Ichthyoplankton of Inner Part of Izmir Bay, Aegean Sea (2000-2005)

Abstract

Inner Bay of Izmir was an important "point of pollution" in terms of domestic and industrial pollution of Mediterranean region at the end of 1990s. From the beginning of 2000s, however, positive effects on all of the groups of living organisms in the marine ecosystem has begun to be seen as a consequence of avoidance of the pollutants. As a result of evaluation on seasonal surface plankton samplings between 2000 and 2005, present study related to the species abundance, distribution evaluated with the abiotic environmental variables such as temperature, salinity and dissolved oxygen. Spawning situation has been demonstrated and compared with the previous studies in the Inner Izmir Bay fishes. During the study period, a total of 8727 eggs and 273 larvae were examined. 7 species of eggs and 13 species of larvae were determined. Availability rate of the species tended to increase from the spring to the summer seasons. The dominant species in the Inner Bay is Engraulis encrasicolus (Linnaeus, 1758), being responsible for 98% the eggs and 51% of the larvae. 6.59% of the obtained eggs, however, were found be dead. Being one of the other small pelagic species, Sardina pilchardus (Walbaum, 1792) continues to lay eggs at very low levels. Parablennius gattorugine (Linnaeus, 1758) larvae (12%), Gobius niger Linnaeus, 1758 (11%), and Salaria pavo (Risso, 1810) (9%) are other important species in the region. At the lowest level of dissolved oxygen E. encrasicolus, Callionymus pusillus Delaroche, 1809, Buglossidium luteum (Risso, 1810) eggs and larvae of G. niger, Blennius ocellaris Linnaeus, 1758, Parablennius tentacularis (Brunnich, 1768) 1.68 mg/L were found. The fact that Blenniidae larvae were detected again at high level in the Inner Bay was found to be related to increased rate of light transparency. Part of the Inner Bay of Izmir that is richest in eggs-larvae is south of the middle part (offshore of Cakalburnu Lagoon) and the part that is richest in larvae is Yenikale Lighthouse located on outer part of the Bay. The weak currents which start from Yenikale Lighthouse doesn't much effect to eggs and larval drift.