J. Hohenegger et al., HORIZONTAL AND VERTICAL SPATIAL MICRODISTRIBUTION OF FORAMINIFERS IN THE SHALLOW SUBTIDAL GULF OF TRIESTE, NORTHERN ADRIATIC SEA, Journal of foraminiferal research, 23(2), 1993, pp. 79-101
The spatial microdistribution of foraminifers in the shallow subtidal
zone of the northernmost Adriatic Sea was examined by the method of qu
adratic sampling on a sample grid. In addition to the distributions at
the sediment surface, the depth horizons down to 5 cm were also inves
tigated in 1 cm steps. The distributions at the sediment surface are p
atchy for all of the more commonly occurring species (Reophax nanus, L
abrospira jeffreysii, Eggerelloides scabra, Spiroplectinella sagittula
, Miliolinella subrotunda, Triloculina affinis, Brizalina striatula, B
ulimina aculeata, Elphidium advenum, Ammonia tepida, Nonionella turgid
a) except Epistominella vitrea which is randomly distributed. Nonionel
la turgida is specialized to feed on diatoms; therefore, it is present
only in the topmost two centimeters, which also represent the oxygena
ted layer of the sediment. In addition to this oxygenated surface zone
, all the other species inhabit burrows of infaunal macrobenthic organ
isms; however, inside these burrows only the oxygenated halo will be c
olonized. Elphidium granosum is frequently found exclusively in these
burrows. In contrast, Spiroplectinella sagittula seems to burrow activ
ely also in the anoxic sediment. The patchiness of the foraminifers ma
y be caused by specific food requirements. The trophic modes are domin
ated by detritus and deposit feeding, and diatoms may be an additional
source of food for Miliolinella subrotunda and Triloculina affinis.