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1.
A new photodegradable molecule as a low impact ballast water biocide: efficacy screening on marine organisms from different trophic levels 总被引:1,自引:0,他引:1
M. Faimali F. Garaventa E. Chelossi V. Piazza O.D. Saracino F. Rubino G.L. Mariottini L. Pane 《Marine Biology》2006,149(1):7-16
Marine species carried by the ships’ ballast waters are a potentially serious environmental problem. Many strategies are being
adopted to minimize the transfer of invasive or pathogenic marine species between different aquatic ecosystems. This problem
is often addressed by using biocides for ballast water treatment; however, the biocide could be dangerous to native organisms
once the ballast water is discharged. Chemical treatments such as chlorination and addition of glutaraldehyde could cause
problems related to toxicity and application costs. The search for new effective molecules with a low environmental impact
is pressing. This paper presents data from a preliminary efficacy screening of a promising molecule derived from alkylated
naphtoquinones on a battery of ballast water model organisms. Results show that this new molecule is very effective in the
absence of light and is extremely photodegradable (half-life <6 h). It can thus be easily degraded when released in the environment.
Physical and Chemical Impacts on Marine Organisms, a Bilateral Seminar Italy-Japan held in November 2004. 相似文献
2.
Most studies characterizing successful biological invaders emphasize those traits that help a species establish a new population.
Invasions are, however, multi-phase processes with at least two phases, dispersal and introduction, that occur before establishment.
Characteristics that enhance survival at any of these three phases will contribute to invasion success. Here, we synthesize
information on the dispersal, introduction, and establishment of fishes mediated by ship ballast-water transport. We synthesize
54 reports of at least 31 fish species collected from ballast tanks (Phase 1), including 28 new reports from our recent studies
(1986 to 1996). Our literature survey revealed 40 reports of 32 fish species whose introductions have been attributed to ballast
transport (Phase 2), of which at least 24 survived to establish persistent populations (Phase 3). We detected little overlap
at the species level between these two data sets (Phase 1 vs Phases 2 and 3), but patterns emerged at the family level. The
Gobiidae (6 species), Clupeidae (4 species), and Gasterosteidae (1 species) were the most commonly found fish families in
ballast tanks (Phase 1). The Gobiidae (13 species), Blenniidae (6 species) and Pleuronectidae (2 species) dominated the list
of ballast-mediated introductions (Phase 2); gobies and blennies were the families most frequently established (Phase 3).
The invasive success of gobies and blennies may be explained in part by their crevicolous nature: both groups seek refuge
and lay eggs in small holes, and may take advantage of the ballast-intake holes on ship hulls. This behavior, not typically
associated with invasive ability, may contribute to successful introduction and establishment by facilitating the dispersal
phase of invasion. The failure of the pleuronectids to invade may reflect poor salinity match between donor and recipient
regions. To develop a predictive framework of invasion success, organisms must be sampled at all three phases of the invasion
process. Our comparison of two ballast sampling methods suggests that fishes have been undersampled in ballast-water studies,
including our own, and that the role of ballast transport in promoting fish invasions has been underestimated.
Received: 13 January 1999 / Accepted: 24 February 2000 相似文献
3.
Thomas Hofer Hartmut Nies Stephan Gollasch Rolf von Ostrowski 《Environmental Sciences Europe》2007,19(4):219-225
Background and Scope
The marine shipping lanes have become the most important path for the invasion of foreign aquatic organisms. The increasing global trade results in an increase in the number of marine vessels. Without any protective measures, with every ship carrying foreign organisms the risk of biological invasions will rise.Results
The International Martime Organization (IMO) of the United Nations developed a convention to reduce the transfer of organisms with ballast water. After the entry-into-force of this convention the fleet of the world has to be equipped with effective ballast water management technology before 2016. This article discusses potential options for action. To comply with the limit values of the ballast water convention, the current state of the art demands the use of active substances. Any decision on the approval of active substances used for ballast water treatment and the environmental impact assessment lies with the IMO. Proposed to day are UV-radiation, active chlorine, active oxygen, the creation of biocides through electrolysis and a change in gases contained in the ballast water. The technologies and the potential risks are presented.Conclusions
Despite the introduction of an approval procedure by IMO any reliable assessment of the real risks involved in the use of biocides is impossible, as the risk assessment approaches have still to be developed. On the regulatory level, the main focus in data requirements for the risk assessment is on a comprehensive testing of the toxic potential of the biocides proposed. Strategies for the identification and evaluation of the chemical resulting from the treatment of limnic, marine and brackish water are not fully developed. An integrating assessment of risks involved in the introduction of foreign organisms versus the toxic effects of the substances used or created during treatment is still missing. 相似文献4.
Colonization dynamics in trophic-functional structure of periphytic protist communities in coastal waters 总被引:1,自引:0,他引:1
Wei Zhang Henglong Xu Yong Jiang Mingzhuang Zhu Khaled A. S. Al-Rasheid 《Marine Biology》2012,159(4):735-748
The colonization dynamics in trophic-functional patterns of periphytic protist communities was studied in coastal waters of
the Yellow Sea, northern China, from May to June, 2010. The periphytic protists represented different trophic-functional structures
during colonization process. Only certain trophic-functional groups (e.g., photoautotrophs, algivores and non-selectives)
occurred within the protist communities with low species number and abundance at the initial stage (1–3 days), while more
trophic-functional groups (e.g., photoautotrophs, algivores, non-selectives and raptors) contributed to the communities with
increased and peaked species number and abundance at the transitional (7–10 days) and equilibrium (14–28 days) stages, respectively.
All heterotrophic groups were significantly fitted the MacArthur–Wilson model in colonization curves and represented higher
species number and colonization rates at a depth of 1 m than at 3 m. These results may provide necessary understandings for
ecological researches and monitoring programs using periphytic protists with different colonization ages in marine ecosystems. 相似文献
5.
N. Aberle Thomas Hansen Ruth Boettger-Schnack Antje Burmeister Anton F. Post Ulrich Sommer 《Marine Biology》2010,157(1):157-169
Mesozooplankton communities in the meso-oligotrophic Gulf of Aqaba, Northern Red Sea, were investigated over a 2 years period
(2005–2007) with emphasis on the trophodynamic relations among different taxonomic groups ranging from primary consumers to
carnivorous predators. Based on stable isotope analyses, we present evidence for a strong contribution of ‘new’ nitrogen mainly
derived from the utilization of aerosol nitrate by unicellular cyanobacteria especially during summer stratification and the
propagation of exceptionally low δ15N onto higher trophic levels. In contrast, N2-fixation by diazotrophs seemed to play a minor role, while the utilization of deep water nitrate by cyanobacteria and eukaryotic
algae might be of importance during winter mixing. Based on 15N enrichment of consumers, clear differences between exclusively herbivorous organisms (doliolids, appendicularians, pteropods)
and those with omnivorous feeding modes were detected. The category of omnivores comprised a large variety of taxons ranging
from small meroplanktonic larvae to non-calanoid copepods (harpacticoids, cyclopoids and poecilostomatoids) that together
form a diverse and complex community with overlapping feeding modes. In addition, distinct seasonality patterns in δ15N of copepods were found showing elevated trophic positions during periods of winter mixing, which were most pronounced for
non-calanoid copepods. In general, feeding modes of omnivores appeared rather unselective, and relative contributions of heterotrophic
protists and degraded material to the diets of non-calanoid copepods are discussed. At elevated trophic positions, four groups
of carnivore predators were identified, while calanoid copepods and meroplanktonic predators showing lowest 15N enrichment within the carnivores. The direct link between ‘new’ nitrogen utilization by primary producers and the 15N enrichment of consumers in the planktonic food web of the Gulf of Aqaba emphasizes the significant contribution of ‘new’
nitrogen to the nitrogen budget and ecosystem functions in subtropical and tropical oligotrophic oceans. 相似文献
6.
The distribution and abundance of transparent exopolymer particles (TEP) was determined in and below pack ice of the Laptev
Sea from July to September 1995. Samples were collected from the lowermost 10 cm of ice floes and at 10 cm below the ice–water
interface. Abundance of bacteria, protists and TEP was determined, and the sea ice–water boundary layer was characterized
using temperature, salinity and molecular viscous shear stress. TEP, with a distinct size distribution signal, were found
in highest concentrations inside the sea ice, ranging from not detectable to 16 cm2 l−1 (median: 2.9 cm2 l−1). In the water, concentrations were one order of magnitude lower, ranged from below detection to 2.7 cm2 l−1 (median: 0.2 cm2 l−1) and decreased after the middle of August, whereas abundances of autotrophic flagellates (AF), diatoms, heterotrophic flagellates
(HF) and ciliates increased. The abundance of TEP decreased with its size in all samples following a power law relationship.
The relation of TEP to the microbial community differed between the sea ice and water, being positively correlated with bacteria
and diatoms in the ice and negatively correlated with HF in the sea water. The presence of a pycnocline significantly influenced
the abundance of organisms, diatom composition and TEP concentrations. Pennate diatoms dominated by Nitzschia frigida were most abundant inside the ice. Though bacteria have the potential to produce exopolymeric substances (EPS), the results
of this study indicate that the majority of TEP at the ice–water interface in first-year Arctic summer pack ice are produced
by diatoms.
Received: 19 August 1999 / Accepted: 4 July 2000 相似文献
7.
Structured sampling designs are important in the assessment of environmental impacts of variable ecological systems. Recent developments have provided a useful framework extending existing univariate techniques into a multivariate context. Measures of taxonomic relatedness have also been introduced, which complement existing measures of diversity of assemblages. In this study, the potential effects of sewage discharge on spatial patterns of highly diverse molluscan assemblages in a Mediterranean rocky subtidal habitat were investigated. Nine 20 cm×20 cm quadrats were taken from each of three sites (80 m–100 m apart) within a putatively impacted location near a sewage outfall (I) and at each of two control locations (Cs) by destructive sampling by SCUBA divers at a depth of 3 m–4 m. A total of 5507 specimens of 151 species were collected. The average and the variance in total abundance of molluscs were greater, on average, at I than at Cs. Higher abundances at the sewage outfall were largely driven by greater numbers of juvenile molluscs. The Shannon diversity of molluscs (H′) was significantly lower at I, but no difference among locations was detected for the total number of species (S). In addition, the taxonomic distinctness (Δ*) of molluscs was greater at Cs, although it was more variable at I. Multivariate analyses showed that there was a significant difference in the structure of assemblages at I compared with Cs. The location near the outfall was characterized by greater abundances of several species, including especially the gastropods Pusillina philippi, Bittium latreilli, and Bittium reticulatum. There was also greater variability in the structure of assemblages among sites and among quadrats at control locations compared to those near the outfall. Using a suite of univariate and multivariate measures, including diversity indices, detailed information on taxonomic structure and analyses of variability at different spatial scales, provided useful insights into the effects of sewage impacts on these diverse assemblages. These results also highlighted the importance of analysing measures of variance, as well as mean in considering effects of stress in natural communities. 相似文献
8.
Fu-Lin Evelyn Chu Eric D. Lund Paul R. Littreal Kate E. Ruck Ellen Harvey Jean-René Le Coz Yanic Marty Jeanne Moal Philippe Soudant 《Marine Biology》2009,156(2):155-169
The kinetics and efficiency of sterol production and bioconversion of phytosterols in two heterotrophic protists Oxyrrhis marina and Gyrodinium dominans were examined by feeding them two different algal species (Rhodomonas salina and Dunaliella tertiolecta) differing in sterol profiles. R. salina contains predominantly brassicasterol (≅99%) and <2% cholesterol. The major sterols in D. tertiolecta are ergosterol (45–49%), 7-dehydroporiferasterol (29–31%) and fungisterol (21–26%). O. marina fed R. salina metabolized dietary brassicasterol to produce 22-dehydrocholesterol and cholesterol. O. marina fed D. tertiolecta metabolized dietary sterols to produce cholesterol, 22-dehydrocholesterol, brassicasterol and stigmasterol. G. dominans fed either R. salina or D. tertiolecta metabolized dietary sterols to make cholesterol, brassicasterol and a series of unknown sterols. When protists were fed R. salina, which contains cholesterol, the levels of cholesterol were increased to a magnitude of nearly 5- to 30-fold at the phytoplankton-heterotrophic
protist interface, equivalent to a production of 172.5 ± 16.2 and 987.7 ± 377.7 ng cholesterol per mg R. salina carbon consumed by O. marina and G. dominans, respectively. When protists were fed D. tertiolecta, which contains no cholesterol, a net production of cholesterol by the protists ranged from 123.2 ± 30.6 to 871.8 ± 130.8 ng
per mg algal C consumed. Cholesterol is not only the dominant sterol, but a critical precursor for many physiologically functional
biochemicals in higher animal. As intermediates, these heterotrophic protists increase the amount of cholesterol at the phytoplankton–zooplankton
interface available to higher trophic levels relative to zooplankton feeding on algae directly. 相似文献
9.
Gromia is a large marine protist with filose pseudopodia and ovoid test, common in coastal intertidal and sublittoral waters. Although
deep-water Gromia-like morphospecies were discovered in the 1990s, their relations to the shallow water species have never been established.
Moreover, very little is known about the diversity within Gromia, reflecting the fact that these morphologically relatively simple protists have few characters useful for species identification.
Consequently, we have analysed the SSU rDNA and ITS rDNA genes to examine gromiid diversity in two different areas located
on the Oman and Pakistan margins of the Arabian Sea (water depths 1,000–2,000 m). In total, 27 deep-sea gromiid sequences
of the SSU rDNA gene and six sequences of the ITS rDNA region were obtained. Our data confirm that Gromia-like protists from the bathyal deep sea are related to the shallow-water gromiids. Within Arabian Sea Gromia, we identified seven distinctive lineages, five of which form a monophyletic group branching as a sister group to shallow-water
species. Six lineages of Arabian Sea Gromia can be defined morphologically, while one lineage includes specimens that look identical to specimens from two other lineages.
This indicates that each Gromia lineage represents probably a separate species and suggests that deep-sea gromiid diversity is higher than indicated by their
simple morphology. 相似文献
10.
Mussel culture in coastal environments relies on the availability of food of sufficient quality and quantity. Both to determine
this availability and to examine impacts that this aquaculture practice may have on the environment, it is important to have
good knowledge of the type of plankton communities present in aquaculture sites. It is usually thought that phytoplankton
make up the bulk of mussel diet in many of these sites. Here we show that the Grande-Entrée lagoon [Magdalen Islands, Gulf
of St Lawrence (GSL), Canada], where commercial mussel culture has been on-going since 1980, differs from this pattern. Heterotrophic
protists dominate for most of the summer-early fall season (apart from short diatom bursts), with a high average biomass of
160 mg C m−3. The dominance of small-sized phytoplankton cells (notably green algae), low nutrient concentrations (e.g. 0.3 μM NO3− on average) and high biomass of heterotrophic protists (mostly naked ciliates and tintinnids) all point to the importance
of the microbial food web in this shallow marine environment. Sustained cultivation of suspended mussels in the lagoon suggests
that these heterotrophic protists could be an important source of food for the mussels, supplementing the small amount of
phytoplankton present. 相似文献
11.
This paper identifies newer areas of arsenic contamination in the District Kanker, which adjoins the District Rajnandgaon where high contamination has been reported earlier. A correlation with the mobile phase episodes of arsenic contamination has been identified, which further hinges on the complex geology of the area. Arsenic concentrations in both surface and groundwater, aquatic organisms (snail and water weeds) soil and vegetation of Kanker district and its adjoining area have been reported here. The region has been found to contain an elevated level of arsenic. All segments of the ecoysystem are contaminated with arsenic at varying degrees. The levels of arsenic vary constantly depending on the season and location. An analysis of groundwater from 89 locations in the Kanker district has shown high values of arsenic, iron and manganese (mean: 144, 914 and 371 μg L−1, respectively). The surface water of the region shows elevated levels of arsenic, which is influenced by the geological mineralised zonation. The most prevalent species in the groundwater is As(III), whereas the surface water of the rivers shows a significant contamination with the As(V) species. The analysis shows a bio-concentration of the toxic metals arsenic, nickel, copper and chromium. Higher arsenic concentrations (groundwater concentrations greater than 50 μg L−1) are associated with sedimentary deposits derived from volcanic rocks, hence mineral leaching appears to be the source of arsenic contamination. Higher levels of arsenic and manganese in the Kanker district have been found to cause impacts on the flora and fauna. A case study of episodic arsenical diarrhoea is presented. 相似文献
12.
Light regime in an Arctic fjord: a study related to stratospheric ozone depletion as a basis for determination of UV effects on algal growth 总被引:9,自引:0,他引:9
D. Hanelt H. Tüg K. Bischof C. Groß H. Lippert T. Sawall C. Wiencke 《Marine Biology》2001,138(3):649-658
Solar radiation as a primary abiotic factor affecting productivity of seaweeds was monitored in the Arctic Kongsfjord on
Spitsbergen from 1996 to 1998. The radiation was measured in air and underwater, with special emphasis on the UV-B (ultraviolet
B, 280–320 nm) radiation, which may increase under conditions of stratospheric ozone depletion. The recorded irradiances were
related to ozone concentrations measured concurrently in the atmosphere above the Kongsfjord with a balloon-carried ozone
probe and by TOMS satellite. For comparison, an ozone index (a spectroradiometrically determined irradiance of a wavelength
dependent on ozone concentration, standardized to a non-affected wavelength) was used to indicate the total ozone concentration
present in the atmosphere. Weather conditions and, hence, solar irradiance measured at ground level were seldom stable throughout
the study. UV-B irradiation was clearly dependent on the actual ozone concentration in the atmosphere with a maximal fluence
rate of downward irradiance of 0.27 W m−2 on the ground and a maximal daily fluence (radiation exposure) of 23.3 kJ m−2. To characterize the water body, the light transmittance, temperature and salinity were monitored at two different locations:
(1) at a sheltered shallow-water bay and (2) at a wave-exposed, deep-water location within the Kongsfjord. During the clearest
water conditions in spring, the vertical attenuation coefficient (K
d) for photosynthetically active radiation (PAR) was 0.12 m−1 and for UV-B 0.34 m−1. In spring, coinciding with low temperatures and clear water conditions, the harmful UV radiation penetrated deeply into
the water column and the threshold irradiance negatively affecting primary plant productivity was still found at about 5–6 m
depth. The water body in spring was characterized as a Jerlov coastal water type 1. With increasing temperature in summer,
snow layers and glacier ice melted, resulting in a high discharge of turbid fresh water into the fjord. This caused a stratification
in the optical features, the salinity and temperature of the water body. During melt-water input, a turbid freshwater layer
was formed above the more dense sea water. Under these conditions, light attenuation was stronger than defined for a Jerlov
coastal water type 9. Solar radiation was strongly attenuated in the first few metres of the water column. Consequently, organisms
in deeper water are protected against harmful UV-B radiation. In the surface water, turbidity decreased when rising tide caused
an advection of clearer oceanic water. In the course of the summer season, salinity continuously decreased and water temperature
increased particularly in shallow water regions. The impact of global climate change on the radiation conditions under water
and its effects on primary production of seaweeds are discussed, since organisms in the eulittoral and upper sublittoral zones
are affected by UV radiation throughout the polar day. In clearer water conditions during spring, this may also apply to organisms
inhabiting greater depths.
Received: 20 June 2000 / Accepted: 17 October 2000 相似文献
13.
This study describes the activities of the key enzymes involved in carbon incorporation (carbonic anhydrase, CA) and inorganic
nitrogen reduction (nitrate reductase, NR) in 25 intertidal macroalgae of southern Chile (39°S). UV radiation as a factor
affecting the nutrient metabolism of algae was also examined. The results of the enzyme activities and the UV sensitivity
were related to the position of the algae on the shore, species/taxonomic groups and morpho-functional patterns. The CA activity
in the studied algae ranged from 42 to 165 REA g−1 FW, and was neither related to growing depth nor to taxonomic or morpho-functional groups. The NR activities ranged from
0.1 to 8.9 μmol NO2− g−1 FW min−1, with the highest levels observed in red algae. In contrast to CA, the NR activities showed a decreasing tendency from supra/midlittoral
to infra/sublittoral. Also, differences between morpho-functional groups were seen. The impact of artificial UV radiation
on CA and NR activities was variable as in some species it provoked an increase while in other species a decrease was observed,
suggesting species-specific responses and UV sensitivity. The CA activity was the most UV sensitive in the taxonomic group
Chlorophyta and in the supralittoral algae. The UV sensitivity of NR activity could not be related to any patterns related
to morpho-functional or taxonomic groups and habitat depth. 相似文献
14.
Dietary information obtained from stomach contents can provide a wealth of information on an animal’s ecology. Where animals
are cryptic, such as the post-hatchling life history stage of a sea turtle, the ecological insight that dietary analyses can
provide, may be otherwise unobtainable. Investigations into post-hatchling turtle stomach contents have found planktonic organisms,
dominated by pelagic molluscs and crustaceans, hydrozoans, Sargassum and fish eggs. The nature of these dietary organisms provides evidence for the widely accepted hypothesis that, with the
exception of the flatback turtle (Natator depressus), the post-hatchling stage of a sea turtle’s life history is pelagic and oceanic. As the majority of studies that have investigated
the stomach contents of post-hatchling sea turtles have been conducted on loggerhead turtles (Caretta caretta) in the northern Atlantic and Pacific Oceans, insight derived from dietary investigations into post-hatchling ecology is
biased. This study investigates the diet of post-hatchling green turtles (Chelonia mydas) and loggerhead turtles in the southwest Pacific Ocean. Stomach contents were obtained from 55 green and loggerhead post-hatchling
turtles that had stranded or been consumed by Coryphaena hippurus. Our findings demonstrate that loggerhead and green post-hatchlings in the southwest Pacific share similar feeding ecology
and feed on a variety of neustonic items that are indicative of an oceanic and pelagic existence. The dietary items consumed
by both species investigated belong to similar taxonomic groups as those found in previous studies with species level distinctions
occurring owing to the different geographical location. 相似文献
15.
Spatio-temporal patterns in the diversity of demersal fish communities off the south coast of South Africa 总被引:3,自引:0,他引:3
The diversity of ecological communities has been the focus of many studies. Because biodiversity provides several indicators
used in an Ecosystem Approach to Fisheries (EAF) to track changes in fish communities, we investigated the spatial and temporal
patterns in the diversity of some demersal fish communities subjected to varying fishing pressure. Depth and catch rate were
the most important predictors in explaining changes in diversity followed by longitude and survey year. Diversity, as measured
by the various indices except for taxonomic distinctness (∆*), initially declined with increasing depth to about a depth of
80 m, then increased to about 150 m after which it declined. Taxonomic distinctness index (∆*) showed an increase in the taxonomic
heterogeneity of the demersal community below the 300-m isobath. Diversity remained relatively constant with increase in longitude
to around 24°E (which has the lowest diversity) after which it increased. The assessment of the temporal trend in diversity
indicates that survey year has a significant effect on all diversity indices except for ∆*. Diversity increased and dominance
declined with time. This may be result of a decline in the abundance of dominant species or an increase in the abundance less
dominant species, or a combination of both effects. Multivariate analysis of the set of diversity indices showed three groups
of indices: those reflecting species richness (S, Margalef’s d), those measuring mainly taxonomic relatedness (∆*), and those balancing the richness and evenness components of diversity
(J′, H′, λ, ∆, Hill’s N1, and Hill’s N2). The relationship between evenness, catch rate, and size was also investigated. Size classes with highest evenness were
found to have lowest catch rate and vice versa. This highlights the need to consider the size and trophic level of species
when linking diversity to the functioning of ecosystems. 相似文献
16.
E. A. Widder S. Johnsen S. A. Bernstein J. F. Case D. J. Neilson 《Marine Biology》1999,134(3):429-437
To learn how organisms apportion space in the open ocean, biological oceanographers have sought to improve temporal and spatial
resolution of ocean sampling systems. Their objectives are to simultaneously measure physical, chemical and biological structure
in the water column in order to find significant correlations that may reveal underlying processes. Here we report one such
correlation between intense peaks of bioluminescence and density discontinuities in the water column. Intensified video recordings
made in these bioluminescent “hot spots” were analyzed with a computer image-recognition program that identifies organisms
based on the temporal and spatial characteristics of their luminescent displays. Based on this analysis, the source of the
“hot spots” was found to be very thin layers (0.5 m) of the bioluminescent copepod Metridia lucens present at from 5 to 100 times average background concentrations. Given the recent discovery that the vertical distribution
of marine snow is also strongly correlated with density discontinuities in the water column, we suggest that this finding
may provide a possible explanation for the disparity between estimated energy requirements of marine copepods and measurements
of average in situ food concentrations. The energy costs associated with locating food-rich micro-patches is greatly reduced
if those patches are spread out into very thin layers, because the search strategy can be reduced from three dimensions to
one.
Received: 28 December 1998 / Accepted: 12 April 1999 相似文献
17.
Biomass partitioning of benthic microbes in a Baltic inlet: relationships between bacteria, algae, heterotrophic flagellates and ciliates 总被引:6,自引:0,他引:6
The structure of a benthic microbial food web and its seasonal changes were studied in the shallow brackish waters of the
island of Hiddensee, northeastern Germany, at two sites in close proximity by monthly or bimonthly sampling from July 1995
to June 1996. Abundance and biomass of phototrophic and non-phototrophic bacteria, heterotrophic flagellates (HF) and ciliates
as well as the biomass of microphytobenthos were determined in the upper 0.3 cm sediment layer. Abundance of organisms showed
strong positive correlation with water temperature, with the exception of the bacteria. Non-phototrophic bacterial numbers
ranged from 7 × 108 to 6.7 × 109 cells cm−3 and phototrophic bacterial abundance from 4 × 107 to 2.7 × 108. Heterotrophic protist abundance ranged from 8 × 103 to 104 × 103 ind cm−3 for HF and from 39 to 747 ind cm−3 for ciliates. The biomass partitioning demonstrated the primary importance of non-phototrophic bacteria (min. 0.83, max.
84.87 μg C cm−3), followed by the microphytobenthos (min. 1.32, max. 50.93 μg C cm−3). The heterotrophic protists contributed roughly the same fraction to the total microbial biomass, with the biomass of the
HF being slightly higher (HF 0.23 to 1.76 μg C cm−3, ciliates 0.04 to 1.17 μg C cm−3). Taxonomic classification of the benthic HF revealed the euglenids to be the most important group in terms of abundance
and biomass, followed by thaumatomastigids and kinetoplastids. Other important groups were apusomonads, cercomonads, pedinellids
and cryptomonads. The structure of the HF assemblage showed strong seasonal changes with euglenids being the most abundant
taxa in summer, while apusomonads and thaumatomastigids were predominant in winter. Similar to the pelagic microbial food
web, benthic picophototrophic bacteria were occasionally abundant, and the feeding modes of heterotrophic protists exhibited
a great variety (predominantly omnivores, bacterivores, herbivores or predators). Filter-feeding HF were of little importance.
Contrary to the pelagic environment, a top-down control on total benthic bacterial numbers by HF seemed unlikely at the studied
stations which were characterised by muddy sand.
Received: 6 January 1999 / Accepted: 21 October 1999 相似文献
18.
S. M. Tong 《Marine Biology》1997,128(3):517-536
The diversity of heterotrophic flagellates in the water column at Denham, in Shark Bay, Western Australia, was examined in
April 1995 by observations of living cells in freshly collected samples, and in enrichment cultures. Observations were also
made of cells on whole-mount preparations, using light and electron microscopy. A total of 41 species are described, drawn
from the apusomonads, cercomonads, choanoflagellates, cryptomonads, euglenids, heteroloboseids, stramenopiles and groups of
uncertain taxonomic affinities (Protista incertae sedis). A new species, Percolomonas denhami, is described and assigned to the Heterolobosea. Three-quarters of the species seen have not previously been reported from
southern sub-tropical regions. The biogeography of the species seen in Western Australia is discussed with reference to studies
in other localities. It appears that many heterotrophic flagellates have a cosmopolitan distribution.
Received: 11 June 1996 / Accepted: 13 December 1996 相似文献
19.
T. Meziane S. Y. Lee P. L. Mfilinge P. K. S. Shin M. H. W. Lam M. Tsuchiya 《Marine Biology》2007,150(6):1103-1113
Fatty acid compositions of the leaves of six species of mangroves were studied to ascertain their use as biomarkers for determining
the fate of mangrove organic matter in the habitat and as taxonomic tool. Mangrove leaves were collected from three locations
in the western Pacific Ocean: Moreton Bay (MB) (Australia), Hong Kong (China) and Okinawa (Japan). In MB, samples were collected
from two sites separated by 15 km: Logan River Estuary (LRE) and Jabiru Island. In addition, along the LRE, leaves were collected
from five stations at ∼2–3 km apart. Results show that the analysis of the entire fatty acid profiles of the mangrove leaves
is a promising taxonomic tool as the profiles of most species were sufficiently different to be separated in an non-metric
multidimensional scaling plot. In addition, geographically separated populations of the same species could also be identified
by their fatty acid profiles. In most cases, two non-ubiquitous groups of fatty acids dominated in the mangrove leaves: the
polyunsaturated 18:2ω6 and 18:3ω3 and the long chain fatty acids (≥24:0). With respect to the relative contributions of these
fatty acids, three groups of species were identified, in which one or both groups of fatty acids may potentially be used as
markers of the mangrove organic matter in the estuarine environment. 相似文献
20.