Seasonal feeding plasticity can facilitate coexistence of dominant omnivores in Neotropical streams

AbstractCoexistence of ecomorphologically similar species in diverse Neotropical ecosystems has been a focus of long-term debate among ecologists and evolutionary biologists. Such coexistence can be promoted by trophic plasticity and seasonal changes in omnivorous feeding. We combined stomach content and stable isotope analyses to determine how seasonal variation in resource availability influences the consumption and assimilation of resources by two syntopic fish species, Psalidodon aff. gymnodontus and P. bifasciatus, in the Lower Iguaçu basin. We also tested the impact of seasonality on trophic niche breadth and diet overlap of these two dominant omnivores. Seasonal changes in resource availability strongly influenced the consumption and assimilation of resources by the two fish species. Both species exhibited high levels of omnivory, characterized by high diversity of allochthonous resources in the wet season. Terrestrial invertebrates were the main component of diet during this season. However, in the dry season, both species reduced their isotopic niches, indicating diet specialization. High diet overlap was observed in both seasons, but the isotopic niche overlap was smaller in the dry season. Substantial reduction in the isotopic niche of P. bifascistus and a shift toward aquatic invertebrates can facilitate coexistence during this season of resource shortage. Feeding plasticity allows omnivorous fish to adjust their trophic niches according to seasonality, promoting the exploitation of different resources during periods of greater resource diversity. This seasonal variation could be an important mechanism that contributes to the resource partitioning and coexistence of dominant omnivores in Neotropical streams.

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Seasonal changes in water quality and macrophytes and the impact of cattle on tropical floodplain waterholes

Marine and Freshwater Research ◽

10.1071/mf12114 ◽

2012 ◽

Vol 63 (9) ◽

pp. 788 ◽

Cited By ~ 17

Author(s):

N. E. Pettit ◽

T. D. Jardine ◽

S. K. Hamilton ◽

V. Sinnamon ◽

D. Valdez ◽

...

Keyword(s):

Water Quality ◽

Seasonal Changes ◽

Aquatic Macrophyte ◽

Plant Cover ◽

Critical Role ◽

Dry Season ◽

Nutrient Concentrations ◽

Wet Season ◽

Dry Tropics ◽

The Impact

The present study indicates the critical role of hydrologic connectivity in floodplain waterholes in the wet–dry tropics of northern Australia. These waterbodies provide dry-season refugia for plants and animals, are a hotspot of productivity, and are a critical part in the subsistence economy of many remote Aboriginal communities. We examined seasonal changes in water quality and aquatic plant cover of floodplain waterholes, and related changes to variation of waterhole depth and visitation by livestock. The waterholes showed declining water quality through the dry season, which was exacerbated by more frequent cattle usage as conditions became progressively drier, which also increased turbidity and nutrient concentrations. Aquatic macrophyte biomass was highest in the early dry season, and declined as the dry season progressed. Remaining macrophytes were flushed out by the first wet-season flows, although they quickly re-establish later during the wet season. Waterholes of greater depth were more resistant to the effects of cattle disturbance, and seasonal flushing of the waterholes with wet-season flooding homogenised the water quality and increased plant cover of previously disparate waterholes. Therefore, maintaining high levels of connectivity between the river and its floodplain is vital for the persistence of these waterholes.

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Patterns of Fish Assemblage, Growth, and Diet Composition in a Tropical River between Two Cascading Hydropower Dams

International Journal of Ecology ◽

10.1155/2021/6652782 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Lee Nyanti ◽

Chen-Lin Soo ◽

Afina-Yian Chundi ◽

Elsa-Cordelia-Durie Lambat ◽

Alvinna Tram ◽

...

Keyword(s):

Fish Species ◽

Diet Composition ◽

Fish Assemblages ◽

Condition Factor ◽

Dry Season ◽

Growth Patterns ◽

Native Fish ◽

Wet Season ◽

Fish Samples ◽

The Impact

Construction of cascade dams has been shown to have impacts on fish assemblages and biodiversity. Yet, there is no literature on fish assemblages in the Murum River that connects the cascading Bakun and Murum dams in Sarawak, Malaysia. Hence, study on this modified ecosystem is necessitated to better understand the effects of the cascade dam construction on fish fauna. For this, fish samples were caught at five stations located along the river during both dry and wet seasons. Environmental parameters were taken concurrently with fish sampling. Length-weight relationship, condition factors, and diet composition of selected fish species in the river were also determined. The present study demonstrated that there are indications of the impact of cascading dams on the formation of a complex ecosystem in the Murum River, that is, changing from the shallow downstream of the Murum Dam to the deep transitional and inundated zone of the Bakun reservoir. The transitional zone in the Murum River exhibited the lowest fish species diversity, richness, and evenness during the dry season due to low pH and DO coupled with high turbidity. The biological indices improved when the water quality improved during the wet season. On the contrary, the diversity and evenness indices at the inundated tributary station decreased remarkably during the wet season, likely due to the migration of fish during the onset of the rainy season. This study showed that Barbonymus schwanenfeldii has a wider feeding habit which contributes to its higher distribution and abundance in the Murum River. The growth patterns of B. schwanenfeldii, Cyclocheilichthys apogon, Hampala macrolepidota, Lobocheilos ovalis, and Osteochilus enneaporos were better during wet than dry season. Overall, the condition factor of all native fish species in the Murum River was in poor to fair condition, whereas the exotic species, Oreochromis mossambicus, exhibited excellent condition (K value > 2) for both seasons. The increase in the number of O. mossambicus coupled with its high condition factor indicates biological intrusion and a potential threat to the native fish species in the Murum River. Continuous monitoring is essential to detect in-time risk issues associated with environmental degradation and biological invasion in this regulated and inundated river ecosystem.

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Diet of two syntopic species of Crenuchidae (Ostariophysi: Characiformes) in an Amazonian rocky stream

Biota Neotropica ◽

10.1590/1676-0611-bn-2016-0281 ◽

2017 ◽

Vol 17 (1) ◽

Cited By ~ 1

Author(s):

Suzanne Fernandes ◽

Rafael Pereira Leitão ◽

Eurizângela Pereira Dary ◽

Ana Isabel Camacho Guerreiro ◽

Jansen Zuanon ◽

...

Keyword(s):

Fish Species ◽

Stomach Contents ◽

Relative Volume ◽

Diet Overlap ◽

Frequency Of Occurrence ◽

Food Items ◽

Taxonomic Level ◽

Genus Level ◽

The Family ◽

Feeding Plasticity

Abstract This study assessed the diet of two poorly known syntopic fish species of the family Crenuchidae, Characidium aff. declivirostre and Leptocharacidium omospilus, in a Presidente Figueiredo´ rocky stream, Amazonas, Brazil. The stomach contents were analyzed and their Frequency of Occurrence (FO %) and Relative Volume (Vol %) were combined in a Feeding Index (IAi). We examined 20 individuals of C. aff. declivirostre and 23 of L. omospilus. The Morisita-Horn Index was used to estimate the overlap between the diets of these species. Immature insects were the most valuable items consumed by both fish species. The diet of C. aff. declivirostre was mainly composed of larvae and pupae of Chironomidae, while L. omospilus predominantly consumed larvae of Hydroptilidae, Hydropyschidae and Pyralidae. Thus, both species were classified as autochthonous insectivorous. Characidium aff. declivirostre was considered a more specialized species, probably reflecting lower feeding plasticity or the use of more restricted microhabitats compared to L. omospilus. When the food items were analyzed at the family taxonomic level, the diet overlap between these species was considered moderate (Morisita-Horn Index = 0.4). However, a more thorough analysis, at the genus level, indicates a very low diet overlap. Therefore, we conclude that the feeding segregation between C. aff. declivirostre and L. omospilus may favor their co-existence, despite their high phylogenetic closeness.

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Seasonal Changes in Vitamin D Status and Bone Turnover in Healthy Irish Postmenopausal Women

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831.77.5.320 ◽

2007 ◽

Vol 77 (5) ◽

pp. 320-325 ◽

Cited By ~ 19

Author(s):

Hill ◽

McCarthy ◽

Jakobsen ◽

Lamberg-Allardt ◽

Kiely ◽

...

Keyword(s):

Vitamin D ◽

Seasonal Variation ◽

Bone Turnover ◽

Postmenopausal Women ◽

Seasonal Changes ◽

Late Summer ◽

Late Winter ◽

Vitamin D Status ◽

Old Irish ◽

The Impact

Objectives: To examine the effect of season on biochemical markers of bone turnover in 51-to 75-year-old Irish women and to investigate whether such changes are related to vitamin D status. Design: Longitudinal observational study. Setting: Cork, Ireland (52ºN). Subjects: 76 apparently healthy, free-living postmenopausal women (aged 51–75 years), not taking any medication and free from any condition likely to affect vitamin D status or calcium/bone metabolism. Results: Serum 25-hydroxyvitamin D [S-25(OH)D] showed a clear seasonal variation with significantly higher (p < 0.001) values during late summer than late winter. Both urinary pyridinoline (Ur-Pyr) (p < 0.01) and deoxypyridinoline (Ur-Dpyr) (p < 0.001), but not serum parathyroid hormone or osteocalcin, showed a marked seasonal variation with lowest values during late-summer. Stratifying women into those with S-25(OH)D levels ≥ or < 50 nmol/L (vitamin D adequate and inadequate, respectively) during late-winter, showed that Ur-Pyr and Ur-Dpyr in both groups were significantly (p < 0.05) lower during late summer, and the magnitude of the reduction from winter to summer was similar in both groups. Conclusion: Seasonal changes in bone resorption markers appeared to be linked to seasonal changes in vitamin D status. Further research is needed to investigate the impact of these changes on risk of bone loss and fracture.

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Composition and seasonal variation of the ichthyofauna from upper Rio Paraguaçu (Chapada Diamantina, Bahia, Brazil)

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132007000400012 ◽

2007 ◽

Vol 50 (4) ◽

pp. 663-672 ◽

Cited By ~ 8

Author(s):

Alexandre Clistenes de Alcântara Santos ◽

Érica Pellegrini Caramaschi

Keyword(s):

Seasonal Variation ◽

Seasonal Changes ◽

Rainy Season ◽

Multivariate Analyses ◽

Dry Season ◽

The Other ◽

Chapada Diamantina ◽

Number Of Species ◽

Abiotic Variables

The aim of this work was to characterize the composition of the ichthyofauna of the upper course of the Rio Paraguaçu. Two excursions were carried out, one in the dry season, and the other in the rainy season, with 36 localities sampled. A total of 63 species were collected. Multivariate analyses indicated that abiotic variables such as the channel order and altitude were the main influences on the number of species present. The number of species in each excursion was equivalent in the two seasons, suggesting that seasonal changes have little influence on the ichthyofauna of this area.

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ANALYSIS OF THE IMPACT OF VEGETATION DISTRIBUTION, URBANIZATION, AND SOLAR RADIATION ON THE SEASONAL VARIATION OF THE URBAN HEAT ISLAND EFFECT IN CEBU CITY USING LANDSAT AND GLOBAL HORIZONTAL IRRADIANCE DATA

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-4-w19-93-2019 ◽

2019 ◽

Vol XLII-4/W19 ◽

pp. 93-100

Author(s):

S. F. Cañete ◽

L. L. Schaap ◽

R. Andales ◽

R. E. S. Otadoy ◽

A. C. Blanco ◽

...

Keyword(s):

Seasonal Variation ◽

Solar Radiation ◽

Urban Heat Island ◽

Land Surface ◽

Dry Season ◽

Heat Island ◽

Hot Dry Season ◽

Urban Heat ◽

The Impact ◽

Cool Dry Season

Abstract. The Urban Heat Island (UHI) phenomenon is a manifestation of the abnormal amount of heat generated in urban areas and anthropogenic land surface modifications. While urbanization can improve material comfort and be a boon to the economy, the accompanying problems associated with urbanization like the UHI effect has implications on health, demand for water and energy, and impacts the microclimate. Land surface temperature (LST), the Normalized Difference Vegetation Index (NDVI), and the Normalized Difference Built-up Index (NDBI) were calculated from historical remotely-sensed Landsat data from 2013 to present. The global horizontal irradiance (GHI) was computed from the lidar-derived elevation model of Cebu City using the Geographical Resources Analysis Support System (GRASS). It is shown that annual variation in average temperatures in Cebu is generally less than 5 °C. Mean UHI temperatures in Cebu City do not show a clear trend over time, but categorizing data by season, namely the rainy season (June–November), the cool dry season (December–February), and the hot dry season (March–May), permits the emergence of a pattern. Surface temperatures for the cool dry season and hot dry season show a linearly increasing trend with R2 values of 0.916 and 0.514, respectively. This study further investigates the temporal change in the degree and extent of the UHI in Cebu City by analyzing LST maps. Regression analysis is done to determine how LST is affected by the distribution of vegetation (NDVI) and built-up (NDBI), and the seasonal variation in solar radiation through the GHI.

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Measuring Impact of Stress in Sandwich Generation Caring for Demented Parents

GeroPsych ◽

10.1024/1662-9647/a000114 ◽

2014 ◽

Vol 27 (4) ◽

pp. 171-179 ◽

Cited By ~ 6

Author(s):

Laurence M. Solberg ◽

Lauren B. Solberg ◽

Emily N. Peterson

Keyword(s):

Factor Analysis ◽

Exploratory Factor Analysis ◽

Social Worker ◽

Resource Availability ◽

Well Being ◽

Sandwich Generation ◽

Item Questionnaire ◽

Significant Difference ◽

Adult Caregivers ◽

The Impact

Stress in caregivers may affect the healthcare recipients receive. We examined the impact of stress experienced by 45 adult caregivers of their elderly demented parents. The participants completed a 32-item questionnaire about the impact of experienced stress. The questionnaire also asked about interventions that might help to reduce the impact of stress. After exploratory factor analysis, we reduced the 32-item questionnaire to 13 items. Results indicated that caregivers experienced stress, anxiety, and sadness. Also, emotional, but not financial or professional, well-being was significantly impacted. There was no significant difference between the impact of caregiver stress on members from the sandwich generation and those from the nonsandwich generation. Meeting with a social worker for resource availability was identified most frequently as a potentially helpful intervention for coping with the impact of stress.

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The seasonal changes of the gut microbiome of the population living in traditional lifestyles are represented by characteristic species-level and functional-level SNP enrichment patterns

BMC Genomics ◽

10.1186/s12864-021-07372-0 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Xue Zhu ◽

Jiyue Qin ◽

Chongyang Tan ◽

Kang Ning

Keyword(s):

Gut Microbiome ◽

Seasonal Changes ◽

Dry Season ◽

Urban Setting ◽

Snp Analysis ◽

Wet Season ◽

Human Gut ◽

Human Gut Microbiome ◽

Genome Level ◽

Prevalent Species

Abstract Background Most studies investigating human gut microbiome dynamics are conducted on humans living in an urban setting. However, few studies have researched the gut microbiome of the populations living traditional lifestyles. These understudied populations are arguably better subjects in answering human-gut microbiome evolution because of their lower exposure to antibiotics and higher dependence on natural resources. Hadza hunter-gatherers in Tanzania have exhibited high biodiversity and seasonal patterns in their gut microbiome composition at the family level, where some taxa disappear in one season and reappear later. Such seasonal changes have been profiled, but the nucleotide changes remain unexplored at the genome level. Thus, it is still elusive how microbial communities change with seasonal changes at the genome level. Results In this study, we performed a strain-level single nucleotide polymorphism (SNP) analysis on 40 Hadza fecal metagenome samples spanning three seasons. With more SNP presented in the wet season, eight prevalent species have significant SNP enrichment with the increasing number of SNP calling by VarScan2, among which only three species have relatively high abundances. Eighty-three genes have the most SNP distributions between the wet season and dry season. Many of these genes are derived from Ruminococcus obeum, and mainly participated in metabolic pathways including carbon metabolism, pyruvate metabolism, and glycolysis. Conclusions Eight prevalent species have significant SNP enrichments with the increasing number of SNP, among which only Eubacterium biforme, Eubacterium hallii and Ruminococcus obeum have relatively high species abundances. Many genes in the microbiomes also presented characteristic SNP distributions between the wet season and the dry season. This implies that the seasonal changes might indirectly impact the mutation patterns for specific species and functions for the gut microbiome of the population that lives in traditional lifestyles through changing the diet in wet and dry seasons, indicating the role of these variants in these species’ adaptation to the changing environment and diets.

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Seasonal Variation of Rainy and Dry Season Per Capita Water Consumption in Freetown City Sierra Leone

Water ◽

10.3390/w13040499 ◽

2021 ◽

Vol 13 (4) ◽

pp. 499

Author(s):

Salmatta Ibrahim A ◽

Fayyaz Ali Memon ◽

David Butler

Keyword(s):

Seasonal Variation ◽

Water Use ◽

Water Consumption ◽

Low Income ◽

Rainy Season ◽

Predictor Variable ◽

Dry Season ◽

Data Set ◽

Per Capita ◽

End Use

Ensuring a sustainable urban water supply for developing/low-income countries requires an understanding of the factors affecting water consumption and technical evidence of individual consumption which can be used to design an improved water demand projection. This paper compared dry and rainy season water sources available for consumption and the end-use volume by each person in the different income groups. The study used a questionnaire survey to gather household data for a total of 398 households, which was analysed to develop the relationship between per capita water consumption characteristics: Socio-economic status, demographics, water use behaviour around indoor and outdoor water use activities. In the per capita water consumption patterns of Freetown, a seasonal variation was found: In the rainy season, per capita water consumption was found to be about 7% higher than the consumption for the full sample, whilst in the dry season, per capita water consumption was almost 14% lower than the full survey. The statistical analysis of the data shows that the average per capita water consumption for both households increases with income for informal slum-, low-, middle- and high-income households without piped connection (73, 78, 94 and 112 L/capita/day) and with connection (91, 97, 113 and 133 L/capita/day), respectively. The collected data have been used to develop 20 statistical models using the multiple linear stepwise regression method for selecting the best predictor variable from the data set. It can be seen from the values that the strongest significant relationships of per capita consumption are with the number of occupants (R = −0.728) in the household and time spent to fetch water for use (R = −0.711). Furthermore, the results reveal that the highest fraction of end use is showering (18%), then bathing (16%), followed by toilet use (14%). This is not in agreement with many developing countries where toilet use represents the largest component of indoor end use.

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