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Steven G. Platt - One of the best experts on this subject based on the ideXlab platform.
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A recent population assessment of the American Crocodile (Crocodylus acutus) in Turneffe Atoll, Belize
2015Co-Authors: Steven G. Platt, Thomas R Rainwater, Stephen NicholsAbstract:ABSTRACT — We investigated the status of the American Crocodile (Crocodylus acutus) in Turneffe Atoll, Belize during 2002 and 2004. A combination of spotlight surveys and counts of recently hatched nests were used to census the Crocodile population. A total of 49 Crocodiles were observed along 40.1 km of survey route (1.2 Crocodiles/km) during spotlight surveys in 2002. This encounter rate was not significantly different from that reported in surveys conducted during the mid-1990's. Eight and 20 recently hatched nests were found in 2002 and 2004, respectively. The number of nests found in 2004 exceeds the previously reported maximum count of 15, suggesting that recruitment of breeding females into the population may be occurring. Crocodile nests were found at four sites in Tumefied Atoll. The most significant nesting beach in Belize is located on Northern Cay and currently threatened by a proposed tourist development. Failure to protect this beach could have potentially devastating consequences for C. acutus in Belize. HE American Crocodile (Crocodylus acutus) has one of the most extensive distributions of any crocodilian in the New World, occurring along the Atlantic and Pacific Coasts of Mexico, and Central and South America as well as th
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ocular disease in american Crocodiles crocodylus acutus in costa rica
Journal of Wildlife Diseases, 2011Co-Authors: Thomas R Rainwater, Steven G. Platt, Nicholas J Millichamp, Luz Denia Barrantes Barrantes, Brady Barr, Juan Rafael Bolanos Montero, Mike T Abel, George P. Cobb, Todd A AndersonAbstract:Beginning in early 2006, an ocular disease of unknown etiology was routinely observed in American Crocodiles (Crocodylus acutus) inhabiting the highly polluted Tarcoles River in west-central Costa Rica. We examined the nature and incidence of ocular disease in Tarcoles Crocodiles and assessed the possible association between the disease and accumulation of chemical pollutants in diseased individuals. During 12–15 September and 12–13 December 2007, Crocodiles were captured and examined for ocular disease and sampled to determine environmental contaminant accumulation. Three of 11 (27.3%) Crocodiles captured (all males) exhibited unilateral ocular disease, primarily characterized by corneal opacity and scarring, anterior synechia, and phthisis bulbi. Multiple pollutants were detected in Crocodile caudal scutes (organochlorine pesticides [OCPs] and metals), Crocodile blood (OCPs), and sediments (OCPs and metals) from the Tarcoles, but no associations were found between contaminant accumulation and the incide...
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Possible decline of an American Crocodile (Crocodylus acutus) population on Turneffe Atoll, Belize
The Herpetological Bulletin, 2009Co-Authors: Thomas R Rainwater, Steven G. PlattAbstract:Surveys of the American Crocodile (Crocodylus acutus) in Turneffe Atoll, Belize over the last decade have suggested that populations remain stable but are increasingly threatened by habitat loss, particularly human development of critical nesting beaches. In May, June and July 2008 we used a combination of spotlight surveys and nest counts to evaluate the current status of C. acutus populations in Turneffe Atoll. A total of 23 C. acutus was observed along 46.6 Km of survey route (0.49 Crocodiles/Km) during spotlight surveys in May, and 8 Crocodiles were observed along 45.3 Km of survey route (0.18 Crocodiles/Km) during late June-early July, yielding an overall 2008 encounter rate of 0.34 Crocodiles/Km. This encounter rate was significantly lower than that reported for surveys conducted in 2002. Two recently hatched nests, both on the same beach, were found during nest counts; no nests were found on other beaches known to have routinely yielded nests in the past. The number of nests found in this study is 4- to 10-fold lower than those reported from 1994 to 2004, suggesting a reduction in breeding females in the Turneffe Atoll Crocodile population. Development of two important nesting beaches on Blackbird Cay since 2004 has likely rendered these habitats unsuitable for future nesting. The combination of low Crocodile encounter rates, reduced nesting activity and human alteration of known nesting beaches observed in this study suggests a possible decline in the C. acutus population in Turneffe Atoll. Continued population assessments will be essential in monitoring the status of C. acutus in Turneffe Atoll, and immediate management and conservation efforts should be made to protect beaches on Blackbird, Calabash, and Northern Cays to provide critical nesting habitat for Crocodiles.
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consumption of large mammals by crocodylus moreletii field observations of necrophagy and interspecific kleptoparasitism
Southwestern Naturalist, 2007Co-Authors: Steven G. Platt, Thomas R Rainwater, Todd A Anderson, Scott Snider, Anthony Garel, Scott T McmurryAbstract:Abstract The consumption of large (>15 kg) mammals by Morelet's Crocodile (Crocodylus moreletii) is poorly documented. We present field observations of necrophagy and interspecific kleptoparasitism (defined as the stealing of food from an individual by another individual) involving the consumption of domestic cattle (Bos taurus) and Baird's tapir (Tapirus bairdii) carcasses, respectively, by Morelet's Crocodile in Belize. Our single observation of kleptoparasitism occurred when an adult Crocodile fed upon and attempted to hijack a tapir killed by a jaguar (Panthera onca). Crocodiles gained access to the interior of carcasses by tearing through the abdominal wall (tapir) or expanding an opening made by feeding vultures (cattle); feeding then progressed to the limbs, neck, and head. Crocodiles quickly located and congregated at cattle carcasses, possibly attracted by large flocks of feeding vultures. Feeding aggregations were composed solely of adult Crocodiles; juveniles and subadults were probably exclude...
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A recent population assessment of the American Crocodile (Crocodylus acutus) in Turneffe Atoll, Belize
The Herpetological Bulletin, 2004Co-Authors: Steven G. Platt, Thomas R Rainwater, Stephen NicholsAbstract:We investigated the status of the American Crocodile (Crocodylus acutus) in Turneffe Atoll, Belize during 2002 and 2004. A combination of spotlight surveys and counts of recently hatched nests were used to census the Crocodile population. A total of 49 Crocodiles were observed along 40.1 km of survey route (1.2 Crocodiles/km) during spotlight surveys in 2002. This encounter rate was not significantly different from that reported in surveys conducted during the mid-1990's. Eight and 20 recently hatched nests were found in 2002 and 2004, respectively. The number of nests found in 2004 exceeds the previously reported maximum count of 15, suggesting that recruitment of breeding females into the population may be occurring. Crocodile nests were found at four sites in Tumefied Atoll. The most significant nesting beach in Belize is located on Northern Cay and currently threatened by a proposed tourist development. Failure to protect this beach could have potentially devastating consequences for C. acutus in Belize.
Edoardo Pozio - One of the best experts on this subject based on the ideXlab platform.
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Development of an ELISA to detect the humoral immune response to Trichinella zimbabwensis in Nile Crocodiles (Crocodylus niloticus).
Veterinary parasitology, 2013Co-Authors: Alessandra Ludovisi, Louis Jacobus La Grange, Maria Angeles Gómez Morales, Edoardo PozioAbstract:Crocodiles are known reservoir hosts of Trichinella papuae and Trichinella zimbabwensis, two zoonotic parasites that also infect mammals. Since commercial Crocodile farming represents a key source of income in several countries, it is important to monitor this nematode infection in both farmed Crocodiles and in breeding stocks which are frequently introduced from the wild. For this purpose, an indirect ELISA was developed to detect the anti-Trichinella immune response in Crocodile sera. New Zealand rabbits were immunized with pooled sera from non-infected farmed Crocodiles in the presence of Freund's complete adjuvant. The anti-Crocodile serum was then conjugated with horseradish peroxidase. Serum samples from four Nile Crocodiles (Crocodylus niloticus) experimentally infected with T. zimbabwensis and from four uninfected Crocodiles were used to set up the ELISA. The larval burden per gram of muscle tissue was determined by muscle biopsy. The test was performed on serum samples from an additional 15 experimentally infected Crocodiles as well as eight wild Nile Crocodiles. Among the 19 experimentally infected Crocodiles, seroconversion was observed in 11 animals. The highest antibody response was observed six weeks post infection (p.i.), but in most of these animals, antibodies were not detectable after six weeks p.i. even though live larvae were present in the muscles up to six months p.i.
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trichinella papuae in saltwater Crocodiles crocodylus porosus of papua new guinea
Emerging Infectious Diseases, 2004Co-Authors: Edoardo Pozio, Ifor L Owen, Gianluca Marucci, Giuseppe La RosaAbstract:To the Editor: Until 1995, reptiles were not known to be hosts of Trichinella; however, in that year Trichinella was detected in 40% of farm-raised Crocodiles (Crocodylus niloticus) in Zimbabwe. These Crocodiles were infected with a new species, T. zimbabwensis, which was experimentally infective in mammals, including primates (1). The infection of reptiles with Trichinella species that are potentially infective for humans has become more important since demand for the meat of Crocodiles, caimans, and alligators has increased in many areas of the world. This trend has resulted in the development of national breeding programs in more than 30 countries in North, Central, and South America; Africa; Asia; and Australia (2), which generated an income of approximately $60 million in 1998 (3). In 1999 in Papua New Guinea, wild and domestic pigs infected with a new species, T. papuae, were found (4,5); this new species was capable of completing its life cycle in reptiles that were infected experimentally (6). Trichinella infection has also been found in farm-raised saltwater Crocodiles (C. porosus) in Papua New Guinea, where a national program for Crocodile meat and skin products exists. Papua New Guinea has one Crocodile breeding farm that processes approximately 6,000 animals per year. Following the discovery of Trichinella-infected Crocodiles in Zimbabwe, the Australian government requested that Papua New Guinea conduct Trichinella testing on the Crocodile meat exported to Australia. Muscle samples from Crocodiles were digested by pepsin and HCl solution according to the standard technique (7). When available, approximately 100 larvae from each infected Crocodile were given by mouth to laboratory rats, and 10–20 larvae were stored in 90% ethyl alcohol for molecular identification. Multiplex polymerase chain reaction (PCR) was used to characterize the larvae, according to a published protocol (8). The primer set oTsr1 and oTsr4 was used to amplify the expansion segment V of the large subunit ribosomal RNA (9). The larvae of all Trichinella reference strains were used as controls. PCR products were gel-purified and directly sequenced by using the same primers as those used for PCR amplification. All sequences were aligned by using the Clustal W program from OMIGA 2.0 (Accelrys, San Diego, CA). Final alignment of the expansion segment V sequences was performed manually so microsatellites could be compared. Muscle samples from 118 saltwater Crocodiles (46 farm-born, 71 wild-born and farm-raised, and 1 killed in the wild near the Bensbach River) were tested. All samples from the farm-born Crocodiles were negative for Trichinella. Of the samples from the 72 wild-born Crocodiles (including the 1 killed in the wild), 16 (22.2%) were positive for Trichinella larvae, with an average of 7 larvae/g in the biceps. All of the infected Crocodiles originated in the Kikori area (Figure). The prevalence of Trichinella infection in Crocodiles from this area was 32.0% (16/50). Samples from the remaining 21 wild-born and farm-raised Crocodiles, and the 1 killed in the wild, were negative for Trichinella. These Crocodiles originated in nine different locations (Figure). Figure Papua New Guinea showing the areas of origin of the 72 wild-born saltwater Crocodiles (Crocodylus porosus): 1 each from Baimuru, Angoram, Timbunke, Kimbe, Bensbach River, and Buka; 2 from Labu; 7 from Wewak; 7 from Popondetta; and 50 from Kikori. PCR analysis showed that the parasites belonged to T. papuae. However, the Crocodile isolates differed from the reference strain of this species by the deletion of a TG dinucleotide and by a single base mutation (G vs. A) in the expansion segment V sequence. Testing for Trichinella in Crocodile meat has been conducted in Zimbabwe and Papua New Guinea only, and infected Crocodiles have been found in both countries. Crocodiles in other parts of the world are also likely to be infected. Since both T. zimbabwensis and T. papuae infection can develop in reptiles and mammals, eating Crocodile meat is a risk. In one region of Papua New Guinea, a high percentage of the local human population had anti-Trichinella antibodies (10). Moreover, the risk for human infection may be rising, given the increased marketing of meat from Crocodiles, caimans, and alligators in many parts of the world (2). The meat of other carnivorous reptiles, although consumed in very few areas, may also represent a source of infection, as suggested by the large number of larvae of both T. papuae and T. zimbabwensis in the muscles of experimentally infected monitor lizards (6). The presence of a TG dinucleotide in the expansion segment V sequence could be a useful marker for tracing the region of origin of infected meat. The infected Crocodiles, all of which were born in the wild, likely acquired infection before they arrived on the farm, since none of the farm-born Crocodiles was infected. In Zimbabwe, the source of infection was the Trichinella-infected Crocodile meat that had been fed to the other Crocodiles; the farm in Papua New Guinea does not engage in this practice, which would explain why none of its farm-born animals was infected. This study shows the importance of implementing measures to prevent the spread of Trichinella infection. For instance, since both T. papuae and T. zimbabwensis can be easily transmitted from Crocodiles to mammals, the discarded parts of Crocodiles should be properly destroyed to avoid transmission to synanthropic animals, and the waste products should not be fed to domestic animals, unless the products are frozen or cooked before use. Crocodile-breeding farms should adopt the artificial digestion method used in many countries to screen pigs for Trichinella infection (7). Freezing Crocodile meat, as practiced in Papua New Guinea, can also prevent infection because freezing destroys T. papuae and T. zimbabwensis larvae in muscles (1,4). By contrast, salting, drying, smoking, or preserving Crocodile meat in brine will not destroy trichinellae; these curing methods are not standardized, and the survival of Trichinella larvae can depend on factors such as salt concentration, moisture, and temperature (7). Similarly, Crocodile meat is frequently vacuum sealed, and the Trichinella larvae can retain their infectivity for several months in this environment (7).
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trichinella papuae in saltwater Crocodiles crocodylus porosus of papua new guinea
Emerging Infectious Diseases, 2004Co-Authors: Edoardo Pozio, Ifor L Owen, Gianluca Marucci, Giuseppe La RosaAbstract:To the Editor: Until 1995, reptiles were not known to be hosts of Trichinella; however, in that year Trichinella was detected in 40% of farm-raised Crocodiles (Crocodylus niloticus) in Zimbabwe. These Crocodiles were infected with a new species, T. zimbabwensis, which was experimentally infective in mammals, including primates (1). The infection of reptiles with Trichinella species that are potentially infective for humans has become more important since demand for the meat of Crocodiles, caimans, and alligators has increased in many areas of the world. This trend has resulted in the development of national breeding programs in more than 30 countries in North, Central, and South America; Africa; Asia; and Australia (2), which generated an income of approximately $60 million in 1998 (3). In 1999 in Papua New Guinea, wild and domestic pigs infected with a new species, T. papuae, were found (4,5); this new species was capable of completing its life cycle in reptiles that were infected experimentally (6). Trichinella infection has also been found in farm-raised saltwater Crocodiles (C. porosus) in Papua New Guinea, where a national program for Crocodile meat and skin products exists. Papua New Guinea has one Crocodile breeding farm that processes approximately 6,000 animals per year. Following the discovery of Trichinella-infected Crocodiles in Zimbabwe, the Australian government requested that Papua New Guinea conduct Trichinella testing on the Crocodile meat exported to Australia. Muscle samples from Crocodiles were digested by pepsin and HCl solution according to the standard technique (7). When available, approximately 100 larvae from each infected Crocodile were given by mouth to laboratory rats, and 10–20 larvae were stored in 90% ethyl alcohol for molecular identification. Multiplex polymerase chain reaction (PCR) was used to characterize the larvae, according to a published protocol (8). The primer set oTsr1 and oTsr4 was used to amplify the expansion segment V of the large subunit ribosomal RNA (9). The larvae of all Trichinella reference strains were used as controls. PCR products were gel-purified and directly sequenced by using the same primers as those used for PCR amplification. All sequences were aligned by using the Clustal W program from OMIGA 2.0 (Accelrys, San Diego, CA). Final alignment of the expansion segment V sequences was performed manually so microsatellites could be compared. Muscle samples from 118 saltwater Crocodiles (46 farm-born, 71 wild-born and farm-raised, and 1 killed in the wild near the Bensbach River) were tested. All samples from the farm-born Crocodiles were negative for Trichinella. Of the samples from the 72 wild-born Crocodiles (including the 1 killed in the wild), 16 (22.2%) were positive for Trichinella larvae, with an average of 7 larvae/g in the biceps. All of the infected Crocodiles originated in the Kikori area (Figure). The prevalence of Trichinella infection in Crocodiles from this area was 32.0% (16/50). Samples from the remaining 21 wild-born and farm-raised Crocodiles, and the 1 killed in the wild, were negative for Trichinella. These Crocodiles originated in nine different locations (Figure). Figure Papua New Guinea showing the areas of origin of the 72 wild-born saltwater Crocodiles (Crocodylus porosus): 1 each from Baimuru, Angoram, Timbunke, Kimbe, Bensbach River, and Buka; 2 from Labu; 7 from Wewak; 7 from Popondetta; and 50 from Kikori. PCR analysis showed that the parasites belonged to T. papuae. However, the Crocodile isolates differed from the reference strain of this species by the deletion of a TG dinucleotide and by a single base mutation (G vs. A) in the expansion segment V sequence. Testing for Trichinella in Crocodile meat has been conducted in Zimbabwe and Papua New Guinea only, and infected Crocodiles have been found in both countries. Crocodiles in other parts of the world are also likely to be infected. Since both T. zimbabwensis and T. papuae infection can develop in reptiles and mammals, eating Crocodile meat is a risk. In one region of Papua New Guinea, a high percentage of the local human population had anti-Trichinella antibodies (10). Moreover, the risk for human infection may be rising, given the increased marketing of meat from Crocodiles, caimans, and alligators in many parts of the world (2). The meat of other carnivorous reptiles, although consumed in very few areas, may also represent a source of infection, as suggested by the large number of larvae of both T. papuae and T. zimbabwensis in the muscles of experimentally infected monitor lizards (6). The presence of a TG dinucleotide in the expansion segment V sequence could be a useful marker for tracing the region of origin of infected meat. The infected Crocodiles, all of which were born in the wild, likely acquired infection before they arrived on the farm, since none of the farm-born Crocodiles was infected. In Zimbabwe, the source of infection was the Trichinella-infected Crocodile meat that had been fed to the other Crocodiles; the farm in Papua New Guinea does not engage in this practice, which would explain why none of its farm-born animals was infected. This study shows the importance of implementing measures to prevent the spread of Trichinella infection. For instance, since both T. papuae and T. zimbabwensis can be easily transmitted from Crocodiles to mammals, the discarded parts of Crocodiles should be properly destroyed to avoid transmission to synanthropic animals, and the waste products should not be fed to domestic animals, unless the products are frozen or cooked before use. Crocodile-breeding farms should adopt the artificial digestion method used in many countries to screen pigs for Trichinella infection (7). Freezing Crocodile meat, as practiced in Papua New Guinea, can also prevent infection because freezing destroys T. papuae and T. zimbabwensis larvae in muscles (1,4). By contrast, salting, drying, smoking, or preserving Crocodile meat in brine will not destroy trichinellae; these curing methods are not standardized, and the survival of Trichinella larvae can depend on factors such as salt concentration, moisture, and temperature (7). Similarly, Crocodile meat is frequently vacuum sealed, and the Trichinella larvae can retain their infectivity for several months in this environment (7).
Colleen T. Downs - One of the best experts on this subject based on the ideXlab platform.
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use of an unmanned aerial vehicle drone to survey nile Crocodile populations a case study at lake nyamithi ndumo game reserve south africa
Biological Conservation, 2018Co-Authors: Mohamed A Ezat, Camille J Fritsch, Colleen T. DownsAbstract:Abstract Observer bias and inexperience are challenging aspects of Crocodile survey methods for determining population numbers and structure. Aerial surveys with either a helicopter or a fixed winged aircraft are generally preferred methods to ground surveys; however, the high cost of the former is a limiting factor. Recently unmanned aerial vehicles (UAVs) or drones have been proposed for surveys because of their potential of improving over traditional techniques of wildlife monitoring and as they have relatively lower costs. We investigated of the suitability of a UAV to determine numbers and structure of the Nile Crocodile, Crocodylus niloticus, population during winter at Lake Nyamithi, Ndumo Game Reserve in South Africa. We used the UAV for eight flights covering ~132 ha. We also conducted a diurnal ground survey of Crocodiles for comparison. Using the UAV, 287 Crocodiles were identified and body length measured accurately for size class allocation whereas only 211 Crocodiles were counted in the diurnal ground survey. Consequently, the UAV aerial survey recorded 26% more Crocodiles. The potential of using UAVs to estimate Crocodile population size and measure the total length (TL) of individuals accurately and precisely at a relatively low cost should improve management actions, enable monitoring of the Crocodile populations annually and importantly avoid observer bias. Implications of this may facilitate improved crocodilian survey techniques.
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Status of the Nile Crocodile Population in Pongolapoort Dam After River Impoundment
African Zoology, 2017Co-Authors: Garreth Champion, Colleen T. DownsAbstract:The major Nile Crocodile Crocodylus niloticus populations in South Africa are threatened by pollution, habitat alteration/destruction, and poaching. This has highlighted the importance of other minor populations. The Phongola River Nile Crocodile population was previously considered as unsubstantial. Consequently, we investigated the Nile Crocodile population numbers and status and the effects of the impoundment of the Phongola River on this. In 2009–2010 we determined a minimum population number of 281 Nile Crocodiles in Pongolapoort Dam using a combination of survey methods. The population structure was identified as having a minimum of 116 (41.3%) juveniles ( 2.5 m total length). At the commencement of the breeding season in August, Crocodiles congregated at a major basking site where the main tributary entered the dam. Three major nesting areas were identified, two of which were located on the river inlet to th...
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Movement and Home Range of Nile Crocodiles in Ndumo Game Reserve, South Africa
Koedoe, 2015Co-Authors: Peter M Calverley, Colleen T. DownsAbstract:The study of movement patterns and home range is fundamental in understanding the spatial requirements of animals and is important in generating information for the conservation and management of threatened species. Ndumo Game Reserve, in north-eastern KwaZulu-Natal, bordering Mozambique, has the third largest Nile Crocodile ( Crocodylus niloticus ) population in South Africa. Movement patterns of 50 Nile Crocodiles with a total length of between 202 cm and 472 cm were followed over a period of 18 months, using mark-resight, radio and satellite telemetry. The duration of radio transmitter attachment (131 ± 11.4 days) was significantly and negatively related to total length and reproductive status. Satellite transmitters failed after an average of 15 ± 12.5 days. Home range was calculated for individuals with 10 or more radio locations, spanning a period of at least 6 months. There was a significant relationship between home range size and total length, with sub-adults (1.5 m – 2.5 m) occupying smaller, more localised home ranges than adults (> 2.5 m). The largest home ranges were for adults (> 2.5 m). Home ranges overlapped extensively, suggesting that territoriality, if present, does not result in spatially discrete home ranges of Nile Crocodiles in Ndumo Game Reserve during the dry season. Larger Crocodiles moved farther and more frequently than smaller Crocodiles. The reserve acts as a winter refuge and spring breeding site for an estimated 846 Crocodiles, which also inhabit the Rio Maputo during the summer months. Nile Crocodile movement out of the reserve and into the Rio Maputo starts in November and Crocodiles return to the reserve as water levels in the floodplain recede in May. Conservation implications: Movement patterns of Nile Crocodiles show the important role the reserve plays in the conservation of Nile Crocodile populations within the greater Ndumo Game Reserve–Rio Maputo area.
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Habitat Use by Nile Crocodiles in Ndumo Game Reserve, South Africa: A Naturally Patchy Environment
Herpetologica, 2014Co-Authors: Peter M Calverley, Colleen T. DownsAbstract:Distribution patterns reflect the interactions of organisms with their environment. We discuss the distribution patterns of Nile Crocodiles (Crocodylus niloticus) in a naturally patchy floodplain environment with the use of aerial survey data collected over the last 40 yr. Although only 10,000 ha in size, Ndumo Game Reserve (NGR) supports one of the largest wild Crocodile populations in South Africa, largely because of landscape complementation with neighboring Mozambique. Distributions within the NGR were influenced by landscape physiognomy and composition as well as connectivity and corridor quality. To quantify the effects of environmental conditions on Crocodile distribution, we conducted 40 diurnal counts at Lake Nyamithi in the NGR between 2009 and 2012. Average monthly maximum temperature had an effect on the number of Crocodiles in Lake Nyamithi; however, environmental variables influenced different size classes of Nile Crocodiles to a varying extent. Anthropogenic disturbances influenced the functionality of the floodplain landscape negatively, with impacts on habitat use and connectivity. It is considered essential that a cross-border conservation program be initiated in order to conserve the current population of Nile Crocodiles in the greater NGR area.
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body temperature and basking behaviour of nile Crocodiles crocodylus niloticus during winter
Journal of Thermal Biology, 2008Co-Authors: Colleen T. Downs, Cathy Greaver, Ricky TaylorAbstract:Abstract The ability to thermoregulate in reptilians is often through behavioural modification. We investigated body temperature (Tb) patterns during winter in the amphibious Nile Crocodile (Crocodylus niloticus) and its relationship to basking behaviour at the St. Lucia Crocodile Centre, St. Lucia, South Africa. It was found that Crocodiles had no daily plateaus in Tb but rather continuous oscillations in Tb within a range of mean minimum Tb 18.8–19.6 °C to mean maximum Tb 26.9–29.2 °C. Crocodile Tb increased during the day, usually after 10:00 irrespective of body size. Behavioural data showed that the Crocodiles usually left the water to bask around 10:00. It is suggested that basking behaviour is important for elevating Tb rather than attaining a preferred Tb. The increased Tb may allow them to perform optimally when they return to water. The basking occurrence has management implications as it suggests that the best time to conduct aerial censuses of the St. Lucia Crocodiles is during winter after 10:00 when most of the individuals are basking and hence most easily seen.
Giuseppe La Rosa - One of the best experts on this subject based on the ideXlab platform.
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trichinella papuae in saltwater Crocodiles crocodylus porosus of papua new guinea
Emerging Infectious Diseases, 2004Co-Authors: Edoardo Pozio, Ifor L Owen, Gianluca Marucci, Giuseppe La RosaAbstract:To the Editor: Until 1995, reptiles were not known to be hosts of Trichinella; however, in that year Trichinella was detected in 40% of farm-raised Crocodiles (Crocodylus niloticus) in Zimbabwe. These Crocodiles were infected with a new species, T. zimbabwensis, which was experimentally infective in mammals, including primates (1). The infection of reptiles with Trichinella species that are potentially infective for humans has become more important since demand for the meat of Crocodiles, caimans, and alligators has increased in many areas of the world. This trend has resulted in the development of national breeding programs in more than 30 countries in North, Central, and South America; Africa; Asia; and Australia (2), which generated an income of approximately $60 million in 1998 (3). In 1999 in Papua New Guinea, wild and domestic pigs infected with a new species, T. papuae, were found (4,5); this new species was capable of completing its life cycle in reptiles that were infected experimentally (6). Trichinella infection has also been found in farm-raised saltwater Crocodiles (C. porosus) in Papua New Guinea, where a national program for Crocodile meat and skin products exists. Papua New Guinea has one Crocodile breeding farm that processes approximately 6,000 animals per year. Following the discovery of Trichinella-infected Crocodiles in Zimbabwe, the Australian government requested that Papua New Guinea conduct Trichinella testing on the Crocodile meat exported to Australia. Muscle samples from Crocodiles were digested by pepsin and HCl solution according to the standard technique (7). When available, approximately 100 larvae from each infected Crocodile were given by mouth to laboratory rats, and 10–20 larvae were stored in 90% ethyl alcohol for molecular identification. Multiplex polymerase chain reaction (PCR) was used to characterize the larvae, according to a published protocol (8). The primer set oTsr1 and oTsr4 was used to amplify the expansion segment V of the large subunit ribosomal RNA (9). The larvae of all Trichinella reference strains were used as controls. PCR products were gel-purified and directly sequenced by using the same primers as those used for PCR amplification. All sequences were aligned by using the Clustal W program from OMIGA 2.0 (Accelrys, San Diego, CA). Final alignment of the expansion segment V sequences was performed manually so microsatellites could be compared. Muscle samples from 118 saltwater Crocodiles (46 farm-born, 71 wild-born and farm-raised, and 1 killed in the wild near the Bensbach River) were tested. All samples from the farm-born Crocodiles were negative for Trichinella. Of the samples from the 72 wild-born Crocodiles (including the 1 killed in the wild), 16 (22.2%) were positive for Trichinella larvae, with an average of 7 larvae/g in the biceps. All of the infected Crocodiles originated in the Kikori area (Figure). The prevalence of Trichinella infection in Crocodiles from this area was 32.0% (16/50). Samples from the remaining 21 wild-born and farm-raised Crocodiles, and the 1 killed in the wild, were negative for Trichinella. These Crocodiles originated in nine different locations (Figure). Figure Papua New Guinea showing the areas of origin of the 72 wild-born saltwater Crocodiles (Crocodylus porosus): 1 each from Baimuru, Angoram, Timbunke, Kimbe, Bensbach River, and Buka; 2 from Labu; 7 from Wewak; 7 from Popondetta; and 50 from Kikori. PCR analysis showed that the parasites belonged to T. papuae. However, the Crocodile isolates differed from the reference strain of this species by the deletion of a TG dinucleotide and by a single base mutation (G vs. A) in the expansion segment V sequence. Testing for Trichinella in Crocodile meat has been conducted in Zimbabwe and Papua New Guinea only, and infected Crocodiles have been found in both countries. Crocodiles in other parts of the world are also likely to be infected. Since both T. zimbabwensis and T. papuae infection can develop in reptiles and mammals, eating Crocodile meat is a risk. In one region of Papua New Guinea, a high percentage of the local human population had anti-Trichinella antibodies (10). Moreover, the risk for human infection may be rising, given the increased marketing of meat from Crocodiles, caimans, and alligators in many parts of the world (2). The meat of other carnivorous reptiles, although consumed in very few areas, may also represent a source of infection, as suggested by the large number of larvae of both T. papuae and T. zimbabwensis in the muscles of experimentally infected monitor lizards (6). The presence of a TG dinucleotide in the expansion segment V sequence could be a useful marker for tracing the region of origin of infected meat. The infected Crocodiles, all of which were born in the wild, likely acquired infection before they arrived on the farm, since none of the farm-born Crocodiles was infected. In Zimbabwe, the source of infection was the Trichinella-infected Crocodile meat that had been fed to the other Crocodiles; the farm in Papua New Guinea does not engage in this practice, which would explain why none of its farm-born animals was infected. This study shows the importance of implementing measures to prevent the spread of Trichinella infection. For instance, since both T. papuae and T. zimbabwensis can be easily transmitted from Crocodiles to mammals, the discarded parts of Crocodiles should be properly destroyed to avoid transmission to synanthropic animals, and the waste products should not be fed to domestic animals, unless the products are frozen or cooked before use. Crocodile-breeding farms should adopt the artificial digestion method used in many countries to screen pigs for Trichinella infection (7). Freezing Crocodile meat, as practiced in Papua New Guinea, can also prevent infection because freezing destroys T. papuae and T. zimbabwensis larvae in muscles (1,4). By contrast, salting, drying, smoking, or preserving Crocodile meat in brine will not destroy trichinellae; these curing methods are not standardized, and the survival of Trichinella larvae can depend on factors such as salt concentration, moisture, and temperature (7). Similarly, Crocodile meat is frequently vacuum sealed, and the Trichinella larvae can retain their infectivity for several months in this environment (7).
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trichinella papuae in saltwater Crocodiles crocodylus porosus of papua new guinea
Emerging Infectious Diseases, 2004Co-Authors: Edoardo Pozio, Ifor L Owen, Gianluca Marucci, Giuseppe La RosaAbstract:To the Editor: Until 1995, reptiles were not known to be hosts of Trichinella; however, in that year Trichinella was detected in 40% of farm-raised Crocodiles (Crocodylus niloticus) in Zimbabwe. These Crocodiles were infected with a new species, T. zimbabwensis, which was experimentally infective in mammals, including primates (1). The infection of reptiles with Trichinella species that are potentially infective for humans has become more important since demand for the meat of Crocodiles, caimans, and alligators has increased in many areas of the world. This trend has resulted in the development of national breeding programs in more than 30 countries in North, Central, and South America; Africa; Asia; and Australia (2), which generated an income of approximately $60 million in 1998 (3). In 1999 in Papua New Guinea, wild and domestic pigs infected with a new species, T. papuae, were found (4,5); this new species was capable of completing its life cycle in reptiles that were infected experimentally (6). Trichinella infection has also been found in farm-raised saltwater Crocodiles (C. porosus) in Papua New Guinea, where a national program for Crocodile meat and skin products exists. Papua New Guinea has one Crocodile breeding farm that processes approximately 6,000 animals per year. Following the discovery of Trichinella-infected Crocodiles in Zimbabwe, the Australian government requested that Papua New Guinea conduct Trichinella testing on the Crocodile meat exported to Australia. Muscle samples from Crocodiles were digested by pepsin and HCl solution according to the standard technique (7). When available, approximately 100 larvae from each infected Crocodile were given by mouth to laboratory rats, and 10–20 larvae were stored in 90% ethyl alcohol for molecular identification. Multiplex polymerase chain reaction (PCR) was used to characterize the larvae, according to a published protocol (8). The primer set oTsr1 and oTsr4 was used to amplify the expansion segment V of the large subunit ribosomal RNA (9). The larvae of all Trichinella reference strains were used as controls. PCR products were gel-purified and directly sequenced by using the same primers as those used for PCR amplification. All sequences were aligned by using the Clustal W program from OMIGA 2.0 (Accelrys, San Diego, CA). Final alignment of the expansion segment V sequences was performed manually so microsatellites could be compared. Muscle samples from 118 saltwater Crocodiles (46 farm-born, 71 wild-born and farm-raised, and 1 killed in the wild near the Bensbach River) were tested. All samples from the farm-born Crocodiles were negative for Trichinella. Of the samples from the 72 wild-born Crocodiles (including the 1 killed in the wild), 16 (22.2%) were positive for Trichinella larvae, with an average of 7 larvae/g in the biceps. All of the infected Crocodiles originated in the Kikori area (Figure). The prevalence of Trichinella infection in Crocodiles from this area was 32.0% (16/50). Samples from the remaining 21 wild-born and farm-raised Crocodiles, and the 1 killed in the wild, were negative for Trichinella. These Crocodiles originated in nine different locations (Figure). Figure Papua New Guinea showing the areas of origin of the 72 wild-born saltwater Crocodiles (Crocodylus porosus): 1 each from Baimuru, Angoram, Timbunke, Kimbe, Bensbach River, and Buka; 2 from Labu; 7 from Wewak; 7 from Popondetta; and 50 from Kikori. PCR analysis showed that the parasites belonged to T. papuae. However, the Crocodile isolates differed from the reference strain of this species by the deletion of a TG dinucleotide and by a single base mutation (G vs. A) in the expansion segment V sequence. Testing for Trichinella in Crocodile meat has been conducted in Zimbabwe and Papua New Guinea only, and infected Crocodiles have been found in both countries. Crocodiles in other parts of the world are also likely to be infected. Since both T. zimbabwensis and T. papuae infection can develop in reptiles and mammals, eating Crocodile meat is a risk. In one region of Papua New Guinea, a high percentage of the local human population had anti-Trichinella antibodies (10). Moreover, the risk for human infection may be rising, given the increased marketing of meat from Crocodiles, caimans, and alligators in many parts of the world (2). The meat of other carnivorous reptiles, although consumed in very few areas, may also represent a source of infection, as suggested by the large number of larvae of both T. papuae and T. zimbabwensis in the muscles of experimentally infected monitor lizards (6). The presence of a TG dinucleotide in the expansion segment V sequence could be a useful marker for tracing the region of origin of infected meat. The infected Crocodiles, all of which were born in the wild, likely acquired infection before they arrived on the farm, since none of the farm-born Crocodiles was infected. In Zimbabwe, the source of infection was the Trichinella-infected Crocodile meat that had been fed to the other Crocodiles; the farm in Papua New Guinea does not engage in this practice, which would explain why none of its farm-born animals was infected. This study shows the importance of implementing measures to prevent the spread of Trichinella infection. For instance, since both T. papuae and T. zimbabwensis can be easily transmitted from Crocodiles to mammals, the discarded parts of Crocodiles should be properly destroyed to avoid transmission to synanthropic animals, and the waste products should not be fed to domestic animals, unless the products are frozen or cooked before use. Crocodile-breeding farms should adopt the artificial digestion method used in many countries to screen pigs for Trichinella infection (7). Freezing Crocodile meat, as practiced in Papua New Guinea, can also prevent infection because freezing destroys T. papuae and T. zimbabwensis larvae in muscles (1,4). By contrast, salting, drying, smoking, or preserving Crocodile meat in brine will not destroy trichinellae; these curing methods are not standardized, and the survival of Trichinella larvae can depend on factors such as salt concentration, moisture, and temperature (7). Similarly, Crocodile meat is frequently vacuum sealed, and the Trichinella larvae can retain their infectivity for several months in this environment (7).
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estimating population status and site occupancy of saltwater Crocodiles crocodylus porosus in the ayeyarwady delta myanmar inferences from spatial modeling techniques
Global Ecology and Conservation, 2020Co-Authors: Kay Zin Than, Colin T Strine, Tuanjit Sritongchuay, Alice C HughesAbstract:Abstract Saltwater Crocodiles Crocodylus porosus are listed as critically endangered in Myanmar because they are limited to Meinmahlakyun Wildlife Sanctuary (MKWS) in the Ayeyarwady delta region. Little contemporary data exists on their distribution and population size which hinders effective conservation and management. We conducted standardized spotlight surveys and camera trap surveys along the rivers inside MKWS, and two nearby reserved forests. We used Hierarchical N-mixture models, Spatial Count models, and the relative abundance index to estimate site use by and population sizes of saltwater Crocodiles in the Ayeyarwady delta. To address biases in detectability, we used maximum-likelihood and Bayesian approaches (1) to assess occupancy (site use) and population parameters of saltwater Crocodiles, and (2) to assay abiotic and anthropogenic factors affecting it. Saltwater Crocodiles were more likely to be abundant and occupy in the waterways inside MKWS than the reserved forests, and in the narrow and low salinity waterways than the wide and high salinity ones. Abundance of saltwater Crocodiles was lower in areas with the human settlements than in areas with no settlement. Creeks within MKWS had moderate salinity and no human settlement and therefore it can be regared as the last remaining optimal saltwater Crocodile habitat of the Ayeyarwady Delta. We estimated the saltwater Crocodile population sizes in MKWS were 75 ± 9.92 individuals as absolute spotlight index, 58 ± 8.02 individuals as the maximum likelihood estimate of the N-mixture models and 68 ± 10.00 individuals as the Bayesian estimate of the spatial count models. Current population estimates of saltwater Crocodiles are lower than the previously reported population size in 1999, and the declining population is now restricted to MKWS. We suggest developing buffer zones in the reserved forests around the wildlife sanctuary to increase habitat areas for saltwater Crocodiles and to improve the outlook for long-term saltwater Crocodile survival in Myanmar.