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At least 19 recordsLinked to original sources
PubMedDate not supplied

Biochemical composition and fatty acid content of zooplankton from tropical lagoon for larval rearing.

Zooplankton samples were collected from the indigenous tropical brackish water lagoon during the wet monsoon (January and February 1990) and the dry monsoon (April and May 1990). The dominant copepod species in the zooplankton community comprising of Oithona sp (especially O. nana and O. robusta) accounted for more than 70% of the zooplankton in January and was gradually replaced by other zooplanktonic species later in the dry season. The lipid contents in zooplankton varied from 0.18 to 1.04% wet weight or 1.14 to 5.92% dry weight respectively. The major fatty acid contents of the zooplankton showed high concentration of 14:0, 16:0, 18:1, 20:5 omega 3 and 22:6 omega 3 especially in the wet season. It also contained high omega-3 highly unsaturated fatty acid series necessary for the growth of commercial fish larvae. It has a better food value than the normally use food organism, brine shrimp; thus reflecting its potential use as food organism for fish larval rearing.

Animal Feed↗
PubMed1995

The growth rate of zooplankton at the edge of chaos: ecological models

This paper tests the hypothesis that systems at the edge of chaos have the highest level of (thermodynamic) information, which supports the hypothesis that systems at the edge of the chaos can coordinate the most complex behavior. This is examined by the use of a realistic ecological lake model describing how an ecological system behaves (i.e. chaotic or ordered), and how the level of information in the system changes when some of the key properties of the focal classes of species are changed. The highest level of information (which is also furthest from thermodynamic equilibrium, as information processes free energy) coincides with realistic properties (parameters) and with a system at the edge of the chaos. The model's key parameter was chosen as the maximum growth rate of zooplankton, as from lake studies, zooplankton growth rate reflects the conditions in the ecosystem and that different zooplankton species have different growth rates. If the key parameter is given a slightly higher value, chaotic behavior emerges. If fish is introduced to the system, the maximum information of the system increases. The maximum zooplankton growth rate giving the highest level of information is reduced if fish are present. This is in accordance with general observations-thus supporting the results. Copyright 1995 Academic Press Limited

Journal Article↗
PubMed1989

Ecology of Vibrio cholerae non-O1 and Salmonella spp. and role of zooplankton in their seasonal distribution in Fukuyama coastal waters, Japan.

Seasonal variation of human pathogens such as Vibrio Cholerae non-01 and Salmonella spp. in Fukuyama coastal waters and the role of zooplankton in their distribution were studies for a period of 1 year. Comparison of two established methods, viz., the elevated temperature method and the two-step enrichment method of enumerating V. cholerae, showed that the former is superior in the recoveries of V. cholerae non-01. Isolation of this pathogen on a wider range of salinities (0.4 to 32.5%) revealed that these organisms are apparently an autochthonous component of the aquatic environment. Temperature appears to be the most crucial element in governing the distribution of V. cholerae non-01. Among the 69 isolates serotyped, 22 different serovars were identified, while one isolate failed to react with any of the known Louisiana State University antisera tested. Zooplankton samples did not harbor more V. Cholerae non-01 than the water column did. Better isolation of an allochthonous pathogen, viz., Salmonella spp., was noticed from the water samples when swabs were employed. Of the 251 isolates serotyped, 18 serotypes with three variants of Salmonella spp. were identified. A high amount of nutrients in the water column increased the survival rate of these pathogens in saline waters as evidenced by a higher incidence of various serotypes in polluted Fukuyama port than in clean marine waters. Salmonella spp. association between V. cholerae non-01 of Salmonella spp. with zooplankton could be noticed as influencing their seasonal distribution.

Animals↗
PubMed1977

Trace metal concentrations and partitioning in zooplankton, neuston, and benthos from the south Texas outer continental shelf.

A variety of marine biota, including zooplankton, sargassum, surface plankton, squid, shrimp, and fish collected along the south Texas Outer Continental Shelf, were analyzed for Cu, Zn, Cd, Pb, Cr, Ni, Fe, and Mn. Although there is a great deal of variation in the chemical content of the various samples, both within species and between species, the variations all fall within the range of values published for similar organisms collected elsewhere. An increase in Pb concentration from north to south, and an increase in Cd concentration from nearshore to further offshore in the zooplankton mirrors the sediment patterns. Statistical analysis of the chemical and biological data for these samples indicates that relatively small percentages of the biological makeup of the sample can markedly affect the concentrations of Pb, Cd, Ni, and Zn. This is particularly true for the larvacea, ostracoda, and mollusca. Chemical analyses of the exoskeletons of shrimp and the skin of both squid and fish indicate that they generally contain higher metal levels in comparison with the flesh from the same organism. This is probably the result of either adsorption from seawater and/or an internal detoxification procedure employed by the organism. The analysis of a composite sample of squid 'pens' indicates that they contain enriched Cu, Cd, Zn, Pb, and Fe levels in comparison with the skin and flesh. These elevated levels are probably the result of an internal detoxification procedure and/or may represent a means of storing necessary metabolites, at least in the case of Cu and Zn, but can not be attributed to adsorption as the chitinous 'pen' is imbedded in tissue and is not directly exposed to seawater.

Animals↗
PubMed1999

Differences in the sterol composition of dominant Antarctic zooplankton.

The composition of free sterols was determined in Antarctic zooplankton species with various feeding behaviors. In the Southern Ocean, the dominant calanoid copepods Calanoides acutus, Calanus propinquus, Metridia gerlachei, and Euchaeta antarctica were investigated during different seasons and compared with the euphausiids Euphausia superba, E. crystallorophias, and Thysanoessa macrura. In addition, the Arctic copepods Calanus hyperboreus, C. glacialis, and C. finmarchicus were studied for comparison. Analyses were performed using gas chromatography and mass spectrometry. The zooplankton species exhibited a simple sterol content of up to six sterols. In the copepods, cholest-5-en-3beta-ol (22.1 to 60.5%, range of sample means), cholesta-5,24-dien-3beta-ol (22.3 to 45.2%), and cholesta-5,22E-dien-3beta-ol (4.3 to 33.4%) contributed most, while in euphausiids the sterol composition was less complex with cholest-5-en-3beta-ol always accounting for more than 75% of the total. Although sterols are membrane constituents and are expected not to vary considerably, differences in the abundance of sterols were observed between the species and the seasons. In herbivorous copepods, cholesta-5,24-dien-3beta-ol increased by a factor of 1.5 to about 45% during the main feeding period in summer; this sterol is a metabolic precursor of cholest-5-en-3beta-ol in the process of the dealkylation of dietary C-24 alkylated phytosterols. Cholest-5-en-3beta-ol decreased by the same proportion. Omnivorous and carnivorous copepods showed average levels of cholesta-5,24-dien-3beta-ol below 25%. These changes in sterol composition between copepod species seem to reflect their different feeding modes.

Animals↗
PubMed1997

Trace metals in field samples of zooplankton from the Fram Strait and the Greenland Sea.

Trace metals (Cd, Pb, Ni, Cu, Zn and Hg) were evaluated in 14 zooplankton taxa collected on cruise ARK IX/Ib of RV 'Polarstern' to the Fram Strait and the Greenland Sea in March and April 1993. We found a substantial interspecific heterogeneity, e.g. with rather low Cd concentrations in calanoid copepods (0.1-0.7 mg kg-1, dry wt.) but remarkably high levels in the decapod Hymenodora glacialis (7-9 mg kg-1) and in the amphipods Themisto abyssorum and T. libellula (24-34 kg-1). In general, Pb was low (< 1 mg kg-1), while some enhanced Ni concentrations were found in the ostracod Conchoecia borealis (66-86 mg kg-1). A comparison to world-wide reported data on marine crustaceans did not reveal any suggestions on increased metal availabilities in both areas investigated, although one might expect a transport of some metals from Siberian rivers across the pole by the Transpolar Ice Drift Stream. However, more information on accumulation strategies of zooplankton under winter and summer conditions is necessary before a full assessment of metals in Arctic waters will be possible.

Analysis of Variance↗
PubMed1997

Solar UVB-induced DNA damage and photoenzymatic DNA repair in antarctic zooplankton.

The detrimental effects of elevated intensities of mid-UV radiation (UVB), a result of stratospheric ozone depletion during the austral spring, on the primary producers of the Antarctic marine ecosystem have been well documented. Here we report that natural populations of Antarctic zooplankton also sustain significant DNA damage [measured as cyclobutane pyrimidine dimers (CPDs)] during periods of increased UVB flux. This is the first direct evidence that increased solar UVB may result in damage to marine organisms other than primary producers in Antarctica. The extent of DNA damage in pelagic icefish eggs correlated with daily incident UVB irradiance, reflecting the difference between acquisition and repair of CPDs. Patterns of DNA damage in fish larvae did not correlate with daily UVB flux, possibly due to different depth distributions and/or different capacities for DNA repair. Clearance of CPDs by Antarctic fish and krill was mediated primarily by the photoenzymatic repair system. Although repair rates were large for all species evaluated, they were apparently inadequate to prevent the transient accumulation of substantial CPD burdens. The capacity for DNA repair in Antarctic organisms was highest in those species whose early life history stages occupy the water column during periods of ozone depletion (austral spring) and lowest in fish species whose eggs and larvae are abundant during winter. Although the potential reduction in fitness of Antarctic zooplankton resulting from DNA damage is unknown, we suggest that increased solar UV may reduce recruitment and adversely affect trophic transfer of productivity by affecting heterotrophic species as well as primary producers.

Animals↗
PubMed1998

Differences between sound scattering by weakly scattering spheres and finite-length cylinders with applications to sound scattering by zooplankton.

A modeling study was conducted to determine the conditions under which fluidlike zooplankton of the same volume but different shapes (spherical/cylindrical) have similar or dramatically different scattering properties. Models of sound scattering by weakly scattering spheres and cylinders of finite length used in this analysis were either taken from other papers or derived and herein adapted for direct comparison over a range of conditions. The models were examined in the very low- (ka << 1, kL << 1), moderately low- (ka << 1, kL > or = 1), and high-frequency regions (ka >> 1, kL >> 1), where k is the acoustic wave number, a is the radius (spherical or cylindrical) of the body, and L is the length of the cylinders (for an elongated body with L/a = 10, "moderately low" corresponds to the range 0.1 < or = ka < or = 0.5). Straight and bent cylinder models were evaluated for broadside incidence, end-on incidence, and averages over various distributions of angle of orientation. The results show that for very low frequencies and for certain distributions of orientation angles at high frequencies, the averaged scattering by cylinders will be similar, if not identical, to the scattering by spheres of the same volume. Other orientation distributions of the cylinders at high frequencies produce markedly different results. Furthermore, over a wide range of orientation distributions the scattering by spheres is dramatically different from that of the cylinders in the moderately low-frequency region and in the Rayleigh/geometric transition region: (1) the Rayleigh to geometric scattering turning point occurs at different points for the two cases when the bodies are constrained to have the same volume and (2) the functional dependence of the scattering levels upon the volume of the bodies in the moderately low-frequency region is quite often different between the spheres and cylinders because of the fact that the scattering by the cylinders is still directional in this region. The study demonstrates that there are indeed conditions under which different shaped zooplankton of the same volume will yield similar (ensemble average) scattering levels, but generally the shape and orientation distribution of the elongated bodies must be taken into account for accurate predictions.

Acoustics↗
PubMed1999

Ordination of zooplankton community data to detect pesticide effects in pond enclosures

Trends in community structure of crustacean zooplankton among 17 forest pond enclosures (5 m x 5 m x 1 m deep) were examined and analyzed to determine effects of two candidate forest pesticides. Eight enclosures were treated at two concentrations of an experimental insecticide, tebufenozide; five were treated at two concentrations of a biological herbicide, bialaphos; and four served as controls. Zooplankton community structure was characterized by ordination of species assemblages using principle components analysis (PCA) and correspondence analysis (CA). Two-dimensional plots of the first two axes from PCA and CA were constructed to explore temporal and treatment-related patterns in community structure. The first four axes of both ordination functions were used as multivariate descriptors of community structure and were examined for differences among treatments by ANOVA. Species ordination plots and sorted rotated factor loadings provided objective means of identifying the species important in determining divergence in community structure. These were considered indicator species and were examined for differences among treatments by ANOVA and specified contrasts. The ordination and subsequent analysis revealed trends in community structure and sample differences that indicated clear, concentration-dependent effects of bialaphos and equivocal effects of tebufenozide.

Journal Article↗
PubMed1979

An electron microscopic study of lipid absorption in the pyloric caeca of rainbow trout (Salmo gairdnerii) fed wax ester--rich zooplankton.

Rainbow trout were killed 4 and 18 h after being fed wax ester-rich marine zooplankton and the absorptive epithelium of the pyloric caeca examined by electron microscopy. Numerous osmiophilic drops were seen in the lamina propria underlying the epithelium of fish killed at both times, but these drops were only abundant within columnar epithelial cells of fish killed 4 h after feeding. Pinocytotic profiles were not common at the luminal plasma membranes, nor were osmiophilic droplets seen in the terminal web area between the luminal plasma membrane and the extensive smooth endoplasmic reticulum. Numerous osmiophilic droplets, 30--100 nm in diameter, were present in the cisternae of the smooth endoplasmic reticulum with up to five separate droplets per individual cisterna. Columnar epithelial cells also contained up to 100 large osmiophilic drops ("conglomerates") which tended to be concentrated in the supranuclear (Golgi) regions. The conglomerates were 250--1200 nm in diameter and were themselves made up of smaller droplets 30--400 nm in diameter. Conglomerates were present both within intracellular membranes and free in the cytoplasm. Osmiophilic droplets in the intercellular spaces and lamina propria were similar in size to individual droplets within conglomerates. We conclude that triacylglycerols are elaborated in the smooth endoplasmic reticulum, transferred to and processed in the Golgi region and finally discharged serosally as chylomicron-like particles of not greater than 400 nm diameter.

Animals↗
PubMed1997

[Growth and carcass quality of carp (Cyprinus carpio L.) fed different cereals, lupin seed or zooplankton].

120 carp (Cyprinus carpio L.) with an average initial weight of 516 g, were kept in 20 tanks at a water temperature of 23 degrees C and given five different commercially practical diets to an end weight of approximately 1000 g. Four of the diets consisted of more than 50% of the traditional sole feeds wheat (W), rye (R), maize (M), or lupin seed (L), mixed with other ingredients to give diets with similar concentration of energy and crude protein. The fifth diet consisted exclusively of deep frozen zooplankton (Z). The fish were given a daily feed amount of 1.8% of bodyweight. The bodyweights of the carp on the cereal diets or the lupin seed diet were similar at the end of the experiment, after 105 days, (W) 995 g, (R) 916 g, (M) 979 g, (L) 979 g, but were significantly lower on diet (Z) at 659 g. Average OM digestibility coefficients for the diets were 77-79% for the cereal-rich diets, 68% for (L), and 75% for (Z). The contents of skinless fillet (average 38.7%), viscera (average 13.2%) and residual carcass (average 48.2%) were similar for the diets with cereals or lupin seed, while fish on diet (Z) had significantly lower fillet proportion (33.6%), coupled with an increase in residual carcass (53.0%). The chemical composition of the fillet, viscera and the residual carcass was also affected. Fish on diet (M) had the highest fat content in the whole body (14.5% of the FM), followed by those on diets (W) and (R) at 13.3% and 12.9%, while fish on diets (L) and (Z) had significantly lower fat contents at 10.7% and 8.2%. Protein contents in the whole body (% of FM) were for diets (L) 16.7%, (W) 16.4% (R) 16.3%, (M) 16.2%, and (Z) 15.5%.

Animals↗
PubMed1983

Preliminary observations on californium-252 behaviour in sea water, sediments and zooplankton.

We carried out radiotracer experiments on the behaviour of 252Cf in the marine environment. The particulate fraction of californium in sea water approached 45% after four days. Californium rapidly adsorbed onto marine coastal and deep-sea sediments with Kd values from 1.4 X 10(4) to greater than or equal to 1 X 10(5). The concentration of 252Cf in euphausiids reached near-equilibrium factors of 3 X 10(2) in water after one week; in contrast, the assimilation from food was very low. Excreted fecal pellets, molts and zooplankton carcasses are potentially important vectors for californium re-distribution in the oceans.

Animals↗
PubMed1998

Sound scattering by several zooplankton groups. II. Scattering models.

Mathematical scattering models are derived and compared with data from zooplankton from several gross anatomical groups--fluidlike, elastic shelled, and gas bearing. The models are based upon the acoustically inferred boundary conditions determined from laboratory backscattering data presented in part I of this series [Stanton et al., J. Acoust. Soc. Am. 103, 225-235 (1998)]. The models use a combination of ray theory, modal-series solution, and distorted wave Born approximation (DWBA). The formulations, which are inherently approximate, are designed to include only the dominant scattering mechanisms as determined from the experiments. The models for the fluidlike animals (euphausiids in this case) ranged from the simplest case involving two rays, which could qualitatively describe the structure of target strength versus frequency for single pings, to the most complex case involving a rough inhomogeneous asymmetrically tapered bent cylinder using the DWBA-based formulation which could predict echo levels over all angles of incidence (including the difficult region of end-on incidence). The model for the elastic shelled body (gastropods in this case) involved development of an analytical model which takes into account irregularities and discontinuities of the shell. The model for gas-bearing animals (siphonophores) is a hybrid model which is composed of the summation of the exact solution to the gas sphere and the approximate DWBA-based formulation for arbitrarily shaped fluidlike bodies. There is also a simplified ray-based model for the siphonophore. The models are applied to data involving single pings, ping-to-ping variability, and echoes averaged over many pings. There is reasonable qualitative agreement between the predictions and single ping data, and reasonable quantitative agreement between the predictions and variability and averages of echo data.

Acoustics↗
PubMed1998

Sound scattering by several zooplankton groups. I. Experimental determination of dominant scattering mechanisms.

The acoustic scattering properties of live individual zooplankton from several gross anatomical groups have been investigated. The groups involve (1) euphausiids (Meganyctiphanes norvegica) whose bodies behave acoustically as a fluid material, (2) gastropods (Limacina retroversa) whose bodies include a hard elastic shell, and (3) siphonophores (Agalma okeni or elegans and Nanomia cara) whose bodies contain a gas inclusion (pneumatophore). The animals were collected from ocean waters off New England (Slope Water, Georges Bank, and the Gulf of Maine). The scattering properties were measured over parts or all of the frequency range 50 kHz to 1 MHz in a laboratory-style pulse-echo setup in a large tank at sea using live fresh specimens. Individual echoes as well as averages and ping-to-ping fluctuations of repeated echoes were studied. The material type of each group is shown to strongly affect both the overall echo level and pattern of the target strength versus frequency plots. In this first article of a two-part series, the dominant scattering mechanisms of the three animal types are determined principally by examining the structure of both the frequency spectra of individual broadband echoes and the compressed pulse (time series) output. Other information is also used involving the effect on overall levels due to (1) animal orientation and (2) tissue in animals having a gas inclusion (siphonophores). The results of this first paper show that (1) the euphausiids behave as weakly scattering fluid bodies and there are major contributions from at least two parts of the body to the echo (the number of contributions depends upon angle of orientation and shape), (2) the gastropods produce echoes from the front interface and possibly from a slow-traveling circumferential (Lamb) wave, and (3) the gas inclusion of the siphonophore dominates the echoes, but the tissue plays a role in the scattering and is especially important when analyzing echoes from individual animals on a ping-by-ping basis. The results of this paper serve as the basis for the development of acoustic scattering models in the companion paper [Stanton et al., J. Acoust. Soc. Am. 103, 236-253 (1998)].

Acoustics↗
PubMed1976

Phosphatases in lake water: characterization of enzymes from phytoplankton and zooplankton by gel filtration.

Sephadex gel filtration was used to characterize phosphomonoesterases in two small takes in northern Sweden. Two fractions, here termed phosphatase A and phosphatase B, were found both as free enzymes and associated with seston. The activity of phosphatase A was correlated with the presence of algal biomass. Phosphatase B, on the other hand, was derived from zooplankton. Phosphate served as an effective inhibitor of phosphatase A but had no such effect on phosphatase B. Both fractions had pH optima between 6.5 and 7.0.

Chlorophyta↗
PubMed1990

Attachment of Vibrio cholerae serogroup O1 to zooplankton and phytoplankton of Bangladesh waters.

Vibrio cholerae serogroup O1, the causative agent of cholera, is capable of surviving in aquatic environments for extended periods and is considered an autochthonous species in estuarine and brackish waters. These environments contain numerous elements that may affect its ecology. The studies reported here examined physical interactions between V. cholerae O1 and natural plankton populations of a geographical region in Bangladesh where cholera is an endemic disease. Results showed that four of five clinical V. cholerae O1 strains and endogenous bacterial flora were attached preferentially to zooplankton molts (exuviae) rather than to whole specimens. One strain attached in approximately equal numbers to both exuviae and whole specimens. V. cholerae O1 also attached to several phytoplankton species. The results show that V. cholerae O1 can bind to diverse plankton species collected from an area where cholera is an endemic disease, with potentially significant effects on its ecology.

Animals↗
PubMed1987

A method for cytogenetic and cytological examination of small shelled larvae of bivalves and other zooplankton.

Studies on chromosomes and nuclei of very small bivalve larvae have been impeded by the veliger shell. It has been determined that the alcohol:acetic acid fixative commonly used in cytogenetic techniques can be made to act as a decalcifying agent upon repeated heating. In addition, transfer of formalin fixed shelled specimens, routinely used as marine bioassay organisms, into ethyl alcohol:acetic acid (3:1) fixative also yields clear cells for cytological examination of decalcified but otherwise intact oyster larvae and other zooplankton. Identification of cell type, such as germ-line primordia, in, for example, reproductive and ploidy level studies, and observations on the presence of bacteria can be made from the preparations. Material can be examined up to at least a year after preservation. The method is evaluated and its modifications are discussed.

Acetates↗
PubMedDate not supplied

Reaction of freshwater phyto- and zooplankton to pesticides.

The reaction of plankton to the toxic effect of pesticides is considered at four levels: the cell, the organism, the population, and the biocenosis. The basis for the methodological approach to evaluation of response at the cell level was the principle of phase reactions. Depending on concentration, the pesticides may either suppress or stimulate the plankton organisms. Temperature may be decisive intoxic effects (pesticides are effective in a range of 15 to 25 degrees C). Most pesticides having algacidal activity are effective in a range of concentrations of 1-10 mg/liter. Phytoplankton as a whole has a high buffer capacity with respect to pesticides. Changes in ratios of basic components of phytoplankton effected by pesticides most often lead to a change of the dominant. Analogical changes are characteristic also for zooplankton; pesticides lead to the elimination of water fleas from its composition. The stimulating effect of a low concentration of pesticides, changes in the functional activity of the components of bacterial plankton, and changes coupled with this in biogeochemical cycles of nitrogen and phosphorous as well as elimination of water fleas from the plankton promotes the development of "secondary" eutrophication, that is, an increase in the biomass of the phytoplankton.

Animals↗