بررسي پويايي و ساختار جمعيتي گونه FEROSAGITTA FEROX از شاخه پيكانيان در سواحل استان خوزستان (خليج فارس‌)

Population structure of Ferosagittaferox (Chaetognatha) in the northwest coastal waters of the Persian Gulf

Population dynamics of Ferosagitta ferox (Chactognatha) was carriedout in coastalwaters of Khur-e-Mussaʹs Channel in Khuzestan Province, northwest Persian Gulf. Monthly samples were collected with 300llmmeshsize plankton net in oblique tow fromncar bottom to surface waters. In total,7 speciesof Chaetognaths wereidentified belonging to 1 class (Sagittoidea), 1 order (Aphragmophora), 2 families (Sagittidae and Krohnittidae) and4 generatAidanosagttta, Ferosagitta, Flaccisagitta and Krohnitta) . The identified species included Aidanosagitta bedfordi, A. neglecta, Ferosagitta ferox, Flaccisagitta enflata, F. hexaptera, Krohnitta pacifica and one unknown species. Due to presence and excessive frequency of Ferosagitta ferox in all samples, we focused on its population variationas an indicatorof Chaetognatha. We determined length groups for adult individuals in 4-21mm range with lmm increments. The year round presence of juvenile and small individuals showed the continuous reproduction of F. ferox with two considerable peaks in March and July. The evaluated recruitment indicated that the species has a low growthrate and a long life cycle. • Corresponding