Maternal Serotonin: Shaping Developmental Patterns and Behavioral Strategy on Progeny in Molluscs

Serotonin is a well-known neurotransmitter and neurohormone regulating mood, sleep, feeding, and learning in high organisms. Serotonin also affects the embryonic events related to neurogenesis and maturation of hormonal systems, the underlying organism adaptation to a changing environment. Such serotonin-based mother-to-embryo signaling is realized via direct interactions in case of internal fertilization and embryonic development inside the mother body. However, the possibility of such signaling is less obvious in organisms with the ancestral type of embryogenesis and embryo development within the egg, outside the mother body. Our data, based on the investigation of freshwater gastropod molluscs (Lymnaea and Helisoma), demonstrated a correlation between seasonal variations of serotonin content within the female reproductive system, and developmental patterns and the behavioral characteristics of progeny. The direct action of serotonin via posttranslational protein modification—serotonylation—during early development, as well as classical receptor-mediated effects, underlies such serotonin-modulated developmental changes. In the present paper, I will shortly overview our results on freshwater molluscs and parallel the experimental data with the living strategy of these species occupying almost all Holarctic regions.

Annotated and Updated Checklist of Land and Freshwater Molluscs from Asturias (Northern Spain) with Emphasis on Parasite Transmitters and Exotic Species

Land and freshwater molluscs are the most abundant non-arthropod invertebrates from inland habitats worldwide, playing important ecological roles and some being important pests in agriculture. However, despite their ecological, and even economic and sanitary importance, their local diversity in many European regions is not perfectly understood, with a particularly notableknowledge gap in the northern Iberian malacofauna. This work aims at providing a revised checklist of continental gastropods and bivalves from the Asturias (northern Spain), based on the examination of newly collected and deposited material and on the critical analysis of published and gray literature. A total of 165 molluscan species are recognized. Ten species constitute new records from Asturias and seven from northern Iberian Peninsula. Seventeen species are introduced or invasive, evidencing the current increase of the bioinvasion rate in continental molluscs. Furthermore, all these exotic species are parasite transmitters or trematode intermediate hosts, and thus represent a potential bio-sanitary risk for human and other animal health. The provided data strongly suggest that the increase of invasive freshwater snail species can lead to an increase in parasitic infections, and this is a crucial point that transcends the merely scientific to the political-social sphere.

Mollusc Shells from Neolithic Contexts in the Lake Eyasi Basin, Northern Tanzania

The study of the Neolithic period in the Lake Eyasi Basin was dominated by attempts to formulate the area’s chronology, mobility, settlement patterns, subsistence, and cultural capabilities of Neolithic people as attested by domesticated animals, pottery, and lithic artefacts. Occasionally, studies on molluscs were mentioned, but rarely described in detail. Neolithic sites across the Lake Eyasi Basin have yielded remains of both terrestrial (gastropods) and freshwater mollusc shells (mussels). The abundance of mollusc shell remains in the archaeological records of the Lake Eyasi Basin have played a great role in chronological settings, mobility and community integrations, studies of settlement patterns, and other analyses. Mollusc remains have often been widely interpreted as a food supplement to other reliable food resources such as meat, vegetables and fish. Archaeological excavations and detailed analysis of the shells from Mumba rock shelter, Jangwani 3 and Laghangasimjega 2 have shown that molluscs played different roles. They were effectively used in tool manufacturing, as practical implements for handling objects, as scraping tools, as harpoons for fishing weapons, and sometimes for symbolism and in rituals. Terrestrial and freshwater molluscs coexisted in the Lake Eyasi Basin and were utilised equally by the Neolithic people during the Mid-Holocene period. Keywords: Mollusc shells; Neolithic; Lake Eyasi Basin; Northern Tanzania

The freshwater molluscs of Serbia: Annotated checklist with remarks on distribution and protection status

We present a checklist of 86 valid freshwater mollusc species of Serbia (65 gastropods and 21 bivalves) belonging to 19 families (15 gastropods and four bivalves). The list is based on our latest research and includes data from published sources and personal communications. The most diverse family among gastropods is Planorbidae (16 species), while Sphaeriidae are most diverse within the bivalves (10 species). Ten species are local endemics (all of them gastropods), while eight are introduced species (three gastropods and five bivalves). The Danube River and its smaller tributaries harbour the most diverse gastropod community, with a total of 61 species (41 gastropods and 20 bivalves). The snail Theodoxus transversalis (Pfeiffer, 1828) and the bivalve Unio crassus Philipson, 1788 are listed as EN (endangered) on the global (IUCN) level, while the snail Plagigeyeria gladilini Kuščer, 1937 and the bivalves Pseudanodonta complanata (Rossmässler, 1835) and Sphaerium rivicola (Lamarck, 1818) are considered as VU (vulnerable) species. Of those IUCN taxa, only U. crassus is listed as protected on the national level (along with 12 mostly local endemic gastropod species). In comparison with the previous checklist of gastropods by Karaman & Karaman (2007), a total of seven species are added here: Belgrandiella serbica Glöer 2008, Bythinella istoka Glöer & Pešić 2014, B. nonveilleri Glöer 2008, B. pesterica Glöer 2008, Acroloxus lacustris (Linnaeus, 1758), Melanoides tuberculata (O.F. Müller, 1774) and Armiger crista (Linnaeus, 1758). In view of global and regional trends in taxonomy, ecology and invasive biology, an even richer diversity of the Serbian freshwater malocofauna can be expected.

Species diversity and distribution of freshwater molluscs of Javakheti Highlands (Republic of Georgia)

The diversity and distribution of freshwater molluscs is poorly studied in the Republic of Georgia, due to the scarcity of field studies during the last 50 years. Here, we present the results of the first concerted investigation of freshwater mollusc biodiversity in the Javakheti Highlands, in the southern, mountainous region of Georgia. In total, we were able to collect 22 species from 42 sampling localities, including different kinds of freshwater habitats. Amongst the 22 collected species, 12 were recorded for the first time from Javakheti. From the newly-recorded species, Bathyomphalus contortus is a new country record, whose identity is supported by 16S rRNA sequence data.

FORMATION OF BIODIVERSITY OF THE FAUNA OF ECTO- AND ENDOPARASITES ON THE ARARAT PLAIN OF ARMENIA

Our studies were aimed at analyzing biodiversity of ecto- and endoparasites of sheep, cattle, rabbits, domestic birds and dogs in the lowland zone of the Republic, with semidesert climate and height of 850 m above the sea level. This is one of the warm regions of the Republic. The studies performed have established moderate and high degree of animal infection with parasites. We identified 33 parasite species, mostly helminths (15 species), including 10 species of nematodes (Trichocephalus ovis, Nematodirus spathiger, Haemonchus contortus, Chabertia ovina, Dictyocaulus filaria, Muellerius capillaris, Protostrongylus spp., Passalurus ambiqus, Ascaridia galli, Heterakis gallinarum), 4 species of trematodes (Fasciola hepatica, F. gigantica, Dicrocoelium dendriticum, Paramphistomum cervi), 1 species of cestodes (Moniezia expansa), 9 protozoan species (Piroplasma bigeminum, Babesia ovis, Eimeria perforans, E. magna, E. irresidua, E. tenella, E. acervulina), 7 species of ticks, 1 species of insects, and 1 species of leishmaniasis vector, the mosquitos from the genus Phlebotomus. We registered 5 species of freshwater molluscs (Lymnaea auricularia, L. stagnalis, L. ovata, L. truncatula, Planorbis planorbis), and 2 species of terrestrial molluscs (Helicella derbentina, Napaeopsis hohenackeri).

Freshwater molluscs of the Zrmanja and Krupa Rivers (Croatia) – the role of these rivers as a refuge of threatened and endemic species

The Balkan region is inhabited by hundreds of endemic species of freshwater molluscs but the information on their distribution, as well as that on the distribution of more common and widespread species, is still insufficient; most areas have no complete inventories of their mollusc faunas. The Zrmanja is one of the largest rivers in the Adriatic part of Croatia. Its freshwater molluscs were studied in the last decade, resulting in a substantial body of distributional data. The main objective of this study was to summarise and analyse the recent distributional information on its freshwater molluscs, with special reference to endemic or threatened species. In total 33 freshwater mollusc species were found in the Zrmanja River and its tributaries at 73 sites. The middle section of the Zrmanja River and its largest tributary, the Krupa River, were the richest studied parts. Dalmatinella fluviatilis Radoman, Tanousia zrmanjae (Brusina) and Islamia zermanica Radoman, endemic to the Zrmanja catchment area, were found in the middle and lower sections of the river. Their occurrence is scattered and limited in area; T. zrmanjae is probably on the verge of extinction. The occurrence of the endemic Belgrandiella kusceri (Wagner), Hadziella sketi Bole and Kerkia sp. in springs or underground waters and an abundant population of Unio elongatulus C. Pfeiffer in the Zrmanja and Krupa Rivers is also noteworthy. The area can be regarded as an important part of the Balkan region, one of world’s hotspots of global biodiversity. Although it is protected, there are still anthropogenic factors that are negatively affecting or may affect the mollusc assemblages.

Cold tolerance varies among invasive populations of the Asian clam Corbicula fluminea

The distribution of the subtropical Asian clam Corbicula fluminea (Müller, 1774), one of the world’s most invasive freshwater molluscs, is reportedly constrained by a lower thermal tolerance limit of 2°C. Although its occurrence in north temperate regions is typically restricted to artificially heated waterbodies, the species has been found to overwinter in unheated lakes and rivers. In laboratory experiments, we compared the cold tolerance of populations from several geographically distinct sites spanning 35°N to 46°N in eastern North America. Each population contained individuals that fully recovered from two months of continuous exposure to near freezing (1°C) conditions, contrary to published accounts of C. fluminea’s thermal ecology. Survivorship increased with body size and was enhanced by prior acclimation to a low temperature (10°C) compared to a higher one (18°C). When acclimated to 10°C, clams from northern populations exhibited greater survivorship (55.0 ± 16.1%) than those from southern populations (26.7 ± 19.2%). However, one southern population demonstrated survivorship as great as that of the most tolerant northern population, suggesting that its clams could overwinter in unheated northern waterbodies. Differences among populations indicate either that contemporary evolution has occurred or that developmental plasticity shapes future acclimation responses.

Diversity of freshwater molluscs from the upper Brahmaputra Basin, Assam, India

A field survey was conducted for three consecutive years, 2015–17 to assess the diversity of freshwater molluscs (Gastropoda and Bivalvia) of the upper Brahmaputra Basin in Assam, India. Altogether, 18 gastropods and 27 bivalve species representing nine families were recorded from 17 sampling stations comprising small to large tributaries and wetlands in the flood-plains covering a total geographical area of approximately 3,500km2. A large fraction (15.55%) of the collected mollusc species are new records from the upper Brahmaputra Basin of Assam. Rarity in the occurrence of freshwater mollusc was confirmed with singleton and doubleton species accounting for 6.66% and unique species accounting for 35.55% of the total species recorded. It was observed that most of the mollusc species of the upper Brahmaputra Basin are either in the ‘Least Concern’ or ‘Data Deficient’ category of the IUCN Red List; except for Lymnaea ovalior (Annandale & Prashad, 1921) and Sphaerium austeni Prashad, 1921 assessed as ‘Vulnerable’ and ‘Near Threatened’, respectively. A significant trend in the diversity in terms of species richness and composition was observed across the sampling stations of the northern basin and southern basin of the river Brahmaputra.