Apple Snail Pomacea Research Articles

The population of Solenopsis sp. (Hymenoptera: Formicidae) in four condition of rice Held embankment

Fire red ants (Solenopsis sp.) as the predators often found in rice fields. Although many farmers not yet know well this potential insects, in Philippines, this adaptive predator has been used to control golden apple snail with satisfying results. In a period of two days, predatory ants able destroyed 50% the eggs of golden apple snail Pomacea canaliculata attached to the leaves of rice plants. The purpose of the research is to study the effect of characteristic differences vegetation of rice field bund to the diversity of ants in the habitat. Research data collection was conducted in Manggala district, Makassar. Identification and observation of ants species was held at the Pest Laboratory, Department of Plant Pests and Diseases, Faculty of Agriculture, Hasanuddin University, Makassar. The research was held from March to May 2018. The results was showed that the bund contain banana tree vegetation had the highest Solenopsis sp. population with 288 individuals. The lowest on the embankment with broad leaf vegetation only 29 individuals. The highest number of individual ants was found in Solenopsis sp. with 353 individuals, then the lowest is Tetramorium sp. with 2 individuals. The difference conditions of vegetation bund showed greatly affects in the number of ants due to differences in the conditions needs of each ant species for their suitable habitat.

Effect of Shrimp Feed Supplemented with Astaxanthin on Golden Apple Snail Pomacea diffusa

Popularmente conhecidas como ampulárias, esses moluscos gastrópodes são usualmente cultivados como organismos ornamentais pelo mundo. A coloração desses animais ornamentais é um dos pontos que atrai os seus admiradores e estimula sua aquisição no mercado. O pigmento mais difundido como suplemento para intensificação de cor em organismos aquáticos é a astaxantina. Ainda não existem rações específicas para a ampulária reforçando a necessidade de testar alternativas de alimentos e suplementos que melhorem o desempenho produtivo e a atratividade do animal. Os objetivos desse estudo foram mensurar a capacidade de acumulação de astaxantina sintética em diferentes níveis de inclusão na dieta de Pomacea diffusa, sua influência na concentração do pigmento e nos índices zootécnicos ao final do cultivo. E em paralelo verificar a influência da mudança da dieta de ração de peixes para ração de camarão na condição corporal dos moluscos em comparação com o início do trabalho. As ampulárias alimentadas com ração comercial extrusada para camarão marinho tiveram baixos índices de conversão alimentar (126,7 ± 18,3), altos índices de eficiência alimentar (126,7 ± 18,3%) e fator de condição (1,0 ± 0,14) acima da média inicial (0,90 ± 0,17), o que demonstra que esse alimento pode ser utilizado para seu cultivo. A suplementação dietética de astaxantina sintética não resulta em aumento significativo da concentração desse pigmento na musculatura desse molusco (P˃0,05). Palavras-chave: Ampulária. Moluscos. Gastrópodes. Pigmentos. Carotenoides. Abstract Known as apple snail, these gastropods are popular as aquarium pets around the world. The bright color of these animals is one of the key points that attract their attention in the ornamental aquaculture, where deep-colored animals are well appreciated. Astaxanthin is the most widespread color enhancing pigment used as a food supplement for aquatic organisms. There is no specific commercial food for apple snails, emphasizing the need to search for food alternatives and supplements that improve their performance and attractiveness. The objectives of this study are to measure the synthetic astaxanthin accumulation capacity of Pomacea diffusa at different levels of diet supplementation, and the effect on pigment concentration and zootechnical indexes at the end of the culture. It was also aimed to verify the effect of the diet change from fish food to extruded shrimp food on the mollusks’ body condition. Apple snails fed with commercial shrimp ration had low feed conversion rates (0.81 ± 0.13), high food efficiency (126.7 ± 18.3%), and condition factor (1.0 ± 0.14) above the initial average (0.90 ± 0.17), demonstrating that this might be an advantageous alternative food. Dietary supplementation with synthetic astaxanthin did not result in a significant concentration increase of this pigment in muscle tissue of these mollusks (P˃0.05). Keywords: Aquaculture. Mollusks. Gastropods. Pigments. Carotenoids

First Taxonomic Records of Epizoic Freshwater Algae on Golden Apple Snails (Pomacea canaliculata Lamarck) from Rice Paddies in Laguna (Philippines)

In rice paddies where hard substrate is considered as a limiting resource, the hard shell of mollusks can serve as a primary settling space of algal epibionts. The study presents the first taxonomic survey to report and describe epizoic algae in freshwater snail – golden apple snail (GAS) (Pomacea canaliculata Lamarck) – found in agricultural areas. A total of 17 microalgal taxa belonging to 12 orders, 16 families, and 17 genera were taxonomically identified and described from the collected samples, all of which are considered new distributional records of microalgae in the Philippines. The study shows Cyanobacteria (six species) as the main group of epizoic microalgae present in shell surfaces of the mollusk, followed by Bacillariophyceae (four species), Chlorophyceae (three species), Zygnematophyceae (two species), Trebouxiophyceae (one species), and Euglenophyceae (one species). Also, the survey reported the occurrence of a photosynthetic euglenoid, Phacus hamatus Pochmann, described for the first time in the Philippines. Diagnostic descriptions and taxonomic keys are presented to differentiate the epizoic algal taxa associated with GAS. The survey shows important taxonomic records on the composition and species diversity of epizoic algae from freshwater snails found in terrestrial habitats of the Philippines.

Predation by the carrion crow Corvus corone (Passeriformes: Corvidae) on the apple snail Pomacea canaliculata (Architaenioglossa: Ampullariidae) in different locations in Japan

Alien species are exposed to novel species interactions in invaded ecosystems, and predators are important components of biotic resistance against aliens. The apple snail Pomacea canaliculata (Lamarck) (Architaenioglossa: Ampullariidae) was introduced to many countries, and causes severe problems including damage to young rice plants. Biotic resistance against the apple snail is generally weak in modernized rice fields, but carrion crows Corvus corone Linnaeus (Passeriformes: Corvidae) are observed to prey on apple snails. Thus, we investigated predation on the apple snails by the crows in three locations in Japan, and compared predation pressure, prey size, and predation methods among locations and different months/years in Ehime Prefecture. Carrion crows preyed on relatively small snails among subadults and adults in paddy fields. Predation rate within 1.2 m from the levee was as high as 87.1% in Ehime, 14.1% in Fukuoka (both in 2 days), and 1.1% in Nara (in 4 days). Thus, predation by crows is considered to be effective in reducing the density of snails in paddy fields in Ehime and possibly in Fukuoka. However, the period of predation and the intensity of predation varied from year to year in Ehime over a 3-year study period.

Effects of the molluscicide candidate PPU06 on alkaline phosphatase in the golden apple snails determined using a near-infrared fluorescent probe

We constructed a reaction-based near-infrared fluorescent probe (Niap) to specifically identify alkaline phosphatase (ALP) with fast red fluorescence enhancement. Based on the positive concentration-dependent manner between the fluorescent intensity of the Niap and ALP, probe Niap was used to study the ALP enrichment and variation in golden apple snails (Pomacea canaliculata) exposed to the molluscicide candidate PPU06. After treatment with different concentrations of PPU06 over various times, three organs of the surviving snails, liver, stomach and plantaris, were frozen and sectioned for fluorescent imaging experiments. With increased PPU06 concentration, red fluorescence substantially increased in the liver and reached a maximum within 24 h when the PPU06 concentration was 0.75 mg/L. No obvious changes in the stomach or foot plantaris were found. It showed PPU06 caused liver injury and stimulated the increase of ALP in the liver of P. canaliculata. This study demonstrates a rapid ALP fluorescent identification method that can be used to study the effects of PPU06 on P. canaliculata. It also provides optical evidence that may aid in the discovery of new chemistry for snail control.

Notes on the foraging and feeding behaviours of the Asian Openbill Stork (Anastomus oscitans)

The foraging and feeding behaviours of the Asian Openbill Stork (Anastomus oscitans) were observed in several paddy fields in Thailand, on food items not previously reported. Foraging and feeding techniques of the storks were similar to those described in the literature, except at one site where a peculiar new foraging behaviour was observed. Here, the storks fed on exotic Golden Apple Snails (Pomacea canaliculata) by using their bills to puncture the shells for extracting the soft snail bodies. The shells of large snails discarded by storks tended to be more damaged than those of small snails, due to the difficulty of extraction. Analyses of stork’s droppings and their regurgitated food showed that the bulk was of plant materials and shelled snails (mainly P. canaliculata and Filopaludina spp.). Adult storks tended to consume the whole soft bodies of the snails, including viscera, and sometimes the entire snails, including with their hard shells and opercula still attached. Although the storks could feed potentially on the entire snail body, the birds were seen to discard the male’s testes and female’s albumen glands of P. canaliculata at these feeding grounds, also evident in their regurgitates. Crushing of snail shells was not evident, but sometimes, pounding the shell and/or swallowing the entire shell and its operculum were supported by observations.

Internal standard application strategies in mass spectrometry imaging by desorption electrospray ionization mass spectrometry.

We developed a model case study to evaluate three internal standard (IS) application strategies (methods I-III) using the psycholeptic phenobarbital (PB) and the isotopically labelled IS phenobarbital-D5 (PB-D5) from in vitro dosed tissues of the golden apple snail (Pomacea diffusa) by desorption electrospray ionization mass spectrometry imaging (DESI-MSI). In method I, the IS was deposited as microspots on top of 10 μm thick snail tissues; in method II, a thin IS film was applied; and in method III, the IS was spiked into the DESI solvent spray. DESI-MSI analyses were performed using a Thermo LTQ mass spectrometer equipped with a custom-built DESI source and two-dimensional moving stage. PB (m/z 231) and PB-D5 (m/z 236) were monitored in selected ion monitoring mode between m/z 227 and 239. The analytical performance of two IS strategies (methods I and II) in DESI-MSI was evaluated based on an intra- and inter-day precision assay, an accuracy assessment, and statistical analysis. In the inter-day DESI-MSI assay, method I exhibited better precision (6.5%-7.4%) than method II (10.7%-17.6%) between 10 and 100 ng/μL. In the accuracy assessment, PB quality controls of 75 ng/μL were back-calculated as 71 ± 4 and 83 ± 9 ng/μL, resulting in relative errors of -5% and 11% for methods I and II, respectively. Method III did not work under the experimental design and was not evaluated. Three IS application strategies were investigated and compared for a routine quantitative DESI-MSI approach. Methods I and II were not statistically significantly different as shown by a Bland-Altman plot, suggesting that these two methods can be used interchangeably. However, method III requires further research for future quantitative DESI-MSI analyses.

Shell morphology of golden apple snails (Pomacea canaliculata) from several rice fields in Bali, Indonesia

Golden apple snail (Pomacea canaliculata) has wide adaptability and rice fields are ones of the habitats for the snail. Golden apple snail has phenotypic variations. This study conducted to determine the morphology of golden apple snail from several rice fields in Bali, Indonesia. Samples were taken at twelve locations in three districts. Three rice fields were taken in each location. Samples were taken in quadrate plot of 1x1m at four points each rice field. The morphological of the golden apple snail samples were observed. The results showed that the golden apple snail shells found in all locations has a variety of colors. The color was yellowish to dark brown. The shell also has a shell band and the shell band vary in their appearance. The color of the shell band was more visible on the darker shell. Range of shell heights found in all locations was 8.7-61.5 mm. Most of the golden apple snails found in all location was adult snails.

Effects of co-occurrence of invading Procambarus clarkii and Pomacea canaliculata on Vallisneria denseserrulata-dominated clear-water ecosystems: a mesocosm approach

Single invaders often substantially alter ecosystems, but the potential impacts by multiple invaders remain understudied. The golden apple snail (Pomacea canaliculata) and the red swamp crayfish (Procambarus clarkii) are two widespread coinvaders. To test the effects of co-occurrence of the two species on a clear-water macrophyte state, we performed a 20-day experiment in 16 mesocosms (4 contained only two snails, 4 contained only two crayfishes, 4 contained two snails and two crayfishes, and 4 controls). Comparing with the control, the leaf length, number, and biomass of Vallisneria denseserrulata had decreased in the snail-only and crayfish-only treatments. In the crayfish-only treatment, total nitrogen, total phosphorus and total suspended solids had increased compared with the control, while they did not differ between the snail-only and the control treatment. Nutrients and turbidity concentrations did not differ between the snail + crayfish and the crayfish-only treatment, and plant biomass did not differ between the snail + crayfish and the snail-only treatment. These findings suggest that golden apple snails mainly affected the lake ecosystem by plant grazing, while red swamp crayfishes disturbed the sediment by increasing nutrients in the water and through resuspension. These snail and crayfish together had mainly additive effects on macrophyte and the physico-chemical variables studied.

Risk of invasiveness of non-native aquatic species in the eastern Mediterranean region under current and projected climate conditions

Human-induced biological introductions pose a major threat to global biodiversity, and this is especially frequent in the eastern Mediterranean region, which is a globally important biodiversity hotspot area of high conservation value. To predict at which level introduced species in this region might become invasive under current and projected climate conditions, 232 non-native aquatic organisms were screened using the Aquatic Species Invasiveness Screening Kit. Based on receiver operative characteristic curve analysis, thresholds were identified to distinguish between low, medium and high risk species. The “top invasive” (very high risk) species identified were: brown bullhead Ameiurus nebulosus, blue crab Callinectes sapidus, gibel carp Carassius gibelio, Philippine catfish Clarias batrachus, Chinese mitten crab Eriocheir sinensis, bluespotted cornetfish Fistularia commersonii, silver carp Hypophthalmichthys molitrix, silver-cheeked toadfish Lagocephalus sceleratus, half-smooth golden pufferfish Lagocephalus spadiceus, Suez pufferfish Lagocephalus suezensis, signal crayfish Pacifastacus leniusculus, fathead minnow Pimephales promelas, channeled applesnail Pomacea canaliculata, red swamp crayfish Procambarus clarkii, devil firefish Pterois miles and European catfish Silurus glanis. The risk of being invasive of more than half of the screened species increased after taking global warming predictions into account, and several species considered to be globally invasive (cf. high risk) were classified as posing only a medium risk for the eastern Mediterranean region. Region-specific risk screenings, as implemented in this study, are therefore essential for setting priorities in preventative management for the conservation of key biodiversity hotspots and the optimal allocation of resources in view of full risk assessment for the species identified as (very) high risk.

Two Unconventional Metallothioneins in the Apple Snail Pomacea bridgesii Have Lost Their Metal Specificity during Adaptation to Freshwater Habitats.

Metallothioneins (MTs) are a diverse group of proteins responsible for the control of metal homeostasis and detoxification. To investigate the impact that environmental conditions might have had on the metal-binding abilities of these proteins, we have characterized the MTs from the apple snail Pomacea bridgesii, a gastropod species belonging to the class of Caenogastropoda with an amphibious lifestyle facing diverse situations of metal bioavailability. P. bridgesii has two structurally divergent MTs, named PbrMT1 and PbrMT2, that are longer than other gastropod MTs due to the presence of extra sequence motifs and metal-binding domains. We have characterized the Zn(II), Cd(II), and Cu(I) binding abilities of these two MTs after their heterologous expression in E. coli. Our results have revealed that despite their structural differences, both MTs share an unspecific metal-binding character, and a great ability to cope with elevated amounts of different metal ions. Our analyses have also revealed slight divergences in their metal-binding features: PbrMT1 shows a more pronounced Zn(II)-thionein character than PbrMT2, while the latter has a stronger Cu(I)-thionein character. The characterization of these two unconventional PbrMTs supports the loss of the metal-binding specificity during the evolution of the MTs of the Ampullariid family, and further suggests an evolutionary link of this loss with the adaptation of these gastropod lineages to metal-poor freshwater habitats.

An Invader’s Peculiar Trophic Behavior: Diel Fluctuations and Environmental Drivers

AbstractThe trophic ecology of the invasive apple snail Pomacea canaliculata was intensely investigated because of the impacts of its grazing on aquatic vegetation, including crops. However, this freshwater snail also gathers food from the water surface by using a pedal funnel, a distinctive trophic behavior called pedal surface collecting. We investigated the diel fluctuations of this trophic behavior through four whole-day field observations in a stream. We recorded the lowest pedal funnel frequencies during light hours and the highest after sunset, a pattern similar to that of general activity. We evaluated through laboratory experiments the influence of water temperature and velocity, photoperiod, and a possible endogenous rhythm on this behavior. Pedal funnels are formed within the whole temperature range in which this snail is active. The highest pedal funnel formation rates were recorded at 30 °C, but the food captured was the same regardless of temperature. Pedal funnels were not observed at water velocities above 0.12 m·s-1, but below this limit the rate and time spent in funnels remained constant with velocity. Despite the time of day, pedal funnels were scarce under constant artificial light, ruling out an endogenous rhythm. Both in the laboratory and in the stream, the highest levels of pedal funnels were observed during dark periods, probably as a strategy to avoid detection by visual predators. Pedal surface collecting on floating matter could represent an additional impact of invasive apple snails on freshwater ecosystems, but it could also be used for the specific delivery of molluscicides against them.

Golden apple snail (Pomacea canaliculata) as an alternative protein source in Pasupati catfish (Pangasius sp.) fish feed

Abstract. Pertiwi MP, Saputri DD. 2020. Golden apple snail (Pomacea canaliculata) as an alternative protein source in Pasupati catfish (Pangasius sp.) fish feed. Nusantara Bioscience 12: 162-167. Research on efforts to conserve golden apple snail (Pomacea canaliculata) meat has been done. This research aimed to utilize the snail meat as an alternative feed for the Pasupati catfish (Pangasius sp.). The research was carried out from May to August 2020. It began by collecting Pomacea canaliculata by hand sorting then processed into artificial feed/pellets. The research was CRD designed with 5 treatments and 3 replications. Pasupati catfish juvenil measuring 7.4 ± 0.8 cm and weighing 11.7 ± 0.5 g, was maintained for 21 days with a stocking density of 15 individuals/aquarium. Feeding as much as 8% of the biomass with a frequency of feeding 3 times a day at satiation. Variables measured were SGR, L, RP, FCR, and SR. The results showed that feed B produced the best fish growth and could be an alternative fish feed without having a negative effect on growth and feed utilization. Feed B (90% fish meal + 10% Pomacea canaliculata meat meal) had the highest SGR value and was supported by a high PR value and a low FCR value. In addition, there is a difference among variables, despite least significant. ANOVA test also supports the differences between treatments, but HSD test (p<0,05) is not significantly different. This means that the addition of the percentage of P. canaliculata meat meal to the feed does not provide a good performance of the Pasupati catfish. Value of abiotic parameters was ​​to support fish farming.

Exceeding its own limits: range expansion in Argentina of the globally invasive apple snail Pomacea canaliculata

Pomacea canaliculata is a freshwater snail native to southern South America. The aims of this work are to update its distribution in Argentina and to analyze through niche models whether the environmental conditions from its original distribution can anticipate its recently expanded range. Almost all records of P. canaliculata before 1958 (original records) belong to del Plata or connected basins. A quarter of the new present records are located in basins not connected to del Plata, indicating a recent expansion of the distribution range of P. canaliculata in Argentina. Recently colonized areas are mostly environmentally suitable according to the projection of the original distribution model, thus natural barriers were probably the main limits to its distribution in the past. According to the model, many regions outside its original range, including several not yet colonized, are suitable for the establishment of P. canaliculata. Consequently, it is likely that this species will continue establishing new populations in Argentina, especially if fishermen and aquarists continue to move snails to new locations. Our study revealed that an extensive but overlooked invasion is in process in its native range, where the impacts on diversity and ecosystems functioning may differ from those already described elsewhere.

Simultaneous quantification of the lipids phosphatidylcholine, 3-sn-phosphatidylethanolamine, sphingomyelin, and L-α-lysophosphatidylcholine extracted from the tissues of the invasive golden apple snail (Pomacea canaliculata) using UHPLC-ESI-MS/MS

Lipids such as phosphatidylcholine (PC), 3-sn-phosphatidylethanolamine (PE), sphingomyelin (SM) and L-α-lysophosphatidylcholine (LPC) are the major components of biological membranes and play important roles in physiological functions. Here, PC, PE, SM, and LPC were extracted from golden apple snails (GAS, Pomacea canaliculata) and GAS flesh (GASF) using an ethanol/hexane sequential scheme and quantified simultaneously using ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) to evaluate whether the GAS could be the source of the four lipids. Our results suggest that ethanol extracts contained the most crude lipids, and the yield of dry (evaporated) lipids were 3.45 g per 100 g fresh GASF and 1.82 g per 100 g of fresh GAS. Quantification of the lipids using UHPLC-ESI-MS/MS suggested that GAS contained PE, PC, SM and LPC, with SM being the most abundant lipid (after purification: 1.71 and 1.42 mg g−1 dry weight from 100 g of GASF and GAS, respectively). The method we used is cost-effective, and the recovery rates of ethanol and hexane ranged from 80−91% and 87−91% respectively. Overall, GAS and GASF are potential raw materials for lipids such as SM and PC extraction using the ethanol/hexane method. Comparatively, lipids extraction from the GAS is more effective and timesaving. Our finding would provide a way to utilize GAS and potentially control its invasion.

Both quiescent and proliferating cells circulate in the blood of the invasive apple snail Pomacea canaliculata

Gastropod hematopoiesis occurs at specialized tissues in some species, but the evidence also suggests that hemocyte generation is maybe widespread in the connective tissues or the blood system in others. In Ampullariidae (Caenogastropoda), both the kidney and the lung contain putative hematopoietic cells, which react to immune challenges. In the current study, we wanted to explore if hematopoiesis occurs in the blood of Pomacea canaliculata. Thus, we obtained circulating hemocytes from donor animals and tested their ability to proliferate in the blood of conspecific recipients. We tracked cell proliferation by labeling the donors' hemocytes with the fluorescent cell proliferation marker carboxyfluorescein diacetate succinimidyl ester (CFSE). Transferred CFSE-labeled hemocytes survived and proliferated into the recipients’ circulation for at least 17 days. We also determined the cell cycle status of circulating hemocytes by using the propidium iodide (PI) and acridine orange (AO) staining methods. Flow cytometry analyses showed that most PI-stained hemocytes were in the G1 phase (~96%), while a lower proportion of cells were through the G2/S-M transition (~4%). When we instead used AO-staining, we further distinguished a subpopulation of cells (~5%) of low size, complexity-granularity, and RNA content. We regarded this subpopulation as quiescent cells. In separate experimental sets, we complemented these findings by assessing in circulating hemocytes two evolutionary conserved features of quiescent, undifferentiated cells. First, we used JC-1 staining to determine the mitochondrial membrane potential (Ψm) of circulating hemocytes, which is expected to be low in quiescent cells. Most hemocytes (~87%) showed high aggregation of JC-1, which indicates a high Ψm. Besides that, a small hemocyte subpopulation (~11%) showed low aggregation of the dye, thus indicating a low Ψm. It is known that the transition from a quiescent to a proliferating state associates with an increase of the Ψm. The specificity of these changes was here controlled by membrane depolarization with the Ψm disruptor CCCP. Second, we stained hemocytes with Hoechst33342 dye to determine the efflux activity of ABC transporters, which participate in the multixenobiotic resistance system characteristic of undifferentiated cells. Most hemocytes (>99%) showed a low dye-efflux activity, but a small proportion of cells (0.06–0.12%) showed a high dye-efflux activity, which was significantly inhibited by 100 and 500 μM verapamil, and thus is indicative of an undifferentiated subpopulation of circulating hemocytes. Taken together, our results suggest that, among circulating hemocytes, there are cells with the ability to proliferate or to stay in a quiescent state and behave as progenitor cells later, either in the circulation or the hematopoietic tissues/organs.

Prey size and species preferences in the invasive blue crab, Callinectes sapidus: Potential effects in marine and freshwater ecosystems

The blue crab, Callinectes sapidus is an invasive species in the Mediterranean region. In Ebro Delta bays, it poses an important risk for the cultivation of Mediterranean mussel (Mytillus galloprovincialis) and Pacific oyster (Crassostrea gigas). Besides, the species thrives in the Ebro River hosting abundant populations of apple snail (Pomacea maculata) and Asian clam (Corbicula fluminea). Food-preference experiments were conducted to assess the effect of predator and prey sizes and prey type (M. galloprovincialis vs. C. gigas and P. maculata vs. C. fluminea) in predation patterns and its possible causes. Our results show that except for the Pacific oyster, which attains protection at sizes of 50–70 mm and was little consumed (0–16%), the other preys are readily predated, at variable rates (mussels: 38–96%; apple snail: 58–93%, and Asian clam: 67–100%), depending on predator and prey sizes. Juveniles and young blue crab adults showed greater consumption of small and medium mussels and a similar trend occurred with Asian clam. In contrast, large and medium apple snails were more heavily predated by adult blue crabs. Species comparisons also showed higher predation of mussels than oysters (71 vs. 8%), and of apple snail than Asian clam (99 vs. 72%). Once the shell barrier was removed, preference for mussels was still preserved, suggesting a nutritional preference. Our results point the need of fishing blue crab in marine areas to prevent losses in mussel production and highlight the potential control exerted over undesired invasive mollusk species.

Recent breeding range expansion of the endangered Snail Kite (Rostrhamus sociabilis) in Florida

The Snail Kite (Rostrhamus sociabilis plumbeus) is a wetland-dependent raptor that feeds primarily on aquatic apple snails (Pomacea sp.). In the United States, Snail Kites are endangered and breed exclusively in south and central Florida. Here we report that in 2018 and 2019, Snail Kites bred approximately 175 km north-northwest of the current northernmost breeding range. We combine historical and present information to interpret this new breeding event. Breeding occurred at Payne's Prairie Preserve State Park, an isolated wetland in Alachua County, Florida, USA, that was impacted in 2017 by high water levels due to Hurricane Irma and invasion of exotic apple snails (P. maculata). Counts of Snail Kites within the area rose steadily throughout 2018 and 2019 from 1 to a high of 84 individuals. We discovered 3 nests with eggs or chicks in 2018, and 75 nests in 2019, with nest success rates of 100% and 40%, respectively. To our knowledge, sightings within the county from 1968 to 2017 occurred on only 7 occasions, and nesting was observed only once, in 1919. From 2005 to 2019, the extent of Snail Kite breeding in counties across Florida was greater than previous years. However, long-term range expansion may depend on maintenance of wetland conditions as well as a number of factors including snail availability, drought, hydrology, predation, and temperature.

Microscopic Anatomy of the Gill and Lung of the Apple Snail Pomacea maculata, with Notes on the Volume of the Lung

The anatomy of the gills of aquatic gastropods has not been extensively studied, and in particular, there are few recent studies that contain ultramicroscopic images. Similarly, the literature on the anatomy of the lungs of air-breathing terrestrial snails is not voluminous. Apple snails of the genus Pomacea possess both a gill and a fully functional lung. The lung is used to breathe air and as a flotation device. This study reports on the anatomy of the gill, lung, and pneumostome of the invasive species Pomacea maculata. The gill has a structure similar to that reported in other gastropods. The gill is monopectinate and consists of numerous triangular filaments. Ciliary tracts populate the distal portions of the filaments. The filaments are primarily connective tissue, interspersed with abundant muscle bands and hemolymph sinuses. The lung is a large ovoid sac; the floor is attached to the foot of the snail and the roof of the lung underlies the mantle epithelium. The lung tissue layers consist of connective tissue and smooth muscle bundles, and hemolymph spaces are present in both the floor and roof. Cells that contain calcium granules are very abundant in the lung tissue. Patches of cilia adorn the epithelium adjacent to the central airspace. The pneumostome is a muscular structure and is heavily ciliated. The lung volume of a 50-g animal is about 6 mL. The results of this study add to the knowledge of the anatomy of respiratory organs in molluscs and show that the lung is a major site of storage of calcium.

Estivation in the Apple Snail Pomacea maculata: Mobilization of Calcium Granules in the Lung

The effect of long-term estivation on the abundance of calcium granules in the lung tissue of the apple snail Pomacea maculata Perry was studied. Electron-dispersive spectrophotometric analysis of the shell and the granular inclusions in the lung show that both structures are composed of calcium carbonate. The layers forming the shell are similar to those found in the shells of other gastropods. Calcium granules are extremely abundant in the tissues of the lung of P. maculata. The spherical granules consist of concentric layers of material inside calcium cells. There are three distinct populations of hemocytes in P. maculata hemolymph, two cell types with granulocytic morphology and one agranular type. Selective staining shows that hemocytes contain large amounts of calcium, implicating these cells in the transport of calcium carbonate from storage sites to other tissues. The pCO2 of the hemolymph increases in estivating gastropods, and it has been suggested that stores of solid calcium carbonate are mobilized to buffer the resulting acidity. Results of this study show that a large decrease in the abundance of calcium carbonate granules in the lung tissue occurs during estivation. In addition, there is evidence that a calcium binding protein is present in the hemocytes.