Effects of invasive Pacific red lionfish Pterois volitans versus a native predator on Bahamian coral-reef fish communities

The recent irruption of Pacific red lionfish (Pterois volitans) on Caribbean and Atlantic coral reefs could prove to be one of the most damaging marine invasions to date. Invasive lionfish are reaching densities much higher than those reported from their native range, and they have a strong negative effect on the recruitment and abundance of a broad diversity of native coral-reef fishes. Otherwise, little is known about how lionfish affect native coral-reef communities, especially compared to ecologically similar native predators. A controlled field experiment conducted on small patch-reefs in the Bahamas over an 8-week-period demonstrated that (1) lionfish caused a reduction in the abundance of small native coral-reef fishes that was 2.5?±?0.5 times (mean?±?SEM) greater than that caused by a similarly sized native piscivore, the coney grouper Cephalopholis fulva (93.7 vs. 36.3?% reduction); (2) lionfish caused a reduction in the species richness of small coral-reef fishes (loss of 4.6?±?1.6 species), whereas the native piscivore did not have a significant effect on prey richness; (3) the greatest effects on the reef-fish community, in terms of both abundance and richness, occurred when both native and invasive predators were present; and (4) lionfish grew significantly faster (>6 times) than the native predator under the same field conditions. These results suggest that invasive lionfish have stronger ecological effects than similarly sized native piscivores, and may pose a substantial threat to native coral-reef fish communities.     

Indo-Pacific lionfish are larger and more abundant on invaded reefs: a comparison of Kenyan and Bahamian lionfish populations

The invasion by Indo-Pacific lionfish (Pterois volitans and P. miles) of the western Atlantic, Caribbean and Gulf of Mexico is emerging as a major threat to coral reef communities across the region. Comparing native and introduced populations of invasive species can reveal shifts in ecology and behaviour that can accompany successful invasions. Using standardized field surveys replicated at multiple sites in Kenya and the Bahamas, we present the first direct comparisons of lionfish density, body size, biomass and behaviour between native and invaded coral reefs. We found that lionfish occur at higher densities with larger body sizes and total biomass on invaded Bahamian coral reefs than the ecologically equivalent species (P. miles) does on native Kenyan reefs. However, the combined average density of the five lionfish species (Pterois miles, P. antennata, P. radiata, Dendrochirus brachypterus and D. zebra) on Kenyan reefs was similar to the density of invasive lionfish in the Bahamas. Understanding the ecological processes that drive these differences can help inform the management and control of invasive lionfish.     

Invasive freshwater molluscs are consumed by native fishes in South America

The diet of seven fish species from the Río de la Plata was studied to evaluate their behaviour as predators on the invasive bivalves Corbicula fluminea and Limnoperna fortunei. It was concluded that the teleosts Pterodoras granulosus, Pimelodus maculatus, Paraloricaria vetula and Ricola macrops prey upon C. fluminea, whilst Leporinus obtusidens, Rhinodoras dorbignyi and Brochiloricaria chauliodon feed on Lim. fortunei. These fish species had altered their diets to consume large amounts of these molluscs. Three of the fishes recorded here were previously unknown to feed on molluscs. The fishes studied here prey upon molluscs that ingest trace metals with their food items, thus monitoring the situation is suggested as several of these fish species are caught for human consumption.     

Invasive species of crayfish use a broader range of predation-risk cues than native species

The responses of invasive and native species of crayfish to conspecific and heterospecific alarm odors were recorded in the laboratory. Individuals of the North American invasive Procambarus clarkii responded just as strongly to odors from crushed Austropotomobius pallipes as they did to crushed conspecifics. The North American invasive Orconectes limosus also responded as strongly to P. clarkii odor as to conspecific odor. The native Italian species A. pallipes responded more strongly to conspecific alarm than to heterospecific alarm from P. clarkii. The pattern of invasive species of crayfish using a broader range of danger signals than displaced native species appears to be robust.     

Fluorescent epibiotic microbial community on the carapace of a Bahamian ostracod

Ostracods collected from shallow coral reefs in the Bahamas were found to exhibit blue light-stimulated orange fluorescence at night. Fluorescent spectra revealed the presence of orange fluorescence with a maximum emission at ~595 nm on the carapace of these ostracods, while scanning electron microscopy revealed a morphologically diverse microbial community covering the entire carapace of these ostracods. Pyrosequencing and cyanobacterial-specific 16S rRNA sequencing reveals that this epibiont community is highly diverse and highly variable between individual ostracods. Many species of Cyanobacteria in the orders Oscillatoriales and Chroococcales, as well as other Proteobacteria and diatom chloroplast sequences, were identified using the cyanobacterial-specific primers. While no fluorescent proteins or phycoerythrin were detected in these ostracods, it is possible that the observed orange fluorescence is the result of carotenoid fluorescence from Cyanobacteria. The microbial consortium forms an epibiotic biofilm on the carapace of these ostracods whose functions are unknown.     

Invasive Eupatorium adenophorum suffers lower enemy impact on carbon assimilation than native congeners

Enemy release hypothesis predicts that alien plants that escape from their natural enemies suffer lower enemy regulation in their introduced ranges than in native ranges. An extension of this theory suggests that if enemy release plays a crucial role in invasive success, then in the introduced range, invasive plants should also suffer lower local enemy impact than native residents (local enemy release hypothesis, LERH). In order to test LERH, we compared invasive Eupatorium adenophorum with two native congeners (E. heterophyllum and E. japonicum) in terms of damage by leaf enemies at two natural field sites and two manipulated sites. We also determined enemy impact on carbon assimilation at two manipulated sites. In each site, E. adenophorum was only damaged by herbivores, while in native congeners, leaf scabs or (and) leaf rolls was found in addition to herbivory damage. In both manipulated sites, the total enemy impact on carbon assimilation was lower for E. adenophorum than for native congeners; this observation was consistent with LERH. The results of this study indicate that a short co-existence time with generalist enemies (behavior constraint) might be the main contributor to the lower enemy impact on E. adenophorum.     

Invasive house geckos are more willing to use artificial lights than are native geckos

There is increasing concern about the ecological effects of light pollution, as artificial lighting spreads with urban expansion. While artificial lighting can negatively affect some species, others use it in novel ways. In tropical and subtropical regions, artificial lighting has created a novel niche: the ‘night light’ niche. Geckos living as human commensals (house geckos) are apparently well adapted to occupy this niche. In an urban area in north‐eastern Australia, we found that the invasive Asian house gecko Hemidactylus frenatus (Gekkonidae) occupies a broader range of light environments in the field than does the native gecko Gehyra dubia (Gekkonidae). Experimental removal of the invasive species from a building indicated that it did not behaviourally influence the light environments chosen by the native species in the short term; they continued to use darker areas even after the invasive species was removed. In Y‐maze experiments, neither species showed a significant preference for light or dark areas; however, preliminary data suggest the invasive species was more willing to explore the Y‐maze than the native species. The willingness of H. frenatus to forage closer to lights, where insect abundance is typically higher, might account for its success as a global invader of human environments, even in areas where other gecko species are established.     

Fungal community demonstrates stronger dispersal limitation and less network connectivity than bacterial community in sediments along a large river

Despite the essential functions of sedimentary bacterial and fungal communities in biogeochemical cycling, little is known about their biogeographic patterns and driving processes in large rivers. Here we investigated the biogeographic assemblies and co-occurrence patterns of sedimentary bacterial and fungal communities in the Jinsha River, one of the largest rivers in southwestern China. The mainstream of river was divided into upstream, midstream and downstream. The results showed that both bacterial and fungal communities differed significantly among three sections. For both communities, their composition variations in all sites or each river section were controlled by the combination of dispersal limitation and environmental selection, and dispersal limitation was the dominant factor. Compared with bacteria, fungi had stronger dispersal limitation. Co-occurrence network analyses revealed higher network connectivity but a lower proportion of positive interaction in the bacterial than fungal network at all sites. In particular, the keystone species belonging to bacterial phyla Proteobacteria and Firmicutes and fungal phyla Ascomycota and Chytridiomycota may play critical roles in maintaining community function. Together, these observations indicate that fungi have a stronger dispersal limitation influence and less network connectivity than bacteria, implying different community assembly mechanisms and ecological functions between bacteria and fungi in large rivers.     

Invasive California poppies (Eschscholzia californica Cham.) grow larger than native individuals under reduced competition

Invasive plants can be larger and more fecund in their invasive range than in their native range, although it is unknown how often this is a result of a genetically controlled shift in traits, a plastic response to a favourable environment, or a combination thereof. Here we present data from common garden experiments that compare the size and fecundity of native and invasive California poppies, Eschscholzia californica Cham. Individuals from 20 populations, half from California (native) and half from Chile (invasive), were grown both with and without competition from other plants in a container experiment and at two field locations. There were no differences in survival between native and invasive plants at any location. We found significant increases in size and fecundity in invasive populations at two of three locations when poppies were grown without competition from other plants. Our results indicate that genetic shifts in traits have occurred in invasive populations, and that the invasive plants are better at maximizing growth and reproduction in open environments.     

不同水稻组织内生细菌的群落多样性

[目的]为详细了解水稻不同组织内生细菌群落多样性。[方法]对宁粳43号内生细菌的总DNA提取后,采用高通量测序技术对水稻内生细菌的16S rRNA基因进行了序列测定,分析了水稻不同组织部位内生细菌群落结构特征。[结果]叶部共获得内生细菌OTUs 610个,茎部411个,根部174个。物种分类显示,叶部内生细菌种类隶属于22门40纲103目198科399属,其中优势类群是红球菌属（Rhodococcus）和乳酸杆菌属（Lactobacillus）,它们的相对丰度分别为21.00%和9.19%;茎部内生细菌种类隶属于19门31纲85目169科306属,其中优势类群是红球菌属和罗尔斯通菌属（Ralstonia）,它们的相对丰度分别为19.25%和13.52%;根部内生细菌种类隶属于9门19纲44目82科140属,其中优势类群是肠杆菌属（Enterobacter）和埃希氏杆菌属（Escherichia）,它们的相对丰度分别为81.13%和10.89%。根茎叶中相同的OTU有78个,放线菌门（Actinobacteria）与大多数细菌具有相关性。根系内生细菌中具有调控各种代谢网络功能的物种丰度高于茎部和叶部。[结论]不同水稻组织内生细菌具有丰富的群落多样性,其中叶部的内生细菌物种最丰富,根系参与各种代谢调控的细菌丰度最高,各个组织部位的优势菌属各不相同,变形菌门是最重要的水稻内生细菌。     

Invasive ants disperse seeds farther than native ants,affecting the spatial pattern of seedling recruitment and survival

Oecologia - Mutualists can vary in the quantity and quality of service which they provide to their partners. Variation in seed disperser quality depends on seed-processing traits, dispersal...     

Invasive ants alter foraging and parental behaviors of a native bird

Introduced species can exert outsized impacts on native biota through both direct (predation) and indirect (competition) effects. Ants frequently become established in new areas after being transported by humans across traditional biological or geographical barriers, and a prime example of such establishment is the red imported fire ant (Solenopsis invicta). Introduced to North America in the 1930's, red imported fire ants are now firmly established throughout the southeastern United States. Although these invasive predators can dramatically impact native arthropods, their effect on vertebrates through resource competition is essentially unknown. Using a paired experimental design, we compared patterns of foraging and rates of provisioning for breeding eastern bluebirds (Sialia sialis) in unmanipulated (control) territories to those in adjacent (treated) territories where fire ants were experimentally reduced. Bluebirds inhabiting treated territories foraged nearer their nests and provisioned offspring more frequently than bluebirds inhabiting control territories with unmanipulated fire ant levels. Additionally, nestlings from treated territories were in better condition than those from control territories, though these differences were largely confined to early development. The elimination of significant differences in body condition towards the end of the nestling period suggests that bluebird parents in control territories were able to make up the food deficit caused by fire ants, potentially by working harder to adequately provision their offspring. The relationship between fire ant abundance and bluebird behavior hints at the complexity of ecological communities and suggests negative effects of invasive species are not limited to taxa with which they have direct contact.     

Invasive plants do not display greater phenotypic plasticity than their native or non‐invasive counterparts: a meta‐analysis

Phenotypic plasticity is commonly considered as a trait associated with invasiveness in alien plants because it may enhance the ability of plants to occupy a wide range of environments. Although the evidence of greater phenotypic plasticity in invasive plants is considerable, it is not yet conclusive. We used a meta‐analysis approach to evaluate whether invasive plant species show greater phenotypic plasticity than their native or non‐invasive counterparts. The outcome of such interspecific comparisons may be biased when phylogenetic relatedness is not taken into account. Consequently, species pairs belonged to the same genus, tribe or family. The meta‐analysis included 93 records from 35 studies reporting plastic responses to light, nutrients, water, CO₂, herbivory and support availability. Contrary to what is often assumed, overall, phenotypic plasticity was similar between invasive plants and native or non‐invasive closely related species. The same result was found when separate analyses were conducted for trait plasticity to nutrients, light and water availability. Thus, invasive plant species and their native or non‐invasive counterparts are equally capable of displaying functional responses to environmental heterogeneity. The colonization of a wide range of environments by invasive plants could be due to their capacity to undergo adaptive ecotypic differentiation rather than to their ability to display plastic responses. Alternatively, phenotypic plasticity might play a role in plant invasion, but only during the initial phases, when tolerance of the novel environment is essential for plant survival. Afterwards, once alien plants are identified as invaders, the magnitude of phenotypic plasticity might be reduced after selection of the optimum phenotypes in each habitat. The identification of plant traits that consistently predict invasiveness might be a futile task because different traits favor invasiveness in different environments. Approaches at the local scale, focusing on the ecology of specific invasive plants, could be more fruitful than global macro‐analyses.     

The food of a community of East African freshwater fishes

Quantitative data on the food of the fishes inhabiting Lake Mcllwaine, Rhodesia, show that the feeding of the dominant species in this community ( Clarias gariepinus (Burchell), Hydrocynus vittatus (Castelnau), Tilapia melanopleura Dumeril, Tilapia mossamhica Peters, Tilapia macrochir Boulenger, Labeo altivelis Peters, and Gnathonemus macrolepidotus (Peters)) covers a wide spectrum, and almost all elements of the potential food supply are utilized. Exceptions are noted, however, and the introduction of the Indian carp, Catla catla (Cuv. & Val.), is advocated in order to utilize the large blooms of phyto- and zooplankton. The oligochaete, Branchiura cf. sowerbyi , which forms over 50% of the benthic biomass is also not utilized as a source of fish food. However, no fish species is known to feed on oligochaetes to any large extent. Predation by the Tigerfish, Hydrocynus vittatus , is shown to have severe effects upon recruitment to the valuable Tilapia fishery, and the reduction of the abundance of H. vittatus by means of selective fishing techniques is advocated.     

The food of a community of East African freshwater fishes

Quantitative data on the food of the fishes inhabiting Lake Mcllwaine, Rhodesia, show that the feeding of the dominant species in this community ( Clarias gariepinus (Burchell), Hydrocynus vittatus (Castelnau), Tilapia melanopleura Dumeril, Tilapia mossamhica Peters, Tilapia macrochir Boulenger, Labeo altivelis Peters, and Gnathonemus macrolepidotus (Peters)) covers a wide spectrum, and almost all elements of the potential food supplyare utilized. Exceptions are noted, however, and the introduction of the Indian carp, Catla catla (Cuv. & Val.), is advocated in order to utilize the large blooms of phyto- and zooplankton. The oligochaete, Branchiura cf. sowerbyi , which forms over 50% of the benthic biomass is also not utilized as a source of fish food. However, no fish species is known tofeed on oligochaetes to any large extent. Predation by the Tigerfish, Hydrocynus vittatus , is shown to have severe effects upon recruitment to the valuable Tilapia fishery, and the reduction of the abundance of H. vittatus by means of selective fishing techniques is advocated.