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1.
Year-round investigations were carried out to address the population dynamics of amphipod Ampithoe valida and its potential regulating factors in the Yundang Lagoon (a eutrophic subtropical coastal lagoon in Xiamen City, China) from October 2007 to October 2008. The results show that A. valida population was largely composed of juveniles and reached a peak abundance (12.02 × 10 3 ind./m2 ) in March, but sharply shrunk in July. The monthly variation pattern of A. valida seemed to follow that of Ulva lactuca which is the main food resource for A. valida, indicating a strong influence of food availability on A. valida population dynamics. Life cycle studies in laboratory indicate that A. valida adopted an r-selected life strategy, e.g., rapid growth rate (0.216-0.302 mm/d), consecutive breeding (4-10 times), short reproductive rhythm (9-17 d) and huge fecundity (24-192 eggs or 6-94 juveniles per brood), which contributed to the fast population growth of A. valida from January to March. Although temperature may also be a significant cause, A. valida could grow quickly and show normal reproductive traits (i.e., the timing of sexual differentiation or maturity, the reproductive rhythm, the number of broods all through its lifespan and offspring production) in temperature between 15-30 C. Therefore, the temperature variation in the lagoon water should not account for the sharp variation of A. valida population by affecting the survival, growth and reproduction of the amphipod. However, negative correlation between water temperature and U. lactuca biomass in the lagoon suggested that temperature could have indirectly affected the population dynamics of A. valida by affecting its food availability. The authors conclude that, in the Yundang Lagoon, the population dynamics of A. valida was mainly controlled by the food availability rather than water temperature. 相似文献
2.
Grazing impact of microzooplankton on phytoplankton in the Xiamen Bay using pigment-specific dilution technique 总被引：2，自引：0，他引：2
HUANG Bangqin LIU Yuan XIANG Weiguo TIAN Haojie LIU Hongbin CAO Zhenrui HONG Huasheng 《海洋学报(英文版)》2008,27(5):147-162
Phytoplankton group-specific growth and microzooplankton grazing were determined seasonally using the dilution technique with high-performance liquid chromatography （HPLC） in the Xiamen Bay, a subtropical bay in southeast China, between May 2003 and February 2004. The results showed that growth rates of phytoplankton ranged from 0.71 to 2.2 d^-1 with the highest value occurred in the inner bay in May. Mierozooplankton grazing rates ranged from 0.5 to 3.1 d^-1 with the highest value occurred in the inner bay in August. Microzooplankton grazing impact ranged from 39% to 95% on total phytoplankton Chl a biomass, and 65% to 181% on primary production. The growth and grazing rates of each phytoplankton group varied, the highest growth rate （up to 3.3 d^-1 ） was recorded for diatoms in August, while the maximum grazing rate （ up to 2.1 d ^-1 ） was recorded for chlorophytes in February in the inner bay. Among main phytoplankton groups, grazing pressure of microzooplankton ranged from 10% to 83% on Chl a biomass, and from 14% to 151% on primary production. The highest grazing pressure on biomass was observed for cryptophytes （83%） in August, while the maximum grazing pressure on primary production was observed for eyanobacteria （up to 151% ） in December in the inner bay. Net growth rates of larger phytoplanktons （diatoms and dinoflagellates） were higher than those of smaller groups （ prasinophytes, chlorophytes and cyanobacteria）. Relative preference index showed that microzooplankton grazed preferentially on prasinophytes and avoided to harvest diatoms in cold seasons （December and February）. 相似文献
3.
Growth and energy budget of marine amphipod juvenile Eogammarus possjeticus at different temperatures(20°C,24°C, 26°C, 28°C, 30°C, 32°C and 34°C) were investigated in this study. The results showed that the cumulative mortality rate increased significantly with rising temperature(p0.01), and exceeded 50% after 24 h when temperature was above 30°C. With the temperature increasing from 20°C to 26°C, the ingestion rate and absorption rate increased, but decreased significantly above 28°C(p0.01), indicating a decline in feeding ability at high temperatures. The specific growth rate increased with rising temperature, but decreased significantly(p0.01) after reaching the maximum value at 24°C. Similarly, the oxygen consumption and ammonia emission rates also showed a trend of first increase and then decrease. However, the O:N ratio decreased first and then increased with rising temperature, indicating that the energy demand of E. possjeticus juvenile transferred from metabolism of carbohydrate and lipid to protein. In the energy distribution of amphipods, the proportion of each energy is different. With rising temperature, the ratio of the energy deposited for growth accounted for ingested gross energy showing a trend of decrease, while the energy lost to respiration, ammonia excretion, and feces accounted for ingested gross energy being showed a trend of increase. It seemed that rising temperature increased the metabolism and energy consumption of the amphipods and, meanwhile, decreased the energy used for growth, which may be an important reason for the slow growth and small body size of the amphipods during the summer high-temperature period. 相似文献
4.
A study was carried out to investigate the grazing pressure of heterotrophic nanoflagellates(HNF) on bacteria assemblages in the Yellow Sea Cold Water Mass(YSCWM) area in October, 2006. The results show that the HNF abundance ranges from 303 to 1 388 mL-1, with a mean of 884 mL-1. The HNF biomass is equivalent to 10.6%–115.6% of that of the bacteria. The maximum abundance of the HNF generally occurred in the upper 30 m water layer, with a vertical distribution pattern of surface layer abundance greater than middle layer abundance, then bottom layer abundance. The hydrological data show that the YSCWM is located in the northeastern part of the study area, typically 40 m beneath the surface. A weak correlation is found between the abundances of HNF and bacteria in both the YSCWM and its above water layer. One-way ANOVA analysis reveals that the abundance of HNF and bacteria differs between inside the YSCWM and in the above water mass. The ingestion rates of the HNF on bacteria was 8.02±3.43 h-1 in average. The grazing rate only represented 22.75%±6.91% of bacterial biomass or 6.55%+4.24% of bacterial production, implying that the HNF grazing was not the major factor contributing to the bacterial loss in the YSCWM areas. 相似文献
5.
Marcelino Ruiz-Domínguez Casimiro Qui?onez-Velázquez Dana Isela Arizmendi-Rodriguez Víctor Manuel Gómez-Mu?oz Manuel Otilio Nevárez-Martínez 《海洋学报(英文版)》2021,40(9):53-65
In recent years, the small pelagic fishery on the Pacific northwest coast of Mexico has significantly increased fishing pressure on thread herring Opisthonema spp. This fishery is regulated using a precautionary approach(acceptable biological catch(ABC) and minimum catch size). However, due to fishing dynamics, fish aggregation habits and increased fishing mortality, periodic biomass assessments are necessary to estimate ABC and assess the resource status. The Catch-MSY approach was used to analyze historical series of thread herring catches off the western Baja California Sur(BCS, 1981–2018) and the Gulf of California(GC, 1972–2018) to estimate exploitable biomass and target reference points in order to obtain catch quotas. According to the results, in GC,the maximum biomass reached in 1972(at the beginning of fishery) and minimum biomass reached in 2015; the estimated exploitable biomass for 2019 was 42.2×10~4 t; and the maximum sustainable yield(MSY) was 15.4×10~4 t.In the western BCS coast, the maximum biomass was reached in 1981(at the beginning of fishery) and minimum biomass was reached in 2017; the estimated exploitable biomass for 2019 was 3.2×10~4 t; and the MSY was 1.2×10~4 t.Both stocks showed a decrease in biomass over the past years and were currently near to point of full exploitation.The results suggest that the use of the Catch-MSY method is suitable to obtain annual biomass estimates, in order to establish an ABC, to know the current state of the resource, and to avoid overcoming the potential recovery of the stocks. 相似文献
6.
-Marine chroococcoid phycoerythrin - containing Synechococcus spp. recently have been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although the importance of Synechococcus as food sources for heterotrophic nanoplankton are now recognized, the information about its cycling of biomass and diel patterns is limited and the methodology used varies according to different authors. A selective metabolic inhibitor method was used to allow simultanous estimation of both growth rates and grazing disappearance rates of Synechococcus. Results obtained in the English Channel show growth rates ranging from 0. 25 to 0. 72 d-1 with an average value of 0. 51 d -1and grazing disappearance rates ranged from 0. 21 to 0. 64 d-1 (mean = 0. 44 d-1). Offshore in the Celtic Sea of the Northeast Atlantic Ocean, both rates were lower than in the channel. The similarity between average growth and grazing rates suggests a rapid recycling of Synechococcus biomass. In diel pattern, Synechococc 相似文献
7.
The standing crop and primary production of benthic microalgae on tidal flats have seasonally been observed in the Sanggou and Jiaozhou Bays of the northern China coast during 1999 - 2000. The results show that the annual primary productions of benthic microalgae on tidal flats in the two bays are 2 532 and 7 542 tons carbon, which would be able to support 3.1 x 103 and 9.2 x 103 tons shellfish meat, respectively. The nature of sediment is essential for governing the biomass and primary production of benthic microalgae on tidal flats. The biomass and primary production of benthic microalgae on tidal flats with muddy sediments are higher than those with sandy sediments, which resulted from higher nutrient concentration and lower grazing pressure. That is the reason why in comparison with Xiangshan Bay the standing crop and production of benthic microalgae on tidal flats of the Sanggou and Jiaozhou Bays are low. Light was a key factor controlling vertical distribution of biomass and production of benthic 相似文献
8.
《Journal of Oceanography》2007,63(6):983-994
A mesoscale iron-enrichment study (SEEDS II) was carried out in the western subarctic Pacific in the summer of 2004. The iron
patch was traced for 26 days, which included observations of the development and the decline of the bloom by mapping with
sulfur hexafluoride. The experiment was conducted at almost the same location and the same season as SEEDS (previous iron-enrichment
experiment). However, the results were very different between SEEDS and SEEDS II. A high accumulation of phytoplankton biomass
(∼18 mg chl m−3) was characteristic of SEEDS. In contrast, in SEEDS II, the surface chlorophyll-a accumulation was lower, 0.8 to 2.48 mg m−3, with no prominent diatom bloom. Photosynthetic competence in terms of F
v/F
m for the total phytoplankton community in the surface waters increased after the iron enrichments and returned to the ambient
level by day 20. These results suggest that the photosynthetic physiology of the phytoplankton assemblage was improved by
the iron enrichments and returned to an iron-stressed condition during the declining phase of the bloom. Pico-phytoplankton
(<2 μm) became dominant in the chlorophyll-a size distribution after the bloom. We observed a nitrate drawdown of 3.8 μM in the patch (day 21), but there was no difference in silicic acid concentration between inside and outside the patch. Mesozooplankton
(copepod) biomass was three to five times higher during the bloom-development phase in SEEDS II than in SEEDS. The copepod
biomass increased exponentially. The grazing rate estimation indicates that the copepod grazing prevented the formation of
an extensive diatom bloom, which was observed in SEEDS, and led to the change to a pico-phytoplankton dominated community
towards the end of the experiment. 相似文献
9.
The production of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) by marine microalgae was investigated to elucidate more on the role of marine phytoplankton in ocean-atmosphere interactions in the global biogeochemical sulfur cycle.Axenic laboratory cultures of four marine microalgae–Isochrysis galbana 8701,Pavlova viridis,Platymonas sp.and Chlorella were tested for DMSP production and conversion into DMS.Among these four microalgae,Isochrysis galbana 8701 and Pavlova viridis are two species of Haptophyta,while Chlorella and Platymonas sp.belong to Chlorophyta.The results demonstrate that the four algae can produce various amounts of DMS(P),and their DMS(P) production was species specific.With similar cell size,more DMS was released by Haptophyta than that by Chlorophyta.DMS and dissolved DMSP (DMSPd) concentrations in algal cultures varied significantly during their life cycles.The highest release of DMS appeared in the senescent period for all the four algae.Variations in DMSP concentrations were in strong compliance with variations in algal cell densities during the growing period.A highly significant correlation was observed between the DMS and DMSPd concentrations in algal cultures,and there was a time lag for the variation trend of the DMS concentrations as compared with that of the DMSPd.The consistency of variation patterns of DMS and DMSPd implies that the DMSPd produced by phytoplankton cells has a marked effect on the production of DMS.In the present study,the authors’ results specify the significant contribution of the marine phytoplankton to DMS(P) production and the importance of biological control of DMS concentrations in oceanic water. 相似文献
10.
《中国海洋工程》1990,(2)
Most of reservoirs explorated offshore China are of medium and small size considered as marginal fields. Economic analysis of fields development shows that the conventional floating production system is still too expensive to be taken for the small sized reservoirs. It is necessary to develop a new concept of early production system. SOECO has developed a new production platform which is called formally Semisubmersible Anti-Typhoon Production Storage and Mooring - SAPSM. Both the theoretic study and model test have proved that the new platform is a suitable early production system for developing oil reserves offshore China and has the ability to survive in typhoon. 相似文献
11.
12.
通过在高度富营养化的海水泻湖——厦门贸彗湖开展龙须菜（Gracilaria lemaneiformis）的延绳夹苗挂养与网笼挂养实验和室内端足类啃食海藻实验，探讨了影响筼筜湖龙须菜生长的主要因素。结果显示，筼筜湖龙须菜的表观生长率为0．42％／d，实际生长率为4．80％／d，强壮藻钩虾（Ampithoe valida）的摄食量占龙须菜总生长量的91．4％。而且，筼筜湖的水流缓慢，使藻体附着最高可达2．32g／gFw的颗粒物，明显抑制了龙须菜的生长。以上研究表明，端足类的啃食作用和不良的水动力条件是导致筼筜湖龙须菜表观生长率低的主要原因。 相似文献
13.
The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. 15N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen. 相似文献
14.
Enrichments with five types of organic carbon, differing in nitrogen content and type of organic carbon, were made to a marine sediment in order to study effects on nitrogen fluxes. The enrichments used were Ulva lactuca, Ascophyllum nodosum, Zostera marina, Ceratium spp., lignin, and mixtures of U. lactuca and A. nodosum. Fluxes of ammonium, nitrate, and phosphate were measured in short-term (48 h) microcosm experiments, using a carbon enrichment loading similar to that at the sampling site. Changes in microbial community growth and structure due to three types enrichments were also detected using molecular methods in a microcosm experiment run for 4 days to allow for detection at DNA-level.Ammonium fluxes changed from an efflux in the control to an influx for all enrichments apart from U. lactuca. The change was significantly related to the added material's C:N ratio when Ceratium spp. was excluded. All enrichments induced an influx of nitrate suggesting the formation of anoxic micro zones, but there was no relationship with C:N ratio. Instead, the magnitude of the nitrate influx is suggested to be related to the structure of the organic carbon, where enrichments containing a large pool of cellulose and lignin (Z. marina and lignin) gave rise to a lower influx, compared to algal material with more easily degraded organic matter like lipids and starch, which induced the highest influx of nitrate (Ceratium spp., U. lactuca, and A. nodosum). The occurrence of an ammonium influx together with increased nitrate influx and a lower efflux of phosphate in the enrichments suggests a growth of heterotrophic bacteria. This was also confirmed using molecular methods (PCR-DGGE) where the relative abundance of bacterial species in the enrichments increased.The sum of ammonium and nitrate fluxes showed that total nitrogen removal was enhanced in all enrichments compared to the nonenriched control sediment, but in different ways. Ceratium spp. induced the highest removal followed by A. nodosum, U. lactuca, Z. marina, and lastly, by lignin. The same pattern was observed also in a second experiment. These results indicate that easily degradable organic carbon, together with a lower C:N ratio of the added material, will remove nitrogen from the water phase, making the recycling of nitrogen to the overlying water mass smaller. 相似文献
15.
近年来，海水富营养化导致近海海域大型海藻过量繁殖，成为世界性的环境问题。自2007年以来，浒苔绿潮在黄海海域连续暴发，造成巨大经济损失。为探究浒苔大规模暴发与氮磷比值(N/P)的关系，及其与其他大型绿藻在不同N/P下的竞争机制，研究了浒苔(Ulva prolifera)与石莼(Ulva lactuca)在不同N/P下单独培养和共培养时的生长情况，探究了浒苔及石莼生长的变化；结合苏北浅滩海域现场N/P的调查结果，分析了浒苔绿潮暴发的可能机制。研究结果表明:(1)浒苔单独培养时，在一定范围内高N/P能促进浒苔的生长，氮对于浒苔的影响大于磷。(2)石莼单独培养时，低N/P下石莼长势最好，但改变N/P对石莼的影响并不显著。(3)浒苔和石莼共培养时，浒苔生长受到了一定限制，低N/P下浒苔生长受限更显著。(4)苏北浅滩海域高N/P更适合浒苔的生长，可能是浒苔绿潮能够大规模暴发的原因之一。 相似文献
16.
采用生理生态学方法,研究了中华原钩虾(Eogammaruspossjeticus)对黄海绿潮原因种浒苔(Ulva prolifera)及海水池塘4种优势大型海藻,即肠浒苔(Ulva intestinalis)、扁浒苔(Ulva compressa)、线形硬毛藻(Chaetomorphalinum)和丝毛藻(Cloniophorasp.)的摄食率,比较了对浒苔与其他不同类型饵料(包括人工饵料)的摄食,开展了不同密度的中华原钩虾对浒苔的现场摄食研究。结果显示,中华原钩虾的摄食率、饵料吸收率与海藻的含水量成呈正相关,表明该端足类存在明显的补偿性摄食行为。对不同类型饵料的摄食结果显示,中华原钩虾除了摄食海藻,对豆粕、虾饲料等人工饵料也具有较高的饵料吸收率,表明其可人工投喂培育。中华原钩虾具有一定摄食节律,夜晚摄食量高于白昼,表明夜晚投喂有利于中华原钩虾摄食,可减少饵料污染,有利于清洁生产。现场摄食实验结果显示,中华原钩虾摄食量随养殖密度的增加而增加,但其摄食率和存活率与养殖密度呈负相关,表明高密度时中华原钩虾竞争摄食增加了饵料消耗,同时中华原钩虾为抵抗养殖密度过高造成的竞争而增加能量等消耗。 相似文献
17.
A mechanism of competition between epiphytes and seagrasses potentially modulated by grazers was studied in a high-nutrient Thalassia testudinum meadow in the Indian River Lagoon (Florida, U.S.A.). The effects of fish grazing on epiphytes, and likely enhancing T. testudinum growth, was tested through an exclusion experiment. Twelve (2×2m) independent experimental plots were selected within a shallow monospecific bed to which three randomized treatments (exclusion fences, open fences and controls) with four replicates each were assigned. The epiphyte load was monitored on T. testudinum leaves inside the plots from January 1995 to March 1996. Treatment effects occurred during a chlorophyte bloom in March 1995, when the epiphyte biomass was significantly higher inside the exclusion cages than in either of the controls. The composition of the epiphytic community in March 1995 was dominated by sheet-like Enteromorpha and filamentous algae such as Cladophora , which are less resistant to herbivory than the coarsely-branched forms of red algae (e.g. Hypnea , Chondria and Acanthophora) that bloomed subsequently. These results suggest that herbivory change seasonally depending on the availability of different prey species to fish-grazers, which preferentially utilize the fleshy green algae typical of bloom conditions over the thicker coarsely-branched red algae. In the nutrient-rich lagoon the role of top-down interactions in enhancing T. testudinum growth is limited to the reduction of shading by green macroalgae. 相似文献
18.
Melanie Gammon Andrew Turner Murray T. Brown 《Estuarine, Coastal and Shelf Science》2009,84(4):447-452
The short-term (5 day) accumulation of Cu and Zn in different tissues of the marine gastropod, Littorina littorea, has been studied in the presence of 10 mg l−1 of antifouling paint particles and pre- or simultaneously contaminated algal food (Ulva lactuca). Accumulation of Cu was observed in the head–foot, digestive gland–gonad complex and gills to extents dependent on how and when food was contaminated and administered. However, retention of Zn was only observed in the gills and only when L. littorea and U. lactuca were simultaneously exposed to paint particles. Relative to the alga, faecal material was highly enriched in Zn, suggesting that the animal is able to rapidly eliminate this metal, most likely through the formation and egestion of insoluble phosphate granules. Thus, L. littorea is a useful biomonitor of marine contamination by antifouling applications in respect of Cu but not Zn. 相似文献
19.
Green tides caused by the unusual accumulation of high floating Ulva prolifera have occurred regularly in the Yellow Sea since 2007. The primary source of the Yellow Sea green tides is the attached algae on the Pyropia aquaculture rafts in the Subei Shoal. Ulva prolifera and Blidingia(Italic) sp. are the main species observed on Pyropia aquaculture rafts in the Subei Shoal. We found that U. prolifera has strong buoyancy and a rapid growth rate, which may explain why it is the dominant species of green tides that occur in the China's sea area of the Yellow Sea. The growth rate of floating U. prolifera was about 20%–31% d–1, which was much higher than Blidingia(Italic) sp. There were about 1.7 × 10~4 t of attached algae on the Pyropia aquaculture rafts in May 2012. We found that 39% of attached algae could float when the tide rose in the Subei Shoal, and U. prolifera accounted for 63% of the floating algae. Our analysis estimated that about 4 000 t of attached U. prolifera floated into the surrounding waters of the Subei Shoal during the recycling period of aquaculture rafts. These results suggest that the initial floating biomass of large-scale green tides in the Yellow Sea is determined by the U. prolifera biomass attached to Pyropia aquaculture rafts, further impacting the scale of the green tide. 相似文献