Biometrical Variation of Posidonia oceanica with Different Bottom Types Along the Entire Turkish Mediterranean Coast

The biometrical dynamics of Posidonia oceanica were studied with regard to variation and its depthwise extension with four major bottom types along the entire Turkish Mediterranean coasts in winter and summer during 2019. The bottom type which mainly consisted of rock, matte (hard bottom), sand, and mud (soft bottom) was a key determinant for biometrical (density and morphometric) changes which were more prominent in summer. The upper and lower limits of vertical depthwise extension of the meadows were restricted by the zonal distribution of the hard bottom. The limits were not restricted on the soft bottom. However, some large areas of the soft bottoms were devoid of the meadows depending on the existence of mobile substrate affected by the high dynamic of water movement. The density variables were higher on hard bottoms than on the soft bottoms; the inter-nodal distance was longer on matte than on rock, sand, and mud, in contrast to leaf biomass. Mud had the lowest number of leaves per shoot and shoot density, whereas rock had the highest number. The shortest rhizome was measured on the rock, while the longest rhizome was measured on matte, which also had the longest leaves. The soft bottoms had wider leaves than the hard bottoms had. Besides the seasonal and depthwise differences in the biometrics, the biometrics were separately assembled between rock and mud. Contrary to the morphometric variables, the density biometrics decreased linearly from the hard bottom to the soft bottom.