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1.
Nick Tolimieri Jameal F. Samhouri Victor Simon Blake E. Feist Phillip S. Levin 《Ecosystems》2013,16(7):1216-1229
Mean trophic level (MTL) is one of the most widely used indicators of marine ecosystem health. It usually represents the relative abundance of fished species across a spectrum of TLs. The reality, ubiquity, and causes of a general decline in the MTL of fisheries catch through time, and whether fisheries catch tracks ecosystem level changes, have engendered much attention. However, the consequences of such patterns for broader ecosystem structure and function remain virtually unexplored. Along the Pacific U.S. Coast, previous work has documented fluctuations and a slow increase in ecosystem MTL from 1977 to 2004. Here, we document a decline in the ecosystem MTL of groundfishes in the same ecosystem from 2003 to 2011, the proximate cause of which was a decrease in the biomass of higher TL groundfishes. Using a food web model, we illustrate how these shifts in ecosystem structure may have resulted in short term, positive responses by many lower TL species in the broader ecosystem. In the longer term, the model predicts that initial patterns of prey release may be tempered in part by lagged responses of other higher TL species, such as salmon and seabirds. Although ecosystem functions related to specific groups like piscivores (excluding high-TL groundfishes) changed, aggregate ecosystem functions altered little following the initial reorganization of biomass, probably due to functional redundancy within the predator guild. Efforts to manage and conserve marine ecosystems will benefit from a fuller consideration of the information content contained within, and implied by, fisheries-independent TL indicators. 相似文献
2.
Competition between marine mammals and fisheries for marine resources-whether real or perceived-has become a major issue for several countries and in international fora. We examined trophic interactions between marine mammals and fisheries based on a resource overlap index, using seven Ecopath models including marine mammal groups. On a global scale, most food consumed by marine mammals consisted of prey types that were not the main target of fisheries. For each ecosystem, the primary production required (PPR) to sustain marine mammals was less than half the PPR to sustain fisheries catches. We also developed an index representing the mean trophic level of marine mammal's consumption (TL(Q)) and compared it with the mean trophic level of fisheries' catches (TL(C)). Our results showed that overall TL(Q) was lower than TL(C) (2.88 versus 3.42). As fisheries increasingly exploit lower-trophic level species, the competition with marine mammals may become more important. We used mixed trophic impact analysis to evaluate indirect trophic effects of marine mammals, and in some cases found beneficial effects on some prey. Finally, we assessed the change in the trophic structure of an ecosystem after a simulated extirpation of marine mammal populations. We found that this lead to alterations in the structure of the ecosystems, and that there was no clear and direct relationship between marine mammals' predation and the potential catch by fisheries. Indeed, total biomass, with no marine mammals in the ecosystem, generally remained surprisingly similar, or even decreased for some species. 相似文献
3.
La Guajira is an exploited tropical upwelling ecosystem in the Colombian Caribbean coast. A trophic model of 27 functional groups was constructed using the ECOPATH 5.0 Beta software to integrate the available information on the ecosystem. The model allowed a comparison with other trophic flow models of upwelling ecosystems. Total system biomass (68 t/km2/year), net system production (1,248.5 t/km2/year), and total system throughput (3,275 t/km2/year) make La Guajira moderate when compared with other systems. The largest amount of energy throughput is achieved from trophic level I to II (68.93 %), although an important proportion of the total flow originates from detritus (32 %). The production/respiration ratio exceeds 1, suggesting that La Guajira is an immature ecosystem and is in development, as determined by its low ascendency (33.7 %) and high development capacity (66.3 %), similar to other upwellings that have values of ascendency between 20 % and 35 %. Although the basic input data were good and covered 1995 to 2000, appropriate information is still not available on some trophic groups such as biomass (for phytoplankton, invertebrates, catfishes and pelagic predator fishes), secondary production data (invertebrates, pelagic predator fishes, and small pelagic fishes), and seabird and mammal populations, which are top trophic levels and an essential part of upwelling ecosystems. 相似文献
4.
Three indicators quantifying interactions between species are developed for an upwelling system to provide useful measures for the comparison of marine ecosystem structure and function. Small pelagic fish are dominant in upwelling systems, and by definition, they are pivotal in a wasp-waist upwelling system. The indicator of interaction strength (IS) quantifies the effect that a change in biomass of one group has on abundance of other groups. The functional impact (FI) indicator quantifies the trophic impacts of species on their own and other functional groups or feeding guilds. The trophic replacement (TR) indicator quantifies the trophic similarity between a species that is removed from an ecosystem and other species in that ecosystem, i.e. it quantifies the ability of one group to trophically replace another. A trophic model of the southern Benguela ecosystem is used as an example for the application of the indicators. The strong similarities in trophic functioning of the southern Benguela ecosystem in the anchovy-dominated system of the 1980s, and the 1990s when there was a shift towards greater sardine abundance, are explained by the mutual trophic replacement abilities of anchovy and sardine. Differences between the proposed indicators and mixed trophic impact assessment are highlighted, mainly resulting from the static versus dynamic nature of the models upon which they are based. Trophic indicators such as those presented here, together with other kinds of ecosystem indicators, may assist in defining operational frameworks for ecosystem-based fisheries management. 相似文献
5.
An ecosystem model representing the continental shelf of the East China Sea was fitted to a time series of data available from 1969 to 2000 using Ecopath with Ecosim. We used a process-oriented model to explore the extent to which changes in marine resources and the ecosystem were driven by trophic interactions and fishing activities. Fishing effort was used to drive the model, and observed catches were compared with the predicted catches in modeling. A reduction in the sum of the squared deviations of the observed and predicted catches was used as a metric for calibrating and assessing the goodness-of-fit of the model. Trophodynamic indicators were used to explore the ecosystem’s structural and functional changes from 1969 to 2000. The model’s predictions were consistent with observed catches for most functional groups. Trophodynamic indicators suggest a degradation pattern over time: both the mean trophic level of community and a modified version of Kempton’s index of biodiversity decreased over the time, while the total flow to detritus and the loss of production due to fishing increased from 1969 to 2000. Additionally, the ratio of demersal/pelagic abundances decreased as a result of an overall decrease in the abundance of demersal species and increase in pelagic fish in the ecosystem. 相似文献
6.
As China’s second-largest large marine ecosystem, the East China Sea Shelf has suffered from overfishing, eutrophication,
and physical disturbance over the last several decades. A trophic mass-balance model of this ecosystem was developed in order
to characterize the structure and functioning of its food web, to identify its keystone species, and to quantify the ecological
impacts of fishing that it sustained during the early 2000s. Using a multivariate statistical analysis, we identified 38 functional
groups for the trophic model, including fish and invertebrate groups targeted and not targeted by fisheries. Pelagic sharks
and rays were identified as the keystone species in the ecosystem. Strong benthic–pelagic coupling was indicated in this ecosystem.
In particular, this study highlighted the interdependent relationships that exist among plankton, benthic invertebrates, and
detritus. Recent fishing activities were characterized by high exploitation rates for various commercially targeted and non-targeted
species, leading to the removal of much of the ecosystem’s fishable production. Overall, our findings give a preliminary explanation
of the current problems of eutrophication and fishery depletion and other changes in the East China Sea Shelf, and highlight
the need for developing ecosystem-based fisheries management. 相似文献
7.
北部湾生态通道模型的构建 总被引:13,自引:0,他引:13
根据1997年~1999年在北部湾进行的渔业资源和生态环境调查数据,利用EwE软件构建北部湾生态系统的营养通道模型,模型由16个功能组构成,包括了哺乳动物和海鸟,每一组都代表在生态系统中具有相似地位的有机体,基本覆盖了北部湾生态系统能量流动的主要过程.模型分析表明,北部湾生态系统的能量流动主要以捕食食物链途径为主,其中无脊椎动物在能量从低级向高层次转换中起关键作用.各功能组的营养级范围为1.00~4.04,哺乳动物占据了最高营养层.生态网络分析表明,系统的能量流动主要有6级,来自初级生产者的能流效率为12.2%,来自碎屑的转换效率为12.3%,平均能量转换效率为12.2%.模型估算的可利用的生物量密度为8.7 t·km-2,生态系统的生物生产量只占系统净初级生产力的1.81%.当前北部湾海洋生态系统处于不稳定状态. 相似文献
8.
Timi JT Rossin MA Alarcos AJ Braicovich PE Cantatore DM Lanfranchi AL 《International journal for parasitology》2011,41(3-4):309-316
Whereas the effect of parasites on food webs is increasingly recognised and has been extensively measured and modelled, the effect of food webs on the structure of parasite assemblages has not been quantified in a similar way. Here, we apply the concept of decay in community similarity with increasing distance, previously used for parasites in geographical, phylogenetic and ontogenetic contexts, to differences in the trophic level (TL) based on diet composition of fishes. It is proposed as an accurate quantitative method to measure rates of assemblage change as a function of host feeding habits and is applied, to our knowledge for the first time, across host species in marine waters. We focused on a suite of 15 species of trophically-transmitted and non-specific larval helminths across 16 fish species (1783 specimens, six orders, 14 families) with different sizes and TLs, gathered from the same ecosystem. Not all host species harboured the same number and types of parasites, reflecting the differences in their ecological characteristics. Using differences in TL and body length as measurements of size and trophic distances, we found that similarity at both infracommunity and component community levels showed a very clear decay pattern, based on parasite abundance and relative abundance, with increasing distance in TL, but was not related to changes in fish size, with TL thus emerging as the main explanatory factor for similarity of parasite assemblages. Furthermore, the relationships between host TL and assemblage similarity allowed identification of fishes for which the TL was under- or over-estimated and prediction of the TL of host species based on parasite data alone. 相似文献
9.
Using an Ecosystem Modeling Approach to Explore Possible Ecosystem Impacts of Fishing in the Beibu Gulf,Northern South China Sea 总被引:2,自引:0,他引:2
Using the Ecopath with Ecosim software, a trophic structure model of the Beibu Gulf was constructed to explore the energy
flows and provide a snapshot of the ecosystem operations. Input data were mainly from the trawl survey data collected from
October 1998 to September 1999 and related literatures. The impacts of various fishing pressure on the biomass were examined
by simulation at different fishing mortality rates. The model consists of 20 functional groups (boxes), each representing
organisms with a similar role in the food web, and only covers the major trophic flows in the Beibu Gulf ecosystem. It was
found that the food web of the Beibu Gulf was dominated by the primary producers path, and phytoplankton was the primary producer
mostly used as a food source. The fractional trophic levels ranged from 1.0 to 4.02, and the marine mammals occupied the highest
trophic level. Using network analysis, the ecosystem network was mapped into a linear food chain, and six discrete trophic
levels were found with a mean transfer efficiency of 11.2%. The Finn cycling index was 9.73%. The path length was 1.821. The
omnivory index was 0.197. The ecosystem had some degree of instability due to exploitation and other human activities, according
to Odum’s theory of ecosystem development. A 10-year simulation was performed for each fishery scenario. The fishing mortality
rate was found to have a strong impact on the biomass. By keeping the fishing mortality rate at the current level for all
fishing sectors, scenario 1 had a drastic decrease in the large fish groups. The biomass of the small and medium pelagic fish
would increase to some extent. The biomass of the small and low trophic level species, jellyfish, prawns and benthic crustaceans
would be stable. The total biomass of the fishery resources would have a 10% decrease from the current biomass after 10 years.
In contrast, the reduced fishing mortality rate induced the recovery of biomass (scenarios 2–4). In scenario 2, the biomass
of the large demersal fish and the large pelagic fish would increase to over 16 times and 10 times, respectively, of their
current level. In scenario 4, the biomass of the large pelagic fish would increase to over 3 times of its current level. The
total biomass of the fish groups, especially the high trophic level groups, would become significantly higher after 10 years,
which illustrates the contribution on biomass recovery by relaxing the fishing pressure.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Author contributions: Xiaoping Jia designed research; Zuozhi Chen and Yongsong Qiu performed research; Zuozhi Chen, Yongsong Qiu, and Shannan
Xu analyzed data; and Zuozhi Chen and Shannan Xu wrote the article. 相似文献
10.
Sébastien Descamps Jon Aars Eva Fuglei Kit M. Kovacs Christian Lydersen Olga Pavlova Åshild Ø. Pedersen Virve Ravolainen Hallvard Strøm 《Global Change Biology》2017,23(2):490-502
The Arctic is warming more rapidly than other region on the planet, and the northern Barents Sea, including the Svalbard Archipelago, is experiencing the fastest temperature increases within the circumpolar Arctic, along with the highest rate of sea ice loss. These physical changes are affecting a broad array of resident Arctic organisms as well as some migrants that occupy the region seasonally. Herein, evidence of climate change impacts on terrestrial and marine wildlife in Svalbard is reviewed, with a focus on bird and mammal species. In the terrestrial ecosystem, increased winter air temperatures and concomitant increases in the frequency of ‘rain‐on‐snow’ events are one of the most important facets of climate change with respect to impacts on flora and fauna. Winter rain creates ice that blocks access to food for herbivores and synchronizes the population dynamics of the herbivore–predator guild. In the marine ecosystem, increases in sea temperature and reductions in sea ice are influencing the entire food web. These changes are affecting the foraging and breeding ecology of most marine birds and mammals and are associated with an increase in abundance of several temperate fish, seabird and marine mammal species. Our review indicates that even though a few species are benefiting from a warming climate, most Arctic endemic species in Svalbard are experiencing negative consequences induced by the warming environment. Our review emphasizes the tight relationships between the marine and terrestrial ecosystems in this High Arctic archipelago. Detecting changes in trophic relationships within and between these ecosystems requires long‐term (multidecadal) demographic, population‐ and ecosystem‐based monitoring, the results of which are necessary to set appropriate conservation priorities in relation to climate warming. 相似文献
11.
Joedison Rocha 《Ibis》2023,165(1):17-33
The loss of interactions and ecosystem functions is a concerning by-product of pervasive Anthropocene species decline and extinction. Ecological interactions between species sustain the provision of ecosystem processes, especially those mediated by trophic relationships such as pollination and predation. At the local habitat scale, the diversity of natural food sources may increase the diversity of interactions, thus enhancing the stability of local communities and ecosystem functioning. Here I discuss the importance of bromeliads as a potential provider of additional trophic interactions with birds, a key animal group in the Neotropics. Based on 88 studies published between 1965 and 2020 across the Neotropical region, I observed that bromeliads act as ‘wildlife restaurants’ by providing an additional food source throughout the year in almost all Neotropical ecosystems for at least 162 bird species (mostly hummingbirds). These plants (both epiphytic and terrestrial forms) can provide nectar, flowers, water for drinking, invertebrates, small vertebrates, seeds, and fruits, as well as nest materials and substrates. Given these trophic relationships between bromeliads and birds, actions to restore the richness and abundance of these plants in changed habitats would potentially enhance the local diversity of birds. I discuss and recommend the use of bromeliad transplantations as a relevant conservation tool for birds and some implications for the maintenance of species and interaction diversity in natural and agricultural habitats. 相似文献
12.
东太平洋中部中上层鲨鱼群落营养生态位分化 总被引:1,自引:0,他引:1
鲨鱼在大洋生态系统中占据着重要的生态地位,其作为顶级捕食者,通过下行效应直接影响生态系统的稳定.稳定同位素技术是目前研究摄食生态学强有力的手段之一,可利用碳氮稳定同位素在食物网中的特性分别指示鲨鱼的食物来源和营养级.本研究选取8种130尾采集自东太平洋中部的中上层鲨鱼,应用稳定同位素绘制其种群生态位图谱,比较不同种群间的生态地位及资源分配方式上的差异.结果表明:不同鲨鱼种群碳、氮稳定同位素比值存在显著差异;8种鲨鱼在东太平洋生态系统中的营养级为4.3~5.4,大青鲨、尖吻鲭鲨与其他6种鲨鱼存在摄食隔离,表现出独特的营养生态地位.这些结果充分证明大洋性中上层鲨鱼并非生态系统的冗余种,其营养生态位的独特性不会被其他捕食者简单地替代和弥补. 相似文献
13.
捕捞对北部湾海洋生态系统的影响 总被引:12,自引:0,他引:12
利用Ecopath with Ecosim (EwE) 5.1软件构建了北部湾海洋生态系统1959—1960年的Ecosim模型,包含渔业、海洋哺乳动物、海鸟、中上层鱼类、底层鱼类、底栖无脊椎动物等20个功能组,通过与1997—1999年调查数据对比,分析了捕捞活动对北部湾生态系统的结构和功能的影响.结果表明:近40年来在捕捞强度不断增加的压力下,生态系统的结构和功能发生显著变化,长寿命、高营养级的肉食性鱼类生物量下降明显,系统以短寿命、小型鱼类和无脊椎动物占优势.1999年的大中型鱼类的生物量仅为1960年的6%,而小型鱼类和无脊椎动物则明显上升,尤其是头足类生物量上升了2.7倍,渔获物的营养级则从1960年的3.2降低到1999年的298,体现了“捕捞降低海洋食物网”的特点,目前的开发模式是不可持续的.利用20世纪90年代数据预测了降低捕捞压力后生态系统的变化.本研究证实了可以使用Ecosim模型预测捕捞压力对生态系统的影响. 相似文献
14.
Hubert du Pontavice Didier Gascuel Gabriel Reygondeau Aurore Maureaud William W. L. Cheung 《Global Change Biology》2020,26(3):1306-1318
Sea water temperature affects all biological and ecological processes that ultimately impact ecosystem functioning. In this study, we examine the influence of temperature on global biomass transfers from marine secondary production to fish stocks. By combining fisheries catches in all coastal ocean areas and life‐history traits of exploited marine species, we provide global estimates of two trophic transfer parameters which determine biomass flows in coastal marine food web: the trophic transfer efficiency (TTE) and the biomass residence time (BRT) in the food web. We find that biomass transfers in tropical ecosystems are less efficient and faster than in areas with cooler waters. In contrast, biomass transfers through the food web became faster and more efficient between 1950 and 2010. Using simulated changes in sea water temperature from three Earth system models, we project that the mean TTE in coastal waters would decrease from 7.7% to 7.2% between 2010 and 2100 under the ‘no effective mitigation’ representative concentration pathway (RCP8.5), while BRT between trophic levels 2 and 4 is projected to decrease from 2.7 to 2.3 years on average. Beyond the global trends, we show that the TTEs and BRTs may vary substantially among ecosystem types and that the polar ecosystems may be the most impacted ecosystems. The detected and projected changes in mean TTE and BRT will undermine food web functioning. Our study provides quantitative understanding of temperature effects on trophodynamic of marine ecosystems under climate change. 相似文献
15.
Shane P. Griffiths Robert J. Olson George M. Watters 《Reviews in Fish Biology and Fisheries》2013,23(4):459-475
‘Wasp-waist’ control of marine ecosystems is driven by a combination of top-down and bottom-up forcing by a few abundant short-lived species occupying intermediate trophic levels that form a narrow ‘waist’ through which energy flow from low to high trophic levels is controlled. It has been assumed that wasp-waist control occurs primarily in highly productive and species-poor systems (e.g. upwelling regions). Two large, species-rich, pelagic ecosystems in the relatively oligotrophic eastern and western Pacific Ocean also show wasp-waist-like structure, in that short-lived and fast-growing cephalopods and fishes at intermediate trophic levels comprise the vast majority of the biomass. Possible forcing dynamics of these systems were examined using ecosystem models by altering the biomass of phytoplankton (bottom-up forcing), large pelagic predators (top-down forcing), and intermediate ‘wasp-waist’ functional groups independently and observing how these changes propagated throughout the ecosystem. The largest effects were seen when altering the biomass of mid trophic-level epipelagic and mesopelagic fishes, where dramatic trophic cascades occurred both upward and downward in the system. We conclude that the high productivity and standing biomass of animals at intermediate trophic levels has a strong top-down influence on the abundance of primary producers. Furthermore, their importance as prey for large predators results in bottom-up controls on populations at higher trophic levels. We show that these tropical pelagic ecosystems possess a complex structure whereby several waist groups and alternate trophic pathways from primary producers to apex predators can cause unpredictable effects when the biomasses of particular functional groups are altered. Such models highlight the possible structuring mechanisms in pelagic systems, which have implications for fisheries that exploit these wasp-waist groups, such as squid fisheries, as well as for fisheries of top predators such as tunas and billfishes that prey upon wasp-waist species. 相似文献
16.
Despite some fundamental differences in production processes and the ecology of consumer species on land and in the sea, further understanding of pattern and process in both biomes might be gained by applying common methods of macroecological analysis. We develop methods that reconcile apparent differences in abundance and occupancy for marine and terrestrial vertebrates, as exemplified by fish and birds. These recognize and take account of those aspects of the life history and ecology of marine and terrestrial animals that influence their abundance, distribution and trophic role. When abundance and occupancy are averaged within species over time we show that variation within a region is less for birds than fish, but when abundance and occupancy are averaged over space, the difference between birds and fish disappears. Further, we develop size rather than species‐structured abundance–occupancy relationships for fish assemblages and demonstrate that patterns of intra‐size class variation that are very similar to intraspecific variation in bird species, over both time and space. We argue that this result reflects the relative importance of body size and species identity respectively in determining trophic roles in marine and terrestrial environments. Selection of the appropriate analytical unit on land (species) and in the sea (size) helps to reconcile apparently divergent macroecological patterns, especially when these are driven by contrasting patterns of energy acquisition and use. 相似文献
17.
Knowing the trophic level of marine organisms is essential to understanding their ecological role in the ecosystem and for quantifying the ecosystem effects of fishing to establish effective management of fishing resources. In comparison to other systems, information about the trophic level of marine organisms in the Persian Gulf and Oman Sea is very scarce. Here, the main aim was to estimate trophic level in these areas using all available diet information from different marine species using TrophLab software. The trophic level of 32 fish species was estimated with the available diet data. The trophic level ranged from 2.28 to 4.50. High trophic levels were found for Chorocentrus nudus (TL = 4.7), Saurida tumbil (TL = 4.6), Rhizoprionodon acutus (TL = 4.5), Torpedo sinuspersici (TL=4.5), Gymnura poecilura (TL = 4.5), Sphyraena putnamae (TL = 4.5) and Euthynnus affinis (TL = 4.5). In contrast, lower trophic levels were estimated for Tenualosa ilisha (TL = 2.28) and Sardinella sindensis (TL = 2.92). As expected, a positive correlation was found between the trophic level and body size, indicating changes in the diet due to variations in predatory capacities. The results of this study may be useful in the formulation of trophic indicators and modelling of the ecosystems. 相似文献
18.
Malpelo Island is the largest marine protected area (MPA) in the Colombian Pacific; however, the lack of information regarding its ecological dynamics suggests that management and conservation strategies are developed from an individual approach (species or groups of species) and not from an ecosystem one. This study analyzes the terrestrial food web of Malpelo Island, Colombia, based on topological analysis (e.g., centrality). The food web was constructed from 27 nodes representing the main trophogroups, which consist of species or functional groups. Malpelo Island had a food web of four steps with a maximum separation among all trophogroups and trophic pathways, with two steps in average length. Furthermore, the food web was divided into three food web compartments, with a recurrence of connectivity patterns dominated by apparent and exploitative competition, followed by tri-trophic chains and omnivory. Five key trophogroups control the energy flow throughout the food web (detritus, the land crab Johngarthia malpilensis, the lizard Anolis agassizi, the Malpelo dotted galliwasp Diploglossus millepunctatus, and the Nazca booby Sula granti). The high importance of detritus suggests that bottom-up processes act as a control and regulation mechanism of trophic flows. The low number of food web compartments and a high recurrence of specific connectivity patterns in the Malpelo Island terrestrial ecosystem evidence different ecological processes centered on five trophogroups, allowing stability against disturbances. In addition, the simulation of trophogroup removal (randomly or directed) suggests that food web can be vulnerable to structural alterations in their properties, which may have consequences on the resilience of this ecosystem. This study contributes to the knowledge of the trophic dynamics of Malpelo Island, providing a potential tool for management and conservation measures from an ecosystemic approach. 相似文献
19.
DNA条形码及其在海洋浮游动物生态学研究中的应用 总被引:3,自引:1,他引:2
浮游动物的准确鉴定是浮游动物生态学研究的基础.传统的基于形态特征的鉴定不仅费时费力,而且部分类群特别是浮游幼体由于形态差异细微,鉴定存在困难,导致物种多样性被低估.DNA条形码(DNA barcodes)技术为浮游动物物种鉴定提供了一个有力工具,已迅速应用于海洋浮游动物生态学研究.本文介绍了DNA条形码的基本概念、优势及局限性,总结了该技术(主要是基于线粒体细胞色素C氧化酶第一亚基(mtCOI)基因序列片段的DNA条形码)在海洋浮游动物物种快速鉴定、隐种发现、营养关系研究、生物入侵种监测、群落历史演变反演、种群遗传学以及生物地理学中的成功应用.随着DNA条形码数据库信息量覆盖率的不断提高和新一代测序技术的快速发展,DNA条形码将提供除了种类鉴定外更加丰富的信息,从而帮助人们更好地理解海洋浮游动物的多样性及其在生态系统中的功能,推动海洋浮游动物生态学的发展. 相似文献
20.
Key ecosystem processes such as carbon and nutrient cycling could be deteriorating as a result of biodiversity loss. However, currently we lack the ability to predict the consequences of realistic species loss on ecosystem processes. The aim of this study was to test whether species contributions to community biomass can be used as surrogate measures of their contribution to ecosystem processes. These were gross community productivity in a salt marsh plant assemblage and an intertidal macroalgae assemblage; community clearance of microalgae in sessile suspension feeding invertebrate assemblage; and nutrient uptake in an intertidal macroalgae assemblage. We conducted a series of biodiversity manipulations that represented realistic species extinction sequences in each of the three contrasting assemblages. Species were removed in a subtractive fashion so that biomass was allowed to vary with each species removal, and key ecosystem processes were measured at each stage of community disassembly. The functional contribution of species was directly proportional to their contribution to community biomass in a 1:1 ratio, a relationship that was consistent across three contrasting marine ecosystems and three ecosystem processes. This suggests that the biomass contributed by a species to an assemblage can be used to approximately predict the proportional decline in an ecosystem process when that species is lost. Such predictions represent "worst case scenarios" because, over time, extinction resilient species can offset the loss of biomass associated with the extinction of competitors. We also modelled a "best case scenario" that accounts for compensatory responses by the extant species with the highest per capita contribution to ecosystem processes. These worst and best case scenarios could be used to predict the minimum and maximum species required to sustain threshold values of ecosystem processes in the future. 相似文献