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1.
Distribution and diversity of sipunculan fauna in high Arctic fjords (west Svalbard) 总被引:1,自引:0,他引:1
Sipuncula is a relatively species poor and generally rarely investigated phylum; nonetheless, it may play a considerable role
in the ecosystem. During this study sipunculan species distribution patterns in four fjords of west Spitsbergen (Kongsfjorden,
Hornsund, Isfjorden and van Mijenfjorden) were examined. Material was collected during ten cruises undertaken from 1997 to
2006. A total of 381 samples were taken at 132 stations located in the four fjords and, a total number of 920 sipunculans
specimens were found in 114 of those samples. The highest sipunculan species richness was observed in Hornsund (six species),
followed by Kongsfjorden and Isfjorden (five species in each fjord). Sipunculan fauna in all fjords was strongly dominated
by Golfingia vulgaris (80% of all sipunculan individuals in Kongsfjorden), and Golfingia margaritacea (84% in van Mijenfjorden and 40% in Hornsund) or Nephasoma diaphanes (54% in Isfjorden). Locally, sipunculans were found in high densities (max. 62 ind. 0.1 m−2 and up to 11% of macrobenthic densities) and biomass (max. 110.87 g 0.1 m−2 and up to 80% of total fauna biomass). At such sites, sipunculans may play an important role in bioturbation of sediments
and as a food source for higher trophic levels. Sipunculans did not occur within close proximity of the glacier where they
might be eliminated due to high sedimentation rate and low amounts of organic matter. Because of their importance in benthic
systems, a need to include sipunculans in routine macrobenthic surveys is emphasized. 相似文献
2.
Jana Woelfel Rhena Schumann Florian Peine Anita Flohr Aleksandra Kruss Jaroslaw Tegowski Philippe Blondel Christian Wiencke Ulf Karsten 《Polar Biology》2010,33(9):1239-1253
During summer 2007, Arctic microphytobenthic potential primary production was measured at several stations around the coastline
of Kongsfjorden (Svalbard, Norway) at ≤5 m water depth and at two stations at five different water depths (5, 10, 15, 20,
30 m). Oxygen planar optode sensor spots were used ex situ to determine oxygen exchange in the overlying water of intact sediment
cores under controlled light (ca. 100 μmol photons m−2 s−1) and temperature (2–4°C) conditions. Patches of microalgae (mainly diatoms) covering sandy sediments at water depths down
to 30 m showed high biomass of up to 317 mg chl a m−2. In spite of increasing water depth, no significant trend in “photoautotrophic active biomass” (chl a, ratio living/dead cells, cell sizes) and, thus, in primary production was measured at both stations. All sites from ≤5 to
30 m water depth exhibited variable rates of net production from −19 to +40 mg O2 m−2 h−1 (−168 to +360 mg C m−2 day−1) and gross production of about 2–62 mg O2 m−2 h−1 (17–554 mg C m−2 day−1), which is comparable to other polar as well as temperate regions. No relation between photoautotrophic biomass and gross/net
production values was found. Microphytobenthos demonstrated significant rates of primary production that is comparable to
pelagic production of Kongsfjorden and, hence, emphasised the importance as C source for the zoobenthos. 相似文献
3.
Motomi Genkai-Kato Miyuki Onishi Hideyuki Doi Kentaro Nozaki Kenji Yoshino Hitoshi Miyasaka Koji Omori 《Ecological Research》2008,23(6):1025-1032
We investigated the photosynthesis–light intensity (P–I) relationships of phytoplankton collected from a sublittoral sand
bank in the Seto Inland Sea, Japan, under different temperature conditions. In spite of low chlorophyll a concentration (<3 mg m−3), phytoplankton had considerably high photosynthetic potential (>10 mg C (mg chl a)−1 h−1) in the study area. Based on the P–I relationships, we conducted numerical simulation of areal primary production using published
data on water temperature, chlorophyll a concentration, and irradiance. The areal primary production ranged between 159 and 187 g C m−2 year−1. This production was within the range of typical values reported previously in deeper areas of the Seto Inland Sea. The productivity
in the sand bank area was discussed in relation to water current, allochthonous resource input, and fisheries. 相似文献
4.
The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard,
during six consecutive field campaigns between March and December 2006. Total ciliate and dinoflagellate abundance mirrored
the seasonal progression of phytoplankton, peaking with 5.8 × 104 cells l−1 in April at an average chlorophyll a concentration of 10 μg l−1. Dinoflagellates were more abundant than ciliates, dominated by small athecates. Among ciliates, aloricate oligotrichs dominated
the assemblage. A large fraction (>60%) of ciliates and dinoflagellates contained chloroplasts in spring and summer. The biomass
of the purely heterotrophic fraction of the ciliate and dinoflagellate community (protozooplankton) was with 14 μg C l−1 highest in conjunction with the phytoplankton spring bloom in April. Growth experiments revealed similar specific growth
rates for heterotrophic ciliates and dinoflagellates (<0–0.8 d−1). Food availability may have controlled the protozooplankton assemblage in winter, while copepods may have exerted a strong
control during the post-bloom period. Calculations of the potential grazing rates of the protozooplankton indicated its ability
to control or heavily impact the phytoplankton stocks at most times. The results show that ciliates and dinoflagellates were
an important component of the pelagic food web in Kongsfjorden and need to be taken into account when discussing the fate
of phytoplankton and biogeochemical cycling in Arctic marine ecosystems. 相似文献
5.
6.
Christine E. Cooper Philip C. Withers 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(6):857-868
Quolls (Dasyurus) are medium-sized carnivorous dasyurid marsupials. Tiger (3,840 g) and eastern quolls (780 g) are mesic zone species, northern
quolls (516 g) are tropical zone, and chuditch (1,385 g) were once widespread through the Australian arid zone. We found that
standard physiological variables of these quolls are consistent with allometric expectations for marsupials. Nevertheless,
inter-specific patterns amongst the quolls are consistent with their different environments. The lower T
b of northern quolls (34°C) may provide scope for adaptive hyperthermia in the tropics, and they use torpor for energy/water
conservation, whereas the larger mesic species (eastern and tiger quolls) do not appear to. Thermolability varied from little
in eastern (0.035°C °C−1) and tiger quolls (0.051°C oC−1) to substantial in northern quolls (0.100°C oC−1) and chuditch (0.146°C oC−1), reflecting body mass and environment. Basal metabolic rate was higher for eastern quolls (0.662 ± 0.033 ml O2 g−1 h−1), presumably reflecting their naturally cool environment. Respiratory ventilation closely matched metabolic demand, except
at high ambient temperatures where quolls hyperventilated to facilitate evaporative heat loss; tiger and eastern quolls also
salivated. A higher evaporative water loss for eastern quolls (1.43 ± 0.212 mg H2O g−1 h−1) presumably reflects their more mesic distribution. The point of relative water economy was low for tiger (−1.3°C), eastern
(−12.5°C) and northern (+3.3) quolls, and highest for the chuditch (+22.6°C). We suggest that these differences in water economy
reflect lower expired air temperatures and hence lower respiratory evaporative water loss for the arid-zone chuditch relative
to tropical and mesic quolls. 相似文献
7.
Petroleum-related activities in Arctic waters are rapidly increasing parallel to the ongoing thinning of the Arctic sea ice.
As part of a series of studies on petroleum-induced stress in polar cod Boreogadus saida, we tested the effects of acute (~60 min) and chronic (4 weeks) exposure to the water soluble fraction (WSF) of petroleum
on whole body metabolism inferred from measurements of oxygen consumption rates. The exposure of polar cod to WSF leads to
a statistically significant depression in routine metabolism in the order Control (0.260 mg O2 g fish−1 h−1; N = 6) > Chronic (0.191 mg O2 g fish−1 h−1; N = 6) > Acute (0.110 mg O2 g fish−1 h−1; N = 2), decoupling of routine metabolism and body mass but possibly also to a partial metabolic compensation after 4 weeks
of exposure. The results are reviewed in context with similar studies on Antarctic and non-polar fishes. 相似文献
8.
Population structure, growth and body composition (wet-, dry-, ash weight and total lipid) of the Arctic pelagic amphipod Themisto libellula were studied in four fjords on West Spitsbergen, Svalbard, from July to December 2000 and in April 2002. In one of the fjords, Kongsfjorden, growth of T. libellula was calculated as the change in mean length of the 0+ cohort from July to December. The young were released from the brood pouches in early spring (March–April). Summer growth was 3.5 mm month−1, whereas growth during the autumn was only 0.6 mm month−1. The size frequency distributions indicated a 2–2.5 year life-span. The size structure of the population in Hornsund, the southernmost fjord on Spitsbergen, indicated a delayed time of spawning. The storage of lipids in T. libellula occurred during late summer and towards the winter, when the food items contain the maximum amount of stored lipids. 相似文献
9.
Spring bloom dynamics in Kongsfjorden,Svalbard: nutrients,phytoplankton, protozoans and primary production 总被引:1,自引:0,他引:1
The marine ecosystem in Kongsfjorden (79°N), a glacial fjord in Svalbard, is to a large extent well known with regard to hydrography,
mesozooplankton and higher trophic levels. Research on primary production and lower trophic levels is still scare and especially
investigations from winter and spring periods. The spring bloom dynamics in Kongsfjorden were investigated in 2002. The development
in nutrient conditions, phytoplankton, protozoans and primary production were followed from 15 April until 22 May. The winter/spring
in 2002 was categorized as a cold year with sea ice cover and water masses dominated by local winter-cooled water. The spring
bloom started around 18 April and lasted until the middle of May. The bloom probably peaked in late April, but break-up of
sea ice made it impossible to sample frequently in this period. Diatoms dominated the phytoplankton assemblage. We estimated
the total primary production during the spring bloom in 2002 to range 27–35 g C m−2. There was a mismatch situation between the mesozooplankton and the phytoplankton spring bloom in 2002. 相似文献
10.
Landfast ice algal communities were studied in the strongly riverine-influenced northernmost part of the Baltic Sea, the Bothnian
Bay, during the winter-spring transition of 2004. The under-ice river plume, detected by its low salinity and elevated nutrient
concentrations, was observed only at the station closest to the river mouth. The bottommost ice layer at this station was
formed from the plume water (brine volume 0.71%). This was reflected by the low flagellate-dominated (93%) algal biomass in
the bottom layer, which was one-fifth of the diatom-dominated (74%) surface-layer biomass of 88 μg C l−1. Our results indicate that habitable space plays a controlling role for ice algae in the Bothnian Bay fast ice. Similarly
to the water column in the Bothnian Bay, average dissolved inorganic N:P-ratios in the ice were high, varying between 12 and
265. The integrated chlorophyll a (0.1–2.2 mg m−2) and algal biomass in the ice (1–31 mg C m−2) correlated significantly (Spearman ρ = 0.79), with the highest values being measured close to the river mouth in March and during the melt season in April. Flagellates
<20 μm generally dominated in both the ice and water columns in February–March. In April the main ice-algal biomass was composed
of Melosira arctica and unidentified pennate diatoms, while in the water column Achnanthes taeniata, Scrippsiella hangoei and flagellates dominated. The photosynthetic efficiency (0.003–0.013 (μg C [μg chl a
−1] h−1)(μE m−2s−1)−1) and maximum capacity (0.18–1.11 μg C [μg chl a
−1] h−1) could not always be linked to the algal composition, but in the case of a clear diatom dominance, pennate species showed
to be more dark-adapted than centric diatoms. 相似文献
11.
Luz Allende Guillermo Tell Horacio Zagarese Ana Torremorell Gonzalo Pérez José Bustingorry Roberto Escaray Irina Izaguirre 《Hydrobiologia》2009,624(1):45-60
Shallow lakes often alternate between two possible states: one clear with submerged macrophytes, and another one turbid, dominated
by phytoplankton. A third type of shallow lakes, the inorganic turbid, result from high contents of suspended inorganic material,
and is characterized by low phytoplankton biomass and macrophytes absence. In our survey, the structure and photosynthetic
properties (based on 14C method) of phytoplankton were related to environmental conditions in these three types of lakes in the Pampa Plain. The
underwater light climate was characterized. Clear-vegetated lakes were more transparent (K
d 4.5–7.7 m−1), had high DOC concentrations (>45 mg l−1), low phytoplankton Chl a (1.6–2.7 μg l−1) dominated by nanoflagellates. Phytoplankton productivity and photosynthetic efficiency (α ~ 0.03 mgC mgChla
−1 h−1 W−1 m2) were relatively low. Inorganic-turbid lakes showed highest K
d values (59.8–61.4 m−1), lowest phytoplankton densities (dominated by Bacillariophyta), and Chl a ranged from 14.6 to 18.3 μg l−1. Phytoplankton-turbid lakes showed, in general, high K
d (4.9–58.5 m−1) due to their high phytoplankton abundances. These lakes exhibited the highest Chl a values (14.2–125.7 μg l−1), and the highest productivities and efficiencies (maximum 0.56 mgC mgChla
−1 h−1 W−1 m2). Autotrophic picoplankton abundance, dominated by ficocianine-rich picocyanobacteria, differed among the shallow lakes independently
of their type (0.086 × 105–41.7 × 105 cells ml−1). This article provides a complete characterization of phytoplankton structure (all size fractions), and primary production
of the three types of lakes from the Pampa Plain, one of the richest areas in shallow lakes from South America.
Handling editor: J. Padisak 相似文献
12.
Phytoplankton productivity and its response to higher light levels in the Canada Basin 总被引:1,自引:0,他引:1
Phytoplankton productivity in the Canada Basin was measured in the late summer season, from mid-September to mid-October 2009,
using a 13C–15N dual tracer technique. To understand potential production changes associated with sea ice melting in the Arctic Ocean, we
examined the effects of light enhancement and nitrate enrichment on the carbon productivity of phytoplankton from the chlorophyll
a maximum layer. The daily carbon productivity in the Canada Basin in 2009 was very low, with a mean of 4.1 mg C m−2 (SD = 3.6 mg C m−2), compared with those reported in previous studies in the region. Among several explanations, the most plausible reason for
the large difference in carbon productivity between this and the previous studies was strong seasonal variation in biomass
and photosynthetic rate of the phytoplankton in the study region. Based on our results from light enhancement and nitrate
enrichment experiments, we found that carbon productivity of phytoplankton in the chlorophyll a maximum layer could be stimulated by increased light condition rather than nitrate addition. Thus, potentially increasing
light availability from current and ongoing decreases in the sea ice cover could increase the carbon production of the phytoplankton
in the chlorophyll a maximum layer and produce a well-developed maximum layer at a deeper depth in the Canada Basin. 相似文献
13.
Sempere F Martínez-Soria V Palau J Penya-Roja JM San-Valero P Gabaldón C 《Bioprocess and biosystems engineering》2011,34(7):859-867
The removal of styrene-polluted air emissions by biotrickling filtration was performed to evaluate the influence of using
nitrate and urea as a nitrogen source in the nutrient solution supplied to two bioreactors run in parallel under the same
operational conditions for 3 months. The use of urea resulted in less biomass content along the packed bed and better performance
of the process, with a maximum elimination capacity (EC) of 57.6 g C m−3 h−1 (removal efficiency (RE) of 88.3% and empty bed residence time (EBRT) of 60 s), which was around 54% higher than when using
nitrate. EBRTs of 60, 30 and 15 s were evaluated with a urea-based nutrient supply. By decreasing the EBRT from 60 to 30 s
the styrene concentration that could be treated with REs above 80% was almost the half, from 1,100 to 600 mg C m−3, resulting in ECs of 52.8 g C m−3 h−1. Working at 15 s was not possible to obtain REs higher than 40% with a maximum EC of 28.5 g C m−3 h−1. 相似文献
14.
The principal environmental factors influencing the seasonal dynamics of phytoplankton were examined from September 1997 to
July 1998 in three stations along a 26-km stretch of the lowland course of River Adige (northeast Italy). Nutrient concentrations
did not appear to be limiting for the phytoplankton growth. Annual minimum concentrations of reactive and total phosphorus,
and dissolved inorganic nitrogen were 22 μg P l−1, 63 μg P l−1 and 0.9 mg N l−1, respectively. The most critical forcing factors were physical variables, mainly water discharge and other variables related
to hydrology, i.e. suspended solids and turbidity, which acted negatively and synchronously by diluting phytoplankton cells
and decreasing light availability. Higher algal biomass was recorded in early spring, in conditions of lower flow velocity
and increasing water temperature. In late spring and summer, higher water discharge caused a decrease in phytoplankton biomass.
Conversely, low algal biomass in late autumn and winter, during low discharge, was mainly related to low water temperatures
and shorter photoperiod. Physical constraints had a significant and measurable effect not only on the development of total
biomass, but also on the temporal dynamics of the phytoplankton community. Abiotic and biotic variables showed a comparable
temporal development in the three sampling stations. The small number of instances of spatial differences in phytoplankton
abundance during the period of lower flow velocity were related to the increasing importance of biological processes and accumulation
of phytoplankton biomass. 相似文献
15.
Xiuyun Cao Chunlei Song Yiyong Zhou Alena Štrojsová Petr Znachor Eliška Zapomělová Jaroslav Vrba 《Limnology》2009,10(2):95-104
Extracellular phosphatases are an important part of the phosphorus cycle in aquatic environments. Phosphatase activity (PA)
in plankton was studied in seven subtropical shallow lakes of different exploitation management and trophic status in the
urban area of Wuhan City. Bulk PA was rather high (range 1.1–11 μmol l−1 h−1), although concentrations of soluble reactive phosphorus (SRP) were also high (range 27 μg P l−1 to ~1.5 mg P l−1) in all lakes. Cell-associated extracellular PA in phytoplankton was detected using the fluorescence-labelled enzyme activity
technique. Phytoplankton species partly contributed to the bulk PA. We found explicit differences in the presence of cell-associated
phosphatase within the main phytoplankton groups; species belonging to Chlorophyta and Dinophyta were regularly phosphatase-positive,
while Cyanophyta and Bacillariophyceae were phosphatase-negative in all but one case. Furthermore, there is a certain potential
of extracellular phosphatases produced by heterotrophic nanoflagellates in most of the lakes. This new finding compromises
the ‘traditional’ interpretation of bulk phosphatase data as being due to overall phytoplankton or bacterial P regeneration. 相似文献
16.
Copepods are considered to be the main component of the Arctic marine zooplankton. We examined the copepod distribution and
diversity off Franz Josef Land (northern Barents Sea) in August 2006 and 2007. A total of 18 and 14 copepod taxa were identified
from the sampling layers (100–0 m or bottom–0 m) in 2006 and in 2007, respectively. There were no significant differences
in the total copepod abundance between the years (means ± SE: 118,503 ± 24,115 individuals m−2 in 2006 vs. 113,932 ± 28,564 individuals m−2 in 2007). However, the copepod biomass in 2006 (4,518 ± 1,091 mg C m−2) exceeded clearly the value in 2007 (1,253 ± 217 mg C m−2). The copepod community showed low species richness and diversity in both years (Simpson index D: 0.34 and 0.38, respectively).
Biomass of the large and small copepod species strongly decreased from 2006 to 2007. The total abundance of copepods was negatively
correlated with water temperature in 2006 and positively correlated with salinity in 2007. The patchiness in copepod distribution
was associated with local hydrography and temperature conditions. 相似文献
17.
Juan Fuentes F. B. Eddy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(6):438-443
Drinking in Atlantic salmon (Salmo salar) juveniles was investigated in fresh water and following transfer to sea water. There was a significant effect of fish size
on drinking, and smolts (20–30 g) imbibed about ten times less water than alevins of 0.2–0.3 g. Freshwater smolts drank at
a rate of 0.15 ± 0.03 ml · kg−1 · h−1 and administration of doses of 10 or 20 mg · kg−1 of papaverine (stimulator of the renin- angiotensin system RAS) or [Asn1, Val5]-Angiotensin II (0.4 μmol · kg−1) resulted in significant increases in drinking, while administration of the angiotensin converting enzyme inhibitor, enalapril
(50 mg · kg−1) had no effect on drinking. Transfer of Atlantic salmon smolts to 1/3, 2/3 and full strength sea water resulted in significant
increases in drinking to 1.06 ± 0.12, 1.24 ± 0.0.16 and 3.89 ± 0.28 ml · kg−1 · h−1, respectively. In sea water, stimulation of the endogenous RAS by administration of papaverine (20 mg · kg−1) resulted in a 20% increase in drinking, while administration of enalapril to doses of 50 and 200 mg · kg−1 lowered drinking to 1.99 ± 0.48 and 0.32 ± 0.06 ml · kg−1 · h−1, respectively. All treatments were without effect on blood plasma levels of Na+ and Cl− in fresh water, while in sea water smolts both stimulation and inhibition of drinking resulted in hemoconcentration of Na+ and Cl−. The role of the renin angiotensin system in control of drinking and hydromineral balance in Atlantic salmon is discussed.
Accepted: 27 February 1997 相似文献
18.
The pulsing of river discharge affects biodiversity and productivity of whole river–floodplain ecosystems, triggering the transport, storage and processing of carbon. In this study we investigate the short-term changes in water chemistry and net pelagic metabolism (NEP) in two floodplain lakes in response to a flood pulse. The two oxbow lakes investigated in the floodplain of the Mediterranean Ebro River (NE Spain) showed a clear temporal shift in their metabolic balance, controlled by the river discharge and associated changes in water physical and chemical characteristics. Water chemistry (turbidity, water organic matter, chlorophyll a and nutrients concentration) returned to pre-flood values after 4 days, highlighting the resilience of the ecosystem to flood pulses. Lake NEP was depressed before and during floods to a minimum of −34 mg O2 m−3 h−1, and increased after the flood pulse to a maximum of +463 mg O2 m−3 h−1. The phytoplankton assemblage showed before and after floods a replacement of autotrophic species (e.g. Chlorophyceans) by mixotrophic organisms (e.g. Cryptophyceans, Euglenoids). A linear mixed effects model identified abiotic factors, particularly temperature and river discharge, as significant predictors of the net aquatic metabolism and community respiration during flood conditions. Our results suggest that the role of the Ebro floodplain lakes as sources or sinks of C is complex and relative to the time scale investigated, depending strongly on the river discharge dynamics and the transport of limiting nutrients (phosphorus). 相似文献
19.
Phytoplankton biomass and primary production in the marginal ice zone of the northwestern Weddell Sea during austral summer 总被引:2,自引:0,他引:2
Myung Gil Park Sung Ryull Yang Sung-Ho Kang Kyung Ho Chung Jae Hyung Shim 《Polar Biology》1999,21(4):251-261
During the austral summer of 1995, distributions of phytoplankton biomass (as chlorophyll a), primary production, and nutrient concentrations along two north-south transects in the marginal ice zone of the northwestern
Weddell Sea were examined as part of the 8th Korean Antarctic Research Program. An extensive phytoplankton bloom, ranging
from 1.6 to 11.2 mg m−3 in surface chlorophyll a concentration, was encountered along the eastern transect and extended ca. 180 km north of the ice edge. The spatial extent
of the bloom was closely related to the density field induced by the input of meltwater from the retreating sea ice. However,
the extent (ca. 200 km) of the phytoplankton bloom along the western transect exceeded the meltwater-influenced zone (ca.
18 km). The extensive bloom along the western transect was more closely related to local hydrography than to the proximity
of the ice edge and the resulting meltwater-induced stability of the upper water column. In addition, the marginal ice zone
on the western transect was characterized by a deep, high phytoplankton biomass (up to 8 mg Chl a m−3) extending to 100-m depth, and the decreased nutrient concentration, which was probably caused by passive sinking from the
upper euphotic zone and in situ growth. Despite the low bloom intensity relative to the marginal ice zone in both of the transects,
mean primary productivity (2.6 g C m−2 day−1) in shelf waters corresponding to the northern side of the western transect was as high as in the marginal ice zone (2.1 g C m−2 day−1), and was 4.8 times greater than that in open waters, suggesting that shelf waters are as highly productive as the marginal
ice zone. A comparison between the historical productivity data and our data also shows that the most productive regions in
the Southern Ocean are shelf waters and the marginal ice zone, with emerging evidence of frontal regions as another major
productive site.
Accepted: 27 September 1998 相似文献
20.
A regional data set on water chemistry from 1995 was used to set critical values for the survival of brown trout in Norwegian
lakes (n = 790) in relation to pH, inorganic Al and acid neutralizing capacity (ANC). ANC was estimated both traditionally (ANCtrad) and modified by treating one-third of the dissolved organic matter as part of the strong acid anions (ANCmod). The threshold value to avoid fish damage (ANClimit) was compared with that found in a similar study from 1986. Brown trout populations were categorized as unaffected, damaged
or extinct on the basis of questionnaires. In 1995, threshold values to avoid fish damage on the basis of ANCtrad and ANCmod were 67 and 48 μeq l−1, respectively, compared with 20 and 8 μeq l−1, respectively, in 1986. The higher ANClimit found for the data from 1995 is probably caused by a lower pH and a higher inorganic Al concentration at a given ANC value
in 1995 than in the 1980s. ANClimit was highly related to organic carbon concentrations in the study lakes, being estimated at 33, 73 and >100 μeq l−1 for three different TOC categories (<2 mg C l−1, 2–5 mg C l−1 and >5 mg C l−1). These differences in ANClimit are due to lower pH and higher concentrations of inorganic Al in humic lakes than in clear water lakes at the same level
of ANC. It is suggested that the change in ANClimit for fish in acidified lakes is linked to increased concentrations of TOC in recent years. 相似文献