Habitat Switch and Niche Overlap in Coregonid Fishes: Effects of Zooplankton Abundance

1991 ◽  
Vol 48 (12) ◽  
pp. 2307-2315 ◽  
Author(s):  
T. F. Næsje ◽  
B. Jonsson ◽  
O. T. Sandlund ◽  
G. Kjellberg
Keyword(s):  
Time Lag ◽  
Niche Overlap ◽  
Pelagic Zone ◽  
Coregonus Lavaretus ◽  
Zooplankton Abundance ◽  
Important Prey ◽  
Pelagic Habitat ◽  
Limnocalanus Macrurus ◽  
Large Copepod ◽  
Coregonid Fishes

Vendace (Coregortus albula) in Lake Mjøsa lived in the pelagic zone and gillnet catches were correlated with water temperature (r2 = 0.457, p < 0.005). Whitefish (Coregonus lavaretus) exploited both epibenthic and pelagic areas. Whitefish with body lengths between 25 and 35 cm moved from the epibenthic to pelagic zone during summer; other length groups remained in epibenthic habitats. The pelagic fish returned to epibenthic areas in the autumn. Cladocerans were important food items for both fish species in the pelagic zone. The large copepod Limnocalanus macrurus was eaten only by vendace whereas surface insects were more important prey for whitefish. This suggests that vendace is the more specialized zooplanktivore. The pelagic gillnet catch of whitefish and the pelagic habitat overlap between whitefish and vendace increased with increasing zooplankton densities at depths between 0 and 50 m (r2 = 0.609 and 0.494, respectively, p < 0.01). During spring and autumn we observed a time lag between the change in zooplankton abundance and habitat switches of whitefish. The fish moved to the more profitable habitat several days after food availability had changed, indicating an element of learning in choice of habitat.

scholarly journals Diet and trophic niche overlap of Boana bischoffi and Boana marginata (Anura: Hylidae) in southern Brazil

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Camila F. Moser ◽  
Mateus de Oliveira ◽  
Fernanda R. de Avila ◽  
Diogo Dutra-Araújo ◽  
Renata K. Farina ◽  
...  
Keyword(s):  
Natural History ◽  
Atlantic Forest ◽  
Diet Composition ◽  
Niche Breadth ◽  
Niche Overlap ◽  
Food Composition ◽  
Trophic Niche ◽  
Southern Brazil ◽  
Important Prey ◽  
History Of

Abstract: The species Boana bischoffi and Boana marginata are endemic to the Atlantic Forest, where they often occur in sympatry. There is a large gap in the knowledge of natural history of both species. In this study, we aimed to describe and compare the diet composition of B. bischoffi and B. marginata in the southern domain of the Brazilian Atlantic Forest. We analyzed the gastrointestinal contents of 43 individuals of B. bischoffi and 30 individuals of B. marginata. Both showed a high trophic niche overlap (0.90 Ojk). The most important prey categories for both species belonged to the orders Araneae and Coleoptera. The species niche breadth (Bsta) varied from 0.35 to 0.42, suggesting a generalist feeding behavior for both species. Our data provide unprecedented information on these species' food composition, contributing to a better knowledge of the natural history of neotropical anurans.

scholarly journals Sexual dimorphism, diet, and notes on reproduction in Oxyrhopus trigeminus (Serpentes: Colubridae) in the semiarid Caatinga of northeastern Brazil

2019 ◽  
Vol 18 (1) ◽  
pp. 89-96
Author(s):  
Rafael Damasceno Fernandes Coelho ◽  
Raul Fernandes Dantas Sales ◽  
Leonardo Barros Ribeiro
Keyword(s):  
Sexual Dimorphism ◽  
Prey Species ◽  
Niche Overlap ◽  
Morphological Characters ◽  
Northeastern Brazil ◽  
Minimum Size ◽  
Important Prey ◽  
Body Sizes ◽  
Dietary Niche ◽  
Males And Females

Sexual dimorphism, diet, and notes on reproduction in Oxyrhopus trigeminus (Serpentes: Colubridae) in the semiarid Caatinga of northeastern Brazil. Selected morphological characters, diet, and reproduction of the false-coral snake, Oxyrhopus trigeminus, from several localities in the Caatinga region of northeastern Brazil are described based on examination of preserved specimens. Sexual dimorphism is evident, with females attaining larger body sizes than males, but males have relatively larger heads and tails. A total of 25 prey items was identifed in 23 of the 97 O. trigeminus examined; based on the orientation of the prey in the stomachs, all items were ingested headfrst. Lizards are the most frequent prey (96%) of O. trigeminus, with the lizard Tropidurus hispidus being the most important prey species both in number and in volume; marsupials account for 4% of the diet. Juveniles have a narrower dietary niche width than adults, presumably because they have smaller mouths with a narrower gape. Females have a wider dietary niche than males, but there is a high niche overlap between the sexes; males and females do not differ in prey volumes. The analysis of the gonads showed that 10 females have 4–13 vitellogenic follicles (mean 7.8 ± 2.8 follicles), and 2 females have oviducal eggs, one with only one egg and the other with fve eggs. The estimated minimum size at maturity for female O. trigeminus in the Caatinga is 400 mm.

scholarly journals Unusual vertical distribution of zooplankton and fish in the pelagic zone of Lake Sevan during summer stratification

2021 ◽  
Vol 4 (3) ◽  
pp. 27-41
Author(s):  
Mikhail I. Malin ◽  
Svetlana M. Zhdanova ◽  
Dmitriy B. Kosolapov ◽  
Inga P. Malina ◽  
Natalya G. Kosolapova ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Vertical Distribution ◽  
Water Temperature ◽  
Lower Boundary ◽  
Fish Population ◽  
Coregonus Lavaretus ◽  
Zooplankton Abundance ◽  
Night Time ◽  
Lake Sevan ◽  
Oxygen Concentrations

Previous studies in Lake Sevan during summer stratification have shown that the highest zooplankton abundance and biomass was found at the lower boundary of the epilimnion. At the same time, whitefish (Coregonus lavaretus), being main planktivorous species in the lake, preferred the hypolimnion, but was leaving this layer if dissolved oxygen concentrations decreased to 1–5 mg/L. The study was conducted in Bolshoy Sevan (the southern part of Lake Sevan) on July 29–30, 2019. The vertical profiles of water temperature and dissolved oxygen concentration, as well as distribution of major taxonomic groups of aquatic organisms were assessed four times a day: in the dark (night time), in the light (day time), and in twilight (morning and evening). Fish population density was assessed using a “Simrad EK80” echosounder. Vertical distribution of zooplankton and fish observed within the study period did not correspond to that described earlier. Maximal zooplankton biomass during the study was recorded in the hypolimnion, and minimal biomass, in the epilimnion. Most of fish (89–100%) located in the metalimnion. At night, about 10% of the fish population descended to the hypolimnion, despite the low dissolved oxygen concentrations found there (3.0–3.1 mg/L). At dawn, about 7% of the fish ascended to the epilimnion, reaching a 7-m depth, where the water temperature was 20.8 °C. The water temperature range preferred by most fish individuals varied during the observation period and did not correspond to previously reported ranges.

Food habits of Brazilian boid snakes: overview and new data, with special reference to Corallus hortulanus

2009 ◽  
Vol 30 (4) ◽  
pp. 533-544 ◽  
Author(s):  
Lígia Pizzatto ◽  
Otavio Marques ◽  
Kátia Facure
Keyword(s):  
Literature Review ◽  
Food Habits ◽  
Prey Size ◽  
Niche Overlap ◽  
Sympatric Species ◽  
Geographic Range ◽  
Gut Contents ◽  
Museum Specimens ◽  
Important Prey ◽  
Prey Items

AbstractThis study examines the diet of eight boid snakes: Boa c. constrictor, Boa c. amarali, Corallus caninus, C. hortulanus, Epicrates cenchria, E. crassus, E. assisi and Eunectes murinus mainly by analyzing the gut contents of preserved museum specimens, and includes a literature review to present an overview of the diet of Brazilian boids. Mammals constitute the primary prey consumed by the majority of the species. Birds are also frequently consumed by C. hortulanus and Boa contrictor, and are the most important prey for B. c. amarali. Ectotherms (mostly lizards) were only consumed by immature snakes. Such prey is rarely consumed by B. c. amarali and not recorded for Epicrates and Eunectes species in our dissections. C. caninus is likely a mammal specialist and Epicrates prey on birds more opportunistically. The niche overlap index varied from 0.27-0.52 for species occurring in the same bioma and geographic range but it is possible this overlap is lower as most sympatric species explore different macrohabitat. C. hortulanus exhibited a significant relationship between prey size and predator head size; this relationship did not differ among mature and immature snakes. In comparison to immature individuals heavier adult snakes fed on heavier prey items however, the ratio between prey/predator mass decreased with increase in predator mass (or size). Most boids exploit diurnal and nocturnal preys, probably using both sit-and-wait and active tactics. They feed on the ground but boas and C. hortulanus and possibly E. cenchria also exploit arboreal prey.

scholarly journals Autecology of the lizard Colobosauroides cearensis (Squamata: Gymnophthalmidae) from Brazilian semiarid Caatinga

2019 ◽  
Vol 18 (2) ◽  
pp. 209-223
Author(s):  
Aldenir Ferreira da Silva Neta ◽  
Cicera Silvilene Leite Matias ◽  
Robson Waldemar Ávila
Keyword(s):  
Domain Knowledge ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Microhabitat Use ◽  
Prey Category ◽  
Important Prey ◽  
Brazilian Semiarid ◽  
History Of ◽  
Gravid Females ◽  
Average Body

Autecology of the lizard Colobosauroides cearensis (Squamata: Gymnophthalmidae) from Brazilian semiarid Caatinga. Colobosauroides cearensis is a diurnal lizard with a relictual distribution associated with forested habitats in the Brazilian Caatinga Domain. Knowledge of the natural history of this secretive lizard is scarce. Herein, the diet, reproduction, sexual dimorphism, microhabitat use, and thermal ecology of C. cearensis are described based on feldwork in 2015–2017 in the state of Ceará, Brazil. The diet of the lizards is composed exclusively of arthropods, with Formicidae being the most important prey category. Numerical and volumetric niche breadths are 5.52 and 9.2 respectively, and trophic niche overlap between females and males is 0.3. Males are distinguished from females by the larger size of the males and the presence of femoral pores. Colobosauroides cearensis is cryptozoic, inhabiting the leaf litter and having no direct contact with the soil or solar radiation. The average body temperature of the lizards is 30.4 ± 3.3°C, which is positively correlated with the air temperature. Gravid females with fxed clutch size of two eggs are found in early rainy season. Oviposition occurs between April and May (when the highest number of juveniles are observed). Sexual maturity occurs early in males and testicular volume is signifcantly correlated with body size.

scholarly journals Changes in prey importance and prey niche overlap of sexes during the alpine newt breeding season

2020 ◽  
Vol 146 (2) ◽  
Author(s):  
Oldřich Kopecký
Keyword(s):  
Breeding Season ◽  
Stomach Contents ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Sexual Differences ◽  
Food Sources ◽  
Quantitative Composition ◽  
Important Prey ◽  
Alpine Newt ◽  
Prey Items

Urodeles, including European newts, are usually sexually dimorphic predators. Among newts, the alpine newt has the most pronounced sexual size dimorphism (in favour of females). Gender is a factor that is often associated with intra-specific diet differences. Despite the significant number of dietary studies on the alpine newt, some topics such as the breadth of the trophic niche and its overlap between sexes, or inter-sexual differences in qualitative and quantitative composition of prey remain unresolved. The present study dealing with these questions was conducted at two localities (ponds at an elevation of about 450 m) in the Czech Republic. Newts were captured from the banks during the entire breeding season using a dip net, and the stomach contents were extracted using a stomach flushing technique. Altogether 190 individuals were sampled, and a total of 1,417 prey items were obtained. The available food sources differed over the course of the breeding season, as newts changed the taxa they preyed on. This reflects the ability of newts to switch between several hunting strategies. The overall food niche overlap between the sexes was relatively large (C = 0.761, resp. C = 0.797). Inter-sexual differences were detected at both localities, mainly in the number of prey items consumed from the most important prey categories such as Rana eggs or Isopoda, which were consumed in higher numbers by females. The findings of this study suggest that females are more sensitive to the trade-off between energy intake and expenditure during the breeding season.

scholarly journals Ribosomal genes in Coregonid fishes (Coregonus lavaretus, C. albula and C. peled) (Salmonidae): single and multiple nucleolus organizer regions

Heredity ◽  
2001 ◽  
Vol 87 (6) ◽  
pp. 672-679 ◽  
Author(s):  
Malgorzata Jankun ◽  
Paulino Martinez ◽  
Belen G Pardo ◽  
Lech Kirtiklis ◽  
Petr Rab ◽  
...  
Keyword(s):  
Ribosomal Genes ◽  
Nucleolus Organizer ◽  
Coregonus Lavaretus ◽  
Nucleolus Organizer Regions ◽  
Coregonid Fishes

Cross-Lagged Relationships Between Self-Esteem, Self-Construal, and Happiness in a Three-Wave Longitudinal Study

2019 ◽  
Vol 40 (3) ◽  
pp. 177-185
Author(s):  
Daniela Moza ◽  
Laurențiu Maricuțoiu ◽  
Alin Gavreliuc
Keyword(s):  
Structural Equation ◽  
Time Lag ◽  
Self Esteem ◽  
Equation Modeling ◽  
Future Research ◽  
Cross Sectional ◽  
Self Construal ◽  
Self Worth ◽  
Practical Implications ◽  
Independent Person

Abstract. Previous research established that an independent construal of the self is associated with higher self-esteem, which, in turn, is associated with increased happiness. Regarding the directionality of these relationships, theoretical arguments have suggested that self-construal precedes self-esteem and that self-esteem precedes happiness. However, most research in this area is cross-sectional, thus limiting any conclusions about directionality. The present study tested these relationships in 101 Romanian undergraduates using a 3-wave cross-lagged design with a 6-month time lag between every two waves. Structural equation modeling analyses revealed that self-esteem is an antecedent of both happiness and dimensions of independent self-construal (i.e., consistency vs. variability and self-expression vs. harmony). In other words, one’s positive evaluation of self-worth precedes one’s self-perception as being a happy and independent person. The findings are discussed with respect to the theoretical and practical implications, along with limitations and suggestions for future research.

Relationships Between Bidirectional Work-Family Interactions and Psychological Well-Being

2014 ◽  
Vol 13 (2) ◽  
pp. 87-96 ◽  
Author(s):  
Xi-Chao Zhang ◽  
Oi Ling Siu ◽  
Jing Hu ◽  
Weiwei Zhang
Keyword(s):  
Family Conflict ◽  
Structural Equation ◽  
Time Lag ◽  
Well Being ◽  
Equation Modeling ◽  
Family Interactions ◽  
Work Family Conflict ◽  
Psychological Well Being ◽  
Direct Model ◽  
Work Family

This study investigated the direct, reversed, and reciprocal relationships between bidirectional work-family conflict/work-family facilitation and psychological well-being (PWB). We administered a three-wave questionnaire survey to 260 married Chinese employees using a time lag of one month. Cross-lagged structural equation modeling analysis was conducted and demonstrated that the direct model was better than the reversed causal or the reciprocal model. Specifically, work-to-family conflict at Time 1 negatively predicted PWB at Time 2, and work-to-family conflict at Time 2 negatively predicted PWB at Time 3; further, work-to-family facilitation at Time 1 positively predicted PWB at Time 2. In addition, family-to-work facilitation at Time 1 positively predicted PWB at Time 2, and family-to-work conflict at Time 2 negatively predicted PWB at Time 3.

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