The functional response of copepodid stages to adult ofParabroteas sarsi (copepoda, calanoida) (original) (raw)
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Life-stage differences in the diet of Parabroteas sarsi (Daday) (Copepoda, Calanoida): A field study
Limnologica - Ecology and Management of Inland Waters, 1999
The diet of P. sarsi in different life-stages from copepodid I to adult was investigated. Gut contents of copepodid I to II consisted mainly of algae such as diatoms and dinoflagellates. From copepodid III to adult stages the composition of the diet changed towards the inclusion of nauplii, cladocerans and copepods. The importance of the algae on the diet decreased with the inclusion of the prey items. Copepods were the most important components of the diet from C V to adult. Differences in the capture and ingestion of cladocerans and copepods were found. Diet of P. sarsi can be characterized as diverse consisting of diatoms, phagotrophic algae, protozoans, rotifers and nauplii from C I to C III and consisting mainly of carnivorous items from C IV to adult. The ability to eat a variety of food allows the copepods to modify their diet with varying conditions in the food environment. The effect of these diversity in the diet seems to be advantageous, specially in stressed environments imposed by episodes of drying.
Limnology and Oceanography, 2001
Predation is thought to be an important source of mortality in the early life stages of fish and copepods on Georges Bank. Omnivorous copepods may be predators on copepod eggs and nauplii, but data on feeding rates or selectivity are scarce. As part of the GLOBEC Georges Bank program, we generated functional response curves for the omnivorous copepods Metridia lucens, Centropages typicus, and Temora longicornis feeding on the eggs and nauplii of Calanus finmarchicus or Pseudocalanus spp. in shipboard predation trials. Neither C. typicus nor M. lucens reached saturation feeding on Calanus eggs until prey concentration was Ͼ400 L Ϫ1 . Individual M. lucens and C. typicus ingested up to 34 Ϯ 9 (mean Ϯ SD, n ϭ 3) and 24 Ϯ 14 eggs d Ϫ1 , respectively (6ЊC). T. longicornis was more abundant in late spring, when they ingested Calanus eggs at rates similar to those of C. typicus. At ambient prey concentrations, ingestion rates of Calanus nauplii were higher than rates of Calanus eggs for the predator M. lucens but were similar for C. typicus. Advanced naupliar stages were less susceptible to predation than young stages. Pseudocalanus nauplii moved faster and were ingested at lower rates than similarly sized Calanus nauplii. Predation rates increased with increasing temperature for the warm-water species C. typicus but decreased for the cold-water species M. lucens. These results may contribute to models predicting the development of copepod populations and their availability to larval fish.
Hydrobiologia, 2001
Growth, reproduction and biochemical composition were analyzed for the copepod Argyrodiaptomus furcatus fed on the alga Ankistrodesmus gracilis grown in different media. The ingestion of this copepod by larvae of two species of tropical fishes was also evaluated. The mean peak density of the copepod population was 1369 individuals l−1 for all four diets used, and the highest was 1387 individuals l−1 on diet ARV (algae + ration + vitamins). A small copepod, A. furcatus tends to have a short life span. The smallest females did not attain maturity in the shortest time on all diets used. Food quality may play a major role in the dynamics of the biochemical composition of this copepod. Argyrodiaptomus furcatus was a more important food item for larvae of tambaqui (Colossoma macropomum) than of pacu (Piaractus mesopotamicus). However, it made up a large part of the gut contents of larvae of both species.
Hydrobiologia, 2000
Parabroteas sarsi is a predaceous calanoid copepod that inhabits both shallow temporary fishless ponds and deep fish lakes of Patagonia and Antarctica. The aim of this study was to analyse the effect of P. sarsi on the plankton structure of a deep Andean lake (>100 m depth) and the zooplankton vertical distribution in order to asses a possible vertical refuge of the predatory copepod against visual fish predation. We tested the extent to which the trophic cascade effect of this predator propagates through the food web. We carried out a vertical sampling in Lake Rivadavia (Patagonia, Argentina) in order to assess zooplankton distribution. P. sarsi showed a vertical distribution towards deeper layers of the water column both at midday and at night, indicating that the copepod had an effective refuge against visual predation. Additionally, we carried out both field and laboratory experiments with the presence of P. sarsi. The predator was observed to affect significantly the survival of the copepod Boeckella michaelseni both in laboratory and field experiments. On the contrary, rotifers and adults of Daphnia cf. commutata were not substantially affected by the predator. B. michaelseni mouthparts revealed an omnivorous diet; therefore a broad phytoplanktonic size spectrum could be affected by this copepod. However, no cascade effect was observed due to the presence of P. sarsi despite the decrease of B. michaelseni abundance.
Helgoland Marine Research, 2002
This study focuses on selective feeding by developmental stages of two oceanic copepods, Calanus finmarchicus and Calanus helgolandicus from nauplii to adults. A mixture of four algal species of different biochemical composition, Prorocentrum nanum (dinoflagellate), Thalassiosira minima (diatom), Rhodomonas baltica (cryptophyte) and Dunaliella tertiolecta (chlorophyte), added in an equal biovolume, was used in three different experimental setups. In setup 1 the algal species were present as single cells of similar size (14 µm). In setup 2 the diatom T. minima was present in chains of two or three cells and was therefore larger than the other algae, while the biovolume of all species remained the same. In setup 3, the diatom T. minima was excluded from the mixture. Feeding selectivity of the copepods was assessed in relation to the quality of the algal species expressed in terms of carbon and nitrogen content, fatty acid composition, and chain length of the diatom. The results show that younger stages and adult females of C. finmarchicus and C. helgolandicus did not show a preference for an algal species when the algae were of similar size. In the feeding experiments where the diatoms were offered as chains, both copepod species showed a selective behaviour only on the basis of algal size. Individual ingestion rates increased from 0.4 to 0.7 µg C day-1 for nauplii of both species to 5 µg C day-1 for adult females of C. helgolandicus to 12 µg C day-1 for C. finmarchicus. Individual filtration rates ranged from 5 ml day-1 for C. finmarchicus nauplii to 70-98 ml day-1 for adult females, and from 3 ml day-1 for C. helgolandicus nauplii to 35-46 ml day-1 for adult females. Ingestion and filtration rates per unit body carbon decreased gradually in both copepod species with increasing body carbon. The daily ingested amount of food decreased for C. finmarchicus from 124-134% of the body carbon for nauplii to 19% of the body carbon for adult females, and for C. helgolandicus from 117-137% of the body carbon for nauplii to 13-26% of the body carbon of adult females.
Limnology and Oceanography, 1985
The size of copepod prey strongly influenced dietary selectivity by Euchaeta elongata. Adult females (4.2-mm prosome length) showed highest predation rates on adult copepod prey 650-1,000 pm long and on intermediate sized copepodid stages of Calanus pacz$cu+s. Selective feeding curves of copepodid stages IV and V of E. elongata showed a slight shift toward smaller prey. The prosome length of the primary prey was 70% the length of the second basipodal segment of the maxilliped for CIV, CV, and adult females of E. elongata. In both single and multispecies experiments at two concentrations, predation rates of adult female E. elongata seemed to be invariably focused on prey 650-1,000 pm long. Because E. elongata can consume adults of small copepod prey and the young copepodid stages of large copepod prey, it causes mortality of the entire copepod assemblage. Apparent recognition of a preferred prey, Pseudocalanus spp., and the nonpreferred cyclopoids seems to depend partly on their activity patterns. Thus, although size is an important determinant of dietary selectivity, species-specific behavioral differences can also influence feeding rates. Variations in predatory feeding activity on copepod prey were closely related to diel vertical migrations of E. elongata. The number of adult females with ingested prey began to increase soon after sunset, when the predatory copepod entered the surface layers containing prey of the preferred size, thus corroborating the selective feeding pattern observed in the laboratory. The timing of the migrations coincided well with sunset (ascent) and sunrise (descent) in winter, spring, and summer.
Journal of Plankton Research, 2013
Laboratory experiments were conducted to study the combined effect of temperature (8, 13, 19 and 248C), food type and food concentration on the grazing rates of the adult stages of the calanoid copepod Centropages chierchiae. As prey, the diatom Phaeodactylum tricornutum and the dinoflagellate Gymnodinium sp. (both ca. 15 mm cell diameter) were used at a range of carbon concentrations similar to the ones experienced in nature (6.4 to 393.8 mC L 21 ). Ingestion rates increased linearly with food concentration and did not differ between prey types. When comparing the effect of temperature, highest clearance and ingestion rates were obtained at 198C, whereas no difference was observed among the other temperatures. Daily rations varied between 1.2 and 183.5% body carbon day 21 . Additional experiments were conducted to study the selective feeding behaviour of C. chierchiae when offered a mixture of different prey types. Selective feeding was dependent on food concentration; at low food levels, large cells were selected (Ditylum brightwellii), whereas at medium and high food concentrations no clear selection patterns were observed. In contrast to other studies, no positive selection of dinoflagellates over other algal food was found.
Dietary Change during Development in the Freshwater Calanoid Copepod Epischura lacustris Forbes
Canadian Journal of Fisheries and Aquatic Sciences, 1986
ABSTRACT The diet of the freshwater calanoid copepod Epischura lacustris from C2 to adult stage was examined with predation experiments, grazing experiments, and stomach content analyses. There was a transition from an exclusively herbivorous diet in early copepodid stages to an omnivorous diet in adults. Laboratory predation experiments revealed that C2 and C3 were incapable of ingesting Bosmina (0.25–0.35 mm), but from C4 to C6, ingestion rate of Bosmina increased with developmental stage. The order or prey selection for adult Epischura was Bosmina over Diaptomus and Cyclops. Grazing rate on small algae (<10 μm) increased with developmental stage. Zooplankton remains were only found in the guts of stages older than C2; cladocerans and crustacean eggs were the most common zooplankton food. Algae with longest linear dimensions greater than 10 μm (e.g. Sphaerocystis, Dinobryon, and diatoms) were common in the guts of all developmental stages of Epischura. The occurrence of small unicells (<10 μm) in the guts decreased with developmental stage.
Sources of variability in attack rates of Euchaeta elongata Esterly, a carnivorous marine copepod
Journal of Experimental Marine Biology and Ecology, 1982
An accurate and precise measure of ingestion is important for understanding trophic interactions in the plankton. This paper describes effects on the ingestion rate of the carnivorous marine copepod Euchaeta elongata Esterly of several biotic and abiotic factors operating in the pelagic environment. Sources of variability in the attack rate included, in order of decreasing influence: (1) light, (2) prey activity (live vs. heat killed), (3) predator condition (with and without antennae), (4) prey type, (5) time of day, (6) prey density, and mixing regime. While these responses were observed in the laboratory, they are consistent with E. elongata's behavior in the field. No significant changes were noted in the attack rate in response to the presence of prey exudate, number of predators per experiment duration, container size, reproductive state of predator, or temperature. The adult female copepods were exclusively carnivorous. An experimental method based on these results is described for use in further investigations on the predatory feeding ecology of E. elongata. ' Contribution No. 1262 from the School of Oceanography, University of Washington, Seattle, WA 98195. U.S.A. 0022-098 l/82/0000-0000/$02.75 0