Comparison of carbon and nitrogen turnover in normally grown and deformed foraminifera

Abstract In this study, we investigated the feeding behavior of deformed and normal benthic foraminifera (Protista, Rhizaria) of the species Ammonia veneta . The degree of deformation was visualized by scanning electron and light microscopy. Food uptake and assimilation were quantified in undeformed, slight deformed (1–3 abnormal chambers), and heavy deformed (irregular coiling) individuals using isotopic labeling and confocal microscopy. Specimens were collected from the Belle Isle Marsh (Boston, USA) and maintained under controlled laboratory conditions. After a three-day incubation, slight deformed individuals showed food uptake and isotopic enrichment comparable to undeformed specimens. In contrast, heavy deformed foraminifera exhibited significantly reduced carbon and nitrogen assimilation, as well as a lower number of ingested food particles. Confocal observations further indicated reduced food processing in heavy deformed individuals. These results demonstrate that pronounced morphological deformities are associated with impaired feeding and assimilation performance. Our findings highlight that severe test deformation can substantially affect physiological functioning and should be carefully considered when selecting specimens for laboratory experiments or observing them in polluted areas.