西南地区假希瓦格■类地层分布规律的研究

采用“图式对比”方法对西南地区假希瓦格类１０９种（亚种）的地层分布进行了研究，计算了这些种（亚种）的区域性地层分布延限，论述了该地假希瓦格类的地层分布规律，并根据其主要属种的地层分布初步建立了西南地区马平阶的“复合标准剖面”。研究结果表明，西南地区有关剖面马平阶底、顶界线的类生物地层对比存在较大的误差。     

西南地区假希瓦格■类地层分布规律的研究

采用“图式对比”方法对西南地区假希瓦格类１０９种（亚种）的地层分布进行了研究,计算了这些种（亚种）的区域性地层分布延限,论述了该地假希瓦格类的地层分布规律,并根据其主要属种的地层分布初步建立了西南地区马平阶的“复合标准剖面”。研究结果表明,西南地区有关剖面马平阶底、顶界线的类生物地层对比存在较大的误差。建议以贵州紫云扁平剖面作为我国马平阶的层型剖面     

华南假希瓦格䗴种级分类单元的定量厘定

本文对华南报道的假希瓦格?Pseudoschwagerina的48个种进行了分类厘定。通过搜集已发表属种的测量数据, 并重新度量部分南京地质古生物研究所标本馆的馆藏标本, 使用Past软件对这些种进行了判别分析。 通过定性及定量研究, 将其分为两个大类、9个小类。第一大类特征为壳长, 纺锤形–长纺锤形, 轴率多大于2.0, 隔壁褶皱较强; 第二大类特征为壳短, 近球形-粗纺锤形, 轴率多在2.0以下, 隔壁褶皱微弱–较强。进一步根据个体大小和幼壳特征的变化可以看出, 壳体较短的种往往具有粗纺锤形至亚球形的幼壳, 且幼壳包卷的圈数少, 仅1.5–2圈;而壳体较长的种通常具有长纺锤形–纺锤形的幼壳, 幼壳包卷圈数相对较多, 常有2–4圈。结合初房大小、幼壳特征和壳长, 第一大类和第二大类又可以细分为9个小类。     

茅口期■类动物的灭绝过程——灭绝选择性与物种个体大小关系的验证

对茅口期类动物群灭绝过程的分析揭示 ,若将类物种按壳体大小分为两类 ,从动物群物种分异度、物种净增速率的变化来看 ,大个体 (壳长 >6mm)物种与小个体 (壳长≤ 6mm)物种的灭绝过程并无明显的区别。根据壳壁等特征 ,茅口期类可分为南京类、希瓦格类、费伯克类和新希瓦格类 4个主要类群 ,各主要类群及其壳体大小不同的物种灭绝过程有明显的差异。在灭绝事件早期 ,各类群及其壳体大小不同的两类物种所受的影响有所不同。在早期的灭绝中 ,南京类、新希瓦格类、希瓦格类中壳长 >6mm和费伯克类中壳长≤ 6mm的物种显著减少 ,而希瓦格类中壳长≤ 6mm以及费伯克类中壳长 >6mm的物种则未受明显的影响。在茅口期晚期 ,由于灭绝压力的增大 ,除南京类外 ,所有类群及其物种无论个体大小均受到重创 ,导致类动物群物种分异度陡然下降研究结果证明 ,在灭绝强度较小时 ,类动物的生物学特征 ,如壳体大小、壳壁特征对物种的存活率有一定影响 ,而在集群灭绝的高峰期间 ,这些特征则不能发挥有效的作用     

重庆五布河壶穴形态及底栖动物群落特征

壶穴是水流与河床相互作用的产物,既是河床微地貌的组成部分,又是河流生态系统中特殊生境之一。本文对重庆五布河壶穴形态特征和壶穴内部底栖动物进行调查,统计分析山地河流壶穴形态特征、底栖动物群落结构及壶穴面积与底栖动物丰度的关系。结果表明:壶穴长短轴比介于1.0~1.2的比例最高,壶穴口径大多分布于10~20 cm,壶穴长轴和短轴、口径和深度存在较强的(对数)正相关关系;壶穴中共采集底栖动物34种,优势类群为四节蜉科、划蝽科、细蜉科;底栖动物功能摄食类群之间存在显著性差异,收集者数量最多,而撕食者最少。壶穴面积与底栖无脊椎动物丰度存在显著的正相关关系。     

华南晚二叠世长兴期菊石古生态初探

根据长兴期菊石的地理分布,共生生物(牙形石、放射虫)的生存环境,围岩的化学元素含量和元素间的比值,以及古地磁资料,认为该时期菊石生存的最宜环境为盐度正常、温暖、平静的浅海深处。又据长兴期菊石的本身特点——壳形、包卷程度、壳饰和壳体浮心和重心的位置,推测了它们的生活方式,并以游泳能力的强弱将其分为3类。又根据菊石的生活环境和生活方式,恢复了长兴期菊石的古生态,划分出底栖慢游和浅水游泳两种类型。     

夏秋季南黄海冷水团小型底栖动物类群组成与分布

为研究黄海冷水团对小型底栖动物的影响,分别于2013年6和11月,搭载"东方红2号"科学考察船对南黄海冷水团海域8个站位的小型底栖动物的类群组成、丰度、生物量及其与环境因子的关系进行研究.结果表明:2个航次的小型底栖动物平均丰度分别为900.8和758.4 ind·10 cm-2,平均生物量分别为886.9和615.7μg·10 cm-2.方差分析表明,两个季节8个站位间小型底栖动物的丰度和生物量均无显著差异.两个航次共鉴定出17个小型底栖动物类群,其中自由生活海洋线虫为最优势的类群,在两个航次中分别占总丰度的88.5%和94.0%.其他数量上较重要的类群还有底栖桡足类、多毛类、动吻类和介形类等.两个航次中分别有92.5%和95.4%的小型底栖动物分布在0~5 cm的表层沉积物内,线虫和桡足类分布在0~2 cm的比例分别为59.1%和78.2%.对小型底栖动物丰度和生物量、线虫和桡足类丰度与其沉积环境因子的相关分析表明,小型底栖动物的丰度和生物量与底层水温度和粉砂-粘土含量呈负相关,主要类群线虫的丰度也显示出同样的结果,另一主要类群桡足类的丰度与底层水温度、粉砂-粘土含量呈负相关,与中值粒径呈正相关.小型底栖动物群落类群组成与环境因子的BIOENV相关分析表明,小型底栖动物群落受底层水温度、底层水盐度、沉积物含水量、沉积物叶绿素a和脱镁叶绿酸含量的综合影响.     

新疆巩乃斯河枯、丰水期大型底栖动物群落结构与环境因子的关系

为探究新疆巩乃斯河的生态状况,团队先后在2018年10月(枯水期)和2019年6月(丰水期)对大型底栖动物群落和环境因子进行了调查,分析大型底栖动物群落结构、功能摄食类群、生活类型组成及其与环境因子的关系。研究河段共采集到大型底栖动物40种,隶属3门4纲8目27科,主要以节肢动物门为主,其中直突摇蚊亚科(Orthocladiinaespp.)、长跗摇蚊族(Tanytansinisp.)、四节蜉属(Baeitssp.)、亚美蜉属(Ameletussp.)和Cheilotrichiasp.是优势类群。经过分析发现枯、丰水期巩乃斯河大型底栖动物群落结构差异显著, T检验结果显示:枯水期大型底栖动物群落的生物密度和物种丰富度显著低于丰水期(P<0.05),两个时期大型底栖动物的生物多样性指数和均匀度无显著性差异(P>0.05)。巩乃斯河大型底栖动物功能摄食类群完整,枯、丰水期均以收集者为主;在生活类型方面,枯水期时固着型动物最相对丰度最大为43.20%,丰水期时蔓生型动物相对丰度最大为57.53%。经过对大型底栖动物和环境因子之间进行典范对应分析发现,水温是影响巩乃斯河大型底栖动物...     

北部湾中部海域底质沉积物中的有孔虫

本文对北部湾中部海域水深2.4m到61m、共计184个站位表层沉积物中的有孔虫进行研究。结果显示浮游有孔虫丰度非常低,种类也较稀少,仅在南侧水深较大的少数站位有发现,且含量不超过5%;而底栖有孔虫则较丰富,多数样品中以含有螺旋式与平旋式的玻璃质壳类型为主,暖水或大型底栖有孔虫分子常见。和其它海区相较而言,该海域底栖有孔虫中胶结壳类含量偏高,可能与沉积物底质颗粒较粗及海水盐度较低有关。该研究详细报道了底栖有孔虫主要属种在北部湾的分布特征。与海洋环境对比显示,水深和沉积物底质类型是影响这些属种平面分布的主要因素,而湾外温暖水团则是控制暖水种分子分布的另一重要因素。     

寒武纪早期锥管状化石Anabarites trisulcatus群居行为的计算流体力学分析

Anabarites trisulcatus是寒武纪早期一类三辐射对称的管栖生物,推测营群居的方式生活在浅海。本文对来自陕南宁强石钟沟剖面寒武系底部宽川铺组的Anabarites trisulcatus进行了计算机流体力学分析。根据化石形态构建3D模型,依据推测的生活环境设计流域参数,进行了单体与群居两种不同生活方式下的流体动力学模拟,结果表明:(1)水动力条件对于底栖Anabarites trisulcatus而言是重要的影响因素;(2)Anabarites trisulcatus以群居的方式生活阻力系数更小,更有利于生存。本文使用计算流体力学的方法对长期存在的功能和生态假说进行定量检验,是微体化石研究新思路的一次有益尝试。     

福建宁化晚石炭世有孔虫Pseudoendothyra动物群的发现及其意义

报道了福建宁化晚石炭世黄龙组下部白云岩中的Pseudoendothyra动物群,共描述鲢类化石1属21种,包括4个未定种。该动物群壳体微小,一般为扁圆形及凸镜形,轴率小于1,旋壁四层式,化石保存尚好,且具排它性分布。该动物群的发现丰富了筵类古生态学及其生物地层学研究领域的新资料。     

Calcite crystal orientation patterns in the bilayers of laminated shells of benthic rotaliid foraminifera

Shells of calcifying foraminifera play a major role in marine biogeochemical cycles; fossil shells form important archives for paleoenvironment reconstruction. Despite their importance in many Earth science disciplines, there is still little consensus on foraminiferal shell mineralization. Geochemical, biochemical, and physiological studies showed that foraminiferal shell formation might take place through various and diverse mineralization mechanisms.In this study, we contribute to benthic foraminiferal shell calcification through deciphering crystallite organization within the shells. We base our conclusions on results gained from electron backscattered diffraction (EBSD) measurements and describe microstructure/texture characteristics within the laminated shell walls of the benthic, symbiontic foraminifera: Ammonia tepida, Amphistegina lobifera, Amphistegina lessonii. We highlight crystallite assembly patterns obtained on differently oriented cuts and discuss crystallite sizes, morphologies, interlinkages, orientations, and co-orientation strengths.We show that: (i) crystals within benthic foraminiferal shells are mesocrystals, (ii) have dendritic-fractal morphologies and (iii) interdigitate strongly. Based on crystal size, we (iv) differentiate between the two layers that comprise the shells and demonstrate that (v) crystals in the septa have different assemblies relative to those in the shell walls. We highlight that (vi) at junctions of different shell elements the axis of crystal orientation jumps abruptly such that their assembly in EBSD maps has a bimodal distribution. We prove (vii) extensive twin-formation within foraminiferal calcite; we demonstrate (viii) the presence of two twin modes: 60°/[0 0 1] and 77°/~[6 –6 1] and visualize their distributions within the shells.In a broader perspective, we draw conclusions on processes that lead to the observed microstructure/texture patterns.     

Larval and juvenile gastropods from a Carboniferous black shale: palaeoecology and implications for the evolution of the Gastropoda

A horizon in the late Visean Ruddle Shale from Arkansas contains the oldest well-preserved gastropod protoconchs known from the Americas. The gastropod fauna consists of a diverse larval shell assemblage and a low diversity assemblage of juvenile gastropods that probably had a benthic life habit. Gastropod larval shells are always isolated, i.e. the gastropods did not complete their life cycle (no metamorphosis) and were unable to become benthic. This was caused by unfavorable environmental conditions on the soft muddy bottom that was probably due to anaerobic to exaerobic conditions. The absence or scarcity of bioturbation caused by invertebrate detritus or sediment feeders in both shale and concretions (formed before compaction) favored preservation of the delicate larval shells. The lack or scarcity of infauna and bioturbation as well as the low diversity of the presumed benthos supports an interpretation of a quasi-anaerobic to exaerobic benthic environment. The superbly preserved larval shells demonstrate that there are more caenogastropod clades present in the late Palaeozoic than suggested previously. Some larval shell types have an openly coiled first whorl followed by a planktotrophic larval shell; openly coiled initial whorls are unknown from modern caenogastropods. The vetigastropods have a smooth protoconch of two whorls clearly demarked from the following whorls - a pattern unknown in modern vetigastropods which have a protoconch of less than one whorl and build no larval shell during their planktonic stage. This could indicate a link between Palaeozoic vetigastropods and the caenogastropods.     

Global reductions in seafloor biomass in response to climate change

Seafloor organisms are vital for healthy marine ecosystems, contributing to elemental cycling, benthic remineralization, and ultimately sequestration of carbon. Deep‐sea life is primarily reliant on the export flux of particulate organic carbon from the surface ocean for food, but most ocean biogeochemistry models predict global decreases in export flux resulting from 21st century anthropogenically induced warming. Here we show that decadal‐to‐century scale changes in carbon export associated with climate change lead to an estimated 5.2% decrease in future (2091–2100) global open ocean benthic biomass under RCP8.5 (reduction of 5.2 Mt C) compared with contemporary conditions (2006–2015). Our projections use multi‐model mean export flux estimates from eight fully coupled earth system models, which contributed to the Coupled Model Intercomparison Project Phase 5, that have been forced by high and low representative concentration pathways (RCP8.5 and 4.5, respectively). These export flux estimates are used in conjunction with published empirical relationships to predict changes in benthic biomass. The polar oceans and some upwelling areas may experience increases in benthic biomass, but most other regions show decreases, with up to 38% reductions in parts of the northeast Atlantic. Our analysis projects a future ocean with smaller sized infaunal benthos, potentially reducing energy transfer rates though benthic multicellular food webs. More than 80% of potential deep‐water biodiversity hotspots known around the world, including canyons, seamounts, and cold‐water coral reefs, are projected to experience negative changes in biomass. These major reductions in biomass may lead to widespread change in benthic ecosystems and the functions and services they provide.     

Shell Condition and Survival of Puget Sound Pteropods Are Impaired by Ocean Acidification Conditions

We tested whether the thecosome pteropod Limacina helicina from Puget Sound, an urbanized estuary in the northwest continental US, experiences shell dissolution and altered mortality rates when exposed to the high CO₂, low aragonite saturation state (Ω_a) conditions that occur in Puget Sound and the northeast Pacific Ocean. Five, week-long experiments were conducted in which we incubated pteropods collected from Puget Sound in four carbon chemistry conditions: current summer surface (∼460–500 µatm CO₂, Ω_a≈1.59), current deep water or surface conditions during upwelling (∼760 and ∼1600–1700 µatm CO₂, Ω_a≈1.17 and 0.56), and future deep water or surface conditions during upwelling (∼2800–3400 µatm CO₂, Ω_a≈0.28). We measured shell condition using a scoring regime of five shell characteristics that capture different aspects of shell dissolution. We characterized carbon chemistry conditions in statistical analyses with Ω_a, and conducted analyses considering Ω_a both as a continuous dataset and as discrete treatments. Shell dissolution increased linearly as aragonite saturation state decreased. Discrete treatment comparisons indicate that shell dissolution was greater in undersaturated treatments compared to oversaturated treatments. Survival increased linearly with aragonite saturation state, though discrete treatment comparisons indicated that survival was similar in all but the lowest saturation state treatment. These results indicate that, under starvation conditions, pteropod survival may not be greatly affected by current and expected near-future aragonite saturation state in the NE Pacific, but shell dissolution may. Given that subsurface waters in Puget Sound’s main basin are undersaturated with respect to aragonite in the winter and can be undersaturated in the summer, the condition and persistence of the species in this estuary warrants further study.     

The structure and replenishment of rocky shore intertidal communities and biogeographic comparisons

Marine scientists have made many recent advances in understanding the connections between the structure of benthic communities, replenishment of populations through dispersal processes, and interactions with the nearshore water mass. In this review, some of the themes and models relating to these processes and interactions are discussed. Benthic–pelagic coupling models are in the early stages of development, but encompass oceanic processes such as upwelling and downwelling, the transport of larvae and their arrival back to shore to settle. Most current knowledge of these processes is based on a few taxa, especially barnacles and mussels. This is discussed with reference and comparison to macroalgae, which dominate much of the intertidal zone on temperate rocky shores, and have quite different life histories, transport and settlement processes. The role of key, habitat-dominating species is discussed, particularly their early life histories, with reference to the differences in community composition, nearshore dynamics and settlement processes in different countries. Finally, some suggestions are made for future work to fill gaps in understanding about rocky shore communities.     

Les diatomees dans l'upwelling de Cabo Frio (Bresil): liste d'especes et etude ecologique

The diatoms in the Cabo Frio (Brazil) upwelling: check listand ecological study. A qualitative and quantitative study onthe diatoms from the Cabo Frio area was made and a check listproduced. Sampling was carried out over one year at an anchoragestation in the upwelling zone. Data were analysed by means ofa multivariate statistical method, in order to show the mainsynecological aspects of the diatom populations. Diatoms dominatein most samples, except in the Brazil current water where dinoflagellatesare dominant, and where there is a poor population of thermophilicdiatoms. Recently upwelled water has a poor phytoplankton composedof epiphytic and benthic species; these are substituted by intenseblooms of neritic and opportunist diatoms when the temperaturerises. The annual distribution of the diatoms accompanies theoccurrence of upwelling. The vertical thermal gradient or waterstability is the most important factor affecting the specificcomposition and distribution of the diatom communities.     

The feeding, growth, and energetics of two rocky intertidal predators (Pisaster ochraceus and Nucella canaliculata) under water temperatures simulating episodic upwelling

Although most upwelling regions are marked by strong fluctuations in water temperature, few studies have examined how episodic cold-water events affect the physiology and ecology of benthic marine invertebrates. I tested the hypothesis that upwelling-related variation in water temperature regulates the feeding, growth, and energetics of two rocky intertidal predators, the sea star Pisaster ochraceus (Brandt, 1835) and the whelk Nucella canaliculata (Duclos, 1832). Sea stars and whelks were maintained in laboratory tanks at a constant 9 °C, a constant 12 °C, and a treatment that simulated the Oregon coast upwelling regime by cycling between 14-day periods of 12 and 9 °C. Early in the experiments, sea stars and whelks held at 9 °C consumed about 30% fewer mussels (Mytilus trossulus) than those in warmer tanks. Despite lower consumption by whelks in colder tanks, 9 and 12 °C individuals attained the same final size. Similarly, sea stars in 9 °C tanks showed greater growth per gram of mussel tissue consumed than individuals held at 12 °C. These results suggest that reduced consumption under colder conditions was balanced by reduced metabolic costs. Moreover, there appeared to be an energetic advantage to living in the temperature regime characteristic of intermittent upwelling. Sea stars alternately exposed to 12 and 9 °C had a significantly higher growth rate, conversion efficiency, and storage of reserves in the pyloric caeca than individuals in the constant 12 °C tanks. Whelks maintained under fluctuating temperatures tended to grow faster than those held at constant 12 or 9 °C, although this trend was not statistically significant (p=0.069). These results suggest that benthic consumers experiencing cyclic temperatures may feed intensely during periods of warmer water while benefiting from reduced metabolic costs during cold-water intrusions. Because the fecundity of Pisaster and Nucella is a function of energy stored during the upwelling season, interannual variability in upwelling patterns could alter the reproductive output of these species.     

A part of the Japan Sea form of the threespine stickleback, Gasterosteus aculeatus, spawns in the seawater tidal pools of western Hokkaido Island, Japan

The Japan sea form of the threespine stickleback, Gasterosteus aculeatus, was found to spawn in the seawater tidal pool of the Cape Benkei, western Hokkaido Island, Japan, in 2001 and 2003. Nest-guarding males, adult females and juveniles of this form were also observed in four tidal pools of the Capes Benkei, Kabuto and Kamui, in 2001–2003. Otolith Sr:Ca ratios in sticklebacks collected from these tidal pools were relative high from the core to the edge, suggesting they lived in seawater environments throughout its life cycle. These findings suggest that a part of the Japan Sea formȁ9s individuals in western Hokkaido Island have the potential to breed in the coastal sea and the life history style has evolved in dependence on the seawater environment.     

Life habit and ontogeny of the unusual arcid bivalve Ambrogia mytiloides (Brocchi, 1814)

The unusual Plio-Pleistocene arcid Ambrogia mytiloides (Brocchi, 1814) has a large, elongate, smooth and streamlined shell. On the basis of these characters and the occurrence of moderate shell torsion, the mode of life of this species was formerly thought to be semi-infaunal endobyssate, obliquely oriented like the twisted arcid Trisidos. The discovery of shells in life position suggests that this species lived in a subvertical position. Rather than a recliner, this arcid was then a sticker, whose stability was provided by the byssus, which also was used to aid the bivalve in burrowing, and by its large size. The morphology of juvenile valves, smaller than 4 mm, suggests an epibyssate mode of life in its early growth stages. Ambrogia represents a remarkable pathway in the secondary return of arcids to soft bottoms: with this genus, they reached their deepest burrowing level. However, this strategy was not very successful, probably because of evolutionary constraints on the Arcoida.