共查询到20条相似文献,搜索用时 140 毫秒
1.
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
2.
Checo Colón-Gaud Scot Peterson Matt R. Whiles Susan S. Kilham Karen R. Lips Cathy M. Pringle 《Hydrobiologia》2008,603(1):301-312
Allochthonous inputs of detritus represent an important energy source for streams in forested regions, but dynamics of these
materials are not well studied in neotropical headwater streams. As part of the tropical amphibian declines in streams (TADS)
project, we quantified benthic organic matter standing stocks and organic seston dynamics in four Panamanian headwater streams,
two with (pre-amphibian decline) and two without (post-decline) healthy amphibian assemblages. We also measured direct litterfall
and lateral litter inputs in two of these streams. Continuous litterfall and monthly benthic samples were collected for 1 year,
and seston was collected 1–3 times/month for 1 year at or near baseflow. Direct litterfall was similar between the two streams
examined, ranging from 934–1,137 g DM m−2 y−1. Lateral inputs were lower, ranging from 140–187 g DM m−1 y−1. Dead leaves (57–60%), wood (24–29%), and green leaves (8–9%) contributed most to inputs, and total inputs were generally
higher during the rainy season. Annual habitat-weighted benthic organic matter standing stocks ranged from 101–171 g AFDM
m−2 across the four study reaches, with ∼4 × higher values in pools compared to erosional habitats. Total benthic organic matter
(BOM) values did not change appreciably with season, but coarse particulate organic matter (CPOM, >1 mm) generally decreased
and very fine particulate organic matter (VFPOM, 1.6–250 μm) generally increased during the dry season. Average annual seston
concentrations ranged from 0.2–0.6 mg AFDM l−1 (fine seston, <754 μm >250 μm) and 2.0–4.7 mg AFDM l−1 (very fine, <250 μm >1.6 μm), with very fine particles composing 85–92% of total seston. Quality of fine seston particles
in the two reaches where tadpoles were present was significantly higher (lower C/N) than the two where tadpoles had been severely
reduced (P = 0.0028), suggesting that ongoing amphibian declines in this region are negatively influencing the quality of particles
exported from headwaters. Compared to forested streams in other regions, these systems receive relatively high amounts of
allochthonous litter inputs but have low in-stream storage.
Handling editor: J. Padisak 相似文献
3.
Respiration and annual fungal production associated with decomposing leaf litter in two streams 总被引:5,自引:0,他引:5
1. We compared fungal biomass, production and microbial respiration associated with decomposing leaves in one softwater stream (Payne Creek) and one hardwater stream (Lindsey Spring Branch). 2. Both streams received similar annual leaf litter fall (478–492 g m?2), but Lindsey Spring Branch had higher average monthly standing crop of leaf litter (69 ± 24 g m?2; mean ± SE) than Payne Creek (39 ± 9 g m?2). 3. Leaves sampled from Lindsey Spring Branch contained a higher mean concentration of fungal biomass (71 ± 11 mg g?1) than those from Payne Creek (54 ± 8 mg g?1). Maximum spore concentrations in the water of Lindsay Spring Branch were also higher than those in Payne Creek. These results agreed with litterbag studies of red maple (Acer rubrum) leaves, which decomposed faster (decay rate of 0.014 versus 0.004 day?1), exhibited higher maximum fungal biomass and had higher rates of fungal sporulation in Lindsey Spring Branch than in Payne Creek. 4. Rates of fungal production and respiration per g leaf were similar in the two streams, although rates of fungal production and respiration per square metre were higher in Lindsey Spring Branch than in Payne Creek because of the differences in leaf litter standing crop. 5. Annual fungal production was 16 ± 6 g m?2 (mean ± 95% CI) in Payne Creek and 46 ± 25 g m?2 in Lindsey Spring Branch. Measurements were taken through the autumn of 2 years to obtain an indication of inter‐year variability. Fungal production during October to January of the 2 years varied between 3 and 6 g m?2 in Payne Creek and 7–27 g m?2 in Lindsey Spring Branch. 6. Partial organic matter budgets constructed for both streams indicated that 3 ± 1% of leaf litter fall went into fungal production and 7 ± 2% was lost as respiration in Payne Creek. In Lindsey Spring Branch, fungal production accounted for 10 ± 5% of leaf litter fall and microbial respiration for 13 ± 9%. 相似文献
4.
Primary production of phytoplankton and secondary production of a daphnid and a chaoborid were studied in a small eutrophic
pond. The gross primary production of phytoplankton was 290 gC m−2 per 9 months during April–December. Regression analysis showed that the gross primary production was related to the incident
solar radiation and the chlorophylla concentration and not to either total phosphorus or total inorganic nitrogen concentration. The mean chlorophylla concentration (14.2 mg m−3), however, was about half the expected value upon phosphorus loading of this pond. The mean zooplankton biomass was 1.60
g dry weight m−2, of whichDaphnia rosea and cyclopoid copepods amounted to 0.69 g dry weight m−2 and 0.61 g dry weight m−2, respectively. The production ofD. rosea was high during May–July and October and the level for the whole 9 months was 22.6 g dry weight m−2.Chaoborus flavicans produced 10 complete and one incomplete cohorts per year. Two consecutive cohorts overlapped during the growing season. The
maximum density, the mean biomass, and the production were 19,100 m−2, 0.81 g dry weight m−2, and 11.7 g dry weight m−2yr−1, respectively. As no fish was present in this pond, the emerging biomass amounted to 69% of larval production. The production
ofC. flavicans larvae was high in comparison with zooplankton production during August–September, when the larvae possibly fed not only
on zooplankton but also algae. 相似文献
5.
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
6.
Periphyton biomass and ecological stoichiometry in streams within an urban to rural land-use gradient 总被引:2,自引:0,他引:2
This study examined the effects land use on biomass and ecological stoichiometry of periphyton in 36 streams in southeastern
New York State (USA). We quantified in-stream and land-use variables along a N–S land-use gradient at varying distances from
New York City (NYC). Streams draining different landscapes had fundamentally different physical, chemical, and biological
properties. Human population density significantly decreased (r = −0.739; P < 0.00001), while % agricultural land significantly increased (r = 0.347; P = 0.0379) with northing. Turbidity, temperature, conductivity, and dissolved Mg, Ca, SRP, pH, DOC, and Si significantly increased
in more urban locations, but NO3
− and NH4
+ did vary not significantly along the gradient. Periphyton biomass (as AFDM and Chl-a) in rural streams averaged one-third to one-fifth that measured in urban locations. Periphyton biomass in urban streams averaged
18.8 ± 6.0 g/m2 AFDM and 75.6 ± 28.5 mg/m2 Chl-a. Urban Chl-a levels ranging between 100 and 200 mg/m2, are comparable to quantities measured in polluted agricultural streams in other regions, but in our study area was not correlated
with % agricultural land. Periphyton nutrient content also varied widely; algal C varied >20-fold (0.06–1.7 μmol/mm2) while N and P content varied >6-fold among sites. Algal C, N, and P correlated negatively with distance from NYC, suggesting
that periphyton in urban streams may provide greater nutrition for benthic consumers. C:N ratios averaged 7.6 among streams,
with 91% very close to 7.5, a value suggested as the optimum for algal growth. In contrast, periphyton C:P ratios ranged from
122 to >700 (mean = 248, twice Redfield). Algal-P concentrations were significantly greater in urban streams, but data suggest
algal growth was P-limited in most streams regardless of degree of urbanization. GIS models indicate that land-use effects
did not easily fit into strict categories, but varied continuously from rural to urban conditions. We propose that the gradient
approach is the most effective method to characterize the influence of land use and urbanization on periphyton and stream
function. 相似文献
7.
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
8.
Headwater streams are key sites of nutrient and organic matter processing and retention, but little is known about temporal
variability in gross primary production (GPP) and ecosystem respiration (ER) rates as a result of the short duration of most
metabolism measurements in lotic ecosystems. We examined temporal variability and controls on ecosystem metabolism by measuring
daily rates continuously for 2 years in Walker Branch, a first-order deciduous forest stream. Four important scales of temporal
variability in ecosystem metabolism rates were identified: (1) seasonal, (2) day-to-day, (3) episodic (storm-related), and
(4) inter-annual. Seasonal patterns were largely controlled by the leaf phenology and productivity of the deciduous riparian
forest. Walker Branch was strongly net heterotrophic throughout the year with the exception of the open-canopy spring when
GPP and ER rates were co-equal. Day-to-day variability in weather conditions influenced light reaching the streambed, resulting
in high day-to-day variability in GPP particularly during spring (daily light levels explained 84% of the variance in daily
GPP in April). Episodic storms depressed GPP for several days in spring, but increased GPP in autumn by removing leaves shading
the streambed. Storms depressed ER initially, but then stimulated ER to 2–3 times pre-storm levels for several days. Walker
Branch was strongly net heterotrophic in both years of the study, with annual GPP being similar (488 and 519 g O2 m−2 y−1 or 183 and 195 g C m−2 y−1) but annual ER being higher in 2004 than 2005 (−1,645 vs. −1,292 g O2 m−2 y−1 or −617 and −485 g C m−2 y−1). Inter-annual variability in ecosystem metabolism (assessed by comparing 2004 and 2005 rates with previous measurements)
was the result of the storm frequency and timing and the size of the spring macroalgal bloom. Changes in local climate can
have substantial impacts on stream ecosystem metabolism rates and ultimately influence the carbon source and sink properties
of these important ecosystems. 相似文献
9.
Nitrogen and phosphorus are the primary nutrients that affect water quality in streams in the midwestern USA and high concentrations
of these nutrients tend to increase algal biomass. However, how nutrients interact with physical controls in regulating algal
biomass is not well known in agricultural streams. Eighteen streams in east-central Illinois (USA) were sampled during June
and September 2003 to analyze factors possibly regulating algal biomass. Additionally, two shaded and two non-shaded sites
in the Embarras River in east-central Illinois were sampled intensively from June to December 2003. Both sestonic and periphytic
chlorophyll-a (chl-a) were analyzed, and periphytic chl-a was assessed on natural substrata and unglazed ceramic tiles. Although high concentrations of nutrients were found in these
streams (mean total P = 0.09–0.122 mg l−1 and mean NO3-N=4.4–8.4 mg l−1), concentrations of sestonic chl-a were low among all sites and both sampling periods (<18 mg m−3, median values of 5 and 3 in June and September, respectively). Filamentous algae were an important component of the algal
communities in streams with stable substrata. Periphytic chl-a was generally not related to the concentration of N or P in the water column, and in non-shaded streams periphyton appeared
at times to be light-limited due to turbid water. Turbidity was found to be an important factor controlling chl-a on ceramic tiles across the 18 sites and for the Embarras River sites; chl-a decreased exponentially in concentration (132–0 mg m−2) as turbidity increased from 4 to 39 NTU (r
2 = 0.80). In general, the interaction between hydrology and light (turbidity) likely controlled algal biomass in these nutrient-rich,
agricultural streams. 相似文献
10.
Martin Emil Blicher Lars Maltha Rasmussen Mikael Kristian Sejr Flemming Ravn Merkel S?ren Rysgaard 《Polar Biology》2011,34(8):1105-1116
The number of common eiders (Somateria
mollissima borealis) in west Greenland declined dramatically during the twentieth century, supposedly because of human activities. However, their
sensitivity to alternative drivers of variation, such as climate conditions, diseases or food availability, remains unstudied.
In this study, we describe prey availability and assess the trophic coupling between eiders and their macrobenthic prey in
a shallow inlet, Nipisat Sound; a key wintering habitat in the south-west Greenland Open Water Area. Macrobenthic species
abundance and biomass were studied, and annual production was estimated by an empirical model, including environmental characteristics,
fauna composition and individual biomass. In spring 2008, average macrozoobenthic abundance and biomass were 6,912 ind m−2 and 28.4 g ash-free dry mass (AFDM) m−2 (647 kJ m−2), respectively. Annual production was estimated at 13.9 g AFDM m−2 year−1 (317 kJ m−2 year−1). During the winters of 2008–2010, we monitored the number of common eiders (S. mollissima borealis) and king eiders (Somateria spectabilis) and observed a distinct peak in abundance during winter with up to 15.000 birds in Nipisat Sound. Based on physiological
costs of different activities in combination with the observed behavioural pattern, we obtained an estimate of the energy
required for eiders to balance their costs of living, which amounted to 58% of the estimated total annual production of macrobenthos
in Nipisat Sound. This result suggests that eider predation affects macrobenthic species composition and biomass and demonstrates
the potential importance of variations in prey availability for the population dynamics of eiders in Greenland. 相似文献
11.
Tropical island stream ecosystems continue to be threatened by increasing anthropogenic demands for freshwater, with many streams dammed or diverted. Stream flow amendments can have substantial effects on aquatic insect populations of tropical archipelagoes. In Hawaiian streams, an endemic Diptera community of the following genera dominates cascades and other torrential habitats: Telmatogeton Schiner (Chironomidae), Procanace Hendel (Canacidae), Scatella Robineau-Desvoidy (Ephydridae). Larval densities, standing stock biomass (SSB, as ash-free dry mass [AFDM]), and monthly secondary production of Telmatogeton and Procanace were measured during two summers of significantly different stream discharge in Iao Valley, Maui, Hawaii. Very few Scatella larvae were collected (<20 larvae for both years combined), so they were omitted from subsequent analyses. Stream discharge decreased approximately 40% from 1994 to 1995, providing a ‘natural test’ of the effects of reduced stream flow on these torrenticolous populations between two years. Combined Telmatogeton and Procanace SSB (total torrential community SSB) was 3176 and 1683 mg AFDM m−2 for 1994 and 1995, respectively, with Telmatogeton accounting for >95% in both years due to significantly larger body size and high density. The SSB of Telmatogeton significantly decreased from 3138 to 1622 mg AFDM m−2 from 1994 to 1995 but increased for Procanace (37.6–60.9 mg AFDM m−2, respectively). Total torrential community secondary production was 31% lower in 1994 (12,833 mg AFDM m−2 mo−1) compared to 1995 (8855 mg AFDM m−2 mo−1), reflecting the Telmatogeton proportion of total community production (99%); however, Procanace production increased by 40%. Monthly P/B ratios indicated that biomass turnover was generally high and increased for Telmatogeton from 1994 (3.8) to 1995 (5.1), whereas it remained lower and did not change between years for Procanace (1.7). A natural drought of the Iao Stream valley was associated with structural and functional changes in two endemic aquatic insects; these results are a conservative indication of permanent stream flow reductions from anthropogenic withdrawal (e.g., dams and diversions). 相似文献
12.
Light irradiation had remarkable effects on callus growth of Oldenlandia affinis with an optimum intensity of 35 μmol m−2 s−1. Biosynthesis of kalata B1, the main cyclic peptide in O. affinis, was induced and triggered with rising irradiation intensities. The highest concentration of kalata B1, 0.49 mg g−1 DW characterised by the maximum productivity of 3.88 μg per litre and day was analysed at 120 μmol m−2 s−1, although callus growth was repressed. The light saturation point was established to be 35 μmol m−2 s−1, where kalata B1 productivity was in a similar order (3.41 μg per day) due to the higher growth index. O. affinis suspension cultures were shown to accumulate comparable specific kalata B1 concentrations in a delayed growth associated
production pattern. These were dependent on irradiation intensity (0.16 mg g−1 at 2 μmol m−2 s−1; 0.28 mg g−1 at 35 μmol m−2 s−1). The batch cultivation process resulted in a maximum productivity of 27.30 μg per litre and day with culture doubling times
of 1.16 d−1. Submers operation represented a 8-fold product enhancement compared to callus cultivation. 相似文献
13.
Effect of riparian land use on contributions of terrestrial invertebrates to streams 总被引:2,自引:1,他引:1
Since terrestrial invertebrates are often consumed by stream fishes, land-use practices that influence the input of terrestrial invertebrates to streams are predicted to have consequences for fish production. We studied the effect of riparian land-use regime on terrestrial invertebrate inputs by estimating the biomass, abundance and taxonomic richness of terrestrial invertebrate drift from 15 streams draining catchments with three different riparian land-use regimes and vegetation types: intensive grazing — exotic pasture grasses (4 streams), extensive grazing — native tussock grasses (6 streams), reserve — native forest (5 streams). Terrestrial invertebrate drift was sampled from replicated stream reaches enclosed by two 1 mm mesh drift nets that spanned the entire channel. The mean biomass of terrestrial invertebrates that entered tussock grassland (12 mg ash-free dry mass m–2 d–1) and forest streams (6 mg AFDM m–2 d–1) was not significantly different (p > 0.05). However, biomass estimated for tussock grassland and forest streams was significantly higher than biomass that entered pasture streams (1 mg AFDM m–2 d–1). Mean abundance and richness of drifting terrestrial invertebrates was not significantly different among land-use types. Winged insects contributed more biomass than wingless invertebrates to both pasture and tussock grassland streams. Winged and wingless invertebrates contributed equally to biomass entering forest streams. Land use was a useful variable explaining landscape-level patterns of terrestrial invertebrate input for New Zealand streams. Evidence from this study suggests that riparian land-use regime will have important influences on the availability of terrestrial invertebrates to stream fishes. 相似文献
14.
We assessed the effect of salinity on plant growth and leaf expansion rates, as well as the leaf life span and the dynamics
of leaf production and mortality in seedlings of Avicennia germinans L. grown at 0, 170, 430, 680, and 940 mol m−3 NaCl. The relative growth rates (RGR) after 27 weeks reached a maximum (10.4 mg g−1 d−1) in 170 mol m−3 NaCl and decreased by 47 and 44% in plants grown at 680 and 940 mol m−3 NaCl. The relative leaf expansion rate (RLER) was maximal at 170 mol m−3 NaCl (120 cm m−2 d−1) and decreased by 57 and 52% in plants grown at 680 and 940 mol m−3 NaCl, respectively. In the same manner as RGR and RLER, the leaf production (P) and leaf death (D) decreased in 81 and 67% when salinity increased from 170 to 940 mol m−3 NaCl, respectively. Since the decrease in P with salinity was more pronounced than the decrease in D, the net accumulation of leaves per plant decreased with salinity. Additionally, an evident increase in annual mortality
rates (λ) and death probability was observed with salinity. Leaf half-life (t
0.5) was 425 days in plants grown at 0 mol m−3 NaCl, and decreased to 75 days at 940 mol m−3 NaCl. Thus, increasing salinity caused an increase in mortality rate whereas production of new leaves and leaf longevity
decreased and, finally, the leaf area was reduced. 相似文献
15.
Life history aspects of Ephemera orientalis, a common lowland burrowing mayfly that resides in temperate East Asia, were studied in terms of voltinism, secondary production,
and accumulated degree days for larval development. From March 1998 to June 1999, larvae were sampled monthly (weekly or biweekly
during the emergence period) from a lower reach of the Gapyeong stream in Korea, a stream typical of temperate East Asia,
using a Surber sampler (0.25 m2, mesh 0.25 mm). As a result, the mean density of E. orientalis was 47.21 ± 13.58 indiv. m−2 during the study period. Very small larvae less than 2 mm in body length were sampled on three separate occasions, and emergence
was observed between late April and early October, except during late May. Based on the larval body length distribution and
emergence time, two different developmental groups could be distinguished: the slow developmental group (S-group) and the
fast developmental group (F-group). The F-group completed its life cycle within 4 months, whereas the S-group had a one-year
life cycle. The S-group could be divided into two subgroups, dubbed the S1 and S2-groups, based on larval development. The
developmental groups alternate their life cycles in the order: S1→F→S2→S1. Estimated annual production of the larvae was 68.81 mg DW m−2 y−1; mean biomass was 8.43 mg DW m−2; the annual production to mean biomass ratio was 8.16. The annual mean water temperature of the study year was 14.76 ± 6.63°C.
The total accumulated degree days for larval development was 1396°C for the F-group, 2,055°C for the S1-group, and 1,975°C
for the S2-group. Two different adult body size groups were distinguished (P < 0.001 by t-test): larger adults, which belonged to the S-group, were present throughout the emergence period, whereas smaller adults,
which belonged to the F-group, were mainly present later in the emergence period (August–October). The difference in the accumulated
degree days between the developmental groups may explain the size differences of adults. 相似文献
16.
Methanogenesis in Arizona,USA dryland streams 总被引:1,自引:0,他引:1
Jeremy B. Jones Jr. Robert M. Holmes Stuart G. Fisher Nancy B. Grimm Dena M. Greene 《Biogeochemistry》1995,31(3):155-173
Methanogenesis was studied in five streams of central and southern Arizona by examining the distribution of methane in interstitial
water and evasion of methane in three subsystems (hyporheic, parafluvial and bank sediments). In Sycamore Creek, the primary
study site (studied during summer and early autumn), methane content of interstitial water exhibited a distinct spatial pattern.
In hyporheic (sediments beneath the wetted channel) and parfluvial zones (active channel sediments lateral to the wetted channel),
which were well oxygenated due to high hydrologic exchange with the surface stream and had little particulate organic matter
(POM), interstitial methane concentration averaged only 0.03 mgCH4-C/L. Bank sediments (interface between the active channel and riparian zone), in contrast, which were typically vegetated,
had high POM, low hydrologic exchange and concomitantly low dissolved oxygen levels, had interstitial concentration averaging
1.5 mgCH4-C/L. Methane emission from Sycamore Creek, similar to methane concentration, averaged only 3.7 mgCH4-C·m−2·d−1 from hyporheic and parafluvial zones as opposed to 170 mgCH4-C·m−2·d−1 from anoxic bank sediments. Methane in four additional streams sampled (one sampling date during late winter) was low and
exhibited little spatial variation most likely due to cooler stream temperatures. Interstitial methane in parafluvial and
bank sediments of all four streams ranged from only 0.005 to 0.1 mgCH4-C/L. Similarly methane evasion was also low from these streams varying from 0 to 5.7 mgCH4-C·m−2·d−1. The effects of organic matter and temperature on methanogenesis were further examined by experimentally manipulating POM
and temperature in stoppered flasks filled with hyporheic sediments and stream water. Methane production significantly increased
with all independent variables. Methane production is greatest in bank sediments that are relatively isolated hydrologically
and lowest in hyporheic and parafluvial sediments that are interactive with the surface stream. 相似文献
17.
Life-history and production of Olinga feredayi in both benthic and hyporheic stream habitats were investigated in a pristine Waikato, New Zealand, forest stream over two
years to investigate the contribution of hyporheic habitat to total secondary production. O. feredayi had a univoltine life-history with adult emergence occurring from November to March. Larvae with case lengths < 2 mm were
present on most dates suggesting delayed egg hatching. Benthic densities were inversely related to maximum peak daily flow
in the month prior to sampling, and positively related to the dry mass of particulate organic matter present in samples. Reach-average
benthic production calculated by the size-frequency method was 0.024 g DM m−2 year−1. Hyporheic production was 4.276 g DM m−3 year−1 and 6.462 g DM m−3 year−1 in colonisation baskets set at 15–30 cm and 30–45 cm within the substratum, respectively, 2.3–3.4 times greater than production
in surface baskets (0–15 cm). Averaged out over the reach scale, it was estimated that 96% of annual secondary production
of O. feredayi occurred in hyporheic habitats >10 cm below the streambed surface. Our study clearly demonstrates that only sampling benthic
habitats can lead to gross under-estimation of population-level annual production, and provides evidence for the role of the
hyporheos as a source of secondary production that may partly account for the Allen Paradox. 相似文献
18.
Malaysia is the world’s leading producer of palm oil products that contribute US$ 7.5 billion in export revenues. Like any
other agro-based industries, it generates waste that could be utilized as a source of organic nutrients for microalgae culture.
Present investigation delves upon Isochrysis sp. culture in POME modified medium and its utilization as a supplement to Nanochloropsis sp. in rotifer cultures. The culture conditions were optimized using a 1 L photobioreactor (Temp: 23°C, illumination: 180 ∼ 200 μmol
photons m−2s−1, n = 6) and scaled up to 10 L outdoor system (Temp: 26–29°C, illumination: 50 ∼ 180 μmol photons m−2s−1, n = 3). Algal growth rate in photobioreactor (μ = 0.0363 h−1) was 55% higher compared to outdoor culture (μ = 0.0163 h−1), but biomass production was 1.3 times higher in outdoor culture (Outdoor = 91.7 mg m−2d−1; Photobioreactor = 69 mg m−2d−1). Outdoor culture produced 18% higher lipid; while total fatty acids (FA) was not significantly affected by the change in
culture systems as both cultures yield almost similar concentrations of fatty acids per gram of sample (photobioreactor = 119.17 mg
g−1; outdoor culture = 104.50 mg g−1); however, outdoor cultured Isochrysis sp. had 26% more polyunsaturated fatty acids (PUFAs). Rotifers cultured in Isochrysis sp./ Nanochloropsis sp. (1:1, v/v) mixture gave similar growth rate as 100% Nanochoropsis sp. culture (μ = 0.40 d−1), but had 45% higher counts of rotifers with eggs (t = 7, maximum). The Isochrysis sp. culture successfully lowered the nitrate (46%) and orthophosphate (83%) during outdoor culture. 相似文献
19.
We estimated the secondary production of Rhyacophila minora, Ameletus sp., and Isonychia bicolor in three acidic streams and one circumneutral stream in Randolph County, West Virginia. Quantitative benthic samples were collected monthly from these second-order streams from November 1990 to October 1991. Mean pH values in the acidic streams were 4.5, 4.8, and 4.8, and mean pH in the circumneutral stream was 6.7. Production estimates for Rhyacophia minora in the acidic streams were 49.6, 19.2, and 15.8 mg m–2 y–1. Production of R. minora in the circumneutral stream was 1.0 mg m–2 y–1. Ameletus sp. production estimates for the acidic streams were 144.8, 176.8, and 208.3 mg m–2 y–1. Ameletus sp. production in the circumneutral stream was 7.4 mg m–2 y–1. Secondary production of I. bicolor in the circumneutral stream was 116.6 mg m–2 y–1. No Isonychia were collected from the acidic streams. The higher production of R. minora and Ameletus sp. in the acidic streams may be associated with differences in macroinvertebrate community structure. 相似文献
20.
Understanding the interactions between terrestrial and aquatic ecosystems remains an important research focus in ecology.
In arid landscapes, catchments are drained by a channel continuum that represents a potentially important driver of ecological
pattern and process in the surrounding terrestrial environment. To better understand the role of drainage networks in arid
landscapes, we determined how stream size influences the structure and productivity of riparian vegetation, and the accumulation
of organic matter (OM) in soils beneath plants in an upper Sonoran Desert basin. Canopy volume of velvet mesquite (Prosopis velutina), as well as overall plant cover, increased along lateral upland–riparian gradients, and among riparian zones adjacent to
increasingly larger streams. Foliar δ13C signatures for P. velutina suggested that landscape patterns in vegetation structure reflect increases in water availability along this arid stream
continuum. Leaf litter and annual grass biomass production both increased with canopy volume, and total aboveground litter
production ranged from 137 g m−2 y−1 in upland habitat to 446 g m−2 y−1 in the riparian zone of the perennial stream. OM accumulation in soils beneath P. velutina increased with canopy volume across a broad range of drainage sizes; however, in the riparian zone of larger streams, flooding
further modified patterns of OM storage. Drainage networks represent important determinants of vegetation structure and function
in upper Sonoran Desert basins, and the extent to which streams act as sources of plant-available water and/or agents of fluvial
disturbance has implications for material storage in arid soils. 相似文献