017;Beaune et al, 2018;Beaune et al, 2019).…”