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1.
The summer Phaeocystis antarctica bloom increases under-ice phytoplankton biomass in McMurdo Sound, Antarctica. The magnitude of mesozooplankton grazing on
this bloom is unknown, and determines whether this production is available to the pelagic food web. We measured mesozooplankton
abundance and body content of dimethylsulfoniopropionate (DMSP) during the McMurdo Sound austral summer (2006 and 2006–2007).
Abundance varied from 20 to 4,500 ind. m−3 (biomass 0.02–274.0 mg C m−3), with peaks in mid-December and late-January/February. Abundance was higher but total zooplankton biomass lower in our study
compared to previous reports. Copepods and the pteropod Limacina helicina dominated the zooplankton in both abundance and biomass. DMSP was detected in all zooplankton groups, with highest concentrations
in copepod nauplii and L. helicina (95 and 54 nmol mg−1 body C, respectively). Experiments suggested that L. helicina obtains DMSP by directly grazing on P. antarctica, which often accumulates to high biomass under the summer sea ice in McMurdo Sound. 相似文献
2.
Population dynamics and production of the freshwater snail Chilina gibbosa Sowerby 1841 (Chilinidae,Pulmonata) in a North-Patagonian reservoir 总被引:1,自引:1,他引:0
Chilina gibbosa is an endemic snail widely distributed in Patagonia, Argentina. Due to its importance in the benthic fauna and in the diet
of some fish in the oligo-mesotrophic reservoir Ezequiel Ramos Mexía (39° 30′ S, 69° 00′ W), special attention has been given
to its life cycle, growth patterns and annual production. Samples were taken monthly at five littoral stations between June
1983 and July 1984.
Mean abundance and biomass of C. gibbosa were much higher in vegetated stations dominated by Potamogeton berteroanus (Station 1 : 583 ind. m−2, 5.95 g AFDM m−2) or by Nitella clavata (Station 5 : 275 ind. m−2, 4.18 g AFDM m−2) than bare stations with low transparency or stations with other macrophytes. The snails presented a clustered spatial pattern
and their abundance was significantly correlated with macrophyte wet biomass only when this was above 250 g m−2. Analysis of size distributions showed an annual life cycle with a reproductive period in the summer. However, differences
in recruitment and growth occurred probably due to differences in water temperature and food availability. Growth was maximum
in summer and almost absent during winter. Hence, shell growth data fit a sigmoid curve well, and growth was somewhat higher
at Station 1. Annual production at Stations 1 and 5, estimated by the ‘growth increment summation’ method (28.8 g AFDM m−2 and 14.18 g AFDM m−2 respectively), was among the highest recorded for pulmonate gastropods, possibly due to a low interspecific competition.
The P : B ratio values were within the range for univoltine gastropods (4.84 and 3.39).
The high productivity and turnover rate of these snails grant a high availability of food for the abundant molluscivore, the
silverside Patagonina hatcheri. 相似文献
3.
Energy flow and subsidies associated with the complex life cycle of ambystomatid salamanders in ponds and adjacent forest in southern Illinois 总被引:1,自引:0,他引:1
Breeding adults and metamorphosing larval amphibians transfer energy between freshwater and terrestrial ecosystems during
seasonal migrations and emergences, although rarely has this been quantified. We intensively sampled ambystomatid salamander
assemblages (Ambystoma opacum,A. maculatum, and A. tigrinum) in five forested ponds in southern Illinois to quantify energy flow associated with egg deposition, larval production, and
emergence of metamorphosed larvae. Oviposition by female salamanders added 7.0–761.4 g ash-free dry mass (AFDM) year−1 to ponds (up to 5.5 g AFDM m−2 year−1). Larval production ranged from 0.4 to 7.4 g AFDM m−2 year−1 among populations in three ponds that did not dry during larval development, with as much as 7.9 g AFDM m−2 year−1 produced by an entire assemblage. Mean larval biomass during cohort production intervals in these three ponds ranged from
0.1 to 2.3 g AFDM m−2 and annual P/B (production/biomass) ranged from 4 to 21 for individual taxa. Emergent biomass averaged 10% (range=2–35%) of larval production;
larval mortality within ponds accounted for the difference. Hydroperiod and intraguild predation limited larval production
in some ponds, but emerging metamorphs exported an average of 70.0±33.9 g AFDM year−1 (range=21.0–135.2 g AFDM year−1) from ponds to surrounding forest. For the three ponds where larvae survived to metamorphosis, salamander assemblages provided
an average net flux of 349.5±140.8 g AFDM year−1 into pond habitats. Among all ponds, net flux into ponds was highest for the largest pond and decreased for smaller ponds
with higher perimeter to surface area ratios (r
2 =0.94, P<0.05, n=5). These results are important in understanding the multiple functional roles of salamanders and the impact of amphibian
population declines on ecosystems.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users. 相似文献
4.
Southwest Greenland provides wintering grounds for 70% (∼460,000) of the northern common eider (Somateria mollissima borealis) population. From 241 gullet samples (esophagus and proventriculus content) collected over three winters (1999–2002) near Nuuk, we identified 39 species consumed by the eiders. In contrast to studies elsewhere, fresh mass of the diet was dominated by soft-bottom species: the bivalve Mya eideri (32.8%) and the polychaete Pectinaria spp. (24.2%). The hard-bottom blue mussel (Mytilus edulis), usually the dominant prey of common eiders, was only the fourth most important diet species (7.5%). Overall, bivalves accounted for 56% of the diet. Twenty-seven prey species were minor foods with aggregate fresh mass of only 5.5%. Diets of males and females were similar, whereas juveniles consumed greater mass of crustaceans and less of bivalves. Diet diversity was higher in mid-winter than late winter, and higher in coastal habitats than in fjords. Within one important wintering area the results indicate that optimal size of blue mussels may be depleted over winter. 相似文献
5.
We studied life history and secondary production of a caddisfly scraper, Glossosoma nigrior, in two Alabama streams. Collier Creek, located within the Appalachian Plateau physiographic province, is underlain by sandstone
bedrock, while Hendrick Mill Branch is located in the Valley and Ridge physiographic province with limestone bedrock. G. nigrior populations in both streams exhibited trivoltine life histories, which were attributed to the higher water temperature regimes
than those found in more northern streams. Mean larval density (556 m−2) and biomass (B) (49.2 mg AFDM m−2) were much higher in Hendrick Mill Branch than Collier Creek (78 m−2 and 6.7 mg AFDM m−2). G. nigrior in Hendrick Mill Branch maintained continuous larval growth and higher larval density than Collier Creek throughout the year
mainly due to a greater availability of optimal habitat, a more stable hydrology, and warmer winter water temperature. These
factors also resulted in the much higher annual secondary production (P) in Hendrick Mill Branch (965 mg AFDM m−2; P/B = 18.3) than Collier Creek (115 mg AFDM m−2; P/B = 17.9). Gut content analysis revealed that algae (>50%) and detritus (>40%) were the major diet items for G. nigrior, and the majority of secondary production (>80%) was contributed by the consumption of algae. Glossosoma populations play an important role in trophic linkage in these streams with their high production and grazing activities.
Handling editor: D. Dudgeon 相似文献
6.
BROCK M. HUNTSMAN MICHAEL P. VENARSKY JONATHAN P. BENSTEAD ALEXANDER D. HURYN 《Freshwater Biology》2011,56(9):1746-1760
1. Surface ecosystems provide the primary source of organic matter to many cave communities. Variation in the strength of connectivity to the surface suggests that some caves may be more resource‐limited than others. To test this, we examined diet, prey availability and production of an obligate cave salamander Gyrinophilus palleucus (Plethodontidae), a top predator, in two south‐eastern U.S.A. caves with different levels of organic matter (Tony Sinks cave, 165 g AFDM m?2; Bluff River cave, 62 g AFDM m?2). 2. We quantified density, biomass, growth rate, production and diet of G. palleucus monthly for 21 months. Diet composition, differences in prey communities and seasonal patterns in prey consumption were also analysed. 3. Salamander density, biomass and secondary production were significantly greater in the high organic matter cave (0.10 m?2, 0.18 g AFDM m?2, 0.12 g AFDM m?2 year?1) than in the low organic matter cave (0.03 m?2, 0.03 g AFDM m?2, 0.01 g AFDM m?2 year?1). Although growth rates were not statistically different between the two cave salamander populations, low recaptures probably influenced this result. 4. Isopoda prey were the major contributor to salamander production in the high organic matter cave (69%). In the low organic matter cave, production was provided by isopods (41%) and oligochaetes (20%). The lower number of prey taxa contributing to salamander production in the high organic matter cave suggests the ability to forage more selectively. 5. The differences in foraging strategy, density, biomass and secondary production were probably related to differences in the strength of surface connectivity, which controls organic matter supply. Links between basal resource level and top predator performance show the importance of bottom‐up limitation in the food webs of caves and other detritus‐based ecosystems. 相似文献
7.
Coastal and offshore waters of Southwest Greenland are internationally important wintering areas for king eiders (Somateria spectabilis) breeding in eastern Canadian Arctic and in northwestern Greenland. This paper presents the first assessment of their winter
diet. Based on esophageal-proventricular samples from 26 females (13 juveniles and 13 older birds) and 15 males (11 juveniles
and four older birds) collected in 2000–2002 (November–May) in coastal waters of Nuuk, we identified 28 prey species. The
diet consisted of almost equal proportions (aggregate fresh mass) of polychaetes, echinoderms, crustaceans and molluscs. The
dominant prey species were Pectinaria spp. (26.8%), Strongylocentrotus droebachiensis (18.4%), Mya eideri (11.2%) and Hyas araneus (9.7%). The polychaetes have previously been identified as important prey for eiders in Greenland, but apparently not outside
Greenland. Compared with a diet study of common eiders Somateria mollissima from the same wintering area, the king eiders consumed significantly less bivalves and significantly more echinoderms. This
difference corresponded with observations that common eiders were feeding in shallow waters, while king eiders were feeding
in deeper waters farther from the shore. Benthic surveys are needed to confirm that diet corresponds with prey availability. 相似文献
8.
Photosynthetic performance in Sphagnum transplanted along a latitudinal nitrogen deposition gradient 总被引:1,自引:1,他引:0
Gustaf Granath Joachim Strengbom Angela Breeuwer Monique M. P. D. Heijmans Frank Berendse Håkan Rydin 《Oecologia》2009,159(4):705-715
Increased N deposition in Europe has affected mire ecosystems. However, knowledge on the physiological responses is poor.
We measured photosynthetic responses to increasing N deposition in two peatmoss species (Sphagnum balticum and Sphagnum fuscum) from a 3-year, north–south transplant experiment in northern Europe, covering a latitudinal N deposition gradient ranging
from 0.28 g N m−2 year−1 in the north, to 1.49 g N m−2 year−1 in the south. The maximum photosynthetic rate (NPmax) increased southwards, and was mainly explained by tissue N concentration, secondly by allocation of N to the photosynthesis,
and to a lesser degree by modified photosystem II activity (variable fluorescence/maximum fluorescence yield). Although climatic
factors may have contributed, these results were most likely attributable to an increase in N deposition southwards. For S. fuscum, photosynthetic rate continued to increase up to a deposition level of 1.49 g N m−2 year−1, but for S. balticum it seemed to level out at 1.14 g N m−2 year−1. The results for S. balticum suggested that transplants from different origin (with low or intermediate N deposition) respond differently to high N deposition.
This indicates that Sphagnum species may be able to adapt or physiologically adjust to high N deposition. Our results also suggest that S. balticum might be more sensitive to N deposition than S. fuscum. Surprisingly, NPmax was not (S. balticum), or only weakly (S. fuscum) correlated with biomass production, indicating that production is to a great extent is governed by factors other than the
photosynthetic capacity. 相似文献
9.
To understand the background of the strong variation and recent decline of stocks and production of mussels (Mytilus edulis) on tidal flats of the Wadden Sea, we analysed long-term (twice-annual for 26 years) and multi-station (15 sites) estimates
of numbers, mean individual weights, biomass, and annual production on Balgzand, a 50-km2 tidal-flat area in the westernmost part of the Wadden Sea (The Netherlands). Somatic production was estimated from summed
growth increments of soft tissues per half-year period and expressed in ash-free dry mass (AFDM). In adults, positive values
in spring/summer regularly alternated with negative values in autumn/winter, when up to ∼25% (mean: 14%) of individual weight
gains in the preceding season were lost. No weight losses were observed during the first winter of the life of mussels. The
26-year mean of net somatic tissue production P amounted to 5.5 g AFDM m−2 a−1 at a mean biomass B of 3.2 g AFDM m−2; the ratio P/B varied strongly with age composition of the mussel population and ranged between 0.5 and 3.0 a−1 (mean: 1.7). Within the restricted areas of mussel beds, mean biomass and annual production values were two orders of magnitude
higher. In the Wadden Sea, mussel beds cover a typical 1% of extensive tidal flat areas. Numerical densities of recruits showed
straight-line relationships with subsequent life-time year-class production. Once recruits had reached an age of ∼10 months,
their numbers predicted subsequent production within narrow limits. Production per recruit averaged 0.21 g AFDM for 10-mo
recruits and was not related to recruit density. Local variation in annual production varied strongly, with maximal values
between mid-tide and low-tide level, where recruitment was also maximal. Production per recruit was higher at low than at
high intertidal levels. Frequently failing recruitment is indicated as the main cause of declining mussel stocks in the Wadden
Sea. As in other bivalve species, a declining frequency of the occurrence of cold winters appears to govern declining recruitment
success and consequently declining production. 相似文献
10.
Secondary production and diet of an invasive snail in freshwater wetlands: implications for resource utilization and competition 总被引:1,自引:0,他引:1
Invasive species can monopolize resources and thus dominate ecosystem production. In this study we estimated secondary production
and diet of four populations of Pomacea canaliculata, a freshwater invasive snail, in wetlands (abandoned paddy, oxbow pond, drainage channel, and river meander) in monsoonal
Hong Kong (lat. 22°N). Apple snail secondary production (ash-free dry mass [AFDM]) ranged from 165.9 to 233.3 g m−2 year−1, and varied between seasons. Production was lower during the cool dry northeast monsoon, when water temperatures might have
limited growth, but fast growth and recruitment of multiple cohorts were possible throughout much (7–10 months) of the year
and especially during the warm, wet southwest monsoon. The diet, as revealed by stomach-content analysis, consisted mainly
of detritus and macrophytes, and was broadly consistent among habitats despite considerable variation in the composition and
cover of aquatic plants. Apple snail annual production was >10 times greater than production estimates for other benthic macroinvertebrates
in Hong Kong (range 0.004–15 g AFDM m−2 year−1, n = 29). Furthermore, annual production estimates for three apple snail populations (i.e. >230 g AFDM m−2 year−1) were greater than published estimates for any other freshwater snails (range 0.002–194 g AFDM m−2 year−1, n = 33), regardless of climatic regime or habitat type. High production by P. canaliculata in Hong Kong was attributable to the topical climate (annual mean ~24°C), permitting rapid growth and repeated reproduction,
together with dietary flexibility including an ability to consume a range of macrophytes. If invasive P. canaliculata can monopolize food resources, its high productivity indicates potential for competition with other macroinvertebrate primary
consumers. Manipulative experiments will be needed to quantify these impacts on biodiversity and ecosystem function in wetlands,
combined with management strategies to prevent further range extension by P. canaliculata. 相似文献
11.
Since the late 1990s, the Pacific oyster (Crassostrea gigas) has spread into the East Frisian Wadden Sea (Germany). This invasion provided an opportunity to study the population dynamics
and the patterns of spread during the initial bioinvasion process. With its source area in The Netherlands, the bioinvasion
continues in an eastward direction, as documented by a gradient of high abundances in the west and low abundances in the east
during the first study year. One year later, abundances of the Pacific oyster were more heterogenic and differed between adjacent
tidal basins. The increase in population sizes at all study sites was very high, reaching levels similar to native occurrence
populations. The growth constant (K) varied between 0.300 and 0.990 year−1. The mussel bed with the highest densities had a mean abundance of >300 ind. m−2, and a maximum of 1,460 ind. m−2. Furthermore, the bioinvasion was facilitated by a low mortality (Z) found for populations between 0.5 and 1.5 years old (Z = 0.03–0.13 year−1). At present, Pacific oysters are well established at several locations in the East Frisian Wadden Sea and may become with
these reproductive potential self-sustaining populations. 相似文献
12.
Macrophyte beds have been shown to influence organic matter retention and nutrient processing in streams. Less is known about
the extent to which plant beds contribute to abundance, biomass, and diversity of macroinvertebrate assemblages in low-order
streams. We measured aquatic invertebrate abundance, biomass, and diversity associated with plant beds and sand/gravel patches
in a low-gradient second-order stream in the Central Sand Plains of Wisconsin, USA from March to October. Invertebrate abundance
and biomass were higher on average in plant beds (2,552 m−2 and 1,575 mg m−2) than in sand/gravel patches (893 m−2 and 486 mg m−2). Although sand/gravel habitat was over three times more abundant than plant beds in the study reach, plant beds and sand/gravel
patches contributed similarly to invertebrate abundance and biomass at the whole-reach scale. The abundance and biomass of
invertebrates associated with plant beds decreased from spring to autumn. Non-insect invertebrates in the plant beds increased
in relative abundance as the year progressed. Shannon–Weiner diversity and taxa richness of invertebrates were higher in the
plant beds than in the sand/gravel habitat. Our results suggest that plant beds can represent hot spots for invertebrate abundance
and production in low-gradient streams, and have implications for stream management and restoration in these types of ecosystems.
Handling editor: S. I. Dodson 相似文献
13.
Nototheniid and myctophid fish are primary prey for marine piscivores, yet little is known about their nutritional value.
In this study, we characterized the proximate composition [PC: water, fat (neutral lipids), crude protein (CP) and ash] and
energy density (ED; kJ g−1) of fifteen fish species from McMurdo Sound and the Ross Sea, Antarctica. We assayed the entire fish for all species except
for the large Antarctic toothfish, Dissostichus mawsoni (muscle tissue only). On a wet mass basis (WM), fish were variable in composition: moisture content ranged from 64.9 to 87.3%
WM, fat from 0.5 to 17.4% WM, CP from 7.7 to 16.7% WM, ash from 11.2 to 21.0% FFDM (fat-free dry mass), and ED from 2.9 to
10.3 kJ g−1. Myctophids and pelagic nototheniids such as Pleuragramma antarcticum and D. mawsoni were high in fat content (7–17% WM), while a bathylagid and benthic nototheniids including most Trematomus spp. and Lepidonotothen squamifrons were low in fat (0.5–4% WM). The epibenthic Trematomus species (T. eulepidotus and T. lepidorhinus) were intermediate. Energy density tracked fat content, with highest values in myctophids and pelagic nototheniids. The variation
in nutrient and energy density confirms that prey composition must be taken into account when modelling energy and nutrient
fluxes within the Antarctic ecosystem. Further analyses of prey collected over a number of different locations and seasons
are needed in order to determine how the nutritional value of certain species might affect annual or decadal variation in
reproductive success or population size of top predators. 相似文献
14.
Arthropod communities in a Japanese cedar (Cryptomeria japonica D. Don) plantation: Abundance,biomass and some properties 总被引:3,自引:0,他引:3
Naoki Hijii 《Ecological Research》1989,4(3):243-260
Arboreal arthropod communities were censused by insecticidal knockdown in a plantation of Japanese cedar,Cryptomeria japonica, in central Japan from April 1983 to February 1985 at intervals of two months. All arthropods sampled were allocated to higher
taxonomic groups or guilds and the composition of the communities was analyzed with respect to abundance, biomass and their
seasonal trends. The total densities fluctuated seasonally from 200 to 3500 m−2; corresponding biomass values ranged from 7 to 600 mg fresh weight m−2. Maximum density and biomass generally occurred in summer and were minimum in winter. The consistently dominant guild in
terms of abundance were the detritivores, mostly comprising Collembola and oribatid mites, accounting for 36–93% of all arthropods;
phytophages, predators and detritivores were major guilds in terms of biomass, showing average proportions of 27%, 23% and
20%, respectively.
Biomass ratios of predators to prey were generally high in some canopy communities, suggesting the importance of predation
pressure in regulating the population levels of arthropods in forests. Average individual size of predators was approximately
proportional to that of prey, irrespective of tree locality. Soil arthropod communities maintained densities approximately
102–103 times as large as the corresponding canopy communities throughout the year. The seasonal variations in abundance were much
greater in canopy than in soil communities. 相似文献
15.
Sarah E. Jamieson H. Grant Gilchrist Flemming R. Merkel Antony W. Diamond Knud Falk 《Polar Biology》2006,29(7):585-594
Endogenous reserves influence both survival and reproduction of many waterfowl species, but little is known about reserve levels of most species during the nonbreeding season, particularly those wintering at high latitudes. We investigated whether age, sex, and season were related to carcass composition of northern common eiders (Somateria mollissima borealis) wintering in southwest Greenland during 1999–2002. Adults carried more lipid and protein than juveniles during all winters. Among both age classes, males and females had similar fat levels but males carried slightly more protein. There was no dramatic seasonal variation in lipid or protein content. This suggests that during the period of this study, these eiders did not experience large-scale nutritional shortfalls. As predicted, Greenlandic eiders carried more lipid reserves than eider populations wintering in more temperate environments. Contrary to prediction, there was little relation between reserve levels and photoperiod, ambient temperature, or hunting disturbance intensity. Our results suggest that both sexes are equally capable of dealing with nutritional deficits, and that juvenile birds are more prone to nutritional stress as evidenced by their consistently poorer body condition. 相似文献
16.
Responses of sawgrass and spikerush to variation in hydrologic drivers and salinity in Southern Everglades marshes 总被引:3,自引:3,他引:0
Daniel L. Childers David Iwaniec Damon Rondeau Gustavo Rubio Emilie Verdon Christopher J. Madden 《Hydrobiologia》2006,569(1):273-292
Aboveground net primary production (ANPP) by the dominant macrophyte and plant community composition are related to the changing
hydrologic environment and to salinity in the southern Everglades, FL, USA. We present a new non-destructive ANPP technique
that is applicable to any continuously growing herbaceous system. Data from 16 sites, collected from 1998 to 2004, were used
to investigate how hydrology and salinity controlled sawgrass (Cladium jamaicense Crantz.) ANPP. Sawgrass live biomass showed little seasonal variation and annual means ranged from 89 to 639 gdw m−2. Mortality rates were 20–35% of live biomass per 2 month sampling interval, for biomass turnover rates of 1.3–2.5 per year.
Production by C. jamaicense was manifest primarily as biomass turnover, not as biomass accumulation. Rates typically ranged from 300 to 750 gdw m−2 year−1, but exceeded 1000 gdw m−2 year−1 at one site and were as high as 750 gdw m−2 year−1 at estuarine ecotone sites. Production was negatively related to mean annual water depth, hydroperiod, and to a variable
combining the two (depth-days). As water depths and hydroperiods increased in our southern Everglades study area, sawgrass
ANPP declined. Because a primary restoration goal is to increase water depths and hydroperiods for some regions of the Everglades,
we investigated how the plant community responded to this decline in sawgrass ANPP. Spikerush (Eleocharis sp.) was the next most prominent component of this community at our sites, and 39% of the variability in sawgrass ANPP was
explained by a negative relationship with mean annual water depth, hydroperiod, and Eleocharis sp. density the following year. Sawgrass ANPP at estuarine ecotone sites responded negatively to salinity, and rates of production
were slow to recover after high salinity years. Our results suggest that ecologists, managers, and the public should not necessarily
interpret a decline in sawgrass that may result from hydrologic restoration as a negative phenomenon. 相似文献
17.
The phytoplankton and sea ice algal communities at the end of winter in McMurdo Sound were dominated by Fragilariopsis sublineata, with Thalassiosira antarctica, Melosira adele, Pinnularia quadreata, Entomoneis kjellmannii and heterotrophic dinoflagellates also present. Sea ice algal biomass at the end of winter was very low, only 0.050 ± 0.019 mg chla m−2 in 2007 and 0.234 ± 0.036 mg chla m−2 in 2008, but this increased to 0.377 ± 0.078 mg chla m−2 by early October in 2007 and to 1.07 ± 0.192 by late September in 2008. Under ice phytoplankton biomass remained consistently
below 0.1 μg chla l−1 throughout the measuring period in both years. The photosynthetic parameters Fv/Fm, rETRmax and α document microalgal communities
that are mostly healthy and well adapted to their low light under ice environment. Our results also suggest that species such
as Fragilariopsis sublineata are well adapted to deal with low winter light levels but are unlikely to survive an increase in irradiance, whereas other
taxa, such as Thalassiosira antarctica, will do better in a higher light environment. 相似文献
18.
Marzia Bo Marco Bertolino Giorgio Bavestrello Simonepietro Canese Michela Giusti Michela Angiolillo Maurizio Pansini Marco Taviani 《Hydrobiologia》2012,687(1):163-177
The Mediterranean spongofauna is relatively well-known for habitats shallower than 100 m, but, differently from oceanic basins,
information upon diversity and functional role of sponge grounds inhabiting deep environments is much more fragmentary. Aims
of this article are to characterize through ROV image analysis the population structure of the sponge assemblages found in
two deep habitats of the Mediterranean Sea and to test their structuring role, mainly focusing on the demosponges Pachastrella monilifera Schmidt, 1868 and Poecillastra compressa (Bowerbank, 1866). In both study sites, the two target sponge species constitute a mixed assemblage. In the Amendolara Bank
(Ionian Sea), where P. compressa is the most abundant species, sponges extend on a peculiar tabular bedrock between 120 and 180 m depth with an average total
abundance of 7.3 ± 1.1 specimens m−2 (approximately 230 gWW m−2 of biomass). In contrast, the deeper assemblage of Bari Canyon (average total abundance 10.0 ± 0.7 specimens m−2, approximately 315 gWW m−2 of biomass), located in the southwestern Adriatic Sea between 380 and 500 m depth, is dominated by P. monilifera mixed with living colonies of the scleractinian Madrepora oculata Linnaeus, 1758, the latter showing a total biomass comparable to that of sponges (386 gWW m−2). Due to their erect growth habit, these sponges contribute to create complex three-dimensional habitats in otherwise homogenous
environments exposed to high sedimentation rates and attract numerous species of mobile invertebrates (mainly echinoderms)
and fish. Sponges themselves may represent a secondary substrate for a specialized associated fauna, such zoanthids. As demonstrated
in oceanic environments sponge beds support also in the Mediterranean Sea locally rich biodiversity levels. Sponges emerge
also as important elements of benthic–pelagic coupling in these deep habitats. In fact, while exploiting the suspended organic
matter, about 20% of the Bari sponge assemblage is also severely affected by cidarid sea urchin grazing, responsible to cause
visible damages to the sponge tissues (an average of 12.1 ± 1.8 gWW of individual biomass removed by grazing). Hence, in deep-sea
ecosystems, not only the coral habitats, but also the grounds of massive sponges represent important biodiversity reservoirs
and contribute to the trophic recycling of organic matter. 相似文献
19.
The mesozooplankton of the northern White Sea and Mezen Bay was investigated at nine stations in July 2008 using a Juday net
(168 μm mesh size). A total of 39 taxa (species and higher taxa) were found in the samples. Average abundance, biomass, and
diversity (Shannon index) were (±SE) 120,793 ± 70,439 ind. m−2, 443 ± 216 mg DW m−2, and 1.41 ± 0.11, respectively. Copepods were most numerous. Overall, herbivores dominated primarily Cirripedia nauplii and
Pseudocalanus minutus. Significant correlations were observed among mean temperature, salinity, and mean mesozooplankton abundance and biomass.
Our data suggest that salinity and intensive local currents could be the main factors responsible for the distribution of
mesozooplankton in the northern White Sea. The average mesozooplankton biomass was higher than in previous studies, indicating
a possible climatic impact on the mesozooplankton community. 相似文献
20.
McCormick Paul V. Shuford III Robert B. E. Backus John G. Kennedy William C. 《Hydrobiologia》1997,362(1-3):185-210
We sampled periphyton in dominant habitats at oligotrophic and eutrophic sites in the northern Everglades during the wet and
the dryseasons to determine the effects of nutrient enrichment on periphytonbiomass, taxonomic composition, productivity,
and phosphorus storage. Arealbiomass was high (100–1600 g ash-free dry mass [AFDM]m−2) in oligotrophic sloughs and in stands of the emergentmacrophyte Eleocharis cellulosa, but was low in adjacent stands of
sawgrass,Cladium jamaicense (7–52 g AFDM m−2). Epipelon biomasswas high throughout the year at oligotrophic sites whereas epiphyton andmetaphyton biomass varied seasonally
and peaked during the wet season.Periphyton biomass was low (3–68 g AFDM m−2) and limitedto epiphyton and metaphyton in open-water habitats at eutrophic sites andwas undetectable in cattail stands (Typha
domingensis) that covered morethan 90% of the marsh in these areas. Oligotrophic periphytonassemblages exhibited strong seasonal
shifts in species composition and weredominated by cyanobacteria (e.g., Chroococcus turgidus, Scytonema hofmannii)during the
wet season and diatoms (e.g. Amphora lineolata, Mastogloiasmithii) during the dry season. Eutrophic assemblages were dominated
byCyanobacteria (e.g., Oscillatoria princeps) and green algae (e.g., Spirogyraspp.) and exhibited comparatively little seasonality.
Biomass-specific grossprimary productivity (GPP) of periphyton assemblages in eutrophic openwaters was higher than for comparable
slough assemblages, but areal GPP wassimilar in these eutrophic (0.9–9.1 g C m−2d−1) and oligotrophic (1.75–11.49 g C m−2d−1) habitats. On a habitat-weighted basis, areal periphytonGPP was 6- to 30-fold lower in eutrophic areas of the marsh due to
extensiveTypha stands that were devoid of periphyton. Periphyton at eutrophic siteshad higher P content and uptake rates than
the oligotrophic assemblage, butstored only 5% as much P because of the lower areal biomass.Eutrophication in the Everglades
has resulted in a decrease in periphytonbiomass and its contribution to marsh primary productivity. These changesmay have
important implications for efforts to manage this wetland in asustainable manner.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献