Impacts of ocean acidification on intertidal benthic foraminiferal growth and calcification
Fig 5
Scanning electron micrographs (SEM) images of live specimens of Elphidium williamsoni cultured at pH 8.1 (A & B), pH 7.9 (C & D), pH 7.7 (E & F) and pH 7.3 (G & H).
(A) SEM image of side view of the apertural region showing numerous teeth and tubercles. A frustule of the diatom species Navicula sp. and organic material detritus are visible by a septal bridge. (B) Higher magnification of the test surface of specimen A. (C) SEM image of side view of apertural region, showing numerous teeth and tubercles with some impaled frustules of the diatom species Navicula sp. (D) Higher magnification of the smooth test surface of specimen C. (E) SEM image of side view of the apertural region, where signs of dissolution and cracking are clearly observed. Teeth and tubercles are less sharp with rounded shape. No frustules of diatom species are observed. (F) Higher magnification of the test surface of specimen E affected by dissolution and cracking processes. (G) SEM of side view of the apertural region showing a reduction in the number of teeth and tubercles. Dissolution and cracking processes are clearly observed in multiple structures with a severe effect on septal bridges and sutures. No frustules of diatom species are observed. (H) Higher magnification of the test surface of specimen G, showing several test wall layers, septal bridges and sutures affected by dissolution and cracking processes. (*) White asterisks show the presence of diatom Navicula sp. ← Yellow arrows show areas affected by dissolution.