UV-B辐射增强对壶状臂尾轮虫摄食的影响

研究了UV-B辐射条件下壶状臂尾轮虫(Brachionusurceus)对6株海洋微藻:小球藻(Chlorellasp.)、绿色巴夫藻(Pavlovauiridis)、扁藻(Tetraselmischuii)、球等鞭金藻8701(IsochrysisgalbanaPark8701)、牟氏角毛藻(Chaetocerosmuelleri)和小新月菱形藻(Nitzschiaclostertum)的室内摄食实验。结果表明,UV-B辐射增强对壶状臂尾轮虫的摄食有显著的抑制作用。与对照组相比,壶状臂尾轮虫对给定饵料单胞藻的滤水率和摄食率都随UV-B辐射剂量的增大而显著减小(P<0.05)。而且壶状臂尾轮虫对每一种饵料单胞藻的滤水率和摄食率是不相同的,这说明壶状臂尾轮虫对饵料单胞藻是有选择性的。     

Effects of UV-B radiation and different light repair conditions on the early development of the tetraspores of Chondrus ocellatus Holm

The effects of exposure to UV-B radiation,280-315 nm,and dark or dark repair conditions on the early development of Chondrus ocellatus Holm collected from Qingdao coast were studied under the laboratory condition.After being exposed to different doses [0,36,72,108,144 and 180 J/(m 2 · d)] of UV-B radiation,one treatment of tetraspores were put back to normal culture condition (PAR),the other treatment were put into dark condition to repair for 2 h.During the cultivation,the diameter of the tetraspores were recorded every 4 d till the 50th day when vertical branches formed in all treatments.Then at the 50th day,CPDs,phycoerythrin,chlorophyll a and MAAs (Palythine and asterina-330) were measured.The results showed that low doses UV-B radiation could significantly accelerate the growth rate of the tetraspores of C.ocellatus and the growth rate reduced gradually with UV-B radiation keep on increasing.The variation trend of both the phycoerythrin and chlorophyll a concentration reduced significantly ( P < 0.05) once given the UV-B radiation. Under UV-B stress,the CPDs were induced,and the concentrations of CPDs were significant low in dark repair groups.The data of MAAs analyzed by LC/MS in the tetraspores of C. ocellatus suggested that there were two MAAs formed (palythine and asterina-330) after UV-B radiation induced, and low dose of UV-B irradiation could significantly induced the concentration of MAAs.From the growth and development state of the tetraspores,negative effects of UV-B radiation on the dark repair groups were more serious than PAR.     

Impacts of solar UV radiation on grazing, lipids oxidation and survival of Acartia pacifica Steuer (Copepod)

UV radiation is known to affect aquatic primary producers and their grazers. However, little has been documented on its effects on zooplankton grazing. In this study, the authors investigated the effects of photosynthetically active radiation (PAR, 400-700 nm), ultraviolet-A (UV-A, 320-400 nm) and ultraviolet-B (UV-B, 280-320 nm) radiation on grazing, mortality and lipids oxidation of the copepod Acartia pacifica collected from the Xiamen Bay. After 30 min of the exposures, the copepod was fed in darkness with the diatom Phaeodactylum tricornutum at two cell concentrations (2.5 × 10 4 and 2.5 × 10 5 cells/ml). At the low cell concentration, the individuals pre-exposed to PAR (218.0 W/m 2 )+UV-A (48.2 W/m 2 ) or PAR+UV-A+UV-B (2.1 W/m 2 ) showed suppressed clearance and grazing activities compared with those receiving PAR alone, by 22.7% and 17.1% for clearance and by 22.6% and 5.5% for grazing rates, respectively. However, the suppression on clearance and grazing became indistinctive at the high food concentration. Exposures to UV-A and UV-B led to increased lipid oxidation and higher mortality, furthermore, the mortality linearly increased with enhanced oxidation of lipid.     

Effect of UV-B radiation on the feeding behavior of the rotifer Brachionus plicatilis

Effect of UV-B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV-B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV-B radiation on five species of microalgae, i.e., Chlorella sp., Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV-B radiation when fed with five species of microalgae respectively (P<0.05) which indicates UV-B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp., then C. muelleri,I. galbana, N. clostertum and T. chuii in turn if without UV-B radiation. Under the highest dose of UV-B radiation treatment (2.70 kJ/m2), the rotifer preferred to feed C. muelleri, then Chlorella sp., N. clostertum, I. galbana and T. chuii in turn. Chlorella sp., I. galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV-B radiation will lead to the change in the structure of phytoplankton community.     

南极绿藻中类菌胞素氨基酸对UV-B胁迫的响应

南极上空臭氧层的破坏导致了紫外辐射日益增强,高强度的UV-B辐射会造成细胞中DNA的损伤,影响蛋白质、脂类和色素的代谢过程。生长在南极的绿藻具有一系列防御机制以应对增强的UV-B辐射,其中类菌胞素氨基酸(Mycosporine-like amino acids, MAAs)是一类重要的紫外防御物质。为探究类菌胞素氨基酸对UV-B辐射的响应,本文以南极冰藻(Chlamydomonassp.ICE-L)、针丝藻(Raphidonema nivale Lagerheim, NIES-2290)和胶球藻(Coccomyxa subellipsoidea E.Acton, NIES-2166)三种生活在南极的绿藻为材料,采用UV-B辐射胁迫(强度0.35 W/m~2,短时处理3 h),并通过液相色谱-质谱联用法检测类菌胞素氨基酸的种类和含量的变化。Mycosporine-glycine为三种南极绿藻中共有的MAAs,在UV-B辐射胁迫下三种南极绿藻中Mycosporine-glycine含量变化不尽相同,表明不同的南极绿藻中MAAs对UV-B辐射的响应各有其特性。首次在绿藻(南极冰藻和胶球藻)中检测到Gadusol。Gadusol作为MAAs的合成前体,它的合成积累使得生活在海冰环境的南极冰藻和胶球藻具有良好的抗UV-B辐射能力。其中南极冰藻抗紫外能力最强,这可能得益于不同MAAs间的动态转化,含量升高的Palythine及Usujirene/Palythene可能对南极冰藻的紫外屏蔽起着至关重要的作用。     

海洋卡盾藻对青岛大扁藻的化感作用及其对UV-B辐射的响应

本研究以海洋微藻——赤潮藻海洋卡盾藻(Chattonella marina)与饵料藻青岛大扁藻(Platymonas helgolandica var.tsingtaoensis)为研究对象,采用单培养和共培养的方法,研究二者间的竞争关系,并在此基础上研究海洋卡盾藻去藻过滤液和藻细胞裂解液对青岛大扁藻的化感作用,同时进一步探讨两种海洋微藻间的化感作用对UV-B辐射增强的响应。结果显示:共培养条件下,海洋卡盾藻在2个高浓度下对青岛大扁藻的生长产生显著抑制(P0.05);海洋卡盾藻去藻过滤液和藻细胞裂解液对青岛大扁藻的生长也具有显著抑制作用(P0.05),且藻细胞裂解液的抑制作用更强,说明海洋卡盾藻对青岛大扁藻产生化感作用,且通过细胞间直接接触传递的化感物质多于通过介质传递的。不同密度比例的2种藻共培养组用UV-B辐射(2.16J/m2)处理后,海洋卡盾藻对青岛大扁藻生长的化感作用有所减弱。     

Comparison of the biology, dynamics, and secondary production of Talorchestia brito (Amphipoda, Talitridae) in Atlantic (Portugal) and Mediterranean (Tunisia) populations

The biology, population dynamics, and production of Talorchestia brito were studied at two sandy beaches located on the Atlantic (Portugal) and on the Mediterranean (Tunisia) coasts, respectively. The seasonal variation in abundance and the overall densities were similar in both populations. Reproduction occurred from February to September in the Atlantic, and from March to early November in the Mediterranean. The sex ratio was male biased in the Atlantic, and female biased in the Mediterranean. Based on data from the Atlantic population, both abundance and the proportion of reproductive females were positively correlated with temperature, while the proportion of juveniles in the population was positively correlated with temperature and sediment moisture. On average, individuals from the Atlantic were larger than the ones from the Mediterranean. Life span was estimated at six to nine months in the Atlantic, and five to eight months in the Mediterranean. Talorchestia brito was shown to be a semiannual species, with iteroparous females producing two broods per year, and exhibited a bivoltine life cycle. The minimum age required for males' and females' sexual differentiation and for female sexual maturation was shorter in the Mediterranean. Growth production (P) was estimated at 0.19 g m⁻² y⁻¹ ash free dry weight (AFDW; 4.3 kJ m⁻² y⁻¹) in the Atlantic population, and 0.217 g m⁻² y⁻¹ AFDW (4.9 kJ m⁻² y⁻¹) in the Mediterranean one. Elimination production (E) was estimated at 0.35 g m⁻² y⁻¹ AFDW (7.9 kJ m⁻² y⁻¹) in the Atlantic, and 0.28 g m⁻² y⁻¹ AFDW (6.3 kJ m⁻² y⁻¹) in the Mediterranean. The average annual biomass ( ) (standing stock) was estimated at 0.032 g m⁻² in the Atlantic beach, and 0.029 g m⁻² in the Mediterranean one, resulting, respectively, in ratios of 5.9 and 7.5 and ratios of 10.8 and 9.6. Like other talitrids, T. brito exhibited geographic variation in morphometrical characteristics, sex ratio, growth rates, life span, and reproduction period, with the Atlantic population presenting a slower life history.     

Differential UVB‐sensitivities of five New Zealand freshwater zooplankton species

Abstract

The ultraviolet (UV) sensitivity of five species of freshwater zooplankton (three Cladocera, two Copepoda) were investigated. The animals were exposed to varying levels of UV‐radiation in a sunshine‐simulator and the UV doses for 10 and 50% mortality (LD₁₀, LD₅₀) were estimated using a dose‐response model. To place these doses in context they were compared with modelled clear‐sky surface UV irradiances in New Zealand. The cladocerans Daphnia carinata and Ceriodaphnia dubia were sensitive to levels of UVB irradiance of LD₁₀ = 18–25 kJ m^?2 and LD₅₀ = 35–37 kJ m^?2. These sensitivities are consistent with published values for other cladocera. In contrast a third cladoceran, Bosmina meridionalis, exhibited no higher mortality over the full range of the cumulative UVB‐doses used (3–40 kJ m^?2) than controls receiving no UV exposure. The copepod Boeckella delicata showed the highest UV‐sensitivity of all organisms tested (LD10 = 7 kJ m^?2, LD50 = 33 kJ m^?2) whereas for Boeckella triarticulata, which was more heavily pigmented than B. delicata, no UV‐induced mortality was observed. Under natural conditions UV irradiances of up to 100 kJ m^?2 day^?1 can fall on the surface of New Zealand lakes. Although this is attenuated in natural waters, these data suggest that UVB irradiance may be a significant ecological variable to some zooplankton species.     

Implications of mycosporine-like amino acid and antioxidant defenses in UV-B radiation tolerance for the algae species Ptercladiella capillacea and Gelidium amansii

Ultraviolet-B (UV-B) radiation (0.5, 1.0, 1.5, and 3.0 W m^?2) induced higher H₂O₂ production and lipid peroxidation in alga Gelidium amansii inhabiting in lower subtidal regions than upper subtidal alga Ptercladiella capillacea. Compared to G. amansii, mycosporine-like amino acid (MAA) concentration in P. capillacea was higher and can be increased by 0.5–1.0 W m^?2 UV-B, while carotenoid concentration was lower but also increased by 1.5–3.0 W m^?2 UV-B. UV-B increased ascorbate concentration, but to a higher degree in P. capillacea. UV-B decreased glutathione concentration, but to a higher degree in G. amansii. UV-B increased ascorbate peroxidase (APX) and glutathione reductase (GR) activities in P. capillacea but decreased them in G. amansii. UV-B increased superoxide dismutase and catalase activities, but to a higher degree in G. amansii. So, G. amansii suffered greater oxidative stress from UV-B radiation. P. capillacea can effectively reduce UV-B sensitivity by increasing sunscreen ability and antioxidant defense capacity.     

急性UVB辐射对粉叶马尾藻过氧化损伤和主要抗氧化酶的影响

粉叶马尾藻(Sargassum glaucescens)是台湾地区潮间带的重要大型藻类,其对紫外线增强的生理响应特征尚不清楚。本研究关注粉叶马尾藻在急性紫外线辐射(Ultraviolet radiation B,UVB)下的生理指标变化,探索了粉叶马尾藻在急性UVB辐照下抗氧化系统的瞬时反应过程。结果表明:低强度组[0.5W/(m2·s)]藻体在24h内未出现显著氧化损伤和蛋白质含量变化,但是细胞活力在辐照12h后显著降低,藻体超氧化物歧化酶(SOD)酶活性随辐照时间延长而降低,过氧化氢酶(CAT)酶活性呈现升高后下降的趋势,抗坏血酸过氧化物酶(APX)酶活性没有出现显著降低;高强度组[2W/(m2·s)]藻体在辐照3h后藻体出现明显氧化损伤,6h后细胞活力和蛋白质含量显著降低,藻体SOD酶活性随辐照时间延长而降低,CAT和APX酶活性呈现升高后降低的趋势,辐射12h后即显著降低。低强度UVB辐射对粉叶马尾藻的影响相对较小,表明粉叶马尾藻对UVB辐射具有一定耐受性;而高强度UVB辐射的影响较为显著,意味着UVB辐射的持续增强将超出粉叶马尾藻的耐受限度,进而造成不利影响。本研究结果初步揭示了粉叶马尾藻对于急性UVB辐射的增强的生理响应特征,为进一步研究UVB辐射增强的生态学效应提供参考依据。     

紫外光对有毒甲藻塔玛亚历山大藻的生态学效应

对1991年分离自南海大鹏湾海域的塔玛亚历山大藻单克隆培养林在不同光照条件、辐射强度（9.5，5．9W／m2）（辐射剂量为：95，190，380,760,1520J/m2）和营养盐（N，P）浓度下，进行紫外辐射敏感性的研究。结果表明，紫外辐射可以导致细胞变形、增大和死亡。不论在什么条件下，低剂量的紫外辐射（95J／m2）就能使该藻的存活率和生长率大幅下降。此后，随着辐射剂量的增加，虽然存活率和生长率继续下降，但下降幅度渐缓。充足的营养盐和辐射处理后的连续光照对藻群的恢复有益，但在缺氮和缺磷条件下培养的藻群，可能由于生理活性减弱而导致对紫外辐射敏感性的迟钝。辐射强度对该藻的紫外辐射敏感性的影响十分显著，而且与辐射剂量具有明显的双重效应。     

Growth, Production, and a Partial Energy Budget for the Amphipod, Talorchestia capensis (Crustacea; Talitridae) in the Eastern Cape, South Africa

Abstract. .A population of Talorchestia capensis was sampled in dune slacks over the period of one year. Two hatching periods, one in March and one in September, were observed. Growth was rapid, the amphipods reaching a size of 8.4 mm standard length in 18 months. Maximum growth occurred in spring and minimum growth in winter. Annual mortality rates for summer- and winter-hatched individuals were low, 0.22-y“¹ and 0.16-y”¹. Average production for the summer classes was 7.2g-y?‘ (dry mass) and for the winter classes 2.9-y“¹, with a P/B ratio of 2.25-y”’. Production values peaked during autumn and summer. Abundance and biomass estimates showed maxima during summer and minima in early spring. Reproductive output was low, 0.1 kJ ? m^-2 y“¹, indicating that 7 % of the total production is used for reproduction and 93 % for somatic production. The assimilated energy flow through the population was estimated to be 16.3 kJ m?² y?‘ and consumption about 81.6 kJ m^-2 y^_’.     

Seasonal dynamics of Zostera noltii hornem. In the bay of arcachon (France)

Seasonal dynamics of Zostera noltii was studied during 1984 in Arcachon Bay, France. In this Bay, Z. noltii colonizes 70 km², i.e. approximately 50% of the total area, while Z. marina occupies only 4 km². Densities and length of vegetative and generative shoots and above-ground and below-ground biomasses were monitored in four meadows which differed according to their location in the Bay, tidal level and sediment composition. Three of these meadows were homogeneous, well-established beds whilst the fourth was under colonization and patchy. Shoot densities and maximal below-ground biomass were lower in the inner silty seagrass bed than in the sandy meadows located in the centre of the Bay. Maximal above-ground biomasses were similar in the two population types. In the well-established beds, vegetative shoot densities, above-ground and below-ground biomasses showed a unimodal pattern with minima in winter (4000 to 9000 shoots·m⁻², 40 to 80 g DW·m⁻², and 40 to 60 g DW·m⁻², respectively) and maxima in summer (11000 to 22000 shoots·m⁻², 110 to 150 g DW·m⁻², and 140 to 200 g DW·m⁻², respectively). Reproductive shoots were observed from the beginning of June until the end of September, except in the colonizing bed where they persisted until December. Furthermore, in the latter, maximal reproductive shoot density was higher (2600 shoots·m⁻²) than in the established beds (650 to 960 shoots·m⁻²). The total production of Z. noltii in Arcachon Bay was estimated to approximately 35.6·10⁶ kg DW·y⁻¹ (19.4·10⁶ kg DW·y⁻¹ for above-ground parts and 16.2·10⁶ kg DW·y⁻¹ for below-ground parts).     

2003-2016年北极净初级生产力时空变化

The area of Arctic sea ice has dramatically decreased, and the length of the open water season has increased;these patterns have been observed by satellite remote sensing since the 1970 s. In this paper, we calculate the net primary productivity(NPP, calculated by carbon) from 2003 to 2016 based on sea ice concentration products,chlorophyll a(Chl a) concentration, photosynthetically active radiation(PAR), sea surface temperature(SST), and sunshine duration data. We then analyse the spatiotemporal changes in the Chl a concentration and NPP and further investigate the relations among NPP, the open water area, and the length of the open water season. The results indicate that(1) the Chl a concentration increased by 0.025 mg/m~3 per year;(2) the NPP increased by 4.29 mg/(m~2·d) per year, reaching a maximum of 525.74 mg/(m~2·d) in 2016; and(3) the Arctic open water area increased by 57.23×10~3 km~2/a, with a growth rate of 1.53 d/a for the length of the open water season. The annual NPP was significantly positively related to the open water area, the length of the open water season and the SST.The daily NPP was also found to have a lag correlation with the open water area, with a lag time of two months.With global warming, NPP has maintained an increasing trend, with the most significant increase occurring in the Kara Sea. In summary, this study provides a macroscopic understanding of the distribution of phytoplankton in the Arctic, which is valuable information for the evaluation and management of marine ecological environments.     

养殖密度对循环水系统中大菱鲆生长和蛋白质代谢的影响

在工厂化循环水养殖系统中,将初始体质量为186 g±2.0 g的大菱鲆(Scophthalmus maximus)放养于低(9.4 kg/m~2±0.2 kg/m~2)、中(13.6 kg/m~2±0.8 kg/m~2)、高(19.1 kg/m~2±1.3 kg/m~2)3个养殖密度,以研究不同养殖密度对大菱鲆生长、消化酶和蛋白质代谢的影响。养殖120 d后,低、中、高试验组养殖密度分别增长至26.1 kg/m~2±1.2 kg/m~2、38.2 kg/m~2±2.5 kg/m~2、52.3 kg/m~2±3.6 kg/m~2。结果表明:低密度组和中密度组中大菱鲆增质量率、特定生长率、肥满度和蛋白质效率均显著(P0.05)高于高密度组;而饲料系数显著低于高密度组(P0.05)。低密度组和中密度组大菱鲆总蛋白酶和淀粉酶活力显著低于高密度组(P0.05);但脂肪酶活力在3个密度组之间无显著性差异。与低密度组相比,高密度组显著提高了谷氨酸脱氢酶活力,同时降低了谷草转氨酶和亮氨酸氨肽酶活力(P0.05),而对谷丙转氨酶活力无任何影响。综上所述,在工厂化循环水系统中,增加养殖密度能提高养殖的产量,但过高的养殖密度会对大菱鲆生长、消化酶活力以及蛋白质代谢产生不利的影响。     

河北沿岸微微型浮游植物的分布特征

于2006年7月～ 2007年10月间,分4个季度调查了河北省沿岸微微型浮游植物的丰度和生物量及对浮游植物总生物量的贡献.结果显示:河北近岸海域聚球藻蓝细菌丰度为4.46×103个/mL(0.79×103～ 16.19×103个/mL),生物量(以碳计,下同)为1.31 mg/m3 (0.84～17.47 mg/m3),季节分布特征为秋季＞冬季＞夏季＞春季.微微型光合真核生物丰度为4.43×102个/mL (0.84×102～ 17.47×102个/mL),生物量为1.11mg /m3 (0.21～ 4.37 mg/m3),季节变化变现为秋季＞冬季＞春季＞夏季.微微型浮游植物对浮游植物总生物量的贡献年平均为5.32％(1.84％～ 8.91％),春季最高,秋季最低.温度在较冷季节(冬春季)里是影响聚球藻蓝细菌生长和分布的控制因素.总之,在近岸环境里,微微型浮游植物并不占优势.     

基于多元统计分析的渔山列岛潮间带软体动物功能群和次级生产力比较

渔山列岛于2008年成为国家级海洋生态保护区,为了解渔山列岛保护区内潮间带软体动物次级生产力的时空变化。于1982年和2010年的3个季节(春、夏、冬)在渔山列岛进行潮间带软体动物调查,采用多元统计分析软体动物时空差异,以Brey经验公式计算分析软体动物次级生产力(P值,P/B值)。结果表明,年际间物种食性结构发生了明显的改变,1982年潮间带软体动物对次级生产力贡献率最大的物种有单齿螺(Monodonta labio)、锈凹螺(Chlorostoma rustica),占软体动物总次级生产力的42.88%,2010年潮间带软体动物对次级生产力贡献率最大的物种有覆瓦小蛇螺(Serpulorbis imbricata)、条纹隔贻贝(Septifer virgatus),占软体动物总次级生产力的75.96%。1982年,年均栖息密度为2758ind/m2,年均生物量为2100.26g/m2,年均次级生产力为240.04g/(m2·a),年均P/B值为0.63a–1;2010年,年均栖息密度为699ind/m2,年均生物量为1101.85g/m2,年均次级生产力为94.82g/(m2·a),年均P/B值为0.55a–1。多因素方差分析表明软体动物次级生产力年际间差异显著(F=5.761,P0.05),季节间和潮位间差异都不显著(F=0.135,P0.05;F=2.076,P0.05),P/B的值较低,表明该海域软体动物世代更替速度较慢,2010年的P/B值(0.55a–1)低于1982年的P/B值(0.63a–1),表明近30年来群落结构受到影响。     

Seasonal variability of leaf litter removal by crabs in a Kandelia candel mangrove forest in Jiulongjiang Estuary, China

The seasonal variability of leaf litter removal by crabs was observed from May 2006 to April 2007 in a Kandelia candel mangrove forest in Jiulongjiang Estuary, China. Daily average quantities of leaf fall ranged 0.85–3.86 gDW m⁻² d⁻¹, with high values in May, August, October and November. The whole-year's leaf fall was 6.48 t ha⁻¹ yr⁻¹ (1.81 gDW m⁻² d⁻¹). The standing stock of leaf litter on the forest floor was 7.78 gDW m⁻² averaged from the whole year's data, with the lowest value in December (1.23 gDW m⁻²) and the highest in April (16.18 gDW m⁻²). Annually averaged removal (consumption on mangrove floor + burial in burrows) rate of leaf litter by crabs was 0.59 gDW m⁻² d⁻¹. High seasonal variability was observed in the removal rates of leaf litter by crabs. Removal rates in the winter months (December, January and February) were 0.07–0.09 gDW m⁻² d⁻¹, much lower than those in other months with values of 0.59–1.18 gDW m⁻² d⁻¹. Annually averaged percentage of leaf fall removed by crabs was 33%, with the highest values in September (reached 76%) and the lowest values in winter months. Of leaf litter removed by crabs, a large proportion was buried by crabs, and only 12% was consumed by crabs on the forest floor. Leaf litter removal rate, consumption rate on the forest floor, percentages of leaf fall and standing stock removed on the forest floor were significantly positively correlated with air temperature, indicating that leaf removal ability by crabs was higher in warm months than in cold months.     

A potential source of recruitment of Acartia pacifica nauplii: viable benthic resting eggs

Many estuarine and coastal planktonic copepods depend on the hatching of benthic resting eggs for recruitment of nauplii to the water column population. The distribution and abundance of viable resting eggs of Acartia pacifica in the Xiamen Bay were determined by the presence of nauplii in the laboratory. The number of viable eggs varied temporally and spatially. The maximum number (9.2×10⁴m^-2) of viable eggs was in summer. In spring the average abundance of viable eggs was 5.6×10⁴ m^-2. The abundances of viable eggs in fall and winter were similar, respectively 2.7×10⁴ and 3.3×10⁴ m^-2, which were the lowest in the year. The numbers of viable eggs inside the stations of the Xiamen Bay were higher than those outside the stations. The viable eggs were found at all depths (0～10 cm),although not in every station. The maximin number did not necessarily occur in the uppermost centimeter of the sediments but often occurred several centimeters below the water-sediment interface. The accumulation of viable eggs in the seabed of a subtropical bay constitutes a potential source of recruitment of nauplii into the pelagic population.     

fCO2 variability at the CARIACO tropical coastal upwelling time series station

Monthly seawater pH and alkalinity measurements were collected between January 1996 and December 2000 at 10°30′N, 64°40′W as part of the CARIACO (CArbon Retention In A Colored Ocean) oceanographic time series. One key objective of CARIACO is to study temporal variability in Total CO₂ (TCO₂) concentrations and CO₂ fugacity (fCO₂) at this tropical coastal wind-driven upwelling site. Between 1996 and 2000, the difference between atmospheric and surface ocean CO₂ concentrations ranged from about − 64.3 to + 62.3 μatm. Physical and biochemical factors, specifically upwelling, temperature, primary production, and TCO₂ concentrations interacted to control temporal variations in fCO₂. Air–sea CO₂ fluxes were typically depressed (0 to + 10 mmol C m^{− 2} day^{− 1}) in the first few months of the year during upwelling. Fluxes were higher during June–November (+ 10 to 20 mmol C m^{− 2} day^{− 1}). Fluxes were generally independent of the slight changes in salinity normally seen at the station, but low positive flux values were seen in the second half of 1999 during a period of anomalously heavy rains and land-derived runoff. During the 5 years of monthly data examined, only two episodes of negative air–sea CO₂ flux were observed. These occurred during short but intense upwelling events in March 1997 (−10 mmol C m^{− 2} day^{− 1}) and March 1998 (− 50 mmol C m^{− 2} day^{− 1}). Therefore, the Cariaco Basin generally acted as a source of CO₂ to the atmosphere in spite of primary productivity in excess of between 300 and 600 g C m^{− 2} year^{− 1}.