Growth and abundance of Synechococcus sp. in a Mediterranean Bay: Seasonality and relationship with temperature

In this study, we confirm the relationship between temperature and Synechococcus sp. experimental growth rates (r = 0.87, p < 0.005) and provide evidence of the existence of a general relationship. This link leads to a strong seasonality of abundance and biomass of Synechococcus sp. in the Bay of Blanes (NW Mediterranean), which was followed for 2 yr (1995, 1996), with high values in summer months (6 x 10⁷ cells l^-1) and low values in winter (5 x 10⁵ cells l^-1). The growth rate achieved in summer months (1.5 d^-1) is close to or at the maximum possible at the in situ water temperature. As a result, Synechococcus growth may exceed the grazing capacity of its predators in summer, and this explains its significant contribution of > 30 % of the total gross autotrophic production and > 20 % of the total autotrophic biomass in summer. Thus, Synechococcus is an important source of organic C and nutrients for the coastal Mediterranean food web in the summer.