Crayfish effects on seeds and seedlings: identification and quantification of damage

Abstract

1. The red-swamp crayfish (Procambarus clarkii) is an invasive species and an important pest of wet-seeded rice fields (Oryza sativa) in California (U.S.A.) and in Portugal. Our work quantifies rice consumption and non-consumptive destruction and identifies the types of direct damage inflicted by crayfish. 2. The following fractions were quantified in the presence and absence of crayfish and at 3 and 6 days of rice development: (1) non-germinated seeds, (2) damaged seeds, (3) seeds not recovered, (4) intact rooted seedlings, (5) rooted damaged seedlings, (6) uprooted intact seedlings, (7) uprooted damaged seedlings. 3. Coarse particulate organic matter (CPOM) fragments produced during the feeding process were <2% of the material removed by crayfish. 4. Damage occurred with or without uprooting of the plants, but the incidence of uprooting without consumption was low (1.4%). 5. Consumption of recently developed parts of the rice plant was the main cause of damage and the observed effect was stronger on 6-day-old than on 3-day-old seedlings. Seedlings were more affected by crayfish than were seeds. 6. Crayfish affected the majority of seeds and seedlings available although consumption was low: 0.015 g dry weight (DW) rice g )1 wet weight (WW) crayfish per 12 h at 3 days and 0.063 g DW rice g )1 WW crayfish per 12 h at 6 days. 7. Our results are important for the mitigation of crayfish related problems in rice fields and for understanding the mechanisms of crayfish-macrophyte interactions.

Ecosystem services provided by waterbirds

“…Red-swamp crayfish Procambarus clarkii are a widespread exotic species and major pest in ricefields in California and the Iberian Peninsula, causing significant damage to the seeds and seedlings (Anastacio, Parente & Correia, 2005) as well as to dykes by digging burrows. Wading birds such as storks, herons and ibises are important predators of these crayfish (Negro et al, 2000;Tablado et al, 2010).…”

Population dynamics of the invasive crayfish (Procambarus clarkiiGirard, 1852) at two marshes with differing hydroperiods

“…In Portugal this species was introduced from Spain in the 1970's (Ramos and Pereira, 1981) and spread rapidly. It is considered an agricultural pest because of its burrowing activity which causes serious damage in dams and levees and because it consumes young rice plants (Grigarick, 1984;Anasta´cio et al, 2005aAnasta´cio et al, , 2005b.…”

Desiccation survival capacities of two invasive crayfish species

“…The signal crayfish Pacifastacus leniusculus (Dana, 1852) and the red swamp crayfish, Procambarus clarkii (Girard, 1852) are two North America native crayfish species with worldwide distribution due to their economic importance, but also due to their high dispersal abilities, fast growing populations and wide niches (Hobbs et al, 1989). Severe negative impacts on invaded areas are attributed to these two crayfish species, such as competition with native species (Nyström, 1999), dissemination of the crayfish plague (Diéguez-Uribeondo et al, 1997), habitat and ecosystem changes (Geiger et al, 2005), negative effects on amphibian populations (Nyström, 1999; Cruz et al, 2008) and losses on economic activities such as rice production (Anastácio et al, 2005). In the Iberian Peninsula these two crayfish were first introduced into Spain nearly at the same time, P. clarkii in 1973 and P. leniusculus in 1974 respectively, for aquaculture purposes (Diéguez-Uribeondo et al, 1997;Alonso et al, 2000).…”