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1.
Exotic plant invaders that form monocultures and exclude native plants are often the most detrimental to native diversity
and the hardest to eradicate. To generate a monoculture, the invader must garner more resources than resident natives and,
once established, persist despite high densities of conspecific neighbors. Coincident with expansion and long-term persistence,
successful invaders typically accumulate senesced material, but the role of this litter in mediating the invader’s ability
to establish and maintain monospecific dominance has rarely been investigated. We used stands of the common reed, Phragmites australis, a prolific wetland invader in North America, to explore the impact of litter on interspecific competition with the native
rush, Juncus gerardii, and intraspecific competition among live shoots. In 10 × 10 m areas positioned on Phragmites expansion fronts, we removed litter to isolate its effect from live Phragmites on light availability, aboveground biomass and community composition. Compared to adjacent, unmanipulated fronts, light availability nearly tripled and Juncus biomass increased >170% in litter removal areas after 4 months. Although the positive response of Juncus and native forbs was most pronounced on the leading edge of Phragmites stands, litter removal triggered a 271% increase in native plant biomass even in the interior of stands where Phragmites’ live stem density was highest. Litter treatment did not significantly affect Phragmites biomass, but more, shorter stems emerged in litter removals revealing Phragmites modifies stem phenotype in response to local litter and light conditions. These results suggest that litter plays a central
role in Phragmites’ invasion process, from initial establishment to subsequent monospecific dominance. Thus, prescribed litter removal may be
an effective strategy to enhance coexistence of native plant populations in wetlands where eradication of invasive monocultures
is not an ecologically or economically feasible option. 相似文献
2.
Eupatorium adenophorum is one of the more noxious invasive plants worldwide. However, the mechanisms underlying its invasiveness are still not well
elucidated. In this study, we compared the invader with its two native congeners (E. heterophyllum and E. japonicum) at four irradiances in terms of growth, biomass allocation, morphology, and photosynthesis. The higher light-saturated photosynthetic
rate (P
max) and total leaf area of the invader may contribute to its higher relative growth rate (RGR) and total biomass compared with
its native congeners. Total biomass and RGR increased significantly with the increase of P
max and total leaf area. The higher support organ mass fraction and the lower root mass fraction of the invader may also contribute
to its higher RGR and biomass through increasing carbon assimilation and reducing respiratory carbon loss, respectively. The
higher growth rate of the invader increased its total leaf area, ramet number, and crown area. These traits may help the invader
to form dense monoculture, outshading native plant species. However, consistently higher leaf area ratio, specific leaf area,
and leaf mass fraction were not found across irradiances for the invader compared with its native congeners. Higher plasticity
in response to irradiance was also not found for the invader. The invader retained advantages over the natives across irradiances,
while its performance decreased with lower irradiance. The results indicate that the invader may be one of the few super invaders.
Reducing irradiance may inhibit its invasions. 相似文献
3.
Restoration sites are vulnerable to plant invasions due to habitat and resource alteration. We conducted an invasive plant-removal
study at a wetland restoration in the North Carolina Piedmont, a site dominated by the non-native invasive, Microstegium vimineum. Paired plots (M. vimineum hand-weeded and unweeded) were established and maintained to monitor response of plant species richness and diversity. Plots
increased from 4 to 15 species m−2 after three growing seasons of M. vimineum removal and 90% of the newly establishing species were native. Weeding ceased in the fourth growing season and M. vimineum rapidly re-invaded. Formerly weeded plots increased to 59% (±11% SE) M. vimineum cover, 25 of 51 plant species disappeared from the plots, and species richness decreased to an average of <8 species m−2. Our results show that we can quickly establish an abundant, diverse community with invasive removal, but that persistent
effort is required to monitor and maintain the long-term viability of this community. 相似文献
4.
Katherine G. Rascher André Große-Stoltenberg Cristina Máguas João Augusto Alves Meira-Neto Christiane Werner 《Biological invasions》2011,13(5):1099-1113
Acacia spp. are among the most serious plant invaders worldwide, and Acacia longifolia specifically causes problems in Portugal. In this study, we evaluated the impacts of A. longifolia invasion on community structure, light climate, plant diversity and regeneration in pine forests and open stabilized dunes
in northern and southern Portugal. Having the growth form of a small tree or shrub, between 1 and 8 m tall, A. longifolia tended to dominate the middle stratum of forests and to share dominance in the upper stratum of open dunes. The presence
of A. longifolia was associated with a decreased canopy cover in the lower stratum of all studied habitats, and at some sites with a significantly
increased leaf area index and reduced light intensity in the understory. Species number and diversity were reduced in some
habitats by up to 50% in invaded compared to non-invaded areas. Furthermore, in forest habitats, A. longifolia seedlings were facilitated by proximity to an adult A. longifolia while the establishment and growth of native seedlings was negatively impacted. The replacement of drought tolerant native
species by the water spending invader, A. longifolia, may have serious implications for ecosystem functioning, especially during the prolonged drought periods predicted to occur
in Portugal in the future. 相似文献
5.
Emily S. J. Rauschert David A. Mortensen Ottar N. Bjørnstad Andrea N. Nord Nora Peskin 《Biological invasions》2010,12(3):563-579
Microstegium vimineum (Japanese stiltgrass) is a non-native weed whose rapid invasion threatens native diversity and regeneration in forests. Using
data from a 4 year experiment tracking new invasions in different habitats, we developed a spatial model of patch growth,
using maximum likelihood techniques to estimate dispersal and population growth parameters. The patches expanded surprisingly
slowly: in the final year, the majority of new seedlings were still within 1 m of the original patch. The influence of habitat
was not as strong as anticipated, although patches created in roadside and wet meadow habitats tended to expand more rapidly
and had greater reproductive ratios. The long-term projections of the patch growth model suggest much slower spread than has
typically been observed for M. vimineum. The small scale of natural dispersal suggests that human-mediated dispersal, likely influenced by forest road management,
is responsible for the rapid spread of this invasive species. 相似文献
6.
Greg Spyreas Brian W. Wilm Allen E. Plocher David M. Ketzner Jeffrey W. Matthews James L. Ellis Edward J. Heske 《Biological invasions》2010,12(5):1253-1267
Although they are typically assumed to be negative, the consequences of plant invasions for native diversity or biological integrity are seldom broadly quantified (i.e., for multiple taxa or across large regions). We investigated the impacts associated with invasion of wetlands by reed canary grass (Phalaris arundinacea L.; RCG) on plants and several animal groups. In a local study, we compared plants, arthropods, and small mammals on treatment plots with reduced RCG dominance to those on highly invaded plots. We also conducted a companion study, where we measured RCG dominance and plants, arthropods, and birds in 82 randomly selected wetlands across Illinois (USA) to determine if our experimental results were consistent in communities across the region. Plant diversity, floristic quality, and diversity and abundance of Homopteran insects decreased with RCG dominance in all instances. Richness and abundance of all other arthropods decreased with increasing RCG in the local study, but no trend was detected in communities statewide. No relationship between total abundance or richness of small mammals (local) or birds (statewide) with RCG was detected. However, voles and shrews were more abundant, and mice less abundant, in RCG-dominated plots. These results support the hypothesis that there are negative effects for multiple taxa from RCG invasion. Because negative effects observed in the local study either corroborated, or were neutral with respect to results from statewide surveys, they suggest that native biodiversity and biological integrity are being dampened across wide areas of this invader’s range. 相似文献
7.
The success of invasive species eradication depends on a variety of factors, including those that initially facilitated the invasion, as well as removal and post-removal protocols. Two factors that appear to influence invasion by, and eradication of, the Neotropical shrub Lantana camara (L.), in southern Indian deciduous forests, are rainfall and removal method. However, their role in influencing eradication success is yet to be quantified, and remains unclear. We conducted an experiment to clarify how rainfall (high vs. low) and removal method (cutting vs. uprooting Lantana) influence re-invasion by Lantana, and native plant recovery. Rainfall influenced both eradication effort and outcomes—drier forest had lower starting levels of invader biomass, requiring less initial eradication effort, as well as lower subsequent Lantana re-invasion (from seed and rootstock) whereas wetter forest typically had greater starting levels of invader biomass, requiring considerably greater initial eradication effort, and greater Lantana re-invasion. However, wetter forest also showed greater native tree and forb recovery. Therefore, the availability of funds, local environmental gradients, and restoration priorities should inform the selection of restoration sites. With regard to removal method, uprooting combined with weeding of germinating Lantana, particularly after the rainy season, minimized overall re-invasion. Therefore, uprooting, followed by regular weeding of germinating Lantana and secondary invaders, is crucial to long-term Lantana eradication success. 相似文献
8.
Resident diversity and resource enrichment are both recognized as potentially important determinants of community invasibility,
but the effects of these biotic and abiotic factors on invasions are often investigated separately, and little work has been
done to directly compare their relative effects or to examine their potential interactions. Here, we evaluate the individual
and interactive effects of resident diversity and resource enrichment on plant community resistance to invasion. We factorially
manipulated plant diversity and the enrichment of belowground (soil nitrogen) and aboveground (light) resources in low-fertility
grassland communities invaded by Lolium arundinaceum, the most abundant invasive grass in eastern North America. Soil nitrogen enrichment enhanced L. arundinaceum performance, but increased resident diversity dampened this effect of nitrogen enrichment. Increased light availability (via
clipping of aboveground vegetation) had a negligible effect on community invasibility. These results demonstrate that a community’s
susceptibility to invasion can be contingent upon the type of resource pulse and the diversity of resident species. In order
to assess the generality of these results, future studies that test the effects of resident diversity and resource enrichment
against a range of invasive species and in other environmental contexts (e.g., sites differing in soil fertility and light
regimes) are needed. Such studies may help to resolve conflicting interpretations of the diversity–invasibility relationship
and provide direction for management strategies. 相似文献
9.
Cláudia Santos Gai Paulo Teixeira Lacava Maria Carolina Quecine Marie-Christine Auriac João Roberto Spotti Lopes Welington Luiz Araújo Thomas Albert Miller João Lúcio Azevedo 《Journal of microbiology (Seoul, Korea)》2009,47(4):448-454
Methylobacterium mesophilicum, originally isolated as an endophytic bacterium from citrus plants, was genetically transformed to express green fluorescent
protein (GFP). The GFP-labeled strain of M. mesophilicum was inoculated into Catharanthus roseus (model plant) seedlings and further observed colonizing its xylem vessels. The transmission of this endophyte by Bucephalogonia xanthophis, one of the insect vectors that transmit Xylella fastidiosa subsp. pauca, was verified by insects feeding from fluids containing the GFP bacterium followed by transmission to plants and isolating
the endophyte from C. roseus plants. Forty-five days after inoculation, the plants exhibited endophytic colonization by M. mesophilicum, confirming this bacterium as a nonpathogenic, xylem-associated endophyte. Our data demonstrate that M. mesophilicum not only occupy the same niche of X. fastidiosa subsp. pauca inside plants but also may be transmitted by B. xanthophis. The transmission, colonization, and genetic manipulation of M. mesophilicum is a prerequisite to examining the potential use of symbiotic control to interrupt the transmission of X. fastidiosa subsp. pauca, the bacterial pathogen causing Citrus variegated chlorosis by insect vectors. 相似文献
10.
Arundo donax L. (Poaceae) is an aggressive invader in California’s riparian habitats. Field experiments were conducted to examine invader
and site attributes important in early invasion. One hundred A. donax rhizomes were planted along five transects into each of three southern California riparian habitats. Pre-planting rhizome
weight was recorded, along with site variables including percent bare ground, litter depth, PAR, soil moisture, soil temperature,
incidence of herbivory, native canopy cover, and plant community richness and diversity. A. donax shoot emergence, survival time, and shoot height were recorded for approximately 10 months. The experiment was repeated over
three years in different locations within each site. When years and sites were pooled to reveal large-scale patterns, A. donax performance was explained by rhizome weight, soil moisture, bare ground, soil temperature, and herbivory. When each site
was considered singly, A. donax was positively correlated with different variables in each location. Species richness was correlated with A. donax performance in only one site. Our results indicate that A. donax establishment in riparian habitats is promoted by both vegetative reproduction and favorable abiotic environmental factors
and relatively unaffected by the composition of the native community. The positive response of A. donax to disturbance (bare ground) and high resource availability (soil moisture), combined with a competitive perennial habit
suggest that this species takes advantage of a competitive-ruderal life history. The ability of A. donax to respond to different conditions in each site combined with low genetic and phenotypic variation seen in other studies
also suggests that a high degree of environmental tolerance contributes to invasion success. 相似文献
11.
The grass shrimp Palaemonetes pugio, a species common to Spartina alterniflora-dominated marshes, may be sensitive to the invasion of the common reed Phragmites australis in northeastern US salt marshes. We examined two questions: (1) Do grass shrimp have a preference for the native plant over the non-native plant? (2) Are grass shrimp more effective foragers on P. australis? We tested the first hypothesis by comparing the amount of time shrimp spend in physical contact with the plant types over a 1-h period. Shrimp were observed under different arrangements of vegetation to control for differences in conspicuous structural features. Additionally, the amount of time shrimp spent foraging on S. alterniflora and P. australis shoots was compared to determine if shrimp graze more often on S. alterniflora. Shrimp spent significantly more time in contact with S. alterniflora only when plant types were grouped at opposite ends of aquaria, but did not exhibit a foraging preference for this plant type. To address our second question, we investigated the effects of shrimp foraging on stem epifauna, an assemblage of semi-aquatic invertebrates associated with macrophyte shoots. Previous research showed that P. australis supports a lower density of stem-dwelling epifauna relative to S. alterniflora. We hypothesized that the primary grazer of this community, P. pugio, can forage on P. australis stems more effectively due to structural differences between the two plants, causing the lower abundance of epifauna through top-down effects. We exposed individual shoots inhabited by epifauna to shrimp and compared faunal densities on exposed shoots to densities on control shoots after 18 h. The reduction of epifauna by predation was proportional on the two plant types. Therefore, top-down effects can be ruled out as an explanation for the patchy distribution of epifauna observed in P. australis–S. alterniflora marshes. 相似文献
12.
13.
Jonathan T. Hovius Beatrix E. Beisner Kevin S. McCann Norman D. Yan 《Biological invasions》2007,9(3):233-243
As a recent invader of North American lakes, Bythotrephes longimanus has induced large changes in crustacean zooplankton communities through direct predation effects. Here we demonstrate that
Bythotrephes can also have indirect food web effects, specifically on rotifer fauna. In historical time series data, the densities of
the colonial rotifer Conochilus unicornis significantly increased after Bythotrephes invasion in Harp Lake, Ontario. No such changes were observed in a non-invaded reference lake, the nearby Red Chalk Lake.
Evidence for two mechanisms explaining the Conochilus increase was examined based on changes to the crustacean zooplankton community over time. Rapid and severe declines in several
herbivorous species of cladoceran zooplankton after Bythotrephes detection indicated a decrease in exploitative competition pressure on Conochilus. Secondly, a later and significant decline to virtual extinction of native invertebrate predators (Mesocyclops and Leptodora) could account for the observed Conochilus increase which also began 1–2 years after invasion by Bythotrephes. Ultimately, it appears that both reduced competition followed by a loss of native invertebrate predators were necessary
to lead to the large Conochilus densities observed following invader establishment. From this analysis of long-term community data, it appears that Bythotrephes has important indirect, as well as direct, food web effects in newly invaded North American lakes with implications for trophic
relationships. 相似文献
14.
An increasing number of recent studies indicate that multiple interacting factors can affect the invasion of plants. However,
few studies have focused on asexual propagation and the interaction of propagation with environmental factors that regulate
the invasive potential of introduced exotic species in aquatic habitats. This study was designed to investigate the differences
in asexual propagation between introduced exotic and non-invasive native aquatic macrophytes in nutrient-poor and nutrient-rich
sediments and to test the hypothesis that differences in asexual propagation (stem fragment production) and propagule establishment
between introduced exotic and non-invasive native macrophytes are driven by sediment nutrient levels. Three exotic aquatic
macrophytes (Elodea nuttallii, Myriophyllum aquaticum, and M. propinquum) recently introduced to China and their non-invasive native counterparts (Hydrilla
verticillata, M. oguraense, and M. ussuriense) were used for comparison in nutrient-poor (TN 0.59 and TP 0.03 mg g−1) and nutrient-rich (TN 2.35 and TP 0.10 mg g−1) sediments. After 8 weeks of growth, the exotic species tended to produce more total biomass, branch biomass and apical shoots
and have higher relative growth rate (RGR) than their native counterparts in nutrient-rich sediment. Rooting efficiency and
root growth of exotic fragments were higher than that of native counterparts in nutrient-rich sediment, although the survival
rates of fragments did not differ between native and exotic species. In addition, superior traits (rooting efficiency and
root growth) of exotic species were also observed in nutrient-poor sediment, but to a lesser degree than in nutrient-rich
sediment. These results suggest that asexual propagation of these three introduced exotic macrophytes is more effective in
nutrient-rich sediment than in nutrient-poor sediment in China. 相似文献
15.
Gregory P. Asner Roberta E. Martin David E. Knapp Ty Kennedy-Bowdoin 《Biological invasions》2010,12(3):477-494
The negative effects of biological invasion are often the focus of ecological studies, but few have considered potential positive
impacts, such as increased carbon storage, resulting from invasion. We combined airborne imaging spectrometer and LiDAR (light
detection and ranging) observations with field measurements to assess if the highly invasive nitrogen-fixing tree Morella faya alters canopy 3-D structure and aboveground biomass (AGB) along a 1,500 mm precipitation gradient in Hawaii. Airborne analysis
of canopy water content, leaf nitrogen concentration, fractional canopy cover, and vegetation height facilitated mapping of
native- and Morella-dominated canopies in rainforest, woodland–savanna and shrubland ecosystems, with Morella detection errors ranging from 0 to 13.4%. Allometric equations were developed to relate the combined LiDAR and spectral data
to field-based AGB estimates (r
2 = 0.97, P < 0.01), and to produce a map of biomass stocks throughout native and invaded ecosystems. The structure of the invasive Morella canopies varied by ecosystem type, and the invader shaded out native understory plants in rainforest zones. Despite a 350%
increase in AGB going from shrubland to rainforest, Morella did not increase average AGB in any ecosystem it invaded. Furthermore, spatial distributions of biomass indicated that Morella decreased maximum AGB in the woodland–savanna ecosystems. We conclude that Morella tree invasion does not enhance aboveground carbon stocks in any ecosystem it invades in Hawaii, thereby minimizing its contribution
to this potentially important ecosystem service. We also found that the fusion of spectral and LiDAR remote sensing provided
canopy chemical and structural data facilitating a landscape assessment of how biological invasion alters on carbon stocks
and other ecosystem properties. 相似文献
16.
Disturbances that intensify with agriculture and/or urban development are thought to promote the spread of invasive plants, such as the clonal perennial reed canary grass ( Phalaris arundinacea L). To test this relationship and interactions among disturbances, we subjected wet prairie assemblages within 1.1 m2 mesocosms to invasion by Phalaris and addition of nutrients, sediments, and flooding. Species richness decreased with the application of sediments and/or flooding of 4 consecutive weeks or longer. Losses of up to six dominant and subdominant species in these treatments increased light transmission through the plant canopy by as much as 400% over the control. Light availability in July and September was a strong predictor of end-of-season aboveground biomass of Phalaris. Phalaris was also 35% and 195% more productive when nutrients were added at low and high levels, respectively. Multiple factors in combination were usually additive in their effects on invasion, but sediments and nutrients interacted with flood regime to synergistically increase invasion in some cases. A separate experiment likewise revealed a synergistic interaction between added nutrients and simulated grazing. We suggest that multiple factors be mitigated simultaneously to reduce invasion of Phalaris. 相似文献
17.
Yong jun Zhao Hua Qing Cong jiao Zhao Chang fang Zhou Wen guang Zhang Yan Xiao Shu qing An 《Hydrobiologia》2010,637(1):143-155
Phenotypic plasticity of the two salt marsh grasses Spartina alterniflora and Phragmites australis in salt marshes is crucial to their invasive ability, but the importance of phenotypic plasticity, nitrogen levels, and intraspecific
competition to the success of the two species is unclear at present. Spartina alterniflora Loisel. is an extensively invasive species that has increased dramatically in distribution and abundance on the Chinese and
European coasts, and has had considerable ecological impacts in the regions where it has established. Meanwhile, Phragmites australis Cav., a native salt marsh species on the east coast of China, has replaced the native S. alterniflora in many marshes along the Atlantic Coast of the US. This study determined the effects of nitrogen availability and culm density
on the morphology, growth, and biomass allocation traits of Spartina alterniflora and Phragmites australis. A large number of morphological, growth, and biomass parameters were measured, and various derived values (culm: root ratio,
specific leaf area, etc.) were calculated, along with an index of phenotypic plasticity. Nitrogen addition significantly affected
growth performance and biomass allocation traits of Spartina alterniflora, and culm density significantly affected morphological characteristics in a negative way, especially for Spartina alterniflora. However, there were no significant interactions between nitrogen levels and culm density on the morphological parameters,
growth performances parameters, and biomass allocation parameters of the two species. Spartina alterniflora appears to respond more strongly to nitrogen than to culm density and this pattern of phenotypic plasticity appears to offer
an expedition for successful invasion and displacement of Phramites australias in China. The implication of this study is that, in response to the environmental changes that are increasing nitrogen levels,
the range of Spartina alterniflora is expected to continue to expand on the east coast of China. 相似文献
18.
Plant–soil interactions have been proposed as a causative mechanism explaining how invasive plant species impact ecosystem
processes. We evaluate whether an invasive plant influences plant and soil-microbe acquisition of nitrogen to elucidate the
mechanistic pathways by which invaders might alter N availability. Using a 15N tracer, we quantify differences in nitrogen uptake and allocation in communities with and without Microstegium vimineum, a shade-tolerant, C4 grass that is rapidly invading the understories of eastern US deciduous forests. We further investigate if plants or the
microbial biomass exhibit preferences for certain nitrogen forms (glycine, nitrate, and ammonium) to gain insight into nitrogen
partitioning in invaded communities. Understory native plants and M. vimineum took up similar amounts of added nitrogen but allocated it differently, with native plants allocating primarily to roots
and M. vimineum allocating most nitrogen to shoots. Plant nitrogen uptake was higher in invaded communities due primarily to the increase
in understory biomass when M. vimineum was present, but for the microbial biomass, nitrogen uptake did not vary with invasion status. This translated to a significant
reduction (P < 0.001) in the ratio of microbial biomass to plant biomass nitrogen uptake, which suggests that, although the demand for
nitrogen has intensified, microbes continue to be effective nitrogen competitors. The microbial biomass exhibited a strong
preference for ammonium over glycine and nitrate, regardless of invasion status. By comparison, native plants showed no nitrogen
preferences and M. vimineum preferred inorganic nitrogen species. We interpret our findings as evidence that invasion by M. vimineum leads to changes in the partitioning of nitrogen above and belowground in forest understories, and to decreases in the microbial
biomass, but it does not affect the outcome of plant–microbe–nitrogen interactions, possibly due to functional shifts in the
microbial community as a result of invasion. 相似文献
19.
MA Weaver CD Boyette RE Hoagland 《World journal of microbiology & biotechnology》2012,28(5):1941-1946
The fungal plant pathogen, Myrothecium verrucaria, is highly virulent to several important weed species and has potential utility as a bioherbicide. However the production
of macrocyclic trichothecene mycotoxins by this fungus presents significant safety concerns. It was discovered that trichothecenes
are removed from M. verrucaria spores by repeated washes with water. These washed spores retained bioherbicidal efficacy against kudzu when tested in field
trials and on sicklepod when tested under greenhouse conditions. Changes in the growth medium combined with washing spores
with water resulted in greater than 95% reduction in roridin A and verrucarin A. Washing spores reduced trichothecene concentrations
in spore preparations with no significant effect on plant biomass reduction, thus demonstrating the possibility of M. verrucaria formulations with improved safety to researchers, producers and applicators. 相似文献
20.
Diets of Mysis relicta from four lakes in central Ontario that had been invaded by Bythotrephes longimanus and three lakes that had not been invaded were investigated using gut content analysis and fatty acid (FA) composition. Gut
content analysis of M. relicta revealed a high incidence of cannibalism in all lakes, and consumption of B. longimanus and native zooplanktivorous midges in the genus Chaoborus in lakes where these were present. Cladocera other than B. longimanus were present in the guts of all M. relicta examined except those from Bernard Lake, the lake with the most B. longimanus. In that lake, B. longimanus was the most frequent diet item. Copepod remains were found in 60–100% of M. relicta guts with the lowest frequency occurring in Bernard Lake. Fatty acids (FA) that contributed strongly to the variation in
FA composition in M. relicta, as revealed by a principal component analysis, were C16:0 (palmitic acid), C16:1n7 (palmitoleic acid), C18:1n9c (oleic acid),
C20:4n6 (arachidonic acid), C20:5n3 (eicosapentaenoic acid), and C22:6n3 (docosahexaenoic acid). Significant differences in
FA amount and composition of M. relicta were found between invaded and non-invaded lakes, and among lakes within these groups. Generally, M. relicta in non-invaded lakes had higher concentrations of C16:0, C18:1n9c, C18:2n6c (linoleic acid), C18:3n3 (α-linolenic acid) and
C20:4n6, while M. relicta in invaded lakes had higher concentrations of C22:6n3. Two of the non-invaded lakes had lower water transparency, as measured
by Secchi depth, which may be the reason why mysids and abundant populations of Chaoborus spp. could be found in the water column during the day. However, differences in FA profiles and gut contents of M. relicta between invaded and non-invaded lakes are consistent with competition for Cladocera in the presence of the invader rather
than pre-existing differences among lakes. We conclude that the diet of M. relicta is affected by the invasion of B. longimanus. 相似文献