engleski

The distribution of Mueller’s pearlside Maurolicus muelleri (Gmelin, 1789) early life stages in central-eastern Adriatic Sea

Mueller’s pearlside Maurolicus muelleri (Gmelin, 1789) is a cosmopolitan, mesopelagic species distributed worldwide in tropical and subtropical waters. In the Adriatic Sea, it is found in its central and southern parts. This species is usually found near continental shelf-slope (10-400 m ; Jardas, 1996). Its spawning season lasts all year round, hence their early life stages are found in all seasons throughout the year. Over the last three years (2019-2021) six scientific surveys were carried out in the central-eastern Adriatic Sea (Croatia). Throughout surveys, ichthyoplankton samples were collected by WP2 sampler. In the laboratory, ichthyoplankton samples were analysed under the stereomicroscope coupled with a camera. Each collected fish egg and larvae were photographed, measured, isolated and determined applying a standardized molecular approach (DNA barcoding). In collected ichthyoplankton samples, after DNA barcoding, we established the presence of 275 Mueller’s pearlside early life stages (274 eggs: mean diameter 0.617±0.113 mm, 1 larvae: TL=2.95 mm). The abundance of Mueller’s pearlside eggs varied from 4 to 248 eggs/m2 (mean±SD: 15.15±32.49 eggs/m2). Collected eggs of investigated species were present in the whole area of investigation, but the highest values of their abundance were obtained in the wider area of Jabuka/Pomo pit in each investigated season. This area is known as an area of upwelling (Gačić et al. 1997) therefore, the presence of this and other fish species’ early life stages is expected due to enrichment, food aggregations and physical processes (Lafuente et al., 2002). Abundance values obtained within this study were slightly lower than ones obtained for the same species in the same area of investigation collected in the early 70s of the last century (Gamulin & Hure, 1985 ; 75-620 eggs/m2) and this might be linked to an observed climate regime shift in Adriatic during the last few decades (Grbec et al. 2015).

DNA barcoding, Maurolicus muelleri, eastern Mediterranean

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