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Trophic interactions between preadult and adult Pomatoschistus minutus and Pomatoschistus microps and young Platichthys flesus occurring in inshore waters of the Gulf of Gdańsk (Southern Baltic)

Złoch I., Sapota M.R.

Oceanological and Hydrobiological Studies

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2010

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Vol. 39, No.2

37-53

EN

We intended to estimate if shallow inshore waters of the Gulf of Gdańsk can be considered important feeding grounds for the fishes under investigation. We also examined whether competition for food exists between the investigated fishes which co-exist. The study was carried out at Sopot and Chałupy stations from summer 2001 to autumn 2003. The results showed the high importance of Neomysis integer, which exclusively lives in coastal waters, in the diet of all three investigated fish species. It indicates that they utilize this zone as a feeding ground. The obtained dataset also led to the conclusion that fish trophic niches overlap by about 40%.

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Does food quality affect the conditions of the sand and common gobies from the Gulf of Gdańsk, Poland?

Waligóra-Borek K., Złoch I., Sapota M. R., Fijałkowska M., Forycka K.

Oceanological and Hydrobiological Studies

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2005

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Vol. 34, No.3

39--55

EN

Sand and common goby specimens were collected from the costal waters in the vicinity of Sopot and Chałupy (Gulf of Gdańsk) from August to October. The relationship between the food consumed and the fish condition was investigated for both species using the Fulton and Clark factors, HSI, feeding intensity, and the index of relative importance. The results indicated that the mean values of the common goby condition factors (20 – 29 mm) were higher in September, the last month of reproduction. The sand gobies (30 – 39 mm) were characterized by lower condition factor values in September, one month after spawning. It was concluded that there is a direct link between diet composition and goby condition during spawning and in the months following it.

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Diel food composition and changes in the diel and seasonal feeding activity of common goby, sand goby and young flounder inhabiting the inshore waters of the Gulf of Gdańsk, Poland

Złoch I., Sapota M., Fijałkowska M.

Oceanological and Hydrobiological Studies

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2005

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Vol. 34, No.3

69--84

EN

A study was conducted from 2001 to 2003 in the Gulf of Gdańsk (Poland) on the diel food composition and diel and seasonal changes in the feeding activity of Pomatoschistus minutus, Pomatoschistus microps, and Platichthys flesus. During the three-year study, no empty fish stomachs were noted, and the fish food was comprised exclusively of prey species that inhabit the shallow water zone (e.g., Bathyporeia pilosa). It can also be stated that the shallow waters of the Gulf of Gdańsk are an important feeding ground for Pomatoschistus sp. and P. flesus. The food intake of all three investigated fish was lower at night than during the day, which led to the conclusion that these fish are day feeders. The seasonal feeding intensity of the sand and common gobies was approximately the same throughout the investigation but was higher in April, June, and August, and lower in September. The flounder fed most intensively in August and March, while feeding intensity was lower in May and June. In September 2001, the most important prey items for P. minutus were Amphipoda undet. and Mysidacea undet. in the morning, N. integer and Mysidacea undet. at noon, and Harpacticoida and Copepoda undet. in the evening. In the same month, P. microps fed mainly on B. pilosa at 08:00, N. integer at 00:00, and Harpacticoida at 20:00. From 2001 to 2003, P. flesus preyed mainly on Polychaeta in the morning hours, while in the evening it targeted N. integer according to the prey frequency of occurrence and quantity in the fish stomachs.