Effects of short-term hypoxia on metabolism and haemocyanin oxygen transport in the prawns Palaemon adspersus and Palaemonetes varians

In summer, high temperatures are combined w ~ t h severe nocturnal hypoxia In the shallow water of Danish fjords. Under these conditions, the prawns Palaemonetes varians (Leach) and Palaem o n adspersus (Rathke) are spatially separated, with the former occupying the areas of highest temperature and lowest oxygen tension. If kept together, P, adspersus shows aggressive behavlour towards P varians. Aerobic/anaerobic respiration and haemocyanin characteristics were measured in laboratory experiments (24°C. 14 ppt). Although the 2 species have similar metabolic rates, P. varians survives severe hypoxia better and has a lower P, (critical oxygen tension, below which respiration is partly or fully anaerobic) than P adspersus. Both species accumulate high levels of lactate during anaerobiosis and remove it at similar rates. The haemocyanin concentration and total oxygen carrying capacity (0.78 2 0.25 mm01 I-' and 2.25 + 0.56 ~ 0 1 % ) of P varians was higher than P. adspersus (0.28 rt 0.07 mm01 I-' and 1.14 + 0.15 vol%). Haemocyanin oxygen affin~ty was always higher in P. vanans regardless of pH, but tile B u i i ~ idctor i-i.44 and i . 4 6 ) and cooperat~vity (nS0. 2 61 + 0.20 and 2.82 t 0.49) were similar for P. varians and P. adspersus, respectively. P. varians is thus better adapted to severe hypoxia than P. adspersus