海洋围隔生态系中浮游动物的研究

2002-05-20-26在东海进行小尺度船基浮游生物生态系围隔实验,研究浮游动物的群落结构、组成与环境之间的关系,探讨了优势种群的自然繁殖发育期。结果表明,浮游动物的种类组成较简单,优势种明显。浮游动物生物量、丰度及优势种群丰度三者的变化呈逐渐增加趋势。在实验期的1～5d,小拟哲水蚤的无节幼虫和早期幼体占绝对优势,该自然种群的丰度不断增加;随时间推移,无节幼虫逐渐发育为桡足幼体,而后又逐渐发育为成体。因此,本次实验期是实验海区优势种小拟哲水蚤种群的自然繁殖发育盛期。     

秋季南黄海浮游动物分布及其影响因素

基于2007年秋季在南黄海（32°20'~37°00'N;124°E以西）进行的浮游动物及环境因子大面调查;分析了秋季南黄海浮游动物种类组成、分布特征及其影响因素;主要结果如下:共鉴定浮游动物113种（不包括25种浮游幼体）;中华哲水蚤（Calanus sinicus）、强壮滨箭虫（Aidanosagitta crassa）、磷虾幼体（Euphausia larvae）和小齿海樽（Doliolum denticulatum）是秋季优势种;浮游动物丰度为（156.37±12.04）ind/m3;生物量为（172.57±10.41）mg/m3;与历史调查数据相比;本航次浮游动物丰度和生物量相对处于较高水平;磷虾幼体分布趋势与中华假磷虾（Psudeuphausia sinica）一致;说明秋季是中华假磷虾种群的一个重要的补充时期;小齿海樽在南黄海的大量出现系自身种群补充的结果;精致真刺水蚤（Euchaeta concinna）和肥胖软箭虫（Flaccisagitta enflata）主要分布在深水区;在近岸海区很少出现。中华哲水蚤、强壮滨箭虫丰度高值区倾向分布于海洋锋附近;进一步佐证了海洋锋对浮游动物的积聚作用。     

中华哲水蚤幼体的发育

中华哲水蚤(Calanus sinicus Brodsky)主要分布于北太平洋亚洲大陆沿岸水域(44°—21°N),是我国近海浮游桡足类优势种之一。关于它的幼体发育尚未见报道。迄今已知4种哲水蚤——飞马哲水蚤[C.finmarchicus(Gunderus)]、海哥兰哲水蚤[C.helgolandicus(Claus)]、极北哲水蚤(C.hyperboreus Krφyer)和寡毛哲水蚤(C.tonsus Brady)的幼体发育研究颇为详尽。本文目的在于查明中华哲水蚤幼体阶段各发育期的外部形态,为探讨它的数量变动、产量和分布等问题提供基本资料。     

夏季莱州湾浮游动物群落特征

根据2009 年8 月监测资料, 研究了夏季莱州湾海域浮游动物种类组成、生态分布、群落结构及其环境影响因子。共记录包括浮游幼虫在内的浮游动物38 种(类), 优势种类为长尾类幼虫、强壮箭虫、短尾类溞状幼虫及太平洋纺锤水蚤等。浮游动物丰度101.3～3620.0 个/m³, 平均602.8 个/m³, 丰度平面分布呈现湾西部高, 向中东部逐渐降低趋势; 长尾类幼虫、强壮箭虫、短尾类溞状幼虫出现频率100%,太平洋纺锤水蚤出现频率40.9%; 长尾类幼虫丰度7.8～1747.9 个/m³, 平均96.3 个/m³, 高值区分布于莱州湾西部黄河口以南近岸水域; 强壮箭虫丰度2.5～747.8 个/m³, 平均85.4 个/m³, 偏离近岸趋深水、低温区分布; 短尾类溞状幼虫丰度3.3～271.7 个/m³, 平均20.5 个/m³, 主要分布于莱州湾南部近岸水域; 太平洋纺锤水蚤丰度0～968.3 个/m³, 平均29.0 个/m³, 密集分布区在莱州湾西南部小清河外近岸低盐水域。浮游动物丰度分布与NO₂-N、DO、COD 及NO₃-N 呈显著正相关关系, 与盐度呈显著负相关关系(P＜0.01)。等级聚类分析(CLUSTER)将莱州湾的浮游动物分为湾西部和湾中东部两个群落。相比于湾中东部群落, 湾西部群落占据着莱州湾西部近岸较狭窄的地理范围, 其所在水域水浅, 盐度低, 无机氮、活性磷酸盐、叶绿素a、浮游动物丰度高及物种多样性高, 群落内生物相似性弱。     

莱州湾中华哲水蚤种群结构及丰度分布

中华哲水蚤是中国近海生态系统浮游动物关键种之一。它是莱州湾内唯一成体大于2mm的桡足类优势种,是仔鱼向幼鱼转换过程中重要的饵料来源。本研究基于2011年5月至2012年4月(除12月和翌年1—2月为冰期外)逐月采集的浮游动物样品,进行了莱州湾中华哲水蚤种群中桡足幼体和成体的生态分布分析。结果表明:在所有调查月份中,中华哲水蚤桡足幼体CI—CV和成体都出现了。桡足期个体的总丰度和生物量季节变化呈单峰型,高峰期出现在5—6月。月均生物量为2.91mg C/m~3,丰度为7ind/m~3;日生产力和年生产力估算值分别为0.74mg C/(m~3·d)和266mg C/(m~3·a)。各调查月份中,CIV和CV对总丰度的贡献比例最高;4月和10月以早期桡足幼体CI—CIII居多,8—9月和11月以成体占绝对优势;其他月以后期桡足幼体(CIV和CV)丰度值相对较高。成体中,雌体较多;雌/雄性比值介于0.86—6.46,在11月最高,10月最低。各发育期的前体长月均值在8—9月最低,4月最高;其季节变化与水温呈负相关。丰度分布由莱州湾湾口东侧向湾内逐渐减少;丰度高值区(100ind/m~3)集中出现于5—6月的表层水温介于15—25°C、盐度高于31—32的站位。     

夏季南黄海浮游甲壳动物死体比例的初步研究

浮游动物死体是海洋沉降碳通量的重要组成部分,研究浮游动物死体对于准确评估特定海区生物泵碳通量具有十分重要的意义。为了解夏季南黄海浮游甲壳动物在自然海区的死亡情况,采用2019年7~8月在南黄海获取的浮游动物样品,使用中性红染色法分析了浮游甲壳动物死体的平面分布及其受控环境因素。结果表明,夏季南黄海浮游甲壳动物平均丰度为(1 378.3±929.84) ind./m³,其死体比例在5.0%~68.8%之间,平均为33.3%±16.6%。桡足类是浮游甲壳动物的主要类群,平均丰度为(1 202.9±937.4) ind./m³,死体比例在3.6%~69.7%之间,平均为38.6%±17.0%,与全球海域浮游桡足类的平均死体比例相当。不同浮游甲壳动物优势种的死体比例存在差异。其中,拟长腹剑水蚤(Oithona similis)死体比例最高(62.0%),鸟喙尖头溞(Penilia avirostris)最低(17.9%)。与环境因子的相关性分析结果表明,海水温度和盐度是影响夏季南黄海浮游甲壳动物死体比例的主要影响因子。小拟哲水蚤(Paracalanus parvus)死体比例和表层温度显著正相关,拟长腹剑水蚤和近缘大眼剑水蚤(Corycaeus affinis)的死体比例与表底温差具有显著的正相关;而表层盐度与克氏纺锤水蚤(Acartia clausi)的死体比例存在正相关关系。该研究结果可为深入认识南黄海海洋生态动力学过程和海洋碳通量等相关研究提供重要的参考资料。     

2010年秋季黄河口及其邻近海域中小型浮游动物的群落特征

为掌握黄河口邻近水域中小型浮游动物的现状并弥补此类重要浮游生物类群在以往调查研究中的欠缺, 于2010 年9 月在黄河口及其邻近海域用浅水Ⅱ型浮游生物网采集了浮游动物样品, 分析了中小型浮游动物的种类组成、丰度分布、优势种、生物多样性及群落结构。本次调查共鉴定浮游动物成体48 种, 浮游幼虫21 类, 桡足类和水螅水母为最主要的浮游动物类群, 分别占浮游动物成体种数的37.5%和20.8%。浮游动物丰度为2 300.1～266 232.0 个/m³, 平均丰度为37 074.3 个/m³。优势种(类)8种, 分别为夜光虫、强额拟哲水蚤、小拟哲水蚤、背针胸刺水蚤、异体住囊虫、桡足类无节幼虫、双壳类幼体以及腹足类幼体, 其中夜光虫为研究水域最主要优势种。对各站位物种组成和丰度进行分析,调查水域中小型浮游动物可划分为4 个组群, 各组群的分布格局受到水温、盐度和海流的共同影响。该研究为此水域生态系统的长期变化研究提供了重要基础资料和参考依据。     

莱州湾拟哲水蚤Paracalanus sp.发育期丰度组成和个体大小季节变化

拟哲水蚤是莱州湾桡足类中周年出现的优势种;是上层鱼类幼鱼早期开口饵料的重要贡献者;掌握其种群动态分布特点;有利于了解湾内生物环境状况、次级生产力生产水平。基于2011年5月至20 12年4月采集的浮游生物资料的分析结果显示;莱州湾拟哲水蚤的发育期丰度组成和个体大小均表现了明显的季节变化。调查季节中;4-6月以成体居多;其他季节以桡足幼体CⅢ-CⅤ较多;其中10-11月和3月主要由后期桡足幼体CⅣ和CⅤ期构成。成体中以雌体为主导;雌/雄比介于1.46~9.62;该比值在3-4月最低;10-11月最高。拟哲水蚤各期桡足幼体和成体个体大小以4-5月最大、8月最小;并与水温表现出明显的负相关。拟哲水蚤桡足幼体和成体的总生物量月变化与丰度变化相同;即以8月值最高;3-5月值最低;月均值为2.69 mg/m3（以碳计）;日生产力估算值为0.74 mg/（m3·d）（以碳计）。由上述结果;推测莱州湾拟哲水蚤的种群结构周年变化主要可分3个阶段;4-6月是莱州湾拟哲水蚤开始繁殖期;7-8月为种群数量快速增长期;9月之后为种群增长相对停滞期。     

黄海小拟哲水蚤(Paracalanus parvus)丰度的季节变化

根据2001年3、5、6、7、8、11月黄海6个航次的大容量采水器(59L)中浮游动物的样品资料,对小拟哲水蚤无节幼体及该种桡足幼体和成体丰度的时空分布格局进行了研究。结果表明,小拟哲水蚤桡足幼体和成体3月份在整个黄海测区内的丰度较低;5月份除山东半岛南岸三个高值站位,外海相对比近岸高;6、7月份的丰度水平最高,7月份航次中,丰度最高的站位可达10555ind/m3,整个测区内,海州湾内侧高于外侧;8月份,测区内的丰度分布相对均匀,丰度较低;11月份,测区小拟哲水蚤的分布相对也比较均匀。小拟哲水蚤无节幼体的丰度在黄海测区内的分布格局与该种桡足幼体及成体丰度的分布格局在3、5、6、7月份比较吻合,在8、11月份吻合程度较差。不同月份小拟哲水蚤的分布与温度、盐度、叶绿素a的关系不尽相同;其受温度的影响相对较大,受盐度、叶绿素a影响较小。     

南极夏季南设得兰群岛周边海域浮游动物优势种群的分布、丰度及种群结构分析

根据2013/2014年夏季在南极南设得兰群岛周边海域使用北太平洋网采样品及同步环境调查资料,分析了南极大磷虾(Euphausia superba)、拟长臂樱磷虾(Thysanoessa macrura)、尖角似哲水蚤(Calanoides acutus)和近缘哲水蚤(Calanus propinquus)这四种优势浮游动物的丰度和分布特征。结果表明,南极大磷虾和拟长臂樱磷虾在南设得兰海域均有较为广泛的分布,其中南极大磷虾丰度较高,且它们的水平分布存在一定程度的空间分离。在研究海域东部的南奥克尼群岛(South Orkneys)邻近海域发现了大量的南极大磷虾原蚤状C期幼体,表明大磷虾曾于1月中上旬左右产卵繁殖。研究海域的东部南极大磷虾种群结构以幼体前期为主,而西部的种群结构则以幼体后期、未成体和成体为主。尖角似哲水蚤和近缘哲水蚤的空间分布也较为广泛,且两者分布基本一致。东部南奥克尼群岛临近海域的浮游植物浓度较低,这可能是大量南极大磷虾幼体和桡足类摄食活动的结果。     

Species Composition and Distribution of Zooplankton from Northeastern Sakhalin Shelf (Sea of Okhotsk)

The species composition, density, biomass, and distribution of zooplankton of the northeastern Sakhalin shelf, Sea of Okhotsk (Chaivo, Pil’tunskii, and Morskoi regions) were studied in October 2014. Zooplankton was represented by 15 taxonomic groups, which were dominated by Copepoda (13 species). The average density and biomass was highest in the Chaivo region (14112 ± 4322 ind./m³, 395 ± 107 mg/m³) and in the Pil’tunskii region (16692 ± 10707 ind./m³, 346 ± 233 mg/m³); the abundance of detected taxonomic groups was minimal (8–12). The average density and biomass of zooplankton was up to 4304 ± 2441 ind./m³, 133 ± 77 mg/m³ in the Morskoi region and increased with depth; the abundance of taxa was maximum (15). Four species of copepods made up the majority of the density and biomass of zooplankton: Acartia hudsonica, Eurytemora herdmani, Pseudocalanus newmani, and Oithona similis. In the Chaivo region, species of the genera Acartia, Eurytemora, and Oithona dominated and subdominated; in Pil’tunskii region, species of the genera Acartia and Oithona dominated and subdominated; and in the Morskoi region, species of the genera Oithona, Pseudocalanus, and Acartia dominated and subdominated.     

春、秋季南黄海浮游纤毛虫丰度及生物量的分布差异

Seasonal variation of marine plankton spatial distribution is important in understanding the biological processes in the ocean.In this study,we studied spatial distribution of planktonic ciliate abundance and biomass in the central deep area(station depth greater than 60 m) and the coastal shallow area(station depth less than 60 m) of the southern Yellow Sea(32°–36.5°N,121°–125°E) in spring(April) and autumn(October–November) of 2006.Our results showed that both ciliate abundance and biomass in the surface waters were higher in spring((1 490±2 336)ind./L;(4.11±7.81) μg/L) than in autumn((972±823) ind./L;(1.11±1.18) μg/L,calculated by carbon).Ciliate abundance and biomass in the surface waters of the coastal shallow area were similar in spring and autumn.However,in the central deep area,those values were much higher in spring((1 878±2 893) ind./L;(5.99±10.10)μg/L) than in autumn((738±373) ind./L;(0.74±0.76) μg/L).High values of ciliate abundance and biomass occurred in the central deep area in spring and in the coastal shallow area in autumn.Mixotrophic ciliate Laboea strobila was abundant in the central deep area in spring,when a phytoplankton bloom occurred.However,in autumn,L.strobila was abundant in the coastal shallow area.Boreal tintinnid Ptychocyli obtusa was found in spring.Both L.strobila and P.obtusa were concentrated in the surface waters when their abundance was more than 1 000 ind./L.Peaks of these species were in the subsurface waters when their abundance was less than 400 ind./L.This study showed that both high abundance and biomass of ciliates occurred in different areas in southern Yellow Sea seasonally.     

Grazing Impact of the Copepod <Emphasis Type="Italic">Calanus sinicus</Emphasis> on Phytoplankton in the Northern East China Sea in Late Spring

We investigated the feeding habits of Calanus sinicus during its four developmental stages as copepodite 4 (CIV), copepodite 5 (CV), adult males and females in early June 2015 at 12 sampling stations along the southern coast of Korea to the northern East China Sea, to better understand the role of C. sinicus in controlling phytoplankton stocks. Ingestion rate, daily ration as body carbon, population ingestion rate, and grazing impact were estimated using the gut pigment method. The mean biomass of CVs was the greatest (13.5 mg C m^–3) and that of adult males was the lowest (0.7 mg C m^–3). The ingestion rate per C. sinicus individual tended to increase with developmental stage, with the highest rate in adult females (519 ng chl ind^–1 d^–1) and the lowest rate in CIVs (305 ng chl ind^–1 d^–1). A significant correlation was found between ingestion rate and temperature, but not salinity or chlorophyll-a concentration. The daily ration of C. sinicus as body carbon significantly decreased with increased body weight, with the highest value found in CIVs (66.4%) and the lowest value in adult males (30%). Despite the high ingestion rate of the adults, the mean grazing impact of C. sinicus on phytoplankton biomass, in terms of chlorophyll-a concentration, was the highest in CVs (2.6%), followed by CIVs and adult females, and was the lowest in adult males (0.1%). The higher grazing impact of copepodites than adults underscores the importance of evaluating copepodite stages in the feeding studies of marine food webs.     

Structure of Mesozooplankton Communities in the Coastal Waters of Morocco

Mero- and holoplanktonic organisms from 23 large taxa have been detected in the coastal waters of Morocco. Seven Cladocera species and 164 Copepoda species were identified. Copepod fauna mostly consisted of oceanic epipelagic widely tropical species, but the constant species group (frequency of occurrence over 50%) included neritic and neritic–oceanic widely tropical species. The neritic community that formed a biotopic association with coastal upwelling waters and the distant-neritic community associated with Canary Current waters were the two major communities detected. The former community was characterized by a high abundance and biomass (5700 ind./m³ and 260 mg/m³) and predominance of neritic species. The trophic structure was dominated by thin filter feeders, mixed-food consumers, and small grabbers; the species structure was dominated by Paracalanus indicus, Acartia clausi, and Oncaea curta; the indices of species diversity (3.07 bit/ind.) and evenness (0.63) were relatively low. The latter community was characterized by low abundance and biomass (1150 ind./m³ and 90 mg/m³); variable biotopic, trophic, and species structure; and higher Shannon indices (3.99 bit/ind.) and Pielou (0.75). Seasonal variation of the abundance of organisms was not detected in the communities. Anomalous mesozooplankton states were observed in summer 1998 and winter 1998–1999.     

Assessment of the consecutive harmful dinoflagellate blooms during 2015 in the Izmit Bay (the Marmara Sea)

A series of red tides were observed during 2015 in the Izmit Bay(the Marmara Sea) which is located in the most industrialized and populated region of Turkey. Six samplings were carried out in this area following the red tides.Nitrite-N, nitrate-N, ammonia, silica and orthophosphate concentrations were analyzed spectrophotometrically.Physicochemical conditions were measured by CTD probe. Plankton quantification was performed using counting chambers under microscopes. Prorocentrum micans was the most abundant species, except on May 14,2015, when Noctiluca scintillans was dominant. The abundance of P. micans reached average 18×10~6 ind./L on May 3, 2015 in the Karamürsel station, simultaneously with elevated levels of NH_3 and o-PO_4~(3–). The sample was also abundant in dead amphipods((72±12) ind./L) that had been covered by mucilage aggregates produced by P.micans. The highest biomass(calculated by carbon) was recorded as(268±26.0) mg/L on May 14 in the Hereke station. Beside the anthropogenic wastewater discharges, unknown sources and resuspensions caused increases in nutrient levels. After long term northeaster gusts(35 km/h for 5 d) an upwelling occurred on November 6, 2015 after wind-induced sediment resuspension. Although nutrient discharges remarkably decreased over 30 years through established wastewater treatment plants, harmful phytoplankton blooms still occur. Comparing the present results with other studies in nearby Mediterranean seas reveals that the most intense harmful dinoflagellate bloom in recent years occurred in the Izmit Bay. Therefore, additional protection measures necessary for a cleaner Izmit Bay. These incidents also demonstrate that contaminants, accumulated in sediment,may have long-lasting effects on enclosed marine ecosystems.     

<Emphasis Type="Italic">In-situ</Emphasis> measured primary productivity of ice algae in Arctic sea ice floes using a new incubation method

Recent changes in climate and environmental conditions have had great negative effects such as decreasing sea ice thickness and the extent of Arctic sea ice floes that support ice-related organisms. However, limited field observations hinder the understanding of the impacts of the current changes in the previously ice-covered regions on sea ice algae and other ice-related ecosystems. Our main objective in this study was to measure recent primary production of ice algae and their relative contribution to total primary production (ice plus pelagic primary production). In-situ primary productivity experiments with a new incubation system for ice algae were conducted in 3 sea ice cores at 2 different ice camps in the northern Chukchi Sea, 2014, using a ¹³C and ¹⁵N isotope tracer technique. A new incubation system was tested for conducting primary productivity experiments on ice algae that has several advantages over previous incubation methods, enabling stable carbon and nitrogen uptake experiments on ice algae under more natural environmental conditions. The vertical C-shaped distributions of the ice algal chl-a, with elevated concentrations at the top and bottom of the sea ice were observed in all cores, which is unusual for Arctic sea ice. The mean chl-a concentration (0.05 ± 0.03 mg chl-a m^?3) and the daily carbon uptake rates (ranging from 0.55 to 2.23 mg C m^?2 d^?1) for the ice algae were much lower in this study than in previous studies in the Arctic Ocean. This is likely because of the late sampling periods and thus the substantial melting occurring. Ice algae contributed 1.5–5.7% of the total particulate organic carbon (POC) contents of the combined euphotic water columns and sea ice floes. In comparison, ice algae contributed 4.8–8.6% to the total primary production which is greater than previously reported in the Arctic Ocean. If all of the ice-associated productions were included, the contributions of the sea ice floes to the total primary production would be greater in the Arctic Ocean and their importance would be greater in the arctic marine ecosystems.     

2003年夏季西北冰洋浮游动物群落结构和地理分布研究

根据西北冰洋43个调查站位的浮游动物种类组成和数量资料,分析了浮游动物的群落结构和地理分布特征,探讨了浮游动物群落与环境因子的关系.结果表明,在调查区域存在三种不同的浮游动物群落类型:楚科奇海台和加拿大海盆地区的高纬度深海群落;楚科奇海中部的陆架群落;阿拉斯加沿岸和楚科奇海北部的沿岸过渡群落.深海群落浮游动物数量较少,...     

Effects of environmental and biological conditions on the recruitment and growth of the Manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> on the west coast of Korea

The distribution of the Manila clam Ruditapes philippinarum, which is often dominant in intertidal zones, is influenced by both environmental and biological conditions. However, there have been few comprehensive studies on the interactive effects of these two groups of factors. The present study examined the environmental and biological parameters determining the population dynamics of the clams that is a dominant component of the intertidal communities of Euhangri and Padori on the west coast of Korean peninsula. We collected R. philippinarum and other members of the macrobenthos (> 1 mm long) monthly from 0.25 m² quadrats deployed in the intertidal zones at Euhangri, Taean, and Padori during the period from August 2013 to January 2015. Physicochemical parameters of the water and sediment were measured at the same time. Water temperature and salinity is high and low in the summer to winter, respectively. While mean grain size of the sediment was higher at Euhangri than at Padori, total mean density of R. philippinarum was higher at Euhangri (325 ind./ 0.25 m² at Padori vs. 194 ind./0.25 m² at Euhangri). Settled spat (< 10 mm in length) density was much higher at Euhangri than at Padori (132 vs. 12 individuals/0.25m², respectively). R. philippinarum spats settled down on the sediment at Euhangri in October and grew continually until the following May, when they reached adult size. Spats that settled down at Padori between March and April were not able to reach the adult stage. As the density of the adult population increased, the condition index of individual clams decreased, but as the population density of the spat increased the body condition index increased. The chlorophyll a content of the sediments at Padori exceeded that at Euhangri and decreased as the population of R. philippinarum increased. The shapes of R. philippinarum shells at Euhangri were more prolate than those at Padori, and the condition index at Euhangri exceeded that at Padori, indicating better growth conditions at Euhangri. The condition index and density of R. philippinarum were affected by the amount of chlorophyll a in the water column and in the sediment. The recruitment success of spats was negatively influenced by spat density. We suggest that regulation of habitat conditions for R. philippinarum, including the food supply, will optimize production of these commercial clams.     

Ventilation time and anthropogenic CO<Subscript>2</Subscript> in the Bering Sea and the Arctic Ocean based on carbon tetrachloride measurements

The Arctic Ocean is connected to the Pacific by the Bering Sea and the Bering Strait. During the 4th Chinese National Arctic Research Expedition, measurements of carbon tetrachloride (CCl₄) were used to estimate ventilation time-scales and anthropogenic CO₂ (C_ant) concentrations in the Arctic Ocean and Bering Sea based on the transit time distribution method. The profile distribution showed that there was a high-CCl₄ tongue entering through the Canada Basin in the intermediate layer (27.6?<?σ_θ?<?28), at latitudes between 78 and 85°N, which may be related to the inflow of Atlantic water. Between stations B09 and B10, upwelling appeared to occur near the continental slope in the Bering Sea. The ventilation time scales (mean ages) for deep and bottom water in the Arctic Ocean (~?230–380 years) were shorter than in the Bering Sea (~?430–970 years). Higher mean ages show that ventilation processes are weaker in the intermediate water of the Bering Sea than in the Arctic Ocean. The mean C_ant column inventory in the upper 4000 m was higher (60–82 mol m^?2) in the Arctic Ocean compared to the Bering Sea (35–48 mol m^?2).     

Characterization of Deep-sea Macrofauna in the Korean Exploration Claim Area in the Clarion-Clipperton Fracture Zone,Northeastern Pacific Ocean

Macrofauna in the Clarion-Clipperton Fracture Zone remain poorly understood, due both to gross undersampling and to the fact that most species collected from the area are new to science. Evaluation of the diversity and species distribution of the benthic fauna in this area is critical to predicting and managing the impacts of manganese nodule mining. In this study, we investigated the distribution of macrofauna to understand the natural variability in the macrobenthic community and, by extension, to establish a baseline for environmental risk assessment. Samples were collected from the KR5 block of the Korea Contract Area, within the abyssal area of the Clarion-Clipperton Fracture Zone in the northeastern Pacific Ocean, by the RV Onnuri from 2012–2014. A total of 36 core samples were examined in the survey, from which we identified 183 macrobenthic species in 25 faunal groups with a mean density of 257 ind/m2. Not taking into account meio-faunal groups such as nematodes and harpacticoid copepods, the highest percentage of individuals was represented by Arthropoda. The dominant species (> 1% of total density) were the tanaids Typhlotanais sp.1, and Akanthophoreus spp. and Stenotanais sp., the isopod Macrostylis sp.1, and the polychaetes Cirratulidae spp. and Levinsenia uncinata. The abundances of the two dominant species, the tanaid Typhlotanais sp1. and isopod Macrostylis sp.1., were positively correlated with total organic carbon (TOC). There were no differences in macrofaunal density and community structure between preserved areas (PRA), the potential benthic impacted site (BIS), and other areas near the BIS. In general, higher diversity was associated with homogeneous environmental conditions, with high nodule coverage (> 50%) and TOC.