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111.
Anastasija?ZaikoEmail author Darius?Daunys Sergej?Olenin 《Helgoland Marine Research》2009,63(1):85-94
Habitat engineering role of the invasive zebra mussel Dreissena polymorpha (Pallas) was studied in the Curonian lagoon, a shallow water body in the SE Baltic. Impacts of live zebra mussel clumps and
its shell deposits on benthic biodiversity were differentiated and referred to unmodified (bare) sediments. Zebra mussel bed
was distinguished from other habitat types by higher benthic invertebrate biomass, abundance, and species richness. The impact
of live mussels on biodiversity was more pronounced than the effect of shell deposits. The structure of macrofaunal community
in the habitats with >103 g/m2 of shell deposits devoid of live mussels was similar to that found within the zebra mussel bed. There was a continuous shift
in species composition and abundance along the gradient ‘bare sediments—shell deposits—zebra mussel bed’. The engineering
impact of zebra mussel on the benthic community became apparent both in individual patches and landscape-level analyses. 相似文献
112.
We examined the microhabitat determinants of the benthic goby Rhinogobius sp. OR (orange form) in runs by measuring fish density, and substrate and hydraulic variables at four sites in the middle
and lower reaches of the Ado River, Japan. One of the four sites was located below a bridge pier in the lower reach and had
coarser substrate than was typical there. This contributed to the elimination of the correlation between substrate condition
and hydraulic variables by providing anomalous combinations of substrate and hydraulic variables. Using principal component
analysis, the variables were divided into substrate and hydraulic components. A multiple regression analysis revealed that
substrate variables explained more of the variance in fish density than hydraulic variables. We concluded that the density
of this goby is determined by substrate conditions in runs, where the current velocity is lower and the stone shelter is scarcer
than in riffles. The importance of substrate conditions, which can be easily masked by current velocity in natural settings,
should not be neglected. 相似文献
113.
In an attempt to decipher the biotic response of Foraminifera to the paleoenvironmental changes recorded in the Aptian historical stratotypes, a number of quantitative parameters (i.e. specific diversity and abundance of dominant groups) were examined in three sections of upper Bedoulian and lower Gargasian beds in south-eastern France. In most cases, the established biotic changes do not correlate strictly with obvious lithological and geochemical variations such as the percentage of CaCO3 and δ13C. However, a pattern of cyclic fluctuations in various microfaunal parameters appears to exist in parts of the studied interval, which may record paleoenvironmental changes due to a cyclic orbital forcing. To test this hypothesis, based on a preliminary study, a more closely spaced sampling of these continuous, expanded and relatively well calibrated stratotypic series is required. 相似文献
114.
Long term changes of biodiversity of benthic macroalgae in the intertidal zone of the Nanji Islands 下载免费PDF全文
A long term observation on biodiversity and biomass of benthic macroalgae in Point 1 of the intertidal zone of the Nanji Islands, Zhejiang were carried out during 1959–2007, including three phases, i.e. 1959–1965, 1980–1985 and 2000–2007. The results show that the species of the benthic macroalgae there disappeared by 41.7%, and decreasing trend of the biodiversity has been getting quick; the community structure clearly shifted, i.e. the proportion of subtropical and warm-temperate species increased, and that of cold-temperate species decreased in the benthic macroalgae assemblage, particularly the calcareous nullipore became an absolutely dominant group. In comparison with the second phase (1980–1985), during the third phase the average annual biomass of the benthic macroalgae decreased by 52.5%; the average spring and winter biomass decreased by 54.1% and 87.2%; while the average summer and autumn biomass increased by 11.1% and 3.2%, respectively. The causes of the decrease in the biodiversity have been discussed, and the authors considered that the climate change and increase in CO2 concentration have been the main reasons to lead berserk growth of the nullipore, resulting in desertification tendency of the intertidal zone of the Nanji Islands. 相似文献
115.
The examination of macrophyte, water and sediment samples, collected at depths less than 1.5 m from 50 different sites along the North Aegean coasts, has revealed, for the first time in Greek coastal waters, the presence of two Ostreopsis species (O. ovata and O. cf. siamensis) and Coolia monotis in the majority of the sampling sites (94% and 100%, respectively). Other epiphytic dinoflagellates of the genera Prorocentrum and Amphidinium and diatoms were accompanying species in this epiphytic community. Morphometric features, plate formula and thecal ornamentation were used for species identification. O. ovata cells were smaller in dorsoventral (DV) diameter and width (W) (26.18–61.88 μm and 13.09–47.60 μm, respectively) in comparison with O. cf. siamensis (35.70–65.45 μm and 23.80–49.98 μm, respectively). In contrast, the anterioposterior (AP) diameter of O. cf. siamensis was smaller (14.28–26.18 μm) resulting in DV/AP ≈ 3, whereas the above ratio for O. ovata was less than 2 (AP ranging between 14.28–35.70 μm). Moreover, the theca of O. ovata cells was ornamented with scattered pores, which fluctuated in a wider range (0.07–0.32 μm) than those of O. cf. siamensis (0.23–0.29 μm). Coolia monotis cells were almost round with average DV diameter 26.88 μm, AP 25.66 μm and width 26.76 μm. Small and large cells were recorded in both field and culture populations of Ostreopsis spp. and C. monotis, while hyaline cysts were observed for O. ovata. The presence of O. ovata and O. cf. siamensis exhibited a clear seasonal pattern dominating (maximum abundance up to 4.05 × 105 cells gr−1 fwm) the period from midsummer to late autumn in years 2003 and 2004, while C. monotis was found also in winter and spring months. 相似文献
116.
Using a large experimental channel, five artificial high flows with different flow regimes were launched to reveal the precise
temporal sequences of drifting particulate matter and organisms during the high flows. Drifting fine particulate matter and
organisms were collected by sampling bottles and a water pump, respectively. The peaks of drift abundance occurred before
the peak discharges, and the abundance declined quickly within several minutes during the rising phase of high flows. The
major determinant of drift abundance of particulate matter and organisms was periods of stable conditions before each high
flow (tested by determination coefficients in a correlation analysis). The drift of macroscopic plant material also accelerated
the drifts of epiphytic fauna and infauna, which drifted with plants and bed sediments. The magnitude (discharge and duration
of peak flows) of high flows only slightly affected drift abundance. The fauna more resistant to high flows were invertebrates
that fasten their cases or retreats by silk threads on the substrata. Invertebrate taxa having sucking apparatus or high swimming
activity were also resistant to high flows. 相似文献
117.
Sushchik NN Gladyshev MI Kalachova GS Makhutova ON Ageev AV 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2006,145(3-4):278-287
Seasonal dynamics of contents of essential polyunsaturated fatty acids (PUFA) in dominant groups of benthic invertebrates: gammarids (Gammaridae, Amphipoda), oligochaetes (Oligochaeta), chironomid larvae (Chironomidae, Diptera) and caddisfly larvae (Trichoptera), and dominant benthivorous fish, Siberian grayling Thymallus arcticus, have been studied in ecosystem of the large Siberian river. During the year of the study most benthic invertebrate taxa showed significant variations in the contents of both C-18 and long chain C-20–22 PUFAs. In contrast, the fish, which consumed the zoobenthos, had no significant seasonal variations in long chain PUFAs' contents. Thereby, the fish, as organisms of relatively higher evolution level than invertebrates, was supposed to have more strict metabolic control of long chain PUFAs' contents. Evidence was obtained that the studied fish species, grayling, may be capable to convert dietary EPA into DHA. 相似文献
118.
Spatial patterns and ecology of benthic communities on a high-latitude South Florida (Broward County,USA) reef system 总被引:1,自引:0,他引:1
Ryan?P.?MoyerEmail author Bernhard?Riegl Kenneth?Banks Richard?E.?Dodge 《Coral reefs (Online)》2003,22(4):447-464
High-latitude reef communities consisting of typical Caribbean fauna of variable composition and density exist on four parallel ridges at varying depths along the Broward County (Florida, USA) coast. Two of these ridges, at 7–13 and 15–30 m in depth, are drowned early Holocene coral reefs of 5 and 7 ky uncorrected radiocarbon age. In this study, community data were collected on each reef using 50-m, line-intercept transects. Using multivariate non-metric statistics, the data show distinct differences in benthic community structure across several spatial gradients. Diversity indices revealed that while all values were low, species diversity (H) was consistent throughout the county, and species richness (d) and evenness (J) increased along a north-south gradient. Scleractinian coral (27 species) cover was low (<6%) in all areas, and Montastrea cavernosa dominated as the major hermatypic scleractinian. Notably absent was the major Caribbean reef-builder Acropora palmata. A rich alcyonacean fauna was present on all studied reefs, and these were typically the most important faunal group determining community structure. Although during the 2-year period 2000–2002 mean water temperatures never fell below 20 °C, scleractinia were small in size. 相似文献
119.
Ashraf Mohamed Samir Hosny Farid AbdouSamiha Mahmoud Zazou Wafaa Hashem El-Menhawey 《Revue de Micropaléontologie》2003,46(2):111
A suite of 74 surface sediment samples, collected from two areas along the Egyptian Mediterranean coast (the Western Harbor of Alexandria and its environs, and the area comprising the Gulf of Kanayis and the Abu Hashafa Bay), have been examined for their benthic foraminiferal faunas. A total of 82 species were identified. Census data were obtained for different species in each sample and the statistically significant fractional abundances values (≥5%) were analyzed using a Q-mode cluster analysis. Samples were segregated into four clusters, each having its peculiar benthic faunal assemblage (biotope), reflecting particular environmental conditions. These clusters are: (1) the Ammonia beccarii forma tepida Biotope, found in samples located in areas with waters of low energy, characterizing semi-closed basin conditions, with muddy or sandy mud bottom sediments (Harbor Proper); (2) the Quinqueloculina spp. Biotope, found in samples collected from depths bathed by turbid inner shelf conditions with some fresh water inflow and sandy bottom sediments (Harbor’s environs); (3) the Peneroplis-Amphistegina Biotope, found in samples collected from depths characterizing marine shelf environments with calcareous algae, and medium to very coarse calcareous sands (the Gulf of Kanayis and the Abu Hashafa Bay); (4) the Triloculina trigonula-Adelosina laevigata Biotope was represented by only one sample (at the far eastern part of the Gulf of Kanayis), collected from a site exhibiting very restricted environmental conditions. The study suggests that nutrients, turbidity, light intensity, type of substrate, and salinity are the main ecological factors controllingthe distribution of benthic foraminifera. 相似文献
120.
Paleodictyoconus actinostoma, a new species ofprimitive orbitolinid foraminifera from the neritic Lower Aptian of Vercors (Isère Dep., SE France) is described and figured. This new form derives probably from P. barremianus (Moullade); the differences between the two species are described. P. cuvillieri (Foury) is regarded as a synonym of P. barremianus. 相似文献