Intertidal sand‐dwelling Peracarid fauna of North Island,New Zealand

Abstract

Substrate and infauna samples were taken at four tidal levels (mean high water springs, high mid beach, low mid beach, and mean low water neaps) with a 0.0625 m² quadrat at 14 North Island beaches in New Zealand. The distributions of Peracarida (Crustacea) were correlated with sediment type, tidal height, and degree of exposure; sampling began in March 1972 and was completed in November 1973.

Substrate samples were sieved and median diameter of the particles ranged from very coarse sand of — 0.60? to very fine sand of + 3.259?. Substrates were variously sorted: ? quartile deviation ranged from 0.14? to 0.66?, skewness from ‐ 0.08? to + 0.07?.

Peracarid fauna was moderately abundant; the maximum value was 720 animals per square metre on a fully exposed beach. Highest average abundance (303 per square metre) for the 14 beaches was recorded from the mean low water neap station. Amphipoda was the dominant group (54% of all Peracarida recorded), followed by Isopoda (33%) and Cumacea (13%). Frequency of occurrence at the 56 stations was headed by Amphipoda (64%), followed by Isopoda (46%), and Cumacea (20%).

The results are compared with data from Stewart Island beaches, and the biogeographical distributions of recorded Peracarida are discussed. An unexpectedly high degree of endemism exists for a warm‐temperate region, caused by the isolation of New Zealand, which has no direct shallow water contact with tropical or cold temperate regions.     

广东博贺澙湖潮滩的冲淤变化及其动力作用分析

基于遥感技术,对反映17 a来博贺澙湖的5景遥感影像定量反演潮滩水边线,在此基础上推算澙湖潮滩的沉积与冲刷速率,同时对引起潮滩变化的动力作用进行探讨,结果表明博贺澙湖的潮滩以淤展为主,其中处于开敞地段的澙湖潮滩出现冲刷,遮蔽岸段的澙湖潮滩淤积,控制澙湖潮滩变化的主要因子是包括圈围潮滩成盐田、虾池以及鱼塘等的人类活动.     

Long-term bottom water warming in the north Ross Sea

We measured potential temperature, salinity, and dissolved oxygen profiles from the surface to the bottom at two locations in the north Ross Sea (65.2°S, 174.2°E and 67.2°S, 172.7°W) in December 2004. Comparison of our data with previous results from the same region reveals an increase in potential temperature and decreases in salinity and dissolved oxygen concentration in the bottom layer (deeper than 3000 m) over the past four decades. The changes were significantly different from the analytical precisions. Detailed investigation of the temperature, salinity, dissolved oxygen and σ ₃ value distributions and the bottom water flow in the north Ross Sea suggests a long-term change in water mass mixing balance. That is to say, it is speculated that the influence of cool, saline, high-oxygen bottom water (high-salinity Ross Sea Bottom Water) formed in the southwestern Ross Sea has possibly been decreased, while the influences of relatively warmer and fresher bottom water (low-salinity Ross Sea Bottom Water) and the Adélie Land Bottom Water coming from the Australia-Antarctic Basin have increased. The possible impact of global warming on ocean circulation needs much more investigation.     

波速线性变化介质中地震波传播特征

根据变速介质中地震波传播所满足的变系数波动方程,推导出波速线性变化介质中一维波动方程的解析解,讨论了波速不均匀性对地震波传播的影响：地震波振幅衰减大小与介质速度梯度有关;频率转折点两侧地震波传播性质;频率与地震波波速关系。     

珊瑚礁中Mn2+的ESR信号及其古气候指示意义

１９８９年３－５月在海南岛三亚浅钻取心,用岩石地层学和地质年代学方法研究了海南岛周缘珊瑚礁的基本特征和成礁时代,在此岩心的基础上进一步研究珊瑚礁的ＥＳＲ谱学特征。结果表明,珊胡礁Ｍｎ＾２＋的ＥＳＲ信号和古气候变化直接相关,在１００％文石基础上归一的Ｍｎ＾２＋ＥＳＲ信号是一种新的灵敏的古气候指示物,其指示的古气候变化和前人发表的研究成果相一致,海南岛三亚珊瑚礁的Ｍｎ＾２＋ＥＳＲ信号表明,中国全新世大     

中国近海生态环境变化的同位素示踪研究

同位素在确定物质来源、指示生物地球化学循环路径、定量生物地球化学过程速率等方面具有独特的优势,本文以近海生态环境变化研究中常用的稳定同位素（13C、15N、18O）和放射性核素（14C、234Th、232Th、230Th、228Th、210Po、210Pb、137Cs、226Ra、228Ra、224Ra、223Ra）为对象,介绍它们在揭示海洋有机质来源、食物网结构、水体缺氧机制、氮循环过程、颗粒动力学、海底地下水输入、有机地球化学过程、沉积年代学等方面的应用,侧重于总结我国近海生态环境研究中同位素示踪取得的进展。伴随着我国经济的发展,近百年来我国近海生态环境也发生了明显的变化,基于同位素示踪揭示的近海富营养化和沉积环境的演变规律表明,我国近海生态环境自20世纪50年代起经历持续的变化,特别是在过去20~30年时间里,近海生态环境的变化尤为剧烈,反映出人类活动是我国近海生态环境变化的主要驱动力。未来需要通过发展新的同位素技术及拓展更广泛的应用,围绕近海海洋生态环境变化的突出问题,重点揭示近海生态环境变化的响应特征、变化速率和作用机制,从而系统地掌握近海生态环境的时空变化规律。     

LEADAT: a MATLAB-based program for lead-210 data analysis of sediment cores

1Introduction Tracking the history of man s impact on the en-vironment, it is clear that in many places the periodof greatest impact and most dramatic transformationlies within the last 150 a (Oldfield and Appleby,1984). Many aspects of this impact can be…     

基于遥感技术对黄河口水色与岸线季相变化特征研究

使用Landsat-5 TM 2004年11月24日与2005年5月13日黄河口遥感影像,配合准同期外业实测资料,进行黄河口水体水色物质叶绿素a与悬浮泥沙的动态反演与河口岸线解译.研究表明由于秋末与春初黄河上游来水物质含量的差异,上述悬浮指标值存在显著的季相差异.根据样值与光谱特征建立的反演模型得出的反演值与实测值有平均在0.85以上的相关关系,具有很好的反演效果.岸线解译成果表明,黄河口岸线演变迅速,在河流平枯水量时期仍然具有较强的变化,岸线推进尤以新河口附近显著.这表明,使用遥感手段是进行河口生态环境质量监测的有效手段,是进行岸线动态变化研究的一种基本技术支撑手段.     

Seasonal variability in free-living marine nematode community structure in a sandy beach of the Taiping Bay of Qingdao, China

Nematode assemblage composition, trophic structure and biodiversity were followed over an annual cycle in a sandy beach of the Taiping Bay of Qingdao, China. Nematode assemblage in the sandy beach maintained a high genus diversity （75 genera）. Mlero- laimus and Bathylaimus were the dominant genus of the nematode assemblage, accounting for 66% of the total nematode abundance. The nematodes＇ dominant trophic structure changed seasonally as a response to the seasonal changes in food quality. Epigrowth-feeder nematodes （2A） were the dominant trophic groups in the trophic structure with the highest abundance in spring because of phytoplankton bloom, while the feeding type （ 1 B） showed higher abundance in summer that was due to the increasing of sediment detritus after spring bloom. Furthermore, species diversity and evenness calculated on nematodes identified to the genus level displayed significant temporal changes, which was also reflected by the index of trophic diversity. According to the cluster analysis, the nematode community structure of the whole year was clearly separated into two periods （A and B）. Biota-Envlron- ment matching （BIOENV） results showed that seawater temperature, sediment Chl a and grain size were responsible for the nema- tode community structure variation in spring and summer period （Period A）. However, seawater/interstitial water temperature, interstitial water dissolved oxygen concentration,interstitial water salinity, and sediment Ph a a were more important in constructing the autumn and winter period （Period B） nematode community structure.