Seasonal Feeding Patterns Research Articles

Seasonal Feeding Activity and Ontogenetic Dietary Shifts of the Common Carp (Cyprinus carpio) in Lake Arekit, a Small, Eutrophic Lake in Ethiopia

ABSTRACTSeasonal feeding activity and ontogenetic dietary shifts of Cyprinus carpio (Linnaeus, 1758) were examined using 209 fish samples from Lake Arekit, Ethiopia. Among the 209 specimens, 174 (83.3%) displayed a range of dietary items in their stomachs. The species’ feeding patterns were determined through numerical indexes (frequency of occurrence and volumetric contribution) and composite indexes (index of preponderance [IOP] and Geometric Index of Importance [GIIi]). Detritus emerged as the primary food source for C. carpio, followed by macrophytes, insects and zooplankton. A lesser amount of phytoplankton, nematodes and ostracods were also consumed. On the basis of the findings, C. carpio can be classified as a detri‐omnivore, as it consumes benthic species like nematodes, ostracods and insect larvae. Seasonal fluctuations in food item consumption were noted (p < 0.05), with higher intake during the rainy season and reduced consumption in the dry season. There was a distinct ontogenetic shift in the relative importance of food items and showed significant variations in food preferences among size groups (p < 0.05). The contributions of animal‐origin food categories (ostracods, zooplankton and insects) were important in the diet of the smaller size class, whereas food of plant origin (macrophytes) and detritus were more important in the diet of adults. Understanding the seasonal feeding patterns and ontogenetic dietary shifts of C. carpio in Lake Arekit provides crucial insights into their ecological role within the lake's ecosystem and highlights their adaptability to eutrophic conditions.

Токсичные и биогенные элементы в органах и тканях белой куропатки (Lagopus lagopus L., 1758) на севере Красноярского края (обзор)

Studying the concentration of biogenic and toxic microelements in the body tissues of wild animals is relevant for organizing regional environmental monitoring, assessing the state of populations and ensuring the safety of meat and wild products. The studies were carried out to determine the content of biogenic and toxic elements in the organs and tissues of the willow ptarmigan in the north of the Krasnoyarsk Region, Russia, where different levels of technogenic pollution are expected. The iron, copper, nickel, lead, and cadmium content in the pectoral muscles and liver of willow ptarmigan (Lagopus lagopus L.) (n=162), bagged during five hunting seasons in 2005–2019, were determined using atomic absorption spectrometry. The levels of lead, cadmium and iron in the tissues were significantly higher in contaminated areas, while the copper levels did not differ. Element concentrations in liver and skeletal muscle in impact areas were highly correlated with each other. This may be related to common sources of pollutant emissions. Sex differences in micronutrient content can be determined by spatial differentiation of the sexes during migration, seasonal feeding patterns, and the specific birds’ metabolism in reproductive period. Cadmium and lead content in liver and muscle tissue samples from impact areas exceeded current food hygiene standards, which may pose a threat to consumers. Probably, high levels of lead and cadmium reflect the increased content of metals in food items primarily willow sprouts and buds, which are the most important winter food for ptarmigan.

Seasonal Diet Changes and Trophic Links of Cold-Water Fish (Coregonus albula) within a Northern Lake Ecosystem

The seasonal feeding patterns of the cold-adapted fish, Coregonus albula, are poorly studied in high-latitude lakes but could provide insight for predicting the effects of global warming. We examined vendace’s diet composition, traced the carbon and nitrogen isotope ratios from producers to consumers in the food web, and estimated vendace’s trophic position in a subarctic lake (the White Sea basin). Results showed the vendace to be a typical euryphagous fish, but clear seasonal differences were found in the relative importance of plankton and benthos in the diet. The vendace consumed primarily benthic amphipods in the summer, planktonic cladocerans in the autumn, and copepods in the winter–spring (under ice); larvae of aquatic insects were the second-most important food items throughout the year. Because of the substantial proportion of fish embryos in its diet, the vendace had a trophic position similar to that of a predatory fish (perch). The Bayesian food source-mixing model revealed that the majority of vendace energy derives from planktonic copepods. The dominant Cyclops had the lowest carbon isotope values, suggesting a carbon-depleted diet typical for methanotrophic bacteria, as its probable food source was in a lake under ice. Understanding the feeding patterns of vendace provides information to better predict the potential biotic effects of environmental change on lake ecosystems.

Ticks (Acari: Ixodida) on synanthropic small and medium-sized mammals in areas of the northeastern United States infested with the Asian longhorned tick, Haemaphysalis longicornis

The northeastern United States (US) is a hotspot for tick-borne diseases. Adding to an already complex vector landscape, in 2017 large populations of the invasive Haemaphysalis longicornis, the Asian longhorned tick, were detected in New Jersey (NJ) and later found to be widespread from Connecticut to Georgia. In its native range in northeastern Asia, H. longicornis is considered an important vector of deadly pathogens to humans, companion animals, and livestock. To identify the primary hosts of H. longicornis, we surveyed synanthropic small and medium-sized mammals in three different sites in suburban New Brunswick, NJ. Specifically, we collected approximately 9,000 tick specimens belonging to nine species from 11 different species of mammals sampled between May and September 2021. We found that H. longicornis feeds more frequently on rodents than previously thought, and that this invasive tick is likely exposed to important enzootic and zoonotic pathogens. Overall, we obtained detailed information about the seasonal dynamics and feeding patterns of six tick species common in the northeastern US, Haemaphysalis longicornis, Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis, Ixodes texanus and Ixodes cookei. We found that unlike I. scapularis that feeds on mammals of all sizes, H. longicornis feeds on hosts following the general pattern of A. americanum, favoring larger species such as skunks, groundhogs, and raccoons. However, our survey revealed that unlike A. americanum, H. longicornis reaches high densities on Virginia opossum. Overall, the newly invasive H. longicornis was the most numerous tick species, both on multiple host species and in the environment, raising significant questions regarding its role in the epidemiology of tick-borne pathogens, especially those affecting livestock, companion animals and wildlife. In conclusion, our findings provide valuable insights into the tick species composition on mammalian hosts in NJ and the ongoing national expansion of H. longicornis.

A systematic review on the feeding ecology of Sloth Bear Melursus ursinus Shaw, 1791 in its distribution range in the Indian subcontinent

The Sloth Bear being myrmecophagous is specialized to feed on ants, termites, and fleshy food; however, no discernible comparison exists on a diet, seasonal feeding pattern, and factor influence in a different habitat of an Indian sub-continent. A review of available literature suggested the dominance of plant matter in the Sloth Bear diet during the summer season, while an equal quantum of plant & animal matter was recorded in the monsoon & winter seasons. Fleshy fruits, flowers, flower buds, delicate leaves, and sometimes roots are considered plant food items in different studies, while ants, termites, honey, honey wax, and carrion feed are recorded as animal food items. Availability and accessibility of food materials in the different seasons, energy requirements, geographical variations, and human interference are notable factors influencing the feeding strategy of Sloth Bears. Cumulative data on food & feeding behavior of Sloth Bears helps to understand the pivotal role of species across various habitats. A systematic review of all the available studies to understand the diet of Sloth Bears in different seasons across its distribution range is presented in this paper, which can be a holistic approach to know the habitat selection with reference to the availability of food. A better understanding of such behavior also provides a key strategy for the management of large mammals in different geographical areas.

Contribution of the Baikal Amphipod to the Feeding Pattern of Perch in the Littoral Zone of Lake Onega

Abstract. The seasonal feeding pattern of juvenile perch in Petrozavodsk Bay of Lake Onega was studied. It was shown that in the fourth to sixth years of their life, a benthic type of feeding predominates. The fish that inhabit the littoral zone feed actively on the Baikal amphipod, a new food item. During the summer-autumn season, the colonizer accounts for over 50% of the biomass in the stomach of juvenile perch. The invasion of Lake Onega by the Baikal amphipod has thus led to changes in the structure of littoral communities and the availability of a new food item for the fish. Considering the resistance of the Baikal amphipod to unfavorable environmental factors, it is important to study its spatial expansion and the possible penetration of this amphipod via tributaries to other water bodies in the Lake Onega Lake catchment area.
 Keywords: freshwater ecosystem, perch, trophic interactions, Baikal amphipod

Seasonal hydromedusan feeding patterns in an Eastern Boundary Current show consistent predation on primary consumers

Abstract Cnidarian jellyfish can be dominant players in the food webs of highly productive Eastern Boundary Currents (EBC). However, the trophic role of inconspicuous hydromedusae in EBCs has traditionally been overlooked. We collected mesozooplankton from five stations along two cross-shelf transects in the Northern California Current (NCC) during winter and summer of 2018–2019. We analyzed gut contents of 11 hydromedusan species and the prey community to (i) determine prey resource use by hydromedusae and (ii) determine temporal shifts in the trophic niche of hydromedusae, focusing on the two most collected species (Clytia gregaria and Eutonina indicans). Hydromedusae in the NCC fed mostly on copepods, appendicularians and invertebrate larvae. Nonmetric multidimensional scaling of hydromedusan diets showed seasonal shifts in prey resource driven by the abundant C. gregaria, which fed mostly on copepod eggs during winter and fed mostly on appendicularians and copepods during summer. Prey selectivity for copepod eggs increased during winter for C. gregaria and E. indicans. Intriguingly, theoretical ingestion rates show that both species acquire similar amounts of carbon during upwelling and nonupwelling conditions. Hydromedusae’s consistent presence and predation impact across seasons may lead to significant effects in carbon and energy transfer through the NCC food web.

Seasonal abundance and feeding patterns of the invasive racer goby (Babka gymnotrachelus) in the littoral zone of a lowland European river

Seasonal abundance and feeding patterns of the invasive racer goby (Babka gymnotrachelus) in the littoral zone of a lowland European river

Energetics as common currency for integrating high resolution activity patterns into dynamic energy budget-individual based models

Dynamic energy budget individual-based models (DEB-IBMs) provide a well-tested framework for modelling the acquisition and use of energy throughout the life cycle of organisms. These models are often developed using species-specific data to link behaviour and physiology and predict how individuals and populations perform in changing environments. Novel bio-logging technology, applied to free-ranging animals, provide detailed information about individual behavioural variations and responses to the environment. However, so far, no DEB-IBM has attempted to link and parameterise energy dynamics with the fine-scale activity data obtained by bio-logging to answer questions related to life history events in wild populations. The aim of this study is, therefore, to develop and test a DEB-IBM framework which integrates individuals behaviour obtained from high-resolution activity data. Our approach uses data collected with GPS and accelerometer tags attached to two muskox (Ovibos moschatus). The individuals had different fates: one survived the Arctic winter, while the other died. Applying hidden Markov models to accelerometer data, we quantified the variation in behavioural activity budgets (in stationary, feeding and transit) in relation to environmental conditions. We subsequently test how differences in time allocation affect fitness outcomes such as body mass, energy reserves and survival. The proportion of time spent feeding by each animal is used within the DEB-IBM framework to scale the functional response for food acquisition. Simulations using the seasonal feeding budget of the deceased individual lead to drastically reduced energy reserves and body weight during the Arctic winter, and to elevated probabilities of mortality by the end of winter. In contrast, simulations using the seasonal feeding pattern of the surviving muskox, result in much less pronounced losses in reserves and body weight, leading to negligible over-winter mortality. The framework we present here uses standardized modelling techniques, is applicable across species and can easily be extended to include other fitness measures or environmental stressors. Moreover, our framework provides the foundation needed for future studies to link individual movements, energetic processes, life history events and population dynamics in wildlife, which would open up possibilities to test how changing (future) environmental conditions influence animal decision-making and ultimately population level consequences.

Seasonal feeding patterns of Atlantic bluefin tuna (Thunnus thynnus) in the Strait of Gibraltar

The Strait of Gibraltar (SoG) houses a large diversity of marine species including large pelagic animals that use this area as permanent or temporary habitat. In particular, the SoG is home to a population of adult and sub-adult Atlantic bluefin tuna (Thunnus thynnus) that occurs there for most of the year. To gain further insight into the life history of this ABFT population, seasonal feeding patterns were investigated combining stomach content analysis (SCA) and stable isotopes analysis (SIA) of muscle and liver tissues. Our results reveal seasonal variations in feeding patterns, which are evidenced by a significant shift in the diet composition and the highest food consumption rates that take place in spring, prior to the spawning season. These changes in feeding habits are consistent with the varying energetic needs along the species’ annual biological cycle. The present observations confirm the SoG as an important foraging ground for ABFT resident populations and may have further implications for the management of the resource.

Seasonal dynamics of zooplankton resource use revealed by carbon amino acid stable isotope values

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 531:143-154 (2015) - DOI: https://doi.org/10.3354/meps11319 Seasonal dynamics of zooplankton resource use revealed by carbon amino acid stable isotope values Jens M. Nielsen*, Monika Winder Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden *Corresponding author: jens.nielsen@su.se ABSTRACT: Reliable tracer techniques are fundamental to retrieving accurate information on consumer dietary resource use in dynamic ecosystems. Analysis of δ13C values in essential amino acids has shown great promise in effectively capturing consumer food sources, since essential amino acids are not synthesized by heterotrophic organisms but instead routed directly from dietary sources to consumers, resulting in negligible 13C trophic discrimination. We assessed seasonal feeding patterns of a widespread key copepod species (Acartia spp.) in the northern Baltic proper using complementary approaches: bulk δ13C and δ15N values, δ13C values of essential amino acids, and quantitative phytoplankton taxonomic data. Our results showed distinct differences between Acartia and seston δ13C essential amino acid values measured at weekly to monthly sampling intervals, which indicated that Acartia preferentially utilized specific dietary resources that comprised only parts of the total phytoplankton composition (varying from 19.7% to 81.4% during the season). Results also indicated that care should be taken when inferring trophic position from bulk stable isotopes when consumers are highly selective, since isotope values of seston may not accurately reflect consumer specific diet resource uptake. Analysis of δ13C values in essential amino acids was shown to be a promising tool to accurately trace consumer resource use in complex natural systems. KEY WORDS: Stable isotopes · Amino acids · Acartia · Zooplankton · Phytoplankton · Food webs Full text in pdf format PreviousNextCite this article as: Nielsen JM, Winder M (2015) Seasonal dynamics of zooplankton resource use revealed by carbon amino acid stable isotope values. Mar Ecol Prog Ser 531:143-154. https://doi.org/10.3354/meps11319 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 531. Online publication date: July 02, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

To fast or feed: an alternative life history for anadromous brook trout Salvelinus fontinalis overwintering within a harbour.

The seasonal feeding pattern of sea-run brook trout Salvelinus fontinalis was studied from November to May 2010-2012 in Antigonish Harbour, Nova Scotia, Canada (45° 38' N; 61° 55' W). Sixty-three S. fontinalis (mean ± s.d. fork length = 330 ± 70 mm and mass = 536 ± 351 g) captured had fed predominantly on fishes (Fundulidae and Gasterosteidae). Percentage of empty stomachs was highest during autumn (18%) and winter (22%) and lowest in spring (7%). Stomach fullness increased from autumn to a maximum during winter, relating to near-zero body temperatures which may have effectively stopped gastric evacuation. Although feeding occurred during winter (December to March), consumption rates were calculated as negative values, and subsequently returned to positive values in spring (April to May). The over-winter life-history strategy of this sea-run S. fontinalis population appears to be a feeding marine migration in which fish continually increase body condition, representing an alternative to the more common overwintering strategy of starvation in fresh water until spring.

A model to resolve organochlorine pharmacokinetics in migrating humpback whales.

Humpback whales are iconic mammals at the top of the Antarctic food chain. Their large reserves of lipid-rich tissues such as blubber predispose them to accumulation of lipophilic contaminants throughout their lifetime. Changes in the volume and distribution of lipids in humpback whales, particularly during migration, could play an important role in the pharmacokinetics of lipophilic contaminants such as the organochlorine pesticide hexachlorobenzene (HCB). Previous models have examined constant feeding and nonmigratory scenarios. In the present study, the authors develop a novel heuristic model to investigate HCB dynamics in a humpback whale and its environment by coupling an ecosystem nutrient-phytoplankton-zooplankton-detritus (NPZD) model, a dynamic energy budget (DEB) model, and a physiologically based pharmacokinetic (PBPK) model. The model takes into account the seasonal feeding pattern of whales, their energy requirements, and fluctuating contaminant burdens in the supporting plankton food chain. It is applied to a male whale from weaning to maturity, spanning 20 migration and feeding cycles. The model is initialized with environmental HCB burdens similar to those measured in the Southern Ocean and predicts blubber HCB concentrations consistent with empirical concentrations observed in a southern hemisphere population of male, migrating humpback whales. Results show for the first time some important details of the relationship between energy budgets and organochlorine pharmacokinetics.

Diet composition and seasonal feeding patterns of a freshwater ringed seal (Pusa hispida saimensis)

AbstractThe Saimaa ringed seal (Pusa hispida saimensis) is one of the few freshwater seal populations worldwide. The major conservation issue of this critically endangered population is bycatch mortality. We used digestive tract content and stable isotopes (δ13C andδ15N) to estimate the diet and seasonal feeding patterns for gaining better understanding of the seals feeding habits and potential conservation implications. The diet was similar across age groups. Altogether 15 fish species were identified and the most important were smelt (Osmerus eperlanus), ruff (Gymnocephalus cernuus), perch (Perca fluviatilis), vendace (Coregonus albula) and cyprinids. The highδ15N values suggested that the seals lose weight during winter and spring. Additionally the drop inδ15N values indicated that pups start to recover from postweaning stress and gain weight around the age of 6 mo. The isotope values differed regionally, which emphasizes that samples from consumers and prey should be collected from the same regions to improve interpretation of the stable isotopic results. Overall, diet composition suggests minimal to nonexistent competition with commercial or recreational fishing. However, observed weight loss of pups during summer may be related to higher risk of bycatch and this should be taken into account when planning temporal fishing closures.

Evaluation of Seasonal Feeding Patterns of West Nile Virus Vectors in Bernalillo County, New Mexico, United States: Implications for Disease Transmission

Many mosquito species take bloodmeals predominantly from either birds or mammals. Other mosquito species are less host-specific and feed readily on both. Furthermore, some species tend to alter their feeding patterns over the course of the year; early in the mosquito season such species may feed primarily on a particular host type, and subsequently take an increasingly larger proportion of their bloodmeals from an alternative host type as the season progresses. We have examined the feeding patterns of the three mosquito species found in Bernalillo County, NM: Culex quinquefasciatus (Say), Culex tarsalis (Coquillett), and Aedes vexans (Meigen). Specifically, we seek to determine if any of these species displays a seasonal shift in terms of its host utilization pattern. Our analysis focuses on these three species because they are all considered to be competent vectors for the West Nile virus (WNV). Our current data for Cx. quinquefasciatus suggest that unlike elsewhere in its range, this species increases its proportion of avian bloodmeals as the season progresses. Alternatively, Ae. vexans feeds primarily on mammals, whereas Cx. tarsalis appears to feed on both mammals and birds throughout the mosquito season. A more complete understanding of the feeding habits of these three mosquito species may help to clarify the transmission dynamics of WNV in Bernalillo County.

Impact of temperature and prey shell thickness on feeding of the oyster drill Urosalpinx cinerea Say

Feeding rates and selection of the oyster drill Urosalpinx cinerea were investigated with several long term temperature alteration experiments. Oyster drill prey selection was assessed in terms of prey (oyster) size and shell thickness. Drills fed on oysters with thinner shells 86% of the time and selectively preyed on smaller (1g wet weight) oysters during colder months and larger (10g wet weight) oysters during warmer months. Analysis of U. cinerea seasonal feeding patterns showed virtually no feeding during winter months (January to March) and a significant increase to over 1 gram of prey tissue per week during summer (July to September). A nine month experiment compared feeding rates of U. cinerea at two different temperature levels: ambient seawater (control) and temperatures elevated 4°C above ambient. Oyster drills showed a 60% increase in feeding rate in the warmer treatment, especially during late summer, fall and early winter. Both temperature manipulation and annual feeding experiments revealed a significant temperature dependence of U. cinerea feeding rates. Seasonal or long-term seawater temperature changes related to climate change could strongly affect the predator–prey relationship between U. cinerea and its prey.

Canis latrans(Coyote) Habitat Use and Feeding Habits in Central West Virginia

Canis latrans (Coyote) populations are expanding throughout the eastern United States, making them the apex predator in many systems. Despite abundant research in the western United States, relatively little information exists on the space use or feeding patterns of Coyotes in the forested landscapes of the Appalachians. We used radio-telemetry and scat analysis to describe seasonal habitat use and feeding patterns of Coyotes in central West Virginia during 2006–2008. Odocoileus virginianus (White-tailed Deer) was the most common prey, occurring in 76% of scats collected in winter and 45% of scats collected in summer. Rodents were the most common prey item in summer, occurring in 48% of scats; other prey items occurred in <20% of scats. Coyotes selected for recently harvested forest stands while avoiding intact stands in both summer and winter. Despite exhibiting seasonal prey-switching behavior, Coyotes in this region do not alter habitat-use patterns with respect to season. Coyotes in our study seem to be opportunistic feeders that prefer areas with abundant cover. Their opportunistic feeding patterns may contribute to their rapid population expansion in this region.

Seasonal abundance and feeding patterns of copepods Temora longicornis, Centropages hamatus and Acartia spp. in the White Sea (66°N)

We have studied the seasonal dynamics of abundance and feeding characteristics of three species of calanoid copepods (Acartia spp., Centropages hamatus and Temora longicornis) in the White Sea from the surface water layer (0–10 m), in order to assess their role in the pelagic food web and to determine the major factors governing their population dynamics during the productive season. These species dominated in the upper water layer (0–10 m) from June through September, producing up to 3 generations per year. Data on the food spectra revealed all species to be omnivorous; but some inter- and intraspecific differences were observed. Generally, copepods consumed diatoms, dinoflagellates and microzooplankton. The omnivory index ‘UC’ (i.e., fatty acid unsaturation coefficient) varied from 0.2 to 0.6, which implied ingestion of phytoplankton. The different degree of selectivity on the same food items by the studied species was observed, and therefore, successful surviving strategy with minimal overlapping could be assumed. In total, the populations of the three studied copepod species grazed up to 2.15 g C m−2 day−1 and released up to 0.68 g C m−2 day−1 in faecal pellets. They consumed up to 50% of particulate organic carbon, or up to 85% of phytoplankton standing stock (in terms of Chl. a), and thus played a significant role in the transformation of particulate organic matter. Seasonal changes in abundance of the studied species depended mostly on water temperature in the early summer, but were also affected by food availability (Chl. a concentration) during the productive season.

Insights into the spatiotemporal component of feeding ecology: an isotopic approach for conservation management sciences

AbstractAim Bringing new approaches to trace spatiotemporal variations in animals’ feeding ecology, which is fundamental for wildlife management and conservation since the accessibility of animals to trophic resources plays a key role in the dynamics of populations and metapopulations.Location Western Mediterranean coast.Methods The analysis of naturally occurring stable isotopes constitutes an exceptional approach to assess variations in the trophic ecology of species within the spatiotemporal dimensions. Here, we examined the spatiotemporal heterogeneity in resource exploitation of a nuisance and overpopulated gull species with a great feeding plasticity, the Yellow‐legged gull Larus michahellis, by measuring the stable isotope ratios of carbon (13C/12C, δ13C), nitrogen (15N/14N, δ15N) and sulphur (34S/33S, δ34S) in different wing feathers.Results Tracing isotopic changes among feathers in relation to moulting sequence, we showed that isotopic analyses on first primary feathers were good indicators of breeding trophic ecology, while others, such as eighth secondary feathers, reflected the feeding behaviour during the non‐breeding period. This knowledge was then used to report on estimations of seasonal feeding patterns throughout the year for seven gull populations along the Western Mediterranean coast.Main conclusions The high diversity in the exploitation patterns of the foraging habitats found in the study area both at spatial and at temporal scale indicated the opportunistic feeding behaviour of Yellow‐legged gulls. Proposed isotopic approach has revealed as a useful tool to evaluate spatiotemporal variations in the feeding ecology of populations which may become clue for dealing with the management of wild species, not only nuisance populations but also endangered species. We finally pointed out the relevance of the isotopic variability among individuals to infer diet diversity and food availability of a given population, thereby allowing demographic forecasts when trophic resources vary in abundance.

Seasonal and diel abundance and feeding patterns of Chaoborus flavicans in Sang-Chun reservoir

To document the basic ecological aspects of Chaoborus species, which has never been reported in Korea, we attempted to identify the species, to monitor seasonal and vertical dynamics, and to elucidate trophic relations of the species in Sang-Chun reservoir. Using morphological characteristics, we identified the collected samples as C. flavicans. Also, we compared the distribution of C. flavicans, Daphnia rosea and chlorophyll a to observed seasonal dynamics. The increase of C. flavicans was observed 1–2 weeks after the increase of D. rosea. Survey of diel vertical migration patterns in the summer season showed that C. flavicans were in hypolimnion at daytime, but moved to the epilimnion at night. Finally, to determine trophic relationships in Sang-Chun reservoir, additional studies on the food web were undertaken by stable isotope analysis. Chaoborus flavicans I–II instars appear to be filter feeders based on carbon isotope values. Trophic levels of C. flavicans III–IV instars were shown to be higher than other zooplankton based on nitrogen isotope values.