Differences in haematology and respiratory system morphology at three neogobiid species

Gill characteristics and the size and number of erythrocytes were observed for three species of goby: Neogobius melanostomus, N. fluviatilis and N. kessleri. While erythrocyte size was similar in all species, N. fluviatilis had a statistically higher erythrocyte count. Significant differences were found in gill apparatus structure, with N. melanostomus having 25% and 50% greater gill contact area than N. kessleri and N. fluviatilis, respectively. Secretory goblet cells, which produce a protective mucous, were also present in highest numbers in N. melanostomus gill tissues. These physiological and morphological differences may be one reason for differences observed in the invasiveness of these three species.