BMC Zoology最新文献

Big-scale sand smelt (Atherina boyeri) is an euryhaline pelagic schooling fish found throughout the Caspian Sea. A specialized fishery does not target this species, and its body length can reach up to 13 cm. A. boyeri serves as prey for many omnivorous and predatory fish and is one of the primary food sources for the Caspian seal (Pusa caspica). The objective of this study was to determine the size composition of A. boyeri in the diet of P. caspica, a declining species of the Caspian Sea. A coprological method was used, involving the collection of seal feces during spring and autumn haul-outs in the Northern and Middle Caspian, followed by examination of fish otoliths. Before this, otoliths from fish were analyzed to assess morphological diversity and growth patterns in relation to Atherina boyeri. Equations were developed to estimate fish length from otolith length and width. Otoliths from feces were classified into three wear categories: lightly, moderately, and heavily abraded. A comparison of otolith sizes from fish and feces allowed the calculation of wear coefficients based on otolith length for each group, which were incorporated into the reconstruction formula. The reconstructed fish length distribution showed that at the Northern Caspian haul-outs, individuals measuring 60-70 mm predominate, while at the Middle Caspian haul-out, individuals measuring 80-90 mm are most common. Overall, this is the first study to confirm that P. caspica feeds on both juvenile and mature A. boyeri, with lengths ranging from 23.1 to 117.1 mm.

Background: Leptospira are endemic and cause disease among California sea lions (Zalophus californianus), but the epidemiology of Leptospira in Galapagos sea lions (Z. wollebaeki) is almost completely unknown. Understanding the presence and circulation of this zoonotic pathogen is essential not only for the conservation of Galapagos sea lions, but also for assessing potential health risks to humans and other animals within the Galapagos archipelago. This study fills knowledge gaps by investigating Leptospira in this endemic host species to provide valuable insights into the dynamics of the pathogen in an isolated island ecosystem that is completely different from others in which Leptospira have been documented.

Results: In 2016, serological analyses detected 24 positive samples in the "El Malecón" rookery (n = 43) and 18 positive samples in the "Punta Pitt" rookery (n = 33), confirming exposure to pathogenic Leptospira species. In 2017, we identified 15 (n = 29) and 13 (n = 30) positive samples, respectively. Molecular analyses further detected leptospiral DNA in 70.8% (n = 24) of sand with urine samples and 45.8% (n = 24) of kidney samples. Amplicon sequencing of the secY gene fragment yielded 10 consensus sequences, confirming the circulation of Leptospira interrogans among Galapagos sea lions.

Conclusions: Our findings confirm that Galapagos sea lions are exposed to pathogenic Leptospira species and, for the first time, identify L. interrogans as the circulating species over two consecutive years. By expanding sampling across multiple rookeries, we provide a clearer picture of pathogen exposure in this endemic population. These results improve our understanding of Leptospira dynamics in marine mammals on remote islands, where management efforts aim to reduce disease risks from human activity, livestock, and synanthropic species.

The conservation of water is of great importance to terrestrial snails in order to survive in arid environments. However, evaporation of body water does occur, and it is unclear whether snails are able to actively reduce the evaporation or whether increased environmental temperature inevitably leads to increased evaporation. Physically, the quantity of evaporating water is largely determined by the temperature, the relative humidity and the velocity of the surrounding air, as well as the surface area of the evaporating body. Theba pisana, a widespread Mediterranean land snail, is exposed to a wide range of ambient temperatures. For this species the experimentally recorded evaporation rate per mass was tested as a 'response' variable to the 'explanatory' variables temperature, relative humidity and air velocity using multiple regression modelling. The variation in specific evaporation of T. pisana could be explained to 72.8% by these parameters. Threshold temperatures, which depended on the parameters relative humidity, air velocity and body size, were found to induce an active response in the snail that reduced their evaporation rate. A comparative analysis of the specific evaporation rate of different-sized snails shows that, at low temperatures, larger snails have a lower specific evaporation rate than smaller snails. However, above a threshold temperature this trend reversed, depending on air velocity and relative humidity. In general, the evaporation rate is lower at higher relative humidities. In the specified temperature range (23-35 °C) the snails tend to actively reduce the evaporation rate to conserve water rather than increase the evaporation rate to avoid overheating. These findings provide valuable information about the physiological adaptations that support survival in water-limited environments, offering important implications for understanding arid-adapted species such as desert snails.

Understanding the population dynamics and ecology of mammals ensures an effective conservation of wildlife. This study was conducted to examine the population status, structure, feeding ecology and habitat preference of common bushbuck (Tragelaphus scriptus decula) in Simien Mountains National Park, Ethiopia, covering both wet and dry seasons from August 2018 to March 2019. Data on the population structure and feeding ecology of common bushbuck was collected using a total count and focal sampling methods, respectively. Counting was done at three sites which have fourteen blocks. The collected data was analyzed using descriptive statistics and compared with Chi-square, the Kruskal-Wallis test, and Multivariate Analysis of Variance. The total number of common bushbucks in the study area was 99 and 102 during the wet and dry seasons, respectively. There was no significant difference (U = 7413, P < 0.340) in the number of individuals between wet and dry seasons. Of the total individuals observed, 64.5% constituted adults, 25.5% sub-adults and 9.8% unidentified sex. The study documented the consumption of 37 plant species over the study period which herbs comprised the highest proportion (62%), followed by shrubs (16.2%) and trees (13.5%). The most preferred species were Cyanotis barbata (12.29%) and Alchmila pedata (11.64%), whereas Gladiolus abyssinicus (0.14%) and Pterocephalus frutescens (0.2%) were the least consumed, respectively. The common bushbucks consumed mainly youngy leaves and shoots. However, there was a significant difference in plant part consumed by common bushbuck during wet and dry seasons ([Formula: see text]= 1762.3, df = 6, P < 0.05). To ensure the common bushbucks conservation in SMNP, we recommend the long term habitat and population monitoring and integrated research to inform broader ecosystem management and biodiversity protection.

Background: The lacertid genus Mesalina has been the subject of several phylogenetic and biogeographic studies as well as taxonomic revisions within the last decade. The genus is partitioned into seven main clades, some of which represent species complexes of morphologically very similar species. The Mesalina guttulata species complex is one such case. This complex currently comprises four described species that occur through Arabia and northern Africa, however, the presence of a cryptic species in Saudi Arabia, Kuwait, and Jordan was pointed out recently. For this study, we collected new material of the various species of the M. guttulata complex, including the undescribed lineage from across Saudi Arabia. We carried out multilocus phylogenetic analyses using three mitochondrial and three nuclear markers and analysis of morphological data to verify whether the undescribed lineage deserves a species rank.

Results: The results show that the lineage is clearly genetically separated from the other species of the complex and shows morphological differentiation from the other species. Therefore, we describe it herein as a new species, Mesalina cryptica sp. nov.

Conclusions: We contribute to the taxonomy of Arabian lacertid lizards by describing a new species distributed in central Saudi Arabia, with isolated populations occurring in Kuwait and Jordan. Despite its large range, the species is genetically and morphologically homogeneous. The gap in its distribution between the Jordan and Saudi Arabia populations is ascribable to the paucity of sampling along the Saudi/Iraqi border.

Background: Human-primate conflict is a global conservation challenge, particularly in densely populated, low-income countries like Ethiopia. The Omo River Valley forest belt, spanning across the Omo River in Ethiopia to Lake Turkana in Kenya, harbors a diverse array of African primate species. An investigation on non-human primate population density and human primate conflict was carried out from January 2022 to December 2023 in the Tembaro Community Conserved Forest, Omo River basin, South Central Ethiopia. The population density of non-human primates was estimated using distance sampling method, and the intensity of conflict among human-primate was quantified by a questionnaire survey and focus group discussions.

Results: The study revealed some interesting results which include the presence of black colobus monkeys (Colobus satanas) in Ethiopia. The mean density of Anubis baboons (Papio anubis) was 10.06 ± 2.93, grivet monkeys (Chlorocebus aethiops) 17.09 ± 4.53, black colobus monkeys (Colobus satanas) (vulnerable primate species in Africa) was 8.3 ± 1.20, and mantled guerezas (Colobus guereza) was 14.76 ± 3.57 individuals/km². Crop damage and livestock predation were prevalent issues in the present study area. Majority of the local village respondents (51.96%, n = 146) reported that crop damage was the common cause of human-primate conflict, followed by livestock predation and crop damage (33.5%, n = 94). Majority of the conflict was caused by Anubis baboon (Papio anubis) (41%, n = 115), followed by grivet monkeys (Chlorocebus aethiops) (33.1%). The most common cultivated crop by farmers in the study area and the most damaged by the non-human primates was maize (Zea mays) (33.5%, n = 94). The average estimated loss of crops was US$ 6544.50 per year. The average annual loss incurred by each household due to primates predation on their small animals was 94.19 US$. Physical guarding (33%, n = 93) was chosen as the most effective strategy to prevent crop damage and livestock predation.

Conclusion: This study provides valuable insights into primate ecology and the challenges they pose to local communities. The findings reveal varying primate population densities, with Grivet monkeys exhibiting the highest densities. These primate densities contribute significantly to human-wildlife conflict, primarily through crop foraging and livestock predation. While traditional mitigation methods are currently in place, a more sustainable and integrated approach is urgently needed to ensure the harmonious coexistence of primates and local communities. The findings of this study are crucial for developing effective conservation and conflict mitigation strategies that will safeguard the long-term survival of both primates and the livelihoods of local people.

Clinical trial number: Not applicable.

Background: Hippopotamus (Hippopotamus amphibious) is a semi-aquatic mammal that is considered the third largest living land mammal still alive on earth. The main objective of this study was to determine the distribution range and human-hippopotamus conflicts in the Lake Tana Biosphere Reserve, Ethiopia. Data were collected from June 2022 to January 2023. Total count methods were used to estimate the hippopotamus population, and Arc GIS was used to determine the distribution range and habitat suitability of hippopotamus. Structured questionnaire and focus group discussions were used to collect data on human-hippopotamus conflict. Data were analysed using One-way ANOVA, independent t-test, and chi-sqaure test.

Results: The mean population estimation of hippopotamus in in the study area showed 252.67 ± 15.9 with a density of 0.072 individuals per km². The suitable slope analysis of hippopotamus along the the Lake Tana Biosphere Reserve's shoreline revealed that 4.7% of the shoreline was most suitable, 48.4% moderately suitable, and 46.9% not suitable. Variations in the hippopotamus' habitat suitability within the study area have been associated with a number of factors including availability of water, food, elevation, and vegetation cover. Crop raiding and overgrazing were the primary causes for conflict.

Conclusion: In order to conserve hippopotamus in the in the Lake Tana Biosphere Reserve, appropriate conservation measures including habitat protection and restoration, and community engagement and education need to be developed. Moreover, further research on the ecological aspects of the Lake's ecosystem is required to ensure the conservation of hippopotamus.

Background: The Prussian carp (Carassius gibelio) is an invasive fish species from Eurasia that was first found in North America in the Canadian province of Alberta in the early 2000s. In 2018, an established population of Prussian carp was discovered in the neighboring province of Saskatchewan, raising concern for additional spread in Canada and to the USA.

Results: Prussian carp in Saskatchewan have colonized the South Saskatchewan River and tributaries and are moving towards additional connected systems to the northeast. Direct access to most of southern Saskatchewan and the USA is currently prevented only by the Qu'Appelle Dam on the South Saskatchewan River at Lake Diefenbaker. Prussian carp populations in Saskatchewan were age-stratified and ranged from hatch size (20 mm) to a maximum of 42.5 cm total length. Aging using otoliths and scales was unreliable, but the largest fish collected were likely > 10 years old. Saskatchewan Prussian carp had mixed ploidies with diploid, triploid, and tetraploid individuals intermixed. In Lake Diefenbaker, only adult female and juvenile fish were detected, but males were present in the Anerley Lakes at low relative abundance. Emergence of young of the year Prussian carp began in early July and continued through August, indicating an extended period of reproduction; however, most spawning likely occurred during mid-June. The timing of spawning overlaps with that of a variety of native sucker and shiner species, but sperm donors for potential gynogenesis remain unidentified.

Conclusion: Our findings suggest that invasive Prussian carp are well established in Saskatchewan and will likely use provincial waterbodies as a conduit to colonize more areas in North America.

Land use changes can have morphological and physiological impacts on wildlife. This study aimed to explore the influence of anthropogenic land use on the morphology and corticosterone concentrations in two songbirds endemic to the Galapagos archipelago: the granivorous Small Ground Finch Geospiza fuliginosa and the insectivorous Galapagos Yellow Warbler Setophaga petechia aureola in San Cristobal Island. Birds were caught and measured between June and August 2018 and June and July 2019 across four areas with different human land uses: urban green areas in the coastal town of Puerto Baquerizo Moreno, natural deciduous forest in the lowlands, agricultural areas in the highlands, and seasonal evergreen forest in the highlands. Morphological comparisons among study areas were made using ANOVA or the Kurskall-Wallis test. Corticosterone levels obtained from tail feathers were measured with an ELISA test. Linear regression models were employed to explore the effects of the different human land uses on corticosterone concentrations. For G. fuliginosa, we found significant differences (p < 0.05) in weight, wing, and tarsus length between natural and disturbed habitats. The linear regression results showed higher corticosterone concentrations in urban G. fuliginosa than those in agricultural and natural habitats. Additionally, higher corticosterone concentrations were found in finches captured in 2018, a year with much higher precipitation than in 2019. For S. petechia aureola, the only significant difference (p < 0.05) between areas was a wider beak in birds captured in the seasonal forest compared to those from urban areas. Although our sample size does not allow for definitive conclusions, our results provide evidence that the ecology of each species plays a crucial role in shaping their morphological and physiological responses to land use changes and seasonal environmental changes.

The amphipod Parhyale hawaiensis is a tropical species and of interest for use as a live feed in warm water marine aquaculture. Prior to the establishment of large scale culture optimal culture conditions need to be determined. The effects of temperature (20 °C, 23 °C, 26 °C, and 29 °C) on juvenile growth, survival, and generation time of the marine amphipod P. hawaiensis were assessed in this study. Growth was followed for 12 weeks, survival for 16 weeks and hatchling-to-hatchling generation time for 20 weeks. During juvenile production data concerning precopula behavior and mating pair productivity were obtained. Higher growth (length, weight) was seen at 26 °C (4.4 ± 0.58 mm, 2.8 ± 1.4 mg) and 29 °C (4.6 ± 0.8 mm, 2.3 ± 0.89 mg) and higher survival at 23 °C (25.2 ± 12.2%) and 26 °C (31.9 ± 3.2%). The hatchling-to-hatchling generation time at 26 °C and 29 °C was 16 weeks but was not determined at lower temperatures, as no hatchlings were observed by 20 weeks. Mating pairs were formed within two days and the productivity rate of mating pairs was 1.32 ± 0.31 juveniles per pair, at ambient room temperature (~ 21 °C). The data suggests culturing P. hawaiensis at 26 °C would enhance production. This study provides valuable data that may be used to establish large-scale production of this species.