Gastropod Assemblages Research Articles

Ecological impact of freshwater invaders: A case study of gastropod assemblages in karstic spring ecosystems

Ecological impact of freshwater invaders: A case study of gastropod assemblages in karstic spring ecosystems

Reconstructing the South American Miocene puzzle: An integrated analysis of the Paraná Formation (Argentina)

In recent decades, Miocene marine transgressions in South America have sparked ongoing debates concerning their boundaries, number of events, regional connectivity, and the existence of an epicontinental sea formed during the Andean orogeny. The bed-by-bed analysis of the Late Miocene Paraná Formation deposits in Entre Ríos Province (Argentina) allow defining six facies associations: (i) beach ridge, (ii) tidal inlet channel and washover fan, (iii) outer estuarine bioherms, (iv) central estuary, (v) tidal bar and sandflat, and (vi) tidal mudflat and creek deposits. Architectural and stacking pattern analyses reveal transgressive-regressive sequences typical of the coastal strip, encompassing shallow marine to estuarine sub-environments. The analysis identified diverse ecological guilds, including bivalve and gastropod assemblages in bioherms, and crustacean traces in tidal flats. Regressive units are characterized by wave-dominated shoreface deposits, while transgressive units comprise fine-grained estuarine deposits interbedded with bioclastic sandstones and storm deposits. The paleoenvironmental and paleoecological data indicate normal salinity marine environments with macroinvertebrates and estuarine components and suggesting tropical brackish conditions. Plant remains point to a range of vegetative communities, including mangroves, palm forests, grasslands, humid riparian forests, and dry upland forests, reflecting tropical to subtropical and humid to semiarid environments. This study concludes that the Paraná Formation correspond to a third-order transgressive system tract influenced by the Miocene Paranaense Sea. The basin-scale implications suggest that the distal Chaco-Paraná basin was affected by eustatic changes due to its low accommodation and topographic relief. The Chaco-Paraná foreland basin's evolution was driven by interactions between tectonic, climatic, and eustatic processes. The comprehensive analysis of sedimentary and fossil records provides a detailed paleogeographic reconstruction of the Miocene marine transgression in southern South America.

Gastropod assemblages in the harsh environment of Mediterranean Dinaric karst intermittent rivers

Freshwater snails inhabit a wide range of freshwater habitats, including the intermittent ones, specific adaptations enabling them to survive the dry phase for an extended period of time. Despite an increasing scientific interest in biota occurring in intermittent freshwater habitats, our knowledge about environmental factors shaping freshwater gastropod assemblages in such habitats is still poor. Therefore, this study aimed to assess gastropod assemblage composition in four karst intermittent rivers in the Mediterranean during the lotic phase, compare gastropod taxa richness and abundance among the rivers, and determine their relationships with environmental variables. A total of six taxa was recorded, with each river harbouring a unique, species-poor (up to three species) assemblage. Gastropod assemblages were influenced by the physico-chemical water properties, especially the concentration of dissolved oxygen in water, conductivity, and chemical oxygen demand. Our results provide a basis for further research on freshwater snail assemblages in the Mediterranean karst intermittent rivers, as the need to protect these vulnerable ecosystems and develop adequate monitoring practices becomes imperative due to climate change and anthropogenic pressures.

Cenomanian gastropods of Bellezma-Aures mountains (Batna, NE Algeria): Taxonomy, palaeoecology and palaeobiogeography

Twenty-one gastropod species are identified from the Cenomanian deposits of Bellezma-Aures mountains, eastern Saharan Atlas, Algeria. Among of these taxa four species [Tylostoma elevatum (Shumard), T. torrubiae Sharpe, Nerinea olisiponensis Sharpe and Calliomphalus orientalis Douvillé] are recorded for the first time in the mounts of Batna. These gastropods taxa are found scattered in the ‘Marnes de Smail’ Formation and their community changes can be attributed to minor sea-level fluctuation associated to variation in the sedimentation rate and hydrodynamics. Furthermore, the palaeobiogeographic distribution of these gastropod assemblages display tethyan affinity and their subsequent faunal exchange in that time interval.

Comparison of alien Robinia pseudoacacia stands with native forest stands across different taxonomic groups

There is much knowledge about the impact of non-native Robinia pseudoacacia on native ecosystems, but mostly it is related to one group of organisms. In this article, we provide an analysis of the impact of R. pseudoacacia on the surrounding biota with a broader scope in a model area with homogeneous abiotic conditions compared and analysed by the twin plots method. Microclimatic conditions and the changes in the species composition of vegetation, terrestrial gastropods, carabid beetles, bats, and acoustic diversity were analysed. The planted Robinia stands were always brighter and warmer and had lower canopy closure than the control plots in the native floodplain forest. More nitrogen and phosphorus were recorded in the soil of the Robinia stands. The floristic composition changed the most based on the planting of Robinia trees. Compared to those in the adjacent floodplain forest, more heliophilous neophytes, archaeophytes and grasses were found. Assemblages of gastropods and carabid beetles were less affected by the planting of Robinia trees and more by the microclimatic conditions of the studied locality. The number of recorded bats and acoustic diversity were higher in native floodplain forests due to food and shelter options.All results show that the planting of Robinia trees changes the microclimatic conditions and species composition of forest stands. The warmer and less humid environment under Robinia stands is not desirable in the face of ongoing climate change. The alien (including invasive) and ruderal plant species in the understorey are supported due to the more favourable brighter conditions and nitrogen fixation in the soil. Additionally, the other groups of organisms react negatively to changes under Robinia trees in terms of microclimatic conditions, food and shelter sources. Therefore, forest managers, policy-makers and conservation workers should choose stratified management when deciding whether and where to plant R. pseudoacacia.

The heterobranch subgenusTrochactaeon(Trochactaeon) in the Campanian (Late Cretaceous) of the northern Arabian Platform and its paleoenvironmental and paleobiogeographic implications

AbstractActeonellids were one of the most significant groups of marine macro-invertebrates in the Late Cretaceous biota of the Tethyan Realm. They were common faunal elements associated with Cretaceous carbonate platform communities most notable for their abundance of rudist frameworks and thrived in coeval lagoons. The Upper Cretaceous fossil-bearing Karababa Formation, cropping out in southeastern Turkey, yields a remarkable assemblage of acteonellid gastropods and rudists. Cretaceous gastropods from sedimentary successions in Turkey barely have been studied over the past 80 years. The subgenusTrochactaeon, a very successful and widespread taxon of heterobranch gastropods within the family Acteonellidae, dominated acteonellid assemblages throughout the Late Cretaceous. In the present work, we present the first record ofTrochactaeon(Trochactaeon)giganteus subglobosusfrom Turkey. It is from a single lower Campanian bed in the upper part of the Karababa Formation of the Gölbaşı region (south of Adıyaman), corresponding to the northwestern part of the Arabian Platform. This record complements information on the temporal and spatial distribution ofTrochactaeonat the southern margin of the Tethyan Ocean during the last part of the Cretaceous Period. This discovery increases the documented diversity of the paleofauna from the Upper Cretaceous succession in southeastern Turkey and provides new insights into the paleoenvironment of the carbonate ramp of the northern Arabian plate, and the paleobiogeography of Campanian gastropods in general.

The Lower Pliocene marine gastropods of Santa Maria Island, Azores: Taxonomy and palaeobiogeographic implications.

In this work, all the Lower Pliocene gastropod assemblages of Santa Maria Island are revised. These all form part of the Touril Complex. Seventy-seven species are identified representing 61 genera. Two species are described as new: Bittium miradouroense nov. sp. and Erato mayeri nov. sp. The name Tritonium secans Bronn in Reiss 1862 is considered a junior subjective synonym of Monoplex comptus (A. Adams, 1855). Pleurotoma perturrita Bronn in Reiss 1862 is considered a junior subjective synonym of Crassopleura maravignae (Bivona, 1838). However, due to the difficulties in collecting from these deposits, this is likely to be a considerable underestimate of the original diversity of local Early Pliocene gastropod faunas. The assemblage reflects a fully tropical with mean annual sea surface temperatures (SSTs) estimated about 3.7°C to 6.3°C higher than the present-day 20.6°C, and with mean monthly SSTs ranging from 20°C to 28°C, with six months with mean SSTs over 24°C. The assemblages all represent relatively shallow water, fully saline marine environments. At genus level the assemblage is typical of that seen in the tropical Mediterranean-West African Palaeobiogeographical Province during the early Pliocene (MPPMU1; roughly equivalent to the Zanclean and earliest Piacenzian). At species level, 35% of the species taxa found in Santa Maria are also found in the Mediterranean during MPPMU1. There is a much weaker association with the northern warm temperate Pliocene Boreal-Celtic Province, with only 17% of species occurring in both. Moreover, most of those are ubiquitous European species with both wide geographic and stratigraphic distributions. The assemblage is relatively endemic (29%) suggesting that the Azorean subprovince/ecoregion, which is recognised today, was already in place in the Lower Pliocene. A small number of tonnoidean species found in Santa Maria are species known to have had an amphiatlantic distribution during the Pliocene, and for Distorsio mcgintyi Emerson & Puffer, 1953, a well-known and widely distributed tropical American Atlantic species from the Early Miocene to present-day, its presence in Santa Maria marks the most easterly range expansion for the species, as today is not found in the Azores.

Shell and associated operculum in Teiichispira (Macluritidae: Gastropoda) from the Early/Middle Ordovician of the Argentine Precordillera

AbstractTwo species of Teiichispira Yochelson and Jones reported from the Early/Middle Ordovician marine deposits of the San Juan Formation in the Argentine Precordillera are described. The new species Teiichispira teresae n. sp. is a component of the Early/Middle Ordovician marine gastropod assemblage in the studied region; Teiichispira argentina (Kayser), previously known from the San Juan Formation, is described with a complete teleoconch and associated operculum. The opercula of both Teiichispira species are complete and preserved in life position associated with the shell of T. argentina. The unguiculate morphology of the operculum is here interpreted as a mechanism for increasing the shell weight and ensuring anchoring to the substrate in a more or less fixed mode of life for Teiichispira, and as protection. The new occurrence of Teiichispira provides new taxonomic data on early Paleozoic marine gastropods in Argentina and testifies to a wide paleobiogeographical distribution for the genus, restricted to tropical and subtropical regions during the Early/Middle Ordovician.UUID: http://zoobank.org/8ee48319-b17a-4d15-a7d4-99cc9bb1dc42

Quaternary coral, coralline algal and vermetid assemblages as sea-level indicators: a review

Corals, coralline algae and vermetid gastropods are indirect (marine limiting) relative sea-level (RSL) indicators. The precision in sea-level reconstruction based on fossils of those organisms depends on the probable palaeodepth in which they grew. Constraining such palaeodepth depends, in turn, on the available information about the habitats of their living counterparts. Diverse genera, species and species assemblages of corals, coralline algae and vermetid gastropods have historically been proposed as reliable indicators of narrow, shallow depth ranges. However, the increased information on depth distribution of marine benthos in the last two decades has challenged some early assumptions about depth ranges of taxa considered diagnostic of precise palaeodepths. Here, the authors test the reliability of coral, coralline algal and vermetid assemblages that have been extensively used in RSL reconstructions in the light of data from Ocean Biogeographical Information System (OBIS) and other recently published data. In the Indo-Pacific province, these data support the use of the robust-branching and the shallow, high-energy encrusting coral assemblages with a 0 to 10 m uncertainty. In both cases many component species have unimodal distributions and both median and average water depths are shallower than 10 m. The reliability of these coral assemblages as indicative of shallow water depths is strengthened when corals are encrusted by thick plants of the coralline alga Porolithon gr. onkodes. According to OBIS data, coralline algae of this species group in the Indo-Pacific are restricted to very shallow waters (95% probability of occurrence shallower than 0.2 m and in 99.6% of records shallower than 6 m). However, such a narrow depth range and the overall scarce data on coralline algal species in the OBIS database are questionable due to difficulties of coralline algal species identification with the naked eye. A comprehensive survey of the modern distribution of coralline algae at One Tree Reef (southern Great Barrier Reef) indicates that P. gr. onkodes has a log-normal distribution with median depth of less than 5 m and 95% of occurrence probability of thick crusts (> 0.2 mm) shallower than 8.8 m. Data on modern distribution of vermetids are scarce. In the OBIS database, vermetid species are reported from relatively wide depth ranges. However, relatively high densities (> 10 individuals per m2) on coral and coralline algal surfaces only occur from above mean low tide to some 6 m depth. In the Western Atlantic-Caribbean province Acropora palmata is the most precise RSL marker and no additional components of fossil assemblages improve its palaeodepth information. The confident use of coralgal and vermetid assemblages as RSL indicators relies on the identification of fossil corals and coralline algae at the species or species-group level. The scarcity of available data highlights the need for further studies on distribution of coralline algal species and vermetid in modern coral reefs from a variety of oceans and reef settings.

Bi- and three-dimensional fractal analysis of the brown seaweed Gongolaria montagnei and their relationship with gastropod molluscs assemblage

Habitat complexity is one of the main influences on biodiversity in marine environments, particularly in coastal areas where foundation seaweeds provide substrate for highly diverse communities. We studied the 2D and 3D fractal dimensions of Gongolaria montagnei (Fucales) over the vegetative season and examine their relationship with the abundance, species richness and morpho-functional groups of the gastropod associated. Overall, the 3D fractal analysis method used here better describes seaweeds structural complexity compared to the traditional 2D fractal analysis, as highlighted by the higher relationship with gastropod assemblage associated to the alga in terms of abundance, number of species and morpho-functional groups. We propose this new method as a valuable tool for understanding the relationship between seaweeds and associated fauna, which is critical for gaining a better understanding of the role that algal species play in a specific habitat and the consequences of their loss.

Towards a Sustainable World: Diversity of Freshwater Gastropods in Relation to Environmental Factors—A Case in the Konya Closed Basin, Türkiye

The Konya Closed Basin (KCB) in Türkiye plays a key role in agricultural production and freshwater supply. However, the basin is impacted by humanly derived nitrogenous compounds and toxic metals. Keeping the water quality at a potable level in the basin is compulsory. This study was part of a project yielding monitoring of water quality in KCB in accordance with the Water Framework Directive (2000/60/EC). Eleven stations, except Beyşehir Lake and Mamasın Dam, were sampled for the first time for freshwater molluscs. Community structure indexes and multivariate statistical analyses were applied to determine the microhabitats of gastropods and their responses to environmental changes. The structure and distribution of gastropod assemblages differed depending on total phosphate, total nitrogen, dissolved oxygen, and pH. This study revealed that most of the gastropods in KCB are relatively tolerant to biodegradable pollution. However, there is a strong observed decline in population size requiring intensive future monitoring; measures have to be taken to preserve the remaining populations. Two endemic species need an urgent action plan to protect their habitats: Theodoxus anatolicus of Çeltik Canal and Bithynia pseudemmericia of Beyşehir Lake; a re-assessment of their extinction risk according to the IUCN rules is needed (2022). The results of this study will be useful for comparison with future studies to document potential improvements or continued ecological regression in the quality of aquatic ecosystems in the watershed.

Distributional Patterns of Gastropoda Upstream and Downstream of Bujagali Hydropower Project along the Upper Victoria Nile

To better understand the gastropod community dynamics of fresh water snails in the Upper Victoria Nile (UVN), the spatial and temporal abundance changes in gastropod assemblage were assessed biannually from April 2006 to April 2021 at three transects. Biannual abundances of gastropoda were obtained by a ponar grab to examine changes in their community structure in relation to Bujagali Hydropower Project (BHP). The gastropod community consisted of nine speciesbelonging to five families (Thiaridae, Viviparidae, Ampullariidae, Bithyniidae and Planorbidae). Pulmonate species registered five species <i>(Anisus natalensis, Gyraulus sp., Segmentorbis sp., Bulinus sp. and Biomphalaria chaonomphola)</i>. Two of the pulmonates <i>(Bulinus sp. and B. chaonomphala)</i> are schistomiasis vectors. The pulmonates <i>(A. natalensis, Gyraulus sp., Segmentorbis sp.)</i> were rare and intermittently occurred with abundances up to 47 ind.m-2. Four prosobranch species <i>(Gabbia humerosa, Pila ovata, Melanoides tuberculata and Bellamya unicolor)</i> were encountered. Of these prosobranchs, <i>P. ovata</i> was the rarest while <i>M. tuberculata</i> and <i>B. unicolor</i> were the commonest. The gastropod community in the UVN was characterised by prosobranchs-dominated abundance which over the 16-year monitoring period often registered peak densities of > 1000 ind.m2. The inter-site Percent Similarity Index (PSI) (94-100%) indicated a high degree of similarity of gastropod community across the sites.

What physical habitat factors determine the distribution of gastropods in neotropical headwater streams?

Freshwater gastropods play a pivotal role in the structure and functioning of freshwater ecosystems, but despite their importance, there are still gaps in their ecology. Our goal was to understand what physical habitat factors are the most important for the distribution of freshwater gastropods in headwater stream ecosystems in the Neotropical Savanna and provide a baseline for conservation and management efforts for freshwater gastropods in this biome. We identified five taxa, each with different environmental prefferences. Littoridina presence related negatively with stream slope, Biomphalaria presence related positively with total dissolved solids and the proportions of cobble, fine sediment and organic matter. Gundlachia presence correlated positively with elevation and the proportion of pools in the site. Physa presence related negatively with total dissolved solids and positively with alkalinity. Melanoides tuberculata presence correlated positively with the proportion of coarse gravel. Our results highlight the challenge for protecting native freshwater gastropod assemblages (and managing non-native invasive species), because environmental preferences vary widely amongst taxa and most are vulnerable to common anthropogenic disturbances.

Gastropod Assemblages Associated with Habitat Heterogeneity and Hydrological Shifts in Two Shallow Waterbodies

We aimed to determine the effects of water level and habitat heterogeneity on gastropod fauna in the littoral zone, and the differentiation of functional feeding guilds (FFG) of gastropods. Two periods were analyzed: 2012 (low water level, LWL) and 2013 (high water level, HWL) in the littoral zone of two shallow waterbodies (Sutla backwater, NW Croatia). Waterbody S1, covered with Ceratophyllum demersum, was sampled in the macrophyte stands, and the littoral benthal area, while waterbody S2, without macrophytes, was sampled only in the littoral benthal area. It was observed discovered that among the macrophyte stands in S1, gastropods were significantly more abundant during LWL. The same trend was observed in the littoral benthal area of S2. In contrast, gastropod abundance was higher in the littoral benthal area of S1 during HWL. Comparing gastropods in the two waterbodies, the abundance in S1 was ten times higher than in S2. The most abundant species was Gyraulus parvus, which accounted for 51–92% of the gastropods observed among the macrophytes of S1 and 86% in the adjacent benthic zone. Among the FFG groups, grazers (particularly those feeding on gymnamoebae and rotifers) had the largest proportion, followed by shredders feeding on small pieces of macrophytes. In our research, we indicate the important role of microhabitat diversity and submerged macrophytes as a rich food source for gastropods and safe shelter from predators.

Gastropod assemblages associated with Himantothallus grandifolius, Sarcopeltis antarctica and other subtidal macroalgae

AbstractGastropods are an important component of subtidal Antarctic communities including in common association with macroalgae. Nonetheless, limited data exist detailing their abundance and distribution on macroalgal species. This study documents the abundance and species composition of gastropod assemblages on the two largest, blade-forming Antarctic macroalgae, Himantothallus grandifolius and Sarcopeltis antarctica, sampled across two depths (9 and 18 m) at four sites for each species off Anvers Island, Antarctica. Gastropods were also enumerated on Desmarestia anceps, Desmarestia antarctica and Plocamium sp. but were not included in the main analyses because of small sample sizes. There were major differences between the gastropod assemblages on deep vs shallow H. grandifolius and S. antarctica with much higher numbers of individuals and also greater numbers of gastropod species at the greater depth. Differences between the gastropod assemblages on H. grandifolius and S. antarctica across sampling sites were apparent in non-parametric, multivariate analyses, although depth contributed more than site to these differences. Within common sites, assemblages on H. grandifolius were significantly different from those on S. antarctica at 18 m depth but not at 9 m depth, indicating that the host species can be but is not always more important than site in influencing the gastropod assemblages.

Middle Ordovician (Whiterockian) gastropods from central Sonora, Mexico: affinities with Laurentia and the Precordillera

AbstractThe Lower–Middle Ordovician (Ibexian, Whiterockian) sedimentary rocks exposed at Rancho Las Norias includes the informally named Las Norias formation, which consists of an intercalation of carbonate and clastic sediments with abundant marine fauna. These deposits occur as the most austral sedimentary rocks of Ordovician age for Laurentia, providing a critical link to understand the distribution of Ordovician marine faunas of North America. An investigation of the gastropod fauna from the upper portion of the Las Norias formation, Sonora, Mexico, is undertaken for the first time. The gastropod assemblage includes Maclurites acuminatus, ?Monitorella sp., Lecanospira sp., Malayaspira aff. M. rugosa, Lophospira perangulata, and Hormotoma? sp. This assemblage indicates a paleogeographic relationship with Laurentia, including the USA (Nevada), Canada (British Columbia, Newfoundland), Greenland, and the Argentine Precordillera.

Comparative study of the taphonomic history of Holocene gastropods and ostracods of the high basin of the Salado river, Buenos Aires, Argentina

Gastropods and ostracods are widely used in Quaternary paleoenvironmental reconstructions but the taphonomic studies that should precede them are not as common. In this paper we compare the taphonomic information obtained from assemblages recovered in Holocene fluvial sequences of the Salado River basin (Buenos Aires, Argentina) and analyze the changes or similarities between species, localities and stratigraphic units. Using taphonomic grades, gastropod shells were cataloged based on three attributes: fragmentation, discoloration and dissolution. For ostracods, discoloration and dissolution together with the population structure (adults-juveniles A/J, valves-carapace V/C and male-female ratios) were analyzed. For gastropods, Heleobia parchappii, Biomphalaria peregrina and Succinea meridionalis showed similar preservation patterns, and Miradiscops brasiliensis showed least evidence of alteration. In ostracods, these patterns varied among species. For V/C ratio, 7% of assemblages were formed only by valves, 82% were dominated by valves and 11% were dominated by carapaces. Fragmentation and population structure allowed autochthonous and allochthonous associations to be distinguished. Gastropod assemblages with low levels of fragmentation were recovered mainly from the uppermost levels of the stratigraphic profiles. For ostracods, the A/J ratio showed that 52% of the assemblages were dominated by adults with most ontogenetic stages represented and 29% retained their original population structure suggesting they would be autochthonous associations, whereas 19% of the assemblages were dominated by juvenile valves therefore assuming allochthonous associations. Our results indicate that taphonomic analysis is an effective tool that allows identifying autochthonous assemblages, which are the most reliable for robust paleoenvironmental reconstructions.

Phylogenomic resolution of the root of Panpulmonata, a hyperdiverse radiation of gastropods: new insight into the evolution of air breathing.

Transitions to terrestriality have been associated with major animal radiations including land snails and slugs in Stylommatophora (>20 000 described species), the most successful lineage of 'pulmonates' (a non-monophyletic assemblage of air-breathing gastropods). However, phylogenomic studies have failed to robustly resolve relationships among traditional pulmonates and affiliated marine lineages that comprise clade Panpulmonata (Mollusca, Gastropoda), especially two key taxa: Sacoglossa, a group including photosynthetic sea slugs, and Siphonarioidea, intertidal limpet-like snails with a non-contractile pneumostome (narrow opening to a vascularized pallial cavity). To clarify the evolutionary history of the panpulmonate radiation, we performed phylogenomic analyses on datasets of up to 1160 nuclear protein-coding genes for 110 gastropods, including 40 new transcriptomes for Sacoglossa and Siphonarioidea. All 18 analyses recovered Sacoglossa as the sister group to a clade we named Pneumopulmonata, within which Siphonarioidea was sister to the remaining lineages in most analyses. Comparative modelling indicated shifts to marginal habitat (estuarine, mangrove and intertidal zones) preceded and accelerated the evolution of a pneumostome, present in the pneumopulmonate ancestor along with a one-sided plicate gill. These findings highlight key intermediate stages in the evolution of air-breathing snails, supporting the hypothesis that adaptation to marginal zones played an important role in major sea-to-land transitions.

A low-diversity Peruvispira-dominated gastropod assemblage from the Permian Ratburi Group of Central Thailand

Permian gastropods from Thailand have been extensively studied over the last few years. The earliest known fossil collection was recovered in 1967 but has never been figured or described. Here, we document this historically important gastropod assemblage excavated from the upper-Lower to Middle Permian Ratburi Group of Khao Mang Lat in the Ban Kao District of Kanchanaburi Province, Central Thailand. The material comprises approximately 200 specimens, almost all of which represent a new species, Peruvispira kanchanaburiensis sp. nov. (Goniasmatidae), together with a single individual of Orthonychia sp. (Orthonychiidae = Platyceratidae). This exceptionally low-diversity community is unusual in comparison to Permian gastropod faunas reported from elsewhere, and could reflect either a low temperature palaeoenvironmental setting or priority effects resulting from early establishment of planktotrophic larvae within the local habitat. Baran Karapunar [karapunar@snsb.de ], SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, 80333 München, Germany, and Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany; Alexander Nützel [nuetzel@snsb.de ], SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, 80333 München, Germany, and Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany, and GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany; Chatchalerm Ketwetsuriya [ketwetsuriya.c@gmail.com ], Department of Earth Sciences, Faculty of Science, Kasetsart University, 10900 Bangkok, Thailand.

A predatory gastropod as the potential biological control agent of the Korean invasive mussel, Mytilus galloprovincialis (Lamarck, 1819)

The classical biological control, which is the intentional introduction of exotic species to manage the biological invasion, is the standard measure if the human-mediated management is no longer effective. This method, however, involves a latent risk that the introduced exotic species brings about the nontarget effect on indigenous native species. Applying the native natural predator is the best alternative to control the invasive alien species without the substantial change into the ecosystem of the area invaded. Here, we introduced an indigenous Korean muricid gastropod Reishia bronni (Dunker, 1860), a potential natural predator of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819), a well-known invasive alien species successfully settled down in Korea. In the biomonitoring survey on the Korean ports of the east coast between 2007 and 2011, we have observed the spread of R. bronni within the Mytilus galloprovincialis community. The observed decrease of the mussel density around the gastropod assemblage led us to the idea that R. bronni is the natural predator of M. galloprovincialis . In order to clarify such a predator-prey interaction between both species, we performed a field observation from two Korean ports in August 2012, keeping R. bronni and M. galloprovincialis individuals together into the cages for 18 days. Then, we counted the number of latter ones consumed and estimated the average time spent feeding per individual of R. bronni . We observed the positions of the drill holes made on the consumed shells by it. Our results showed that R. bronni is the active natural predator of M. galloprovincialis with the high feeding intensity and the unique foraging behavior targeting the lateral margin of the shell, so-called “Marginal drilling”. Therefore, we could suggest the possibility that R. bronni can be applied to control the mass spread of M. galloprovincialis .