Identification, diversity and distribution patterns of fish larvae in Khark & Kharko Coralline Islands ecosystem – Persian Gulf, by GIS method

Khark & Kharko Islands are the last Northern point for fringing coral reefs in Iranian side of the Persian Gulf. These Coralline habitats are the Protected Area and Wildlife Refugees with the total area of 2400 ha which located in the territory of Bushehr Province. This research carried out during 2006-2007 with monthly sampling from 12 stations, which selected around Islands and inshore waters with maximum depth of 20 meter. Sampling was conducted using by Bongo-Net plankton sampler with 500μ of mesh size. Totally, 1808 specimen from 45 family fish larvae was identified in studied area, including: 21 coralline fish larva families and 24 shore fish larvae such as pelagic and demersal fishes which some of them known as indicator, sentinel or endemic species for coral reef ecosystems. The results was shown that coral reef diversity in coral reefs (Khark & Kharko Islands) is more than other habitats such as estuary and river mouth, creeks, mangrove forest sites, and off shore water of the Persian Gulf and Oman Sea Iranian side. Among Identified families, Clupeidae, Blenniidae, Sillaginidae, Atherinidae and Tripterygiidae; with more abundance were dominant families in studied area. The pick of fish larvae abundance family were estimated in spring. There were significant differences between seasonally abundance and sub areas, but there were not significant differences in diversity indexes between Khark and Kharko stations with coastal stations (p< 0.05). The mean abundance of fish larvae were estimated 18.7083 larvae under 10m² of sea surface, and the mean diversity indexes and evenness were estimated 0.7135 and 0.565342 consequently, that was showed the area is under ecological stress for fish larvae, and wasn’t stable. Therefore, from the ecological point of view, only some of the fish larvae groups as like Clupeidae were dominant. Thus, they were the main cause of the fish larvae abundance change in studied area. Due to geographical location of Khark and Kharko Islands and among the environmental parameters, Its seems that the condition of sea current is the main cause for present or absent and distribution patterns of fish larvae in area. Abundance of fish larvae in west of Islands was higher than eastern parts in the spring. But this condition will be reversed in eastern part of Island and several coastal stations, so that the Islands surrounding clock wise current to cause fish larvae distribution patterns.

Boloceroides spp.

Boloceroides spp. are looking like an untidy mop, this anemone is sometimes seen in sea grass areas on many of our shores. It is possibly seasonal. Sometimes, large numbers are seen (up to 10-20 animals in a trip) and then none at all.  Tiny swimming anemones may sometimes be confused with Sea grass anemones which have translucent tentacles with tiny spots. The swimming anemone harbors symbiotic single-celled algae (zooxanthellae). The algae undergo photosynthesis to produce food from sunlight. The food produced is shared with the sea anemone, which in return provides the algae with shelter and minerals. The oral disk and tentacle muscles are used to obtain, retain, and ingest prey; in Boloceroides spp. tentacles can autotomize if it is needed to evade a predator. Tentacles can control body form by use of their endodermal muscles. Retractors are longitudinal muscles that will aid in withdrawing tentacles and the oral disk if they are exposed to the open air.  This hypothesis is furthered because in comparison to other sea anemones, Boloceroides is loosely attached to its respective substrate, thus allowing the pedal disk to detach quickly resulting in a rapid swimming response. Boloceroides can reproduce both sexually and asexually. As Anthozoans, Boloceroides produce sexually by bypassing the medusa life cycle stage; this allows Boloceroides (and all Anthozoans) to release their egg and sperm creating planula a bilaterally symmetrical, flattened, ciliated, motile larva.

Pempheris vanicolensis (Cuvier, 1831)

Pempheris vanicolensis has reported for the first time from Persian Gulf (Kish Island). Various aspects of the biology of P. vanicolensis Cuvier & Valenciennes, a recent Lessepsian (Suez Canal) immigrant into the Mediterranean, are given. Red Sea and Mediterranean populations were compared, and the results indicate that the spawning season is shortened in the Mediterranean, continuing from April to September, as opposed to year-round in the Red Sea. Descriptions of a ripe ovary and post-larva from the Mediterranean are given. Individuals reach a mean size of 10.8 cm in their first year, and 14.4 cm in the second year. Little change has occurred in the diet of the immigrant population, and both populations feed nocturnally, chiefly on larval and adult stages of planktonic crustaceans. Direct underwater observations on the diurnal behavior of the species show that the fish leave their daytime cave shelter at sunset, congregate at a nearby site and then migrate inshore and disperse into small groups to feed. Before dawn, they reassemble at the cave's entrance, and finally enter it at sunrise, after the school has built up. Observations on Persian Gulf sweepers show that the fish are segregated into size groups, ranging 15–18 cm adults at depths of 3 m.