Life cycles and feeding habits of Syngnathus taenionotus and S abaster in a brackish bay of the Po River Delta
Franzoi, P.; Maccagnani, R.; Rossi, R.; Ceccherelli, V.U.
Marine Ecology Progress Series 97(1): 71-81
We investigated the population structure, life cycles and gut contents of 2 species of pipefish, Syngnathus taenionotus and S. abaster, in a brackish embayment of the Po River Delta (North Adriatic Sea). These 2 species inhabit the nearshore environment of the bay where the sandy bottom is covered by macroalgae, and were sampled for 1 yr. The main differences in life history traits between S. taenionotus and S. abaster respectively can be summarized as follows: life span is about 24 vs 17 mo; reproductive season begins in February vs March, and lasts 5 vs 4 mo; average length of fingerlings at the time they hatch from the male brood pouch is 20.3 (+- 1.2) vs 13.5 (+- 1.0) mm; egg incubation period is 2 mo vs 1 mo; average number of ripe eggs per mature ovary is 46 (+- 9) vs 104 (+- 40); average number of embryos incubated by male is 84 (+- 17) vs 109 (+- 27). Finally, the sex ratio in the reproductive pete for food resources, remaining almost completely segregated in 2 different foraging micro-habitats population is more male-biased in S. taenionotus than in S. abaster. The 2 species probably do not compete for food resources, remaining almost completely segregated in 2 different foraging micro-habitats during most of their life span. The new-born spring individuals of both species feed almost exclusively while the larger S. taenionotus become zooplanktivorous.