scholarly journals Husbandry of the Carnivorous Land Snail, Powelliphanta augusta (Gastropoda: Pulmonata: Rhytdidae)

2021 ◽  
Author(s):  
◽  
Thomas Edward Allan
Keyword(s):  
Weight Gain ◽  
Body Condition ◽  
Egg Production ◽  
Captive Breeding ◽  
Calcium Supplementation ◽  
Stocking Density ◽  
Land Snail ◽  
Captive Population ◽  
Mammalian Predators ◽  
In The Wild

<p>Key aspects of the captive husbandry of Powelliphanta augusta, a newly-described New Zealand land snail are investigated: how they should be managed and fed to provide individuals for release, and how a long-term captive population can be maintained as an insurance against extinction in the wild. This project arises from almost all members of this species having been brought into captivity due to their displacement in the wild by an opencast coalmine. Powelliphanta (F: Rhytididae) is a genus of endemic carnivorous snails, which includes 10 species, 27 subspecies and numerous undescribed taxa. As well as its diversity, Powelliphanta is renowned for the large size of its members (up to 90mm diameter) and their attractively-patterned shells. Most taxa are threatened due to habitat loss and predation by introduced mammalian predators. The study commences with a literature review to refine husbandry methods and to assess requirements for captive breeding of snails. From this review investigations are made into stocking densities, substrate, reproductive biology, body condition and growth of the P. augusta captive population. To determine an appropriate stocking density for P. augusta groups of six snails were kept at two densities; with either 720cm2, or 1440cm2 per group. Survival and weight gain were compared over 52 weeks. There was no difference in weight gain between treatments, but survival was significantly reduced at the highest density. The agent responsible for mortality was not identified, but previous studies on snails implicate disease. The effect of calcium supplementation on reproductive output was assessed by introducing limestone chip to the captive substrate of sphagnum moss. The experiment was aborted after eight months because of the apparently lethal effects of treatment. Egg production during this time was negligible, probably due to the lack of appropriate environmental cues. P. augusta showed evidence of size-specific fecundity, with a significant increase in clutch size with parental shell volume. Size-specific fecundity is predicted to cause size-assortative mating, but experiments determined that mate-choice is random with respect to shell size.Body condition was studied using the residuals from a regression of mass and size at time of capture. Condition in the wild showed strong seasonal variation, with a high in December and January. Body condition in captive snails remained stable, at a level equivalent to the peak of condition in the wild. The growth of captive snails was modeled using a Gompertz curve. Using a 30mm shell diameter as a reproductive indicator, snails hatching in captivity are predicted to reach maturity in approximately eight years. The study concludes by discussing the implications of the research for husbandry. Updates and expansions to the analyses are suggested, as well as methods for effectively monitoring the captive population.</p>

scholarly journals Husbandry of the Carnivorous Land Snail, Powelliphanta augusta (Gastropoda: Pulmonata: Rhytdidae)

2021 ◽  
Author(s):  
◽  
Thomas Edward Allan
Keyword(s):  
Weight Gain ◽  
Body Condition ◽  
Egg Production ◽  
Captive Breeding ◽  
Calcium Supplementation ◽  
Stocking Density ◽  
Land Snail ◽  
Captive Population ◽  
Mammalian Predators ◽  
In The Wild

<p>Key aspects of the captive husbandry of Powelliphanta augusta, a newly-described New Zealand land snail are investigated: how they should be managed and fed to provide individuals for release, and how a long-term captive population can be maintained as an insurance against extinction in the wild. This project arises from almost all members of this species having been brought into captivity due to their displacement in the wild by an opencast coalmine. Powelliphanta (F: Rhytididae) is a genus of endemic carnivorous snails, which includes 10 species, 27 subspecies and numerous undescribed taxa. As well as its diversity, Powelliphanta is renowned for the large size of its members (up to 90mm diameter) and their attractively-patterned shells. Most taxa are threatened due to habitat loss and predation by introduced mammalian predators. The study commences with a literature review to refine husbandry methods and to assess requirements for captive breeding of snails. From this review investigations are made into stocking densities, substrate, reproductive biology, body condition and growth of the P. augusta captive population. To determine an appropriate stocking density for P. augusta groups of six snails were kept at two densities; with either 720cm2, or 1440cm2 per group. Survival and weight gain were compared over 52 weeks. There was no difference in weight gain between treatments, but survival was significantly reduced at the highest density. The agent responsible for mortality was not identified, but previous studies on snails implicate disease. The effect of calcium supplementation on reproductive output was assessed by introducing limestone chip to the captive substrate of sphagnum moss. The experiment was aborted after eight months because of the apparently lethal effects of treatment. Egg production during this time was negligible, probably due to the lack of appropriate environmental cues. P. augusta showed evidence of size-specific fecundity, with a significant increase in clutch size with parental shell volume. Size-specific fecundity is predicted to cause size-assortative mating, but experiments determined that mate-choice is random with respect to shell size.Body condition was studied using the residuals from a regression of mass and size at time of capture. Condition in the wild showed strong seasonal variation, with a high in December and January. Body condition in captive snails remained stable, at a level equivalent to the peak of condition in the wild. The growth of captive snails was modeled using a Gompertz curve. Using a 30mm shell diameter as a reproductive indicator, snails hatching in captivity are predicted to reach maturity in approximately eight years. The study concludes by discussing the implications of the research for husbandry. Updates and expansions to the analyses are suggested, as well as methods for effectively monitoring the captive population.</p>

Sperm utilization in subadult and adult simultaneous hermaphrodite snails mating in the wild

2011 ◽  
Vol 89 (11) ◽  
pp. 1041-1049 ◽  
Author(s):  
Sandra Kupfernagel ◽  
Bruno Baur
Keyword(s):  
Sperm Competition ◽  
Egg Production ◽  
Shell Growth ◽  
Land Snail ◽  
Snail Species ◽  
Simultaneous Hermaphrodite ◽  
Young Females ◽  
Short Period ◽  
In The Wild ◽  
Previous Mating

In species with multiple mating and long-term sperm storage, males are expected to show a preference for mating with virgin and young females to reduce the risk of sperm competition. In various simultaneous hermaphrodite land snail species, sperm production precedes egg production by 2–4 weeks, resulting in a short period of protandric hermaphroditism before shell growth is completed. In a natural population, we collected copulating pairs of the simultaneous hermaphrodite land snail Arianta arbustorum (L., 1758) consisting either of two adults, of two subadults, or of one adult and one subadult snail, and determined the paternity of their hatchlings that emerged from subsequently deposited eggs. Adult snails used sperm received from subadult mating partners for egg fertilization in the same frequency as sperm from adults, indicating that subadult and adult snails do not differ in male function. Furthermore, an unfinished shell is not a reliable indicator for virginity, because 35% of the subadult individuals had already sperm stored from previous mating(s). Compared with adults, young individuals exhibited a lower risk of sperm competition, indicated by a higher last mate sperm precedence. However, subadult snails produced fewer eggs than adult snails, counteracting the evolutionary advantage of preferring a young partner with low sperm competition risk.

scholarly journals Cost of autotomy drives ontogenetic switching of anti-predator mechanisms under developmental constraints in a land snail

2012 ◽  
Vol 279 (1748) ◽  
pp. 4811-4816 ◽  
Author(s):  
Masaki Hoso
Keyword(s):  
High Efficiency ◽  
Shell Growth ◽  
Land Snail ◽  
Life History Strategies ◽  
Body Parts ◽  
Developmental Constraint ◽  
Developmental Constraints ◽  
Evolution Of Life ◽  
Snake Range ◽  
In The Wild

Autotomy of body parts offers various prey animals immediate benefits of survival in compensation for considerable costs. I found that a land snail Satsuma caliginosa of populations coexisting with a snail-eating snake Pareas iwasakii survived the snake predation by autotomizing its foot, whereas those out of the snake range rarely survived. Regeneration of a lost foot completed in a few weeks but imposed a delay of shell growth. Imprints of autotomy were found in greater than 10 per cent of S. caliginosa in the snake range but in only less than 1 per cent out of it, simultaneously demonstrating intense predation by the snakes and high efficiency of autotomy for surviving snake predation in the wild. However, in experiments, mature S. caliginosa performed autotomy less frequently. Instead of the costly autotomy, they can use defensive denticles on the inside of their shell apertures. Owing to the constraints from the additive growth of shells, most pulmonate snails can produce these denticles only when they have fully grown up. Thus, this developmental constraint limits the availability of the modified aperture, resulting in ontogenetic switching of the alternative defences. This study illustrates how costs of adaptation operate in the evolution of life-history strategies under developmental constraints

scholarly journals Monitoring invasive mammalian predator populations sharing habitat with the Critically Endangered Puerto Rican parrot Amazona vittata

Oryx ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Richard Engeman ◽  
Desley Whisson ◽  
Jessica Quinn ◽  
Felipe Cano ◽  
Pedro Quiñones ◽  
...  
Keyword(s):  
Puerto Rican ◽  
Habitat Type ◽  
Critically Endangered ◽  
Mammal Species ◽  
Forest Sites ◽  
The World ◽  
Mammalian Predators ◽  
In The Wild ◽  
Amazona Vittata ◽  
Black Rats

Critically Endangered Puerto Rican parrots Amazona vittata are one of the rarest birds in the world. Several exotic mammal species capable of preying on Puerto Rican parrots cohabit the Caribbean National Forest with the only wild population of these parrots. We used tracking plates, monitoring blocks and trapping to index black rats, small Indian mongooses and feral cats in parrot habitat and in public-use areas in the same habitat type. We had high trap success for black rats at all sites (42% of all sites combined), among the highest reported in the world. Rat response to monitoring (nontoxic bait) blocks was universally high, regardless of ground or tree placement. Mongooses were present at all sites, with a greater proportion of plates tracked within the forest than at public-use sites. Cats were present at all forest sites and one of the public-use sites. Presence of the three species did not appear to be linked to human disturbance. Because only 30–40 Puerto Rican parrots survive in the wild, with as few as three pairs nesting in 2002, we concluded that the abundance and pervasiveness of exotic mammalian predators poses a greater threat to the parrots than has been generally acknowledged. This is evidenced by mammalian predation during recent parrot breeding seasons, including six fledglings taken by mongooses and one nest failure from rats during 2000–2003.

Assisted colonisation trial of the eastern barred bandicoot (Perameles gunnii) to a fox-free island

2017 ◽  
Vol 44 (7) ◽  
pp. 484 ◽  
Author(s):  
Rebecca Groenewegen ◽  
Dan Harley ◽  
Richard Hill ◽  
Graeme Coulson
Keyword(s):  
Habitat Use ◽  
Body Condition ◽  
Red Fox ◽  
Suitable Habitat ◽  
Viable Option ◽  
Predator Exclusion ◽  
In The Wild ◽  
Radio Transmitters ◽  
Release Group ◽  
Small Sites

Context Assisted colonisation has the potential to protect species from intractable threats within their historical ranges. The Australian mainland subspecies of the eastern barred bandicoot (Perameles gunnii) is extinct in the wild, with surviving populations restricted to small sites protected by predator–barrier fences. PVA modelling shows that a self-sustaining bandicoot population would require an area free of the introduced red fox (Vulpes vulpes) of at least 2500ha. French Island is outside the historic range of the species, but is fox-free and contains around 9000ha of potentially suitable habitat. Aims This study will assess the suitability of French Island as a potential site for a self-sustaining eastern barred bandicoot population by conducting a 1-year assisted colonisation trial to assess habitat use, body condition and survival. Methods Between July and September 2012, 18 adult bandicoots were released. We radio-tracked bandicoots using intraperitoneal radio-transmitters for up to 122 days and trapped fortnightly. Key results The release group met the three measures of success: (1) appropriate habitat use; (2) recovery of post-release bodyweight; and (3) founder survival exceeding 100 days. Habitat use and body condition throughout the trial reflected that of mainland populations, and seven bandicoots survived longer than 100 days. Mortality was greatest in the first month, with veterinary investigations confirming two deaths due to cat predation, two deaths from toxoplasmosis and one unknown cause of death. Bandicoots that survived longer than 100 days occupied higher, drier ground than those that did not. Toxoplasmosis cases were associated with lower topographic position on the site. Conclusions Our results suggest that French Island provides suitable habitat for the establishment of a population of eastern barred bandicoots. On French Island, toxoplasmosis was identified as an important source of mortality in addition to cat predation, and warrants further investigation. Implications Given the costs and challenges of predator control and the maintenance of predator exclusion fences, assisted colonisation to one or more fox-free islands remains the most viable option to establish self-sustaining bandicoot populations. Our results highlight the value in conducting trial releases ahead of major translocations.

Effects of adult stocking density on egg production and viability in cultures of the calanoid copepod Acartia tonsa (Dana)

2007 ◽  
Vol 38 (7) ◽  
pp. 764-772 ◽  
Author(s):  
Per M Jepsen ◽  
Nikolaj Andersen ◽  
Thue Holm ◽  
Anders T Jørgensen ◽  
Jonas K Højgaard ◽  
...  
Keyword(s):  
Egg Production ◽  
Calanoid Copepod ◽  
Stocking Density ◽  
Acartia Tonsa

Behavioural aspects of microhabitat segregation of different age stages in the wetland land snail Vertigo moulinsiana (Eupulmonata: Vertiginidae) in the laboratory

2020 ◽  
Vol 86 (3) ◽  
pp. 228-232
Author(s):  
Zofia Książkiewicz-Parulska
Keyword(s):  
High Temperature ◽  
Land Snail ◽  
Snail Species ◽  
High Humidity ◽  
Short Period ◽  
Temperature And Humidity ◽  
In The Wild ◽  
Different Response ◽  
Behavioural Aspects ◽  
Microhabitat Segregation

ABSTRACT This laboratory study investigated behavioural differences between adults and juveniles of the wetland land snail species Vertigo moulinsiana with respect to temperature and humidity. Juveniles of V. moulinsiana, for example, tend to remain within the shaded, humid and cool layer of the litter, while adults usually climb above wet vegetation to a height of over 2 m. Adults are thus exposed to greater variation in temperature and humidity than juveniles. My experiments showed that adults of V. moulinsiana remain active longer than juveniles when subject to high temperature (36 °C) and low relative humidity (RH 30%). Conversely, juveniles stay active longer than adults in high humidity (22 °C, RH 100%). A short period of starvation lengthened the time needed for the juveniles to become active after dormancy, possibly indicating a different response between adults and juveniles to lack of nutritional reserves. These behavioural differences to food availability and the risk of water loss correspond to the microhabitat differences observed between adults and juveniles in the wild.

scholarly journals Dietary Germinated Paddy Rice and Stocking Density Affect Egg Performance, Serum Biochemical Properties, and Proteomic and Transcriptomic Response of Laying Hens Exposed to Chronic Heat Stress

Proteomes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 48
Author(s):  
Tossaporn Incharoen ◽  
Sittiruk Roytrakul ◽  
Wirot Likittrakulwong
Keyword(s):  
Heat Stress ◽  
Egg Production ◽  
Laying Hens ◽  
Protein Profile ◽  
Stocking Density ◽  
Biochemical Properties ◽  
Paddy Rice ◽  
Egg Mass ◽  
Serum Samples ◽  
Transcriptomic Response

Germinated paddy rice (GPR) could be a good alternative feed source for poultry with stocking density and heat stress problems. A total of 72 Hy-line Brown laying hens raised under low (LSD, 0.12 m2/bird) and high stocking densities (HSD, 0.06 m2/bird) were investigated. Three dietary GPR levels (0, 74 and 148 g/kg) were used. It was found that average daily feed intake, hen-day egg production, and egg mass significantly decreased in the HSD group. The levels of serum glucose (GLU), phosphorous (P), corticosterone (CORT), total Ig, lysozyme (LZY), and superoxide dismutase activities (SOD) in the HSD group were higher than those in the LSD group. Dietary GPR significantly affected GLU, P, alternative complement haemolytic 50 (ACH50), total Ig, and LZY. Moreover, CORT level significantly decreased in 74 and 148 g/kg dietary GPR groups, whereas SOD significantly increased only in the 148 g/kg dietary GPR group. Serum samples were analyzed using liquid chromatography-tandem mass spectrometry, and 8607 proteins were identified. Proteome analysis revealed 19 proteins which were enriched in different stocking densities and dietary GPR levels. Quantitative real-time reverse transcription-PCR technique was successfully used to verify the differentiated abundant protein profile changes. The proteins identified in this study could serve as appropriate biomarkers.

scholarly journals Crossbred Local Chickens from East Nusa Tenggara Province Indonesia Under Semi Intensive Management System

2021 ◽  
Vol 748 (1) ◽  
pp. 012003
Author(s):  
N.G.A Mulyantini S.S ◽  
Ulrikus R Lole
Keyword(s):  
Weight Gain ◽  
Artificial Insemination ◽  
Management System ◽  
Egg Production ◽  
Abdominal Fat ◽  
Production Performance ◽  
The Other ◽  
Intensive Management ◽  
Commercial Grower ◽  
Local Chickens

Abstract The objective of this study was to compare the performance of four-breed combination under semiintensive management system. The experiment used 160 females and 40 males chickens as parents. Artificial insemination was performed to produce the experimental chicken of the four breed combinations (1. Sabu x Sabu, 2. Sabu x Semau, 3. Sabu x KUB, 4. Semau x KUB). The chickens were fed with chick starter crumb sad libitum from day old to 4 weeks of age. From 4-8 weeks of age, chickens were allowed to scavenge during the day, and also given commercial grower pellets + rice bran + corn (5:4:1). Combination of Sabu x KUBfrom 4-8 weeks of age were significantly heavier (P < 0.05) than the other combination breeds. Feed intake in the Sabu x KUB group was the lowest, and their weight gain was the highest among the others group(P < 0.05). The combination Sabu x KUB also had the highest egg production, and hatchability. However, the percentage of abdominal fat of Sabu x KUB were higher than others groups. In conclusion, combination Sabu x KUB had the best growth performance and egg production performance, but not for the percentage of abdominal fat.

scholarly journals Is maternal thyroid hormone deposition subject to a trade-off between self and egg because of iodine? An experimental study in rock pigeon

2021 ◽  
Author(s):  
Tom Sarraude ◽  
Bin-Yan Hsu ◽  
Suvi Ruuskanen ◽  
Ton Groothuis
Keyword(s):  
Egg Production ◽  
Developmental Stages ◽  
Columba Livia ◽  
Captive Population ◽  
Restricted Diet ◽  
Trade Off ◽  
Metabolic Hormones ◽  
Hormone Exposure ◽  
Maternal Thyroid ◽  
Early Developmental

Maternal hormones constitute a key signalling pathway for mothers to shape offspring phenotype and fitness. Thyroid hormones (THs; triiodothyronine, T3 and thyroxine, T4) are metabolic hormones known to play crucial roles in embryonic development and survival in all vertebrates. During early developmental stages, embryos exclusively rely on the exposure to maternal THs, and maternal hypothyroidism can cause severe embryonic maldevelopment. The TH molecule includes iodine, an element that cannot be synthesised by the organism. Therefore, TH production may become costly when environmental iodine availability is low. This may yield a trade-off for breeding females between allocating the hormones to self or to their eggs, potentially to the extent that it even influences the number of laid eggs. In this study, we investigated whether low dietary iodine may limit TH production and transfer to the eggs in a captive population of Rock pigeons (Columba livia). We provided breeding females with an iodine-restricted (I- diet) or iodine-supplemented diet (I+ diet) and measured the resulting circulating and yolk iodine and TH concentrations and the number of eggs laid. Our iodine-restricted diet successfully decreased both circulating and yolk iodine concentrations compared to the supplemented diet, but not circulating or yolk THs. This indicates that mothers may not be able to independently regulate hormone exposure for self and their embryos. However, egg production was clearly reduced in the I- group, with fewer females laying eggs. This result shows that restricted availability of iodine does induce a cost in terms of egg production. Whether females reduced egg production to preserve THs for themselves or to prevent embryos from exposure to low iodine and/or THs is as yet unclear.

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