Effects of different components of diversity on productivity in artificial plant communities

In an experiment on artificial plant communities, the effects of three components of plant diversity—plant species diversity, plant functional group diversity and plant functional diversity—on community productivity and soil water content were compared. We found that simple regression analysis showed a positive diversity effect on ecosystem processes (productivity and soil water content). However, when three components of diversity were included in the multiple regression analyses, the results showed that functional group diversity and functional diversity had more important effects on productivity and resource use efficiency. These results suggested that, compared with species number, functional differences among species and the range of functional traits carried by plants are the basis of biodiversity effects on ecosystem functioning. These diversity effects of increasing functional group diversity or functional diversity were likely because species differing greatly in size, life form, phenology and capacity to capture and use resources efficiently in diverse communities realize complementary resource use in temporal, spatial, and biological ways.     

生物多样性与稳定性机制研究进展

随着全球生物多样性的迅速丧失,生物多样性与生态系统稳定性的关系已成为人类面临的重要科学问题。许多研究表明生物多样性与稳定性存在正相互关系,但其内在机制尚不能被很好地理解并且存在争议。对生物多样性与稳定性的研究历史做简短的回顾,然后根据时间稳定性的计算方法将时间稳定性分为平均值、方差之和以及协方差之和3个统计组成部分,在此基础上对现在常见的生物多样性-稳定性机制进行分类和详细介绍。并对现在生物多样性和稳定研究的争论进行总结。建议未来生物多样性稳定性关系的研究应该建立更加综合的理论,增加实验时间,应用整合分析(meta-analysis)对已发表实验结果进行综合分析,此外,应多关注非生物量/多度的属性,控制物种属性而不是仅仅控制物种的数量。     

The Biodiversity of the Mediterranean Sea: Estimates,Patterns, and Threats

The Mediterranean Sea is a marine biodiversity hot spot. Here we combined an extensive literature analysis with expert opinions to update publicly available estimates of major taxa in this marine ecosystem and to revise and update several species lists. We also assessed overall spatial and temporal patterns of species diversity and identified major changes and threats. Our results listed approximately 17,000 marine species occurring in the Mediterranean Sea. However, our estimates of marine diversity are still incomplete as yet—undescribed species will be added in the future. Diversity for microbes is substantially underestimated, and the deep-sea areas and portions of the southern and eastern region are still poorly known. In addition, the invasion of alien species is a crucial factor that will continue to change the biodiversity of the Mediterranean, mainly in its eastern basin that can spread rapidly northwards and westwards due to the warming of the Mediterranean Sea. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to gaps in our knowledge of the biota along the southern and eastern rims. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. At present, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats and affect the greatest number of taxonomic groups. All these impacts are expected to grow in importance in the future, especially climate change and habitat degradation. The spatial identification of hot spots highlighted the ecological importance of most of the western Mediterranean shelves (and in particular, the Strait of Gibraltar and the adjacent Alboran Sea), western African coast, the Adriatic, and the Aegean Sea, which show high concentrations of endangered, threatened, or vulnerable species. The Levantine Basin, severely impacted by the invasion of species, is endangered as well.This abstract has been translated to other languages (File S1).     

Potentials for monitoring gene level biodiversity: using Sweden as an example

Programs for monitoring biological diversity over time are needed to detect changes that can constitute threats to biological resources. The convention on biological diversity regards effective monitoring as necessary to halt the ongoing erosion of biological variation, and such programs at the ecosystem and species levels are enforced in several countries. However, at the level of genetic biodiversity, little has been accomplished, and monitoring programs need to be developed. We define “conservation genetic monitoring” to imply the systematic, temporal study of genetic variation within particular species/populations with the aim to detect changes that indicate compromise or loss of such diversity. We also (i) identify basic starting points for conservation genetic monitoring, (ii) review the availability of such information using Sweden as an example, (iii) suggest categories of species for pilot monitoring programs, and (iv) identify some scientific and logistic issues that need to be addressed in the context of conservation genetic monitoring. We suggest that such programs are particularly warranted for species subject to large scale enhancement and harvest—operations that are known to potentially alter the genetic composition and reduce the variability of populations.     

Genetic biodiversity in the Baltic Sea: species-specific patterns challenge management

Information on spatial and temporal patterns of genetic diversity is a prerequisite to understanding the demography of populations, and is fundamental to successful management and conservation of species. In the sea, it has been observed that oceanographic and other physical forces can constitute barriers to gene flow that may result in similar population genetic structures in different species. Such similarities among species would greatly simplify management of genetic biodiversity. Here, we tested for shared genetic patterns in a complex marine area, the Baltic Sea. We assessed spatial patterns of intraspecific genetic diversity and differentiation in seven ecologically important species of the Baltic ecosystem—Atlantic herring (Clupea harengus), northern pike (Esox lucius), European whitefish (Coregonus lavaretus), three-spined stickleback (Gasterosteus aculeatus), nine-spined stickleback (Pungitius pungitius), blue mussel (Mytilus spp.), and bladderwrack (Fucus vesiculosus). We used nuclear genetic data of putatively neutral microsatellite and SNP loci from samples collected from seven regions throughout the Baltic Sea, and reference samples from North Atlantic areas. Overall, patterns of genetic diversity and differentiation among sampling regions were unique for each species, although all six species with Atlantic samples indicated strong resistence to Atlantic-Baltic gene-flow. Major genetic barriers were not shared among species within the Baltic Sea; most species show genetic heterogeneity, but significant isolation by distance was only detected in pike and whitefish. These species-specific patterns of genetic structure preclude generalizations and emphasize the need to undertake genetic surveys for species separately, and to design management plans taking into consideration the specific structures of each species.     

Fisheries management and conservation in the Irish Sea

The Irish Sea ia a relatively small, enclosed sea area which is subject to a wide range of human uses including navigation, oil terminals, dumping of sewage and industrial sludge, cooling for nuclear power stations, gravel extraction, gas and oil prospecting and fishing. Commercial fishing is affected by the other uses and at the same time it provides a means of monitoring their effects on a part of the ecosystem. Regular samples taken from fish markets provide a long series of age-composition data of the main commercial species — cod, whiting, plaice and sole — from which population changes can be assessed. More recently groundfish trawl surveys have been carried out to provide more detailed information on the distribution of all demersal fish species seasonally and in relation to area, depth and sediment type. Advice on the management of commercial fish species is prepared by a working group of the International Council for the Exploration of the Sea (ICES), and is based mainly on analytical single-species models. There are obvious shortcomings of such models in an area of mixed fishery and high diversity such as the Irish Sea. The objectives adopted in these models and in fisheries management generally are examined critically in relation to the possible aims of conservation.     

Theory predicts a rapid transition from niche-structured to neutral biodiversity patterns across a speciation-rate gradient

A central challenge in community ecology is to predict patterns of biodiversity with mechanistic models. The neutral model of biodiversity is a simple model that appears to provide parsimonious and accurate predictions of biodiversity patterns in some ecosystems, even though it ignores processes such as species interactions and niche structure. In a recent paper, we used analytical techniques to reveal why the mean predictions of the neutral model are robust to niche structure in high diversity but not low-diversity ecosystems. In the present paper, we explore this phenomenon further by generating stochastic simulated data from a spatially implicit hybrid niche-neutral model across different speciation rates. We compare the resulting patterns of species richness and abundance with the patterns expected from a pure neutral and a pure niche model. As the speciation rate in the hybrid model increases, we observe a surprisingly rapid transition from an ecosystem in which diversity is almost entirely governed by niche structure to one in which diversity is statistically indistinguishable from that of the neutral model. Because the transition is rapid, one prediction of our abstract model is that high-diversity ecosystems such as tropical forests can be approximated by one simple model—the neutral model—whereas low-diversity ecosystems such as temperate forests can be approximated by another simple model—the niche model. Ecosystems that require the hybrid model are predicted to be rare, occurring only over a narrow range of speciation rates.     

Biodiversity and ecosystem functioning: recent theoretical advances

The relationship between biodiversity and ecosystem functioning has emerged as a major scientific issue today. As experiments progress, there is a growing need for adequate theories and models to provide robust interpretations and generalisations of experimental results, and to formulate new hypotheses. This paper provides an overview of recent theoretical advances that have been made on the two major questions in this area: (1) How does biodiversity affect the magnitude of ecosystem processes (short‐term effects of biodiversity)? (2) How does biodiversity contribute to the stability and maintenance of ecosystem processes in the face of perturbations (long‐term effects of biodiversity)?
Positive short‐term effects of species diversity on ecosystem processes, such as primary productivity and nutrient retention, have been explained by two major types of mechanisms: (1) functional niche complementarity (the complementarity effect), and (2) selection of extreme trait values (the selection effect). In both cases, biodiversity provides a range of phenotypic trait variation. In the complementarity effect, trait variation then forms the basis for a permanent association of species that enhances collective performance. In the selection effect, trait variation comes into play only as an initial condition, and a selective process then promotes dominance by species with extreme trait values. Major differences between within‐site effects of biodiversity and across‐site productivity–diversity patterns have also been clarified. The local effects of diversity on ecosystem processes are expected to be masked by the effects of varying environmental parameters in across‐site comparisons.
A major reappraisal of the paradigm that has dominated during the last decades seems necessary if we are to account for long‐term effects of biodiversity on ecosystem functioning. The classical deterministic, equilibrium approaches to stability do not explain the reduced temporal variability of aggregate ecosystem properties that has been observed in more diverse systems. On the other hand, stochastic, nonequilibrium approaches do show two types of biodiversity effects on ecosystem productivity in a fluctuating environment: (1) a buffering effect, i.e., a reduction in the temporal variance; and (2) a performance‐enhancing effect, i.e., an increase in the temporal mean. The basic mechanisms involved in these long‐term insurance effects are very similar to those that operate in short‐term biodiversity effects: temporal niche complementarity, and selection of extreme trait values. The ability of species diversity to provide an insurance against environmental fluctuations and a reservoir of variation allowing adaptation to changing conditions may be critical in a long‐term perspective.
These recent theoretical developments in the area of biodiversity and ecosystem functioning suggest that linking community and ecosystem ecology is a fruitful avenue, which paves the way for a new ecological synthesis.     

Deep-sea nematode biodiversity in the Mediterranean basin: testing for longitudinal, bathymetric and energetic gradients

The knowledge of the processes controlling the spatial distribution of species diversity is one of the main challenges of the present ecological research. Spatial patterns of benthic biodiversity in the deep sea are poorly known in comparison with other ecosystems and this limits our understanding of the mechanisms controlling the distribution and maintenance of high biodiversity in the largest ecosystems of our biosphere. Although the Mediterranean basin covers <1% of the world ocean surface, none the less it hosts >7.5% of the global biodiversity. The high biogeographic complexity and the presence of steep ecological gradients contribute in making the Mediterranean a region of very high diversity. Here we report the results of an investigation on the patterns of nematode biodiversity in the deep-Mediterranean Sea, in relation with bathymetric, longitudinal and energetic gradients. Our results indicate that benthic biodiversity in the deep-Mediterranean decreases significantly with increasing depth. Moreover, at equally deep sites, nematode diversity decreased from the western to the eastern basin and longitudinal gradients were evident when comparing sites at 4000-m depth, with 3000-m depth. The analysis of the available energy (measured as labile organic matter content of the sediments) suggests that biodiversity patterns are not controlled by the amounts of food resources, but instead bio-availability is the key factor. A more detailed analysis revealed an extremely high deep-sea beta-diversity (turnover diversity), both among sites at different depths as well as at similar depths of different longitude or within the same basin. This new finding has not only important implications on the estimates of the overall regional diversity (gamma diversity), but also suggests the presence of high biogeographic complexity in the deep benthic domain of the Mediterranean Sea.     

热带珊瑚礁区海参的生境选择与生态作用

珊瑚礁生态系统是一个高生产力、高生物多样性的特殊海洋生态系统,具有为生物提供栖息地、参与生物地球化学循环、防浪护岸、指示水体污染程度等生态功能。珊瑚礁生态系统的突出特点是其生境异质性很高,各种各样的生境斑块为种类繁多、习性各异的游泳和底栖生物提供栖息场所,这些礁栖生物通过参与各项生态过程而形成各种特定的功能群,共同完成重要的生态功能。在热带珊瑚礁生态系统中,海参是大型底栖动物区系的重要一员。种类繁多的海参具有各自不同的生境选择特征,通过摄食、运动等行为活动发挥着改良底质、促进有机物矿化和营养盐再生等生态作用。近几年来,全球热带海参受人类过度捕捞和珊瑚礁退化的影响而面临资源衰退、物种多样性丧失等问题,深入认识其生态学功能、加强热带海参资源保护迫在眉睫。综述了国内外热带珊瑚礁海参的基础生态学研究进展：海参对珊瑚礁生境斑块呈现显著的偏好选择特征以及种间差异和季节变动,不同生境斑块的食物质量、底质类型和水动力条件是影响海参生境偏好的重要因素;海参通过生物扰动可以改变珊瑚礁生境沉积物的含水量、渗透性、颗粒组成、再矿化率、无机营养物质释放速率以及孔隙水的化学梯度,并增加沉积物中的溶氧浓度、促进溶解...     

Identifying priority sites for the conservation of freshwater fish biodiversity in a Mediterranean basin with a high degree of threatened endemics

The Guadiana River basin’s freshwater fish species richness, endemicity and threatened status (92% of native species are threatened) highlight the need for a large-scale study to identify priority areas for their conservation. One of the most common problems in conservation planning is the assessment of a site’s relative value for the conservation of regional biodiversity. Here we used a two-tiered approach, which integrates an assessment of biodiversity loss and the evaluation of conservation value through site-specific measures. These measures based on the reference condition approach introduce the ability to make objective comparisons throughout the Guadiana River basin, thus avoiding a priori target areas. We identified a set of biodiversity priority areas of special conservation significance—which contain rare taxa as well as intact fish communities—because of their outstanding contribution to the basin’s biodiversity. The inclusion of complete sub-basins in these priority areas might guarantee an optimal solution in terms of spatial aggregation and connectivity. However, the high spatial fragmentation to which the Guadiana River basin is submitted due to river regulation highlights the necessity of a systematic approach to evaluate the capability of the identified priority areas to maintain the Guadiana’s freshwater fish biodiversity. Handling editor: R. H. Norris     

The problem of invaders in the Caspian Sea in the context of the findings of new zoo- and phytoplankton species from the Black Sea

In April 2004, an expedition to the Caspian Sea discovered the species in the Middle Caspian not previously described in this sea. These species preliminary identified as Oithona similis Claus 1963, Sagitta setosa Muller 1847, and Calanus euxinus (Hulsemann) are the main representatives of edible plankton of the Black Sea; most likely they were introduced into the Caspian Sea with ballast waters of ships passing through the Volga-Don Canal. At present, it is difficult to say if these species will be established in the Caspian Sea; if so, they will clearly become a valuable food resource for planktophagous fish in the Caspian Sea. In addition, we discovered two diatom species typical for the Black Sea phytoplankton, Pseudo-nitzschia seriata (Cleve) H. Peragallo and M. Peragallo and Cerataulina pelagica (Cleve) Hendey which invaded the Caspian Sea in recent years. Pseudo-nitzschia seriata synthesizes a toxin (domoic acid) and can become harmful for the basin in the case of mass bloom. We discuss the problem of spontaneous invasion of alien species from the Black Sea and their effect on the Caspian ecosystem in the context of these findings.Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 1, 2005, pp. 78–87.Original Russian Text Copyright © 2005 by Shiganova, Musaeva, Pautova, Bulgakova.     

Influence of occupation history and habitat on Washington sea otter diet

Habitat characteristics are primary determinants of nearshore marine communities. However, biological drivers like predation can also be important for community composition. Sea otters (Enhydra lutris ssp.) are a salient example of a keystone species exerting top‐down control on ecosystem community structure. The translocation and subsequent population growth and range expansion of the northern sea otter (Enhydra lutris kenyoni) in Washington State over the last five decades has created a spatio‐temporal gradient in sea otter occupation time and density, and acts as a natural experiment to quantify how sea otter population status and habitat type influence sea otter diet. We collected focal observations of sea otters foraging at sites across the gradient in varying habitat types between 2010 and 2017. We quantified sea otter diet composition and diversity, and long‐term rates of energy gain across the gradient. We found that sea otter diet diversity was positively correlated with cumulative sea otter density, while rate of energy gain was negatively correlated with cumulative density. Additionally, we found that habitat type explained 1.77 times more variance in sea otter diet composition than sea otter cumulative density. Long‐term diet studies can provide a broader picture of sea otter population status in Washington State.     

Young-of-the-year fish assemblages as an alternative to adult fish monitoring for ecological quality evaluation of running waters

Studies on the Upper Mississippi River, particularly over the last 15 years, have contributed to our understanding of trophic processes in large rivers. The framework established by earlier population-specific studies, however, cannot be overlooked. Examination of the feeding habits of fish ranging from planktivores to piscivores gave the first indication that trophic processes were influenced by the spatial complexity and annual hydrological patterns of river-floodplain ecosystems. Experimental studies, which have often been considered impossible or impractical in large rivers, demonstrated the potential for biotic controls of system dynamics through predator–prey and competitive interactions. Such studies have been particularly helpful in understanding the potential impact of non-native species, including zebra mussels and Asian carp, to biodiversity and secondary production. Our understanding of riverine ecosystem function expanded greatly as food web studies began the application of a new tool—natural stable isotopes. Studies employing stable isotopes illustrated how food webs in a number of large rivers throughout the world are supported by the autochthonous production of microalgae. This study, coupled with other studies testing the prevailing models of riverine ecosystem function, has brought us to a point of better understanding the nature of river ecosystem functions. It is through looking back at the earlier studies of fish diet that we should realize that the temporal and spatial complexities of river ecosystem function must still be addressed more fully. This and a better grasp of the significance of the arrangement of patches within the riverine landscape will prove beneficial, as we assess the appropriate scale of river rehabilitation with an eye on how rehabilitation promotes productivity within complex ecosystems, including the Upper Mississippi River.     

Identification of potential recruitment bottlenecks in larval stages of the giant fan mussel <Emphasis Type="Italic">Pinna nobilis</Emphasis> using specific quantitative PCR

The largest semi-enclosed basin in the world, the Mediterranean Sea, is characterized by high biodiversity and heavy human pressure on the coastal system. The Strait of Sicily (SoS) represents the boundary between western and eastern Mediterranean sub-regions and is an important biodiversity hot spot. Given its ecotonal nature and it being a “crossroad” for the westward expansion of warm-temperate and tropical species from the Levantin basin, the SoS is likely to play a key role in future climate change related biodiversity changes within the Mediterranean. The complexity of the SoS ecosystem, characterized by wider shallow detritic and rocky banks on the continental shelf hosting large biodiverse communities, and peculiar circulation pattern, promotes species diversity and abundance. In addition, the deep-sea is characterized by the occurrence of extremely vulnerable habitats, such as deep-water communities of scleractinian corals, antipatharians, gorgonians, and red coral. We review the current knowledge on the main characteristics of the north sector of the SoS ecosystem. The SoS ecosystem is increasingly threatened by expanding anthropogenic pressures in the area and specific conservation measures should be implemented on a national and international level to protect the relevant and vulnerable habitats.     

Temporal and spatial changes in benthic invertebrate trophic networks along a taxonomic richness gradient

Species interactions underlie most ecosystem functions and are important for understanding ecosystem changes. Representing one type of species interaction, trophic networks were constructed from biodiversity monitoring data and known trophic links to assess how ecosystems have changed over time. The Baltic Sea is subject to many anthropogenic pressures, and low species diversity makes it an ideal candidate for determining how pressures change food webs. In this study, we used benthic monitoring data for 20 years (1980–1989 and 2010–2019) from the Swedish coast of the Baltic Sea and Skagerrak to investigate changes in benthic invertebrate trophic interactions. We constructed food webs and calculated fundamental food web metrics evaluating network horizontal and vertical diversity, as well as stability that were compared over space and time. Our results show that the west coast of Sweden (Skagerrak) suffered a reduction in benthic invertebrate biodiversity by 32% between the 1980s and 2010s, and that the number of links, generality of predators, and vulnerability of prey have been significantly reduced. The other basins (Bothnian Sea, Baltic Proper, and Bornholm Basin) do not show any significant changes in species richness or consistent significant trends in any food web metrics investigated, demonstrating resilience at a lower species diversity. The decreased complexity of the Skagerrak food webs indicates vulnerability to further perturbations and pressures should be limited as much as possible to ensure continued ecosystem functions.     

Phylogeography of noble crayfish (Astacus astacus) reveals multiple refugia

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Past, current, and future of the central European corridor for aquatic invasions in Belarus

We analyzed the role of the waterways of Belarus in the spread of aquatic exotic invertebrates through the central European invasion corridor. Present day Belarus became critically important when in the end of the 18th—beginning of the 19th century three interbasin canals connecting rivers from the Black and Baltic seas basins were constructed for international trade. These canals became important pathways facilitating the spread of aquatic alien species. For more than a hundred years, only Ponto-Caspian species colonized Belarus using ships and especially timber in rafts exported by Russia into Western Europe. In the second half of the 20th century, new vectors of spread appeared in Belarus, such as stocking of economically important invertebrates and accidental introductions. This paper is the first comprehensive review of aquatic exotic invertebrates in Belarus. Currently, 19 exotic aquatic invertebrates are known in Belarus, including 14 species of Ponto-Caspian origin. The rate of spread of aquatic invasive species in the second half of the 20th century increased 7-fold compared to the 19th—beginning of the 20th century. We found a significant positive correlation between the time since initial invasion and number of waterbodies colonized. We predict a further increase in the rate of colonization of Belarus by exotic invertebrates as well as an increase in the diversity of vectors of spread and donor areas of alien species, especially when the ongoing reconstruction of the interbasin canals will be completed and the hydrological connection between Black Sea and Baltic Sea basins will be reestablished after an interruption that has lasted for almost a century.     

Linking Freshwater Flows and Ecosystem Services Appropriated by People: The Case of the Baltic Sea Drainage Basin

Humanity's dependence on ecosystem support is “mentally hidden” to large segments of society; it has no price in the market and is seldom accounted for in decision making. Similarly, the needs of ecosystems for fresh water for generation of nature's services are largely invisible. Freshwater assessments predominantly have focused on human uses of liquid water in rivers, lakes, and reservoirs. We estimated the spatial appropriation of terrestrial and marine ecosystems—the ecological footprint—of the 85 million inhabitants in the Baltic Sea drainage basin with regard to consumption of food and timber and waste assimilation of nutrients and carbon dioxide. We also estimated the amount of fresh water—the water vapor flow—that the inhabitants depend upon for their appropriation of these ecosystem services. The ecological footprint estimate corresponds to an area as large as 8.5–9.5 times the Baltic Sea and its drainage basin with a per capita ecosystem appropriation of 220,000–250,000 m². This large estimate is mainly attributed to carbon sequestering by marine ecosystems and forests. The water vapor flow of the ecological footprint of forests, wetlands, agriculture, and inland water bodies for making the human appropriation of ecosystem services possible is estimated at 1175–2875 km³ y⁻¹. Human dependence on water vapor flows for ecosystem services is as great as 54 times the amount of freshwater runoff that is assessed and managed in society. Decision making on an increasingly human-dominated planet will have to address explicitly the critical interdependencies between freshwater flows and the capacity of ecosystems to generate services. We advocate a dynamic ecohydrological landscape-management approach upstream and downstream in watersheds to reduce unintentional impacts, irreversible change, and further loss of freshwater resources, ecosystem services, and resilience. Received 6 October 1998; accepted 30 March 1999.