Factors influencing biodeposit production by the New Zealand freshwater mussel Echyridella menziesii     

Kevin J. Collier  Susan J. Clearwater  Paula H. M. W. Neijenhuis  Susanna A. Wood 《新西兰海洋与淡水研究杂志》2018,52(1):1-15

Laboratory experiments on the New Zealand freshwater mussel Echyridella menziesii were used to investigate the short-term effects (7–8 days) of food type on rates of biodeposition and benthic substrate respiration. Post-feeding biodeposition rates ranged from 0.34 to 1.52?mg?g^?1?h^?1 (mean?=?0.50?mg g^?1?h^?1) and were unaffected by the addition of toxin-producing Microcystis. Addition of suspended sediment (30?mg?L^?1) visibly altered substrate composition, and increased total and inorganic biodeposit production rates by 24–33% compared to mussels fed commercial phytoplankton stock. Biodeposition rates of mussels in lake bed substrates were 38% higher than those in silica sand for identical feeding regimes, suggesting that a significant proportion of material produced in this experiment could have been derived from feeding on organic matter in the lake bed sediments. Respiration rates were higher in treatments with Microcystis but were unaffected by the presence of mussels. This laboratory study suggests that biodeposition by E. menziesii is resilient to short-term exposure to Microcystis, and highlights the ability of mussels to alter benthic substrate composition by incorporating suspended sediment into substrates.  相似文献   

ISOLATION, PURIFICATION AND CHARACTERIZATION OF THE HYDROGEN EVOLUTION PROMOTING FACTOR OF HYDROGENASE OF SPIRULINA PLATENSIS     

顾天青  张惠苗  孙世华 《中国海洋湖沼学报》1996,(1)

A component (s-factor) with obvious promoting effect on hydrogen evolution of hydrogenase has beenisolated and extracted from a Cell=free preparation of Spirulina platensis.The effect of the s-factor in the re-action system is similar to that of Na_2S_2O_4, but is coupled with ligh. The s-factor has the maximumabsorption peak at 620 nm in the oxidized state, at 590 nm in the reduced state. The partially purifieds-factor showed two bands by SDS-PAGE and is distinctly different from phycocyanin,which has nochange of oxidized state and reduced state absorption spectra, and also has no promoting effect onhydrogenase of Spirulina platensis under the light.  相似文献   

Trichodesmium erythraeum (Ehrenberg) bloom along the southwest coast of India (Arabian Sea) and its impact on trace metal concentrations in seawater     

Anoop A. Krishnan  P.K. Krishnakumar  M. Rajagopalan 《Estuarine, Coastal and Shelf Science》2007,71(3-4):641-646

The incidence of a large scale Trichodesmium erythraeum bloom along the southwest coast of India (Arabian Sea) observed in May 2005 is reported. Around 4802 filaments of T. erythraeum ml⁻¹ seawater was observed and a colony consisted of 3.6 × 10⁵ cells. The bloom was predominant off Suratkal (12° 59′N and 74° 31′E) with a depth of about 47 m, covering an area of 7 km in length and 2 km width. The concentrations of Zinc, Cadmium, Lead, Copper, Nickel and Cobalt were determined in samples collected from the bloom and non-bloom sites using stripping voltammetry. The observed hydrographical and meteorological parameters were found to be favorable for the bloom. The concentrations of Zinc, Cadmium and Nickel were found to be higher at bloom stations, while the concentrations of Lead, Copper and Cobalt were found to be very low at bloom stations. Elevated concentrations of Cadmium and Cobalt were observed at Valappad mainly due to the decomposition of detrital material produced in the bloom. Statistically significant differences (P > 0.01) in metal concentrations between the bloom and non-bloom stations were not observed except for Copper. Metals such as Lead, Copper and Cobalt were removed from the seawater at all places where bloom was observed. Cadmium was found to be slowly released during the decaying process of the bloom.  相似文献   

Consumption of bacteria by larvae of a deep-sea polychaete     

Adele J. Pile  & Craig M. Young 《Marine Ecology》2006,27(1):15-19

We investigated whether trochophore larvae of the polychaete Hesiocaeca methanicola, which lives on exposed ice‐like methane hydrates between 500 and 600 m, could consume near‐bottom picoplankton. In laboratory trials larvae significantly reduced the growth rates of all types of picoplankton, including heterotrophic bacteria, Prochlorococcus sp., Synechococcus‐type cyanobacteria and phototrophic eucaryotes <3 μm. Our findings suggest that these types of plankton may be important food sources for deep‐sea planktotrophic larvae.  相似文献   

Microbial Biomass Dynamics Along a Trophic Gradient at the Atlantic Barrier Reef off Belize (Central America)   总被引：2，自引：0，他引：2  

Gerhard J.  Herndl 《Marine Ecology》1991,12(1):41-51

Abstract. Recent findings indicate that heterotrophic bacteria and not phytoplankton are the most numerous biomass components even in the euphotic zone of oligotrophic, open oceans. In this study it was hypothesized that the microbial biomass components change within a few hundred meters as oligotrophic water flows across the reef and becomes enriched with nutrients. Along a trophic gradient, four stations at the Atlantic Barrier Reef off Belize (Central America) were sampled for microbial biomass components. Phytoplankton biomass (measured as chlorophyll a) ranged from the most oligotrophic station (St. 1) to the most eutrophic station (St. 4) from 6.9–415.5 μg CI"' (assuming a C:chl a ratio of 30): heterotrophic bacterial biomass increased 4-fold (from 10.1–46.4μg C 1^-1), heterotrophic nanoflagellate (HNAN) biomass increased from 4.6-19ug C 1^-1, and cyanobacteria from 0.9-4.5 μg C-1^-1. Production estimates derived from seawater cultures revealed a 5-fold increase in bacterial production from the oligotrophic station (3.7 ug C 1^-1 d^-1) to the eutrophic St. 4 (17.8ug C-1-d1^-1)- Cyanobacterial production rose from 1.1–3.5ug C-1–d^-1 and HNAN production from 0.65-1.13 μg C-1^-1 -d^-1. While cyanobacteria contributed between 13 and 20% to the autotrophic plankton component in the oligotrophic waters, their contribution dropped to about 1 % at the eutrophic stations.  相似文献   

Short-term consequences of a benthic cyanobacterial bloom (Lyngbya majuscula Gomont) for fish and penaeid prawns in Moreton Bay (Queensland, Australia)     

S.J. Pittman  K.M. Pittman 《Estuarine, Coastal and Shelf Science》2005,63(4):619-632

This study examined the phenology and ecological consequences of a benthic filamentous cyanobacterial bloom (Lyngbya majuscula) in Deception Bay (Moreton Bay, Queensland, Australia). Bloom initiation occurred in mid December 1999 and expanded to encompass an 8 km² area by April 2000. Small fish and penaeid prawns (<25 cm total length) were quantitatively sampled through periods designated as before, during and after the bloom using a combination of pop-netting within mangroves and beam trawling over adjacent seagrass beds. Data on larger-bodied fish were compiled from daily fishing logs provided by local commercial fishers. Changes in dry mass of bloom material caught in nets and changes in water chemistry were also measured. Mean concentrations of ammonia-N in residual water within mangroves were several orders of magnitude higher in the affected area than in the control and dissolved oxygen was markedly lower in affected areas. Across the study area, mean density, live mass and number of species declined during the bloom, with fish assemblages using mangroves showing greater decline than assemblages using seagrasses. Response at the species level was highly variable; generally, epibenthic species showed a more sustained decline than demersals. Mean monthly fish catch was significantly lower in bloom than non-bloom years. This study has also demonstrated that throughout the bloom, the affected area continued to support a highly diverse and abundant fish and prawn assemblage, and probably maintained its function as an important nursery habitat for many species.  相似文献   

Microcoleus autumnalis and filamentous algae-dominated mats and chlorophyll-a increase with agricultural land use but respond differently to associated nutrient and sediment enrichment     

Susanna A. Wood  Annika Wagenhoff  Logan Brown  Javier Atalah 《新西兰海洋与淡水研究杂志》2020,54(3):449-466

ABSTRACT

This study investigated the impact of pastoral land use and nutrient and fine sediment inputs on Microcoleus autumnalis and filamentous algae-dominated mats, and benthic chlorophyll-a in streams (lower North Island, New Zealand). Surveying and sampling was undertaken monthly at 61 sites spanning a wide gradient in catchment cover and environmental conditions. Two boosted regression tree models were built. The first models included pastoral land cover and five environmental variables as predictors. In the second model pastoral land cover was replaced by nutrient/sediment data. The abundance of the two mat types and chlorophyll-a increased when pastoral land cover was between 20% and 70% (model 1). Replacement of pastoral land cover by nutrient/sediment data (model 2) slightly improved the model fit for all three periphyton variables. Microcoleus autumnalis-dominant mats increased with dissolved inorganic nitrogen concentrations up to ca. 0.6?mg?L^?1, and in streams with more frequent flushes. In contrast, filamentous algal-dominated mats increased with turbidity, and in streams with less frequent flushes. Chlorophyll-a generally followed the response of the dominant periphyton type. Increased knowledge on responses of specific periphyton types, rather than total biomass, to environmental variables is essential to guide effective management strategies.  相似文献   

Laboratory Culture and Preliminary Characterization of the Nitrogen-Fixing Rhizosolenia-Richelia Symbiosis     

Tracy A.  Villareal 《Marine Ecology》1990,11(2):117-132

Abstract. The oceanic diatom Rhizosolenia clevei and its cyanobactcrial symbiont Richelia intracel-luluris were isolated into laboratory culture and their biology and growth dynamics examined. Nitrogen-fixation by the symbiont could sustain the symbiosis. Growth and nitrogenase activity demonstrated light saturation kinetics, with no photoinhibition up to 315 μE m^-1 s^-1 for growth and 780μE m^-1 s^-1 for nitrogen fixation. The symbiosis is not obligate for Rhizosolenia , which is capable of growth independent of the symbiont if a nitrogen source is available. The symbiont is contained in the pcriplasmic space between the Rhizosolenia plasmalcmma and frustulc, and preliminary evidence suggests excretion of fixed nitrogen into the medium may be occurring.  相似文献   

Real eukaryotes and precipitates first found in the Middle Riphean stratotype, southern Urals   总被引：1，自引：0，他引：1  

V. N. Sergeev  Lee Seong-Joo 《Stratigraphy and Geological Correlation》2006,14(1):1-18

  相似文献   

两个相连湖泊的微生态系统——云南高原湖泊中浅水的星云湖和深水的抚仙湖研究   总被引：4，自引：0，他引：4  

大久保贤治  熊谷道夫  坂本充  宋学良  张子雄 《云南地理环境研究》2002,14(2):10-19

抚仙湖是中国云南省的一个深水湖，连接着富营养化的浅水湖－－星云湖，星云湖排放含绿藻的水进入抚仙湖。两湖位于省会昆明附近，由于地方文化、集约化农业、以及旅游业的发展，两湖已经富营养化。因为湖泊体积容量的级别差异，深水湖的富营养化几乎没被注意，抚仙湖秋季下层滞水带缺氧已经关注了20年，似乎下层滞水带是深水湖富营养化的指标或趋势。抚仙湖看起来目前情况尚好，可以说寡营养，然而，外界负荷是潜在的，且是以稳定的加速度进行的。在此对浅水湖富营养化的原因进行了讨论，包括在其它云南湖泊观察到富营养化的过程，再者，对两个连相湖的藻和蓝藻碎片的大小构成进行比照。为了与深水的抚仙湖状况进行比较，简略介绍了一个日本的深湖及其径流系统。其中，涡流和它的微生态系统，在两者中相关性很好。对于以涡流生态系统的见解判断微生态系统的深水湖富营养化问题将给予概括。  相似文献