Feeding ecology and morphometric relationships of white seabream, Diplodus sargus lineatus (Sparidae), endemic species of Cape Verde
Diplodus sargus lineatus (white seabream) is an endemic coastal species in Cape Verde (CV). It is one of the most abundant seabream but has a low marketable value. In this work the feeding ecology of D. sargus lineatus and morphometric relationships were studied for the first time. Feeding indices and coefficients were determined and used along with multivariate analysis to characterise ontogenetic and sexual diet shifts. Diet was diversified and a total 53 food items were identified. Algae composed the majority of the items (36), namely Rhodophyta algae (26), followed by benthic macroinvertebrates (17). Feeding diversity is not related to sex or size classes. When compared with other species from the same genus, D. sargus lineatus showed a rich benthic fauna diet and the largest diet diversity in red algae consumption. This result reflects the rich benthic marine faunal environment and red algae flora availability of CV islands, even though red algae would be rather unusual considering the short coastal area associated with the Macaronesian Archipelagos. Diel diet analysis showed higher feeding activity during the day. Two alien algae species found in D. sargus lineatus diet were first described for CV. These results highlighted the importance of diet studies as ecosystem bioindicators tools. The estimated morphometric relationships showed negative allometries between body height (BH = 0.4163FL + 0.3711), head length (HL = 0.2649FL – 3.6456), ocular diameter (OD = 0.07FL + 0.61) and fork length (FL). Positive allometry and high correlation were found between weight and fork length (W = 0.0001787FL – 3.14).