50年来北海市滨海湿地景观格局变化及其驱动机制   总被引：2，自引：2，他引：0       下载免费PDF全文

梁文  胡自宁  黎广钊  宋垠先  余克服  农华琼 《海洋科学》2016,40(2):84-93

以1955~2004年遥感影像为数据源,结合野外调查,运用景观生态学原理,研究50 a间北海市滨海湿地的景观格局及其动态变化。结果表明,50 a间北海市滨海湿地呈整体退化趋势,潮间砂质海滩、潮间淤泥质海滩、红树林滩、小型岛屿湿地减少;景观格局指数显示1977年、1998年是北海市滨海湿地较明显变化的拐点。1977年人类活动影响增加,滨海湿地稍有退化,湿地景观多样性指数减小,优势度指数增加,均匀度指数减小、景观总面积指数降至最低值。1988年湿地保护力度加大,湿地略为好转,景观多样性指数、优势度指数、均匀度指数则呈相反规律。1998年湿地受到的极端气候灾害、人类干扰程度加大,平均斑块分形维数下降,斑块密度指数、景观斑块数破碎化指数呈最高值。湿地景观格局指数的变化,反映了围垦改造、互花米草的生物入侵、城市污染、极端气候灾害等对景观格局的影响,人类活动是北海市滨海湿地景观格局变化的主要驱动因子。  相似文献   

Influence of prey abundance and abiotic factors on the long-term home-range and movement dynamics of spotted grunter Pomadasys commersonnii in an intermittently open estuary     

BA Maree  PD Cowley  TF Næsje  A-R Childs  AI Terörde  EB Thorstad 《African Journal of Marine Science》2016,38(2):171-180

Long-term home-range and movement dynamics of spotted grunter Pomadasys commersonnii and the distribution of their dominant prey, the sandprawn Callichirus kraussi, were investigated in the intermittently open East Kleinemonde Estuary, South Africa. In addition, the effects of fish length, diel cycle, season and other abiotic factors on home range and area use were examined. Nine adult spotted grunter (326–489?mm total length) were tagged with acoustic transmitters, and their movements were studied by manual tracking on six consecutive days and nights during each of five tracking sessions from March to November 2004. In addition, movement patterns were recorded by stationary data-logging receivers. Kernel home ranges (95% utilised distribution) varied in size (mean: 76 797?m²?, range: 26 296–165 321?m²), but were all located in the lower one-third of the 3.6 km-long estuary. There was no effect of season, the diel cycle or fish length on the home-range estimates. However, the distribution of prey corresponded with the home-range distribution of tagged fish. Although sandprawn distribution was highly variable within and among transects and depth classes, sandprawns were most abundant in the lower region of the estuary, which corresponded to the home-range distribution of spotted grunter. Spatial distribution of prey appears to be a dominant factor influencing home-range parameters of this species within an intermittently open estuary.  相似文献   

Age and growth of Cape stumpnose Rhabdosargus holubi (Pisces: Sparidae) in the Eastern Cape,South Africa     

MW Farthing  NC James  WM Potts 《African Journal of Marine Science》2016,38(1):65-71

Rhabdosargus holubi is a small (maximum weight=2.4?kg) yet important fishery species in the estuaries of the south-east coast of South Africa. Little is known of its biology and specifically its growth rate, which is essential for sustainable management of the fishery. We examined and counted the opaque zones in the sectioned otoliths of 134 R. holubi to determine its age and growth parameters. The otoliths from two recaptured fish marked with oxytetracycline confirmed that one opaque zone was deposited annually. The species reached a maximum age of 18 years and growth was adequately described by a von Bertalanffy growth function of the form: L_t = 358.1 (1 – e^{?0.24(t+0.77)}) mm fork length. There were no significant differences between any of the male and female growth parameters (likelihood ratio test: p = 0.3). The growth was slow (omega index: ω = 86.56); however, despite this, the unique life history of R. holubi may provide a degree of resilience to heavy fishing pressure in estuaries.  相似文献   

黄河三角洲芦苇湿地生态修复效果评价研究   总被引：1，自引：0，他引：1  

柏建坤  臧震宇  冯建祥  林光辉 《湿地科学与管理》2016,(3):17-22

基于黄河三角洲芦苇湿地退化现状及所实施的生态修复工程,以正负参照系选取了4块不同修复年限的样地,从湿地生态系统的环境质量、结构与功能的角度构建了湿地修复效果评价指标体系,利用层次分析法确定各指标权重,利用模糊综合评价法对黄河三角洲盐渍化芦苇湿地的修复效果进行定量评价。结果表明:黄河三角洲芦苇湿地4年修复期的样地评价得分为4.01,2年修复期的样地评价得分为3.16,对应评价结果分别为"优"和"良"的等级。相比负向对照,修复区的水体指标和土壤指标参数显著改善,而植被生物量和密度与自然样地还有较大差距,说明生物群落的建立需要更长的时间;同时,湿地水资源管理是该区芦苇湿地生态修复工程的关键,应根据芦苇不同生长期的需水量,制定合理的抽灌制度,达到洗碱脱盐和植被建群的双重目的。  相似文献   

The carbohydrates in relation to mineralogic and granulometric composition of surface sediments in the karst estuary (River Krka estuary,Yugoslavia)     

Olga Hadz̆ija  Mladen Jurac̆ić  Marija Luić  Maja Tonković  Biserka Jeric̆ević 《Estuarine, Coastal and Shelf Science》1985,21(5):701-709

The investigation of mineral, granulometric and chemical composition of sediments of the River Krka estuary (Yugoslavia) were performed in order to elucidate the origin of the sediments and the pattern of sedimentation. Estuarine surface sediments were found to be fine-grained with a bimodal distribution. Environmental conditions in estuarine sediments favour conservation of the organic matter (anoxic conditions). The carbohydrates in the sediments were investigated to determine whether they are of terrigenous or authigenous origin. Glucose, galactose, mannose, xylose, rhamnose, glucosamine and glucuronic acid were detected in the sediments. Their mutual relationship indicates a preferentially terrigenous source of sedimented organic material in estuarine sediments.  相似文献   

The exchange of organic carbon in basin mangrove forests in a southwest Florida estuary     

Robert R. Twilley 《Estuarine, Coastal and Shelf Science》1985,20(5):543-557

The magnitude and seasonality of organic carbon exchange was estimated for two basin mangrove forests in Rookery Bay, Florida. Runoff and tidal inundation in the forests were seasonal with half the annual total of each occurring from August to October. In each forest there were 152 tides yr^?1 with a cumulative depth of about 12 m. Total organic carbon increased in bay waters exporting from the mangroves following a flood tide and peak concentrations were associated with export due to rainfall. The amount of net export from each basin forest was similar, although the concentration of organic carbon in each were different. Monthly net organic carbon export was proportional to the cumulative tidal amplitude within the forest. Total organic carbon export was 64 gC m^?2 yr^?1 and DOC was 75% of the total. A comparison of organic carbon export among riverine, fringe and basin mangroves suggests that tidal hydrology influences the proportion of litter fall that is exported from mangroves; and the magnitude of this organic carbon export from mangroves is related to the cumulative tidal amplitude within the forests.  相似文献   

Subtidal sea level and current variations in the northern reach of San Francisco Bay     

Roy A. Walters  Jeffrey W. Gartner 《Estuarine, Coastal and Shelf Science》1985,21(1):17-32

Analyses of sea level and current-meter data using digital filters and a variety of statistical methods show a variety of phenomena related to non-local coastal forcing and local tidal forcing in the northern reach of San Francisco Bay, a partially mixed estuary. Low-frequency variations in sea level are dominated by non-local variations in coastal sea level and also show a smaller influence from tidally induced fortnightly sea level variations. Low-frequency currents demonstrate a gravitational circulation which is modified by changes in tidal-current speed over the spring-neap tidal cycle. Transients in gravitational circulation induce internal oscillations with periods of two to four days.  相似文献   

Particulate organic matter in the coastal and estuarine waters of Goa and its relationship with phytoplankton production     

X.N. Verlencar  S.Z. Qasim 《Estuarine, Coastal and Shelf Science》1985,21(2):235-243

In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l^?1 and from 0.28 to 5.24 mg l^?1 and particulate phosphorus (PP) varied from 0.71 to 5.18 μg l^?1 and from 0.78 to 20.34 μg l^?1, respectively. The mean values of chlorophyll and primary productivity were 1.94 mg m^?3 and 938.1 mg C m^?2 day^?1 in the coastal waters and 4.3 mg m^?3 and 636.5 mg C m^?1 day^?1 in the estuarine waters, respectively.$\text{POC}\text{chl}$ ratios were low in June and October even when POC values were quite high. The POC in surface waters was linearly correlated with the chlorophyll content. Also PP increased when chlorophyll and primary productivity remained high. The results suggest that the phytoplankton was sharply increasing and contributed to POC and PP content. The percentage of detritus calculated from the intercept values of chlorophyll on POC varied from 46 to 76% depending on season. Results indicate that the major portion of POC and PP during postmonsoon (October–January) is derived from phytoplankton production while the allochthonous matter predominate during monsoon (June–September).  相似文献   

Intertidal macroalgae and macroinvertebrates: Seasonal and spatial abundance patterns along an estuarine gradient     

Morgan N. Hardwick-Witman  Arthur C. Mathieson 《Estuarine, Coastal and Shelf Science》1983,16(2):113-129

Quantitative sampling of the dominant intertidal epibiota was conducted seasonally along an estuarine gradient within the Great Bay Estuary System, New Hampshire, U.S.A. The abundance and zonation of the dominant macroorganisms varied with distance into the estuary. Replacement of marine by estuarine species occurred, and overall abundance and species richness decreased along the estuarine gradient. Zonation patterns within the inner estuary were primarily allied with substrata. Maximum abundance of invertebrates occurred in the mid-intertidal zone where a dense fucoid canopy provided habitat heterogeneity. Densities of epibiotic organisms decreased toward low water, especially in the inner estuary where hard substratum was limiting. Settlement blocks, introduced into the low intertidal zone, were dominated by barnacles and fucoid algae; after 16 months, the species composition on the settlement blocks resembled the adjacent community. Semibalanus balanoides settled in the spring, while Fucus vesiculosus var. spiralis exhibited low but constant settlement. Despite the physical rigors of the estuarine environment, only Semibalanus balanoides, Ilyanassa obsoleta and Spartina alterniflora showed significant seasonal changes in density. Thus, there are predictable and persistent epibiotic species assemblages within the intertidal zone of the Great Bay Estuary System.  相似文献   

Estuarine retention of larvae of the crab Rhithropanopeus harrisii     

Thomas W. Cronin 《Estuarine, Coastal and Shelf Science》1982,15(2):207-220

Larvae of estuarine organisms continually face possible export from the parent estuary. Retention of larvae of the estuarine crab Rhithropanopeus harrisii was investigated in the upper Newport River estuary, North Carolina. All of the developmental stages occurred in the same area of the estuary with similar horizontal distributions, and the concentrations of intermediate and late stages were not greatly reduced from those of the first larval stage. This was strong evidence for the continuous retention of larvae in the upper estuary.To determine mechanisms by which retention might be effected, field studies of the vertical distributions and migrations of these larvae were made. The four zoeal stages had similar but complex vertical migration patterns, which varied from study to study. These migrations centered on the depth of no net flow, reducing longitudinal transport during development. Cross-spectral analysis of the larval migrations and the environmental cycles of light, salinity and current speed revealed that each of these external cycles affected larval depth. Megalopae of R. harrisii also migrated vertically, but they were present in much lower concentrations than the zoeal stages, an indication of a change to benthic existence in this final larval form.  相似文献