Invasive Fauna Research Articles

Invasive Plant Species in Ghana: Route of Spread, Socio-Economic and Environmental Impact

Globally, there has been a rapid increase in biodiversity loss, these losses have been attributed to habitat loss and invasive flora and fauna species. Extensive work has been done on the losses brought about by invasive fauna species, however, the impact of invasive flora species has less been explored in Ghana. This review focused on the various alien plant species found in Ghana and the factors that support their spread, establishment, and colonization. Findings indicate that the common invasive plants in Ghana are Chromolaema odorata, Calopogonium mucunoides, Cedrella ordorata, Leucaena leucocephala, Broussonetia papyrifera and Prosopis glasdulosa, Azardiracta indica, Echinochloa colona, and Leucaena leucocephala. The economic losses and environmental impact of these plant species were also reviewed. This review revealed that there is an urgent need to initiate interventions to control the rapid spread of invasive plant species, those measures should be cost-effective and eco-friendly.

Tree recruitment after native frugivore extinction? A field experiment to test the impact of fruit flesh persistence in a tropical oceanic island

AbstractThe loss of large frugivores leads to seed dispersal loss and regeneration failure of numerous large-seeded trees near mother trees. Although Janzen–Connell effects are considered as the primary underlying cause, other factors remain understudied. Here, we used a field experiment to test the impact of flesh persistence on the recruitment of two large-seeded Sapotaceae species that lost their dispersers. In the rainforest of Mare Longue (Réunion), we sowed 3840 seeds in a four-factor design: seed treatment (seed cleaning; flesh persistence), canopy closure (understory; gap), year of sowing (01/2018; 11/2019) and species (Labourdonnaisia calophylloides, Mimusops balata). We also used camera traps to evaluate the impact of extant vertebrates. Seed treatment was by far the most influential factor: flesh persistence led to seedling recruitment divided by 3,2 on average, mainly due to failure of germination or seedling emergence. There were also significant variations in recruitment between species, years and canopy closure levels, notably due to the behaviour of the invasive fauna, especially giant snails that could unexpectedly restore recruitment by feeding on fruit flesh. Together, our results demonstrate strongly depleted recruitment due to flesh persistence and the importance of field experiments to understand the processes at work in complex ecosystems with novel plant–animal interactions.

Predicting the competitive interactions and trophic niche consequences of a globally invasive fish with threatened native species.

Novel trophic interactions between invasive and native species potentially increase levels of interspecific competition in the receiving environment. However, theory on the trophic impacts of invasive fauna on native competitors is ambiguous, as while increased interspecific competition can result in the species having constricted and diverged trophic niches, the species might instead increase their niche sizes, especially in omnivorous species. The competitive interactions between an omnivorous invasive fish, common carp Cyprinus carpio, and a tropically analogous native and threatened fish, crucian carp Carassius carassius, were tested using comparative functional responses (CFRs). A natural pond experiment then presented the species in allopatry and sympatry, determining the changes in their trophic (isotopic) niche sizes and positions over 4 years. These predictive approaches were complemented by assessing their trophic relationships in wild populations. Comparative functional responses revealed that compared to crucian carp, carp had a significantly higher maximum consumption rate. Coupled with a previous cohabitation growth study, these results predicted that competition between the species is asymmetric, with carp the superior competitor. The pond experiment used stable isotope metrics to quantify shifts in the trophic (isotopic) niche sizes of the fishes. In allopatry, the isotopic niches of the two species were similar sized and diverged. Conversely, in sympatry, carp isotopic niches were always considerably larger than those of crucian carp and were strongly partitioned. Sympatric crucian carp had larger isotopic niches than allopatric conspecifics, a likely response to asymmetric competition from carp. However, carp isotopic niches were also larger in sympatry than allopatry. In the wild populations, the carp isotopic niches were always larger than crucian carp niches, and were highly divergent. The superior competitive abilities of carp predicted in aquaria experiments were considered to be a process involved in sympatric crucian carp having larger isotopic niches than in allopatry. However, as sympatric carp also had larger niches than in allopatry, this suggests other ecological processes were also likely to be involved, such as those relating to fish prey resources. These results highlight the inherent complexity in determining how omnivorous invasive species integrate into food webs and alter their structure.

A case study of waterhyacinth (Eichhornia crassipes) control in Puerto Rico using glyphosate and hand removal

AbstractWaterhyacinth [Eichhornia crassipes (Mart.) Solm] is an aquatic invasive plant that is widespread in Puerto Rico, where it negatively effects estuaries, freshwater wetlands, potable water reservoirs, and wildlife refuges. Specifically, the tropical estuary San Juan Bay Estuary (SJBE) has been impacted with the presence of E. crassipes. Infestations have led to a reduction of water circulation in the system and have facilitated the establishment of invasive fauna. Therefore, a field study was conducted in a cove between Laguna San Jose and Peninsula Cantera to assess the use of glyphosate and hand removal as a management tool for E. crassipes control. Aquatic macroinvertebrates and water quality were also monitored as a measure of environmental impact due to management activities. Results indicated that at 2 wk after glyphosate application, E. crassipes biomass (dry weight) was significantly reduced to 0.27 kg DW m−2 at the treated plot compared with the nontreated plot, which yielded 0.62 kg DW m−2. Fresh weight of E. crassipes decreased more than 90% when hand removal was used compared with glyphosate treatment. Dissolved oxygen and water pH were not significantly different between sites; however, water salinity increased to 8 to 9 ppt at both plots as a result of tidal activity. The order Hemiptera followed by Sarcoptiformes were common in the aquatic macroinvertebrate community. Macroinvertebrate species found associated with E. crassipes and considered natural enemies were: Orthogalumna terebrantis Wallwork, Niphograpta albigutalis (Warren), and Neochetina eichhorniae Warner. The use of glyphosate to manage E. crassipes at the Laguna San Jose was useful as a short-term control method, and its efficacy may be enhanced over time with follow-up applications in combination with hand removal.

Evolution of the Cook Ice Cap (Kerguelen Islands) between the last centuries and 2100 ce based on cosmogenic dating and glacio-climatic modelling

AbstractThe Cook Ice Cap (CIC) on the sub-Antarctic Kerguelen Islands recently experienced extremely negative surface mass balance. Further deglaciation could have important impacts on endemic and invasive fauna and flora. To put this exceptional glacier evolution into a multi-centennial-scale context, we refined the evolution of the CIC over the last millennium, investigated the associated climate conditions and explored its potential evolution by 2100 ce. A glaciological model, constrained by cosmic ray exposure dating of moraines, historical documents and recent direct mass balance observations, was used to simulate the ice-cap extents during different phases of advance and retreat between the last millennium and 2100 ce. Cosmogenic dating suggests glacial advance around the early Little Ice Age (LIA), consistent with findings from other sub-Antarctic studies, and the rather cold and humid conditions brought about by the negative phase of the Southern Annular Mode (SAM). This study contributes to our currently limited understanding of palaeoclimate for the early LIA in the southern Indian Ocean. Glaciological modelling and observations confirm the recent decrease in CIC extent linked to the intensification of the SAM. Although affected by large uncertainties, future simulations suggest a complete disappearance of CIC by the end of the century.

Hydrological regimes in a tropical valley of New Caledonia (SW Pacific): Impacts of wildfires and invasive fauna

AbstractIn New Caledonia wildfires and invasive mammals (deer and wild pigs) constitute the major agents of land surface degradation. Our study reveals the linkage between land cover and water balance on the northeast coast of New Caledonia (2400 mm annual rainfall) located on a micaschist basement. The hydrological regime of characteristic and representative land surfaces is assessed using a 1‐year record from three 100 m2 plots each, located in a forest area degraded by an invasive fauna, in a woody savannah which is regularly burned, and in a healthy forest area. The three plots present highly contrasting hydrological regimes, with annual and maximum runoff/rain ratios during a rain event of, respectively, 0.82, 0.16, 0.03, and 2.7, 0.7, 0.2, for the degraded forest, the savannah and the healthy forest. Such results suggest that subsurface flow originating from the contributing area above the degraded forest plot should exfiltrate inside the plot. A conceptual model for the degraded forest plot shows that water exfiltrating inside the plot represents 61% of the observed runoff. In savannahs, water should mainly be transferred downstream by subsurface flow within a thick organic soil layer limited by an impervious clay layer at a 20–30 cm depth. Savannahs are generally located above forests and generate the transfer of rainwater to downslope forests. Exfiltration into the forests can be the result of this transfer and depends on the thickness and permeability of the forest topsoils and on topographic gradients. Water exfiltration in forest areas highly degraded by pigs and deer enhances erosion and increases further degradation. It probably also limits percolation in the areas located downstream by increasing the amount of superficial runoff concentrated in gullies.

Marine bioinvasions: bivalve molluscs introduced in northeast Brazil

ABSTRACT: Invasive alien species are those that, once introduced from other environments, adapt, starting to reproduce and proliferate in places they did not previously inhabit. The introduction of exotic marine species as a result of anthropic activity, whether intentionally or not, is a process that has been remote for centuries, which makes it difficult to assess the impact of these activities, making studies that address the status of knowledge about such organisms always important. Thus, this research aims to gather information about bivalve molluscs introduced into marine ecosystems in northeastern Brazil, in addition to discussing the knowledge of this invasive fauna for the Northeast, Southeast and South regions of Brazil. For that there was a search for bibliography in 5 databases - SciELO, Web of Science, Google Scholar, ScienceResearch.com and I3N Brazil Database of the Horus Institute for Environmental Conservation and Development. Three invasive bivalves for the northeastern region of Brazil were counted. When compared to the South and Southeast regions, the Northeast presents a significant amount of research on the ecology of the species Isognomon bicolor (C. B. Adams, 1845) and Mytilopsis leucophaeata (Conrad, 1831), which is very important, because with these results it is possible to track and understand the pathways that make bioinvasions possible. Regarding Perna Perna (Linnaeus, 1758), although there is a discussion about its supposed introduction in Brazilian waters, the species can be considered invasive in Northeastern Brazil.
 KEYWORDS: Invasive species, marine ecosystem, ecology.

RECORDS OF Sauromalus ater (DUMÉRIL, 1856) HATCHLINGS AND SUBADULTS ON SAN FRANCISCO ISLAND, GULF OF CALIFORNIA, MÉXICO

Six hatchlings of the Common or Sonoran Desert Chuckwalla (Sauromalus ater) ranging from 60 mm to 93 mm (SVL) as well as 10 subadult individuals (mostly ♀) ranging from 110 mm to 146 mm (SVL) were recorded during three casual walks on the small island San Francisco, Baja California Sur, Gulf of California, México, in January and February, 2019. The presence of these hatchlings and subadult females could be an important sign of chuckwallas’ recovery and of continued population’s recruitment following eradication of feral cats and goats from the island in 1999 and 2000 respectively, and despite the intense presence of humans (fishermen and tourists) on the island. The chuckwalla population seems to be growing and becoming conspicuous on San Francisco after almost two decades of rare and infrequent records of individuals. Also, the vegetation shows more abundance and diversity, and more extensive covering than in previous years. Other vertebrate species, like the Baja California Rattlesnake (Crotalus enyo) and the Burrowing Owl (Athene cunicularia) were recorded as well during the walks. All these observations possibly indicate a whole and progressive biota restoration on this tiny island after devastation by invasive fauna, combined with previous good wet years.

Predicting the ecological impacts of an alien invader: Experimental approaches reveal the trophic consequences of competition

Ecological theory on the trophic impacts of invasive fauna on native competitors is equivocal. Whilst increased interspecific competition can result in coexisting species having constricted and diverged trophic niches, the competing species might instead increase their niche sizes to maintain energy intakes. Empirical experiments can test invasion theory on competitive interactions and niche sizes across different spatial scales and complexity. The consequences of increased interspecific competition from a model alien fish Leuciscus idus were tested on two taxonomically and trophically similar native fishes, Squalius cephalus and Barbus barbus. Competitive interactions were tested in tank aquaria using comparative functional responses (CFRs) and cohabitation trials. The consequences of these competitive interactions for the trophic niche sizes and positions of the fishes were tested in pond mesocosms. Comparative functional responses revealed that compared to B.barbus, L.idus had significantly higher attack and consumption rates; cohabitation trials revealed B.barbus growth rates were depressed in sympatry with L.idus. For L.idus and S.cephalus, differences in their functional response parameters and growth rates were not significant. Pond mesocosms used stable isotope metrics to quantify shifts in the trophic niche sizes of the fishes between allopatry and sympatry using a substitutive experimental design. Isotopic niches were smaller and more divergent in sympatric paired species than predicted by their allopatric treatments, suggesting trophic impacts from interspecific competition. However, an all-species sympatric treatment revealed similar niche sizes with allopatry. This maintenance of niche sizes in the presence of all species potentially resulted from the buffering of direct competitive effects of the species pairs by indirect effects. Experimental predictions from tank aquaria assisted the interpretation of the constricted and diverged trophic niches detected in the paired-species sympatric treatments of the pond mesocosms. However, the all-species sympatric treatment of this experiment revealed greater complexity in the outcomes of the competitive interactions within and between the species. These results have important implications for understanding how alien species integrate into food webs and influence the trophic relationships between native species.

The role of anglers' perceptions and habits in biological invasions: perspectives from the Iberian Peninsula

Abstract Anglers are a recognized vector for invasive fauna, with both intentional and accidental introductions reported worldwide. The purpose of this study was to investigate the Iberian freshwater angler's habits and perceptions related to biological invasions, using an international and bilingual survey in Spain and Portugal. The results showed that anglers from both countries cover great distances to fish, and that they commonly visit several places and fish during consecutive days, representing a major risk for invasions. Yet, anglers' activity patterns throughout the year are not constant: the summer months involve more intense activity and, hence, entail higher risk. In both countries, the preferred fish species were invasive, and their introductions were reported more often than native species, with motivations being country‐dependent. The use of live bait was not frequent, but sometimes invasive species were used and the release of unused bait in the water was reported very frequently. Most anglers recognize that introductions have environmental impacts and that anglers have an active role in intentional introductions. However, only a minority is aware of the angler's role in accidental transportation of invasive species. These findings on anglers' behaviour patterns and perceptions may be used to model invasion risks and also improve monitoring and awareness programmes led by government agencies. Copyright © 2016 John Wiley & Sons, Ltd.

Live bait capture and crayfish trapping as potential vectors for freshwater invasive fauna

Fishing activities strongly contribute to biological invasions in freshwaters. The purpose of this study was to investigate the potential risks of live bait capture using dip nets and of crayfish trapping as vectors for invasive freshwater macrofauna dispersal. In the Tagus river basin (Portugal), where both activities are common, we evaluated the probability of capture and the electivity of the local aquatic macrofauna according to the method used. During the compulsory removal of the invasive species captured we also quantified fish desiccation survival capacities. We found, for both vectors, that the species exhibiting the highest probability of capture and the highest electivity were invasive, respectively, Gambusia holbrooki and Crangonyx pseudogracilis with the dip net, Procambarus clarkii and several invasive species with special relevance for Ameiurus melas with the crayfish trapping. Moreover, the desiccation survival capacities, of all invasive fishes analyzed, are compatible with long distance dispersal out of water, with special relevance to G. holbrooki . This study demonstrates that fishing activities contribute to long-distance dispersal of invasive fauna. Therefore, according to our findings, it is important to update the fishing regulation and simultaneously to raise fishermen awareness of this problem.

Biogeomorphic Impacts of Invasive Species

Invasive species, often recognized as ecosystem engineers, can dramatically alter geomorphic processes and landforms. Our review shows that the biogeomorphic impacts of invasive species are common, but variable in magnitude or severity, ranging from simple acceleration or deceleration of preexisting geomorphic processes to landscape metamorphosis. Primary effects of invasive flora are bioconstruction and bioprotection, whereas primary effects of invasive fauna are bioturbation, bioerosion, and bioconstruction. Land-water interfaces seem particularly vulnerable to biogeomorphic impacts of invasive species. Although not different from biogeomorphic impacts in general, invasive species are far more likely to lead to major geomorphic changes or landscape metamorphosis, which can have long-lasting impacts. In addition, invasive species can alter selection pressures in both macroevolution and microevolution by changing geomorphic processes. However, the differing timescales of biological invasions, landscape evolution, and biological evolution complicate assessment of the evolutionary impacts of invasive organisms.

Invasive mammals and habitat modification interact to generate unforeseen outcomes for indigenous fauna

Biotic invasions and habitat modification are two drivers of global change predicted to have detrimental impacts on the persistence of indigenous biota worldwide. Few studies have investigated how they operate synergistically to alter trophic interactions among indigenous and nonindigenous species in invaded ecosystems. We experimentally manipulated a suite of interacting invasive mammals, including top predators (cat Felis catus, ferret Mustela furo, stoat M. erminea), herbivores (rabbit Oryctolagus cuniculus, hare Lepus europaeus), and an insectivore (hedgehog Erinaceus europaeus occidentalis), and measured their effects on indigenous lizards and invertebrates and on an invasive mesopredator (house mouse Mus musculus). The work was carried out in a grassland/shrubland ecosystem that had been subjected to two types of habitat modification (widespread introduction of high-seed-producing pasture species, and areas of land use intensification by fertilization and livestock grazing). We also quantified food productivity for indigenous and invasive fauna by measuring pasture biomass, as well as seed and fruit production by grasses and shrubs. Indigenous fauna did not always increase following top-predator suppression: lizards increased on one of two sites; invertebrates did not increase on either site. Mesopredator release of mice was evident at the site where lizards did not increase, suggesting negative effects of mice on lizard populations. High mouse abundance occurred only on the predator-suppression site with regular production of pasture seed, indicating that this food resource was the main driver of mouse populations. Removal of herbivores increased pasture and seed production, which further enhanced ecological release of mice, particularly where pasture swards were overtopped by shrubs. An effect of landscape supplementation was also evident where nearby fertilized pastures boosted rabbit numbers and the associated top predators. Other studies have shown that both suppression of invasive predators and retiring land from grazing can benefit indigenous species, but our results suggest that the ensuing vegetation changes and complex interactions among invasive species can block recovery of indigenous fauna vulnerable to mesopredators. Top-down and bottom-up ecological release of mesopredators and landscape supplementation of top predators are key processes to consider when managing invaded communities in complex landscapes.

Biodiversity baseline survey of up country tea plantations in Nuwara Eliya District, Sri Lanka

Tea plantation is a prominent and very abundant land use type in the up country of Sri Lanka. Though they are disturbed habitats they still sustains a significant portion of up country biodiversity. Here we have studied the floral and faunal diversity of five selected tea estates in the Nuwara Eliya District, Sri Lanka. Though this type of studies has been carried out previously, most of them have only covered a few well known taxa. The present study has covered all vertebrate taxa excluding fishes, three main invertebrate taxa namely butterflies, odonates (dragonflies and damselflies) and land mollusks and higher plants widening the knowledge on biodiversity in up country tea plantations and providing baseline information for biodiversity conservation. Seven major habitat types were surveyed randomly in order to record flora and fauna. They are managed tea plantations, streams and ponds, wet marshy grasslands, fuel wood plantations, abandoned land, rock outcrops and anthropogenic habitats. Field work was carried out randomly from March 2011 to June 2012. Both day and night sampling was done and direct observations, indirect observations and reliable information from local people were used for the survey. Visual encounter survey method was the main sampling technique used during field surveys. Presence of 245 fauna and 158 flora species at the up country tea plantations in Nuwara Eliya district was confirmed during the study carried out. The vertebrates comprises of 22 amphibians, 19 reptiles, 95 birds and 21 mammals including 16, 10, 10 and 2 endemics respectively. The recorded bird fauna consists of 16 migrant species and 1 species known to have both migrant and resident population within the country. The invertebrates recorded from the study comprises of 43 butterflies, 18 land snails and 27 odonates. Respectively these invertebrate taxa consist of 2, 8 and 7 endemic species. A total of 28 vertebrates and 10 invertebrates are threatened species according to the 2007 Redlist of threatened fauna and flora in Sri Lanka. Endangered species such as the agamid lizards Calotes liocephalus and Ceratophora stoddartii, butterflies Udara lanka and Euthalia lubentina were found to be very rare within the study area as all of them were recorded on only one occasion during the study period. The 158 species of flora recorded from the study area comprised of 95 introduced species, 52 native species and 11 endemic species. From the introduced plants 46 were weeds and 17 were invasive plants. 5 of the recorded plant species are nationally threatened One of the main conservation issues observed at the study area was the spread of alien invasive species. Invasive fauna such as the mollusks Milax gagates, Allopeas gracile, Bradybaena similaris, Deroceras reticulatum and invasive flora such as Clidermia hirta, Eupatorium riparium and Ludwigia peruviana were commonly found in the surveyed areas. Other main conservation issues are use of chemical fertilizers and pesticides and soil erosion. Increase of organic farming practices and habitat enrichment programs may improve the biodiversity in these plantations. Aforestation of native plant species especially butterfly host plants and fruit trees, eradication of alien invasive species, establishment of reserved forest areas are some steps that can be followed in order to achieve this.

To catch a starling: testing the effectiveness of different trap and lure types

Context Worldwide, invasive fauna species present one of the most intractable problems for agriculture and natural systems. Our ability to improve control techniques to combat the global invasive species predicament is constrained within the bounds of both economic and ethical considerations. In south-eastern Australia, the common starling (Sturnus vulgaris) is an established invasive avian pest that is now making incursions into areas of Western Australia (WA) that are currently free of this species. The most cost-effective and widely implemented starling control tool is trapping with live-lure birds. In recent years, the use of live-lure birds has been questioned on both economic and ethical grounds, and consequently alternative lure methods need investigating. Aims To evaluate the effectiveness of different trap and lure combinations for the capture of starlings in western South Australia (SA). Methods Modified Australian Crow (MAC) traps, used traditionally in WA to trap starlings, and Myna traps, originally designed for trapping common mynas (Sturnus tristis), were set during the peaks in starling flocking activity (Austral summer, 2007) using three different lure types: (1) live lure (live starlings); (2) moving water; and (3) acoustic lures. A trapping grid consisting of a single Myna trap with live lure and three MAC traps, each with one type of lure (live, water or acoustic) was established at five sites on the Eyre Peninsula in SA and monitored twice daily for 28 days. Key results Live lures were significantly more effective at attracting starlings into traps compared with both water and sound lures. We also trapped at an additional three sites and showed that Myna traps caught ~1.5 times more starlings than MAC traps when both traps were fitted with live-lure birds. Conclusions Neither moving water nor acoustic play-back lures proved suitable replacements for the use of live-lure birds to capture starlings. The efficacy of alternative lure types may depend on several factors and may include neophobic response(s) to novel signals and also the length of time that an invasive population has been established. Implications We recommend that use of live lures is continued in ongoing starling control programs, and that MAC traps currently in use be modified to capitalise on known starling behaviour. Further research and development of traps that do not contain live lures will improve the welfare of invasive species control programs.

Trophic Ecology of Insular Cottonmouth Snakes: Review and Perspective

Florida cottonmouth snakes (Agkistrodon piscivorus conanti) inhabit insular as well as mainland habitat, and they occur in particularly large numbers on some of the Gulf coast islands of Florida. The success of this species on islands is attributable, in part, to a broad trophic niche that encompasses many prey items including carrion. Numerous cottonmouths living on the island of Seahorse Key consume primarily dead fish that are dropped from colonial nesting bird rookeries, but they also prey on rats (Rattus rattus) that are invasive fauna on the island. While alternative prey items (e.g. lizards) are available to newborn snakes, smaller individuals also scavenge for fish carrion at early ages. Field observations indicate there is social structure during foraging events that involve multiple snakes. Occasionally, insular cottonmouths scavenge for intertidal carrion and detritus that washes onto beaches. Numerous and diverse objects of appropriate size, shape, and odor are ingested by foraging snakes, including masses of marine algae that bear fish odors. The intensive scavenging behaviors of cottonmouths appear to reflect behavioral and physiological specializations that have evolved in response to insular resource limitations. Two important pathways by which allochthonous marine productivity enters the terrestrial food web to support these insular cottonmouths are (1) colonial bird rookeries and (2) shore drift of carrion and detritus. The importance of the bird rookeries as a source of marine fish is reflected in the observation that far lower numbers of cottonmouths occur on islands that lack a bird colony. We have no evidence that the insular cottonmouths feed on the colonial nesting birds, but they consume smaller passerine species.

The Ants of the Juan Fernández Islands: Genesis of an Invasive Fauna

A first study of the ants on the three main islands of the Juan Fernandez Archipelago (Chile) has revealed the presence of just three species, Hypoponera confinis, Linepithema humile, and Tetramorium bicarinatum, all widely distributed invasive species. Most notable among them is the Argentine ant, L. humile, an ecologically destructive species that has established several populations and appears to be expanding.

The status and implications of alien invasive species in Sri Lanka

Alien invasive species (AIS) is one among the various threats to the biodiversity of Sri Lanka. A survey was carried out to establish the present status of AIS in Sri Lanka. Wetland and terrestrial ecosystems of different climatic zones were surveyed randomly for the presence of AIS and their threats. Among the 59 AIS identified, 10 species of fauna and 13 species of flora are included in the list of 100 of the world's worst AIS. The alien invasive fauna of Sri Lanka includes 15 vertebrates and 5 invertebrates. The paper discusses the impact of alien invasive fauna and flora on the native species and stresses the need for a proper management strategy.

Cubitermes subarquatus termitaries as shelters for soil fauna in African rainforests

Most soil fauna in tropical rainforests require a pre-existing shelter for at least part of their life cycles. Among termites and ants, the most frequently encountered taxa, the availability of appropriate nesting sites is a major factor controlling the multiplication of colonies. Work carried out in five forests in southern Cameroon indicates that termitaries of Cubitermes subarquatus, whether active or abandoned, provide shelter for large numbers of invasive invertebrates, particularly ants and other termite species, and may be a determining factor in the patchy distribution of many taxa. Dissections of 90 termitaries (65 active, 25 abandoned) produced a great diversity of invasive fauna, including 354 ant colonies representing 75 species in 31 genera. Ants occurred in all abandoned termitaries but 6·1% of active termitaries had no ants present. Nevertheless, in total active termitaries sheltered more ant colonies (273) than did abandoned ones (81). Every termitary examined also sheltered founding pairs or incipient colonies of alien termites, but active C. subarquatus termitaries yielded fewer mature colonies of alien termites (56·9%) than did abandoned ones (84%).