The examination of native habitats of newly introduced species is one of the factors that can provide information for predicting and preventing invasion success. In this study, we investigated the distribution patterns of a green macroalga, Codium fragile, in its native range in Korea. There were two distinct patterns for Codium spp. within their native habitat. In undisturbed communities, Codium species were members of the understory assemblage below the dominant canopy species. In disturbed habitats where native algae have been harvested for food, the activity created major gaps in the community structure where opportunistic algae expanded their abundance within the community. Codium fragile not only becomes a dominant canopy species in disturbed habitats, but it also colonizes new habitats such as fouling communities. Thus, the distribution patterns of Codium fragile in its native range suggests that it has the capability of taking advantage of disturbed habitats, which may help to explain why it has been such a successful invader in other regions of the world. One interesting finding was the lack of specialized sacoglossan herbivores associated with the Korean populations studied while such herbivores do feed on introduced populations in other regions, and may limit their distribution at some locations.
In this study, a total of 120 fish specimens of common carp (Cyprinus carpio), were caught at four different stations in Shatt Al-Arab (Hareer, Garmat Ali, Al-Maqal and Abual-Khasib). The histological changes in the gills of fish were detected microscopically. Results show that the Shatt Al-Arab is polluted by some different sources of pollutants including power stations, paper industry, oil refineries, petrochemical industry, chemical fertilizer companies and the sewage system and overfishing and the application of pesticides. As a result of these analyses, histopathological changes in the gills of fish specimens, such as hyperplasia, loss of regular shape of secondary lamellae, separation of lamellar epithelium, clavate structure, atrophy of secondary gills lamellae, necrosis, dilation of lamellar capillaries, loss of secondary lamellae, fusion of secondary lamellae, edema, proliferation of cartilage in primary lamellae and curving of primary lamellae, were observed. The histopathological changes in fish gill samples from the Hareer region were much more prevalent than samples caught from other stations.
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