Article
Environmental Sciences
Marc Humphries, Jan Myburgh, Robert Campbell, Xander Combrink
Summary: Lead exposure is a significant threat to Nile crocodiles at Lake St Lucia in South Africa. Male crocodiles have higher blood lead concentrations compared to females, and blood lead concentrations are correlated with lead concentrations in tail fat tissue. High lead concentrations have severe impacts on crocodile health, leading to anemia and tooth problems.
Article
Environmental Sciences
Marc S. Humphries, Jan G. Myburgh, Robert Campbell, Archibold Buah-Kwofie, Xander Combrink
Summary: Nile crocodiles at Lake St Lucia in South Africa show significant accumulation of organochlorine pesticides in their fat tissues, with higher concentrations in wild individuals compared to captive ones. The presence of p,p'-DDE, a major metabolite of DDT, was found to be strongly correlated with body length. Differences in residue levels and profiles suggest potential impacts of environmental changes on pesticide exposure in crocodiles.
SCIENCE OF THE TOTAL ENVIRONMENT
(2021)
Article
Environmental Sciences
Dawn Cory-Toussaint, Peter J. Taylor, Irene E. J. Barnhoorn
Summary: Bats have been proposed as reliable bioindicators for monitoring bioaccumulation of elements and chemicals in ecosystems, with non-invasive methods becoming more popular. This study found significantly higher concentrations of certain elements in bats from a mining footprint compared to a reference area, suggesting the potential of fur and blood as indicators of environmental toxicity. Further research is needed to explore toxic thresholds and unknown factors related to element concentrations in bat tissues and organs.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Multidisciplinary Sciences
Anthony Valverde, Olivier Castro-Morales, Monica Madrigal-Valverde, Marlen Camacho, Vinicio Barquero, Carles Soler, Eduardo R. S. Roldan
Summary: Limited use of computer assisted semen analysis (CASA) for evaluating reptile sperm was observed. The study analyzed sperm kinematic variables in American crocodile semen samples and identified distinct subpopulations based on velocity, progressiveness, and oscillation. Variability among males in kinematic subpopulations suggests potential for future development of assisted reproduction techniques for crocodiles, utilizing CASA technology.
Article
Biochemistry & Molecular Biology
Amin Gholamhosseini, Mahdi Banaee, Siyavash Soltanian, Fahimeh Sakhaie
Summary: This study measured concentrations of heavy metals in blood serum and feces of mugger crocodile and in water and sediment of their habitat in Iran. The analysis showed the highest levels of heavy metals in crocodile serum, feces, water, and sediment, with variations in metal concentrations between male and female crocodiles, and negative correlations between sex and bioconcentrations of certain metals. The study concluded that the environmental conditions in the Negour lagoons are not suitable for crocodiles and could pose a health risk to both the reptiles and the residents who rely on the lagoons for water and seafood.
BIOLOGICAL TRACE ELEMENT RESEARCH
(2022)
Article
Food Science & Technology
Krittika Srisuksai, Kongphop Parunyakul, Pitchaya Santativongchai, Narumon Phaonakrop, Sittiruk Roytrakul, Phitsanu Tulayakul, Wirasak Fungfuang
Summary: Crocodile oil is rich in monounsaturated fatty acids and polyunsaturated fatty acids, which have antioxidant and cognitive effects. This study investigated the effect of crocodile oil on antioxidant activity and cognitive function in rats. The results showed that crocodile oil significantly decreased triglyceride levels and had stronger free radical scavenging ability compared to olive oil. It also improved memory function in rats without causing a decline in cognitive function. Therefore, crocodile oil can be considered as an alternative dietary oil with hypolipidemic and antioxidant effects.
Article
Environmental Sciences
Rajendran Rajaram, Arumugam Ganeshkumar, Partheeban Emmanuel Charles
Summary: This study determined the concentrations of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in various components of the Kongsfjorden Fjord and freshwater lakes in Ny-Alesund, Svalbard archipelago, in order to assess the anthropogenic impacts of Ny-Alesund town. The results showed that Cu and Zn were detected in the water samples, while Zn, Cu, and Cr were found in the plankton samples, and the concentrations of metals in macroalgae and sediments varied. Multivariate statistical analyses indicated that the metals originated from both anthropogenic and geogenic sources. Pollution monitoring indices revealed high levels of contamination in the study area, primarily due to anthropogenic activities.
Article
Multidisciplinary Sciences
Jose Antonio Lemos Barao-Nobrega, Mauricio Gonzalez-Jauregui, Robert Jehle
Summary: Estimates of local abundance and overall population size of Morelet's crocodiles in the Calakmul region of Mexico were quantified using traditional approaches and N-mixture models. The study found that the ZIP model provided superior confidence in detection and abundance estimation.
Article
Fisheries
Muhammad Nafees Ur Rehman, Yu Wang, Jiwen Pan, Yu Han, Nuo Yang, Xin Wang, Lixia Fan, Qian Li, Feifei Yin, Peng Wang, Weixin Zeng, Ting Zheng, Jifeng Zeng, Guiying Guo, Jiping Zheng
Summary: The study described the histopathological and etiological aspects of Edwardsiella tarda infection in farmed hatchling Siamese crocodiles in Hainan, China. Isolates of E. tarda from various internal organs showed positivity for virulence and antibiotic resistance genes, notably tetracycline resistance genes. Biofilm formation was highlighted as a key virulent factor in the pathogenesis of E. tarda.
Article
Agriculture, Dairy & Animal Science
Devon M. Viljoen, Edward C. Webb, Jan G. Myburgh, J. Christoff Truter, Jeffrey W. Lang, Albert Myburgh
Summary: The study assessed the ambient temperatures for captive adult Nile crocodiles on a commercial farm in South Africa and developed non-invasive data capture techniques. The findings showed that crocodiles' material selection varied with season, time, and climate conditions, and there was a significant correlation between their back temperatures and positional temperatures.
APPLIED ANIMAL BEHAVIOUR SCIENCE
(2023)
Article
Environmental Sciences
Ekrem Bolukbasi, Mehmet Karakas
Summary: Heavy metals are toxic and widely distributed in the environment. This study investigated the toxic effects of copper heavy metal on safflower plants in terms of genetic and epigenetic parameters. The results showed that high doses of copper had genotoxic effects on the safflower genome. Epigenetic analysis revealed different methylation patterns, indicating that changes in methylation can serve as a mechanism of protection against copper toxicity. Safflower can also be used as a biomarker to determine soil pollution caused by copper heavy metal.
Article
Zoology
James E. Loudon, Alycia E. Lewis, Trudy R. Turner, Michaela E. Howells, Alysha Lieurance, Jack E. Pender
Summary: This study analyzed the concentrations of toxicants in vervet monkey hair samples collected from different habitats in South Africa and found that anthropogenic disturbance has an impact on the concentrations of lead and arsenic. Two systems were used to categorize the degree of disturbance, based on behavioral observations, home range overlap, interviews, and stable isotope analysis. The results suggest that using both qualitative and quantitative data is essential for estimating the relationship between anthropogenic disturbance and environmental toxicants.
Article
Fisheries
Brandon Sideleau, Tamen Sitorus, Dadang Suryana, Adam Britton
Summary: Research findings indicate that there is a high incidence of saltwater crocodile attacks in East Nusa Tenggara province, with 60% being fatal incidents and mostly affecting males during fishing. The study also reveals generally positive cultural attitudes towards crocodiles locally, but recent media stories have introduced some negative beliefs and fears.
MARINE AND FRESHWATER RESEARCH
(2021)
Article
Environmental Sciences
Janita Bosch, Carlos Bezuidenhout, Roelof Coertze, Lesego Molale-Tom
Summary: This study investigated the physico-chemical properties, antimicrobial resistance characteristics, and heterotrophic bacteria levels in the Wonderfonteinspruit and Mooi River systems in South Africa. The results suggest that metal pollution from mining may contribute to the co-selection and maintenance of metal and antibiotic-resistant bacteria in the aquatic environment.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2023)
Article
Cell Biology
Hao Li, Karin Staxang, Monika Hodik, Karl-Gunnar Melkersson, Helge Rask-Andersen
Summary: This study investigates the fine structure of the crocodile auditory organ and describes the presence of a vascularized epithelium separate from the tegmentum vasculosum. It is believed that this vascularized epithelium secretes endolymph and generates a low grade endocochlear potential in crocodiles.
FRONTIERS IN CELL AND DEVELOPMENTAL BIOLOGY
(2023)
Article
Ecology
Ndivhuwo Shivambu, Tinyiko C. Shivambu, Colleen T. Downs, Sandi Willows-Munro
Summary: This study assessed the taxonomy and genetic diversity of 149 rodents sold in pet shops across South Africa using mitochondrial gene regions. The findings revealed that non-native species are widely distributed in the South African pet trade industry, while the trade of native species is regulated.
AFRICAN JOURNAL OF ECOLOGY
(2023)
Article
Engineering, Environmental
David Ehlers A. Smith, Yvette C. Smith, Harriet T. Davies-Mostert, Lindy J. Thompson, Daniel M. Parker, Deon de Villiers, Dean Ricketts, Brent Coverdale, Peter J. Roberts, Christopher Kelly, Duncan N. Macfadyen, Nomthandazo S. Manqele, R. John Power, Colleen T. Downs
Summary: During the COVID-19 pandemic, lockdown restrictions were believed to have potential benefits to wildlife, but concerns were raised about the impact on nature conservation. This study examined the effects of these restrictions on biodiversity conservation in South Africa, a country with rich biodiversity but also economic inequality and reliance on wildlife resources. Expert opinions were gathered using a structured questionnaire based on the IUCN's Threats Classification Scheme, and supported by case studies from both government and non-governmental conservation organizations. The most commonly reported threats were related to biological resource use, developments, invasive species, and human intrusions. Lack of tourism revenue and funding were identified as barriers to conservation efforts. The study calls for the implementation of mechanisms to prevent environmental degradation during global emergencies, in order to protect conservation efforts.
Article
Ecology
Jesse M. Alston, Christen H. Fleming, Roland Kays, Jarryd P. Streicher, Colleen T. Downs, Tharmalingam Ramesh, Bjorn Reineking, Justin M. Calabrese
Summary: Resource selection functions (RSFs) are widely used in animal ecology, but autocorrelation in tracking data can lead to biased estimates and narrow confidence intervals. This study proposes a likelihood weighting method to mitigate the negative effects of autocorrelation on RSFs. The method improves the quality of inferences derived from RSFs and provides a workflow for applying the method to animal tracking data.
METHODS IN ECOLOGY AND EVOLUTION
(2023)
Article
Ecology
Mbalenhle T. Sosibo, David Ehlers A. Smith, Yvette Ehlers C. Smith, S. Thobeka Gumede, Samukelisiwe P. Ngcobo, Colleen T. Downs
Summary: Microhabitats are crucial for the persistence of mammalian species and communities. This study focuses on the forest biome in South Africa and investigates the microhabitat characteristics that influence the presence and absence of mammalian species. Camera traps were used to monitor the species and data on vegetation were collected. The results highlight the importance of leaf litter, crown closure, and grass cover in supporting the presence and persistence of large and medium-sized mammals in the Southern Mistbelt Forests.
AFRICAN JOURNAL OF ECOLOGY
(2023)
Article
Ecology
Camille J. A. Fritsch, Jarryd P. Streicher, Colleen T. Downs
Summary: The common hippopotamus is an important player in African savannah ecosystems, but the ecological impacts of hippos lack behavioral data. In this study, GPS transmitters were used to track male hippos in Kruger National Park, South Africa, revealing smaller home range sizes than previously documented. This research provides valuable baseline behavioral data for managing hippos in Kruger National Park and southern Africa.
AFRICAN JOURNAL OF ECOLOGY
(2023)
Article
Ecology
Philip R. Jordaan, John Measey, Catharine C. Hanekom, Xander Combrink
Summary: The increase in the number of mesoherbivores and their impact on the ground cover led to a decline in the density of fossorial herpetofauna in Ndumo Game Reserve during the early 2000s. Despite a significant decline in mesoherbivore numbers, there was no significant increase in the two most common soil-living reptiles. This suggests that either fossorial herpetofauna numbers increase slowly or the initial survey methods were not comparable.
AFRICAN JOURNAL OF ECOLOGY
(2023)
Article
Multidisciplinary Sciences
Everton B. P. de Miranda, Carlos A. Peres, Luiz Gustavo Rodrigues Oliveira-Santos, Colleen T. Downs
Summary: Apex predators like harpy eagles in Amazonian Forests affect nutrient distribution through deposition of prey carcasses and excreta. Surprisingly, their nests had negative effects on soil nutrient profiles, but canopy tree leaves around nests showed significant increases in nitrogen, phosphorus, and potassium. This study highlights the importance of understanding the ecological role of central-place foragers in nutrient deposition and ecosystem stability.
SCIENTIFIC REPORTS
(2023)
Article
Biodiversity Conservation
Ntaki D. Senoge, Colleen T. Downs
Summary: In this study, the use of cellular telecommunication towers as nesting sites by pied crows in Pietermaritzburg, South Africa was investigated. It was found that out of 36 towers, 17 were used as nesting sites by the crows. The presence of cropland, forest, grassland, schools and relief were important factors influencing the choice of nesting sites.
Article
Biodiversity Conservation
Donald T. McKnight, Kendall Ard, Renoir J. Auguste, Gaurav Barhadiya, Michael F. Benard, Paige Boban, Martin L. Dillon, Colleen T. Downs, Brett A. DeGregorio, Brad M. Glorioso, Rachel M. Goodman, Coen Hird, Ethan C. Hollender, Malcolm Kennedy, Rosie A. Kidman, Andrhea Massey, Pearson McGovern, Max Muehlenhaupt, Kayhan Ostovar, Danusia Podgorski, Cormac Price, Beth A. Reinke, Louise M. Streeting, Jane Venezia, Jeanne Young, Eric J. Nordberg
Summary: Recent studies have found that some species of freshwater turtles engage in nocturnal basking behavior, suggesting that environmental temperature may play a role in this behavior. We conducted a global collaborative effort to document and quantify basking activity in various freshwater turtle species. Our study revealed that 13 species engaged in nocturnal basking, primarily in tropical and sub-tropical locations. The frequency and duration of nocturnal basking varied among species and seasons, with events often being longer than diurnal basking.
GLOBAL ECOLOGY AND CONSERVATION
(2023)
Article
Anatomy & Morphology
Albert Myburgh, Jan Myburgh, Johan Steyl, Colleen T. Downs, Hannes Botha, Liam Robinson, Stephan Woodborne
Summary: In this study, the histology and growth patterns of Nile crocodile claws were investigated, revealing similarity to other reptilian claws and an age profile. The study also validated previous dietary reconstruction assumptions using radiocarbon dating. This research contributes to understanding the role of Nile crocodile claws in dietary reconstruction studies and emphasizes the importance of age-related assumptions.
JOURNAL OF MORPHOLOGY
(2023)
Article
Environmental Sciences
Matthew J. Burnett, Vanessa Suessle, Terence Saayman, Graham Jewitt, Gordon C. O'Brien, Colleen T. Downs
Summary: Fish behaviour data is an important indicator for assessing freshwater ecosystem status. The use of activity sensors and the EWMA model allows for real-time monitoring and management of fish behaviour changes, combined with environmental data, to improve freshwater management.
RIVER RESEARCH AND APPLICATIONS
(2023)
Article
Ecology
Nasiphi Bitani, Craig P. Cordier, David A. Ehlers Smith, Yvette C. Ehlers Smith, Colleen T. Downs
Summary: Forest transformation has significant impacts on biodiversity and ecosystem functioning. This study investigated the influence of forest structure and composition on bird species community structure and functional diversity. The results showed that forest patches with high structural complexity and tree species richness had higher functional richness. Different forest characteristics influenced habitat use by different bird species, and tree species diversity had positive effects on some species while negative effects on others.
ECOLOGY AND EVOLUTION
(2023)
Article
Biodiversity Conservation
Kerushka R. Pillay, Jarryd P. Streicher, Colleen T. Downs
Summary: Urbanisation generally has a negative impact on biodiversity, but some species, like the vervet monkey, thrive in urban areas. In this study, we used GPS transmitters to track vervet monkeys in an urban forest mosaic landscape in Durban, South Africa. The monkeys had relatively small home range sizes and preferentially used forest, thicket, and built-up habitats. The spatial ecology of urban vervet monkeys provides important information for future management interventions and addressing human-monkey conflicts.
Article
Biodiversity Conservation
Kyrone K. Josiah, Colleen T. Downs
Summary: The study "Nesting Ecology of Spotted Thick-knee in an Urban Mosaic Landscape in Pietermaritzburg, South Africa" examined the nesting behavior of the bird species in urbanized areas. The research found that Spotted Thick-knee showed preferences for certain habitats and nest sites, with successful nesting outcomes being significantly higher than failed outcomes. Incubation activity was longer during the day and negatively impacted by disturbance in human-modified habitats.
GLOBAL ECOLOGY AND CONSERVATION
(2023)
Review
Zoology
Jonah Gula, Colleen T. Downs
Summary: The nests of the Hammerkop bird play a key role in the breeding biology of other avian species. At least 20 different bird species across 18 African countries use Hammerkop nests for breeding.