Influence Of Food Concentration Research Articles

Influence of some ecological factors on the filtration intensity of the oyster (ostrea edulis l.)

The quantitative regularities of filtration of the Black Sea oyster are studied depending on a number of environmental factors. The influence of food concentration on the filtration activity of mollusks is considered. The dependences of the filtration rate on the body weight of oysters for different temperature regimes were determined, and seasonal changes in its intensity in the Kerch Strait and the Donuzlav estuary were characterized. The influence of water salinity on the filtration activity of this type of mollusks has been established.

Influence of food concentration and abiotic parameters on population density growth of the ciliated marine protozoan Euplotes sp. under controlled conditions

High mortality is common when culturing most marine fish larvae, especially during the transition from endogenous to exogenous feeding. In aquaculture, many species of marine fish are not able to survive when only fed enriched rotifers and Artemia spp. nauplii. Ciliates are a potential alternative live food organism for first-feeding larvae, because they can grow to high population densities, accept inert diets, and are natural prey organisms of marine fish larvae. The range of culture parameters to optimize population growth of the ciliate Euplotes sp. are unknown. Five experiments were conducted to determine the effects of food concentration and abiotic factors including salinity, aeration rate, temperature and photoperiod on population growth of the ciliate Euplotes sp. Results indicated the optimal ranges for population growth of Euplotes sp. was a temperature between 26 and 32°C, salinities from 20 and 35 g/L, food (Protein Selco®) concentrations of 250 and 500 mg/million ciliates, absence of or low aeration (8.5 cm3/min) and the photoperiod 0L:24D. Euplotes sp. can tolerate high ammonia and very low dissolved oxygen concentrations, and population growth can occur in these conditions for at least 7 days.

The effect of food concentration and population density of mosquito larvae (Anopheles stephensi, Diptera, Culicidae) on their feeding behavior

The influence of food concentration and population density on the feeding behavior of Anopheles stephensi (Diptera, Culicidae) larvae has been shown experimentally. Lack of food resulted in larvae switching from sweeping the surface film to scraping the substrate off the bottom. The effect of the larval population density was more complex and depended on the food concentration. As a result, the ratio between the larvae keeping to the surface and to the bottom of the vessel was determined by interactions which led to their redistribution between the two trophic niches: the surface film and the bottom substrate. The traits observed ensure plasticity in the use of trophic resources within a water body.

Modelling planktic foraminifer growth and distribution using an ecophysiological multi-species approach

Abstract. We present an eco-physiological model reproducing the growth of eight foraminifer species (Neogloboquadrina pachyderma, Neogloboquadrina incompta, Neogloboquadrina dutertrei, Globigerina bulloides, Globigerinoides ruber, Globigerinoides sacculifer, Globigerinella siphonifera and Orbulina universa). By using the main physiological rates of foraminifers (nutrition, respiration, symbiotic photosynthesis), this model estimates their growth as a function of temperature, light availability, and food concentration. Model parameters are directly derived or calibrated from experimental observations and only the influence of food concentration (estimated via Chlorophyll-a concentration) was calibrated against field observations. Growth rates estimated from the model show positive correlation with observed abundance from plankton net data suggesting close coupling between individual growth and population abundance. This observation was used to directly estimate potential abundance from the model-derived growth. Using satellite data, the model simulate the dominant foraminifer species with a 70.5% efficiency when compared to a data set of 576 field observations worldwide. Using outputs of a biogeochemical model of the global ocean (PISCES) instead of satellite images as forcing variables gives also good results, but with lower efficiency (58.9%). Compared to core tops observations, the model also correctly reproduces the relative worldwide abundance and the diversity of the eight species when using either satellite data either PISCES results. This model allows prediction of the season and water depth at which each species has its maximum abundance potential. This offers promising perspectives for both an improved quantification of paleoceanographic reconstructions and for a better understanding of the foraminiferal role in the marine carbon cycle.

Influence of trophic conditions on biotic interactions under introduction of new species into communities of cladocera

We studied the influence of food concentration on success of introduction of alien species into zooplankton communities. Abundance dynamics of the studied species were simulated under different levels of food supply corresponding to oligo- and eutrophic conditions. Computer-simulated experiments indicated that success of the species introduction was affected by equilibrium food concentration. Species with less equilibrium food concentration were more successful. Among the studied species, more competitive ones were Simocephalus vetulus (large-bodied species) and Ceriodaphnia reticulata (small-bodied species). Indeed, Ceriodaphnia reticulata was the most successful under oligotrophic conditions, and Simocephalus vetulus was so under eutrophic conditions. We suggested that large-bodied species could not compete with the small ones under oligotrophic conditions owing to longer life cycle duration and higher energy requirements at the juvenile stage, especially under food insufficiency. The results of experimental and field studies were analyzed to confirm the success of Ceriodaphnia in competition with larger cladocerans under oligotrophic conditions.

Про вплив деяких екологічних чинників на інтенсивність фільтрації устриці (Ostrea edulis)

Досліджено закономірності живлення фільтрації чорноморської устриці залежно від низки екологічних чинників. Розглянуто вплив концентрації їжі на активність фільтрації молюсків. Визначено залежності швидкості фільтрації від маси тіла устриць за різними температурними режимами та охарактеризовано сезонні зміни її інтенсивності в Керченській протоці та лимані Донузлав. Установлено вплив солоності води на активність фільтрації цього виду молюсків.

Effects of food concentration on clearance rate and energy budget of the Arctic bivalve Hiatella arctica (L) at subzero temperature

The influence of food concentration on clearance rate, respiration, assimilation, and excretion at −1.3 °C was studied on individuals of the bivalve Hiatella arctica (L.) from Young Sound, NE Greenland. Clearance rate, assimilation efficiency, respiration, and excretion rates were determined over a range of food concentrations using the microalga Rhodomonas baltica as food source. Physiological rates were generally low but responded significantly to increased food levels. Clearance rates and assimilation efficiency were reduced at increased food levels, whereas respiration and excretion increased. Assimilation efficiency was generally high, which may be an adaptation to the low food concentration during most of the year in NE Greenland. Low filtration rates limited ingestion rates and resulted in a low maximum assimilation of 3 J h −1. Despite the low food intake, very low food concentrations were required for individual specimens to obtain a positive energy budget. Predicted growth based on rates of assimilation and respiration were compared to published estimates of annual growth in Young Sound. We estimate that 3 weeks of growth in the laboratory under optimal food conditions could match annual growth in situ. We interpret this as evidence that food limitation is the primary impediment to growth in this Arctic population.

Larval development and metamorphosis in Balanus amphitrite Darwin (Cirripedia; Thoracica): significance of food concentration, temperature and nucleic acids

The influence of food concentration ( Chaetoceros calcitrans at 1×10 5 and 2×10 5 cells ml −1) and temperature (20°C and 30°C) on the nucleic acid content of the nauplii and the cyprids of Balanus amphitrite, an acorn barnacle, was evaluated. Food concentration and temperature jointly determined the naupliar instar duration. The total naupliar development period lasted 9–11 days at 20°C and was longer when compared to 5–6 days observed at 30°C. Increase in rearing temperature and food concentration positively influenced the size of the larvae. Food concentration influenced the DNA of III and VI naupliar instars and temperature influenced the DNA of IV and V instar nauplii. The RNA content of IV–VI naupliar instars was also influenced by the rearing temperature. Naupliar experience determined cyprid metamorphosis capability. The RNA content of larvae, that had longer total naupliar duration at 20°C, was considerably less than those raised at 30°C. This difference in RNA content was reflected in the capability of the cyprids to survive at 5°C. The resultant cyprids at 20°C could only successfully metamorphose over 2–4 days, whereas, those at 30°C could do so over 8–16 days. Such differences in the capability to metamorphose will be of critical importance to recruitment and early post-settlement mortality.

Influence of food concentration, temperature and salinity on the larval development ofBalanus amphitrite

Influence of food concentration (0.5, 1 and 2 x 105 cell ml−1 ofSkeletonema costatum), temperature (20 and 30°C) and salinity (15, 25 and 35‰) on the larval development ofBalanus amphitrite (Cirripedia: Thoracica) was examined. The mortality rate at 20°C was lower than at 30°C in general. Increase in food concentration from 0.5 to 1 x 105 cells ml−1 improved the survival rate, but this was not evident when food concentration was increased to 2 x 105 cells ml−1. The results indicate that food availability and temperature jointly determine the energy allocation for metamorphic progress. It was observed that the influence of the tested variables varied with instar. At 20 °C the mean duration of the second instar exceeded 3 d and was much longer than other instar durations. The fourth, fifth and sixth instars and the total naupliar period showed that the effect of different salinities at given food concentrations was negligible at 20°C, while at 30°C there was a marked decrease in duration with increasing salinity.

Food selection by calanoid copepods in response to between‐lake variation in food abundance

SUMMARY1. Food selection experiments were conducted by acclimating calanoid copepods (Eudiaptomus spp.) in suspensions of natural seston and then adding pairs of dual‐labelled (14C/32P) algae. Each feeding trial measured selectivity between a small, high‐quality reference alga, Chlamydomonas reinhardii, and a test alga that differed in size and/or food quality. The influence of food concentration on food selection was tested by using seston from two lakes with contrasting food abundance and by including treatments with filtered lake water ('starved’) and seston diluted with filtered water or enriched with cultured algae.2. Copepods that had been starved or acclimated to natural seston with low food abundance preferred the larger of two labelled algae, regardless of the nutritional quality of the algae. In agreement with the predictions of an optimal diet model, however, copepods that were acclimated to high food conditions discriminated against low‐quality foods, including digestion‐resistant algae and dead algae.3. Selectivity coefficients showed excellent agreement with a previous study involving the same taxa of copepods and labelled algae but in which the copepods had been acclimated to pairs of cultured algae rather than natural seston. Thus, these comparisons emphasize the importance of food availability in modulating copepod selectivity for foods that differ in nutritional quality and suggest that such behaviour occurs in nature.

Influence of food concentration on the physiological energetics and growth ofOstrea edulis larvae

Feeding, respiration and growth rates of oyster (Ostrea edulis L.) larvae reared at five food levels were measured throughout the entire larval period. Energy budgets were derived as a function of alga (Isochrysis galbana Parke) food concentration. Ingestion rate (IR, cells h-1) and oxygen consumption rate (\(V_{O_2 } \), nl h-1) were almost isometric functions of larval size [ash-free dry weight, (AFDW, μg)], characterized by the equations: IR=803.9 AFDW1.13 and\(V_{O_2 } \)=4.85 AFDW1.09. Ingested ration was directly correlated to cell concentration up to a maximum at 200 cells μl-1, with further increases failing to support higher ingestion rates. Likewise, growth rate linearly increased with food ration up to 100 cells μl-1 (max. growth efficiency,K1=25%) and reached a maximum at 200 cells μl-1 (growth rate=5.6 μm d-1), with further increases in food not supporting significantly faster growth. Maintenance ration was 2 to 3% daily dry weight (DW); optimum ration increased during larval development from 5 to 20% DW; maximum ration was 20% DW. During larval rearing, an increasing feeding schedule of 50, 100 and 200 cells μl-1 from Days 0, 5 and 10, respectively, is recommended.

Influence of food concentration on energy balance and growth performance of Venerupis pullastra seed reared in an open-flow system

Seed of the clam Venerupis pullastra were reared with five different rations of Isochrysis galbana: 15, 30, 100, 200 and 300 cells μl −1, in an open-flow system. Physiological parameters such as clearance, ingestion and absorption rates were recorded, and energy balances calculated from these parameters were compared with the long-term growth performance of the seed. High food concentrations inhibited clearance rate but ingestion could not be regulated, being higher with higher food levels. Absorption efficiency decreased moderately at high I. galbana concentrations. Nevertheless, absorption rate was directly correlated with ingesta. Estimated metabolic rate was at a routine level for medium and high food rations and markedly lower at poor food rations. Growth performance was insignificant at 15 cells μl −1 (daily maintenance ration = 2% organic weight), optimal at 100 cells μl −1 ( K 1 = 46%) and maximal at 300 cells μl −1 (growth rate = 11.9 day −1), in agreement with the physiological energetics measurements. Growth rates of V. pullastra seed were similar to those reported for other species, such as Ruditapes philippinarum, regarded as a fast growing member of the Veneridae.

Medium term time acclimation of feeding and digestive enzyme activity in marine copepods: influence of food concentration and copepod species

Medium term time acclimation of feeding and digestive enzyme activity in marine copepods: influence of food concentration and copepod species

The influence of food concentration and temperature on growth and morphological differentiation of blue mussel Mytilus edulis L. larvae

The relationship between growth rate, rate of morphological development, and length of larval life, was examined for larvae of the blue mussel Mytilus edulis L. The larvae were reared at phytoplankton ( Isochrysis galbana, clone T-ISO) concentrations between 0.5 × 10 4 and 30 × 10 4 cells · ml −1 at either 12 or 16°C. Growth rates generally increased with increasing food concentration and were highest at the higher temperature; maximum shell growth rate was ≈ 8 μm · day −1. The number of days required for larvae to develop recognizable eyespots sometimes varied proportionately with changes in growth rate, but often did not; temperature was especially effective at uncoupling rate of growth from rate of morphological development. Maintained in clean glass dishes at 16°C, many eyespotted larvae survived until the end of the study, as long as 8 wk after they first developed eyespots (≈80 days after fertilization). Nearly 30% of those larvae that survived under these conditions eventually metamorphosed in the absence of filamentous substratum, suggesting that metamorphosis can be postponed at least 45 days at 16°C. Food concentration had no effect on 1. (1)the time elapsed between eyespot development and noninduced attachment; 2. (2) the average shell length of individuals that did attach; or 3. (3) the mean size of larvae remaining at the end of the study.

Relationships between fecal pellet production and feeding in the calanoid copepod Boeckella

Study of the influence of food concentration on the number, size and total volume of fecal pellets for two species of Boeckella from Lake Titicaca.The fecal pellet production was also evaluated as an indicator of feeding rates and food selectivity

The influence of food concentration and feeding rate on the gut residence time of Daphnia

The influence of food concentration and feeding rate on the gut residence time of <i>Daphnia</i>

Seasonal variability in the relationship between body length and individual dry weight as related to food abundance and clutch size in two coexisting Daphnia species

Dry weights of individual Daphnia galeata and D. hyalina, which coexist in Lake Con- stance, were determined weekly during a two year investigation. From each sample and each species a length — weight relationship (LWR) was calculated resulting in 54 (65) regression equations based on N = 2466 (3032) in D. galeata (D. hyalina). The constants (Ln(A)) and (B) of the LWRs showed a marked seasonal variability, ranging from Ln(A) = 1.0784 - 2.4740(1.0152 - 2.3860) and B = 2.14 — 4.20(2.11 - 4.15). The seasonal variability of the LWR was estimated with four different models. Condensing the 54 (65) equations into one seasonal cycle resulted in a model with an explained variance of r 1 = 0.873 (0.869). Three more models were established by calculating multiple regres- sions with lake stratification, average fecundity (E), and food concentration as determining variates. Differences in LWRs of the two Daphnia species were significant (p <0.001). As the most useful approximation during the period of stratification, LWRs are recommended for D. galeata: Ln(W) «= (1.5674 + 0.0287*(E)) + Ln(L)*(3.3611 + 0.0111*(E)) as a generalized LWR for an epilimnetic daphnid, and for D. hyalina: Ln(W) = (1.5593 + 0.0613'(E)) + Ln(L)*(3.2709 + 0.0017*(E)) as LWR for a daphnid which migrates diurnally between epi and hypolimnion. The explained variance of this model is r2 = 0.843 (0.826). The influence of food concentration in the epilimnion on LWRs was found to be significant on Ln(A) but not on (B).