Infestation Rate of Branchiobdellids in Austropotamobius Pallipes Italicus From a Stream of Central Italy: Preliminary Results

ABSTRACT1. As part of the Austropotamobius pallipes species complex, the crayfish Austropotamobius italicus is a species of community interest whose preservation requires the designation of Special Areas of Conservation (SACs) (Annex II, EU Habitats Directive). This study aimed at (1) assessing the conservation status of this threatened indigenous species by stock assessment in Central Italy and (2) identifying some aspects of its elective habitat.2. Surveys were conducted in nine streams harbouring A. italicus (streams WI) and in 10 streams where crayfish populations became extinct at least 5 years before the study (streams WO).3. The results confirmed that A. italicus is a K-selected species, with a relatively slow growth rate (males: 0.34; females: 0.37) and a long life expectancy (males: 8.2 years, females: 7.8 years). The extant populations are healthy, showing balanced sex-ratios and well structured age-class compositions. Mortality is mainly due to fishing, which is illegal in Tuscany.4. Principal Components Analyses showed that the streams WI and WO differ in the abundance of allochthonous plant detritus but not in the taxonomic composition of their macroinvertebrate communities. Age classes were found to be spatially segregated, juveniles mainly using cobbles as substrates and adults seemingly avoiding them.5. The loss of the pristine riverine landscape seems to have been responsible, together with illegal fishing, for the local extinction of the species. As a consequence, retaining, enhancing, and restoring the habitat and its complexity are required for the preservation of A. italicus.6. The designation of SACs might help in this endeavour if accompanied by programmes aimed at publicizing the need for conservation of this species. Unfortunately, crayfish-focused projects supported by LIFE in Italy since 1992 (4%) and the SACs involved (1.4%) have been relatively few, despite the poor conservation status of this species and its well recognized ecological role.

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“…(Branchiobdella sp. is apparently harmless to this species; Gherardi et al, 2002a) and none is affected by Thelolaia sp. or Aphanomyces astaci.…”

Section: Discussionmentioning

confidence: 95%

Conserving indigenous crayfish: stock assessment and habitat requirements in the threatened Austropotamobius italicus

Brusconi¹,

Bertocchi²,

Renai³

et al. 2008

Aquatic Conservation

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“…However, the effect of disinfection is much more evident on these invertebrates. The presence of branchiobdellids has already been observed in crayfish in North Italy (Gherardi et al 2002).…”

Section: Discussionmentioning

confidence: 78%

The use of formaldehyde for the disinfection of maternally incubated eggs of noble crayfish (Astacus astacus)

Sicuro

2016

Int Aquat Res

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The high mortality of maternally incubated eggs represents a serious problem that prevents the development of noble crayfish (Astacus astacus) farming in Italy. In this experiment, formaldehyde bath technique has been tested with maternally incubating females. The survival rate of maternally incubated eggs, exposed to progressively reduced concentrations of formaldehyde (4000, 3000, 2000, 1000, 1500 and 500 mg l -1 ), has been compared with that of untreated controls for two consecutive years (2010 and 2011). The formaldehyde treatments were administered as disinfection baths, for a period of 15 min, twice a week. A concentration of formaldehyde of 500 mg 1 -1 , or greater, was found to be effective in controlling egg mortality, without apparent harming the female broods.

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“…All the crayfish were from two different streams near Rome (Italy): 34 (17 females + 17 males) from River Licenza, where crayfish carried branchiobdellids (WI); 38 (19 + 19) from River Duranna (42°03'06.0" N and 12°55'44.9" E, Rome, Italy) where branchiobdellids were absent (WO). We verified the worm absence by immerging crayfish in a saline solution for few seconds according to Gherardi et al (2002). The River Duranna's environmental features are similar to those of River Licenza.…”

Section: Methodsmentioning

confidence: 99%

“…Holt 1965Holt , 1986Gelder et al 1994;Valvassori et al 1994;Gelder & Ferraguti 2001). On the contrary, poor attention was paid to their ecology and host relationships (Keller 1992;Mori et al 2001;Gherardi et al 2002), and unfortunately in some non-detailed cases (Meike 1999) the Branchiobdella species were not identified.…”

Section: ) Five Belonging To the Genus Branchiobdellamentioning

confidence: 99%

Biological and morphological aspects ofBranchiobdella italica(Annelida: Clitellata) in a native crayfish population of central Italy

Scalici

Giulio

Gibertini

2010

Italian Journal of Zoology

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The present study aimed to improve the knowledge of the biology of Branchiobdella italica, a symbiontic worm on the whiteclawed crayfish Austropotamobius pallipes, with particular attention to the feeding strategy, infestation and colonization ability, and morphology. Branchiobdellids occurred most frequently on adult crayfish rather than juveniles, due to the larger size of the former that permit a higher colonization by epizoic organisms, and to the high moult rate of smaller crayfish. We did not observe massive infestations of branchiobdellids, and the few specimens found do not seem to influence crayfish health. The higher occurrence of branchiobdellids took place on the A. pallipes carapace where worms find trophic resources. Gut content analysis of B. italica showed a generalist feeding strategy. The presence of fungal hyphae found within the gut of B. italica could lead us to infer that branchiobdellids could contribute to limit the fungal growth on the exoskeleton or on eggs of their host. Histological analysis of reproductive traits does not show structural differences from those referred to previous descriptions; the observation of one or two ciliated funnels (not always two), and the absence of hooks or spines on the penis surface, represent the main exceptions. Additional studies are needed to assess the true nature of the symbiosis between branchiobdellids and their hosts.

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Infestation Rate of Branchiobdellids in Austropotamobius Pallipes Italicus From a Stream of Central Italy: Preliminary Results

Cited by 7 publications

References 8 publications

Conserving indigenous crayfish: stock assessment and habitat requirements in the threatened Austropotamobius italicus

Conserving indigenous crayfish: stock assessment and habitat requirements in the threatened Austropotamobius italicus

The use of formaldehyde for the disinfection of maternally incubated eggs of noble crayfish (Astacus astacus)

Biological and morphological aspects ofBranchiobdella italica(Annelida: Clitellata) in a native crayfish population of central Italy

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