Journal of Plankton Research - Advance Access

Taxonomy of Oncaeidae (Copepoda, Cyclopoida s.l.) from the Red Sea. IX. Epicalymma bulbosa sp. nov., first record of the genus in the Red Sea

Bottger-Schnack, R. — 2009-07-02

The oncaeid genus Epicalymma comprises small copepod species usually living at meso- and bathypelagic depth layers in oceanic areas. The genus had previously been assumed to be absent from the Red Sea, due to the unusually high deep-sea temperatures and salinities in this area. In the present account a new species, Epicalymma bulbosa, is described from the Red Sea, which appears to be the only representative of the genus in the region. The new species is the smallest Epicalymma species so far recorded, with a total body length of ~0.32 and ~0.29 mm in the female and male, respectively. Apart from its small size, it differs from all known Epicalymma species by an extremely long exopodal seta on P5 in both sexes, and by a free exopod segment of P5 and a very long and basally swollen spinule on the syncoxa of the maxilliped in the female. In contrast to other Epicalymma species, which are distributed between 500 and >2500 m depth, the new species occurred much shallower (100–750 m) in the Red Sea, which may be interpretated as an avoidance mechanism of the unfavourable environmental conditions in the deep Red Sea. The taxonomic status of the new species within the genus Epicalymma is discussed and the few available ecological data on Epicalymma species in the world ocean are summarized.

Photosynthetic features and primary productivity of phytoplankton in the Oyashio and Kuroshio-Oyashio transition regions of the northwest Pacific

2009-06-28

Diel and seasonal changes in the photosynthetic physiology of phytoplankton and primary productivity were investigated during 2005, together with community composition in the Oyashio (OY) and Kuroshio–Oyashio transition (TR) regions of the northwest Pacific. In both regions, diel changes in the maximum photosynthetic rate (P*_max) and the light saturation index (E_k) in the photosynthesis–irradiance (P–E) curve were observed, due to diel differences in photo-physiology. In the OY region, the highest values of chlorophyll a concentration, depth-integrated primary production and the maximum quantum yield of carbon fixation in photosynthesis (_{c max}) were observed in May when diatom blooms occurred. Furthermore, a higher water-column light utilization efficiency () of photosynthesis for phytoplankton was found in the OY region in both May and September. In contrast, in the TR and warm-core ring regions, _{c max} was nearly constant, while depth-integrated primary production in May was significantly lower than in the OY region. These results show that the spring phytoplankton assemblages in OY waters had a higher light utilization ability during photosynthesis. Such a high photosynthetic property would contribute to the highest seasonal biological drawdown of surface pCO₂ among the world's oceans (Takahashi, T., Sutherland, S. C., Sweeney, C. et al. (2002) Global sea–air CO₂ flux based on climatological surface ocean pCO₂, and seasonal biological and temperature effects. Deep-Sea Res. II, 49, 1601–1622).

Building the "perfect beast": modelling mixotrophic plankton

Flynn, K. J., Mitra, A. — 2009-06-28

A mechanistic model is described for carbon–nitrogen–phosphorous-based interactions within a protistan mixotroph. The model describes interactions between photosynthesis (with photoacclimation), inorganic nutrient acquisition and the consumption of prey, making use of a flexible structure to allow an exploration of alternative modes of interaction. Operation can be varied with respect to differential growth rates under pure phototrophy, phago-heterotrophy or mixotrophy, substitutional or additive interactions between modes of C acquisition, the suppression of digestion by C flow from photosynthesis (including, if applicable, that from kleptochloroplasts), competition for volume within the cell between chloroplasts and food vacuole, the need for some level of obligatory photosynthetic activity, activation of mixotrophy in response to general growth limitation, or to specific nutrient limitations. Simulations under dynamic conditions include considerations of predation on bacteria, and on microalgae. These show the potential for mixotrophs, but also indicate the importance of using an appropriate description of their physiology, with different mixotrophy configurations having significant effects on system dynamics. The potential value of kleptochloroplasts for support of mixotroph growth is highest when the food vacuole is large, when the ingested phototroph prey is of good nutritional status and when digestion of prey is repressed by photosynthesis. Analyses of the behaviour of the new model demonstrate that simulations which do not consider the stoichiometric implications of mixotrophy cannot reflect the reality of the trophic interaction both for the mixotroph and for the associated ecosystem.

We dedicate this work to the memory of Mike Fasham FRS, without whose enthusiasm and guidance none of this would have come to pass.

Acrocalanus gracilis (Copepoda: Calanoida) development and production in the Timor Sea

Gusmao, L. F. M., McKinnon, A. D. — 2009-06-26

We investigated the juvenile development of the calanoid copepod Acrocalanus gracilis in the Timor Sea. The development was characterized by the calculation of stage-specific duration, median development time, moulting period duration, moult and growth rates. The morphometry of the experimental and wild populations were compared. Food concentrations in the experiment were lower than those in the field, and resulted in smaller animals than those in the field. Somatic growth (0.44 day^–1) was log-linear throughout the development, but moulting rates slowed with time. The development of A. gracilis was similar to other paracalanids, and conforms to the equiproportional model. Trophic resources seem to play an important role in controlling the developmental features and morphometry of Acrocalanus in tropical environments.

Cyanobacteria and microcystin-LR in a complex lake system representing a range in trophic status: Lake of the Woods, Ontario, Canada

Chen, H., Burke, J. M., Mosindy, T., Fedorak, P. M., Prepas, E. E. — 2009-06-21

Euphotic water samples were collected monthly from 16 sites in Lake of the Woods, Ontario, Canada from July to September, 2006 and 2007. Sites represented a range of inorganic nitrogen and phosphorus concentrations and mixing regimes, which was reflected in the spatial variability in phytoplankton biomass and community composition, and cyanobacterial toxin [microcystin-LR (MC-LR)] concentrations. Nutrient concentrations decreased along a south to north transect, concomitant with distance from the main river inlet at the south end of the lake. Filamentous, nitrogen-fixing Aphanizomenon spp. and Anabaena spp. were dominant at most sites: Aphanizomenon was more abundant at southern sites and Anabaena was more abundant at northern sites. MC-LR was detected at all sites at least once (maximum concentration 0.69 µg L^–1). However, there was no correlation between MC-LR concentration and the biomass of Anabaena, a documented MC-LR producer. For the pooled data set, total phosphorus and ammonium concentrations were the two parameters most strongly related with MC-LR concentration. Principal components analysis was used to analyze the data set; it indicated that two factors accounted for 81% of the variability among the 12 environmental parameters tested. Factor 1 represented physicochemical characteristics and phytoplankton biomass and Factor 2 represented Anabaena and Woronichinia biomass.

Parameterizing plankton functional type models: insights from a dynamical systems perspective

Cropp, R., Norbury, J. — 2009-06-21

The spectre of anthropogenic global climate change has focused attention on biogeochemical cycling in the oceans as marine plankton ecosystems are involved in the cycling of several compounds thought to have significant implications for climate. To better understand these processes, modellers are developing plankton functional type (PFT) models that group plankton according to their biogeochemical properties. There is some debate as to whether our understanding of plankton ecosystems is sufficiently well developed for PFT models to be reliable and for their predictions to be treated with confidence. In this paper, we examine the dynamical properties of a generic predator–prey–prey PFT model, then apply these analysis techniques to a simple example PFT model with two phytoplankton and one zooplankton in order to explore its parameter space. We find that parameter combinations for which all PFTs stay extant for all time appear rare, but develop a simple heuristic that allows such parameter sets to be identified relatively easily for many PFT models. We observe that such systems often have phytoplankton with similar growth rates, but that differ in other properties such as differing nutrient utilization strategies or different susceptibilities to grazing. We also note that persistent PFT systems are more likely if neither phytoplankton have a low specific mortality rate or is a highly nutritious food for the grazer.

Photoheterotrophy in marine prokaryotes

Zubkov, M. V. — 2009-06-18

Despite considerable advances in the understanding of the various microbial photoheterotrophic mechanisms, the role of solar radiation in the metabolism of bacterioplankton in the ocean is difficult to assess. It is already apparent that rates of CO₂ fixation by prokaryotic cells may be only a part of the picture. Photophosphorylation is difficult to differentiate from respiratory phosphorylation and other types of ATP synthesis. Solar energy could by-pass ATP synthesis, instead being used to generate a proton-motive force, which in turn could be directly used for cell motility or even for importing molecules into cells. In addition, photoheterotrophic prokaryotes could actively regulate intake and use of solar energy for different metabolic functions depending on the energetic demands of the cell. The factors listed above hence require consideration when solar energy input into metabolism of oceanic photoheterotrophic prokaryotes is experimentally quantified and numerically modelled.

Testing the relationship between primary production and Acartia tonsa grazing pressure in an estuarine lagoon

Calliari, D., Britos, A., Conde, D. — 2009-06-17

Flow of carbon to large consumers in marine environments is mediated by copepods. Globally, copepod grazing removes a small fraction of pelagic primary production, and that fraction decreases from oligotrophic to productive ecosystems. Such a pattern should result from mechanisms whose validity has not been explicitly tested. We analysed the relationship between primary production and copepod herbivory pressure (HP) in a subtropical lagoon under the hypothesis that HP is higher during periods of low, compared to periods of high productivity. On 18 occasions during 2 years, we estimated primary production as ¹⁴C incorporation, and herbivorous grazing (as gut fluorescence) and egg production rates for the dominant zooplankter Acartia tonsa. Primary production varied between 18 and 407 mg C m^–2 day^–1; A. tonsa HP was low (max. of ca. 5% or 18%, depending on assumptions) and followed a non-linear negative pattern with primary production consistent with expectations. The herbivorous fraction of A. tonsa diet was usually <50%, suggesting strong trophic links with microbial processes. Despite sustained high fecundity (11–83 eggs female^–1 day^–1), population density of A. tonsa was moderate or low, which contributed to low HP. Top-down control on copepods, also suggested by earlier studies in this ecosystem, may be one factor constraining fluxes via the herbivory pathway.

Dinoflagellate cyst production on the southern Namaqua shelf of the Benguela upwelling system

Pitcher, G. C., Joyce, L. B. — 2009-06-10

To study dinoflagellate cyst production in the southern Benguela, a sediment trap was deployed for a period of 3.5 years at a single station located downstream of the Cape Columbine upwelling cell on the southern Namaqua shelf. The cyst assemblage of surface sediments below the trap was also investigated. Twenty-nine different cyst types were recorded of which 25 were from the sediment trap, and 22 from the surface sediments. The flux of cysts followed a clear seasonal trend with an initial peak in spring followed by a major peak in autumn; with a mean flux for the entire period of deployment of 1.4 x 10⁶ cysts m^–2 day^–1. Of the cysts recovered from the trap, those of heterotrophic dinoflagellates were six times more abundant than those of autotrophic dinoflagellates. The study also revealed the presence of cysts of species previously unrecorded in the plankton of the southern Benguela, specifically the toxic dinoflagellate Lingulodinium polyedrum.

Viral persistence in water as evaluated from a tropical/temperate cross-incubation

Bettarel, Y., Bouvier, T., Bouvy, M. — 2009-06-09

Virucidal properties of sunlight and temperature have been identified for a long time. However, it is less well established if virioplankton communities are evenly susceptible or geographically adapted to these environmental factors. Transplant experiments were conducted between a tropical (Senegal) and temperate (France) site to examine the effect of natural daylight conditions and temperature on the persistence of free viruses in water. Fresh- and seawater viruses from both countries were simultaneously subjected to 12 h of full sunlight and dark exposure under their native and "transplanted" latitudes. Consistently, viruses decayed much faster when incubated abroad, regardless of origin (latitude and/or water type). However, viral losses, in most cases, were not significantly different between sunlight exposed and dark samples, implying that ambient radiation does not exert strong negative effects on virioplankton particles. Rather, temperature clearly emerged as the principal determinant of viral survival in all samples. This suggests that viruses, under local temperature, can adapt through an evolutionary process to survive for longer periods of time thus increasing their chances to encounter their hosts.

Estuarine and oceanic influences on copepod abundance and production of a subtropical coastal area

Miyashita, L. K., Melo Junior, M. d., Lopes, R. M. — 2009-06-09

We investigated the influence of nutrient-rich oceanic waters in comparison to the estuarine outflow from Santos Bay (SE Brazil) on copepod abundance and production on the adjacent inner shelf. Zooplankton samples were collected with a Multinet in spring 2005 and in summer 2006. Copepod biomass was derived from length–weight regressions, and growth rates were estimated from empirical models. Altogether, 58 copepod taxa were identified. The highest abundances were due to small-sized organisms including nauplii, oncaeids and copepodids of paracalanids and clausocalanids. Biomass and secondary production mirrored copepod abundance, with Temora copepodids accompanying the above-mentioned taxa as major contributors. The contribution of naupliar biomass and production was low (2.2 and 3.8% of the total, respectively). The influence of the Santos Bay outflow was observed only in spring, when Coastal Water (CW) dominated at the study site; whereas in summer the inner shelf was occupied by CW in the surface layer and the oceanic South Atlantic Central Water (SACW) in the bottom layer. The SACW intrusion had more of an influence for the increase in copepod production than the Santos Bay plume. The distribution and dynamics of the oceanic water masses seemed to be the most important influence on copepod diversity and production at this subtropical site.

Air-dispersed phytoplankton in a Mediterranean River-Reservoir System (Aliakmon-Polyphytos, Greece)

Chrisostomou, A., Moustaka-Gouni, M., Sgardelis, S., Lanaras, T. — 2009-06-03

The air-dispersed phytoplankton diversity and colonization potential, in a Mediterranean River-Reservoir System (Aliakmon-Polyphytos, Northern Greece), were studied. Phytoplankton samples were collected weekly, from five sampling sites in the river-reservoir system (for 11 weeks) and from jars replaced weekly for 10 successive weeks placed at one colonization site (CS) (for 10 weeks). The algal diversity in the river-reservoir system was high. The air-dispersed algae in the CS jars included taxa of the local species pool (reservoir phytoplankton), including taxa of the airborne algae common in most biogeographic regions. Both small- and large-sized phytoplankton in the vegetative form of unicells, small coenobia, large colonies and filaments were observed in the CS jars. Nanoplanktic algae and among them the known allergenic chlorophyte Chlorella were the most frequent and abundant air-dispersed algae. The large-sized chlorophytes Mougeotia sp. and Ulothrix sp. were also frequently air-dispersed in the CS jars. Chlorophytes exhibited the highest colonization potential, followed by diatoms and cyanobacteria. Evidence is provided that over short distances, the wind is an important agent for the dispersal of phytoplankton with different colonization potentials, including the bloom-forming toxic cyanobacterium Microcystis aeruginosa.

Inter-specific scaling of phytoplankton production and cell size in the field

Maranon, E. — 2009-06-02

Effects of intra- and inter-annual variability in prey field on the feeding selectivity of larval Atlantic mackerel (Scomber scombrus)

Robert, D., Castonguay, M., Fortier, L. — 2009-06-02

Response of heterotrophic bacteria, autotrophic picoplankton and heterotrophic nanoflagellates to re-oligotrophication

Kamjunke, N., Straile, D., Gaedke, U. — 2009-06-02

We investigated the response of the microbial components of the pelagic food web to re-oligotrophication of large, deep Lake Constance where total phosphorus concentrations during mixing decreased from a maximum of 2.81 µmol L^–1 in 1979 via 1.87 µmol L^–1 in 1987 to 0.26 µmol L^–1 in 2007. Measurements of heterotrophic bacteria, autotrophic picoplankton (APP) and heterotrophic nanoflagellates (HNF) in 2006 and 2007 were compared to values from 1987 to 1997. We hypothesized that the biomass and seasonal variability of all groups will decrease under more oligotrophic conditions due to reduced resource availability, particularly for APP and HNF but less for the competitively stronger bacteria. Average bacterial biomass between spring and autumn was unrelated to phosphorus, whereas the ratio of bacterial biomass to chlorophyll a concentration increased with decreasing trophy due to declining chlorophyll concentrations. In contrast, a unimodal relationship was found between APP and phosphorus with low biomass at low and high phosphorus concentrations and maximum biomass in between. Average HNF biomass decreased strongly by a factor of 10–30 with decreasing trophy, and chlorophyll-specific HNF biomass was unimodally related to phosphorus. The relative seasonal biomass variability did not change for any group during re-oligotrophication. To conclude, HNF responded much more strongly and bacteria less so than chlorophyll concentrations to oligotrophication, whereas APP exhibited a more complex pattern.

In situ behaviour and acoustic properties of the deep living jellyfish Periphylla periphylla

Klevjer, T. A., Kaartvedt, S., Bamstedt, U. — 2009-05-25

The importance of jellyfish in marine systems is increasingly being recognized, and in some ecosystems, jellyfish may now be considered the top predator. We studied the behaviour of individuals of the deep-water schypozoan Periphylla periphylla in one such location, the Lurefjord, Norway. The study was performed using a combination of submersible acoustics (38 kHz), video and net methods, and the focus was on variation in behaviour and vertical distribution in relation to the diel cycle. A proportion of the population underwent synchronous vertical migrations, but P. periphylla were still recorded throughout the water column both day and night. The majority of individuals were swimming (vertically) at speeds <2 cm s^–1 irrespective of the time of day. However, occasional vertical swimming events with speeds exceeding 10 cm s^–1 were recorded. Such events of elevated vertical speeds were of short duration, followed by subsequent periods of no vertical movements. Different size fractions appeared to have different patterns of vertical swimming activity, with smaller jellyfish swimming more continuously than the larger Periphylla. The echo strengths of the individual returns (target strength, TS) peaked at approximately –62 dB, and variability in TS for individuals was high, with the strongest echoes seen in deep water. The results show the feasibility of acoustic methods for studying the in situ behaviour and acoustic properties of these jellyfish, but also that acoustically weak jellyfish are only recorded close to the transducer or the acoustic axis, which will bias acoustic data on vertical size distribution and acoustic abundance estimates.

Preservation of the invasive ctenophore Mnemiopsis leidyi using acidic Lugol's solution

Engell-Sorensen, K., Andersen, P., Holmstrup, M. — 2009-05-25

During baseline studies of ichthyoplankton for environmental impact assessment in the Western Baltic Sea, we developed a simple method for preservation of the abundant ctenophore, Mnemiopsis leidyi, using acidic Lugol's solution.

Abundance trends and ecology of planktonic ciliates of the south-western Atlantic (35-63{degrees}S): a comparison between neritic and oceanic environments

Santoferrara, L., Alder, V. — 2009-05-19

Ciliates from sub-surface waters of the Argentine shelf and the Drake Passage under austral summer and autumn conditions were examined and compared for the first time. In both environments, the taxonomic structure of ciliates was related to temperature and salinity, and aloricate oligotrichs dominated in density (80%) over loricate oligotrichs, litostomatids and prostomatids, while the microplanktonic fraction prevailed in terms of biomass (90%) over the nanociliates. Myrionecta rubra was found all along the Argentine shelf only in autumn, but showed isolated peaks of abundance (10³ ind. L^–1) during summer. Mean values of density and biomass of total ciliates decreased ca. 2-fold from the shelf-slope to oceanic waters, while potential maximum production of aloricate oligotrichs decreased 9-fold, in relation with the drop in chlorophyll a concentration and the latitudinal decline of temperature, also reflected in maximum growth rates. Fifty percent of total ciliate abundance was represented by local increases (maximum: 20 000 ind. L^–1 and 25 µg C L^–1), which were spatially superimposed with ranges of seawater temperature and chlorophyll a concentrations of 10–15°C and 0.6–6 µg L^–1, respectively, and were found in the nearby of fronts located on the shelf and the slope.

Changes in phytoplankton and microzooplankton populations during grazing experiments at a Mediterranean coastal site

Modigh, M., Franze, G. — 2009-05-17

Microzooplankton grazing on phytoplankton populations was investigated by means of eight dilution experiments in different seasons and trophic conditions at station Mare Chiara, a long-term study site in the Gulf of Naples, Tyrrhenian Sea. To check for changes in prey and predator populations, size-fractionated chlorophyll and HPLC analyses and microzooplankton counts were performed before and after the incubations. On average, 68% of daily phytoplankton production was consumed by the microzooplankton in spring and summer, and in winter, more than 100% of phytoplankton daily production was consumed. Nutrients were added in four of our experiments. Diatoms (as recorded by fucoxanthin concentrations) increased significantly in the nutrient-enriched experiments, and unexpectedly, also heterotrophic dinoflagellate growth was enhanced by nutrient additions. Remarkable changes in grazer abundance were observed in several experiments; a substantial difference was found in microzooplankton grazing pressure (g/k x 100) as calculated by regression of apparent chlorophyll a growth against nominal dilution factor or against average predator concentrations, 72 ± 19% and 60 ± 23% of phytoplankton daily production, respectively. However, our observations suggest that if growth and mortality of grazers in the dilution series are not considered, microzooplankton grazing impact may be either underestimated, at low phytoplankton growth rates, or overestimated in more productive conditions.

Preservation of the larval ctenophore Mnemiopsis leidyi A. Agassiz (Ctenophora, Lobata)

Sullivan, L. J., Gifford, D. J. — 2009-05-14

Mnemiopsis leidyi larvae were preserved quantitatively for up to 1 year in 5–20% acid Lugol's solution. The highest preservation efficiency and least shrinkage and deformation occurred in the 5% treatment.

Quantification of the abundance and distribution of the common jellyfish Aurelia aurita s.l. with a Dual-frequency IDentification SONar (DIDSON)

Han, C.-H., Uye, S.-I. — 2009-05-14

A Dual-frequency IDentification SONar (DIDSON) provided a powerful tool to determine the numerical abundance and spatial distribution of medusae of the common jellyfish Aurelia aurita s.l. in shallow coastal waters. The sonar image obtained in high frequency (1.8 MHz) mode enabled us to identify and count individual medusae of 4.1–19.6 cm (mean: 13.1 cm) bell diameter. Deployment of the DIDSON along three ~4-km-long transects in a shallow brackish-water lake (average depth: 5.1 m) revealed that A. aurita aggregated (e.g. >8.0 medusae m^–3) near the lake center. The medusae occurred throughout the water column, but tended to avoid low salinity surface and deoxygenated bottom layers. The overall average density of medusae estimated by the DIDSON was 3.3 times higher than that estimated by net sampling. Use of a DIDSON can facilitate quantitative determination of jellyfish populations that cause problem blooms worldwide in order to better understand their ecological importance.

A Mechanistic Approach to Plankton Ecology

Miller, C. B. — 2009-05-12

Growth and survival responses of a tropical Daphnia (Daphnia lumholtzi) to cell-bound microcystins

Semyalo, R., Rohrlack, T., Larsson, P. — 2009-05-11

Eutrophic tropical freshwater bodies often have cyanobacterial blooms that last throughout the year and some of these blooms may produce compounds that are toxic to Daphnia. Nevertheless, tropical species like Daphnia lumholtzi continue to remain abundant in the presence of such blooms. We conducted an experiment on the growth and survival of D. lumholtzi. We fed a toxic cyanobacteria Microcystis aeruginosa PCC 7806 to study the response of D. lumholtzi to cell-bound microcystins. Daphnia lumholtzi showed poor growth and survival in the presence of M. aeruginosa PCC 7806 both with and without microcystins. Survival and growth improved significantly when M. aeruginosa comprised <50% of the food offered. However, regardless of the amounts of M. aeruginosa in the food, we did not find any significant difference in the growth or survival between the microcystin-containing and the microcystin-lacking treatments. We observed a significant difference in age at maturity between the microcystin-containing and the microcystin-lacking groups when the amount of M. aeruginosa in the food offered was <50%. The toxic cyanobacteria M. aeruginosa PCC 7806 contains substances other than microcystins that reduce the growth and survival of the tropical D. lumholtzi. However, under low cyanobacteria concentrations and in the absence of microcystins, D. lumholtzi shows improved reproduction rates.

Spatiotemporal transition of bacterioplankton diversity in a large shallow hypertrophic freshwater lake, as determined by denaturing gradient gel electrophoresis

Tian, C., Tan, J., Wu, X., Ye, W., Liu, X., Li, D., Yang, H. — 2009-05-04

To describe the variation in bacterioplankton diversity within a large hypertrophic freshwater lake, as well as changes in the diversity that occurred with time, PCR- (denaturing gradient gel electrophoresis) DGGE was utilized to study water samples collected from Lake Taihu in China. To accomplish this, water samples were collected from different locations and during different months. The trophic status of these sampling sites ranged from eutrophic to hypertrophic. Cluster and multidimensional scaling analyses revealed that the temporal transition in the diversity of the bacterioplankton occurred primarily in response to a cyanobacterial bloom, and that all samples could be divided into normal-bloom, peak-bloom and winter period groups. Spatial differences in the bacterial diversity were also detected among the three sampling sites, with diversity being found to be strongly correlated with the gradient of the trophic status of the three sampling sites. In addition, these temporal and spatial changes could be characterized by several specific DGGE bands. The results were further analyzed by canonical correspondence analysis, which revealed that the bacterioplankton diversity of Lake Taihu was primarily associated with temperature, pH, total nitrogen (TN), total phosphorus (TP) and dissolved oxygen. Of these factors, TN and TP were only shown to be significant influencing factors at Wuxi, which had the highest trophic level.

WITHDRAWN: Morphological variation in Alexandrium tamiyavanichii and Alexandrium minutum (Dinophyceae)

Lim, P.-T., Ogata, T. — 2005-05-26

This paper has been withdrawn at the request of the authors.