Faulkes and colleagues, 2012

Faulkes Z, Feria TP, Muñoz J. 2012. Do Marmorkrebs, Procambarus fallax f. virginalis, threaten freshwater Japanese ecosystems? Aquatic Biosystems 8: 13. http://dx.doi.org/10.1186/2046-9063-8-13

Abstract

Background

One marbled crayfish, Marmorkrebs, Procambarus fallax f. virginalis (Hagen, 1870), was discovered in a natural ecosystem in Japan in 2006. Because Marmorkrebs are parthenogenetic, they could establish a population from only a single individual, and thus pose a risk for becoming established in Japan, as they have in other countries. There are two major reasons to be concerned about the possibility of Marmorkrebs establishing viable populations in Japan. First, Japan’s only endemic crayfish, Cambaroides japonicus (De Haan, 1841), lives throughout Hokkaido and is endangered. Introduced Marmorkrebs are potential competitors that could further threaten C. japonicus. Second, Marmorkrebs live in rice paddies in Madagascar and consume rice. Marmorkrebs populations could reduce rice yields in Japan.

Results

We created five models in MaxEnt of the potential distribution of Marmorkrebs in Japan. All models showed eastern Honshu, Shikoku and Kyushu contain suitable habitats for Marmorkrebs. Hokkaido, the main habitat for C. japonicus, contained much less suitable habitat in most models, but is where the only Marmorkrebs in Japan to date was found.

Conclusions

Marmorkrebs appear to be capable of establishing populations in Japan if introduced. They appear to pose minimal threat to C. japonicus, but may negatively affect rice production.

Keywords: None provided.

Mięsikowski and colleagues, 2012

Mięsikowski M, Napiórkowska T, Templin J, Wilczyńska B. 2012. Embryonic development of Marmokrebs (Procambarus fallax forma virginalis, Hagen 1870). Acta Biologica Cracoviensia Series Botanica 54(suppl. 1): 69. http://www.ib.uj.edu.pl/abc/pdf/suppl54_1/sup_54_s1.pdf#page=33 (Conference abstract only)

Abstract

Marmokrebs (sic) are very interesting objects of study because of the possibility of parthenogenetic development. Attention was paid to him in the 90s the last century when a German pet shops came as breeding animal. Currently, the wild population of this crayfish exist in Eastern Europe, North America, Madagascar and Japan (Jones et al., 2008; Faulkes, 2010). This species due to the specific way of reproduction, high fecundity, small food selectivity and ease of adaptation to different environmental conditions is treated as a potentially invasive species. It is believed that it could threaten like native populations of aquatic invertebrates and fish (Scholtz et al., 2003).

Research on development of marmokreb (sic) were conducted in laboratory conditions in an aquarium with a capacity of 90 liters. In each breeding aquarium was placed on three females. After laid eggs the females were transferred to a separate tank. Water temperature which kept incubation female was about 22°C and pH 7.90–8.15. In order to observe the successive stages of development were taken from the incubating female three eggs every 12 hours. It was made biometric measurements of embryos and photographed the next stages of development.

It was found that the breeding conditions Procambarus fallax development take about 30 days. Eggs have spherical shape with diameter of 1.5 mm. Identified 10 embryonic stages, which coincide with the observations of Alweys (sic) & Scholtz (2006).

Keywords: None provided.

Note: Contrary to the above, there are no known wild populations of Marmorkrebs in North American or Japan.