We initiated a multi-factor global change experiment to explore the effects of infrared heat loading （HT） and water table level （WL） treatment on soil temperature （T） in bog and fen peatland mesocosms. We found ...We initiated a multi-factor global change experiment to explore the effects of infrared heat loading （HT） and water table level （WL） treatment on soil temperature （T） in bog and fen peatland mesocosms. We found that the temperature varied highly by year, month, peatland type, soil depth, HT and WL manipulations. The highest effect of HT on the temperature at 25 cm depth was found in June for the bog mesocosms （3.34-4.27 ℃） but in May for the fen mesocosms （2.32-4.33 ℃） over the 2-year study period. The effects of WL in the bog mesocosms were only found between August and January, with the wet mesocosms warmer than the dry mesocosms by 0.48-2.03 ℃ over the 2-year study period. In contrast, wetter fen mesocosms were generally cooler by 0.16-3.87℃. Seasonal changes of temperatures elevated by the HT also varied by depth and ecosystem type, with temperature differences at 5 cm and 10 cm depth showing smaller seasonal fluctuations than those at 25 cm and 40 cm in the bog mesocosms. However, increased HT did not always lead to warmer soil, especially in the fen mesocosms. Both HT and WL manipulations have also changed the length of the non-frozen season.展开更多
A mesocosm-based study was conducted to assess the effect of glucose and hydrogen peroxide on periphyton communities. These chemicals have been found to be effective at controlling cyanobacteria blooms in the water co...A mesocosm-based study was conducted to assess the effect of glucose and hydrogen peroxide on periphyton communities. These chemicals have been found to be effective at controlling cyanobacteria blooms in the water column but their impact on attached communities is unknown. The experimental design included a total of 4 treatments: control (no chemicals;3 replicates);hydrogen peroxide (3 replicates);glucose alone (3 different concentrations [no replicates]);and additive glucose (3 replicates). After 34 days, mean values of chlorophyll a were lower in all experimental treatments compared to the control;mean AFDM values were lower in all treatments except the unreplicated high glucose alone treatment. In contrast, mean autotrophic index values (AFDM/chlorophyll a) were greater in all treatments compared to the control, indicating heterotrophs were more resistant to the chemical treatments than autotrophs. Periphyton community biodiversity was much lower in the additive glucose and moderate glucose alone treatments than the hydrogen peroxide and control treatments. The relative abundance of the bacteria Asticcacaulis and Sphingorhabdus responded positively to the glucose treatments, whereas relative abundance of Nevskia and Caenimonas declined in both the hydrogen peroxide and glucose treatments. In terms of relative abundance, no cyanobacteria taxa were detected among the top 20 taxa. We conclude that the autotrophic component of periphyton communities is especially vulnerable to hydrogen peroxide and glucose treatments, and that any management strategy employing these chemicals should be aware of this potential impact.展开更多
A series of enclosed ecosystem experiments were conducted in a land based tank near the seaside of West Xiamen Harbor.The results of experiments conducted in different seasons and years showed a repeatble phytoplankto...A series of enclosed ecosystem experiments were conducted in a land based tank near the seaside of West Xiamen Harbor.The results of experiments conducted in different seasons and years showed a repeatble phytoplankton succession. In this relatively stable ecosystem with added nutrients and trace metals,diatoms dominated initially,dinoflagellates dominated in the later stage,and dinoflagellate red tides eventually occurred.Vitamin B 12 enrichment may speed up this succession process. Stirring the water column could stop this process. Soluble Mn at a level of 3-4 μg/L in seawater,which also is the existing concentration of solu ble Mn in Xiamen Harbor seawater,is sufficient for the multiplication of algae and occurrence of red tide.The present study showed that excessive soluble Mn in Xiamen Harbor cannot cause red tide,and that Fe was one of the important factors causing diatom red tide in this present study..展开更多
A algal bloom process had been simulated via field mesocosm experiment, and the change of phytoplankton assemblage of different sizes in different growing phases had been studied. Nutrients addition could promote the ...A algal bloom process had been simulated via field mesocosm experiment, and the change of phytoplankton assemblage of different sizes in different growing phases had been studied. Nutrients addition could promote the growth of phytoplankton In the mesocosm of Prorocentrum donghaiense （M1） and the mesocosm of natural waters （M2）, and the peaks of chlorophyll a were 112.79 mg/m and 235.60 mg/m, respectively. The restraining effect of nano-phytoplankton on pico-phytoplankton growth was stronger in M2 than in M1. When nutrients were abundant, the relative growth rate of diatom was higher than that of P. donghaiense, and they reached the peak quickly and then came to die out very fast. The decreasing of Si promoted diatom bloom to die out.展开更多
A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting （Hyperiodrilus africanus, Eudrilidae） and two compacting （Millsonia omodeoi ...A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting （Hyperiodrilus africanus, Eudrilidae） and two compacting （Millsonia omodeoi and Dichogaster terrae nigrae, Acanthodrilidae） earthworm species on soil properties. These species have been selected for their predominance in the re- gion and their contrasting impact on soil structure. The experimental design consisted of a treatment without worms （control）, and treatments with one, two or three species of earthworms. Both compacting and decompacting earthworms increased water infil- tration rate in all treatments, with marked impact in H. africanus and M. omodeoi＋D, terraenigrae treatments. Interactions be- tween compacting and decompacting species resulted in more large aggregates in comparison to when the compacting species D. terraenigrae was alone. This may be accounted for by their compacting attribute as compacting earthworms are responsible for producing the highest number of large aggregates. The low values of mean weight diameter in treatments combining decompact-ing and compacting earthworms compared with compacting ＂M. omodeoi＂ one also confirmed the trend of decline in soil com-paction in the presence of the decompacting species. These results showed positive impact of species richness on soil structure regulation, which is crucial in ecosystem productivity and support consequently the insurance hypothesis. In fact, this study showed that the preservation of earthworm species belonging to these two contrasting functional groups is essential for the main-tenance of stable soil structure regulation in agro-tropical ecosystems.展开更多
Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms...Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms（HABs）.The results showed that there was interspecies competition between P.donghaiense and Skeletonema costatum（Grev.） Cleve.The cell number of P.donghaiense and S.costatum accounted for about 85% and 11% of the total cell number of phytoplankton respectively at the beginning of the experiment in May 1998.In May 2002,at the beginning of the experiment,the cell number of P.donghaiense accounted for 55%-66% of the total and S.costatum accounted for 32%-42%.The density of P.donghaiense and S.costatum was over 95% and 1%-5% respectively in May 2003.The results of these three mesocosm experiments showed that the dominant species in this specific community varied with different nutrient availability.Under low-phosphate conditions,the dominant species was P.donghaiense,while S.costatum became dominant in phosphate-replete cases.The average growth rate（1.08 d-1） of S.costatum in exponential growth phase was higher than that（0.39 d-1） of P.donghaiense.In the mesocosm,S.costatum predominated in the mesocosm by its rapid growth.When phosphorus was depleted,the cell number of S.costatum dropped rapidly,while P.donghaiense Lu decreased more slowly.The results from mesocosm experiment may explain why：（1） P.donghaiense bloom usually occurs in May,when phosphate concentration is low;（2） the bloom of S.costatum appears in early spring and summer time,when nutrients increase with increasing Changjiang River（Yangtze River） runoff;（3） the bloom of S.costatum is short and that of P.donghaiense Lu can last more than a month in the East China Sea.展开更多
A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem was established according to the summary and synthesis of the models available, in which seven state variables （DIN, PO4-P, DON, DOP, phytoplankto...A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem was established according to the summary and synthesis of the models available, in which seven state variables （DIN, PO4-P, DON, DOP, phytoplankton, zooplankton and detritus） were included. Logically it had five modules--phytoplankton, zooplankton, dissolved inorganic nutrients, dissolved organic nutrients and detritus. The results showed that this model could simulate the variations of DIN, PO4-P, DON, DOP, POC and phytoplankton biomass in pelagic ecosystem in mesocosm properly, based on the site experiment data in the Jiaozhou Bay in the autumn of 1999 and the summer of 2000. Not only the logical structure but also the model parameters were feasible, and about 20 parameters were made to fit for the Jiaozhou Bay during the simulation. All of these are necessary to study the control mechanism of nutrients biogeochemical cycling in the Jiaozhou Bay and other China＇ s coastal waters.展开更多
A model of nitrogen and phosphorus dynamics in mesocosm experiments was established on the basis of a summary and synthesis of the existing models. The established model comprised seven state variables(DIN,PO4-P,DON,D...A model of nitrogen and phosphorus dynamics in mesocosm experiments was established on the basis of a summary and synthesis of the existing models. The established model comprised seven state variables(DIN,PO4-P,DON,DOP,phytoplankton,zooplankton and detritus) and five modules - phytoplankton,zooplankton,dissolved inorganic nutrients,dissolved organic nutrients and detritus. Comparison with the in situ experimental data in Laizhou Bay at the end of August 2002 showed that this model could properly simulate the variations of DIN,PO4-P,and phytoplankton biomass in a mesocosm pelagic ecosystem. It was found that not only the model structure but also the parameters adopted were fit for simulation. The sensitivity of the main state variables to the parameter change was assessed by sensitivity analysis. All these results are useful for studying the control mechanism of biogeochemical cycling of nutrients in Laizhou Bay and other Chinese coastal waters.展开更多
By the year 2050,the population of the United States is expected to reach over 418 million,while the global population will reach 9.6 billion.To provide safe food and fiber,agriculture must balance pesticide usage aga...By the year 2050,the population of the United States is expected to reach over 418 million,while the global population will reach 9.6 billion.To provide safe food and fiber,agriculture must balance pesticide usage against impacts on natural resources.Challenges arise when storms cause runoff to be transported to aquatic receiving systems.Vegetated systems such as drainage ditches and constructed wetlands have been proposed as management practices to alleviate pesticide runoff.Twelve experimental mesocosms(1.3±0.71±0.61 m)were filled with sediment and planted with a monoculture of one of three wetland plant species(Typha latifolia,Leersia oryzoides,and Sparganium arnericanurn).Three mesocosms remained unvegetated to serve as controls.All mesocosms were amended with 9.2±0.8μg/L,12±0.4μg/L,and 3.1±0.2μg/L of atrazine,metolachlor,and diazinon,respectively,over a 4 hr hydraulic retention time to simulate storm runoff.Following the 4 hr amendment,non-amended water was flushed through mesocosms for an additional 4 hr.Outflow water samples were taken hourly from pre-amendment through 8 hr,and again at 12,24,48,72,and 168 hr post-amendment.L.oryzoides and T.latifolia had mean atrazine,metolachlor,and diazinon retentions from B1%-55%for the first 4 hr of the experiment.Aside from S.arnericanum and atrazine(25%retention),unvegetated controls had the lowest pesticide retention(17%-28%)of all compared mesocosms.While native aquatic vegetation shows promise for mitigation of pesticide runoff,further studies increasing the hydraulic retention time for improved efficiency should be examined.展开更多
Whether it is necessary to reduce nitrogen(N) and/or phosphorus(P) input to mitigate lake eutrophication is controversial. The controversy stems mainly from differences in time and space in previous studies that suppo...Whether it is necessary to reduce nitrogen(N) and/or phosphorus(P) input to mitigate lake eutrophication is controversial. The controversy stems mainly from differences in time and space in previous studies that support the contrasting ideas. To test the response of phytoplankton to various combinations of nutrient control strategies in mesocosms and the possibility of reflecting the conditions in natural ecosystems with short-term experiments, a 9-month experiment was carried out in eight 800-L tanks with four nutrient level combinations(+N+P,-N+P, +N-P, and-N-P), with an 18-month whole-ecosystem experiment in eight ~800-m^2 ponds as the reference. Phytoplankton abundance was determined by P not N, regardless of the initial TN/TP level, which was in contrast to the nutrient limitation predicted by the N/P theory. Net natural N inputs were calculated to be 4.9, 6.8, 1.5, and 3.0 g in treatments +N+P,-N+P, +N-P, and-N-P, respectively, suggesting that N deficiency and P addition may promote natural N inputs to support phytoplankton development. However, the compensation process was slow, as suggested by an observed increase in TN after 3 weeks in-N+P and 2 months in-N-P in the tank experiment, and after 3 months in-N?+P and ~3 months in-N-P in our pond experiment. Obviously, such a slow process cannot be simulated in short-term experiments. The natural N inputs cannot be explained by planktonic N-fixation because N-fixing cyanobacteria were scarce, which was probably because there was a limited pool of species in the tanks. Therefore, based on our results we argue that extrapolating short-term, small-scale experiments to large natural ecosystems does not give reliable, accurate results.展开更多
Large benthic foraminifera are an integral component of shallow-water tropical habitats and like many marine calcifiers,are susceptible to ocean acidification(OA)and ocean warming(OW).In particular,the prolific Symbio...Large benthic foraminifera are an integral component of shallow-water tropical habitats and like many marine calcifiers,are susceptible to ocean acidification(OA)and ocean warming(OW).In particular,the prolific Symbiodiniaceae-bearing and high-magnesium calcite Marginopora vertebralis has a low threshold compared to several diatom-bearing and low-magnesium calcite species.In this multi-year mesocosm experiment,we tested three RPC 8.5 climate change scenarios(i)present day,(ii)the year 2050,and(iii)2100.To enable a realistic epiphytic association,these experiments were uniquely conducted using natural carbonate substrate,living calcifying alga,and seagrass.In contrast to previous studies,we detected no reduction in surface-area growth under future climate conditions compared with present day conditions.In terms of calcification,M.vertebralis’epiphytic association to primary producers(i.e.,calcifying algae and seagrasses)potentially ameliorates the effects of OA by buffering against declines in boundary layer pH during periods of photosynthesis(i.e.,CO_(2)removal).Importantly for population maintenance,we observed a strong reduction in asexual fecundity under the 2100 scenario.We propose the additional energy needed to maintain growth might be one reason for drastically reduced asexual reproduction.An alternative explanation could be that the 2℃temperature increase interfered with the environmental synchronization that triggered asexual multiple fission.We conclude that the low levels of reproduction will reduce populations in a high CO_(2)environment and reduce a valuable source of CaCO_(3) sediment production.展开更多
Planktonic metabolism plays an important role in affecting the energy transportation and carbon cycle of the marine ecosystem.However,its regulation mechanism remains unclear under the continuously exogenous nutrient ...Planktonic metabolism plays an important role in affecting the energy transportation and carbon cycle of the marine ecosystem.However,its regulation mechanism remains unclear under the continuously exogenous nutrient inputs in nearshore waters.In this study,a mesocosm experiment was conducted in a semi-enclosed bay,the Daya Bay,to explore the responses of plankton metabolic balance and community structure to a concentration gradient of daily nitrogen and phosphorus inputs.The results showed that nutrient enrichments promoted phytoplankton biomass,total primary production,and community respiration,and the promoting effect enhanced alongwith the increase of nutrient concentration.However,the net community production fluctuated more violently between autotrophic and heterotrophic with the increase of nutrient inputs and tended to be more heterotrophic from the 5 th day to the 10 th day of the experiment.In addition,the daily flux of nitrogen and phosphorus,2μmol/(L·d)and 0.066μmol/(L·d),respectively,could be regarded as a potential threshold for ecosystem stability and health,since most of the ecological characteristics related to plankton structure and function have undergone significant changes when the nutrient level is higher than that.In the nearshore enclosed or semi-enclosed waters,nutrient from continuous terrigenous input is likely to be concentrated and exceed this level,indicating the ecological risks due to the metabolic unbalance and the deterioration of plankton community structure.展开更多
Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs i...Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs in marine environment after an oil-spill incident.However,interaction between petroleum PAHs and microbial communities in a marine environment remains unclear.Therefore,a series of mesocosm experiments were conducted.in which water-accommodated fraction(WAF)of oil was generated to simulate an oil-spill scenario and to analyze the transport and behavior of marine oil spill containing PAHs with and without dispersants.Results indicate that the application of dispersant could increase the concentration of total PAHs in water column due mainly to significant increase in the concentration of highmolecular weight(HMW)PAHs at a lower removal rate.At the end of the 7-day experiment,significant amount of HMW PAHs were accumulated in sediment.In general,the application of dispersant did not increase the sediment uptake of PAHs but increased the PAHs concentration in water column.展开更多
Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of m...Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of mesocosm experiments are carried out to assess the impact of different concentrations of copper on benthic foraminiferal assemblages over time. This pilot investigation documents that Cu contamination has a detrimental effect on foraminifera when compared to original and control samples. In particular, increased concentrations of Cu (normally higher than 120 μg/l) lead to a lowering of foraminiferal density and diversity and an increased occurrence of abnormalities. This study thus supports that the use of an experimental approach is suitable for investigating the response of benthic foraminifera to stress including pollution. Moreover, the application of mesocosms represents an innovative tool to be placed alongside field studies and culture experiments.展开更多
In order to better understand the effects of biostimulation and bioaugmentation processes on a marine microbial community, three different mesocosm experiments were planned. Natural seawater（10.000 L） was artificial...In order to better understand the effects of biostimulation and bioaugmentation processes on a marine microbial community, three different mesocosm experiments were planned. Natural seawater（10.000 L） was artificially polluted with crude oil（1 L） and（1） inorganic nutrients（Biostimulating Mesocosm, BM）,（2） inorganic nutrients and an inoculum of Alcanivorax borkumensis SK2（Single Bioaugmentation Mesocosm, SBM）,（3） inorganic nutrients and inoculums of A. borkumensis SK2 and Thalassolituus oleivorans MIL-1（Consortium Bioaugmentation Mesocosm, CBM）. During the experimental period（20 days）, samples were taken from each mesocosm and the community structure was analyzed by PCR–DGGE. The 16 S r RNA gene DGGE banding patterns and sequence analysis demonstrated that biostimulation had the lowest effect on microbial biodiversity in the mesocosms; however, the biodiversity of the marine microbial community dramatically decreased in the CBM（Shannon index was 0.6 in T3）. The community structures among the three mesocosms were also markedly different,and major bacteria derived from DGGE bands were related to uncultured Gamma Proteobacteria. The biodegradation results show that the Single Bioaugmentation Mesocosm（SBM） system had the highest percentage of degradation（95%） in comparison to the BM mesocosm（80%） and CBM（70%）.展开更多
Soil macroinvertebrates are highly diverse and their major ecological service include breakdown of organic matter and in turn improve soil fertility and pill-millipedes are well-known for their significant role in ing...Soil macroinvertebrates are highly diverse and their major ecological service include breakdown of organic matter and in turn improve soil fertility and pill-millipedes are well-known for their significant role in ingestion, disintegration and decomposition of organic matter in soil. This study characterized the feed, the decomposing leaf litter of coconut （Cocos nucifera）, and faeces of two endemic giant pill-millipedes Arthrosphaera disticta and A. fumosa collected from forests of the Western Ghats of India based on chemical features and microbial profile. In both millipedes, electric conductivity and total phosphorus were significantly increased in faeces, while the crude protein, organic carbon, total nitrogen and total phenolics were significantly decreased, as compared to those in feed. Heterotrophic bacteria, actinomycetes, rhizobia and phosphate-solubilizing bacteria were significantly higher in faeces than in feed, while filamentous fungi and yeast substantially decreased in faces compared to feed in both the millipedes. Spectrum of fatty acid methyl esters was considerably different between feed and faeces of both the millipedes. The total saturated fatty acids were higher than the total unsaturated fatty acids in feed as well as faeces, while the ratio of unsaturated/saturated fatty acids decreased from feed to faeces. Dodecanoic and tetradecanoic acids in A. disticta and octadecanoic acid in A. fumosa significantly increased, while （9Z）-octadec-9-enoic and （9E,12E）-octadeca-9,12-dienoic acids in A.. disticta and hexadecanoic, tetracosanoic and （9E,12E）- octadeca-9,12-dienoic acids in A. fumosa significantly decreased in faeces compared to feed, indicating millipede-dependent changes in fatty acids. Icosanoic acid was present in faeces of both the millipedes, and hexadec-9-enoic acid was confined to faeces of A disticta, while pentadecanoic, heneicosanoic, （9Z,12Z,15Z）-9,12,15-octadecatrienoic and eicosenoic acids were confined to faeces of A. fumosa. Pill-millipedes enrich the soil quality by leaf litter conditioning in their gut through specific microbial communities. Fingerprinting of fatty acid methyl esters in faeces of these millipedes reflected the activity of specific microbial population in their guts.展开更多
The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton...The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton community respiration rate fluctuated between 0.07 and 2.28 mgC/(L·d), average of 0.82±0.42 mgC/(L·d), which was 49 percent of the rate of phytoplankton gross production;that the average respiration rates (mgC/(L·d)) of micro , nano and pico plankton were 0.07, 0.38 and 0.31, which were 175, 30 and 207 percent of the corresponding sized phytoplankton production rates; that the sediment respiration rate (mgC/(m 2·d)) varied from 178.64 to 373.23, average of 262.60±48.68, and increased gradually with the lapse of culture time; and that the organic carbon accumulation and the respiration in the sediment of the shrimp monoculture mesocosm was higher than that in the polyculture mesocosms. The total sediment respiration per 25 m 2 mesocosm in the culture period averaged 571.16 gC, which was 10 percent of the total organic carbon input of the mesocosm.展开更多
Indaziflam is a preemergent herbicide widely used for the control of weeds in pecan(Carya illinoinensis)orchards in the southwestern region of the United States.Given the paucity of data regarding the effect of indazi...Indaziflam is a preemergent herbicide widely used for the control of weeds in pecan(Carya illinoinensis)orchards in the southwestern region of the United States.Given the paucity of data regarding the effect of indaziflam on the biochemical properties of soils supporting pecan production,this study was conducted to evaluate the effects of different application rates of indaziflam on soil microbial activity,diversity,and biochemical processes related to nitrogen(N)cycling.During two consecutive growing seasons(2015 and 2016),soil samples were obtained from experimental mesocosms consisting of soil-filled pots where pecan saplings were grown and treated with indaziflam applied at two different rates(25 and 50 g active ingredient(ai)ha^(-1),with the higher rate being slightly lower than the recommended field application rate of 73.1 g ai ha^(-1)).Soil samples were collected approximately one week before and one week after herbicide application for determination of soil microbial biomass and diversity,N mineralization,andβ-glucosaminidase activity.Soil samples collected from the control mesocosms without herbicide application were treated in the laboratory with two rates of indaziflam(75 and 150 g ai ha^(-1))to determine the immediate effect on microbial activity.No significant effect of herbicide treatment on soil respiration and microbial biomass was detected.The results showed a slight to moderate decrease in microbial diversity(7%in 2015 and 44%in 2016).However,decreasedβ-glucosaminidase activity with herbicide treatment was observed in soils from the mesocosms(33%)and soils treated with indaziflam in the laboratory(45%).The mineral N pool was generally dominated by ammonium after indaziflam application,which was consistent with the drastic decrease(75%)in nitrification activity measured in the laboratory experiment.The results of this study indicate that indaziflam,even when applied at higher than recommended rates,has limited effects on soil microbial activity,but may affect N cycling processes.展开更多
Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks （40 m3） for fish larvae production at low densities （2-8 larvae/L）, with live prey production within the tank supplem...Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks （40 m3） for fish larvae production at low densities （2-8 larvae/L）, with live prey production within the tank supplemented by exogenous sources of feed. Due to the high biological quality of larvae produced and low level of technological input, these methodologies are regarded as an interesting option to meet the increasing fry demand from the aquaculture industry. This study aimed to describe the experience at Centro de Maricultura da Calheta, Madeira Island, Portugal, with the establishment of a mesocosm hatchery for the production of marine fish larvae. Production trials were initiated with gilthead seabream Sparus aurata. This larval species presented faster growth in total body length （TL） per day （TL = 3.7516e~ ~293day, R2 = 0.9404）, higher survival rate （SR = 31.9%） and comparable swimbladder inflation rates （SB = 90%） to those of larvae reared with intensive methodologies. High larval performance was obtained with two candidate species for aquaculture： the red porgy Pagruspagrus （TL = 3.212e~~39day, R2 = 0.995; SR = 15.3%; SB = 95.7%） and the white seabream Diplodus sargus （TL = 3.6355e~~413day, R2= 0.9824; SR = 25%; SB --- 100%）. Testing ofa 110 m3 mesocosm rearing tank with white seabream larvae revealed limitations associated to larger tanks namely, the amount and quality of live feed required daily. First trials with striped jack （Pseudocararoc dentex） larvae resulted in low larval survival （0.04%）, but the use of a white tank avoided culture management constraints related to positive phototropism. The present results suggest that a mesocosm using semi-intensive methodologies may contribute to species diversification and consequently, to the sustainable development of aquaculture.展开更多
In this paper, we constructed the halophyte Mesocosm experimental group which was used as a substrate material that consisted of tidal flat and dredged sediment. Depending on whether the ingredients of vegetation and ...In this paper, we constructed the halophyte Mesocosm experimental group which was used as a substrate material that consisted of tidal flat and dredged sediment. Depending on whether the ingredients of vegetation and substrate material of Mesocosm, we constructed Mesocosm A (tidal flat sediment + Salicornia herbecea), Mesocosm B (only dredged sediment), Mesocosm C (dredged sediment + Salicornia herbecea). Monitoring was carried out of seawater quality factors (Chemical Oxygen Demand (COD), Total Nitrogen (T-N), Total Phosphorus (T-P), temperature, salinity), sediment factors (Chemical Oxygen Demand (COD), Total (T-N), Total Phosphorus (T-P) and growth of Salricornia herbecea) in each Mesocosm. Habitat Stability Index of vegetation was calculating by using the monitoring results. HSI of Mesocosm C was calculated from 0.87 to 0.95 as compared to the relatively high HSI Mesocosm A, it was evaluated to be able to be used in the restoration of the coastal salt marsh with dredged sediment.展开更多
基金Supported by the National Science Foundation (DEB9707426).
文摘We initiated a multi-factor global change experiment to explore the effects of infrared heat loading （HT） and water table level （WL） treatment on soil temperature （T） in bog and fen peatland mesocosms. We found that the temperature varied highly by year, month, peatland type, soil depth, HT and WL manipulations. The highest effect of HT on the temperature at 25 cm depth was found in June for the bog mesocosms （3.34-4.27 ℃） but in May for the fen mesocosms （2.32-4.33 ℃） over the 2-year study period. The effects of WL in the bog mesocosms were only found between August and January, with the wet mesocosms warmer than the dry mesocosms by 0.48-2.03 ℃ over the 2-year study period. In contrast, wetter fen mesocosms were generally cooler by 0.16-3.87℃. Seasonal changes of temperatures elevated by the HT also varied by depth and ecosystem type, with temperature differences at 5 cm and 10 cm depth showing smaller seasonal fluctuations than those at 25 cm and 40 cm in the bog mesocosms. However, increased HT did not always lead to warmer soil, especially in the fen mesocosms. Both HT and WL manipulations have also changed the length of the non-frozen season.
文摘A mesocosm-based study was conducted to assess the effect of glucose and hydrogen peroxide on periphyton communities. These chemicals have been found to be effective at controlling cyanobacteria blooms in the water column but their impact on attached communities is unknown. The experimental design included a total of 4 treatments: control (no chemicals;3 replicates);hydrogen peroxide (3 replicates);glucose alone (3 different concentrations [no replicates]);and additive glucose (3 replicates). After 34 days, mean values of chlorophyll a were lower in all experimental treatments compared to the control;mean AFDM values were lower in all treatments except the unreplicated high glucose alone treatment. In contrast, mean autotrophic index values (AFDM/chlorophyll a) were greater in all treatments compared to the control, indicating heterotrophs were more resistant to the chemical treatments than autotrophs. Periphyton community biodiversity was much lower in the additive glucose and moderate glucose alone treatments than the hydrogen peroxide and control treatments. The relative abundance of the bacteria Asticcacaulis and Sphingorhabdus responded positively to the glucose treatments, whereas relative abundance of Nevskia and Caenimonas declined in both the hydrogen peroxide and glucose treatments. In terms of relative abundance, no cyanobacteria taxa were detected among the top 20 taxa. We conclude that the autotrophic component of periphyton communities is especially vulnerable to hydrogen peroxide and glucose treatments, and that any management strategy employing these chemicals should be aware of this potential impact.
文摘A series of enclosed ecosystem experiments were conducted in a land based tank near the seaside of West Xiamen Harbor.The results of experiments conducted in different seasons and years showed a repeatble phytoplankton succession. In this relatively stable ecosystem with added nutrients and trace metals,diatoms dominated initially,dinoflagellates dominated in the later stage,and dinoflagellate red tides eventually occurred.Vitamin B 12 enrichment may speed up this succession process. Stirring the water column could stop this process. Soluble Mn at a level of 3-4 μg/L in seawater,which also is the existing concentration of solu ble Mn in Xiamen Harbor seawater,is sufficient for the multiplication of algae and occurrence of red tide.The present study showed that excessive soluble Mn in Xiamen Harbor cannot cause red tide,and that Fe was one of the important factors causing diatom red tide in this present study..
基金National‘973’Program(2001CB409707)the Natural Science Foundation ofChina(No.40206016 and U0633007)+1 种基金the Key Program of National Natural Science Foundation of China(No.40531006)the Field Platform&Station Foundation of CAS.
文摘A algal bloom process had been simulated via field mesocosm experiment, and the change of phytoplankton assemblage of different sizes in different growing phases had been studied. Nutrients addition could promote the growth of phytoplankton In the mesocosm of Prorocentrum donghaiense （M1） and the mesocosm of natural waters （M2）, and the peaks of chlorophyll a were 112.79 mg/m and 235.60 mg/m, respectively. The restraining effect of nano-phytoplankton on pico-phytoplankton growth was stronger in M2 than in M1. When nutrients were abundant, the relative growth rate of diatom was higher than that of P. donghaiense, and they reached the peak quickly and then came to die out very fast. The decreasing of Si promoted diatom bloom to die out.
文摘A short term field mesocosm experiment was performed in semi-deciduous forest areas of Ivory Coast to assess the impact of a decompacting （Hyperiodrilus africanus, Eudrilidae） and two compacting （Millsonia omodeoi and Dichogaster terrae nigrae, Acanthodrilidae） earthworm species on soil properties. These species have been selected for their predominance in the re- gion and their contrasting impact on soil structure. The experimental design consisted of a treatment without worms （control）, and treatments with one, two or three species of earthworms. Both compacting and decompacting earthworms increased water infil- tration rate in all treatments, with marked impact in H. africanus and M. omodeoi＋D, terraenigrae treatments. Interactions be- tween compacting and decompacting species resulted in more large aggregates in comparison to when the compacting species D. terraenigrae was alone. This may be accounted for by their compacting attribute as compacting earthworms are responsible for producing the highest number of large aggregates. The low values of mean weight diameter in treatments combining decompact-ing and compacting earthworms compared with compacting ＂M. omodeoi＂ one also confirmed the trend of decline in soil com-paction in the presence of the decompacting species. These results showed positive impact of species richness on soil structure regulation, which is crucial in ecosystem productivity and support consequently the insurance hypothesis. In fact, this study showed that the preservation of earthworm species belonging to these two contrasting functional groups is essential for the main-tenance of stable soil structure regulation in agro-tropical ecosystems.
基金The National Natural Science Foundation of China under contract Nos 40490262 and 3730114the CEOHAB Research Project of Na-tional Key Basic Research Development Program("973") of China under contract No. 2001CB409700
文摘Three mesocosm experiments were conducted in the East China Sea during blooms of Prorocentrum donghaiense Lu in May of 1998,2002 and 2003 to examine the role of nutrients in the formation of these harmful algae blooms（HABs）.The results showed that there was interspecies competition between P.donghaiense and Skeletonema costatum（Grev.） Cleve.The cell number of P.donghaiense and S.costatum accounted for about 85% and 11% of the total cell number of phytoplankton respectively at the beginning of the experiment in May 1998.In May 2002,at the beginning of the experiment,the cell number of P.donghaiense accounted for 55%-66% of the total and S.costatum accounted for 32%-42%.The density of P.donghaiense and S.costatum was over 95% and 1%-5% respectively in May 2003.The results of these three mesocosm experiments showed that the dominant species in this specific community varied with different nutrient availability.Under low-phosphate conditions,the dominant species was P.donghaiense,while S.costatum became dominant in phosphate-replete cases.The average growth rate（1.08 d-1） of S.costatum in exponential growth phase was higher than that（0.39 d-1） of P.donghaiense.In the mesocosm,S.costatum predominated in the mesocosm by its rapid growth.When phosphorus was depleted,the cell number of S.costatum dropped rapidly,while P.donghaiense Lu decreased more slowly.The results from mesocosm experiment may explain why：（1） P.donghaiense bloom usually occurs in May,when phosphate concentration is low;（2） the bloom of S.costatum appears in early spring and summer time,when nutrients increase with increasing Changjiang River（Yangtze River） runoff;（3） the bloom of S.costatum is short and that of P.donghaiense Lu can last more than a month in the East China Sea.
基金The National Natural Science Foundation of China under contract No. 40490262the State Ocean Administration of China"908"Founda-tion under contract No. 908-02-02-03the Science and Technology Development Plan of Qingdao of China under contract No. 06-2-2-7-nsh
文摘A nitrogen and phosphorus dynamic model of mesocosm pelagic ecosystem was established according to the summary and synthesis of the models available, in which seven state variables （DIN, PO4-P, DON, DOP, phytoplankton, zooplankton and detritus） were included. Logically it had five modules--phytoplankton, zooplankton, dissolved inorganic nutrients, dissolved organic nutrients and detritus. The results showed that this model could simulate the variations of DIN, PO4-P, DON, DOP, POC and phytoplankton biomass in pelagic ecosystem in mesocosm properly, based on the site experiment data in the Jiaozhou Bay in the autumn of 1999 and the summer of 2000. Not only the logical structure but also the model parameters were feasible, and about 20 parameters were made to fit for the Jiaozhou Bay during the simulation. All of these are necessary to study the control mechanism of nutrients biogeochemical cycling in the Jiaozhou Bay and other China＇ s coastal waters.
基金supported by the the State Ocean Ad-ministration of China ‘908’ Foundation (No. 908-02-02- 03)the State Ocean Administration of China Foundation (No. 200805065)+1 种基金the Scientific Research Launching Foundation for Introduced Talents of Ocean University of Chinathe Scientific and Technical Projects of Shandong Province on Environmental Protection (No. [2006]050)
文摘A model of nitrogen and phosphorus dynamics in mesocosm experiments was established on the basis of a summary and synthesis of the existing models. The established model comprised seven state variables(DIN,PO4-P,DON,DOP,phytoplankton,zooplankton and detritus) and five modules - phytoplankton,zooplankton,dissolved inorganic nutrients,dissolved organic nutrients and detritus. Comparison with the in situ experimental data in Laizhou Bay at the end of August 2002 showed that this model could properly simulate the variations of DIN,PO4-P,and phytoplankton biomass in a mesocosm pelagic ecosystem. It was found that not only the model structure but also the parameters adopted were fit for simulation. The sensitivity of the main state variables to the parameter change was assessed by sensitivity analysis. All these results are useful for studying the control mechanism of biogeochemical cycling of nutrients in Laizhou Bay and other Chinese coastal waters.
文摘By the year 2050,the population of the United States is expected to reach over 418 million,while the global population will reach 9.6 billion.To provide safe food and fiber,agriculture must balance pesticide usage against impacts on natural resources.Challenges arise when storms cause runoff to be transported to aquatic receiving systems.Vegetated systems such as drainage ditches and constructed wetlands have been proposed as management practices to alleviate pesticide runoff.Twelve experimental mesocosms(1.3±0.71±0.61 m)were filled with sediment and planted with a monoculture of one of three wetland plant species(Typha latifolia,Leersia oryzoides,and Sparganium arnericanurn).Three mesocosms remained unvegetated to serve as controls.All mesocosms were amended with 9.2±0.8μg/L,12±0.4μg/L,and 3.1±0.2μg/L of atrazine,metolachlor,and diazinon,respectively,over a 4 hr hydraulic retention time to simulate storm runoff.Following the 4 hr amendment,non-amended water was flushed through mesocosms for an additional 4 hr.Outflow water samples were taken hourly from pre-amendment through 8 hr,and again at 12,24,48,72,and 168 hr post-amendment.L.oryzoides and T.latifolia had mean atrazine,metolachlor,and diazinon retentions from B1%-55%for the first 4 hr of the experiment.Aside from S.arnericanum and atrazine(25%retention),unvegetated controls had the lowest pesticide retention(17%-28%)of all compared mesocosms.While native aquatic vegetation shows promise for mitigation of pesticide runoff,further studies increasing the hydraulic retention time for improved efficiency should be examined.
基金Supported by the State Key Laboratory of Freshwater Ecology and Biotechnology(Nos.2014FB14,2011FBZ14)Science and Technology Support Program of Hubei Province(No.2015BBA225)the Youth Innovation Association of Chinese Academy of Sciences(No.2014312)to WANG Haijun
文摘Whether it is necessary to reduce nitrogen(N) and/or phosphorus(P) input to mitigate lake eutrophication is controversial. The controversy stems mainly from differences in time and space in previous studies that support the contrasting ideas. To test the response of phytoplankton to various combinations of nutrient control strategies in mesocosms and the possibility of reflecting the conditions in natural ecosystems with short-term experiments, a 9-month experiment was carried out in eight 800-L tanks with four nutrient level combinations(+N+P,-N+P, +N-P, and-N-P), with an 18-month whole-ecosystem experiment in eight ~800-m^2 ponds as the reference. Phytoplankton abundance was determined by P not N, regardless of the initial TN/TP level, which was in contrast to the nutrient limitation predicted by the N/P theory. Net natural N inputs were calculated to be 4.9, 6.8, 1.5, and 3.0 g in treatments +N+P,-N+P, +N-P, and-N-P, respectively, suggesting that N deficiency and P addition may promote natural N inputs to support phytoplankton development. However, the compensation process was slow, as suggested by an observed increase in TN after 3 weeks in-N+P and 2 months in-N-P in the tank experiment, and after 3 months in-N?+P and ~3 months in-N-P in our pond experiment. Obviously, such a slow process cannot be simulated in short-term experiments. The natural N inputs cannot be explained by planktonic N-fixation because N-fixing cyanobacteria were scarce, which was probably because there was a limited pool of species in the tanks. Therefore, based on our results we argue that extrapolating short-term, small-scale experiments to large natural ecosystems does not give reliable, accurate results.
基金The Australian Government’s National Environmental Science Program(NESP)Tropical Water Quality(TWQ)Hub Projects 2.1.6 and 5.2:From exposure to risk:novel experimental approaches to analyse cumulative impacts and determine thresholds in the GBRWHA。
文摘Large benthic foraminifera are an integral component of shallow-water tropical habitats and like many marine calcifiers,are susceptible to ocean acidification(OA)and ocean warming(OW).In particular,the prolific Symbiodiniaceae-bearing and high-magnesium calcite Marginopora vertebralis has a low threshold compared to several diatom-bearing and low-magnesium calcite species.In this multi-year mesocosm experiment,we tested three RPC 8.5 climate change scenarios(i)present day,(ii)the year 2050,and(iii)2100.To enable a realistic epiphytic association,these experiments were uniquely conducted using natural carbonate substrate,living calcifying alga,and seagrass.In contrast to previous studies,we detected no reduction in surface-area growth under future climate conditions compared with present day conditions.In terms of calcification,M.vertebralis’epiphytic association to primary producers(i.e.,calcifying algae and seagrasses)potentially ameliorates the effects of OA by buffering against declines in boundary layer pH during periods of photosynthesis(i.e.,CO_(2)removal).Importantly for population maintenance,we observed a strong reduction in asexual fecundity under the 2100 scenario.We propose the additional energy needed to maintain growth might be one reason for drastically reduced asexual reproduction.An alternative explanation could be that the 2℃temperature increase interfered with the environmental synchronization that triggered asexual multiple fission.We conclude that the low levels of reproduction will reduce populations in a high CO_(2)environment and reduce a valuable source of CaCO_(3) sediment production.
基金the National Natural Science Foundation of China under contract No.41890853the Fund of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0404+3 种基金the Science&Technology Basic Resources Investigation Program of China under contract No.2018FY100105the Fund of Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences under contract No.ISEE2018ZD02the National Key Basic Research Program of China(973 Program)under contract No.2015CB452904the Development Project of China under contract Nos2017YFC0506302 and 2016YFC0502805。
文摘Planktonic metabolism plays an important role in affecting the energy transportation and carbon cycle of the marine ecosystem.However,its regulation mechanism remains unclear under the continuously exogenous nutrient inputs in nearshore waters.In this study,a mesocosm experiment was conducted in a semi-enclosed bay,the Daya Bay,to explore the responses of plankton metabolic balance and community structure to a concentration gradient of daily nitrogen and phosphorus inputs.The results showed that nutrient enrichments promoted phytoplankton biomass,total primary production,and community respiration,and the promoting effect enhanced alongwith the increase of nutrient concentration.However,the net community production fluctuated more violently between autotrophic and heterotrophic with the increase of nutrient inputs and tended to be more heterotrophic from the 5 th day to the 10 th day of the experiment.In addition,the daily flux of nitrogen and phosphorus,2μmol/(L·d)and 0.066μmol/(L·d),respectively,could be regarded as a potential threshold for ecosystem stability and health,since most of the ecological characteristics related to plankton structure and function have undergone significant changes when the nutrient level is higher than that.In the nearshore enclosed or semi-enclosed waters,nutrient from continuous terrigenous input is likely to be concentrated and exceed this level,indicating the ecological risks due to the metabolic unbalance and the deterioration of plankton community structure.
文摘Polycyclic aromatic hydrocarbons(PAHs)are one of the most important groups in oil,and re sponsible for major toxic and/or carcinogenic impact on humans and wildlife.It is important to understand the behavior of PAHs in marine environment after an oil-spill incident.However,interaction between petroleum PAHs and microbial communities in a marine environment remains unclear.Therefore,a series of mesocosm experiments were conducted.in which water-accommodated fraction(WAF)of oil was generated to simulate an oil-spill scenario and to analyze the transport and behavior of marine oil spill containing PAHs with and without dispersants.Results indicate that the application of dispersant could increase the concentration of total PAHs in water column due mainly to significant increase in the concentration of highmolecular weight(HMW)PAHs at a lower removal rate.At the end of the 7-day experiment,significant amount of HMW PAHs were accumulated in sediment.In general,the application of dispersant did not increase the sediment uptake of PAHs but increased the PAHs concentration in water column.
文摘Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of mesocosm experiments are carried out to assess the impact of different concentrations of copper on benthic foraminiferal assemblages over time. This pilot investigation documents that Cu contamination has a detrimental effect on foraminifera when compared to original and control samples. In particular, increased concentrations of Cu (normally higher than 120 μg/l) lead to a lowering of foraminiferal density and diversity and an increased occurrence of abnormalities. This study thus supports that the use of an experimental approach is suitable for investigating the response of benthic foraminifera to stress including pollution. Moreover, the application of mesocosms represents an innovative tool to be placed alongside field studies and culture experiments.
基金supported by the Shahid Bahonar University of Kerman and grants from EC Project “Unraveling and exploiting Mediterranean Sea microbial diversity and ecology for Xenobiotics' and pollutants' clean up” (No. ULIXES-FP7KBBE-2010-3.5-03)
文摘In order to better understand the effects of biostimulation and bioaugmentation processes on a marine microbial community, three different mesocosm experiments were planned. Natural seawater（10.000 L） was artificially polluted with crude oil（1 L） and（1） inorganic nutrients（Biostimulating Mesocosm, BM）,（2） inorganic nutrients and an inoculum of Alcanivorax borkumensis SK2（Single Bioaugmentation Mesocosm, SBM）,（3） inorganic nutrients and inoculums of A. borkumensis SK2 and Thalassolituus oleivorans MIL-1（Consortium Bioaugmentation Mesocosm, CBM）. During the experimental period（20 days）, samples were taken from each mesocosm and the community structure was analyzed by PCR–DGGE. The 16 S r RNA gene DGGE banding patterns and sequence analysis demonstrated that biostimulation had the lowest effect on microbial biodiversity in the mesocosms; however, the biodiversity of the marine microbial community dramatically decreased in the CBM（Shannon index was 0.6 in T3）. The community structures among the three mesocosms were also markedly different,and major bacteria derived from DGGE bands were related to uncultured Gamma Proteobacteria. The biodegradation results show that the Single Bioaugmentation Mesocosm（SBM） system had the highest percentage of degradation（95%） in comparison to the BM mesocosm（80%） and CBM（70%）.
基金the award of Inspire Fellowship,Department of Science and Technology,New Delhi,India (No.IF110540)the award of UGCBSR Faculty Fellowship by the University Grants Commission,New Delhi,India
文摘Soil macroinvertebrates are highly diverse and their major ecological service include breakdown of organic matter and in turn improve soil fertility and pill-millipedes are well-known for their significant role in ingestion, disintegration and decomposition of organic matter in soil. This study characterized the feed, the decomposing leaf litter of coconut （Cocos nucifera）, and faeces of two endemic giant pill-millipedes Arthrosphaera disticta and A. fumosa collected from forests of the Western Ghats of India based on chemical features and microbial profile. In both millipedes, electric conductivity and total phosphorus were significantly increased in faeces, while the crude protein, organic carbon, total nitrogen and total phenolics were significantly decreased, as compared to those in feed. Heterotrophic bacteria, actinomycetes, rhizobia and phosphate-solubilizing bacteria were significantly higher in faeces than in feed, while filamentous fungi and yeast substantially decreased in faces compared to feed in both the millipedes. Spectrum of fatty acid methyl esters was considerably different between feed and faeces of both the millipedes. The total saturated fatty acids were higher than the total unsaturated fatty acids in feed as well as faeces, while the ratio of unsaturated/saturated fatty acids decreased from feed to faeces. Dodecanoic and tetradecanoic acids in A. disticta and octadecanoic acid in A. fumosa significantly increased, while （9Z）-octadec-9-enoic and （9E,12E）-octadeca-9,12-dienoic acids in A.. disticta and hexadecanoic, tetracosanoic and （9E,12E）- octadeca-9,12-dienoic acids in A. fumosa significantly decreased in faeces compared to feed, indicating millipede-dependent changes in fatty acids. Icosanoic acid was present in faeces of both the millipedes, and hexadec-9-enoic acid was confined to faeces of A disticta, while pentadecanoic, heneicosanoic, （9Z,12Z,15Z）-9,12,15-octadecatrienoic and eicosenoic acids were confined to faeces of A. fumosa. Pill-millipedes enrich the soil quality by leaf litter conditioning in their gut through specific microbial communities. Fingerprinting of fatty acid methyl esters in faeces of these millipedes reflected the activity of specific microbial population in their guts.
文摘The carbon cycle in shrimp polyculture mesocosm ecosystems was studied in the shrimp farm of the Huanghai Fisheries Group Corporation in Shandong Province from May to August, 1997. The results showed that the plankton community respiration rate fluctuated between 0.07 and 2.28 mgC/(L·d), average of 0.82±0.42 mgC/(L·d), which was 49 percent of the rate of phytoplankton gross production;that the average respiration rates (mgC/(L·d)) of micro , nano and pico plankton were 0.07, 0.38 and 0.31, which were 175, 30 and 207 percent of the corresponding sized phytoplankton production rates; that the sediment respiration rate (mgC/(m 2·d)) varied from 178.64 to 373.23, average of 262.60±48.68, and increased gradually with the lapse of culture time; and that the organic carbon accumulation and the respiration in the sediment of the shrimp monoculture mesocosm was higher than that in the polyculture mesocosms. The total sediment respiration per 25 m 2 mesocosm in the culture period averaged 571.16 gC, which was 10 percent of the total organic carbon input of the mesocosm.
文摘Indaziflam is a preemergent herbicide widely used for the control of weeds in pecan(Carya illinoinensis)orchards in the southwestern region of the United States.Given the paucity of data regarding the effect of indaziflam on the biochemical properties of soils supporting pecan production,this study was conducted to evaluate the effects of different application rates of indaziflam on soil microbial activity,diversity,and biochemical processes related to nitrogen(N)cycling.During two consecutive growing seasons(2015 and 2016),soil samples were obtained from experimental mesocosms consisting of soil-filled pots where pecan saplings were grown and treated with indaziflam applied at two different rates(25 and 50 g active ingredient(ai)ha^(-1),with the higher rate being slightly lower than the recommended field application rate of 73.1 g ai ha^(-1)).Soil samples were collected approximately one week before and one week after herbicide application for determination of soil microbial biomass and diversity,N mineralization,andβ-glucosaminidase activity.Soil samples collected from the control mesocosms without herbicide application were treated in the laboratory with two rates of indaziflam(75 and 150 g ai ha^(-1))to determine the immediate effect on microbial activity.No significant effect of herbicide treatment on soil respiration and microbial biomass was detected.The results showed a slight to moderate decrease in microbial diversity(7%in 2015 and 44%in 2016).However,decreasedβ-glucosaminidase activity with herbicide treatment was observed in soils from the mesocosms(33%)and soils treated with indaziflam in the laboratory(45%).The mineral N pool was generally dominated by ammonium after indaziflam application,which was consistent with the drastic decrease(75%)in nitrification activity measured in the laboratory experiment.The results of this study indicate that indaziflam,even when applied at higher than recommended rates,has limited effects on soil microbial activity,but may affect N cycling processes.
文摘Mesocosm hatcheries using semi-intensive culture methodologies are characterized by large tanks （40 m3） for fish larvae production at low densities （2-8 larvae/L）, with live prey production within the tank supplemented by exogenous sources of feed. Due to the high biological quality of larvae produced and low level of technological input, these methodologies are regarded as an interesting option to meet the increasing fry demand from the aquaculture industry. This study aimed to describe the experience at Centro de Maricultura da Calheta, Madeira Island, Portugal, with the establishment of a mesocosm hatchery for the production of marine fish larvae. Production trials were initiated with gilthead seabream Sparus aurata. This larval species presented faster growth in total body length （TL） per day （TL = 3.7516e~ ~293day, R2 = 0.9404）, higher survival rate （SR = 31.9%） and comparable swimbladder inflation rates （SB = 90%） to those of larvae reared with intensive methodologies. High larval performance was obtained with two candidate species for aquaculture： the red porgy Pagruspagrus （TL = 3.212e~~39day, R2 = 0.995; SR = 15.3%; SB = 95.7%） and the white seabream Diplodus sargus （TL = 3.6355e~~413day, R2= 0.9824; SR = 25%; SB --- 100%）. Testing ofa 110 m3 mesocosm rearing tank with white seabream larvae revealed limitations associated to larger tanks namely, the amount and quality of live feed required daily. First trials with striped jack （Pseudocararoc dentex） larvae resulted in low larval survival （0.04%）, but the use of a white tank avoided culture management constraints related to positive phototropism. The present results suggest that a mesocosm using semi-intensive methodologies may contribute to species diversification and consequently, to the sustainable development of aquaculture.
文摘In this paper, we constructed the halophyte Mesocosm experimental group which was used as a substrate material that consisted of tidal flat and dredged sediment. Depending on whether the ingredients of vegetation and substrate material of Mesocosm, we constructed Mesocosm A (tidal flat sediment + Salicornia herbecea), Mesocosm B (only dredged sediment), Mesocosm C (dredged sediment + Salicornia herbecea). Monitoring was carried out of seawater quality factors (Chemical Oxygen Demand (COD), Total Nitrogen (T-N), Total Phosphorus (T-P), temperature, salinity), sediment factors (Chemical Oxygen Demand (COD), Total (T-N), Total Phosphorus (T-P) and growth of Salricornia herbecea) in each Mesocosm. Habitat Stability Index of vegetation was calculating by using the monitoring results. HSI of Mesocosm C was calculated from 0.87 to 0.95 as compared to the relatively high HSI Mesocosm A, it was evaluated to be able to be used in the restoration of the coastal salt marsh with dredged sediment.
