The introduction of Physa acuta (Gastropoda: Physidae) on Ilha Grande, Southeast Brazil, from initial stages to an established population

This study presents a four-year follow-up of an introduced population of Physa acuta Draparnaud, 1805, from initial stages to an established population. This introduction occurred on a small impacted stream of Vila do Abraão, the main village of Ilha Grande (Angra dos Reis, Rio de Janeiro, Brazil). The population size increased during the study, and presented a relationship to environmental factors, especially with rainfall. On the initial stages of introduction prevailed the smaller specimens, but on the overall, predominated the intermediate size classes. After less than a year, P. acuta becomes established on this stream and was possibly affecting the other species found on the stream. The information presented here is useful to understand the invasion process of invasive snails, as well as directing conservation efforts.

Molecular Phylogenetics of Physa acuta (Pulmonata: Basommatophora): an Invasive species in Central Punjab Pakistan

Physids belong to Class Gastropoda; belong to Phylum Mollusca and being bioindicators, intermediate hosts of parasites and pests hold a key position in the ecosystem. There are three species of Genus Physa i.e. P. fontinalis, Physa acuta and P. gyrina water bodies of Central Punjab and were characterized on the basis of molecular markers High level of genetic diversity was revealed by polymorphic RAPD, however SSR markers were not amplified. The multivariate analysis revealed polymorphism ranging from 9.09 percent to 50 percent among the three Physid species. Total number of 79 loci were observed for the three species under study and 24 loci were observed to be polymorphic. These RAPD fragment(s) can be developed into co dominant markers (SCAR) by cloning and can be further sequenced for the development of the Physa species specific markers to identify the introduced and native species in Pakistan.

Vodní měkkýši přírodní rezervace Krabonošská niva [Aquatic molluscs of the Krabonošská niva Nature Reserve]

A floodplain of the Lužnice river at the Czech-Austrian border is protected by the Krabonošská niva Nature Reserve (Southern Bohemia, Czech Republic). This floodplain has a relatively natural character and, in addition to the Lužnice river, there is a high diversity of habitats at various stages of succession such as oxbows, pools and temporary wetlands. Altogether 20 species were found at 15 sites studied in 2021. Common and widespread gastropods Lymnaea stagnalis, Segmentina nitida and Planorbarius corneus belonged among the most often recorded species. Endangered Pisidium globulare was found at two sites, and only one non-native species Physa acuta was recorded. Molluscan assemblages are very similar to the assemblages of the neighboring Horní Lužnice Nature Reserve.

The Orava dam reservoir – an important site of aquatic molluscs in north-western Slovakia

Mollusc assemblages of the Orava reservoir, the biggest dam reservoir in Slovakia, were studied in 2020. The reservoir, built in 1941–1953, is situated in north-western Slovakia. Sixteen aquatic mollusc species (13 gastropods, 3 bivalves) were recorded. Valvata piscinalis (O. F. Müller), Radix auricularia (Linnaeus) and Gyraulus parvus (Say) were the most frequent; they were recorded in more than ten sites each. Rich mollusc assemblages, composed mainly of gastropods, were found in sites with rich littoral vegetation of macrophytes. The bivalve diversity and abundance were very small, especially compared to the other studied dam reservoirs. The current results were compared with the previous surveys. The occurrence of Radix lagotis (Schrank) is its first reliable record in Slovakia. Viviparus acerosus (Bourguignat), Aplexa hypnorum (Linnaeus), Anodonta cygnea (Linnaeus), non-native Potamopyrgus antipodarum (Gray) and Physa acuta (Draparnaud) were recorded in this area for the first time and their sites are outside their known range in Slovakia.

No effects of waterproof marking on the behaviour and growth of Physa acuta Draparnaud, 1805 (Gastropoda: Hygrophila: Physidae) in the laboratory

Physa acuta Draparnaud, 1805 is one of the most common freshwater gastropod species, with worldwide distribution. It is an effective periphyton grazer and a potential keystone species in shallow-water systems, where it can boost macrophyte well-being and thus help maintain high water clarity even in nutrient-rich habitats. P. acuta also has been extensively studied in ecotoxicological and behavioural investigations. Such investigations may require observations on individual snails. A method to distinguish individual snails in small-scale experiments is marking their shells with paint dots. However, such marking must not influence snail behaviour (nutritional, reproductive, respiratory, etc.) or growth to avoid confounding effects. Earlier investigations point to no or very limited effects of marking on aquatic and terrestrial snail survival, behaviour, and growth. We tested whether marking could affect the behaviour (as snail activity) and growth of P. acuta using a waterproof, oil-based, non-toxic, fine-point car-body paint marker. Snails were divided into a “marked” and an “unmarked” (control) group of ten snails each in an eight-day experiment. The marking had no effect on the snail activity or growth. The snails survived the experiment and produced egg clutches well beyond the eight-day period. The marking persisted without fading during and beyond the experimental period. Our results support earlier findings that the use of oil-based, non-toxic markers can assist in carrying out reliable observations on individual snails, including the small-bodied P. acuta. Combinations of two dots of different colours allow simultaneous observations on a high number of replicate individuals.

Occurrence of BIOMPHALARIA GLABRATA and PHYSA ACUTA (gastropoda: mollusca) snails in Quinta da Boa Vista municipal park, Rio de Janeiro, RJ, Brazil

The human species has an emotional connection with nature called “biophilia” (or, love for life). This connection goes from generation to generation, being one of the reasons why green spaces are present in large cities. Quinta da Boa Vista is a municipal park in Rio de Janeiro located in the São Cristóvão neighborhood in the northern part of the city. Its main attraction is the artificial lake system, a leisure attraction for the local community. This article reports the presence of Biomphalaria glabrata and Physa acuta snails around the main lake in the Quinta da Boa Vista Municipal Park in Rio de Janeiro, RJ. Seventy-one B. glabrata and twenty-seven P. acuta snails were collected. The snails were measured and examined for the presence of trematode larvae according to standardized procedures. The prevalence rate of B. glabrata was estimated at 15.5%. Rediae and cercariae resembling those of the species Typhlocoelum cucumerinum (Typhlocoelidae, Digenea) which parasitizes aquatic birds of the order Anseriformes were found. This study reinforces the importance of monitoring park lakes and ponds to better understand the risk of helminth transmission by molluscan vectors.KEY WORDS: Snails; Schistosomiasis; Digenea; Quinta da Boa Vista; Rio de Janeiro.