大连湾水域浮游桡足类的分布

本文根据１９８２年４月至１９８３年５月在大连湾周年生态调查中获得的资料，分析了大连湾浮游桡足类的数量分布和季节变化。结果表明，大连湾共有浮游桡足类２２种，其中优势种大网为中华哲水蚤Ｃａｌａｎｕｓｓｉｎｉｃｕｓ；中网为小拟哲水蚤Ｐａｒｕｃａｌａｎｕｓｐａｒｖｕｓ、拟长腹剑水蚤Ｏｉｔｈｏｎａｓｉｍｉｌｉｓ、短角长腹剑水蚤Ｏｉｔｈｏｎａｂｒｅｖｉｃｏｒｎｉｓ。桡足类总量年高峰，大、中同各有２次，最高峰分别为２月和８月。本文还讨论了几种环境因素对浮游桡足类分布的影响。     

Comparison between zooplankton data collected by the Continuous Plankton Recorder survey in the English Channel and by WP-2 nets at station L4, Plymouth (UK)

Zooplankton sampling has been carried out by the Continuous Plankton Recorder (CPR) survey since the 1930s enabling the study of long-term changes in plankton populations, the elucidation of seasonal patterns of abundance, and more recently providing zooplankton biomass estimates for ecosystem models. Data for zooplankton abundance collected by CPR tows in the Western English Channel (between 1988 and 1998) were compared to vertically integrated samples collected from station L4 off Plymouth, UK. Comparisons were made for locally abundant copepods (including Acartia, Calanus, Para/Pseudocalanus, Centropages, Oithona and Temora) collected by CPR and WP-2 nets. All dominant species recorded at L4 were also common to the CPR data. However, the position of the taxa in the two datasets was not equivalent. Seasonal cycles revealed by CPR data were significantly similar to those recorded throughout the water column at L4 for most taxa. However, absolute levels of abundance differed for the two datasets: abundances were underestimated by CPR samples when compared to those of vertically integrated samples by a factor of between 2 and 35, with the exception of Centropages. The differing mesh sizes (200 and 270 μm) of the WP-2 net and CPR mesh could only partially explain these differences in abundance, implying that the behaviour of individual taxa and their depth in the water column also influenced the abundance recorded.     

Coupling of life cycles of the copepods Calanus chilensis and Centropages brachiatus to upwelling induced variability in the central-southern region of Chile

A time series of zooplankton sampling carried out at Station 18 off Concepción (36°S, 73°W) from August 2002 to December 2003 allowed the study of annual life cycles of the copepods Calanus chilensis and Centropages brachiatus in association with environmental variability in the coastal upwelling zone. Changes in the abundance of eggs, nauplii, and copepodids were assessed from samples taken at a mean time interval of ca. 20 days. Upwelling variability in near-surface waters was reflected in seasonal changes in salinity, water column stratification, and oxycline depth, as well as a weak seasonal signal in sea surface temperature (1-2 °C). Both copepods exhibited similar life cycles, characterized by continuous reproduction throughout the year. Estimates of generation times, as a function of temperature, were 25-30 days for C. chilensis and 27-35 days for C. brachiatus, predicting about 12 and 10 generations a year, respectively. These estimates were consistent with reproduction pulses observed in the field. It was thus suggested that copepods may grow under non-limiting food conditions in this upwelling area. However, despite continuous reproduction, there were abrupt changes in population sizes along with the disappearance of early naupliar and copepodid stages taking place even during the upwelling season (spring/summer). These changes were attributed to sudden increases in mortality taking place in spring or early summer, after which the populations remained at low levels through the fall and winter. It is thus suggested that, in addition to variability in the physical environment, biological interactions modulating changes in copepod mortality should be considered for understanding copepod life cycles in highly productive upwelling systems.     

Cross-shelf distribution of copepods and the role of event-scale winds in a northern California upwelling zone

Cross-shelf distribution and abundance of copepod nauplii and copepodids were measured during three summer upwelling seasons (2000–2002) in a coastal upwelling zone off northern California. These 3 years varied considerably in the intensity of winds, abundance of chlorophyll, and water temperature. The cruises in 2000 were characterized by relaxation conditions, with generally high levels of chlorophyll and high water temperature. The cruises in 2001 and 2002 were dominated by strong and persistent upwelling events, leading to lower chlorophyll and water temperatures. The copepod assemblage was dominated by Oithona spp., Acartia spp. and Pseudocalanus spp., with Metridia pacifica (lucens), Microsetella rosea, Oncaea spp. and Tortanus discaudatus also common during all 3 years. The cross-shelf distribution of copepods was generally shifted offshore during upwelling and onshore during relaxation events, although some variability between species occurred. Abundance of all life stages generally exhibited a negative correlation with cross-shelf transport averaged over at least 1–4 days and lagged by 0–3 days, indicating lower abundances during and immediately after active upwelling. However, copepod nauplii seemed to respond positively to wind events lasting 1–5 days followed by a period of relaxation lasting 6 or 7 days. These rapid rates of change in abundance are probably too great to be due to in situ growth and reproduction alone; physical processes must also play a role. These results suggest a highly dynamic relationship between copepods and upwelling events off northern California, with species-specific responses to upwelling to be expected.     

Epikarst communities: biodiversity hotspots and potential water tracers

There is an exceptionally rich aquatic fauna in the epikarst, the skin of karst. High species richness in the epikarst, coupled with its special vulnerability as the first point of entry of nearly all toxic spills, makes its protection especially important. The epikarst fauna may also be an useful tool in tracing the potential route of pollutants. Copepods in epikarst have extremely local distributions, and their body size is such that they are largely at the mercy of directional flows. In a series of caves in southwest Slovenia and West Virginia, a significant fraction of the copepod species occur in less than 100 m of linear extent. This suggests a pattern of highly restricted lateral flow under normal conditions and the distribution of copepods could potentially be used to trace water movement. Under high flow conditions as would often be the case with toxic spill, mounding of water may increase the lateral radius of flow. Nevertheless, copepods may be useful tracers.     

小型桡足类在海洋生态系统中的功能作用

依据渤海周年的中型浮游动物网样品 ,研究了小型桡足类的优势种小拟哲水蚤(Paracalanusparvus)、强额拟哲水蚤 (Paracalanuscrassirostris)和双刺纺锤水蚤 (Acartiabifilosa)生物量的季节变动、分布和年产量 ,并与渤海大型桡足类的优势种中华哲水蚤 (Calanussinicus)进行了比较。结果表明 ,三种小型桡足类成体的年产量分别为 2 4 .89、1 0 .83和 1 9.5 4mgC/(m3·a) ,中华哲水蚤的年产量为 1 8.30mgC/(m3·a)。小型桡足类主要分布在近岸 ,特别是渤海湾和莱州湾 ,这里正好是许多经济鱼类的产卵场和育幼场 ;而中华哲水蚤主要分布在中央水域。小型桡足类的高峰季节持续时间长 ,从 4月到 1 0月 ,覆盖了几乎所有仔稚鱼大量出现的月份 ;而中华哲水蚤高峰季节持续时间短 ,仅 6月和 7月。另外 ,在粒度上 ,小型桡足类的卵、无节幼体、桡足幼体和成体都比中华哲水蚤等大型桡足类小了一个数量级 (按体积计 ) ,特别适合作为仔稚鱼的饵料。因此认为 ,在近海生态系统中 ,小型桡足类较之大型桡足类起更为重要的作用     

Reproductive success of Calanus pacificus during diatom blooms in Dabob Bay, Washington

While numerous laboratory studies in the last decade have shown that diatoms can induce reproductive failure in copepods, field evidence for a negative diatom effect is equivocal. To unambiguously elucidate the effects diatoms have on copepod reproduction in situ, we undertook a study of the abundance, distribution, grazing rates, and reproductive success of Calanus pacificus in Dabob Bay, Washington, USA, during two spring bloom periods. We simultaneously measured the phytoplankton composition, abundance, and distribution. Here we present results for the reproductive success of C. pacificus using four measurements: egg production rate, clutch size, egg hatching success, and naupliar survival (to the first feeding stage). Egg production rate was positively correlated with chlorophyll a concentration, and egg hatching success and naupliar survival were usually greater than 80%. However, in February 2002 and 2003 – during blooms of diatoms of the genus Thalassiosira – either egg hatching success, naupliar survival, or both were significantly depressed compared to other times in spring and summer. These effects, combined with evidence that C. pacificus was grazing aldehyde-producing Thalassiosira at the time of their blooms, indicate that diatoms can negatively affect copepod reproduction in the field, albeit only under specific circumstances and for brief periods.     

莱州湾夏季浮游桡足类的摄食研究

于１９９７年７月有（１９－２４日）和小湖（２６－３０日）期间在莱州湾对不同大小桡足类自然群体（大型：〉５００ｍｍ,小型：２００－５００ｍｍ）的分布及肠道色素含量进行了现场测定,并在一个４８ｈ连续观测站（Ａ４）进行了肠道排空率和摄食节律实验。结果表明,浮动物肠道色素含量随个体的增大而增加,大型桡足类存在着一定的昼夜摄食节律,摄食高峰出现在夜间,小型桡足类摄食切律不明显。Ａ４站测得的桡足类摄食结果表明     

Assessment of storage lipid accumulation patterns in eucalanoid copepods from the eastern tropical Pacific Ocean

Members of the copepod family Eucalanidae are widely distributed throughout the world׳s oceans and have been noted for their accumulation of storage lipids in high- and low-latitude environments. However, little is known about the lipid composition of eucalanoid copepods in low-latitude environments. The purpose of this study was to examine fatty acid and alcohol profiles in the storage lipids (wax esters and triacylglycerols) of Eucalanus inermis, Rhincalanus rostrifrons, R. nasutus, Pareucalanus attenuatus, and Subeucalanus subtenuis, collected primarily in the eastern tropical north Pacific near the Tehuantepec Bowl and Costa Rica Dome regions, noted for its oxygen minimum zone, during fall 2007 and winter 2008/2009. Adult copepods and particulate material were collected in the upper 50 m and from 200 to 300 m in the upper oxycline. Lipid profiles of particulate matter were generated to help ascertain information on ecological strategies of these species and on differential accumulation of dietary and modified fatty acids in the wax ester and triacylglycerol storage lipid components of these copepods in relation to their vertical distributions around the oxygen minimum zone. Additional data on phospholipid fatty acid and sterol/fatty alcohol fractions were also generated to obtain a comprehensive lipid data set for each sample. Rhincalanus spp. accumulated relatively large amounts of storage lipids (31–80% of dry mass (DM)), while E. inermis had moderate amounts (2–9% DM), and P. attenuatus and S. subtenuis had low quantities of storage lipid (0–1% DM). E. inermis and S. subtenuis primarily accumulated triacylglycerols (>90% of storage lipids), while P. attenuatus and Rhincalanus spp. primarily accumulated wax esters (>84% of storage lipids). Based on previously generated molecular phylogenies of the Eucalanidae family, these results appear to support genetic predisposition as a major factor explaining why a given species accumulates primarily triacylglycerols or wax esters, and also potentially dictating major fatty acid and alcohol accumulation patterns within the more highly modified wax ester fraction. Comparisons of fatty acid profiles between triacylglycerol and wax ester components in copepods with that in available prey suggested that copepod triacylglycerols were more reflective of dietary fatty acids, while wax esters contained a higher proportion of modified or de novo synthesized forms. Sterols and phospholipid fatty acids were similar between species, confirming high levels of regulation within these components. Similarities between triacylglycerol fatty acid profiles of E. inermis collected in surface waters and at >200 m depth indicate little to no feeding during their ontogenetic migration to deeper, low-oxygen waters.