Invasive Species: introduction, impact, management, and policy (Part 1)

Written By: Emma Fain

Introduction to invasive species (Part 1 of 4)

Most people may hear or read about non-native species introduced to the United States by media, such as the recently reported 10-foot long Arapaima in the Caloosahatchee river with a voracious appetite for Florida native fish or the Burmese python that was reported to have consumed an entire crocodile to its own death (CBS Miami, 2021; Pappas, 2019). Although the exotic pet trade has been blamed for many introduced species, nonnative species are frequently introduced and distributed by human related activities, such as roadways, airports, and shipping ports (Roth, 2019). Invasive species impact the world and are a global threat due to native species displacement and impairment of natural resources humans rely on (Paini, et al., 2016). Invasive species can cause harm to animals, humans, or plant health (Executive Office of the President 2016; FDACS, 2021; Reaser, et al., 2020). This article series will discuss (1) invasive species characteristics, (2) modes and pathways of introduction, (3) impact of invasive species, and (4) policies and management to detect and prevent invasive species introduction.

Invasive species spread among continents have historically been from natural introductions, such as hurricanes and sea drift (Cox & Moore, 2005; Preston, et al., 2004). Therefore, the introduction of invasive species was once an unlikely event due to biogeographic barriers, such as land and water, that prevented the dispersal of non-native species. As human exploration of the world’s regions expanded, trade of non-species for livestock, crops, and exotic pets were distributed across non-native ranges. Today, the number of introduced invasive species is uncharted territory for humans, causing economic damage ranging from a hundred billion dollars to 3-5 trillion dollars and displacement of valuable native species (FDACS, 2021; Marbuah, 2014, Pimental, et al., 2005).

Prevention of an invasive species introduction is the most effective strategy to prevent environmental and economic impacts. However, if an invasive species bypasses initial detection, it must be removed from the ecosystem immediately to prevent spread. Although non-native species can become invasive species, it is important to note that introduced non-native species have only a one in ten chance of becoming invasive (Williamson and Fitter, 1996). Therefore, eradication of all non-native species would be impractical, especially when communities depend on non-native species for crops, livestock, biological control, and are enjoyed as household pets (Pimente, et al., 2000). For instance 98% of the United States Food System consists of non-native species with a value of 800 billion dollars per year (Mooney & Cleveland, 2001). Therefore, invasive species must be prioritized by risk to natural resources to form an effective management strategy.

Laws and regulations to protect the United States against harmful or potentially harmful non-native species range from 1899 to 2016 (FWS, 2012). However, legislation from Congress concerning invasive species has not been passed since 2004. Only recent policies passed concerning invasive species were addressed by executive order. The United States is not the only one lacking in recent legislation pertaining to invasive species; only 60 of 123 member states of the United Nations have officially endorsed the Sustainable Development Goals to manage invasive species in natural areas (UN, 2021). Although only 9 years are left to meet the United Nations 2030 Sustainable Development Goal deadline, there is still time to preserve biodiversity, restore the functioning of those ecosystems, and secure a future that cultivates human well-being.

Part 1 of this article series will discuss what qualifies as an invasive species. Invasive species spread depends on biological advantages and environmental conditions that foster the proliferation of invasive species. 

Invasive species characteristics

Invasive species are organisms (e.g. plants, animals, pathogenic bacteria) that are introduced to a new environment and have a biological or environmental advantage. An environmental advantage allows the displacement of native species due favorable environmental factors such as spring temperature conditions, altitude, soil moisture, and/or lack of natural enemies. In addition, an invasive species may also have a biological advantage that allows proliferation outside native ranges and outcompete native species including the following (Leiblein-Wild, et al., 2014):

• Rapid reproduction rates

• Resilient seed germination (seed to sprout)

• Rapid growth rates

• Resistance to predation

The disruption of invasive species to native ecosystems can result in economic impact or harm to animal, human, or plant health (Executive Office of the President 2016; FDACS, 2021; Reaser, et al., 2020). In fact, some invasive species, specifically plants, have a distinct hazard label for its danger to agriculture, natural resources, and human and animal health. Those invasive plant species are recognized as a noxious weed by the federal government and most state governments. Noxious weeds are illegal to introduce, possess, move, or release. Currently, 46 out of 50 states have additional noxious weeds listed from the federal list (USDA, 2021). For example, the Brazilian pepper tree (Schinus terebinthifolius Raddi) is listed as a Florida state noxious weed, but is not listed on the federal noxious weed list. This is because states may determine that an non-native species is a risk based on the human activity, climate, topography, agricultural resources, and natural resource harm in that region. Florida is an especially vulnerable state to invasive species introduction due to the subtropical climate, high number of shipping ports, agricultural activity, increasing population, and tourism attraction. Currently, one third of plant species are nonnative that grow naturally in Florida without cultivation. Management of invasive plant suppression costs approximately 30 million taxpayer dollars in natural areas and waterways (FDACS, 2021). 

Figure 1: Common ragweed growing in recently burned natural areas in Southwest Florida. Photo taken by Emma Fain in May 2019

Invasive species are typically non-native but there is an argument in the scientific community that biological invasions could include native species (Reaser, et al., 2020; Valéry, et al., 2009). For example, common ragweed (Ambrosia artemisiifolia L.) is native in the United States but can dominate in vegetative coverage (Figure 2). Invasive specie traits of common ragweed include long lasting viable seeds (over 40 years), rapid growth rates, and allergy hazards to people due to the high levels of pollen that may cause hay fever and dermatitis (Leiblein-Wild, et al., 2014). However, the United Nations and the United States consider an invasive species as a non-native organism outside its native range (also known as an “alien” and “exotic” species). Therefore, for the purpose of this paper, the term “invasive species” will refer only to introduced non-native species. References henceforth to common ragweed will only refer to those non-native ranges known to be invasive in Europe. Additionally, although the Coronavirus (SARS-CoV-2) is an excellent example of spread to new regions due to global interconnectedness, viruses are generally not considered as an “organism” in basic biology and therefore will not be discussed as an invasive species (Cambell & Reece, 2009).

Those ecosystem services impacted by invasive species become impaired. Human activities also foster the proliferation of invasive species and have been addressed in policies due to global connectedness. The next part of this article series will explore mode and pathways invasive species introduction. 

Part 1 References

Campbell, N., Reece, J. (2009). Biology - 8th Edition.

CBS Miami (2021). Florida’s New Invasive Species Is A 10-Foot Long River Monster. CBS Miami 4. Retrieved March 19 from: https://miami.cbslocal.com/2021/03/19/florida-new-invasive-species-fish-arapaima-river-monster/. 

Executive Office of the President (2016) Executive Order 13751, 81 FR 88609-88614, 5 December 2016.

[FDACS] Florida Department of Agriculture and Consumer Services. (2021). Invasive Non-Native Plants. Retrieved February 25, 2021 from: https://www.fdacs.gov/Forest-Wildfire/Our-Forests/Forest-Health/Invasive-Non-Native-Plants 

[FWS] United States Fish and Wildlife Service. (2012). Laws and Regulations - Invasive Species. Retrieved on March 22, 2021 from: https://www.fws.gov/invasives/laws.html. 

Leiblein-Wild, M. C., Kaviani, R., & Tackenberg, O. (2014). Germination and seedling frost tolerance differ between the native and invasive range in common ragweed. Oecologia, 174(3), 739-750.

Marbuah, G., Gren, I. M., & McKie, B. (2014). Economics of harmful invasive species: a review. Diversity, 6(3), 500-523.

Mooney, H. A., & Cleland, E. E. (2001). The evolutionary impact of invasive species. Proceedings of the National Academy of Sciences, 98(10), 5446-5451.

Paini, D. R., Sheppard, A. W., Cook, D. C., De Barro, P. J., Worner, S. P., & Thomas, M. B. (2016). Global threat to agriculture from invasive species. Proceedings of the National Academy of Sciences, 113(27), 7575-7579.

Pappas, S. (2019). Python Swallows Crocodile Whole. Photographer Captures Every Last, Grisly 'Bite.' Live Science. Retrieved March 19 from: https://www.livescience.com/65904-python-swallows-crocodile-whole.html. 

Pimentel, D., Lach, L., Zuniga, R., & Morrison, D. (2000). Environmental and economic costs of nonindigenous species in the United States. BioScience, 50(1), 53-65.

Pimentel, D., Zuniga, R., & Morrison, D. (2005). Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological economics, 52(3), 273-288.

Preston, C. D., Pearman, D. A., & Hall, A. R. (2004). Archaeophytes in britain. Botanical journal of the Linnean Society, 145(3), 257-294.

Reaser, J. K., Frey, M., & Meyers, N. M. (2020). Invasive species watch lists: guidance for development, communication, and application. Biological Invasions, 22(1), 47-51.

Roth, A. (2019). Why you should never release exotic pets into the wild. National Geographic. Retrieved March 19, 2021 from: https://www.nationalgeographic.com/animals/article/exotic-pets-become-invasive-species

[UN] United Nations. Department of Economic and Social Affairs (2021). The 17 Goals. Retrieved March 21, 2021 from: https://sdgs.un.org/goals.

[USDA] United States Department of Agriculture. (2021). Ballast water. Retrieved March 07, 2021 from: https://www.invasivespeciesinfo.gov/subject/ballast-water.

Williamson, M., & Fitter, A. (1996). The varying success of invaders. Ecology, 77(6), 1661-1666.

Valéry, L., Fritz, H., Lefeuvre, J. C., & Simberloff, D. (2009). Invasive species can also be native…. Trends in Ecology & Evolution, 24(11), 585.