Living deep-sea benthic foraminifera from the Cap de Creus Canyon (western Mediterranean): Faunal–geochemical interactions

• Published in: Deep-sea research. Part I, Oceanographic research papers Oceanographic research papers, 2012-06, Vol.64, p.22-42
• Main Authors: Contreras-Rosales, L.A., Koho, K.A., Duijnstee, I.A.P., de Stigter, H.C., García, R., Koning, E., Epping, E.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Benthic foraminifera; Biological and medical sciences; Biological diversity; Canyons; Chlorophyll; Communities; Correlation; Correlation analysis; Foods; Fundamental and applied biological sciences. Psychology; Geochemistry; Inventories; Marine; Marine ecology; Nitrates; Protozoa; Redox chemistry; Sea water ecosystems; Sedimentary phytopigments; Sediments; Stockpiling; Submarine canyons; Synecology
• ISSN: 0967-0637; 1879-0119
• DOI: 10.1016/j.dsr.2012.01.010

Rose-Bengal-stained benthic foraminifera were sampled along a depth transect from the Cap de Creus Canyon and the adjacent slope. Well-stained individuals were studied in the top 5cm of sediment and the faunal abundances and assemblages were compared against pore-water geochemistry and biochemical composition of the sediment. Total standing stocks (TSS) of foraminifera were positively correlated with the chloroplastic pigment equivalents inventory (CPEinv; here interpreted as food quantity) and the ratio of chlorophyll-a and phaeopigment inventories (Chl-ainv/Phaeoinv; here interpreted as food quality), suggesting food quality as well as quantity play an important role in structuring the foraminiferal community. Food quality and food quantity were also identified by detrended correspondence analyses (DCA) as being the most important environmental parameters shaping the foraminiferal community structure (abundance and faunal composition). In addition, sediment redox chemistry (based here on pore-water nitrate) played an important role in controlling the foraminiferal diversity (H′) as a negative correlation was seen between this parameter and pore-water nitrate penetration depth (NPD). No conclusive evidence of intense physical disturbance on the benthic canyon community was observed, although it could be anticipated in the area due to shelf-water downwelling (SWD) and dense shelf-water cascading (DSWC). However, foraminiferal faunas living in the canyon head and upper canyon environments may profit from the higher organic-matter availability, which is likely to be related to SWD and DSWC. The similarity between the deeper canyon and slope faunas suggests that sediment characteristics and the associated organic-matter transported by SWC and DSWC do not have a permanent effect at these depths. ► We sampled living benthic foraminifera from Cap de Creus Canyon and adjacent slope (Mediterranean). ► Foraminiferal faunas were compared with pore-water chemistry and organic-matter availability. ► Canyon faunas appeared better developed than adjacent slope faunas at similar water-depths. ► Standing stocks and assemblages were controlled by food supply and food quality. ► Redox chemistry appeared to play a secondary role by influencing species diversity.