A Survey of Estuarine Benthic, Zoo-planktonic and Phytoplanktonic Communities of Amvrakikos Gulf, Ionian Sea     

A. Nicolaidou    M. Moraitou-Apostolopoulou  L. Ignatiades 《Marine Ecology》1983,4(3):197-209

Abstract. The estuarine ecosystem of the Amvrakikos Gulf, a semi-enclosed embayment of the Ionian Sea, was surveyed at 9 stations in June, 1980. Quantitative and qualitative relationships among the phytoplanktonic, zooplanktonic and benthic populations were examined and related to environmental parameters. It was found that quantitative maxima of each of the three components occurred at different stations. When stations were grouped according to a similarity index of each community, it could be shown that the stations were very similar with regard to phytoplankton and slightly less similar with regard to zooplankton. The stations differed considerably as far as the benthos is concerned. The phytoplankton also exhibited a lower species diversity (0.08-0.82 bits-indiv.^-1) than the zooplankton (1.08-2.10 bits indiv.^-1) and the benthos (0.85-5.06 bits indiv.^-1). Differences in salinity among stations showed no significant correlation with the abundance or species diversity of phytoplankton, zooplankton or benthos.  相似文献   

Temporal changes of accretion rates on an estuarine salt marsh during the late Holocene — Reflection of local sea level changes? The Wadden Sea, Denmark     

A.T. Madsen  A.S. Murray  M. Pejrup 《Marine Geology》2007,242(4):221-233

The temporal variability of estuarine sedimentation has been investigated in the northernmost part of the Wadden Sea (Denmark), using an estuarine sedimentary sequence at Ho Havn. The sedimentary sequence appears to have been deposited within the last ∼ 2000 yr based on detailed luminescence dating of the estuarine mud, whose ages range between 225 ± 40 and 2050 ± 300 yr. The age-depth profile reveals that the sedimentation rate has varied considerably in the past. Estuarine sedimentation was very rapid ∼ 1400 yr ago; the ages over almost 1 m of sediment are indistinguishable. After this accretion rate of ∼ 9 mm a^− 1, the rate dropped abruptly to ∼ 0.3 mm a^− 1 some time between 1340 and 970 yr ago. This slow rate of accretion continued until ∼ 350 yr ago, when it accelerated to ∼ 1.3 mm a^− 1. These abrupt changes in the accretion rate are possibly related to local sea level fluctuations, thus the period with low accretion rate most probably reflects a situation with a stable or decreasing relative sea level. The rapid deposition of ∼ 0.9 m of sediment within about one century some 1400 yr ago shows that large amounts of fine-grained sediment were available for deposition in the region at that time, and an increasing relative sea level was most probably responsible for the creation of the accommodation space for sedimentation. Recent studies on mudflats and salt marshes in the region also tend to show high accretion rates, indicating that the coastal lagoons could be less vulnerable and threatened by a future sea level rise than generally believed.  相似文献   

Photobleaching of fluorescence and the organic carbon concentration in a coastal environment     

Annelie Skoog  Margareta Wedborg  Elisabet Fogelqvist 《Marine Chemistry》1996,55(3-4)

In order to investigate the photobleaching potential of estuarine waters from different depths and redox conditions and with varying degree of biological activity, filtered, unfiltered and chloroform-poisoned water samples from the Baltic Sea were exposed to ambient sunlight. Fluorescence, at excitation 350 nm and emission 450 nm, was used as an indication of humic substance concentration. Fluorescence and organic carbon concentration were measured at regular time intervals during light exposure. We found that the decrease in humic substance fluorescence can be fitted to an exponential decay function. The fluorescence half-lives were within the range 0.4 – 4.6 days in different water masses, with fluorescence decreasing to between 20% and 60% of initial concentration, respectively. Results from the curve fitting procedure indicate a rest concentration of humic substance fluorescence, similar among the sampled sites, that is resistant to further photochemical degradation. The largest relative decreases in fluorescence were found in deep waters, but samples from deep waters also had a higher fluorescence rest concentration than samples from surface waters. Biological activity was reduced by filtering the samples through 0.2μm pore size filters or adding chloroform. No statistically significant differences were found after 3 days of irradiation between samples with and without treatment to reduce biological activity. The highest initial fluorescence values and the largest fluorescence decrease were found in the anoxic waters of the Gotland Deep. The organic carbon concentrations decreased 3–7% at all stations. The shortest half-life of humic substance, and the largest decrease in organic carbon concentrations, were found in samples from the northern basins of the Baltic Sea.  相似文献   

A Review of Studies on the Interaction Between Waves and Muddy Bottom     

Zhao Zidan Professor  Doctoral Supervisor  Tianjin University  Tianjin 《中国海洋工程》1992,(2)

This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University.  相似文献   

Benthic macrofauna–habitat associations in Willapa Bay, Washington, USA   总被引：1，自引：0，他引：1  

Steven P. Ferraro  Faith A. Cole 《Estuarine, Coastal and Shelf Science》2007,71(3-4):491-507

Estuary-wide benthic macrofauna–habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [Crassostrea gigas], bare mud/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants, a fanworm, Manayunkia aestuarina, in Spartina, and a sand dollar, Dendraster excentricus, in subtidal, were rare or absent in all other habitats. Benthic macrofaunal Bray–Curtis similarity varied among all habitats except eelgrass and oyster. There were significant differences among habitats within- and between-years on several of the following ecological indicators: mean number of species (S), abundance (A), biomass (B), abundance of deposit (AD), suspension (AS), and facultative (AF) feeders, Swartz's index (SI), Brillouin's index (H), and jackknife estimates of habitat species richness (HSR). In the 4 habitats sampled in both years, A was about 2.5× greater in 1996 (a La Niña year) than 1998 (a strong El Niño year) yet relative values of S, A, B, AD, AS, SI, and H among the habitats were not significantly different, indicating strong benthic macrofauna–habitat associations despite considerable climatic and environmental variability. In general, the rank order of habitats on indicators associated with high diversity and productivity (high S, A, B, SI, H, HSR) was eelgrass = oyster ≥ Atlantic cordgrass ≥ mud shrimp ≥ bare mud/sand ≥ ghost shrimp = subtidal. Vegetation, burrowing shrimp, and oyster density and sediment %silt + clay and %total organic carbon were generally poor, temporally inconsistent predictors of ecological indicator variability within habitats. The benthic macrofauna–habitat associations in this study can be used to help identify critical habitats, prioritize habitats for environmental protection, index habitat suitability, assess habitat equivalency, and as habitat value criteria in ecological risk assessments in Willapa Bay.  相似文献   

磨刀门河口近期演变及其排洪效应   总被引：3，自引：0，他引：3  

王世俊  胡达  李春初 《海洋通报》2006,25(2):21-26

通过分析珠江磨刀门分流河口水动力结构及拦门沙的走向变化,解析磨刀门河口近期演变,并从河口的结构和功能的角度,分析磨刀门河口的排洪功能和行为。结论认为:(1)磨刀门河口正由径流优势型向河流—波浪型转变,波浪成为改造和修饰口门地形的重要动力;(2)磨刀门河口的动力、地貌变化,使得河口对淡水的防御性增强而渗透性减弱,其排洪潜力有限;(3)强径流河口发育支汊是河口延伸中的基本规律,在今后磨刀门的治理开发过程(尤其是排洪)中应注意支汊的保护利用。  相似文献   

黄河口及渤海中南部沉积特征变化及其环境动力分析   总被引：3，自引：0，他引：3  

吕丹梅  李元洁 《中国海洋大学学报(自然科学版)》2004,34(1):133-138

渤海中南部沉积类型及其分布受海底地形、水动力条件和物质来源影响 ,具有明显的分区多样性。而黄河巨大的输沙量进入渤海南部 ,其运移和扩散对这一地区沉积物的分布产生很大的影响。本文通过对不同时期底质情况的对比 ,说明研究区海底沉积的分布格局受到黄河河口不断向海延伸的影响在最近十几年中发生了很大的变化。而河口区的底质分布还受到最近几年黄河断流 ,水沙来量减少的深刻影响。  相似文献   

河口最大浑浊带形成的动力模式和数值试验   总被引：8，自引：0，他引：8  

朱建荣  傅德健吴辉 戚定满 《海洋工程》2004,22(1):66-73

应用改进的ECOM模式，耦合泥沙输运模型，研究理想河口最大浑浊带形成的动力机制。河口最大浑浊带位于滞流点处，上下游余流均向该处输运泥沙，造成该处泥沙汇合，而由流场辐合产生的上升流又使该处的泥沙不易落淤。南岸(河口东向)的泥沙浓度比北岸高，最大浑浊带位于南岸，这是由于盐水入侵带来的高盐水位于北岸的底层，其斜压效应使底层的环流由北向南流动，把底层高浓度的泥沙向南岸平流，聚集于南岸底层。除上游河流泥沙来源外，强大的涨落潮流冲刷床面，使沉降于床面的泥沙再次悬浮，成为余流输运泥沙的来源之一。  相似文献   

The biology of the catfish Cnidoglanis macrocephalus (Plotosidae) in an Australian estuary     

S. A. Nel  I. C. Potter  N. R. Loneragan 《Estuarine, Coastal and Shelf Science》1985,21(6):895-909

This paper describes the age structure, growth, diet and aspects of gonadal development in the cobbler, Cnidoglanis macrocephalus (Valenciennes), in the large Swan estuary in south-western Australia between August 1982 and June 1984. Analysis of otolith annuli showed that while the 0+ to 3+ age classes were regularly represented in monthly samples, the 4+ and more particularly the 5+ and 6+ were much less abundant. The weighted means for the back calculated lengths at the end of the first to fourth years of life were 181 mm (≡ 26 g), 314 mm (≡ 156 g), 418 mm (≡ 410 g) and 518 mm (≡ 833 g) respectively. The mean length at the end of the second year of life was similar to the minimum legal size for capture by commercial fishermen (320 mm). The von Bertlanffy growth curve calculated from the back calculated lengths was L_t = 917 [1 − e^{−0·20(t + 0·11)}]. The relative weight of mulluscs, crustaceans and polychaetes in the intestine varied markedly between small and large fish, apparently reflecting differences in the size of these prey. The large mean diameter of mature eggs ( ) was correlated with a low mean absolute fecundity (2078). Trends shown by egg size, gonadosomatic index and time of appearance of spent females indicate that spawning takes place between October and December. The attainment of sexual maturity is both age- and size-dependent. Although sexually maturing and occasionally spent fish were found in the lower estuary, meristic values, commercial catch statistics and other data indicate that the cobbler found in the Swan estuary are part of a population which typically spawns at sea.  相似文献   

长江口南汇边滩冲淤变化规律与机制     

火苗  范代读  陆琦  刘阿成 《海洋学报》2010,32(5):41-51

根据1842—2004年海图资料分析发现,南汇边滩存在近百年尺度的强烈冲刷—淤积旋回。长江主泓走南港或北港是造成冲刷期"北滩、东滩淤积,南滩、过渡带冲刷"或淤积期冲淤态势反相的主要原因;冲刷期内风暴强度和频数明显多于淤积期,造成冲刷期滩面叠置记忆的是暴风浪成因的"高滩冲刷、低滩淤积"的冲淤态势,而淤积期保存的是弱风浪成因的"高滩淤积、低滩冲刷"叠置增强的剖面特征。尽管三角洲整体冲淤态势的转变主要受流域来沙量的控制,但不同岸段受河口河势分水分沙作用、潮流和波浪等共同作用,明显存在此冲彼淤、冲淤动态调整等特征。已有的入海泥沙含量阈值研究以点代面或以局部代整体,这是造成阈值估算偏高的主要原因。2003年三峡水库开始蓄水后平均年输沙量154 Mt/a已低于低阈值184 Mt/a,但三角洲尚未如预测那样发生由净淤积向净侵蚀的转变。已有的河口水文观察资料显示,水体含沙量也未发生明显下降,这可能是潮控型三角洲潮流对泥沙在河口的再分配起主导作用,并可能由此延长三角洲冲淤转变对入海泥沙量减少的滞后。今后需进一步加强潮控型河口复杂过程的综合研究,提高对泥沙含量阈值估算和应对可能面临的海岸侵蚀及其相关的环境地质灾害的能力。  相似文献