Vertikale Verbreitung von Sphaeroma terebrans (Isopoda) an untergetauchten Hafenbefestigungsanlagen

Abstract

1.Sphaeroma terebrans andMartesia striata occur on jetty piles in the Conchin harbor (76° 14′ E and 9° 57′ N). 2. On a given jetty pile or log, however, both species live at different depths. There is practically no overlap in their vertical distribution. 3. A total of twelve logs were examined. On seven of these logsSphaeroma holes occured down to a depth of 45 cm below high water level, on the other five down to 60 cm.Martesia holes, however, began to appear on the first seven logs at 60 cm depth and on the other five at 75 cm depth. From these levels they occurred right down to the bottom (maximum depth: 270 cm). 4. It is suggested that this vertical segregation is primarily caused by the greater capacities ofSphaeroma to withstand prolonged periods of exposure to air and by competition for space.