engleski

First record of vertical rhizome growth in Zostera marina

Increased sediment loads in marine environments are caused by many different anthropogenic activities and more frequent storms due to climate change. Increases in sedimentation leads to increases in turbidity, which reduces penetration of light in the water. Deposited sediment buries the lower parts of the plant including photosynthetic tissues. A plant can respond to burial with vertical or horizontal rhizome elongation. Vertical rhizome growth is interpreted as a mechanism selected to counteract the effects of burial. Vertical rhizome growth has been described in many seagrass species, but no published records exist of vertical rhizome growth in Zostera marina. As a part of the research on effect of sediment relocation proccessess on the seagrass community in the Novigrad Sea, central Croatian Adriatic, seagrass samples were taken in summer, 2011. Novigrad sea is known to be an area with high sediment movement with 3 seagrass species occurring in that area: Zostera noltii, Zostera marina and Cymodocea nodosa. Three replicates of seagrass samples were collected by SCUBA divers at each of 8 different locations on 3 and 4, 5 meter depth. Seagrass analysis included measurement of biomass and morphological characteristics. Vertical rhizomes in Zostera marina were recorded for the first time according to existing literature. Length and width of vertical internodes were measured. At the end of vertical rhizomes there were shoots present growing from the last node. Vertical growth of Zostera marina might be triggered by sediment accumulation which is present in Novigrad sea. Substantial annual sediment movement, due to natural processes, could have stimulated this developmental response in Z. marina growth. Vertical growth enables Z. marina to withstand negative effects of burial more than it would be possible with only a horizontal rhizome growth, and may contribute to the adaptability of Z. marina to increased storm activity and sediment movement as a result of global climate change.

sediment burial ; seagrass ; vertical growth ; vertical rhizome ; Zostera marina

nije evidentirano