A comparative study of the physiological condition of native and invasive crayfish in Croatian rivers

Abstract

The physiological condition of two invasive crayfish species identified in Croatian rivers (Orconectes limosus and Pacifastacus leniusculus) was compared with that of native crayfish populations (Astacus astacus and A. leptodactylus). Hepatosomatic, gonadosomatic and abdominal muscle indices were examined for all four species and within a specific invadernative pair. The results demonstrate that invasive crayfish had better overall physiological condition when compared to native species, with a higher energy content of the hepatopancreas, abdominal muscle and gonads in invasive than in native species, with the exception of A. leptodactylus females which demonstrated an increased ability to allocate energy to reproduction in comparison with other species. These results also indicate that A. astacus is physiologically more unstable than A. leptodactylus and thus more likely to be outcompeted and replaced by non-indigenous crayfish species.

Disturbance in invasion? Idiopathic necrotizing hepatopancreatitis in the signal crayfish Pacifastacus leniusculus (Dana, 1852) in Croatia

“…Immediately before dissection, each individuals' nerve cord was rapidly cut ventrally from the thorax to the end of abdomen, according to available international guidelines for humane killing of crayfish (Conte et al, 2021); since no institutional or national ethical guidelines exist for crayfish. Recorded body length and weight data and hepatopancreas weight were used to calculate condition indices: (a) body condition index (Fulton condition factor; FCF = W t /TL 3 ) and (b) hepatosomatic index (HSI = W hep * 100/W t ), which are frequently used to assess the condition and overall health of the animal by determining their nutritional status and energy reserves (Carmona-Osalde et al, 2004;Lucić et al, 2012;Streissl & Hödl, 2002). Unexpectedly, during pilot dissections and hepatopancreas sampling for a wider study on microbiome of F I G U R E 1 Sampling locations along the invasion range of the signal crayfish Pacifastacus leniusculus in the Korana River in Croatia (black triangles).…”

Immune Response in Crayfish Is Species-Specific and Exhibits Changes along Invasion Range of a Successful Invader

“…Since immune response is considered an important fitness component [ 78 ] and dependent upon animal (physiological) condition, we measured several condition parameters in addition to immune parameters: (i) Fulton’s condition factor (FCF = W/TL 3 × 100; where W = weight (g), and TL = total body length (mm) of the individual), which is used as a proxy for individual’s body condition [ 79 ], and (ii) hepatosomatic index (HSI = HW/BW; where HW = hepatopancreas weight (g), and BW = body weight (g)), which is indicative of an individual’s energy status [ 80 ]. These indices are frequently used to determine health and fitness of crayfish individuals [ 37 , 81 , 82 , 83 , 84 ] and are also used as proxy measures of fitness in aquatic animals [ 85 ].…”