Amphibalanus amphitrite is an intertidal barnacle. The reproductive biology of this hermaphrodite species is an interest of research due to its ecological role as biofouling. A survey applying purposive sampling was conducted at the Teluk Penyu area of Cilacap Regency, Central Java, to evaluate A. amphitrite reproductive aspects based on the presence of eggs, embryos and larvae in the mantle cavity. The barnacles were collected monthly in September 2015 up to May 2016 (N=180), the seawater salinity and pH were recorded and so the lunar phase of respected sampling time. The result showed that the barnacle had the lobular type of testis, the ovaries contained 135 – 950 eggs with a diameter of 44 – 95 µm. The embryos had ovoid shape with the long axis of 75 - 177 µm and short axis of 45 – 90 µm. The embryos were not detected in the mantle of barnacles taken in October, November, and April, while the nauplius larvae were only found in September, March, and May. The egg number decreased from September to November 2015 then it increased thereafter (December 2015 – May 2016). The egg diameter was varied from September – November 2015, but it steadily increased from December 2015 to March 2016. The increase in egg diameter was a coincidence with the lunar phase from the first quarter to new moon of the following cycle. Further study is necessary to elucidate the environmental factor affecting A. Amphitrite.

Romanus Edy Prabowo

Gratiana Ekaningsih Wijayanti