Invasive species thesis

Together, the three essays suggest greater emphasis on the use of science than interest-group lobbying for listing noxious weeds. Moreover, a better documentation of potential invaders, their characteristics and impacts on non-native environments, is important in controlling the introduction and spread of noxious weeds, and the consequent economic and ecological damages. Relationships Parents: This work has no parents. Min, He.

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Many non-native weed pests of food, fiber, and nursery crops pose threats to U. Doctor of Philosophy Ph. Agricultural and Resource Economics. Oregon State University. Gopinath, Munisamy. Agriculture and Resource Economics. Graduate School.

Ecologists: Time to End Invasive-Species Persecution

Copyright Not Evaluated. Theoretical, meta-analytical, and review papers were We found papers published in the leading invasion biology journals Biological Invasions and Diversity and Distributions in Terrestrial organisms received the most attention Theoretical and review papers represented 3. Our temporal analyses using selected journals in general ecology and in aquatic sciences indicated that aquatic scientists are paralleling the trend found in general ecology journals in regard to the interest in non-native species. Interestingly, all these surveys including ours show that there was a time lag between the influential book by Elton, in , and the growth of the invasion biology, which started in the mid s.

The increasing number of investigations in aquatic ecosystems is related mainly to species that have caused severe ecological and economic damages, such as common carp, brown trout, tilapia, and zebra mussels MacIsaac et al. Our review also showed that studies about freshwater and marine ecosystems and organisms are underrepresented in leading general journals of ecology as well as in leading journals of invasion biology. This over-representation of terrestrial, compared to aquatic organisms, has also been found in other large systematic literature reviews about invasions Jeschke et al.

For example, the number of articles on the biodiversity-ecosystem functioning research Caliman et al. Thus, it seems that ecologists should still allocate more efforts to comprehend the structure and functioning of aquatic ecosystems including the causes and consequences of AIS. At the same time, increasing scientific efforts on AIS would be also important to understand if there are differences in the mechanisms controlling invasions between the two realms, and if so to which extent they differ.

In summary, our literature survey suggests that the number of papers about AIS in aquatic scientific journals is growing at similar rates than those published in general ecology journals; however, the studies about AIS are underrepresented in leading journals of ecology and invasion biology.

We contended that the latter findings reflect a current view, since we relied only on articles produced in the year Even so, this analysis suggests that aquatic ecologists should devote more efforts to put their findings within a broader context and thus, contribute theoretical advances to the field of invasion biology.

‚Č°Essays on Invasive Species. Free Examples of Research Paper Topics, Titles GradesFixer

Main topics and organisms investigated in the 31 papers of this special issue of Hydrobiologia. Mechanisms that mediate invasion success and impacts caused by invasive species. Bivalvia Dreissena polymorpha and D.

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Macrophytes Myriophyllum spicatum and Potamogeton crispus. Macrophytes Alternanthera philoxeroides. Crustacea Orconectes rusticus and Gastropoda Cipangopaludina chinensis and Viviparus georgianus. Macrophytes Ludwigia grandiflora and Myriophyllum aquaticum. Crustacea Dikerogammarus villosus and Bivalvia Dreissena polymorpha. Fish Cyprinus carpio and Oreochromis aureus.

Amphibian Lithobates catesbeiana and fish Gambusia affinis. These articles also represent a variety of ecosystems and geographical regions. The studies presented here addressed rivers, lakes, ponds, floodplains, and streams, and both observational and experimental studies were conducted. Nine of the studies came from tropical and sub-tropical regions.


We summarize below the main findings of the papers published in this SI. The environmental factors and ecological mechanisms that mediate invasion, along with potential impacts caused by microorganisms especially bacteria , are discussed in a review by Amalfitano et al. Their article presents the main hypotheses in ecology and biological invasions that have been applied to microorganisms.

Amalfitano et al. The authors conclude that changes made by humans including pollution may reduce the resistance of natural communities to invasion, and that invasions by microorganisms could cause important effects on the ecosystem functioning. Three other review articles focused on exotic invasive macrophytes. The role of competition for macrophyte success received support in several examples, and allelopathics novel weapon hypothesis seem to play an important role in invasion success of macrophytes. Two other mechanisms that explain invasion potential of macrophytes were propagule pressure and fluctuation in resources.

The authors also state that functional diversity and phylogenetic diversity, along with redundancy and species diversity, could help predict invasion success and they suggest potential areas for future research with macrophytes. Thomaz et al.


Propagule pressure explains cases of successful invasion in these ecosystems, and factors related to disturbance, resource availability, and biotic resistance indicate that invasibility of these aquatic ecosystems parallels terrestrial ones. The invasion paradox was also found for non-native macrophytes in some tropical aquatic ecosystems.

Impacts were identified at the water medium, in populations and communities of several trophic levels, and they are harsher when macrophytes behave as ecosystem engineers. According to Thomaz et al. Combining different scientific paradigms e. Brundu reviewed the literature about the introduction pathways, distribution, and main impacts of the invasive macrophyte species in the European and Mediterranean Plant Protection Organization Zone.

The means of introduction have been mainly related to horticultural, ornamental gardens, and aquaria activities, although research and phytoremediation have also contributed to introductions of macrophytes. A list of 21 species of alien macrophytes, along with potential ecological and socio-economic impacts of them in the Mediterranean region, is also provided by Brundu He suggests prevention, together with management including habitat restoration as strategies to avoid threats by these plants.

Their survey suggests that this bivalve stimulates growth of periphyton and macrophytes, by changing nutrient concentrations and reducing organic particles in water, and favors the dominance by cyanobacteria. However, L. The spread, dynamics, and impacts caused by the bivalves Dreissena polymorpha zebra mussel and D. The number of water bodies invaded by zebra mussels in the US far exceeds the ones invaded by quagga mussels. Zebra mussels combine rapid colonization of new areas with rapid population increase to damaging levels, giving them the potential to more rapidly impact ecosystems than do quagga mussels.

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Nevertheless, the overall effects of dreissenids are complex. The impacts of each invasive mussel depend on the lake morphometry and water mixing rates. The diversity and abundance of native invertebrates increase in response to habitat and food provided by these invasive species in the littoral zone, but competition of quagga mussel for space and food reduces native diversity and abundance of macroinvertebrates in the profundal zone Karatayev et al.

Two studies about invasion vectors investigated the effects of desiccation on survival of macrophyte propagules, simulating the effects of recreational boat movement on macrophyte invasions. Typical boaters in this region visit multiple lakes within a couple of days, suggesting that these common weeds can be readily transported and colonize new ecosystems. Furthermore, vegetative buds of P.

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In another experimental manipulation, conducted in Australia, Bickel assessed the effects of air exposure on Cabomba caroliniana regeneration and the influence of temperature, shade, clumping, and humidity on this response. Increasing fragment mass loss decreased the potential to regenerate healthy plants and thus, it reduces the potential of new invasions. Both studies show that vegetative propagules fragments of submersed macrophytes are still able to sprout after relatively long periods of air exposure.

Boating activities represent an important target for management actions to prevent spread of invasive macrophytes. They found a predominance of mature individuals dispersing overland. Dispersal occurred mainly when rice fields became shallow due to drainage. Dispersal rates were positively correlated with rainfall in afternoon periods and high humidity, dew, or fog during sunrise and morning. These findings have great potential in strategies to reduce invasion rates by this invertebrate. A large-spatial-scale investigation on pathways of fish introductions in Neotropical reservoirs was conducted by Ortega et al.

These authors evaluated the importance of different pathways using data from 57 reservoirs in Brazil. Fish farming is the most important pathway of introduction in these Neotropical reservoirs.

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Fish stocking and the constructions of reservoirs, which eliminate natural barriers, such as waterfalls, are also important pathways. Despite the fact that stocking programs with non-native species should have been abandoned in Brazil, fish farming using non-native species is expanding. The authors recommend efforts to develop safer techniques to avoid accidental releases and more sustainable practices when rearing fish. The degree of invasibility of an ecosystem by AIS is related to several abiotic factors, such as water and sediment physico-chemistry, hydrological regime, and nutrient supply.