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Christopher M Pearce - One of the best experts on this subject based on the ideXlab platform.

  • interactive effects of stocking density and algal feed ration on growth survival and Ingestion Rate of larval geoduck clams
    North American Journal of Aquaculture, 2014
    Co-Authors: Christopher M Pearce, Robert Marshall, Scott R Mckinley
    Abstract:

    AbstractThe combined effects of initial stocking density (2, 5, 10 individuals [inds]/mL) and feed ration (5×103, 20×103, 40×103, 100×103 cells·ind−1·d−1) on growth, survival, and Ingestion Rate of larval geoduck clams Panopea generosa fed Isochrysis sp. (Tahitian strain, TISO clone) were assessed. All three measurements were significantly affected by stocking density, ration, and their interaction. Growth Rate ranged from 2.15 to 3.85 μm/d in the various treatments. It increased with stocking density at 5×103 cells·ind−1·d−1, was significantly higher at 5 than at 2 inds/mL at 20×103 cells·ind−1·d−1, and was significantly higher at 2 and 5 than at 10 inds/mL at 40×103 and 100×103 cells·ind−1·d−1. Growth Rate increased with increasing ration up to 40×103 cells·ind−1·d−1 at 2 and 5 inds/mL, but decreased with increasing ration at 10 inds/mL. Percent survival over the experiment duration (23 d) ranged from 7% to 56% in the various treatments and generally decreased with increasing stocking density. There was...

  • Ingestion Rate absorption efficiency oxygen consumption and fecal production in green sea urchins strongylocentrotus droebachiensis fed waste from sablefish anoplopoma fimbria culture
    Aquaculture, 2014
    Co-Authors: Lindsay C Orr, Daniel L Curtis, Stephen F Cross, Helen Gurneysmith, Alynn Shanks, Christopher M Pearce
    Abstract:

    Abstract The ability of the green sea urchin (Strongylocentrotus droebachiensis) to consume and subsequently reduce the organic content of sablefish (Anoplopoma fimbria) culture waste was assessed and properties influencing the dispersal of fecal pellets egested by the sea urchins were quantified in laboratory trials. Ingestion Rate, absorption efficiency, and oxygen uptake in sea urchins and the shape, size, and settling velocity of fecal pellets were determined for individuals fed sablefish waste or a natural control diet (giant kelp, Macrocystis pyrifera). Results showed that S. droebachiensis consumes sablefish waste at a dry weight Ingestion Rate of 0.43 ± 0.039 g individual− 1 d− 1 and absorbs 40 ± 4.84% (mean ± SE) of the organic material ingested, with no significant (P

  • effects of diet and temperature on Ingestion absorption assimilation gonad yield and gonad quality of the purple sea urchin strongylocentrotus purpuratus
    Aquaculture, 2011
    Co-Authors: Christopher M Pearce, Kalam A Azad, Scott R Mckinley
    Abstract:

    Abstract Sea-urchin Ingestion Rate, absorption, gonad yield, and gonad quality can be influenced by a variety of factors, including food quantity, food quality, and various environmental conditions. We examined the combined effects of two factors (diet and temperature) on Ingestion Rate, absorption, assimilation efficiency, and gonad enhancement of the purple sea urchin, Strongylocentrotus purpuratus , over a 12-week period. Four diets [three kelp species ( Macrocystis integrifolia , Nereocystis luetkeana , and Saccharina latissima ) and one prepared feed] and three temperatures (8.0 ± 0.4, 12.3 ± 0.3, and 16.2 ± 0.4 °C: mean ± SD) were tested in a completely crossed factorial design. Ingestion Rate, gravimetric absorption, and assimilation efficiency of urchins fed the various diets were calculated at weeks 6 and 12. In addition, a number of gonad attributes were quantified at the beginning and end of the experiment including wet weight, percent water content, gonad index, texture, firmness, colour, and flavour. Ingestion Rate, gravimetric absorption, and assimilation efficiency were generally significantly affected by both temperature and diet. Wet-weight Ingestion Rates were significantly higher with the three kelp treatments than with the prepared diet at both weeks 6 and 12. This particular dietary difference was not apparent, however, when Ingestion Rates were expressed on a dry-weight basis. The highest Ingestion Rates were recorded for animals held at 12 °C at week 6 and at 16 °C at week 12. Absorption Rates and assimilation efficiencies were significantly higher at 16 °C than at 8 °C at week 6 and significantly higher at 16 °C than at the other two temperatures at week 12. Final gonad weight and gonad index were significantly greater in urchins fed the prepared diet than in those fed any of the three kelp species, with little difference among the kelp treatments. Final gonad weight was significantly affected by temperature, but this effect was dependent on diet; temperature had little impact on gonad weight (and index) in the three kelp treatments, but 12 and 16 °C produced significantly heavier gonads than 8 °C for urchins fed the prepared diet. Gonads of urchins fed kelps had more (significantly more in the case of M. integrifolia and N. luetkeana ) water than those fed the prepared diet. Gonad colour, texture, and firmness were generally not significantly affected by temperature, diet, or the interaction of these two factors. Gonad flavour was generally (sometimes significantly) better in urchins fed the prepared diet than in those fed the three kelp species. Taking all the measured variables into consideration, we recommend that culture operations utilise a prepared diet at 12 °C to optimise gonad production of S. purpuratus .

Johannes-günter Kohl - One of the best experts on this subject based on the ideXlab platform.

  • Does the toxic effect of Microcystis aeruginosa on Daphnia galeata depend on microcystin Ingestion Rate
    Archiv Fur Hydrobiologie, 1999
    Co-Authors: Thomas Rohrlack, Manfred Henning, Johannes-günter Kohl
    Abstract:

    The aim of this study was to test the hypothesis that toxicity of Microcystis aeruginosa to Daphnia galeata can be explained by microcystins. For that purpose, the relationship between the strength of toxic effect and microcystin Ingestion Rate (amount of microcystins ingested per time with the respective food) by the animals was analysed. Of the tested Microcystis strains, only those containing microcystins, were poisonous to daphnids. It was, furthermore, shown that toxicity was closely related to the microcystin Ingestion Rate. Thus, the results support the hypothesis that microcystins are the most likely cause of daphnid poisoning, and they also emphasise that the toxicity of a Microcystis strain depends on both, the cellular microcystin content and the Rate with which it is ingested by the animals. The data also demonstRate that the feeding activity of D. galeata is not correlated to the microcystin content of the Microcystis culture fed. This may indicate that the strain-specific differences in feeding on M. aeruginosa are not due to the microcystins. As toxicity was also observed when colony-forming strains with a mucilage sheath were offered, it seems likely that microcystin release in the gut is not actually hindered by mucilage and that toxicity can occur even under natural conditions.

  • Mechanisms of the inhibitory effect of the cyanobacterium Microcystis aeruginosa on Daphnia galeata's Ingestion Rate
    Journal of Plankton Research, 1999
    Co-Authors: Thomas Rohrlack, Manfred Henning, Johannes-günter Kohl
    Abstract:

    The possible effects of five Microcystis aeruginosa strains (two unicellular and three colony forming) on the filtering and feeding behavior of Daphnia galeata were investigated to clarify the mechanisms of the inhibitory effect on the Ingestion Rate of the animals. Of the tested cyanobacterial strains, three inhibited Daphnia's food Ingestion. This was primarily caused by affecting the frequency and food transport efficiency of the maxillary contractions. As a result, Daphnia's swallowing Rate, and in one case the amount of food contained in the swallowed boluses, were lower than in suspen- sions of well-ingestible food sources. In contrast, there is no indication that Microcystis can influence thoracic appendage beat or rejection Rate. It is likely that colony-forming and unicellular strains can affect the Ingestion process due to different factors. The mucilage of the colony-forming Microcystis strains HUB-W75 and HUB-W334 possibly produced a mechanical hindrance of the maxillules, which resulted in an abnormal movement and consequently in the inhibitory effects described above. This was related to the sugar composition of the mucilage polysaccharides, but not to the cellular micro- cystin content or occurrence of accompanying bacteria. The mucilage-lacking strain HUB 5-2-4, however, must contain another factor which interfered with the maxillules' movement in an unknown way.

  • role of microcystins in poisoning and food Ingestion inhibition of daphnia galeata caused by the cyanobacterium microcystis aeruginosa
    Applied and Environmental Microbiology, 1999
    Co-Authors: Thomas Rohrlack, Elke Dittmann, Thomas Börner, Manfred Henning, Johannes-günter Kohl
    Abstract:

    Several species of cyanobacteria, including the bloom-forming freshwater species Microcystis aeruginosa, are able to produce several variants of microcystin, the most common cyanotoxin, which has been implicated in livestock poisoning and human poisoning (4, 5, 23). Recently, it was shown that these small cyclic peptides are synthesized nonribosomally by peptide synthetases (8). Numerous studies have been carried out in order to determine the ecological significance of the microcystins. The results obtained, however, are inconsistent (11). One possible function of microcystins is that they play a role in the defense of M. aeruginosa cells against zooplankton grazing. This hypothesis is supported by the observation that exposure to Microcystis cells reduces the life span of daphnids (3, 10, 13, 18, 24). However, the problem seems to be more complex. The data of Jungmann (13) and Jungmann and Benndorf (14), for example, suggested that an unidentified metabolite of Microcystis sp. rather than microcystins was responsible for toxicity to Daphnia. Moreover, Nizan et al. (24) found no correlation between acute toxicity of various M. aeruginosa strains to daphnids and their quantitative microcystin contents. In other cases, daphnids could feed on microcystin-containing M. aeruginosa without suffering any harmful effects (22). Experiments on Microcystis toxicity have usually been performed by comparing strains which differ in microcystin content. However, other strain-specific properties could be the source of the striking variation in the results obtained in different investigations. For example, M. aeruginosa strains differ in their content of potential toxic oligopeptides (25), which could strengthen or mask a toxic effect of microcystins. Also strain-specific differences in ingestibility of M. aeruginosa cells by daphnids may influence the dose of an endotoxin, which is determined by the Ingestion Rate (amount of food taken in per time unit) and by the toxin content of the cells. Indeed, the Ingestion Rate of daphnids depends to a large extent on the M. aeruginosa strain offered as food. Some strains affect the Ingestion Rate of the animals, whereas others do not (10, 12, 15, 18, 19). Some authors (12, 19) have hypothesized that a perceptible factor (“bad taste”) is responsible for this effect. However, the possibility that microcystins themselves are involved in the inhibition of Ingestion cannot be ruled out. The experiments described in this paper were designed to study the role of microcystins in the effect of M. aeruginosa on Daphnia galeata; both Microcystis toxicity and strain-dependent inhibition of Ingestion were studied. To do this, we compared an M. aeruginosa PCC7806 mutant which was genetically engineered to knock out the production of microcystins with the microcystin-synthesizing wild-type strain. The two variants of strain PCC7806 used have the same genotype except that the mutant (mcy−) cells have an insertional mutation in a microcystin synthetase gene (8).

Thomas Rohrlack - One of the best experts on this subject based on the ideXlab platform.

  • effects of cell bound microcystins on survival and feeding of daphnia spp
    Applied and Environmental Microbiology, 2001
    Co-Authors: Thomas Rohrlack, Elke Dittmann, Thomas Börner, Kirsten Christoffersen
    Abstract:

    The influence of cell-bound microcystins on the survival time and feeding Rates of six Daphnia clones belonging to five common species was studied. To do this, the effects of the microcystin-producing Microcystis strain PCC7806 and its mutant, which has been genetically engineered to knock out microcystin synthesis, were compared. Additionally, the relationship between microcystin Ingestion Rate by the Daphnia clones and Daphnia survival time was analyzed. Microcystins ingested with Microcystis cells were poisonous to all Daphnia clones tested. The median survival time of the animals was closely correlated to their microcystin Ingestion Rate. It was therefore suggested that differences in survival among Daphnia clones were due to variations in microcystin intake rather than due to differences in susceptibility to the toxins. The correlation between median survival time and microcystin Ingestion Rate could be described by a reciprocal power function. Feeding experiments showed that, independent of the occurrence of microcystins, cells of wild-type PCC7806 and its mutant are able to inhibit the feeding activity of Daphnia. Both variants of PCC7806 were thus ingested at low Rates. In summary, our findings strongly suggest that (i) sensitivity to the toxic effect of cell-bound microcystins is typical for Daphnia spp., (ii) Daphnia spp. and clones may have a comparable sensitivity to microcystins ingested with food particles, (iii) Daphnia spp. may be unable to distinguish between microcystin-producing and -lacking cells, and (iv) the strength of the toxic effect can be predicted from the microcystin Ingestion Rate of the animals.

  • Does the toxic effect of Microcystis aeruginosa on Daphnia galeata depend on microcystin Ingestion Rate
    Archiv Fur Hydrobiologie, 1999
    Co-Authors: Thomas Rohrlack, Manfred Henning, Johannes-günter Kohl
    Abstract:

    The aim of this study was to test the hypothesis that toxicity of Microcystis aeruginosa to Daphnia galeata can be explained by microcystins. For that purpose, the relationship between the strength of toxic effect and microcystin Ingestion Rate (amount of microcystins ingested per time with the respective food) by the animals was analysed. Of the tested Microcystis strains, only those containing microcystins, were poisonous to daphnids. It was, furthermore, shown that toxicity was closely related to the microcystin Ingestion Rate. Thus, the results support the hypothesis that microcystins are the most likely cause of daphnid poisoning, and they also emphasise that the toxicity of a Microcystis strain depends on both, the cellular microcystin content and the Rate with which it is ingested by the animals. The data also demonstRate that the feeding activity of D. galeata is not correlated to the microcystin content of the Microcystis culture fed. This may indicate that the strain-specific differences in feeding on M. aeruginosa are not due to the microcystins. As toxicity was also observed when colony-forming strains with a mucilage sheath were offered, it seems likely that microcystin release in the gut is not actually hindered by mucilage and that toxicity can occur even under natural conditions.

  • Mechanisms of the inhibitory effect of the cyanobacterium Microcystis aeruginosa on Daphnia galeata's Ingestion Rate
    Journal of Plankton Research, 1999
    Co-Authors: Thomas Rohrlack, Manfred Henning, Johannes-günter Kohl
    Abstract:

    The possible effects of five Microcystis aeruginosa strains (two unicellular and three colony forming) on the filtering and feeding behavior of Daphnia galeata were investigated to clarify the mechanisms of the inhibitory effect on the Ingestion Rate of the animals. Of the tested cyanobacterial strains, three inhibited Daphnia's food Ingestion. This was primarily caused by affecting the frequency and food transport efficiency of the maxillary contractions. As a result, Daphnia's swallowing Rate, and in one case the amount of food contained in the swallowed boluses, were lower than in suspen- sions of well-ingestible food sources. In contrast, there is no indication that Microcystis can influence thoracic appendage beat or rejection Rate. It is likely that colony-forming and unicellular strains can affect the Ingestion process due to different factors. The mucilage of the colony-forming Microcystis strains HUB-W75 and HUB-W334 possibly produced a mechanical hindrance of the maxillules, which resulted in an abnormal movement and consequently in the inhibitory effects described above. This was related to the sugar composition of the mucilage polysaccharides, but not to the cellular micro- cystin content or occurrence of accompanying bacteria. The mucilage-lacking strain HUB 5-2-4, however, must contain another factor which interfered with the maxillules' movement in an unknown way.

  • role of microcystins in poisoning and food Ingestion inhibition of daphnia galeata caused by the cyanobacterium microcystis aeruginosa
    Applied and Environmental Microbiology, 1999
    Co-Authors: Thomas Rohrlack, Elke Dittmann, Thomas Börner, Manfred Henning, Johannes-günter Kohl
    Abstract:

    Several species of cyanobacteria, including the bloom-forming freshwater species Microcystis aeruginosa, are able to produce several variants of microcystin, the most common cyanotoxin, which has been implicated in livestock poisoning and human poisoning (4, 5, 23). Recently, it was shown that these small cyclic peptides are synthesized nonribosomally by peptide synthetases (8). Numerous studies have been carried out in order to determine the ecological significance of the microcystins. The results obtained, however, are inconsistent (11). One possible function of microcystins is that they play a role in the defense of M. aeruginosa cells against zooplankton grazing. This hypothesis is supported by the observation that exposure to Microcystis cells reduces the life span of daphnids (3, 10, 13, 18, 24). However, the problem seems to be more complex. The data of Jungmann (13) and Jungmann and Benndorf (14), for example, suggested that an unidentified metabolite of Microcystis sp. rather than microcystins was responsible for toxicity to Daphnia. Moreover, Nizan et al. (24) found no correlation between acute toxicity of various M. aeruginosa strains to daphnids and their quantitative microcystin contents. In other cases, daphnids could feed on microcystin-containing M. aeruginosa without suffering any harmful effects (22). Experiments on Microcystis toxicity have usually been performed by comparing strains which differ in microcystin content. However, other strain-specific properties could be the source of the striking variation in the results obtained in different investigations. For example, M. aeruginosa strains differ in their content of potential toxic oligopeptides (25), which could strengthen or mask a toxic effect of microcystins. Also strain-specific differences in ingestibility of M. aeruginosa cells by daphnids may influence the dose of an endotoxin, which is determined by the Ingestion Rate (amount of food taken in per time unit) and by the toxin content of the cells. Indeed, the Ingestion Rate of daphnids depends to a large extent on the M. aeruginosa strain offered as food. Some strains affect the Ingestion Rate of the animals, whereas others do not (10, 12, 15, 18, 19). Some authors (12, 19) have hypothesized that a perceptible factor (“bad taste”) is responsible for this effect. However, the possibility that microcystins themselves are involved in the inhibition of Ingestion cannot be ruled out. The experiments described in this paper were designed to study the role of microcystins in the effect of M. aeruginosa on Daphnia galeata; both Microcystis toxicity and strain-dependent inhibition of Ingestion were studied. To do this, we compared an M. aeruginosa PCC7806 mutant which was genetically engineered to knock out the production of microcystins with the microcystin-synthesizing wild-type strain. The two variants of strain PCC7806 used have the same genotype except that the mutant (mcy−) cells have an insertional mutation in a microcystin synthetase gene (8).

Pierre-yves Pascal - One of the best experts on this subject based on the ideXlab platform.

  • The use of stable isotopes to measure the Ingestion Rate of 1 potentially toxic benthic dinoflagellates by harpacticoid copepods
    Journal of Experimental Marine Biology and Ecology, 2020
    Co-Authors: Aurélie Boisnoir, Anne-sophie Pavaux, Nikolaos Schizas, Sophie Marro, Thierry Blasco, Rodolphe Lemée, Pierre-yves Pascal
    Abstract:

    Phycotoxins synthesized by benthic dinoflagellates are known to bioaccumulate in macrofauna and hence represent a risk for human health. However, the presence of toxins synthesized by benthic dinoflagellates in smaller marine organisms than macrofauna has not been considered despite the fact that such small organisms have an important ecological role in the benthic food web. This present study quantified, for the first time, the trophic relationship between benthic dinoflagellates and meiofauna by using stable isotope enriched dinoflagellates during Ingestion experiments. Results showed that harpacticoid copepods were not able to discriminate, during Ingestion, between the potentially toxic cells of Ostreopsis cf. ovata and the non-toxic cells of Amphidinium cf. carterae, even when another food resource, such as diatoms (e.g. Odontella sp.), was provided (Kruskal Wallis test, p > 0.05).

  • Influence of environment factors on bacterial Ingestion Rate of the deposit-feeder Hydrobia ulvae and comparison with meiofauna
    Journal of Sea Research, 2008
    Co-Authors: Pierre-yves Pascal, Christine Dupuy, Pierre Richard, Anne-gaelle Haubois, Nathalie Niquil
    Abstract:

    Deposit feeders are able to process a considerable volume of sediment, containing large quantities of associated bacteria. However, conclusions concerning the trophic role played by benthic bacteria in marine sediments are still not fully elucidated. This study deals with bacterivory by the gastropod Hydrobia ulvae, one of the most abundant deposit-feeding species in intertidal mudflats in Western Europe. Ingestion Rates of bacteria were determined during grazing experiments using 15N pre-enriched bacteria. Grazing experiments were performed in order to measure effects of abiotic (temperature, salinity and luminosity) and biotic (bacterial and algal abundances) factors on Ingestion Rates of bacteria by H. ulvae of an intertidal mudflat (Brouage, Marennes-Oleron, France). The mean Ingestion Rate of bacteria by H. ulvae was 1149 ng C ind− 1 h− 1. The general trend showed a temperature effect with an optimum around 30 °C, and the assimilation Rate was significantly lower at 5 °C. Bacterial assimilation did not significantly differ between salinity 18 and salinity 31. Ingestion was the same in light and in dark conditions. Results were compared with those of other grazing experiments conducted simultaneously in similar conditions with two other grazers with different size and feeding modes: the foraminifera Ammonia tepida and a nematode community from the superficial sediment of the Brouage mudflat. H. ulvae and nematodes presented a feeding behavior less influenced by environmental changes than A. tepida. H. ulvae ingested bacteria at a higher Rate than smaller meiofaunal grazers and seemed to have a lower ability to selectively ingest diatoms than meiofaunal grazers.

Diana Chilmawati - One of the best experts on this subject based on the ideXlab platform.

  • pengaruh pemberian pakan alami chaetoceros calcitrans dan isochrysis galbana dengan dosis yang berbeda terhadap Ingestion Rate dan peforma pertumbuhan oithona sp
    2016
    Co-Authors: Rukun Dian Lestari Sihombing, Suminto Suminto, Diana Chilmawati
    Abstract:

    Oithona sp. adalah salah satu dari jenis copepoda yang sering diberikan sebagai pakan alami di dalam pembenihan ikan dan udang. Kajian tentang pemanfaatan pakan alami untuk budidaya Oithona sp. baik secara volume terbatas maupun massal belum banyak dilakukan. Penelitian ini bertujuan untuk mengetahui pengaruh pakan alami (Chaetoceros calcitrans dan Isochrysis galbana) dengan dosis yang berbeda terhadap nilai Ingestion Rate dan peforma pertumbuhan Oithona sp. Pengaruh pakan alami (Chaetoceros calcitrans dan Isochrysis galbana) dengan dosis yang berbeda terhadap nilai Ingestion Rate dan peforma pertumbuhan telah dilakukan pengkajian pada penelitian ini. Metode eksperimen telah digunakan pada penelitian ini dimana menggunakan Rancangan Acak Lengkap (RAL) dengan 5 perlakuan dan 3 ulangan. Perlakuan yang diujikan berbasis pada jumlah berat yang sama antara C. calcitrans dan I. galbana dengan perbandingan berat masing–masing 50%:50%. Perlakuan tersebut adalah A (304.737:137.741 sel/mL), B (373.607:168.871 sel/mL), C (442.478:200.000 sel/mL), D (511.349:231.129 sel/mL) dan E (580.219:262.259 sel/mL). Copepoda Oithona sp. dipelihara dalam botol gelas ukuran 50 mL yang diisi air laut 10 mL dengan kepadatan 1 ind. Oithona sp. per mL. Oithona sp. dipelihara selama 21 hari dengan kondisi suhu 26,67˚C; salinitas 25,67‰; dan pH 9. Hasil penelitian menunjukkan dosis fitoplankton yang berbeda berpengaruh nyata (P<0,05) terhadap Ingestion Rate (Ir) dan peforma pertumbuhan Oithona sp. Berdasarkan hasil penelitian disimpulkan bahwa dosis fitoplankton, C. calcitrans dan I. galbana (50%:50%) sebanyak 511.349:231.129 sel/ml dapat meningkatkan peforma pertumbuhan Oithona sp. yaitu kepadatan total (11,83 ± 0,419 ind./mL), laju pertumbuhan populasi (0,124 ± 0,00215/hari), produksi telur (32,67 ± 2,08 telur/betina) dan memiliki nilai Ingestion Rate (256.597 ± 14.595,729 sel/mL) yang tinggi dibanding perlakuan lain. Kata kunci: Oithona sp., C. calcitrans, I. galbana, Dosis berbeda, Ingestion, pertumbuhan