scholarly journals Functional feeding response of Nordic and Arctic krill on natural phytoplankton and zooplankton

2020 ◽  
Vol 42 (2) ◽  
pp. 239-252
Author(s):  
Jory Cabrol ◽  
Anaïs Fabre ◽  
Christian Nozais ◽  
Réjean Tremblay ◽  
Michel Starr ◽  
...  
Keyword(s):  
Ingestion Rate ◽  
Trophic Levels ◽  
Feeding Response ◽  
Feeding Selectivity ◽  
Feeding Experiments ◽  
Energy Needs ◽  
Metabolic Costs ◽  
Coexisting Species ◽  
Natural Phytoplankton ◽  
Natural Communities

Abstract Krill species play a pivotal role in energetic transfer from lower to upper trophic levels. However, functional feeding responses, which determine how food availability influences ingestion rates, are still not well defined for northern krill species. Here, we estimated and compared the functional feeding responses on natural communities of phytoplankton and mesozooplankton of two coexisting species, Meganyctiphanes norvegica and Thysanoessa raschii. We tested the influence of the presence of phytoplankton on the ingestion rate and the selectivity of both krill species when feeding on zooplankton prey. We performed a series of feeding experiments using increasing concentrations of natural phytoplankton (64 taxa; 2 to >50 μm) and mesozooplankton (28 taxa; ~100–2000 μm) assemblages and the latter in presence and absence of phytoplankton. Results revealed that both krill species exhibited a Holling type III feeding response on phytoplankton. However, T. raschii was able to exploit efficiently the highest phytoplankton concentrations. Our experiments highlighted that the presence of phytoplankton modified the functional feeding response on mesozooplankton preys of M. norvegica, but not that of T. raschii. Similarly, the presence of phytoplankton influenced the feeding selectivity on mesozooplankton preys, although both species showed contrasting selectivity patterns. In addition, we estimated the energy needs in relation to the daily rations. T. raschii satisfied its energy needs by feeding either on high phytoplankton concentrations or on low mesozooplankton densities, whereas M. norvegica did not cover its metabolic costs efficiently by feeding on phytoplankton only, even at high phytoplankton concentrations.

Feeding By Oyster Larvae: The Functional Response, Energy Budget and A Comparison With Mussel Larvae

1985 ◽  
Vol 65 (3) ◽  
pp. 759-783 ◽  
Author(s):  
D. J. Crisp ◽  
A. B. Yule ◽  
K. N. White
Keyword(s):  
Ingestion Rate ◽  
Algal Species ◽  
Feeding Response ◽  
Ostrea Edulis ◽  
Influence Of Temperature ◽  
Energy Needs ◽  
Influence Of Temperature On ◽  
Veliger Larvae ◽  
Micro Organisms ◽  
Benthic Animals

Whereas there is a wealth of literature on the feeding of herbivorous holo-plankton, notably copepods, feeding by herbivorous larvae of benthic animals has been somewhat neglected. This paper considers the functional feeding response of veliger larvae of Ostrea edulis L., Crassostrea gigas (Thunberg) and Mytilus edulis L. fed on several micro-algal species. It also provides some data on the influence of temperature on feeding, and assesses the energy needs of the larvae in relation to their potential ingestion rate and to the availability in the sea of micro-organisms on which they feed.

scholarly journals Diets and Seasonal Ingestion Rates of Aurelia coerulea (Cnidaria: Scyphozoa) Polyps by in situ Feeding Experiments in Jiaozhou Bay, China

2021 ◽  
Vol 8 ◽  
Author(s):  
Wang Pengpeng ◽  
Zhang Fang ◽  
Guo Dongjie ◽  
Sun Song
Keyword(s):  
Prey Capture ◽  
Prey Availability ◽  
Ingestion Rate ◽  
Jiaozhou Bay ◽  
Gut Contents ◽  
Natural Diet ◽  
Ingestion Rates ◽  
Aurelia Coerulea ◽  
Feeding Experiments

The benthic scyphopolyp population is an important stage in the scyphozoan lifecycle. Nevertheless, few studies have detailed the natural feeding and quantified the energy flux of polyps based on field research. To better understand the scyphopolyp natural diet and seasonal variation patterns in the ingestion rate, in situ feeding experiments were conducted on Aurelia coerulea polyps in Jiaozhou Bay, China from August 2018 to April 2019. The diet of A. coerulea polyps was determined by gut content analysis. Digestion rates were also measured. Ingestion rates, based on the gut contents and digestion rates, were assessed monthly. Copepods, copepod nauplii, and ciliates were identified in the guts of A. coerulea polyps. Copepods with the bulk of total prey intake in number are an important source of nutrition for A. coerulea polyps in Jiaozhou Bay. Prey capture of A. coerulea polyps (prey polyp–1) varied among months, and was highly dependent upon the abundance of planktonic prey in the habitat. Copepods and copepod nauplii were digested more rapidly as temperature increased. Carbon weight-specific ingestion rate exhibited an obvious seasonal change, with the mean value of 0.13 ± 0.12 μg C μg C–1 d–1. More rapid digestion of prey at higher temperatures and larger prey availability would cause a higher ingestion rate in polyps. Scyphopolyps are widely distributed predators in littoral ecosystems and they may play an important role in plankton–benthos coupling by transferring energy from the water column to the benthos. Massive scyphopolyps blooms may influence pelagic ecosystems.

scholarly journals Species-specific content of thiamin (vitamin B1) in phytoplankton and the transfer to copepods

2020 ◽  
Vol 42 (3) ◽  
pp. 274-285
Author(s):  
Emil Fridolfsson ◽  
Elin Lindehoff ◽  
Catherine Legrand ◽  
Samuel Hylander
Keyword(s):  
Vitamin B1 ◽  
Prey Type ◽  
Water Soluble ◽  
Trophic Levels ◽  
Specific Content ◽  
Feeding Experiments ◽  
Per Se ◽  
Aquatic Food ◽  
Species Specific ◽  
Important Building Block

Abstract Thiamin (vitamin B1) is primarily produced by bacteria and phytoplankton in aquatic food webs and transferred by ingestion to higher trophic levels. However, much remains unknown regarding production, content and transfer of this water-soluble, essential micronutrient. Hence, the thiamin content of six phytoplankton species from different taxa was investigated, along with the effect of thiamin amendment on thiamin content. Furthermore, thiamin transfer to copepods was estimated in feeding experiments. Prey type, not phytoplankton thiamin content per se, was the most important factor for the transfer of thiamin, as it was lowest from filamentous Cyanophyceae and highest from more easily ingested prey like Dunaliella tertiolecta and Rhodomonas salina. Cyanophyceae had the highest thiamin content of the investigated species, eightfold higher than the lowest. Phytoplankton varied in thiamin content related to the supply of thiamin, where thiamin addition enabled higher thiamin content in some species, while copepod thiamin content was less variable. In all, thiamin transfer is not only dependent on the prey thiamin content, but also the edibility and/or digestibility is of importance. Thiamin is essential for all organisms, and this study constitutes an important building block to understanding the dynamics and transfer of thiamin in the aquatic food web.

Feeding selectivity of Corbicula fluminea (Bivalvia) on natural phytoplankton

Hydrobiologia ◽  
1995 ◽  
Vol 312 (3) ◽  
pp. 171-182 ◽  
Author(s):  
Demetrio Boltovskoy ◽  
Irina Izaguirre ◽  
Nancy Correa
Keyword(s):  
Corbicula Fluminea ◽  
Feeding Selectivity ◽  
Natural Phytoplankton

Predation on Larval Fish by Atlantic Mackerel Scomber scombrus, with a Comparison of Predation by Zooplankton

1987 ◽  
Vol 44 (11) ◽  
pp. 2012-2018 ◽  
Author(s):  
P. Pepin ◽  
S. Pearre jr. ◽  
J. A. Koslow
Keyword(s):  
Larval Fish ◽  
Prey Preference ◽  
Alternative Prey ◽  
Feeding Response ◽  
Feeding Selectivity ◽  
Atlantic Mackerel ◽  
Scomber Scombrus ◽  
Capture Success ◽  
Invertebrate Predators ◽  
Predation Rates

This study reports on the feeding selectivity of Atlantic mackerel, Scomber scombrus, on larval fish (3-10 mm in length) presented as part of natural zooplankton assemblages. As with other vertebrate planktivores, prey preference was positively size selective, contrary to the pattern observed for several invertebrate carnivores. Larval fish density did not significantly influence predation rates. Furthermore, there was no evidence of either switching or saturation of the predator's functional feeding response with changes in alternative prey abundance, again unlike invertebrate predators. A review of previous experiments revealed that capture success of larval fish by predators is a function of the size of larval fish relative to the size of the predator, independent of predator taxa (i.e. vertebrate versus invertebrate).

scholarly journals Uptake of plastic microbeads by ciliate Paramecium aurelia

2020 ◽  
Vol 9 (2) ◽  
pp. 1-9
Author(s):  
Failasuf Aulia Nugroho ◽  
Janusz Fyda
Keyword(s):  
Food Web ◽  
Clearance Rate ◽  
Aquatic Environment ◽  
Ingestion Rate ◽  
Trophic Levels ◽  
Ciliated Protozoa ◽  
Maximum Capacity ◽  
Low Concentration ◽  
Wide Range ◽  
Food Vacuoles

Microplastics (MPs) are small fraction of plastics that are less than 5 mm in length. They are bountiful and widespread pollutants in the aquatic environment. A wide range of organisms which play an important role in the food web, ingest microplastic particles and transfer them to the higher trophic levels. In this work, ingestion of fluorescent polystyrene beads 2 µm of diameter by ciliated protozoa Paramecium aurelia in different concentrations and times of exposure was studied. We studied also the ingestion and clearance rate as well as formation of food vacuoles. The highest uptake of beads by ciliates reached 1047.2 ± 414.46 particles after 10 min of incubation. Food vacuoles formation reflected the ingestion rate of P. aurelia, which increased at higher beads concentration up to the10th minute of incubation and decreased afterwards. On the contrary, the clearance rate persisted to be higher at low concentration. These findings showed that maximum capacity of microplastics ingestion by paramecia depended on beads concentration and on time of exposure.

scholarly journals Salinity-dependent algae uptake and subsequent carbon and nitrogen metabolisms of two intertidal foraminifera (<i>Ammonia tepida</i> and <i>Haynesina germanica</i>)

2020 ◽  
Vol 17 (13) ◽  
pp. 3723-3732
Author(s):  
Michael Lintner ◽  
Bianca Biedrawa ◽  
Julia Wukovits ◽  
Wolfgang Wanek ◽  
Petra Heinz
Keyword(s):  
Feeding Activity ◽  
N Uptake ◽  
Isotope Ratio Mass Spectrometry ◽  
Trophic Levels ◽  
Food Uptake ◽  
Biomass Turnover ◽  
Feeding Experiments ◽  
C And N ◽  
C And N Cycling ◽  
Marine Protists

Abstract. Benthic foraminifera are abundant marine protists which play an important role in the transfer of energy in the form of organic matter and nutrients to higher trophic levels. Due to their aquatic lifestyle, factors such as water temperature, salinity and pH are key drivers controlling biomass turnover through foraminifera. In this study the influence of salinity on the feeding activity of foraminifera was tested. Two species, Ammonia tepida and Haynesina germanica, were collected from a mudflat in northern Germany (Friedrichskoog) and cultured in the laboratory at 20 ∘C and a light–dark cycle of 16:08 h. A lyophilized algal powder from Dunaliella tertiolecta, which was isotopically enriched with 13C and 15N, was used as a food source. The feeding experiments were carried out at salinity levels of 11, 24 and 37 practical salinity units (PSU) and were terminated after 1, 5 and 14 d. The quantification of isotope incorporation was carried out by isotope ratio mass spectrometry. Ammonia tepida exhibited a 10-fold higher food uptake compared to H. germanica. Furthermore, in A. tepida the food uptake increased with increasing salinity but not in H. germanica. Over time (from 1–5 to 14 d) food C retention increased relative to food N in A. tepida while the opposite was observed for H. germanica. This shows that if the salinity in the German Wadden Sea increases, A. tepida is predicted to exhibit a higher C and N uptake and turnover than H. germanica, with accompanying changes in C and N cycling through the foraminiferal community. The results of this study show how complex and differently food C and N processing of foraminiferal species respond to time and to environmental conditions such as salinity.

scholarly journals Successful Predation of Filamentous Bacteria by a Nanoflagellate Challenges Current Models of Flagellate Bacterivory

2004 ◽  
Vol 70 (1) ◽  
pp. 332-339 ◽  
Author(s):  
Qinglong L. Wu ◽  
Jens Boenigk ◽  
Martin W. Hahn
Keyword(s):  
Prey Size ◽  
Ingestion Rate ◽  
Capture Rate ◽  
Food Concentration ◽  
Filamentous Bacteria ◽  
Selective Predation ◽  
Average Cell ◽  
Feeding Experiments ◽  
Contact Probability ◽  
Food Conditions

ABSTRACT Current models suggest that (i) filamentous bacteria are protected against predation by nanoflagellates, (ii) prey size is positively correlated with prey-predator contact probability, and (iii) contact probability is mainly responsible for size-selective predation by interception-feeding flagellates. We used five strains of filamentous bacteria and one bacterivorous nanoflagellate, Ochromonas sp. strain DS, to test these assumptions. The five strains, including one spirochete and four Betaproteobacteria strains, were isolated by the filtration-acclimatization method. All five strains possess flexible cells, but they differ in average cell length, which ranged from 4.5 to 13.7 μm. High-resolution video microscopy was used to measure contact, capture, and ingestion rates, as well as selectivity of the flagellate feeding. Growth and feeding experiments with satiating and nonsatiating food conditions, as well as experiments including alternative well-edible prey, were performed. In contrast to predictions by current models, the flagellate successfully consumed all the tested filamentous strains. The ingestion rate was negatively correlated with bacterial length. On the other hand, the lengths of the filamentous bacteria were not positively correlated to the contact rate and capture rate but were negatively correlated to ingestion efficiency. In experiments including alternative nonfilamentous prey, the flagellates showed negative selection for filamentous bacteria, which was independent of food concentration and is interpreted as a passive selection. Our observations indicate that (i) size alone is not sufficient to define a refuge for filamentous bacteria from nanoflagellate predation and (ii) for the investigated filamentous bacteria, prey-predator contact probability could be more influenced by factors other than the prey size.

Differentiating in the Community

2017 ◽  
Author(s):  
Mark A. McPeek
Keyword(s):  
Climate Change ◽  
Intraguild Predation ◽  
General Model ◽  
Species Interactions ◽  
Evolutionary Dynamics ◽  
Trophic Levels ◽  
Ecological Differentiation ◽  
Neutral Species ◽  
Biological Communities ◽  
Coexisting Species

This chapter explores the evolutionary dynamics that arise when different types of species mix together in a community either by invasion or by perturbation, as well as community mixing caused by climate change. In particular, it considers the features that promote or retard ecological differentiation of species. The chapter first describes a general model of evolutionary and ecological dynamics in a community before discussing adaptive differentiation at multiple trophic levels. It then examines differentiation of species with identical underlying parameters vs. different underlying parameters, along with intraguild predation and how ecological opportunity evolves within biological communities. It also investigates when neutral species will initially differentiate from one another to convert them into a set of coexisting species, and when differentiated species will initially converge to become ecologically more similar. The chapter shows that, when differentiation occurs, the type of traits underlying species interactions determine the ecological structure of the resulting community.

Ovine fetal leucine kinetics and protein metabolism during decreased oxygen availability

1998 ◽  
Vol 274 (4) ◽  
pp. E618-E626 ◽  
Author(s):  
J. Ross Milley
Keyword(s):  
Protein Synthesis ◽  
Oxygen Consumption ◽  
Fetal Growth ◽  
Oxygen Availability ◽  
Energy Needs ◽  
Leucine Kinetics ◽  
Metabolic Costs ◽  
Pool Model ◽  
Ovine Fetal ◽  
Maternal Hypoxia

The fetus depends on an uninterrupted supply of oxygen to provide energy, not only for basal metabolism but also for the metabolic costs of growth. By curtailing the metabolically expensive processes of protein turnover, the fetus could conserve energy when oxygen availability is limited. Therefore, this investigation was performed to find whether protein synthesis and breakdown are diminished during decreased fetal oxygen availability. Furthermore, if these conditions reduce fetal growth, protein synthesis should be affected more than breakdown so that protein accretion, an important component of fetal growth, also falls. In eight chronically prepared fetal lambs, we compared leucine kinetics (reciprocal pool model) during control conditions with measurements made during maternal hypoxia, a condition that limits fetal oxygen availability. Decreased fetal oxygen availability (−43%; P < 0.001) reduced fetal oxygen consumption (−16%; P < 0.01), as well as both the uptake of leucine across the placenta (−48%; P < 0.001) and its rate of decarboxylation (−30%; P < 0.001). Fetal protein synthesis decreased (−32%; P < 0.001) to a greater extent than proteolysis (−22%; P < 0.001). Consequently, fetal protein accretion, an important component of fetal growth, also decreased (−62%; P < 0.001). We calculate that the reduction in fetal protein synthesis and breakdown, both processes that require intracellular expenditure of ATP, decreased fetal energy needs sufficiently to account for most, if not all, of the decrease measured in fetal oxygen consumption.

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