So let us bond together for the greater good and work together. If we work together and each other does our part, we can make a huge difference. I hope that many people will join this important but relative rare idea of a volunteer citizen science monitoring network. Since we need to raise awareness and solve this important problem!

Invasion Biology

Invasive species are one of the greatest threats to marine biodiversity by reducing biodiversity and causing homogenization of our oceans (Tsutsui et al., 2000). Successful marine invaders such as the European Crab, Carcinus maenas, replace globally rare species with itself, a globally common species. Although this raises alpha-diversity in a site; more importantly, beta-diversity on a global scale is reduced. Bioinvasions are considered an important component of global change since they act on large scales and act synergistically with other environmental factors and problems (Vitousek et al., 1996). As a discipline, marine invasion ecology started in the 1970s and is still in its infancy. So far, only the transport vector and impacts are understood, but only some of the huge numbers of invaders have been accounted for, and even fewer marine bioinvasions have been comprehensively observed. The reason for the establishment of successful marine invasive species is still hotly debated and few answers have been agreed upon. Progress for marine ecology has been slow and minimal due to lack of quantitative data.

Invasive species have been documented to cause a decline in species density and richness that has led to major ecological impacts (Ebling et al., 1959). For example, C. maenas is responsible for the decline and collapse of species such as Katelysia scalerina,Mya arenaria, Cancer magister, as well as many other species, because this crab is a voracious omnivore and skilled competitor (Smith et al., 1955; Ropes, 1968; Walton et al.; MacDonald, 2000). Yet an important question for marine conservation biologists is “What are the characteristics of a successful global marine invader?”

Characteristics of a good invader: Based on the biology of Carcinus maenas

Determining general characteristics of successful marine invaders is important to understanding and preventing further marine bioinvasions, but the answer still remains an elusive challenge (Carleton 1996; Cohen et al. 1995). Yet scientists can study C. maenas, the most successful marine invader, to hopefully shed light on, and possibly understand the important biological characteristics of a good marine invader. This could help to identify strategies for recognizing potential future marine invaders and susceptibility of marine environments and areas to certain invaders. This could lead to better-informed policies and prioritizing monetary resources and time for the monumental problem of marine bioinvasions. Once an invasion occurs, eradication and control of the bioinvader is hard or impossible, so prevention is critical.

Carcinus maenas possesses important characteristics to not only enable it to be transported but also to thrive when it reaches new habitat. Firstly, C. maenas has a planktonic larval stage that allows it to be transported by the vector of ships’ ballast water (Carleton, 1987). Secondly, C. maenas is an excellent osmo-regulator, therefore it is a euryhaline species that can tolerate ranges of salinity from 35 down to 4 parts per thousand (Crothers, 1967). The crab can also withstand temperatures in the range of 22 to –1°C (Cohen et al., 1995). This allows C. maenas to inhabit a diverse range of marine ecosystems. Another important characteristic is that C. maenas is an omnivore and therefore food is usually not a limiting agent (Walne & Dean 1972; Lohrer et al., 2002). So by having the characteristics of a generalist, C. maenas can endure a wide range of environmental conditions, possibly explaining why the species has obtained its extensive global invasive range.

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