Feeding Habits Research Articles

Marine migration, thermal habitat use and feeding habits of Arctic charr (Salvelinus alpinus (L. 1758)) in SW Greenland

Climate change is altering northern coastal aquatic habitats, especially in fjords. Data on current ecosystem structure and biodiversity in many northern fjord and coastal ecosystems, especially for Greenland, are lacking. We used acoustic telemetry combined with stable isotope analyses in a southwest Greenland fjord to investigate marine migrations, marine and freshwater thermal habitat use, and the marine feeding habits of 80 acoustically tagged Arctic charr over one year. During summer, most Arctic charr occupied the inner fjord. Models of Arctic charr thermal habitat use suggested higher experienced water temperatures in the inner compared to outer fjord (estimated 1.59ºC difference) during tagged charr mean 70-day (S.D.=14 days) residencies. During February and March, non-migratory individuals used warmer waters (+ 0.56ºC higher) than fish that ultimately migrated to sea, suggesting that over-wintering habitat use patterns influenced migration tactics. Stable isotope mixing model analysis indicated that Arctic charr fed mainly on capelin, marine gammarids and three-spine sticklebacks. The results provide a contemporary baseline for assessing predictions of potential changes in the ecology of Arctic charr in SW Greenland fjords.

Molecular Cloning of the scd1 Gene and Its Expression in Response to Feeding Artificial Diets to Mandarin Fish (Siniperca chuatsi).

Background/Objectives: Stearoyl-coenzyme A desaturase 1 (SCD1) plays a crucial role in fatty acid metabolism. However, its roles in the feeding habit transformation of mandarin fish (Siniperca chuatsi) remain largely unknown. Methods: Juvenile mandarin fish (10.37 ± 0.54)g were trained to feed on an artificial diet and then divided into artificial diet feeders and nonfeeders according to their feed preference. Afterwards, the scd1 gene of mandarin fish (Sc-scd1) was identified and characterized, and its transcription difference was determined between S. chuatsi fed live artificial diets and those fed prey fish. Results: Our results show that Sc-scd1 coding sequence is 1002 bp long, encoding 333 amino acids. The assumed Sc-SCD1 protein lacks a signal peptide, and it contains 1 N-linked glycosylation site, 24 phosphorylation sites, 4 transmembrane structures, and 3 conserved histidine elements. We found that Sc-SCD1 exhibits a high similarity with its counterparts in other fish by multiple alignments and phylogenetic analysis. The expression level of Sc-scd1 was detected with different expression levels in all tested tissues between male and female individuals fed either live prey fish or artificial diets. Conclusions: In particular, the Sc-scd1 expression level was the highest in the liver of both male and female mandarin fish fed artificial diets, indicating that scd1 genes may be associated with feed adaption of mandarin fish. Taken together, our findings offer novel perspectives on the potential roles of scd1 in specific domestication, and they provide valuable genetic information on feeding habits for the domestication of mandarin fish.

Niche partitioning of invasive Amur sleeper (Perccottus glenii) amongst native fish communities in three different freshwater ecosystems

The invasive fish, Amur sleeper, poses a significant and growing threat to Central European freshwater ecosystems. Despite its rapid spread, the ecological implications of its invasion have been poorly explored. Recent findings confirm its presence in various Estonian freshwater systems, raising concerns about its imminent expansion into larger lakes. To better understand its potential ecological impacts, we explored the isotopic niche of the Amur sleeper in comparison with native fish species co-existing in three Estonian freshwater ecosystems. We employed carbon and nitrogen stable isotope analyses alongside gut content analyses. Our findings show that the Amur sleeper’s diet in newly-invaded Estonian water bodies predominantly comprises benthic macroinvertebrates, although it may also include fish, confirming its role as a predator in the local food web. Notably, Amur sleeper populations exhibited clear isotopic niche partitioning in three invaded ecosystems. A logistic regression model, based on stomach content analyses, revealed an ontogenetic diet shift from benthivorous to piscivorous feeding habits from small to large specimens. Amur sleeper exhibits voracious, non-selective feeding habits, which can negatively impact native freshwater communities. The ability to occupy a distinct isotopic niche, with minimal overlap with native fish populations, may reduce interspecific competition, facilitating the spread and establishment of Amur sleeper in newly-invaded habitats. Managing the spread of this invasive species thus becomes even more critical to safeguard the integrity of native aquatic ecosystems.

Feeding mode drives mandibular shape in extant Delphinidae

AbstractDelphinidae is the most diverse family within the toothed whale clade, displaying two biosonar modes, different feeding strategies, and diving and habitat adaptations. This work examines the delphinid mandible to determine the association between shape, size and ecological variables in extant species. Geometric morphometric analysis on 95 mandibles belonging to 30 (out of 38) extant species, representatives of all 17 extant genera, was performed in occlusal (or dorsal) and lateral (or labial) view. The results reveal that feeding mode and climate primarily drive mandibular shape in extant species. Biosonar mode is an evolutionary driver in mandibular shape in occlusal view, while diet and maximum prey size play a significant role in size only in both views. By contrast, Diving Ecology, Superficial Temperature and Rostral index do not play a significant role in driving delphinid mandibular shape and size.

Opportunistic predatory feeding behaviour of Munida intermedia A. Milne-Edwards & Bouvier, 1899 targeting juveniles of Lepidopus caudatus (Euphrasen, 1788) in the north-western Mediterranean Sea

The genus Munida, inhabits various marine habitats and exhibits versatile feeding behaviour. This study explored the behavioural patterns of Munida intermedia, shedding light on its opportunistic behaviour and competitive interactions within its ecological niche. In 2018, during an investigation using a remotely operated vehicle (ROV), carried out on the Méjean shoal (north-western Mediterranean Sea), at 397 m depth, specimens were observed engaging in opportunistic predatory feeding, targeting juveniles of the bathypelagic silver scabbardfish Lepidopus caudatus. Our findings underscore the dynamic nature of M. intermedia feeding habits and the significant role of competitive interactions within its habitat, highlighting the role of video technology in capturing real-time information.

Food and Feeding Habits of Two Dominant Fish Species in Ureje Reservoir Ado-Ekiti, Ekiti State, Nigeria

Food and Feeding Habits of Two Dominant Fish Species in Ureje Reservoir Ado-Ekiti, Ekiti State, Nigeria

Ecological restoration amplifies riverine fish catch of Gudusia chapra (Hamilton, 1822): an impact study in the river Ganga using multivariate statistical tools and water quality indices.

Fish residing in the aquatic ecosystem are considered the best ecological indicator for monitoring environmental habitat. To evaluate the changes that occurred due to relative restoration in the ecological habitat, a study was conducted in the freshwater zone of the river Ganga between Buxar, Bihar, and Ballia, Uttar Pradesh, between July 2021 and July 2022. In the monitoring, the physico-chemical condition, as well as the food and feeding habits of the fish Gudusia chapra, were monitored with the help of various pollution evaluating indices, namely, the algal pollution index (API) for planktons, the comprehensive pollution index (CPI-WQI), and the National Sanitation Foundation Water Quality Indices (NSF-WQI) for water. The study showed that the relative restoration facilitated the amplification of the fish catch from 5.60 to 98.98% in two consecutive years. The reduction in the API (15 to 4) as well as CPI (0.80 to 0.72) during both years signified the reduction of the pollution status of the river in the region. The NSF-WQI also decreased from 88.27 to 79.27 from 2021 to 2022. The electivity index for the fish showed that fish preferred the groups Cyanobacteria, Rotifera, and Copepoda. The multivariate, as well as univariate analyses, revealed that the fish G. chapra is significantly influenced by multiple abiotic as well as biotic variables, among which the major contributors are riverine velocity, transparency, conductivity, pH, dissolved oxygen, total alkalinity, carbonate, bicarbonate, salinity, total hardness, calcium, silicate, and biochemical oxygen demand.

Early oral colonization of streptococcus mutans and lactobacilli species in infants: Investigating the relationship with maternal and environmental factors, from birth through the sixth month.

To assess the presence of Streptococcus Mutans (S.mutans) and Lactobacillus species (LB) of newborn-mother pairs using the real time polymerase chain reaction (qRT-PCR). Subjects were selected from the patients followed in the Neonatology Clinic of Akdeniz University's Faculty of Medicine between the years 2017-2018. First samples collected within 48 hours after birth, and second samples were at six months. The samples were analyzed for the presence of S.mutans and LB using qRT-PCR. Mothers' smoking habits, education level, occupation, oral hygiene habits, DMFT scores and dietary history; Babies' delivery type, birth weight, feeding type, oral hygiene practices, feeding habits, bottle usage, pacifier usage, consumption of sugary foods, were also recorded. The effect of factors related to both mothers and infants was examined comparatively. S.mutans DNA was detectable in 87% and LB DNA was detected in 37% mothers, while it was undetected in 63% mothers at the first sampling. S.mutans was detected in 37% and, while LB was detected in 5% of the newborns in the first 48 hours of their life. At the second sampling, the S.mutans and LB levels in infants have increased, while there has been no significant change in mothers. A significant relationship was found only between the increase in S.mutans in infants and the presence of erupted teeth. S.mutans and LB were able to colonize on the oral mucosal surfaces of edentulous newborns, with the counts of both bacteria increasing significantly with tooth eruption.

Enhancing smile and Altering Thrust using Modified Groper’s Appliance: A Case-Report

Early childhood caries, has a major influence on child’s lifestyle, resulting in child experiencing severe pain, premature loss of teeth, poor nutrition, difficulty chewing, speech, compromised esthetics, development of abnormal oral habits and delay in achieving normal growth and development of child. This paper presents a case report of a Four-year-old child diagnosed with Severe Early Childhood Caries. It explains treatment plan for rehabilitating child's mouth, including caries prevention and restorative procedures using appliances and making special adjustments to a child's feeding habits, combined with maintaining good oral hygiene practices. Early childhood caries is an important oral condition that requires prompt treatment and early intervention. Early diagnosis and awareness of ECC are essential for helping the child maintain a good quality of life.

Feeding habits of splendid alfonsino Beryx splendens in the vicinity of Kuroshio, the south of Japan

AbstractGut contents and nitrogen isotope ratio (δ15N) analyses were conducted on splendid alfonsino Beryx splendens collected in the vicinity of Kuroshio from May 2015 to November 2016 (n = 708) to identify their feeding habits in the Western North Pacific. Micronektonic fish, shrimp, and squid were the dominant prey species, with the Decapoda Acanthephyra quadrispinosa, Prehensilosergia prehensilis, Cephalopoda Enoploteuthis chunii, Chiroteuthis calyx, Teleostei Sigmops gracilis, and Gonostoma elongatum. These micronektons are common in the Kuroshio Current; thus, B. splendens is a possible opportunistic feeder. Gut content weight (GCW), occurrence (%O) of fish and squid, and δ15N were significantly increased with the fork length (FL) of B. splendens. Only the %O of shrimp does not show a significant relationship with the FL of B. splendens. These indicated the ontogenetic shift of dominant prey from shrimp to fish. Fattened specimens could also prey on a greater number of fish. The seasonality of GCW and %O values was high in spring and autumn and low in summer and winter. This seasonality indicated that the feeding habits of B. splendens are controlled by primary productivity in the surface layer and/or by maturity. When the Kuroshio flowed in the north of Hachijojima Island, the GCW was significantly increased, and some organisms, including C. calyx, G. elongatum, and S. gracilis, were preyed on more. While the offshore area of the Kuroshio has low productivity, B. splendens can actively prey in this area, indicating that it is an important feeding ground for this species.

Responsive feeding practices among Arabic and Mongolian speaking migrant mothers in Australia: A qualitative study.

Establishing healthy feeding habits during infancy is crucial for optimal growth. However, certain parental feeding and cultural practices might hinder the development of children's healthy eating behaviours. This research explored responsive feeding practices among migrant mothers in Australia. Semi-structured telephone interviews were conducted in their native language with 20 Arabic and 20 Mongolian-speaking migrant mothers with children under 2 years old or currently pregnant. Thematic analysis was conducted using the framework method. Both cultural groups followed a variety of feeding practices, including on demand responsive feeding or structured schedules. Arabic-speaking mothers tended to demonstrate responsive feeding practices more frequently than Mongolian-speaking mothers, except for those using formula feeding, who consistently followed a fixed feeding routine. When introducing solid foods, mothers from both groups often overlooked their babies' hunger and satiety cues, frequently pressuring their children to finish their entire plate. One cited reason for this was the challenge parents faced in identifying such cues. Arabic-speaking mothers often supplemented with formula top-ups after introducing solid foods, due to the belief that breast milk or solid foods alone might not sufficiently nourish their infants. Additionally, some Arabic-speaking mothers used food-based rewards to encourage eating. Mongolian mothers expressed a cultural preference for chubby babies, a potential reason why they may have been inclined to pressure-feed their children. Moreover, both groups reported using digital devices to distract their children during meals. This study highlights the necessity of tailoring future resources and services related to responsive feeding practices to accommodate diverse literacy levels and cultural backgrounds.

Microplastic pollution in aquafeed of diverse aquaculture animals

Microplastics have emerged as pervasive contaminants, and determining their occurrence in aquafeed is key for evaluating their risks to farmed animals and, by extension, humans. However, knowledge about microplastic in aquafeed is still limited. Herein, we determined microplastic characteristics in aquafeed for five important aquaculture animals with different feeding habits. Aquafeed samples were collected for spotted sea bass, shrimp, grass carp, Tilapia, and frogs from main companies in China. The samples were digested using chemical digestion, and the residuals were subjected to a density separation. Microplastics were identified under the microscope and characterized by their shape, color, size, and polymer type. The results showed that microplastics are highly abundant in the feed of frogs, followed by spotted sea bass, Tilapia, grass carp, and shrimp. We found that feed size contributes to the total microplastic abundance in the feed. Further, microplastics were mainly in microfiber form, and the dominant polymer type was propylene, suggesting that packaging and processing are the main sources of pollution. Additionally, the most abundant size of microplastics was 100–1000 μm. Calculating microplastic ingestion risk, the spotted sea bass had the greatest recorded risk of microplastic ingestion, followed by grass carp, frogs, Tilapia, and shrimp. This study lays a foundational step toward understanding microplastic effects on aquaculture animals and calls for further environmentally relevant laboratory experiments to assess the risk of microplastic ingestion on animals and potential transfer to humans.

Pest categorisation of non-EU Scolytinae on non-coniferous hosts.

The EFSA Panel on Plant Health performed a group pest categorisation for the EU territory of non-EU Scolytinae (Coleoptera: Curculionidae) on non-coniferous hosts, which total 6495 known species. Most species attack apparently healthy, weakened or dead trees, either feeding on the phloem ('bark beetles' subgroup) or on fungi inoculated into the sapwood ('ambrosia beetles' subgroup). Smaller subgroups feed and reproduce in seeds and fruits, or in herbaceous plants. Some species are polygynous, the males initiate a gallery or a chamber on or in a new host and attract females. Others are monogamous, and the females initiate the new galleries. Many species respond to primary volatile attractants emitted by the hosts, and some produce aggregation pheromones that attract conspecifics of both sexes. The species attacking living hosts are often associated with fungi that contribute to weakening the host defences and provide nutrients to the insects. Some are inbreeding; the males in the offspring mate with their sisters and rarely leave their natal tree. The larvae of all species develop and pupate within their hosts. Based on catalogues and other published data, a database was constructed providing information on hosts, feeding and reproductive habits, geographic distribution and the Köppen-Geiger climate types in countries where species occur. The Scolytinae were screened to exclude species in the following categories: (i) 708 species attacking conifers; (ii) 127 species present in at least four EU Member States and (iii) 440 species occurring in areas with climatic conditions not occurring in the EU. Among the remaining 5220 species, 88 species known for their mobility, occupying at least two landmasses separated by geographical barriers and some of which had impact levels documented in literature, were extracted. They were grouped into four subcategories: (i) 12 species with high impact on plant health; (ii) 16 species with low or doubtful impact; (iii) 48 species with no impact; (iv) 12 species with no impact and which had never been recorded as 'introduced' in the consulted catalogues but occurring on at least two landmasses. All 88 species could enter the EU with wood or wood products, or with plants for planting, and could establish because host plants are available, and climate is suitable in parts of the EU. Control measures to inhibit introduction are available. There is considerable uncertainty regarding the potential impact of many species. Methods for the reliable identification of many species are lacking. For some species of non-EU Scolytinae on non-coniferous hosts, all criteria assessed by EFSA for consideration as potential quarantine pest are met. Nevertheless, the Panel was not able to develop a method to discriminate confidently between species that clearly meet the criteria for potential quarantine pest status and those that do not.

USE OF THE ZOOLOGICAL INFORMATION MANAGEMENT SYSTEM (ZIMS) DATABASE (2003-2023) FOR EVALUATION OF PRACTITIONER-SELECTED MELOXICAM DOSES AND THE RELATIONSHIP TO AVIAN TAXONOMY.

Meloxicam, a commonly used NSAID, has wide variation in pharmacokinetics between different avian species. The present study hypothesized that meloxicam dosage regimens were similar within, but differ between, groups of avian species with similar feeding habits, habitats, or migratory behaviors. Utilizing the international Zoological Information Management System (ZIMS), drug usage extracts were compiled for meloxicam across eleven major orders of birds. The orders were selected based on their prevalence in zoological collections, wildlife rehabilitation centers, the pet trade, and production environments. Each species with a record available in drug usage extracts was classified into broad categories of main habitat, diet, and migratory status. Significant patterns associated with habitat, diet, or migratory status were not identified statistically. An inverse relationship was identified statistically between the practitioner mg/kg dose and body weight in kg in birds that weigh approximately 20 kg or greater. This study includes practitioner-reported summary data of current doses used in the veterinary field to treat many different avian species. Adverse effects of meloxicam were recorded in <5% of individuals evaluated at the species level in this study.

Differences between phytophagous and predatory species in Pentatomidae based on the mitochondrial genome.

Pentatomidae includes many species of significant economic value as plant pests and biological control agents. The feeding habits of Pentatomidae are closely related to their energy metabolism and ecological adaptations. In this study, we sequenced the mitochondrial genomes of 12 Asopinae species using the next-generation sequencing to explore the effect of dietary changes on mitochondrial genome evolution. Notably, all sequences were double-stranded circular DNA molecules containing 37 genes and one control region. We then compared and analyzed the mitochondrial genome characteristics of phytophagous and predatory bugs. Notably, no significant difference was observed in the length of the mitochondrial genomes between the predatory and phytophagous bugs. However, the AT content was higher in the mitochondrial genomes of phytophagous bugs than that of predatory bugs. Moreover, phytophagous bugs prefer codon usage patterns ending in A/T compared with predatory bugs. The evolution rate of predatory bugs was lower than that of phytophagous bugs. The phylogenetic relationships across phytophagous bugs' lineages were largely consistent at depth nodes based on different datasets and tree-reconstructing methods, and strongly supported the monophyly of predatory bugs. Additionally, the estimated divergence times indicated that Pentatomidae explosively radiated in the Early Cretaceous. Subsequently, the subfamily Asopinae and the genus Menida diverged in the Late Cretaceous. Our research results provide data supporting for the evolutionary patterns and classification of Pentatomidae.

Practices for introducing complementary foods in Taiwan: A nationwide survey from 2013 to 2016

Background/purposeIntroducing complementary foods to infants is a critical stage in their healthy growth and development process. In this study, we analyzed the feeding habits and choices of caregivers in Taiwan during this essential transition period. MethodsData from the 2013–2016 Nutrition and Health Survey in Taiwan were analyzed. Using a multistage stratified sampling technique, we collected data through questionnaires on the feeding practices, challenges, and information sources associated with complementary feeding. We also investigated the timing of introducing various foods. Certain feeding indicators recommended by the World Health Organization were modified and used for analysis. ResultsAmong 439 caregivers of infants aged 2–24 months, complementary feeding typically began at 5 months, and it primarily began with cereals and pureed foods. At 6–8 months of age, 98.29% of the infants received these foods. Only 48.39% of infants aged 6–24 months consumed eggs or flesh foods. Among the primary challenges for caregivers were concerns regarding infants’ adaptation to new foods (38.2%), refusal of foods by infants (37.1%), and uncertainty regarding which foods to introduce (11.4%). The main sources of information were friends and family (46.9%), the Internet (46.5%), and baby care books (35.6%). Notably, approximately 51% of the respondents used commercial baby foods. ConclusionIn Taiwan, although the majority of infants begin complementary feeding on time, the introduction of eggs and flesh foods is typically delayed. Given the growing reliance on the Internet in the modern age, accurate feeding information should be disseminated online.

Sustainable aquaculture of West African freshwater prawns Macrobrachium vollenhovenii (Herklots, 1857) and M. macrobrachion (Herklots, 1851) (Decapoda: Caridea: Palaemonidae)

Abstract The river prawn Macrobrachium vollenhovenii (Herklots, 1857) and the brackish river prawn M. macrobrachion (Herklots, 1851) are economically and ecologically significant West African species. Recent molecular studies suggest they might be different ecotypes of the same species, complicating taxonomy and sustainable aquaculture practices. Both species face significant threats from human exploitation, leading to high exploitation rates and smaller average sizes within populations. Seasonal variations affect their abundance, with M. macrobrachion more prevalent during the rainy season and M. vollenhovenii thriving in the dry season. Their omnivorous detritivorous feeding habits involve consuming detritus, diatoms, phytoplankton, and insect larvae during juvenile stages. Aquaculture of M. vollenhovenii and M. macrobrachion encounters difficulties such as limited hatchery technology and low larval survival rates. Efforts to cultivate juveniles or adults in captivity face obstacles like high mortality rates due to moulting stress, handling, feeding, and cannibalism. Reintroducing captive-bred prawns into the wild offers dual benefits: controlling snail populations that host parasite causing schistosomiasis and restoring ecological balance while enhancing local fisheries and providing socio-economic benefits. To achieve sustainable aquaculture, it is crucial to address taxonomic complexities, implement management measures to mitigate overexploitation, improve hatchery technology, optimise feeding strategies, reduce stress during moulting and handling, and engage local communities through capacity building and awareness programs. This review aims to contribute to a better understanding of these prawns, promoting informed decision-making for sustainable management, conservation, and socio-economic benefits in West Africa.

Mercury contamination and potential health risk to French seabirds: A multi-species and multi-site study

Mercury (Hg) is a naturally occurring highly toxic element which circulation in ecosystems has been intensified by human activities. Hg is widely distributed, and marine environments act as its main final sink. Seabirds are relevant bioindicators of marine pollution and chicks are particularly suitable for biomonitoring pollutants as they reflect contamination at short spatiotemporal scales. This study aims to quantify blood Hg contamination and identify its drivers (trophic ecology inferred from stable isotopes of carbon (δ13C) and nitrogen (δ15N), geographical location, chick age and species) in chicks of eight seabird species from 32 French sites representing four marine subregions: the English Channel and the North Sea, the Celtic Sea, the Bay of Biscay and the Western Mediterranean. Hg concentrations in blood ranged from 0.04 μg g−1 dry weight (dw) in herring gulls to 6.15 μg g−1 dw in great black-backed gulls. Trophic position (δ15N values) was the main driver of interspecific differences, with species at higher trophic positions showing higher Hg concentrations. Feeding habitat (δ13C values) also contributed to variation in Hg contamination, with higher concentrations in generalist species relying on pelagic habitats. Conversely, colony location was a weak contributor, suggesting a relatively uniform Hg contamination along the French coastline. Most seabirds exhibited low Hg concentrations, with 74% of individuals categorized as no risk, and < 0.5% at moderate risk, according to toxicity thresholds. However, recent work has shown physiological and fitness impairments in seabirds bearing Hg burdens considered to be safe, calling for precautional use of toxicity thresholds, and for studies that evaluate the impact of Hg on chick development.

Thermal regime of High Arctic tundra ponds, Nanuit Itillinga (Polar Bear Pass), Nunavut, Canada

Abstract. This study evaluates the seasonal and inter-seasonal temperature regime of small tundra ponds ubiquitous to an extensive, low-gradient wetland in the Canadian High Arctic. Pond temperatures can modify evaporation and ground thaw rates, impact losses of greenhouse gases, and control the timing and emergence of insects and larvae critical for migratory-bird feeding habits. We focus our study on thaw ponds with a range of hydrologic linkages and sizes across Nanuit Itillinga, formerly known as Polar Bear Pass (PBP), Bathurst Island, and compare their thermal signals to other Arctic ponds. Pond temperatures and water levels were evaluated using temperature and water level loggers and verified by regular manual measurements. Other environmental data collected included microclimate, frost table depths, and water conductivity. Our results show that there is much variability in pond thermal regimes over seasons, years, and space. Cumulative relative pond temperatures were similar across years, with ponds normally reaching 10–15 °C for short to longer periods, except in 2013, which experienced a cold summer season during which pond temperatures never exceeded 5 °C. Pond frost tables and water conductivities respond to variable substrate conditions and pond thermal patterns. This study contributes to the ongoing discussion on climate warming and its impact on Arctic landscapes.

Preying on cyprinid snout warts (pearl organs) as a novel and peculiar habit in the Lake Malawi cichlid Docimodus evelynae

Cichlid fishes in the African Great Lakes have undergone explosive speciation, acquiring markedly varying ecologies and diets. There are multiple lineages of scale-eating cichlids, and their natural history and evolutionary ecology is only partially understood. We examined the feeding habit of Docimodus evelynae, a known scale eater, in Lake Malawi. The stomach contents of young individuals mainly consisted of unknown 1 mm hard, white warts (> 30%). To clarify the origin of these warts, we conducted an X-ray fluorometer analysis, and found they were rich in sulphur but low in silicon and calcium, suggesting they were epidermal tissues. Histological and morphological analyses revealed they were multicellular and cup-shaped. These characteristics matched only those of the pearl organs of the coexisting cyprinid Labeo cylindricus. DNA was extracted from the warts found in the stomach of five D. evelynae individuals, followed by PCR using primers targeting the partial COI gene of L. cylindricus. The resulting sequences exhibited 98% similarity to those of L. cylindricus. Pearl organs, never reported as a primary food for fish, could offer a substantial nutritional source based on calorific calculations. Understanding how this peculiar diet is foraged is essential for full comprehension of the food-web structure in this lake.