基于卫星遥感的潮滩植被、高程、潮沟空间关系探讨-以崇明东滩为例

The analysis of vegetation-environment relationships has always been a study hotspot in ecology. A number of biotic, hydrologic and edaphic factors have great influence on the distribution of macrophytes within salt marsh.Since the exotic species Spartina alterniflora(S. alterniflora) was introduced in 1995, a rapid expansion has occurred at Chongming Dongtan Nature Reserve(CDNR) in the Changjiang(Yangtze) River Estuary, China.Several important vegetation-environment factors including soil elevation, tidal channels density(TCD),vegetation classification and fractional vegetation cover(FVC) were extracted by remote sensing method combined with field measurement. To ignore the details in interaction between biological and physical process,the relationship between them was discussed at a large scale of the whole saltmarsh. The results showed that Scirpus mariqueter(S. mariqueter) can endure the greatest elevation variance with 0.33 m throughout the marsh in CDNR. But it is dominant in the area less than 2.5 m with the occurrence frequency reaching 98%. S. alterniflora has usually been found on the most elevated soils higher than 3.5 m but has a narrow spatial distribution. The rapid decrease of S. mariqueter can be explained by stronger competitive capacity of S. alterniflora on the high tidal flat. FVC increases with elevation which shows significant correlation with elevation(r=0.30, p0.001). But the frequency distribution of FVC indicates that vegetation is not well developed on both elevated banks near tidal channels from the whole scale mainly due to tidal channel lateral swing and human activities. The significant negative correlation(r=–0.20, p0.001) was found between FVC and TCD, which shows vegetation is restricted to grow in higher TCD area corresponding to lower elevation mainly occupied by S. mariqueter communities. The maximum occurrence frequency of this species reaches to 97% at the salt marsh with TCD more than 8 m/m2.     

Spatial distribution of zooplankton in the intertidal marsh creeks of the Yangtze River Estuary,China

Zooplankton are important grazers of primary production within intertidal marshes and are the optimal prey of higher trophic consumers; however, the patterns of their spatial distribution in marsh creeks are rarely reported. The zooplankton in the intertidal creeks with different salinities at Dongtan marshes of the Yangtze River Estuary was surveyed. The mean zooplankton densities in the intertidal creeks were 53,638 ind. m⁻³ in April and 132,916 ind. m⁻³ in July, respectively, which were as high as in the near-shore subtidal waters of the Yangtze River Estuary. This high abundance implied the important roles of zooplankton in the matter flux between marshes and near-shore waters through complex intertidal creek systems. Zooplankton total densities changed significantly from northern to southern creeks. ANOSIM and CCA analyses revealed that the zooplankton community structure were significantly different among the northern, eastern and southern creeks, and between two sampling seasons. Salinity accounted for most of the spatial variation of zooplankton community, whereas water temperature, chlorophyll a concentration, and pH were the main reasons of the temporal variation observed. Copepods were the most abundant zooplankton group. A total of 24 copepod species, belonging to 15 families and 20 genera, were recorded. Planktonic copepods preferred the northern and eastern creeks, with higher densities in July than in April, while benthic copepods predominated only in the northern creeks in April. Since the role of benthic and planktonic copepods may differ in transporting nutrients in the intertidal creeks, it is suggested that the variations in their distribution may influence the ecological functions of zooplankton in the estuarine matter fluxes both spatially and temporally.     

厦门湾红树林生境适宜性评估及修复潜力分析

为定量评估多元环境因子对红树林分布的影响,探索区域红树林生境适宜性和修复潜力的空间分布格局,本研究应用最大熵模型评估厦门湾红树林生境适宜性,叠加土地利用/覆被数据分析红树林修复潜力。结果表明,在生物气候、地形、水质、沉积物、水文等5组环境变量中,影响厦门湾研究区内红树林分布的主要环境变量类型为温度、地形和水质。在单项环境因子中,离岸线距离、营养盐浓度、盐度等对厦门湾红树林生境适宜性的贡献度最大。适宜性和修复潜力较高的区域主要分布于九龙江河口、翔安下潭尾、海沧东屿等区域。与现存红树林的分布相对照,理论上还有约406.4 hm^2的高修复潜力区和1001.2 hm^2的中修复潜力区可考虑用于未来红树林修复。现有的保护区和修复工程已基本覆盖了上述大部分区域,未来厦门湾内的红树林修复选址可考虑泉州市安海湾沿岸、龙海市九龙江河口、漳州港沿岸和附近岛屿。本研究尝试采用新兴模型方法判断红树林的综合适生条件,并实现空间化、定量化的评估,其结果可为红树林修复选址提供重要的科学依据,并为区域红树林保护与修复管理提供决策支持。     

我国瓯江口和珠江口凤鲚洄游模式和生境利用研究

Habitat use of the tapertail anchovy(Coilia mystus Linnaeus, 1758) from the Oujiang River Estuary and the Zhujiang(Pearl) River Estuary was studied by examining the environmental signatures of Sr and Ca in otoliths using electron probe microanalysis. Individuals from the Oujiang River had higher and varied Sr:Ca ratios(expressed as(Sr:Ca)×1 000, 3.83–13.0 average) in the otolith core regions, suggesting that they were born in brackish or sea waters, and that a freshwater habitat might not be necessary for egg hatching and larval growth.While, individuals from the Zhujiang River had lower Sr:Ca ratios(0.39–2.51 average) in the core regions,suggesting a freshwater origin. After hatching, anchovies from the Zhujiang River migrate downstream to the river estuary close to brackish water. Our results demonstrated varied habitat use for spawning during stages of early life history between the two populations, and suggested that such variations are promoting diversity of life history strategies of this species.     

海州湾春季皮氏叫姑鱼栖息地适宜性研究

根据2011年及2013-2015年春季在海州湾及其邻近海域进行的底拖网调查数据,结合同步采集的底层水温、底层盐度、水深以及资源密度等数据,开展皮氏叫姑鱼（Johnius belangerii）栖息地适宜性的相关研究。利用提升回归树（boosted regression tree,BRT）模型确定各环境因子的权重,分别采用算术平均法（AMM）和几何平均法（GMM）建立栖息地适宜性指数（habitat suitability index,HSI）模型,并通过交叉验证确定最优模型。结果表明,皮氏叫姑鱼幼体最适栖息的底层水温为17.4~18.0℃,底层盐度为29.2~30.8,水深为7 m以浅;成体最适栖息的底层水温为17.3~18.0℃,底层盐度为28.8~30.8,水深为12 m以浅。根据BRT模型的输出结果显示,对皮氏叫姑鱼幼体总偏差贡献率最大的是水深,其次是底层盐度和底层水温;对成体总偏差贡献率最大的是底层水温,其次是水深和底层盐度。通过交叉验证发现,无论幼体还是成体,运用GMM算法,且赋予权重的HSI模型具有较低的赤池信息准则值（akaike information criterion,AIC）。海州湾春季皮氏叫姑鱼的最适栖息地随生长阶段而变化,幼体的最适栖息地（HSI ≥ 0.7）主要分布在7 m等深线以浅的山东、江苏沿岸海域;成体的最适栖息主要分布于12 m等深线以浅的海域。海州湾春季皮氏叫姑鱼幼体和成体最适栖息地的空间分布与其自身的生态习性、外界环境因子以及黄海冷水团、近岸沿岸流等因素密切相关。     

生物和非生物因子对秋季海州湾长蛇鲻栖息地适宜性的影响

根据2011年和2013−2018年秋季在海州湾及邻近海域进行的底拖网调查数据,结合同步采集的底层水温、底层盐度、水深、资源密度、饵料生物等生物和非生物因子数据,开展长蛇鲻(Saurida elongata)栖息地适宜性的相关研究。利用提升回归树(Boosted Regression Tree, BRT)模型确定各环境因子的权重,分别采用算术平均法和几何平均法建立栖息地适宜性指数(Habitat Suitability Index, HSI)模型,并通过交叉验证确定最优模型。结果表明：海州湾长蛇鲻在秋季最适宜栖息的底层水温范围为17.5～18℃,最适底层盐度范围为31.3～32.0,最适水深范围为24～37 m;选择其3种主要饵料生物作为生物因子,即枪乌贼(Loligo spp.)、戴氏赤虾(Metapenaeopsis dalei)和六丝钝尾鰕虎鱼(Amblychaeturichthys hexanema),与底层水温、底层盐度和水深共同作为影响因子建立HSI模型。结果显示,对长蛇鲻空间分布总偏差贡献率最高的是饵料因子,其次是水深和底层水温。通过交叉验证发现,运用算术平均算法,且赋予权重的HSI模型具有较低的赤池信息准则值(Akaike Information Criterion, AIC)。研究发现,海州湾秋季长蛇鲻的最适栖息地(HSI≥0.7)主要分布在34.5°～36°N,119°～121°E之间,其中35°～36°N海域的最适栖息地分布范围大,而且从近岸至远海,HSI指数有增加的趋势。     

珠江口内伶仃洋晚第四纪黏土矿物组成特征及对源区气候变化的指示

黏土矿物组合和相对含量变化可反映源区地表风化过程,进而推断古气候的周期性变化,因此黏土矿物分析是古气候重建的重要手段之一。对珠江口内伶仃洋13-LD-ZK20钻孔晚第四纪沉积物中黏土矿物组成进行分析,结果显示黏土矿物主要为蒙脱石（含伊利石/蒙脱石无序混层）,平均相对含量为49%,其次为伊利石、高岭石和绿泥石,平均相对含量分别为20%、19%和12%。伊利石化学指数较高（多数大于0.4）,指示源区强烈的化学风化作用。珠江口内伶仃洋晚第四纪以来黏土矿物根据其相对含量变化和岩芯是否受成岩作用影响可分为4个阶段,指示西江源区气候总体暖-冷-暖的变化趋势。晚更新世第1阶段黏土矿物受成岩作用影响,不具古气候指示意义,第2阶段初期较为温暖,末期存在短期气候相对干冷阶段,可能与晚更新世末次冰盛期有关,第3阶段前期稍转暖。全新世（第3阶段后期和第4阶段）主要为温暖潮湿气候特征,并存在短期冷-暖波动。