Physical habitat characteristics of freshwater crayfish Cambaroides similis (Koelbel, 1892) (Arthropoda, Decapoda) in South Korea

Abstract

Background: Cambaroides similis is an endangered candidate species living in the stream of South Korea. Freshwater crayfish is known to decline rapidly not only domestically, but also internationally. Its decline is projected to be further exacerbated due to climate change. Understanding physical characteristics of the habitat is crucial for the conservation of an organism. However, comprehensive data regarding the distribution and physical habitat characteristics of C. similis are currently unavailable in South Korea. Thus, the objective of this study was to ascertain preferred ranges for water depth, current velocity, and streambed substrate of C. similis using Weibull model. Results: In this study, C. similis was found at 59 sites across 12 regions in South Korea. Its optimal water depth preferences ranged from 11.9 cm to 30.1 cm. Its current velocity preferences ranged from 9.8 cm s -1 to 29.1 cm s -1 . Its substrate preferences ranged from -5.1 Φ m to -2.5 Φ m . Median values of central tendency were determined as follows: water depth of 21.4 cm, current velocity of 21.2 cm s -1 , and substrate of -4.1 Φ m . Mean values of central tendency were determined as follows: water depth of 21.8 cm, current velocity of 22.0 cm s -1 , and substrate of -4.4 Φ m . Mode values of central tendency were determined as follows: water depth of 21.7 cm, current velocity of 20.1 cm s -1 , and substrate of -3.7 Φ m . Conclusions: Based on habitat suitability analysis, physical microhabitat characteristics of C. similis within a stream were identified as Run section with coarse particle substrate, low water depth, and slow current velocity. Due to high sensitivity of these habitats to environmental changes, prioritized selection and assessment of threats should be carried out as a primary step.