## 4 Results
### Benthic Framinifera  
Seven species (33a, S17, S30, S36, S44, S61B and S92) exhibited a low number of specimens and were, therefore, not used for the statistical analysis. Overall, a total of 109 benthic foraminiferal species were recognized. The assemblages were dominated by hyaline (69.1 \(\pm\) 19.7%) forms, followed by porcelaneous (22.2 \(\pm\) 20.4%) and agglutinated (8.7 \(\pm\) 7.1%) wall-type forms (Figure 6) (Table S3). Infaunal groups represented 62.8 \(\pm\) 23.1% of the assemblages with a clear West-East gradient. Higher percentages of infauna were recorded around the Gargano promontory and at the shallowest stations in the southern part of the investigated area (Figure 6). The Hill varied from 0.83 to 3.48 (2.56 \(\pm\) 0.6), whereas Fischer \(\alpha\) index ranged from 0.91 to 36.13 (12.21 \(\pm\) 6.12). Both these diversity indices exhibited the lowest values at the shallow stations (i.e., close to the coast) in the northern and central parts of the study area (Figure 6). The most abundant taxa were _Uvigerina mediterranean_sis (11.5 \(\pm\) 13%), _Ammonia parkinsoniana_ (7.7 \(\pm\) 16.4%), _Bulimina elongata_ (5.7 \(\pm\) 11.4%), _Bulimina marginata_ (5.2 \(\pm\) 8.4%), _Cassidulina carinata_ (5.1 \(\pm\) 6.0%), and _Bolivina spathulata_ (4.2 \(\pm\) 5.5%).  
The most important environmental variable in determining compositional changes of the benthic foraminiferal community along the entire bathymetric gradient was OC (R\({}^{2}\) weighted importance >0.035). Other environmental parameters, namely, sand, PLI, Eh, and N had intermediate (R\({}^{2}\) weighted importance range between 0.01 and 0.02) effects on changes in assemblages (Figure 7A). A Gf model was also analysed for two identified depth intervals, namely, 13-28 m and 59-215 m (Figure 7B,C). Sand was the most important variable, followed by PLI, N, and OC at the 13-28 m depth interval (Figure 7B). At deeper intervals (i.e., 59-215 m), OC played a major role in shaping the benthic foraminiferal assemblages, followed by N and sand (Figure 7C).  
We also used the SEM approach to investigate the specific a priori causal hypotheses and direct and indirect relationships to estimate the effect of the three most important environmental parameters for the overall bathymetric gradient and for each depth interval resulting from the Gf on different diversity index (i.e., Hill) and lifestyle (i.e., infaunal) in benthic foraminifera. Path coefficients from SEM indicated a minor effect of depth on OC, sand, and PLI when the entire bathymetric range is considered (Figure 8A), with a negative (standardized path coefficient (SPC) = \(-\)0.35) influence on infauna and a positive influence (SPC = 0.16) on Hill. Sand had a direct negative effect (SPC = \(-\)0.68) on infauna and a positive one (SPC = 0.51) on Hill (Figure 8A). When the depth interval 13-28 m was considered, depth had strong effects on sand, PLI, and N (Figure 8B), with a positive effect on infauna (SPC = 0.14) and a negative one on Hill (SPC = \(-\)0.23). In this interval, infauna is negatively related to sand (SPC = \(-\)0.96), PLI (SPC = \(-\)0.29), and N (SPC = \(-\)0.27). Sand had a direct effect on Hill (SPC = 0.81) and N (SPC = 0.41) (Figure 8B). At deeper stations (i.e., 59-215 m), depth did not seem to affect infauna or Hill (Figure 8C) but had a negative influence on OC (SPC = \(-\)0.43) and N (SPC = \(-\)0.32). Of these two environmental parameters, only N appears to highly influence both infauna (SPC = 0.66) and Hill (SPC = \(-\)0.69) (Figure 8C).  
Figure 7: Relative contribution of environmental variables in shaping the benthic foraminiferal assemblages along three depth ranges (**A**) 13–703 m, (**B**) 13–28 m, and (**C**) 59–215 m. Total nitrogen [N], Pollution Load Index [PLI], Total organic carbon [OC].