Effect of salinity and food concentration on competition between Brachionus plicatilis Müller, 1786 and Brachionus calyciflorus Pallas, 1776 (Rotifera)

2020 ◽  
Vol 71 (4) ◽  
pp. 493
Author(s):  
N. S. Ferrando ◽  
S. Nandini ◽  
M. C. Claps ◽  
S. S. S. Sarma
Keyword(s):  
Brachionus Plicatilis ◽  
Natural Populations ◽  
Food Concentration ◽  
Brachionus Calyciflorus ◽  
Food Density ◽  
Food Concentrations ◽  
Salinity Levels ◽  
Planktonic Rotifers ◽  
Salado River ◽  
Pampean Shallow Lakes

Natural populations of planktonic rotifers are affected by salinity and food density, among other stressors. Moreover, competition among congeneric species limits the abundance of certain rotifers in ecosystems without spatial heterogeneity and environmental fluctuations. We isolated Brachionus plicatilis and Brachionus calyciflorus from Salado River basin waterbodies and studied the demographic characteristics and competition between them at three salinity levels (0.75, 1.75 and 2.75gL–1 NaCl) and at two food concentrations (0.1×106 and 0.5×106 cells mL–1 Chlorella vulgaris). The lowest salinity level proved to be unfavourable for the population growth of B. plicatilis, but at higher salinity levels the growth was similar to that of controls (without competition), even in the presence of the competitor and at either food concentration. By contrast, the competitor almost always decreased the density of B. calyciflorus. Salinity greatly affected the peak density of B. plicatilis, whereas the effects of salinity and competition on B. calyciflorus were similar. Biomass was inversely related to salinity for both species, and was significantly affected by competition in B. plicatilis. These results show that B. calyciflorus is more adversely affected than B. plicatilis by competition and high salinity, and explain why both species can coexist in eutrophic saline lowland rivers and pampean shallow lakes.

scholarly journals Does resource availability influence the vital rates of the tropical copepod Apocyclops royi (Lindberg, 1940) under changing salinities?

2020 ◽  
Vol 42 (4) ◽  
pp. 467-478 ◽  
Author(s):  
Hans Van Someren Gréve ◽  
Per Meyer Jepsen ◽  
Benni Winding Hansen
Keyword(s):  
Production Rate ◽  
Food Availability ◽  
Egg Production ◽  
Food Concentration ◽  
Threshold Concentration ◽  
Cyclopoid Copepod ◽  
Vital Rates ◽  
Food Concentrations ◽  
Salinity Levels ◽  
Egg Production Rate

Abstract The physiology of invertebrates inhabiting many coastal ecosystems is challenged by strong temporal fluctuations in salinity. We investigated how food availability influences vital rates in the tropical cyclopoid copepod Apocyclops royi subjected to different salinities (5–32 PSU). We hypothesized that (i) mortality decreases and egg production rate increases with food availability; (ii) under suboptimal salinity, mortality increases and the egg production rate is reduced and (iii) the threshold concentration for egg production (the lowest food concentration where egg production is initiated) shifts to higher food concentrations when challenged by salinity. Surprisingly, A. royi survived, ingested food and produced eggs at all tested salinities. Mortality rate was, however, dependent on salinity level, but not on food availability. Mortality increased (~12% h−1) during short-term (1 h) salinity acclimatization to 5 PSU and during the following 24-h incubations (~5% d−1) compared with higher salinities. Feeding and egg production rates increased with food availability up to an optimum at all salinity levels, with no effect of salinity on the lowest food concentration initiating egg production. This reveals a high-salinity tolerance by A. royi and may partly explain why this particular copepod is so successful compared with its congeners in occupying extreme habitats.

scholarly journals Inducible morphological defense in Daphnia pulex: food quantity effects revised

2020 ◽  
Author(s):  
Sandra Klintworth ◽  
Eric von Elert
Keyword(s):  
Chemical Cues ◽  
Daphnia Pulex ◽  
Food Concentration ◽  
Bacterial Degradation ◽  
Inducible Defenses ◽  
Chemical Cue ◽  
High Food ◽  
Food Quantity ◽  
Morphological Defense ◽  
Food Concentrations

Abstract In aquatic systems, organisms largely rely on chemical cues to perceive information about the presence of predators or prey. Daphnia recognize the presence of the predatory larvae of Chaoborus via a chemical cue, emitted by the larvae, a so-called kairomone. Upon recognition, neckteeth, an alteration of the carapace, are induced in Daphnia that reduce predation rates of Chaoborus. Neckteeth induction was often reported to entail costs. In a previous study, food quantity affected the level of neckteeth induction, with stronger neckteeth induction at low food concentrations and weak induction at high food concentrations. However, reducing neckteeth induction at high food quantities seems to be maladaptive and not in accordance with the concept that inducible defenses are associated with costs. Here, we hypothesized that weaker neckteeth induction at high food concentrations is caused by increased bacterial degradation of the kairomone. More specifically, we assume that higher algal food concentration is associated with higher bacterial abundances, which degrade the kairomone during the experiment. We tested our hypothesis by treating food algae with antibiotics before providing them as food to Daphnia. Antibiotics reduced bacterial abundances at high and low food concentrations. Reduced bacterial abundances at high food concentrations led to the same level of neckteeth induction as at low food concentrations. A linear regression revealed a significant correlation of neckteeth induction to bacterial abundances. We therefore conclude that differences in neckteeth induction at different food concentrations are not caused by the food quantity effects but by differences in bacterial degradation of the kairomone.

scholarly journals A modelling study of the influence of environment and food supply on survival of Crassostrea gigas larvae

2004 ◽  
Vol 61 (4) ◽  
pp. 596-616 ◽  
Author(s):  
Eileen E Hofmann ◽  
Eric N Powell ◽  
Eleanor A Bochenek ◽  
John M Klinck
Keyword(s):  
Genetic Variation ◽  
Food Quality ◽  
Egg Quality ◽  
Larval Growth ◽  
High Growth ◽  
Growth Efficiency ◽  
Food Concentration ◽  
Larval Survival ◽  
Food Concentrations ◽  
Food Content

Abstract A biochemically based model was developed to simulate the growth, development, and metamorphosis of larvae of the Pacific oyster (Crassostrea gigas). The unique characteristics of the model are that it: (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate, and ash content; (2) tracks weight separately from length to follow larval condition; and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for filtration, ingestion, and respiration, which determine larval growth rate, and processes controlling larval mortality and metamorphosis. Changes in larval tissue composition occur as the larva grows and in response to the biochemical composition of the food. Simulations of larval growth indicate that departures of temperature, salinity, or food content from optimum levels reduce larval cohort survival, either because of metabolic constraints that result in death, unsuccessful metamorphosis, or increased predation resulting from increased larval lifespan. Temperatures and salinities near optimal values improve larval survival at low food concentration by increasing ingestion rate or growth efficiency. Also, survival at a given food concentration can vary widely depending on food composition, which determines food quality. The simulations suggest that the ratio of carbohydrate + lipid-to-protein may best describe the overall food quality, with optimal food compositions being characterized by ratios near 1.2 to 1.4 over a range of food concentrations. In contrast, food compositions containing too much or too little protein reduce larval survival, even at saturating food concentrations. In simulations emphasizing genetic variability within the cohort, larvae with high growth efficiency originating from large eggs out-perform other egg quality–growth efficiency combinations over a wide range of temperature, salinity, and food contents. As a consequence, suboptimal temperature, salinity, or food content compresses genetic variation by uniformly favouring larvae from large eggs with a high growth efficiency. However, the larval survival obtained from simulations that use a range of food qualities is representative of a much broader range of genetic types. Thus, the simulations support the supposition that food quality is an important variable controlling the survival and genetic variability of C. gigas larval cohorts.

Functional response to Daphnia carinata King when feeding on the filamentous diatom Melosira granulata

1993 ◽  
Vol 44 (5) ◽  
pp. 761 ◽  
Author(s):  
CR King ◽  
RJ Shiel
Keyword(s):  
Functional Response ◽  
Food Item ◽  
Ingestion Rate ◽  
Dry Weight ◽  
Food Concentration ◽  
Daphnia Carinata ◽  
Food Concentrations

The functional response of D. carinata feeding on M. granulata was determined from laboratory trials conducted at 20-22�C, using a range of food concentrations (F) from 0.14 to 33.8�g (dry weight) mL-1. The functional response could be described by an lvlev model: I (ingestion rate, ng �g-1 h-1) = 200 - 205 × exp (- 0.036 × F). The ingestion rate at the highest food concentration (33.8 �g mL-1) was 140 ng �g-1 h-1, and there was no evidence to suggest that M. granulata either interfered with feeding at high densities or was a difficult food item for D. carinata to handle.

Direct detection of digestive enzymes in planktonic rotifers using enzyme-labelled fluorescence (ELF)

2005 ◽  
Vol 56 (2) ◽  
pp. 189 ◽  
Author(s):  
M. Štrojsová ◽  
J. Vrba
Keyword(s):  
Enzyme Assay ◽  
Direct Detection ◽  
Feeding Activity ◽  
Life Stage ◽  
Natural Populations ◽  
Trend Detection ◽  
Additional Information ◽  
New Information ◽  
Planktonic Rotifers

A novel enzyme-labelled-fluorescence (ELF) method was applied to natural populations of planktonic rotifers from a eutrophic reservoir. Direct visualisation of rotifers by this new method provided new information about enzymatic activities in situ, including detection and location of enzyme activities. Three fluorogenic substrates were used for the enzyme assay in concentrated (20–60×) samples of the rotifers. After a short (1–3 h) incubation in test tubes, samples were filtered and the rotifers on polycarbonate filters were examined using an epifluorescence microscope. Activity of phosphatases, β-N-acetylhexosaminidases and lipases were detected in some species that were regularly inspected during two seasons – most frequently in the stomach area, at the corona and, less often, in the mastax area. The results suggest that most of the detected enzymes are connected with the digestive tracts of rotifers. Also, autofluorescence of chlorophyll a enabled visualisation of the digestive tracts of the rotifers and provided additional information on the food (phytoplankton). Enzyme expression did not show any clear seasonal trend. Detection of specific enzymes varied considerably between species of rotifers and between individuals. This variability could be a result of change of feeding behaviour of rotifers in the concentrated samples and also could reflect individual differences among the rotifers in a population, such as feeding activity, age or life stage.

Larval development and metamorphosis of Balanus albicostatus (Cirripedia: Thoracica); implications of temperature, food concentration and energetics

2006 ◽  
Vol 86 (2) ◽  
pp. 335-343 ◽  
Author(s):  
Dattesh Desai ◽  
Lidita Khandeparker ◽  
Yoshihisa Shirayama
Keyword(s):  
Organic Carbon ◽  
Nitrogen Content ◽  
Food Concentration ◽  
Carbon And Nitrogen ◽  
Food Concentrations ◽  
Development Duration ◽  
Influence Of Food ◽  
Effect Of Food ◽  
Naupliar Development ◽  
Carbon And Nitrogen Content

The influence of food concentrations (0.5, 1 and 2×105 cells ml−1) and temperatures (20 and 30°C) on the survival, development, organic carbon and nitrogen content of Balanus albicostatus larvae was evaluated. The effect of food concentration on the subsequent ageing and metamorphosis of cypris larva was also determined. At lower food concentration and temperature, naupliar development duration was prolonged and the rate of metamorphosis of nauplius to cyprid was low. The rearing food concentration affected organic carbon and nitrogen content of the nauplii, which was also reflected in non-feeding cyprids. A decrease in the carbon content was observed with cyprid ageing at 5°C. Metamorphosis was higher in 8-d aged cyprids when compared to 2-d aged cyprids, and was positively influenced by the natural biofilm.

Effects of food concentration on the life table demography and morphology of three Keratella quadrata morphotypes

2018 ◽  
Vol 54 ◽  
pp. 16 ◽  
Author(s):  
Ya-Li Ge ◽  
Rong Zhan ◽  
Jin-Hang Yu ◽  
Yi-Long Xi ◽  
Jie Ma ◽  
...  
Keyword(s):  
Life Table ◽  
Scenedesmus Obliquus ◽  
Morphological Characteristics ◽  
Intrinsic Rate ◽  
Food Concentration ◽  
High Energy ◽  
Abnormal Development ◽  
Natural Environments ◽  
Food Concentrations ◽  
Keratella Quadrata

Keratella quadrata with two (2PS), one (1PS) and none posteolateral (0PS) spines were cultured under four food levels (0.75 × 106, 1.5 × 106, 3.0 × 106 and 6.0 × 106 cells·mL−1 of Scenedesmus obliquus) to test the differences in the life table demography and the morphological characteristics among these three morphotypes. The results showed that each K. quadrata morphotype could produce 2PS, 1PS and 0PS offsprings. The frequencies of 0PS were extremely low (<5%) and could be considered as a small probability event, suggesting that the 0PS morphotype might be an abnormal status. The following life table demographic tests suggested that 0PS morphotype had a relatively lower intrinsic rate of population growth at high food concentrations and a relatively lower average lifespan, in comparison to 2PS rotifers. These results further supported that the 0PS K. quadrata might be an abnormal development. Along with the elevating food concentration, 1PS morphotype reproduced more 2PS offsprings, suggesting that high energy input might be helpful to grow more posterolateral spines. However, in response to the increasing food concentration, 0PS rotifers produced more 1PS offsprings. The underlying mechanisms required further investigations. The posterolateral spine length of offsprings of 0PS K. quadrata was significantly longer than those of 2PS and 1PS rotifer parents at the four food concentrations, which probably help the offsprings of 0PS rotifer parents to survive in natural environments, since long and more posterolateral spines offer rotifers high ability to compete with other rotifers and cladocerans for food or to resist predators.

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