Ferromanganese nodule fauna in the Tropical North Pacific Ocean: Species richness,faunal cover and spatial distribution

The poorly known ferromanganese nodule fauna is a widespread hard substratum community in the deep sea that will be considerably impacted by large-scale nodule mining operations. The objective of this study was to analyze the spatial distribution of the fauna attached to nodules in the Clarion-Clipperton Fracture Zone at two scales; a regional scale that includes the east (14°N, 130°W) and the west (9°N, 150°W) zones and a local scale in which different geological facies (A, B, C and west) are recognizable. The fauna associated with 235 nodules was quantitatively described: 104 nodules from the east zone (15 of facies A, 50 of facies B and 39 of facies C) and 131 nodules from the west zone. Percent cover was used to quantify the extent of colonization at the time of sampling, for 42 species out of the 62 live species observed. Fauna covered up to 18% of exposed nodule surface with an average of about 3%. While species richness increased with exposed nodule surface, both at the regional and at the facies scales (except for facies A), total species density decreased (again except for facies A). When all nodules were included in the statistical analysis, there was no relation between faunal cover and exposed nodule surface. Nevertheless, faunal cover did decrease with exposed nodule surface for the east zone in general and for both facies B and C in particular. Species distributions among facies were significantly different but explained only a very small portion of the variance (∼5%). We identified two groups of associated species: a first group of two species and a second group of six species. The other species (34) were independently distributed, suggesting that species interactions play only a minor role in the spatial distribution of nodule fauna. The flux of particulate organic carbon to the bottom is the only major environmental factor considered to vary between the two zones within this study. We conclude that the higher species richness and higher percent faunal cover of the east zone can be partially attributed to greater food availability derived from surface inputs. Moreover, the surfaces of facies B and C nodules had a complex, knobby micro-relief, creating microhabitat heterogeneity that may also have contributed to the greater species richness observed in the east zone.     

Latitudinal change in benthic foraminiferal fauna by ITCZ movement along the ~131°W transect in the equatorial Pacific Ocean

Modern and fossil benthic foraminifera were examined from nine surface sediments and two piston cores along the ~131°W transect in the equatorial Pacific Ocean. This study was conducted to clarify the biotic response of abyssal benthic foraminifera during the last 220 ka to changes in the seasonal extent of the Intertropical Convergence Zone (ITCZ). The abundance of modern benthic foraminifera was high at stations between the equator and 6°N, whereas it was low at stations north of 6°N, which is generally consistent with the latitudinal CaCO₃ distribution of surface sediments. The northward increase of Epistominella exigua from the equator to ~6°N is similar to the seasonal variations in chlorophyll-a concentrations in the surface water and ITCZ position along ~131°W. This species was more common at core PC5103 (~6°N) than at core PC5101 (~2°N) after ~130 ka, when the Shannon-Wiener diversity (H’) between the two cores started to diverge. Hence, the presentday latitudinal difference in benthic foraminifera (E. exigua and species diversity) between ~2°N and ~6°N along ~131°W has been generally established since ~130 ka. According to the modern relationship between the seasonality of primary production and seasonal ITCZ variations in the northern margin of the ITCZ, the latitudinal divergence of benthic foraminiferal fauna between ~2°N and ~6°N since ~130 ka appear to have been induced by more distinct variations in the seasonal movement of ITCZ.     

Changes in the faunal composition of two thermal streams near Taupo,New Zealand

The distributions of macroinverte‐brates in two thermal streams near Taupo were examined and compared with observations made in 1966. The cooling of the streams associated with abstraction has altered the species composition. Odonata and Trichoptera were recorded for the first time in the lower reaches of the Waipahihi Stream whereas Ephydridae and Hydrophilidae were restricted to the upper reaches at temperatures above 33.5°C. Molluscs dominated the fauna at sites with temperatures below 33.5°C in the Waipahihi and Waipuwerawera Streams. Potamopyrgus anti‐podarum was present at sites with temperatures below 28°C.     

The effects of beach replenishment on the benthos of a sub-tropical Florida beach

Changes in the benthic fauna of the near-shore zone were examined before and after a beach replenishment project on the central Florida east coast. Results indicated that the near-shore sand beach community is relatively species rich, although abundance is dominated by only two species of bivalves, the coquina clams Donax variabilis and Donax parvula. Strong gradients of increased species richness and abundance were found, with values increasing at the more seaward sites for both control and nourishment locations. This distributional pattern was unchanged by beach nourishment. Comparison of mean number of individuals per core across dates and among transects (two-way analysis of variance) showed no indication of significant negative effects of beach nourishment. Similar analysis for mean number of species per core also failed to show significant negative effects. Negative biological effects of beach nourishment may have been minimized in the present case due to a seasonal offshore movement of the dominant coquina clams. The close match of mean fill grain size to ambient grain size and an apparent lack of substantial fill movement into the biologically more diverse offshore areas may also have diminished biological damage.     

Community structure in mussel beds at Logatchev hydrothermal vents and a comparison of macrofaunal species richness on slow- and fast-spreading mid-ocean ridges

Species lists for vent fields on the Mid‐Atlantic Ridge (MAR) from 14°N to 38°N suggest that there is a northern (>27°N), shallow (<2000 m) fauna and a southern (<27°N), deeper (>3000 m) endemic vent fauna, but little is known about how community structure varies along the ridge axis. In this study, quantitative samples of macrofaunal invertebrates associated with mussels (Bathymodiolus puteoserpentis) were collected at Logatchev (14°45′N), the southern‐most explored vent field on the MAR. Community structure (including species composition, species richness, diversity, and relative species abundances) in mussel beds at Logatchev was compared with that of Snake Pit (23°22′N) and Lucky Strike (37°17′N) mussel beds. The most striking feature of the Logatchev mussel‐bed macrofaunal invertebrate community was the tremendous abundance (up to 2390 individuals per liter of mussel‐volume sampled) and biomass of the ophiuroid, Ophioctenella acies. Logatchev and Snake Pit mussel beds share >50% of their associated macrofaunal species; these two sites share only 20–25% of their macrofaunal species with Lucky Strike. Species–effort curves and univariate measures of diversity (H′, J′) do not support the claim that diversity of vent organisms on the MAR is highest at Logatchev, at least when one assesses this within a habitat type. Multivariate analysis readily differentiates the species‐abundance characteristics of Logatchev, Snake Pit, and Lucky Strike mussel‐bed macrofaunas. The relationship between sea‐floor spreading rate and diversity was explored through comparison of species richness in mussel‐bed habitats on slow‐spreading (MAR), fast‐spreading [northern East Pacific Rise (EPR)], and ultra‐fast‐spreading (southern EPR) mid‐ocean ridges. Species richness was greater in samples from the faster‐spreading ridge axes, where vents are more closely spaced but shorter lived, than on slow‐spreading centers, where vents are further apart but longer lived.     

A pelagic ecosystem model calibrated with BATS and OWSI data

Ocean ecosystems play an important role in the global carbon cycle. In this paper, we develop and calibrate a pelagic ocean ecosystem model by simultaneously fitting data from two sites in the North Atlantic: the site of the Bermuda Atlantic Time-series Study (BATS, 32°N, 64°W) and Ocean Weather Ship Station “I” (OWSI, 59°N, 20°W). These sites differ dramatically in the magnitude and timing of primary production, chlorophyll concentrations, and light and nutrient availabilities. We find that a relatively simple model can be simultaneously fit to ecosystem data at both sites. As in the model of Hurtt and Armstrong (1996, Deep-Sea Research II 43(2–3): 653–683), the fit largely depends on the inclusion of multiple size classes of phytoplankton and detritus and a variable chlorophyll-to-biomass (nitrogen) ratio for phyto-plankton. The inclusion of these features in the model enables it to adjust to predict important biological differences temporally within sites and spatially between sites. In addition, the model also includes a phytoplankton self-shading parameter to capture differences in water clarity between sites, and the parameterization of iron limitation at OWSI as a hypothesis for the moderately HNLC condition there. Finally, we suggest that the model performs reasonably well at the Hawaii Ocean Time-series (HOT, 23°N, 158°W), a site where no model calibration was done.     

东海放射虫的研究 I. 等辐骨虫目

等辐骨虫目(Acantharia)是原生动物放射虫纲中的一大类, Müller(1858)最初称这类动物为Acanthometra,并发现其骨针排列的规律[后人称之为穆勒氏律(Müllers law)]。继后,Haeckel在1862-1887年先后发表了两部放射虫专著,其中共描述了等辐骨虫七百多种,又把这类动物改称为Acantharia,在分类系统上,奠定了初步基础。1904-1906 年,Popofsky根据1887年Hensen领导进行的浮游生物调查所获的放射虫资料,先后发表了两篇报告,共记述了等辐骨虫三百多种,其中增加了许多新的科属,对Haeckel的分类系统作了些修改,对种类亲缘关系的解释亦进了一步。1906-1907年,Mielck 利用在俾斯麦群岛中采到的等幅骨虫作研究,他提出的分类方怯,更注意到等辐骨虫虫体的柔软部分(例如中央囊等);虽然工作甚少,但颇有学术价值。 在分类研究史上,Schewiakoff是等辐骨虫分类系统的重大改革者,1926年,他发表了那波利湾(Bay of Naples)的等辐骨虫专著,由于用活体观察法和理化方法进行了研究,观察到许多前人所未见的形态和结构,例如发现等辐骨虫并非全部都有中央囊,有的只具内胶膜,并且查明了中央囊内也有外质的存在。此外,根据个体发育的观察研究,归并和订正了前人所鉴定的许多种属。Schewiakoff在分类上,不仅以骨骼结构、而且还以中央囊及胶膜的有无、肌原纤维的形状和数目等等作为依据,故他所提出的分类系统比较合理。 近年来,对等辐骨虫分类系统进行研究的有Trégouboff(1953)和Campbell(1954)等人,Trégouboff所讨论的系统基本上是依照Schewiakoff;Campbell虽然提出了新的分类系统,可惜没有提出更多的理由来说明。 有关等辐骨虫化石及其在地层学上的实际价值,迄今还报导得很少,Davis (1950)在奥曼(Oman)曾发现放射虫的Mayenella新属,他认为这是等辐骨虫的化石,并且提出可以利用它作为鉴别中生代地层的指示化石,但Campbell认为该属并非等辐骨虫而把它归并到泡沫虫目(Spumellaria)中去。早在1887年,Haeckel 就认为本类动物根本没有化石,因为它的骨骼是由硫酸锶或Acantin质组成,易被海水溶解,但Campbell & Clark(1944)在美国加利福尼亚南部中生代地层中还是发现了等辐骨虫(Acanthometron astraeforme)的化石。此外,在Campbell(1954)的放射虫分类系统中也列出等辐骨虫的某些科属有化石的种类,然而,终究因为本类动物的化石迄今发现尚少,故在地层学的价值上未见有显著的地位。 关于我国海区的等辐骨虫,以往报告的很少,仅1932年王家楫与倪达书曾记录过厦门的一种,即Acanthometra pellucida J. Müller。1958年以来,我们进行了东海的放射虫调查研究,本文即是研究报告的第一部分,着重在等辐骨虫分类学方面的研究,并讨论了它们在东海的数量分布。     

Biological features of Pupu Springs

The flora and fauna of Pupu Springs (40°51'S, 172° 46'E) and five other New Zealand cold springs are described. In Pupu Springs there are 16 species of algae, 10 species of bryophytes (including three species of liverworts), and 5 species of angiosperms. The fauna includes a phreatic form (an eyeless planarian, Dugesia sp.), a possible glacial relict (the caddis fly Rakiura vernale), and cold stenotherms (e.g., the caddis fly Psilochorema tautoru). The most abundant animals in the New Zealand springs are Mollusea, Crustacea, and’ larvae of Plecoptera, Diptera, and Trichoptera.

Pupu Springs consist of five biotopes and associated biocoenoses.     

Coral communities and reefs from Guerrero,Southern Mexican Pacific

Corals in the Eastern Pacific extend south from the Gulf of California to Ecuador and oceanic Chile, and west from Colombia to Clipperton Atoll. Nevertheless, large stretches of the Mexican Pacific remain fundamentally unstudied. Therefore, to assess the current conditions of coral communities, a coastal fringe ～300 km long (17°40′ N, 101°39′ W to 16°46′ N, 99°49′ W) was surveyed within the Southern Mexican Pacific, between 2005 and 2009. Fifteen stony coral species were identified at 13 coral communities and six Pocillopora‐dominated fringing reefs, with Pocillopora verrucosa and Pocillopora damicornis the primary contributing taxa. Reef development was identified in embayments or behind rocks or islands that offered shelter from northern and northwestern winds. Observations of Pocillopora effusus, Pocillopora inflata, Porites lobata, Pavona clavus, and Pavona varians expanded the species known geographic ranges by several degrees of latitude, suggesting reef building fauna comprised a mixture of widespread and relatively rare Eastern Pacific corals. Results indicated greater live coral cover in the Ixtapa‐Zihuatanejo area (15–73%) than in the Acapulco localities, which had high algal dominance; the reefs in the latter region exhibited high erosion. Regional differences are likely the result of long‐standing anthropogenic pressures around Acapulco since 1950, when it became an important tourist destination. This paper is the first detailed report of ecologically stressed corals and coral reefs from the state of Guerrero on the Mexican Southern Pacific coast.     

Diversity of faunal assemblages associated with ribbed mussel beds along the South American coast: relative roles of biogeography and bioengineering

Benthic organisms are among the most diverse and abundant in the marine realm, and some species are a key factor in studies related to bioengineering. However, their importance has not been well noted in biogeographic studies. Macrofaunal assemblages associated with subtidal beds of the ribbed mussel (Aulacomya atra) along South America were studied to assess the relationship between their diversity patterns and the proposed biogeographic provinces in the Southeastern Pacific and Southwestern Atlantic Oceans. Samples from ribbed mussel beds were obtained from 10 sites distributed from the Peruvian coast (17°S) to the Argentinean coast (41°S). The sampling included eight beds in the Pacific and two in the Atlantic and the collections were carried out using five 0.04 m² quadrants per site. Faunal assemblages were assessed through classification analyses using binary and log‐transformed abundance data. Variation in the size and density of mussels, and in the species richness, abundance and structure of their faunal assemblages were tested using a permutational multivariate analysis of variance. Faunal assemblages showed a north–south latitudinal gradient along both the Pacific and Atlantic coasts. Binary and abundance data showed a difference in the resulting clustering arrangement of Pacific sites between 40°S and 44°S, indicating a pattern of continuity in the species distribution associated with biological substrates. At a regional scale, the distribution of species along the South American coast matched the general provincial pattern shown by prior studies, which show two biogeographic units on the Pacific coast separated by an intermediate (probably transitional) zone and a single province on the Atlantic coast extending up to Northern Argentina. Biological substrates such as ribbed mussel beds play an important ecological role by making a similar habitat type available on a large scale for a variety of invertebrate species. Despite such habitat homogeneity, however, the associated fauna exhibit marked distribution breaks, suggesting strong constraints on dispersal. This therefore suggests that macrofaunal assemblages could possibly be used as biogeographic indicators.     

Hypotaurine and thiotaurine as indicators of sulfide exposure in bivalves and vestimentiferans from hydrothermal vents and cold seeps

Vesicomyid clams, vestimentiferans, and some bathymodiolin mussels from hydrothermal vents and cold seeps possess thiotrophic endosymbionts, high levels of hypotaurine and, in tissues with symbionts, thiotaurine. The latter, a product of hypotaurine and sulfide, may store and/or transport sulfide non‐toxically, and the ratio to hypotaurine plus thiotaurine (Th/[H + Th]) may reflect an animal's sulfide exposure. To test this, we analyzed seep and vent animals with in situ sulfide measurements. Calyptogena kilmeri clams occur at high‐sulfide seeps in Monterey Canyon, while C. (Vesicomya) pacifica clams occur at seeps with lower levels but take up and metabolize sulfide more effectively. From one seep where they co‐occur, both had gill thiotaurine contents at 22–25 mmol kg⁻¹ wet mass, and while C. (V.) pacifica had a higher blood sulfide level, it had a lower Th/[H + Th] (0.39) than C. kilmeri (0.63). However, these same species from different seeps with lower sulfide exposures had lower ratios. Bathymodiolus thermophilus [East Pacific Rise (EPR 9°50′ N)] from high‐(84 μm ) and a low‐(7 μm ) sulfide vents had gill ratios of 0.40 and 0.12, respectively. Trophosomes of Riftia pachyptila (EPR 9°50′ N) from medium‐(33 μm ) and low‐(4 μm ) sulfide vents had ratios of 0.23 and 0.20, respectively (not significantly different). Ridgeia piscesae vestimentiferans (Juan de Fuca Ridge) have very different phenotypes at high‐ and low‐sulfide sites, and their trophosomes had the greatest differences: 0.81 and 0.04 ratios from high‐ and low‐sulfide sites, respectively. Thus Th/[H + Th] may indicate sulfide exposure levels within species, but not in interspecies comparisons, possibly due to phylogenetic and metabolic differences. Total H + Th was constant within each species (except in R. piscesae); the sum may indicate the maximum potential sulfide load that a species faces.     

Biologic and geologic characteristics of cold seeps in Monterey Bay, California

Cold seep communities discovered at three previously unknown sites between 600 and 1000 m in Monterey Bay, California, are dominated by chemoautotrophic bacteria (Beggiatoa sp.) and vesicomyid clams (5 sp.). Other seep-associated fauna included galatheid crabs (Munidopsis sp.), vestimentiferan worms (Lamellibrachia barhami?), solemyid clams (Solemya sp.), columbellid snails (Mitrella permodesta, Amphissa sp.), and pyropeltid limpets (Pyropelta sp.). More than 50 species of regional (i.e. non-seep) benthic fauna were also observed at seeps. Ratios of stable carbon isotopes (δ¹³C) in clam tissues near 36‰ indicate sulfur-oxidizing chemosynthetic production, rather than non-seep food sources, as their principal trophic pathway. The “Mt Crushmore” cold seep site is located in a vertically faulted and fractured region of the Pliocene Purisima Formation along the walls of Monterey Canyon ( 635 m), where seepage appears to derive from sulfide-rich fluids within the Purisima Formation. The “Clam Field” cold seep site, also in Monterey Canyon ( 900 m) is located near outcrops in the hydrocarbon-bearing Monterey Formation. Chemosynthetic communities were also found at an accretionary-like prism on the continental slope near 1000 m depth (Clam Flat site). Fluid flow at the “Clam Flat” site is thought to represent dewatering of accretionary sediments by tectonic compression, or hydrocarbon formation at depth, or both. Sulfide levels in pore waters were low at Mt Crushmore (ca 0.2 mM), and high at the two deeper sites (ca 7.011.0 mM). Methane was not detected at the Mt Crushmore site, but ranged from 0.06 to 2.0 mM at the other sites.     

南海中部上层海洋湍流混合的空间分布特征及参数化模型

通过对2010年5月南海16°N和14.5°N断面的湍流微结构剖面观测资料分析,给出了南海海盆上层湍流混合空间分布特征:在16°N断面上,上层10~400m垂向平均湍动能耗散率ερ在东侧略大于西侧;相反,在14.5°N断面上,西侧ερ均值约是东侧ερ的4倍,其中,西侧110.5°~111°E的ερ的平均值为2.6×10-6 W/m3,东侧118.5°E的ερ仅为5.89×10-7 W/m3。通过分析细结构剪切和湍流混合的相关性,发现剪切是南海中部上层强湍流混合的主要驱动力,揭示了高模态内波破碎可能是湍流混合的主要机制。另外,研究了大洋中的3种参数化模型,发现适用于大洋近海的参数化MacKinnon-Gregg(MG)模型能较好地用浮频和剪切估算南海中部深海区上层湍流耗散率。     

Effects of carbon dioxide on deep-sea harpacticoids revisited

As part of the evaluation of the environmental impact of sequestering carbon dioxide in the deep ocean, we exposed the sediment-dwelling fauna at a station in Monterey Submarine Canyon (36.378°N, 122.676°W, 3262 m) to carbon dioxide-rich seawater and found that most of the harpacticoid copepods were killed. In an expanded, follow-on experiment on the continental rise nearby (36.709°N, 123.523°W, 3607 m), not only did harpacticoids survive exposure to carbon dioxide-rich seawater, but we found no evidence from seven additional metrics that the harpacticoids had been affected. We infer that during the second experiment the harpacticoids were not exposed to a stressful dose. During the second experiment, carbon dioxide-rich seawater appears to have been produced more slowly than in the first, probably because of differences in the near-bottom flow regimes. We conclude that local physical circumstances can substantially influence the results of experiments of this type and will complicate the evaluation of the environmental consequences of deep-ocean carbon dioxide sequestration.     

Density of mud‐dwelling meiobenthos from three sites in the Wellington region

Meiobenthos from the Waiwhetu Stream (41°14.22′S, 174°54.28′E), a heavily polluted site, was low in density and numbers of species; a tubificid oligochaete Limnodrihts cf. hoffmeisteri dominated. In the Hutt River estuary (41°14.09′S, 174°53.85′E), meiofauna density was the same as in similar sediments world‐wide, but dominance by 2 species of harpacticoid copepods produced a low‐diversity assemblage. The fauna in the Pauatahanui Inlet (41°05.2′S, 174°54.05′E) was comparable in density and diversity to the faunas of muddy estuarine sediments in other parts of the world. The dominance of nematodes, abundance of Echinoderes cf. coulli (Kinorhyncha), and the variety of species suggest that the Pauatahanui site was the most normal of the 3 sampled.     

Limited phylogeographic structure for five bathyal ophiuroids at continental scales

There have been comparatively few large-scale studies on spatial genetic structure of bathyal seafloor fauna, despite the importance of these data to the successful management of the world's oceans. We use a comparative analysis of mitochondrial DNA from five bathyal (200–3500 m) species of brittle-stars (Ophiuroidea) to assess phylogeographic structure along an extensive (8000 km) longitudinal gradient at temperate latitudes (28–56°S) from south-west Australia (113°E) to seamounts east of New Zealand (175°W). We found no evidence of a genetic discontinuity between Australia and New Zealand, either across the temperate Tasman Sea or across the Southern Ocean between the South Tasman Rise and the Macquarie Ridge. However, there were latitudinal phylogeographical breaks between tropical, temperate and polar regions; longitudinal breaks across the eastern Indian Ocean; and a bathymetric break at approximately 1700 m. Although there was limited regional structure in the frequency of haplotype distributions within the major clades, and no clade appeared to be strictly panmictic, the regional structure in general was not concordant with a simple isolation-by-distance model. Demographic structure varied with three clades having a simplified haplotype network, low effective population sizes and no evidence of significant population expansion, and two clades having a high diversity of haplotypes, relatively high effective population sizes and signs of recent population expansion. These results are discussed with respect to putative dispersal strategies. We hypothesise that the ‘brooding’ species produce both brooded young and pelagic larvae, allowing for both the maintenance of local populations and long-distance dispersal.     

Latitudinal trends in the species richness of free-living marine nematode assemblages from exposed sandy beaches along the coast of Chile (18–42 °S)

The latitudinal pattern of species richness of free-living marine nematodes from exposed sandy beaches along the coast of Chile between 18 and 42° S was examined. Unlike many other examinations of latitudinal gradients, this study is not based on data mined from the literature, but on samples collected specifically to examine these themes. Five replicate quantitative 50 cm³ samples of sediment were taken from the zone of retention of 66 exposed sandy beaches. The free-living nematode fauna was identified and quantified to species level. The data were then examine using ordinary least squares and simultaneous autoregressive model (SAR_err) regression methods, examining the associations between species richness and latitude, coastline complexity, and sea surface temperature, primary productivity of the adjacent coastal waters and mean latitudinal range size. The species richness of free-living marine nematodes from exposed sandy beaches along the coast of Chile decreased with increasing latitude and was strongly associated with mean annual sea surface temperature. Mean latitudinal range size increased with increasing latitude, supporting Rapoport’s rule, and decreased with increasing species richness. The results suggest that the nematode fauna of exposed sandy beaches is derived from a low latitude fauna that has dispersed to higher latitudes, but that many species may be physiologically constrained, by temperature, from dispersing further south.     

温度对厚壳贻贝(Mytilus coruscus)鳃组织纤毛结构及摄食率的影响机制研究

纤毛是着生在贻贝鳃上感知外界物理和化学信号并帮助食物转运的一类重要细胞结构, 温度的变化会改变纤毛的形态和生理生化特征, 从而影响贻贝的摄食行为。为探究不同温度下厚壳贻贝的摄食率变化, 以及温度对纤毛的形态、酶活和相关基因表达的影响, 实验设置16、26和32 °C三种温度处理厚壳贻贝, 处理24 h后测定1 h内每个处理组的摄食率, 同时采用组织学方法对各处理组鳃上的纤毛形态结构进行观察,并测定鳃组织的抗氧化酶活力和纤毛相关基因tekt1、tekt2、tekt3、tekt4、caf58、caf100、dnah、rsph99和ift74的表达变化。实验结果显示, 32 °C处理组厚壳贻贝的摄食率显著低于其他两组(P<0.05), 且32 °C处理组贻贝鳃上的前纤毛、侧纤毛以及纤毛细胞受损严重并部分脱落, 血腔间隙破损暴露, 而其余两组鳃上纤毛形态较为正常; 不同温度处理下鳃组织的过氧化氢(H₂O₂)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)活力呈现温度特异性; 与16 °C处理组相比, 26 °C处理组中除tekt4和ndah外其他7个纤毛相关基因表达均显著上调, 32 °C处理组除tekt1外其余8个基因表达均显著下调(P<0.05)。上述结果表明, 32 °C高温处理对贻贝鳃上纤毛造成严重损伤, 导致纤毛运动、纤毛再生和纤毛感知功能均受到一定程度的抑制,从而影响食物颗粒的运输, 造成摄食率的降低。     

Dissolved and labile particulate Zr,Hf, Nb,Ta, Mo and W in the western North Pacific Ocean

Dissolved and labile particulate Zr, Hf, Nb, Ta, Mo and W were determined at stations K1 (51°N, 165°E), K2 (47°N, 160°E), KNOT (44°N, 155°E) and 35N (35°N, 160°E) in the western North Pacific Ocean. A portion of seawater for dissolved species (D) was passed through a 0.2 μm Nuclepore filter and acidified to pH 2.2 with HCl and HF. A portion of seawater for acid-dissolvable species (AD) was acidified without filtration. Labile particulate (LP) species is defined as AD minus D, which represents a chemically labile fraction of particulate species. D-Zr, Hf and Ta increase with depth, Nb shows a slight depletion in surface water, whereas Mo and W have a conservative vertical profile. The concentration range of D-Zr, Hf, Nb, Ta and W is 31–275, 0.14–0.95, 4.0–7.2, 0.08–0.29 and 40–51 pmol kg⁻¹, respectively, whereas that of Mo is 97–105 nmol kg⁻¹. LP-species of Zr, Hf and Ta account for 10–14% of AD in average and increase up to 25% below 4000 m, whereas those for Mo and W are negligible. In contrast, LP-Nb shows maxima (up to 27%) in surface water. We also found that D-Zr/Hf, Nb/Ta and Mo/W mole ratios generally increase in the order continental crust < river water < coastal sea < open ocean.     

Bottom fauna associated with mussel beds and alvinellid communities in the hydrothermal field at 9° N of the East Pacific Rise

Samples from mytilid mollusk and alvinellid polychaet communities and associated fauna were collected during cruise 49 of R/V Akademik Mstislav Keldysh at 9° N of the East Pacific Rise. The mytilids Bathymodiolus thermophylus occupied zones of diffuse releases of hydrothermal solutions with temperature anomalies a few degrees in amplitude. The alvinellid assemblages were located in the hottest parts of hydrothermal vents (～ 40°C) over sulfide mounds. The taxonomic compositions of these kinds of assemblages are different. The taxonomic richness of mytilid communities is almost twice higher. A comparison of the samples using Jaccard’s index showed a greater similarity among the alvinellid samples than that between the mytilid ones. With respect to the species number, polychaets formed the most diverse group, while gastropods were the second most diverse. The dominant species had greater proportions in alvinellid communities than in mytilid ones. This study showed great differences between the mytilid and alvinellid associations in their species composition and community structure.