Influence of Hypoxia on Bacteremia in the Dungeness Crab, Cancer magister

Abstract

We examined the possibility that decreased environmental oxygen can elevate the levels of indigenous bacteria in the hemolymph of Cancer magister. Crabs were exposed to air-saturated and hypoxic (50% air-saturation) water for 3 days and levels of culturable bacteria in hemolymph were measured every 24 h as the total number of colony-forming units (CFU) per milliliter of hemolymph. Bacteremia increased after 24 h of exposure to hypoxia and persisted for 72 h, whereas crabs exposed to normoxia had no measurable change in number of culturable bacteria. The predominant persistent bacteria in the hemolymph was isolated and identified by DNA sequence-based methods as Psychrobacter cibarus. Crabs were injected with P. cibarus or with buffered saline as a control after 3 h of hypoxia. Levels of culturable bacteria were significantly higher in hypoxic crabs than in normoxic ones (about 2500 versus 1000 CFU ml(-1) 80 min post-injection, respectively), and circulating levels of oxygen were significantly reduced in infected animals compared to uninfected ones after 48 h in hypoxia and after 72 h in air-saturated water post-injection. These data demonstrate that P. cibarius is present in Dungeness crabs, that environmental hypoxia can dramatically elevate levels of persistent bacteria, and that hypoxia in the presence of hemolymph bacteria may ultimately reduce immune and respiratory ability.

Haemolymph microbiome of the cultured spiny lobster Panulirus ornatus at different temperatures

“…Psychrobacter of family Moraxellaceae have been described to have antagonistic effects against pathogenic bacteria 44,45 , lipolytic activity and the ability to reduce nitrate to nitrite 46 . The persistence of Psychrobacter has been reported previously in the haemolymph of Dungeness crab Cancer magister 47 . On the other hand, Chistoserdov, et al .…”

“…edwardsii juveniles make a full recovery within 3 weeks following removal of 10–15% of haemolymph volume. Moreover, several studies that conducted repeat sampling from individual crustaceans 23,47,63–66 and Evans 23 found no decrease in protein level. In the present study, lobsters were euthanised due to the large volume of haemolymph required for several immune and bacterial assays.…”

Tail Fan Necrosis syndrome in decapod crustaceans: A review

“…Stressed lobsters and other decapods rapidly acquire bacteria in the haemolymph when immunologically compromised by capture, or even by stress from the noise at the time of capture (J. B. Jones, personal observation; Celi et al., 2015; Fotedar et al., 2001; Ridgway et al., 2007; Scholnick & Haynes, 2012). The influence of environmental stress pre‐sampling on bacteraemia and defence responses and the time to initiate those responses are areas of critical importance but have seldom been addressed in the context of TFN syndrome.…”

Shellfish as reservoirs of bacterial pathogens

“…A recent prior exposure to Vibrio campbellii in these animals can enhance the ability of blue crabs to render bacteria non-culturable [18]. The harmful effects of hypoxia have also been found in the Dungeness crab, Cancer magister [19]. A majority of juvenile edible crabs, Cancer pagurus harbor cultivable bacteria in the hemolymph, but most of them have only small numbers of bacteria, which does not appear harmful to the host.…”