Middle Ordovician reefs of Norway

The Middle Ordovician reefs of Norway were the first to develop in the western part of the Balto-scandian epicontinental sea and are the earliest coral-stromatoporoid reefs so far reported in Europe. Small patch reefs in the Steinvika Limestone, Langesund-Skien district, consist mainly of algae, echinoderms, corals and stromatoporoids. Bryozoans, molluscs, arthropods and brachiopods are also present. The reefs developed on pelmatozoan-rich substrates and are organically zoned, consisting of a pioneer community of stemmed echinoderms and sheet algae, a high-diversity intermediate community dominated by fasciculate corals and a low diversity climax community of massive corals and stromatoporoids. These communities are interpreted as the seral stages of an autogenic ecological succession. Small patch reefs are also present in the laterally equivalent Mjøsa Limestone, Toten and Nes-Hamar districts. These are organically very similar to those in the Steinvika Limestone and developed in an identical way. A large complex, consisting of several reefs, is also present in the Mjøsa Limestone. Unlike the reefs elsewhere, which developed within shallow inshore areas, this complex developed at the outer edge of the inshore shelf. The outstanding feature of the complex is the main reef forming the offshore limit which is totally dominated by stromatoporoids and lacks a sequential development. This is due to the influence of the harsher environment at the shelf edge.     

长山列岛南部三岛岩相潮间带群落多样性格局

对长山列岛南部南长山、北长山和大黑山岛屿岩相潮间带群落种类组成的调查表明,3岛屿岩礁潮间带的群落结构差异不大,表现在决定群落结构和外貌的前5位优势种群及其优势度序列基本相同;而砾石潮间带的群落结构存在一定差异,表现在北长山群落中优势种群及其优势度序列显著地区别于南长山和大黑山,但后二者趋同-3岛屿岩礁潮间带的景观和群落外貌与结构由东方小藤壶(Chthamalus chal-lengeri)、牡蛎（Ostrea spp.)、大型藻类和短滨螺(Littorina breuicula)控制,砾石潮间带则由东方小藤壶、大型藻类和平背蜞（Gaetice depressus)决定．群落多样性由物种丰富度(R)、均匀度(J)和多样性(HB、Hlv、DR、DIv)衡量,3岛屿岩礁潮间带群落的各种多样性指数呈现一致性,群落多样性以北长山最高,大黑山最低;而砾石潮间带群落的各种多样性指数存在一定差异,南长山高于北长山和大黑山,北长山潮间带群落中物种分布的均匀度最高,南长山和大黑山趋同．比较3岛屿两种基质潮间带的群落多样性发现,砾石潮间带高于岩礁潮间带。     

Occurrence of Giant Borings of Osprioneides kampto in the Lower Silurian (Sheinwoodian) Stromatoporoids of Saaremaa,Estonia

The distribution of Osprioneides is more environmentally limited than that of Trypanites in the Silurian of Baltica. Osprioneides probably occurred only in large hard substrates of relatively deepwater muddy bottom open shelf environments. Osprioneides were relatively rare, occurring in 4.7% of all stromatoporoid specimens in that environment, in contrast to small Trypanites-Palaeosabella borings, which occur in 88.4% of stromatoporoids and 88.9% of heliolitid corals. Osprioneides is reported only from the lower Sheinwoodian stromatoporoids of the exposed Silurian of Saaremaa (Wenlock to Pridoli). Osprioneides borings probably played a minor role in the general bioerosion in the Silurian of Baltica.     

Sedimentary history of Upper Silurian biostromes of Podolia (Ukraine) based on stromatoporoid morphometry

The sedimentary history of stromatoporoid biostromal accumulations reflecting various depositional conditions (autoparabiostromes and parabiostromes) is studied in two isochronous, Late Silurian carbonate sections of the Malynivtsy Formation from Podolia (western Ukraine, Kam'janec' Podil'skyj area). This study focuses on morphometrical analysis of massive stromatoporoids. Various stromatoporoid attributes, such as growth form, volume, surface character etc., are interpreted in terms of growth environments. Attributes of redeposited specimens are also analysed in terms of their susceptibility to exhumation and redeposition, and new criteria are presented in this matter. The exposed facies succession, which can be subdivided into three units: an oncolitic–fenestral complex and the stromatoporoid–coral complexes that underlie and cover it, represents the belt of shoals located at a considerable distance from shore, and its transition to a narrow zone of back-shoal tidal flats. The facies patterns proved to be strongly obscured by an intensive process of onshore redeposition of material during high energy episodes. These events caused exhumation and landward transport of stromatoporoids inhabiting soft-sediment bottoms of outer shelf areas, which were afterwards accumulated in parabiostromes in calm waters on lee side of a zone of shoals. The main process governing the distribution of redeposited stromatoporoids is fractional (weight) segregation. The high energetic events had less effect on stromatoporoid–coral autoparabiostromes that formed the zone of shoals, which were inhabited by stromatoporoids better adapted to permanent wave action, but nonetheless, they caused their partial reworking and depletion from those forms that did not resist redeposition, on one hand, and supplementation by specimens derived from offshore areas, on the other.     

Paleoecologic,temporal, and spatial analysis of early Silurian Reefs of the Chicotte Formation,Anticosti Island,Quebec, Canada

Summary Reefs of the Lower Silurian Chicotte Formation are the largest and most faunally diverse known on Anticosti Island, Quebec. They reach up to 25 m in thickness and 250 m in diameter and are present predominantly at two intervals, forming a lower and upper reef cluster. Remnants of bioherms are represented on the present-day wave-cut terrace as 60 to 100 m diameter, subcircular erosional depressions known as Philip structures or as outcrop. The bioherms were relatively low structures, with approximately 3 to 5 m maximum synoptic relief, some of which developed on hardgrounds and possible paleokarst surfaces of crinoidal wackestone and packstone. Dominant skeletal framework builders and sediment producers within all of the reefs are laminar to low domical stromatoporoids, colonial cerioid and fasciculate rugose corals, colonial tabulate corals, and cryptostome bryozoans. Vertical zonation of reef biota is evident within well-exposed reefs of the lower reef cluster. Three to four stages are recognizable:1) a low-diversity tabulate coral-dominatedpioneering community including large tabulate coral colonies (halysitids and favositids), and few stromatoporoids (clathrodictyids, ecclimadictyids), fasciculate rugosans, large generally monotypic stalked crinoids, and shelly benthos (brachiopods, few ostracodes and trilobites);2) an intermediate- to high-diversity, mixed tabulate coral-stromatoporoid-dominatedreef-core community;3) a slightly lower diversity stromatoporoid-tabulate coral-dominatedclimax community with laminar coenitids and alveolitids; and,4) in a few localities, a capping, low-diversity tabulatecoral-dominated (alveolitid and coenitid), and stromatoporoid-bearing community comprising laminar forms. Amelioration of Early Silurian climates, following Late Ordovician glaciation, allowed gradual reestablishment of extensive shallow-water reef growth, by mainly new and increasingly diverse genera and species of metazoans. Reef development within the Chicotte Formation coincided with global, widespread development of latest Llandovery and earliest Wenlock reefs in subtropical to tropical areas. Chicotte reefs have broad characteristics, in terms of overall biotic composition, vertical successions recognized, and paleogeographic setting, similar to those of equivalent and slightly younger age from intracratonic settings in Baltica (Gotland, Sweden and Estonia) and central and northern Laurentia (Midcontinent, U.S.A.; Hudson Bay, Canada; and North Greenland, Denmark).     

Symbiotic interactions in the Silurian of Baltica

Thirteen symbiotic associations occur in the Silurian of Baltica. Symbiosis was especially prominent among colonial animals, most commonly with stromatoporoids. These sponges hosted the most diverse fauna of endobiotic symbionts (including rugosans, Syringopora, ‘polychaetes’, cornulitids and lingulids). This pattern can be explained by the abundance of stromatoporoids in the Silurian of Baltica and their large skeletal volume, making them attractive hosts for smaller invertebrates. There is an evolutionary trend of an increasing number of different pairs of symbiotic taxa from the Llandovery to the Ludlow, with a remarkable increase in the Ludlow. This is likely related to an increase in the number of mutualistic taxa that could have had evolutionary advantages over organisms less amenable to symbiosis. The number of different pairs of symbiotic taxa also increased in the Wenlock, which may be linked to delayed recovery from the end‐Ordovician mass extinction.     

Cavities and cryptic faunas beneath non-reef stromatoporoids

Kershaw, Stephen 1980 10 15: Cavities and cryptic faunas beneath non-reef stromatoporoids. Lethaia , Vol. 13 , pp. 327–338. Oslo. ISSN 0024–1161.
Stromatoporoids from level-bottom shales and argillaceous limestones in the Silurian of Gotland, Sweden, form substrates for a variety of encrusting and boring organisms. Overturned stromatoporoids have encrusters and borers on both upper and lower surfaces, while coenostea preserved in situ have encrusters on both surfaces but borings on upper surfaces only. This suggests that cavities, now infilled, existed below coenostea. The stromatoporoids are isolated and not part of a reef framework where growth alone could have created overhangs and cavities. The scouring activity of currents removing sediment from around and beneath the edges of coenostea, and small current-controlled movements leaving stromatoporoids imperfectly settled on the uneven substrate or partly overlying skeletal debris, are invoked to explain the presence of cavities and hence encrusters on stromatoporoid lower surfaces. Both processes probably operated on many specimens. The lower surfaces of these stromatoporoids also show basal concavities which range from shallow to deep and reflect the topography of the substrate and the success of stromatoporoids growing on positive features from which they could shed sediment easily. Overturned stromatoporoids and coenostea with deep, encrusted, basal concavities, point to violent environmental events, such as storms, more powerful than currents producing scour and small movements of coenostea.     

Size and shape distribution of level-bottom tabulate corals and stromatoporoids (Silurian)

Baarli, B. G., Johnson, M. E. & Keilen, H. B. 1992 07 15: Size and shape distribution of level-bottom tabulate corals and stromatoporoids (Silurian).
Size and shape distribution of tabulate coral and stromatoporoid faunas were studied at two Lower Silurian sections in Norway on the Baltic platform and one section in eastern Iowa on the Laurentian platform. All the sections are dominated by storm beds with predominantly shallowing upward features; they differ from one another in clastic content and proximity to land. Most of the fauna lived below normal wave-base, but within the photic zone, on fine grained and firm bottoms. In all three localities, size clearly increases up-section for stromatoporoids, favositids, and heliolitids but it decreases for halysitids in the Oslo region. Sediment influx worked negatively on size but generally not so much as to affect average size. lurbulence in combination with decreasing sediment influx affected the size decrease in heliolitids up section. Nutrients and turbidity were of minor importance as growth controlling factors. Light intensity is the only factor that shows a pattern consistent with increased size up-section. Sediment influx alfected fauna composition and shape: heliolitids had the highest sediment tolerance and stromatoporoids had the lowest. Ragged skeletons were linked to tempestites. Corals and stromatoporoids reveal a population-specific response to environmental change, largely independent of benthic assemblage zones or communities. Tabulate corals, stromaroporaids, bathymetry, size variation. clastic input, benthic assemblages .     

Effects of Habitat-Forming Species Richness,Evenness, Identity,and Abundance on Benthic Intertidal Community Establishment and Productivity

In a context of reduced global biodiversity, the potential impacts from the loss of habitat-forming species (HFS) on ecosystem structure and functioning must be established. These species are often the main community primary producers and have a major role in the establishment of organisms through facilitation processes. This study focuses on macroalgae and mussels as HFS within an intertidal zone along the St. Lawrence estuary (Quebec, Canada). Over a 16-week period, we manipulated the in situ diversity profile (richness, evenness, identity, and abundance) of the dominant HFS (Fucus distichus edentatus, F. vesiculosus, and Mytilus spp.) in order to define their role in both the establishment of associated species and community primary production. Contrary to expectation, no general change in HFS richness, evenness, abundance, or identity on associated species community establishment was observed. However, over the study period, the HFS diversity profile modified the structure within the trophic guilds, which may potentially affect further community functions. Also, our results showed that the low abundance of HFS had a negative impact on the primary productivity of the community. Our results suggest that HFS diversity profiles have a limited short-term role in our study habitat and may indicate that biological forcing in these intertidal communities is less important than environmental conditions. As such, there was an opportunistic establishment of species that ensured rapid colonization regardless of the absence, or the diversity profile, of facilitators such as HFS.     

Effects of Intertidal Elevation on the Rockpool Ichthyofaunas of Temperate Australia

A quantitative assessment of the effects of intertidal elevation on rockpool ichthyofaunas was investigated at four locations in southeastern New South Wales, Australia. Rockpools supported high diversity and abundance of fishes mainly comprising the families Clinidae, Blennidae, Tripterygiidae, Gobiidae, Gobiesocidae and Girellidae, which are mostly permanent residents. Mean numbers of species and individuals did not differ among low, medium and high rockpools. In contrast, species composition differed among intertidal rockpool heights with pools mainly being dominated by transient and opportunist species in lower intertidal, opportunists and permanent residents in the mid intertidal, and mainly permanent residents in the high intertidal. Distribution patterns appeared to be related to the morphological and/or physiological adaptations of species to the increasingly harsh and variable environmental conditions with increasing intertidal elevation. Residential status of each species may be used as a proxy for intertidal vertical distribution although some exceptions exist, namely Girella elevata, which may posses behavioural adaptations to cope with harsh environmental conditions.     

A Diverse Assemblage of Reef Corals Thriving in a Dynamic Intertidal Reef Setting (Bonaparte Archipelago,Kimberley, Australia)

The susceptibility of reef-building corals to climatic anomalies is well documented and a cause of great concern for the future of coral reefs. Reef corals are normally considered to tolerate only a narrow range of climatic conditions with only a small number of species considered heat-tolerant. Occasionally however, corals can be seen thriving in unusually harsh reef settings and these are cause for some optimism about the future of coral reefs. Here we document for the first time a diverse assemblage of 225 species of hard corals occurring in the intertidal zone of the Bonaparte Archipelago, north western Australia. We compare the environmental conditions at our study site (tidal regime, SST and level of turbidity) with those experienced at four other more typical tropical reef locations with similar levels of diversity. Physical extremes in the Bonaparte Archipelago include tidal oscillations of up to 8 m, long subaerial exposure times (>3.5 hrs), prolonged exposure to high SST and fluctuating turbidity levels. We conclude the timing of low tide in the coolest parts of the day ameliorates the severity of subaerial exposure, and the combination of strong currents and a naturally high sediment regime helps to offset light and heat stress. The low level of anthropogenic impact and proximity to the Indo-west Pacific centre of diversity are likely to further promote resistance and resilience in this community. This assemblage provides an indication of what corals may have existed in other nearshore locations in the past prior to widespread coastal development, eutrophication, coral predator and disease outbreaks and coral bleaching events. Our results call for a re-evaluation of what conditions are optimal for coral survival, and the Bonaparte intertidal community presents an ideal model system for exploring how species resilience is conferred in the absence of confounding factors such as pollution.     

Assessing the Response of Nematode Communities to Climate Change-Driven Warming: A Microcosm Experiment

Biodiversity has diminished over the past decades with climate change being among the main responsible factors. One consequence of climate change is the increase in sea surface temperature, which, together with long exposure periods in intertidal areas, may exceed the tolerance level of benthic organisms. Benthic communities may suffer structural changes due to the loss of species or functional groups, putting ecological services at risk. In sandy beaches, free-living marine nematodes usually are the most abundant and diverse group of intertidal meiofauna, playing an important role in the benthic food web. While apparently many functionally similar nematode species co-exist temporally and spatially, experimental results on selected bacterivore species suggest no functional overlap, but rather an idiosyncratic contribution to ecosystem functioning. However, we hypothesize that functional redundancy is more likely to observe when taking into account the entire diversity of natural assemblages. We conducted a microcosm experiment with two natural communities to assess their stress response to elevated temperature. The two communities differed in diversity (high [HD] vs. low [LD]) and environmental origin (harsh vs. moderate conditions). We assessed their stress resistance to the experimental treatment in terms of species and diversity changes, and their function in terms of abundance, biomass, and trophic diversity. According to the Insurance Hypothesis, we hypothesized that the HD community would cope better with the stressful treatment due to species functional overlap, whereas the LD community functioning would benefit from species better adapted to harsh conditions. Our results indicate no evidence of functional redundancy in the studied nematofaunal communities. The species loss was more prominent and size specific in the HD; large predators and omnivores were lost, which may have important consequences for the benthic food web. Yet, we found evidence for alternative diversity–ecosystem functioning relationships, such as the Rivets and the Idiosyncrasy Model.     

Biotic structure and morphology of patch reefs from South China (Ningqiang Formation, Telychian, Llandovery, Silurian)

Summary Ningqiang Formation (late Telychian, Llandovery, Silurian), characterized by nearly 3000 m of shales in tercalated with carbonates, is situated between Ningqiang (S. Shaanxi Province) to Guangyuan (N. Sichuan Province) adjacent to the northwest margin of the Yangtze Platform. The high diversity “Xiushan Fauna”, and abundant reef development, illustrate a relatively warm and persistent shallo marine environment in these early Silurian sediments. The sequence shows reef radiation after recovery from the end Ordovician mass extinction envents. Multiple horizons of reef-building occurred within a relatively short geological interval and resulted in more than 30patch reefs up to 200 m in diameter and 1–50 m vertically, composed of abundant fossils. Reef biota include frame-building corals, stromatoporoids, bryozoans, and microbialites, and reef-associated oranisms such as crinoids, brachiopods, trilobites, gastropods, nautiloids and ostracods. Three reefrelated biotic associations are recognised: a) reefs dominated by framework with crinoids and microbia; b) reefs dominated by only crinoids and microbia; and c) crinoiddomainated facies. Seven representative reef examples illustrate different morphologies and growth styles. A high terrigenous debris input and shallow epicontinental ramp, which lacked obvious topographic variation, were major controls which resulted in rather simple reefs; sedimentation was apparently the main constraint on lateral and vertical extension of reefs, and prevented large-scale reef complexes developing.     

The non-native turf-forming alga Caulacanthus ustulatus displaces space-occupants but increases diversity

Non-indigenous seaweeds can be found in coastal habitats worldwide yet the ecological effects of only ~6 % of macroalgal introductions have been studied. The turf-forming red alga Caulacanthus ustulatus, a putative introduction from Asia, was discovered in southern California in 1999, yet has received very little attention despite being common in rocky intertidal habitats in the region. The purpose of this study was to evaluate the potential effects of Caulacanthus on native invertebrate and seaweed community composition. Macrofaunal, meiofaunal, and macroalgal community structure and diversity were compared between patches with (non-native) and without Caulacanthus (native) in the upper intertidal zone at 5 locations in southern California. Caulacanthus appears to displace macro invertebrates, such as barnacles, limpets, and periwinkles, while facilitating a more diverse array of meiofauna and macroalgae. This is likely due to the formation of a novel turf habitat in the upper zone where turfs are uncommon in this region naturally; algal turfs can increase habitat complexity, trap sediment, and maintain moisture during low tide which likely benefits meiofauna and seaweeds by providing food, habitat, or refuge from desiccation stress. Subsequent comparisons of invertebrate and seaweed assemblages were conducted in native and non-native patches at one site in the upper intertidal zone as well as in the middle intertidal zone where a native turf zone exists. Despite differences in community composition in the upper intertidal zone, no differences were observed in the middle zone, providing support that the novel turf created by Caulacanthus in the upper zone drives community differences.     

Facies and paleoecology of the late ordovician (Caradoc-Ashgill) stromatoporoid bioherms of Tasmania, Australia

Summary Stromatoporoids, together with other sedentary organisms, form bioherms in the Ordovician Gordon Group which were deposited on a carbonate platform of the Western Tasmanian Terrane. The shallow marine carbonates of the older formations show monotonous lithofacies and biota. The variety of the lithofacies and the diversity of sedentary organisms increases in the younger formations which exhibit evidence of subaerial exposure (fissure fillings and mud-cracks). These phenomena partly reflect the tectonic history of the Western Tasmania Terrane, and probably indicate a general increase in amplitude of sea-level change during the late Ordovician (Caradoc-Ashgill). The bioherms are most frequent in the uppermost horizons (the Den Formation—late Caradoc to early Ashgill?), where the outerops exhibit floatstone and bindstone fabrics. Stromatoporoids and corals construct generally small-scale (less than several meters in width and less than 1 m in height) binding structure. Based on growth forms, stromatoporoid genera are assigned to two morphotypes. Morphotype A generally shows laminar to low domical forms (low height/width ratio) exhibiting ragged margins and sediment inclusions within skeletons. In contrast, morphotype B consists of high domical growth forms (high height/width ratio) and lacks sediment inclusions. These differences in growth forms are interpreted to reflect different modes of biomineralization, together with environmental preferences of the individual organisms. Results of this study and previous publications, overall suggest a progressive development and diversification of biohermal biota in the middle to upper Ordovician of Tasmania. The scale and diversity of the Tasmanian bioherms are probably much smaller than the bioherms and reefs of the younger ages (Silurian and Devonian), and for stromatoporoids, the tendency of diversification is consistent with those of the other Ordovician sections. The Gordon Group provides useful information regarding the early evolutionary history of the Ordovician-Devonian reef-forming communities.     

相机陷阱法在潮间带底栖蟹类群落生态学中的应用研究

潮间带大型底栖动物调查是滨海湿地生物多样性监测的重要环节。目前普遍应用的传统侵入性调查方法（挖掘法、手捕法和陷阱诱捕法）存在干扰强、耗时久和劳动密集等问题,无法客观反映活动性较强的蟹类等重要功能类群的群落结构和物种多样性。对陆地野生动物研究中常用的相机陷阱法进行了符合潮间带应用条件的便携式设计,并以红树林蟹类为例,通过与3种传统侵入性调查方法进行对比,探讨相机陷阱法在潮间带底栖蟹类群落生态学研究中的应用。结果表明：（1）相机陷阱法在种群密度测定方面比挖掘法提高2.1倍,比手捕法提高10.3倍,比陷阱诱捕法提高16.3倍;（2）相机陷阱法在调查物种数方面均高于3种传统侵入性调查方法,适用于沙蟹科（Ocypodidae）和方蟹科（Grapsidae）蟹类调查;（3）相机陷阱法对个体大小选择性弱,采样更加全面;（4）相机陷阱法在群落alpha多样性（Shannon-Wiener指数）、beta多样性（样方-多度矩阵总方差Var （Y））和功能多样性（Rao二次熵和功能离散度）调查方面整体不弱于侵入性调查方法。此外,相较于侵入性调查方法,相机陷阱法对沉积物结构破坏小、不干扰蟹类群落结构,在兼顾数据丰富性的同时又具有高效性。然而,由于相机陷阱法基于蟹类底表活动性,无法适用于冬季调查、夜行性蟹类和游泳型蟹类调查。未来,相机陷阱法的发展将与基于深度学习的图像处理技术结合以满足数据处理需求。研究揭示了相机陷阱法在潮间带底栖蟹类群落中的应用优越性与局限性,为潮间带大型底栖动物群落生态学的研究提供技术支撑。     

Interactive effects of grazing and enrichment on diversity; conceptual implications of a rocky intertidal experiment

Understanding the ways in which consumers and productivity act and interact to yield differences in diversity is of primary conceptual and pragmatic importance in a world in which humans are simultaneously changing ecological communities and substantially altering the availability of nutrients. Here, I used macroalgal communities on rocky reefs to examine the effects of both limpet grazing and nutrient enrichment on algal diversity throughout almost two years of succession. The experimental design included three levels each of grazing and nutrients, with unglazed terracotta pots attached to the rock as replicate plots in a high intertidal limpet-macroalgal community. Grazing effects varied by year. During the first year, grazing effects were context-dependent with limpets resulting in lower species richness, especially at the highest level of limpet density. However, at this highest level of limpet density, high enrichment counteracted the negative effect of limpets such that diversity was similar to that in treatments with lower limpet densities. In the second year, grazing generally decreased richness, regardless of enrichment. The results of this experiment are partially consistent with the grazer-reversal hypothesis – grazing decreased richness in low nutrient conditions and this effect was neutralized (rather than reversed) under high enrichment. Inconsistencies with model predictions may be explained by the apparent unresponsiveness of algal productivity to experimental enrichment, the unique substrate-scraping feeding mechanisms of limpets, and potentially limited propagule supply.     

Predicted levels of future ocean acidification and temperature rise could alter community structure and biodiversity in marine benthic communities

A mesocosm experiment was conducted to quantify the effects of reduced pH and elevated temperature on an intact marine invertebrate community. Standardised faunal communities, collected from the extreme low intertidal zone using artificial substrate units, were exposed to one of eight nominal treatments (four pH levels: 8.0, 7.7, 7.3 and 6.7, crossed with two temperature levels: 12 and 16°C). After 60 days exposure communities showed significant changes in structure and lower diversity in response to reduced pH. The response to temperature was more complex. At higher pH levels (8.0 and 7.7) elevated temperature treatments contained higher species abundances and diversity than the lower temperature treatments. In contrast, at lower pH levels (7.3 and 6.7), elevated temperature treatments had lower species abundances and diversity than lower temperature treatments. The species losses responsible for these changes in community structure and diversity were not randomly distributed across the different phyla examined. Molluscs showed the greatest reduction in abundance and diversity in response to low pH and elevated temperature, whilst annelid abundance and diversity was mostly unaffected by low pH and was higher at the elevated temperature. The arthropod response was between these two extremes with moderately reduced abundance and diversity at low pH and elevated temperature. Nematode abundance increased in response to low pH and elevated temperature, probably due to the reduction of ecological constraints, such as predation and competition, caused by a decrease in macrofaunal abundance. This community‐based mesocosm study supports previous suggestions, based on observations of direct physiological impacts, that ocean acidification induced changes in marine biodiversity will be driven by differential vulnerability within and between different taxonomical groups. This study also illustrates the importance of considering indirect effects that occur within multispecies assemblages when attempting to predict the consequences of ocean acidification and global warming on marine communities.     

厦门潮间带春季鸟类群落的生态分析

厦门岛位于台湾海峡西部,北纬24°20′,东经118°4′左右,属典型亚热带海洋性季风气候,年平均气温208℃,年降雨量约1100ｍｍ。厦门岛三面隔海与大陆相邻,一面潮向外海;潮汐是规则的半日潮,同时具有日潮不等的特征,潮间带每日两次暴露于空气中[5]。厦门鸟类区系及生态分布情况,曾有几位国外学者做过零星考察[2,7],但未有系统专门报道。关于潮间带鸟类群落研究的国内报道也尚不多见,仅有陆健健等对东海北部的行鸟鹬群落做过研究[4]。我们于3～5月间对厦门潮间带鸟类进行了调查,目的在于初步了解厦门不同地区潮间带的鸟类种类组成和数量状况,探…     

长江口潮间带底栖生物生态及变化趋势

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