秦皇岛近岸海域夏季小型水母分布特征

本研究基于2014—2018年每年8月份,于秦皇岛海域使用浅水Ⅰ型浮游生物网采集的浮游动物样品数据,分析了小型水母群落的组成种类和丰度分布特征及环境因子与水母群落特征之间的关系。结果如下:2014—2018年调查海域共出现小型水母13种,其中2014、2015和2017年夏季水母种类数均为7种, 2016年夏季水母种类数为6种, 2018年夏季水母种类数最少,仅为2种。秦皇岛近岸水域水母的优势种包括薮枝螅水母、球型侧腕水母和锡兰和平水母。2016年夏季秦皇岛水域水母丰度的平均值最高,达到了95.0 ind./m3。2014、2015和2018年分别为66.9 ind./m³、69.1 ind./m³和35.4 ind./m³。2017年最低,为14.9 ind./m³。通过小型水母丰度与环境因子之间的相关性分析,结果显示:温度、盐度、pH、磷酸盐、溶解氧、无机氮、悬浮物等环境因子会对秦皇岛夏季水域水母群落结构的年际间变化产生显著影响。     

Scyphomedusae in surface waters near the Oregon coast, May–August 1981

The scyphomedusae of the surface waters off Oregon and southern Washington were collected with commercial purse seines from May–August 1981. Twelve east-west transects, located from north of the Columbia River to south of Coos Bay were sampled from the 37 m isobath to distances up to 48 km from shore. Chrysaora fuscescens was the dominant species collected in each month. Maximum sampled abundances reached 18001 of medusae per 10⁵ m³. Using an estimated carbon content of 0·280% of wet weight, this medusa density was calculated to contain approximately 50 mg Cm⁻³. Seven of the 263 samples contained so many medusae that they exceeded the capacity of the sampling gear. In all months but May, when medusa densities were relatively low, the density of C. fuscescens was greatest closest to shore and decreased rapidly offshore. Mean umbrella diameter increased from 8·6 cm in May to 18·5 cm in August, while the largest specimens increased from 19 cm in May to 37 cm in August. Aurelia aurtia, Cyanea capillata and Phacellophora camtschatica were also collected, but were much less abundant than C. fuscescens. The relative abundance of C. fuscescens was compared with the maximum abundance of copepods off the Oregon coast, and the hydrographic features influencing medusa distribution patterns are discussed.     

Estimation of the minimum food requirement using the respiration rate of medusa of Aurelia aurita in Sihwa Lake

We examined the respiration rate of Aurelia aurita medusae at 20 °C and 28 °C to evaluate minimum metabolic demands of medusae population in Sihwa Lake, Korea during summer. While weight specific respiration rates of medusae were constant and irrespective to the wet weight (8?C220 g), they significantly varied in respect to temperatures (p<0.001, 0.11±0.03 mg C g^?1 of medusa d^?1 at 20°C and 0.28±0.11 mg C g^?1 of medusa d^?1 at 28 °C in average, where Q ₁₀ value was 2.62). The respiration rate of medusae was defined as a function of temperature (T, °C) and body weight (W, g) according to the equation, R=0.13×2.62^(T-20)/10 W ^0.93. Population minimum food requirement (PMFR) was estimated from the respiration rate as 15.06 and 4.86 mg C m^?3 d^?1 in June and July, respectively. During this period, increase in bell diameter and wet weight was not significant (p=1 in the both), suggesting that the estimated PMFR closely represented the actual food consumption in the field. From July to August, medusae grew significantly at 0.052 d-1, thus the amount of food ingested by medusae population in situ was likely to exceed the PMFR (1.27 mg C m^?3 d^?1) during the period. In conclusion, the medusae population of higher density during June and July had limited amount of food, while those of lower in July and August ingested enough food for growth.     

Excretion and respiration rates of the scyphomedusa <Emphasis Type="Italic">Aurelia aurita</Emphasis> from the Inland Sea of Japan

We measured the ammonium excretion, phosphate excretion and respiration rates of the scyphomedusa Aurelia aurita from Ondo Strait, in the central part of the Inland Sea of Japan, at 28 and 20°C. The rates measured at 28°C were converted to those at 20°C using the Q₁₀ values, i.e. 1.56, 1.57 and 2.80, for ammonium excretion, phosphate excretion and respiration rates, respectively. The composite relationships between metabolic rates and wet weight of a medusa (WW, g, range 11–1330 g) at 20°C were expressed by the following allometric equations. For ammonium excretion rate (N, μmoles N medusa⁻¹d⁻¹): N = 0.497WW ^1.09, phosphate excretion rate (P, μmoles P medusa⁻¹d⁻¹): P = 0.453WW ^0.84, and respiration rate (R, μmoles O₂ medusa⁻¹d⁻¹): R = 96.9WW ^1.06. Mean O:N ratios (i.e. atomic ratios of 16.9 and 11.0 at 28 and 20°C, respectively) indicated that the metabolism of A. aurita medusae was protein-dominated. These metabolic parameters enabled us to estimate the nitrogen and phosphorus regeneration rates of an A. aurita medusa population typical of early summer in the Ondo Strait (means of water temperature, medusa individual weight and population biomass: 20°C, 200 g WW and 50.8 g WW m⁻³, respectively). Regenerated nitrogen and phosphorus were equivalent to 10.0 and 21.6% of phytoplankton uptake rates, respectively, nearly twice that estimated for mesozooplankton, demonstrating that A. aurita medusae are key components of the plankton community, influencing the trophic and nutrient dynamics in the Ondo Strait during early summer.     

辽东湾北部近海大型水母数量分布和温度盐度特征

通过2009-2011年5月下旬-7月下旬辽东湾北部近海10m等深线内的大型水母调查数据,分析了辽东湾北部近海近三年中大型水母资源状况,并探讨了辽东湾大型水母的生态类型。结果显示:辽东湾北部近海大型水母种类主要有海蜇(Rhopilema esculentum)、沙蜇(Nemopilema nomurai)、白色霞水母(Cyanea nozakii)、海月水母(Aurelia sp.1),海蜇和沙蜇是优势种。海蜇幼水母阶段主要集中分布在5m等深线以内的近岸河口水域,随着个体增大有略向深水或密度较小的水域扩散的趋势,仍主要分布在5m等深线两侧水域,属于高温低盐种类。6月份调查海区中发现大量的沙蜇幼水母,随着沙蜇个体增大,7月份调查海区中沙蜇数量大幅度减少。辽东湾海月水母在南部海域出现较多,2010、2011年在北部近海部分海域出现。白色霞水母近几年来辽东湾出现较少,栖息在盐度较高的水域。辽东湾各种大型水母中,沙蜇的生长速度最快。辽东湾海蜇幼水母、沙蜇幼水母的海区出现时间要晚于黄、东海。     

Groupers of the World: A Field and Market Guide

The diet of Chrysaora hysoscella was investigated from 55 specimens caught near the surface throughout 24h in Walvis Bay Lagoon, Namibia, during September 2003. The diet was diverse, ranging from dinoflagellates to carideans, and included abundant benthic species (adults and larvae). There was no clear overall relationship between medusa size and either the number or type of prey ingested, although aspects of both measures were significantly related to size when analyses were confined to the nocturnally collected data. Whereas there was a significant difference in the diet of medusae collected by day and night, principally because of an increase in the abundance of benthic prey items, it was not possible to partition this between the vertical migration of predator (downwards) or prey (upwards) owing to a lack of information on the ambient prey environment. Regardless, the abundance of benthic prey in the diet could help explain the predominance of medusae off Namibia, where there has been an increased flow of surface production to the benthos since the collapse of the pelagic fisheries.     

Vertical Distribution of Gelatinous Macroplankton in the North Pacific Observed by Manned Submersibles Mir-1 and Mir-2

The vertical distribution of several medusa species in the Kurile-Kamtchatka region of the Pacific Ocean is described. Animals were observed in the light cone from deep-sea submersibles Mir-1 and Mir-2 throughout the water column, from the surface to 5000–6000 m at four different sites. Bathy- and abyssopelagic species are noted along with the species living in an extremely wide depth range. A faunistic border is revealed at a depth of 3000 m. The contribution of gelatinous animals (medusae, siphonophores, salps) to the total deep-sea plankton biomass was estimated using a wire reference cube during nine dives in the highly productive areas of the northwest Pacific, eastern Pacific (California, Costa-Rica Dome), and subtropical oligotrophic areas. This revised version was published online in August 2006 with corrections to the Cover Date.     

Population succession and feeding of scyphomedusae, Aurelia aurita, in a eutrophic tropical lagoon in Taiwan

Seasonal dynamics and feeding of scyphomedusae, Aurelia aurita, were investigated monthly from 1999 to 2002 in relation to environmental conditions in Tapong Bay, a eutrophic tropical lagoon in southwestern Taiwan. Medusae appeared throughout the year but exhibited seasonal dynamics that were correlated with hydrographic features in the bay. Most ephyrae of A. aurita occurred mainly in the lower flushed and eutrophic inner bay, and during the cold, dry season between November and February. They grew to young medusae with a maximum abundance in spring (March–May), but their numbers abruptly decreased during the warm and rainy summer season in June–September. The remaining medusae then grew rapidly to a maximal size of 29 cm. Mature females spawned in the following autumn when precipitation decreased but zooplankton food was still abundant. These mature individuals decreased in size after spawning and in winter. Gut content analysis revealed that A. aurita fed mainly on copepods and copepod nauplii and less on bivalve larvae and fish eggs. Prey selectivity indices indicated that larger medusae selected positively for copepods while small size medusae preferred copepod nauplii. The overall feeding effect of A. aurita on the standing stock of zooplankton was significant (27%) in the bay. Our results suggest that tidal flow and dense oyster culture pens were the two most important factors influencing the spatial distribution pattern of A. aurita in the bay, while precipitation affected the population abundance seasonally; decreasing water temperature coincided with the mass release of ephyra in late autumn and winter.     

水母伞径和饵料密度对海月水母(Aurelia sp.1)捕食率的影响

海月水母在全球范围内大量暴发,严重危害海洋生态系统的健康以及鱼类资源的可持续利用。本文以卤虫无节幼体为饵料,初步研究了水母伞径和饵料密度对海月水母个体捕食率的影响以及海月水母的昼夜捕食节律。研究结果表明,海月水母的伞径对其捕食率的影响极显著(P<0.01),在1—8cm范围内,随着伞径的增加个体捕食率线性增加,两者之间的关系式为y=0.044x+0.125(R2=0.9036)。饵料密度对海月水母捕食率的影响显著(P<0.05),在0.25—26.11mgC/L范围内,随饵料密度的增加个体捕食率呈线性增加趋势,关系式为y=0.508x(R2=0.958)。在饵料充足时,海月水母没有昼夜捕食节律。在高饵料密度下海月水母出现过剩捕食,但是捕食行为依然活跃。上述结果既为量化评估海月水母对浮游动物群体的捕食压力提供了基础参数,同时水母过剩捕食行为说明依据生物量和代谢率的推算结果可能低估自然海域水母队浮游动物的捕食压力。     

Adaptive behaviours of the jellyfish Aurelia labiata in Roscoe Bay on the west coast of Canada

Four behaviours of mature Aurelia labiata medusae (Scyphozoa) were observed. Touching the manubrium with a soft, hollow, silicone rubber ball or a foam rubber ball caused medusae at a depth of 1 m to swim to the surface. Dense aggregations of medusae did not form within 5 m of rock walls. Medusae did not swim into water with salinity < 20 parts per thousand. Sunlight-stimulated directional swimming was to the west. These behaviours add to a growing list of adaptive behaviours of Aurelia labiata medusae.     

基于脂肪酸标记法和碳氮稳定同位素比值法的东海水母常见种的食性分析

采用脂肪酸标记法和碳氮稳定同位素比值法研究了东海6个水母常见种的食性。结果表明,6种水母的总脂肪酸含量都不高,说明作为饵料,水母不能够给捕食者提供较多的脂类营养物质。蝶水母(Ocyropsis crystallina)、瓜水母(Bero cucumis)和四叶小舌水母(Liriope tetraphylla)的脂肪酸组成较为相近,它们更多地通过捕食食物链获得有机质。同时,这几种小型水母摄食浮游植物(主要是硅藻和甲藻)比其它几种水母多;另外,它们对植食性桡足类也有一定的摄食。4月份墨绿多管水母(Aequorea coerulescens)主要通过腐生食物链获取有机质;另外,其对植食性桡足类也有一定的摄食。双生水母(Diphyidae spp.)参与腐生食物链也较多;另外,20:1+22:1含量较低指示了其对植食性桡足类几乎不摄食。蝶水母、瓜水母、四叶小舌水母和沙海蜇(Nemopilema nomurai)的δ13C更接近于陆源的C4植物的δ13C,说明其受陆源影响较大。δ15N特征结果表明,蝶水母、瓜水母和四叶小舌水母(Liriope tetraphylla)在浮游食物网中均处于较高营养级,沙海蜇虽个体较大,但由于其摄食器官较小,故其与这3种小型水母的营养地位相近。并且相对于其它几种水母,沙海蜇细菌脂肪酸标记更为明显。     

The relationship among environmental variables,jellyfish and non‐gelatinous zooplankton: A case study in the north of the Gulf of Oman

Processes underlying the temporal and spatial variations observed in the distribution of jellyfish and non‐gelatinous zooplankton in the Gulf of Oman are not well understood. This information gap is clearly a major issue in controlling the harmful blooms of jellyfish and non‐gelatinous zooplankton. Samples of jellyfish and non‐gelatinous zooplankton were collected from six stations in Chabahar Bay and three stations in Pozm Bay within four seasons. At each station, environmental variables were also recorded from bottom and surface water. A total of 83 individuals of medusae representing four species of Scyphozoa (i.e., Cyanea nozakii, Chrysaora sp., Pelagia noctiluca, Catostylus tagi) and species of Hydrozoa (i.e., Diphyes sp., Rhacostoma sp., Aequorea spp.) were observed in the study area. A total of 70,727.25 individuals/m^?3 of non‐gelatinous zooplankton dominated by copepods and cladocerans were collected in nine stations within the four seasons. The results of a RELATE analysis yielded no significant association between species composition for jellyfish and non‐gelatinous zooplankton. Among environmental variables, water transparency, nitrite concentration, water depth and temperature were better associated with the total variation in jellyfish species composition than with that of non‐gelatinous zooplankton. Dissolved oxygen, pH, and phosphate concentration were significant environmental variables associated with the variation in the spatial and temporal distribution patterns of non‐gelatinous zooplankton assemblages. Although some jellyfish species (i.e., Rhacostoma sp., Pelagia noctiluca, Catostylus tagi) occur independently of non‐gelatinous zooplankton assemblages, other jellyfish (i.e., Chrysaora sp., Aequorea spp., Cyanea nozakii, Diphyes sp.) are strongly correlated with non‐gelatinous zooplankton assemblages.     

Craspedacusta sowerbyi Lankester (Coelenterata: Limnomedusae) IN New Zealand lakes

A sudden infestation of medusae, identified as Craspedacusta sowerbyi Lankester, occurred in Lake Maraetai, North Island, New Zealand, during the last week of January 1970. Previous records of immature medusae in North Island lakes and of hydroilds in a Dunedin aquarium probably refer to the same species. High water temperatures favoured development of the medusae, but their effect on the ecology of the lake was probably negligible.     

夏季长江口及邻近海域水母类生态特征研究

利用2003年6月和2006年6月在长江口及邻近海域进行的两次大面调查所采集的浮游动物网采样品,对长江口及邻近海域水母类的种类组成、优势种、数量分布及生态类群等进行了探讨。结果表明:研究水域共记录水母类77种,其中水螅水母60种,管水母12种,钵水母1种,栉水母4种。优势种有:五角水母(Muggiaea atlantica),双生水母(Diphyes chamissonis),拟细浅室水母(Lensia subti-loides),四叶小舌水母(Liriope tetraphylla),两手筐水母(Solmundella bitentachlata),嵊山秀氏水母(Sugiura chengshanense)和瓜水母(Bere cucumis)等。其中水螅水母类的优势种存在较大的年际变化,2003年为嵊山秀氏水母,2006年为四叶小舌水母和两手筐水母。研究水域内水母类平面分布不均匀,2003年平均丰度为13.3个/m3,除在长江口外存在一个由河口低盐种贝氏拟线水母(Nemopsis bachei)大量聚集形成的高值区外,在舟山群岛南部还存在一个密集中心;2006年水母类丰度略有上升,平均丰度为16.0个/m3,与2003年相比,其密集中心向东北部偏移。2006年6月研究海域温、盐较2003年同期均大幅升高是造成两航次优势种类更替及水母类分布变化的主要原因。     

Predation by jellyfish on large and emergent zooplankton: Implications for benthic–pelagic coupling

Stable carbon isotopes were used to determine the contribution of emergent demersal zooplankton to the diet of the scyphozoan jellyfish Catostylus mosaicus at Smiths Lake, New South Wales, Australia. A preliminary study in 2004 indicated that there was no difference in the δ¹³C of ectodermal tissue and mesoglea of the medusae. In 2005, medusae and zooplankton present during the day and night were sampled and isotopic signatures were modelled using IsoSource. Modelling indicated that: (1) mollusc veligers and copepods sampled during the day contributed <13% of the carbon to the jellyfish; (2) copepods sampled at night contributed up to 25%; and (3) the large, emergent decapod Lucifer sp. contributed 88–94%. We hypothesised, therefore, that medusae derive most of their carbon from emergent species of zooplankton. In 2006, sampling done in 2005 was repeated three times over a period of 4 weeks to measure short-term temporal variation in isotopic signatures of medusae and zooplankton, and emergent demersal zooplankton was specifically sampled using emergence traps. Short-term temporal variation in isotopic signatures was observed for some taxa, however, actual variations were small (<1.5‰) and the values of medusae and zooplankton remained consistent relative to each other. IsoSource modelling revealed that mysid shrimp and emergent copepods together contributed 79–100% of the carbon to the jellyfish, and that the maximum possible contribution of daytime copepods and molluscs was only 22%. Jellyfish apparently derive most of their carbon from emergent zooplankton and by capturing small numbers of relatively large taxa, such as Lucifer sp. or mysid shrimp. Small but abundantly captured zooplankton (such as mollusc veligers) contribute only minor amounts of carbon. Jellyfish have a major role in the transfer of carbon between benthic and pelagic food webs in coastal systems.     

Description of feeding apparatus and mechanism innemopilema nomurai kishinouye (scyphozoa: rhizostomeae)

Feeding apparatus, mechanism and passage of ingested prey were described forNemopilema nomurai (Scyphozoa: Rhizostomeae).N. nomurai medusae without central mouths have developed complicated canal systems connecting the tip of the tentacle and oral arm to the gut cavity. The number of junctions in the canal system increases with the bell diameter. The prey is gathered by paralyzing nematocyst at the tentacles and by adhering cirri at the oral arms and scapulets. They are engulfed into the terminal pore located at the oral arms and scapulets, and entered into the gut cavity via the canal system. The estimated digestion time is 1 hour and 20 min. The diameter of terminal pore is always about 1 mm, implying that they could not eat prey larger than that pore size. On the other hand, ephyrae have central mouths and could swallow prey as large as adults could. Exploitation of the same size of food by adult and ephyra implies thatN. nomurai can affect seriously the whole food web, massively ingesting micro-and mesozoopl a n k t o n and cutting the energy transfer toward the higher level of carnivores.     

基于18S rDNA条形码技术的珊瑚礁区塔形马蹄螺(Tectus pyramis)食性分析

塔形马蹄螺(Tectuspyramis)是一种暖水性较强的海洋贝类,也是一种重要的礁栖生物,研究其自然环境中的食物组成对于认识其生态功能具有重要意义,但由于缺少直接的食物组成信息,对其食性和生态功能定位尚不明确。本研究于2017年春季在南沙珊瑚礁区采集了塔形马蹄螺样品,以18S rDNA可变区(V4)序列为靶标,用高通量测序技术分析了其现场食物组成。共测得41个OTU,分属11个门类,包括节肢动物门(Arthropoda)、子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、丝足虫门(Cercozoa)、刺胞动物门(Cnidaria)、Stramenopiles(不等鞭毛类)、网粘菌门(Labyrinthulomycota)、软体动物门(Mollusca)、多孔动物门(Porifera)、甲藻门(Pyrrophyta)、捕虫霉亚门(Zoopagomycota)。与以往研究不同的是,本研究发现塔形马蹄螺消化道中存在大量沉积物碎屑,其中有孔虫、真菌、后生动物是最重要的类群,占食物序列组成的99.76%,它们主要存在于海洋沉积物、有机碎屑和礁石表生藻类基质(Epilithic algal matrix, EAM)中。研究结果揭示了塔形马蹄螺的食物主要来源于EAM中的小型生物和碎屑以及珊瑚礁石上的有害生物,推测塔形马蹄螺属于沉积物碎屑食性生物,可能在清除珊瑚表面藻类基质、促进珊瑚幼体附着过程中发挥一定的作用,对于维护珊瑚生态系统的健康和稳定具有积极意义。     

Discovery of Cladonema multiramosum sp. nov. (Cnidaria: Hy-drozoa: Cladonematidae) using DNA barcoding and life cycle analyses

In contrast to typical planktonic hydromedusae, Cladonema medusae are mostly benthic, with specialised adhesive branches to adhere to the substrate. In this study, a Cladonema species discovered in a laboratory aquarium in Fuzhou, China, was confirmed as a new species, based on morphological and molecular analyses.The species was named Cladonema multiramosum sp. nov. Its medusa is distinct from that of congeners possessing substantially more adhesive branches(8–24, rarely 5–7), and tiny branches...     

Clearance rates of ephyrae and small medusae of the common jellyfish Aurelia aurita offered different types of prey

Prey selection and knowledge of the amounts of water processed by the early stages of the common jellyfish Aurelia aurita may at certain times of the year be crucial for understanding the plankton dynamics in marine ecosystems with mass occurrences of this jellyfish. In the present study we used two different methods (“clearance method” and “ingestion-rate method”) to estimate the amount of water cleared per unit of time of different types and sizes of prey organisms offered to A. aurita ephyrae and small medusae. The mean clearance rates of medusae, estimated with Artemia sp. nauplii as prey by both methods, agreed well, namely 3.8 ± 1.4 l h^? 1 by the clearance method and 3.2 ± 1.1 l h^? 1 by the ingestion-rate method. Both methods showed that copepods (nauplii and adults) and mussel veligers are captured with considerably lower efficiency, 22 to 37% and 14 to 30%, respectively, than Artemia salina nauplii. By contrast, the water processing rates of ephyrae measured by the clearance method with A. salina nauplii as prey were 3 to 5 times lower than those measured by the ingestion-rate method. This indicates that the prerequisite of full mixing for using the clearance method may not have been fulfilled in the ephyrae experiments. The study demonstrates that the predation impact of the young stages of A. aurita is strongly dependent on its developmental stage (ephyra versus medusa), and the types and sizes of prey organisms. The estimated prey-digestion time of 1.3 h in a steady-state feeding experiment with constant prey concentration supports the reliability of the ingestion-rate method, which eliminates the negative “container effects” of the clearance method, and it seems to be useful in future jellyfish studies, especially on small species/younger stages in which both type and number of prey can be easily and precisely assessed.     

半滑舌鳎(Cynoglossus semilaevis)摄食行为感觉作用的研究

采用实验室内鱼类行为学研究方法对半滑舌鳎的摄食行为进行研究。结果表明,嗅觉、味觉和侧线在半滑舌鳎的摄食中具有重要作用,视觉在摄食中的作用没有被发现。侧线在摄食中作用主要体现在头部侧线,躯干部侧线对侧面刺激有一定的攻击行为,但行为发生率与头部各部位受刺激时产生的行为发生率相比较低,且差异显著(P<0.05);躯干部对上部刺激仅发生警戒行为,没有观察到攻击行为。侧线和嗅觉在摄食中的作用大小比较差异显著(P<0.05),侧线的作用优于嗅觉。口咽腔对味道和硬度都有作用且对二者的敏感程度差异显著(P<0.05),对味道更为敏感。