Modeling approach to regime shifts of primary production in shallow coastal ecosystems

Pristine coastal shallow systems are usually dominated by extensive meadows of seagrass species, 14 which are assumed to take advantage of nutrient supply from sediment. An increasing nutrient input is 15 thought to favour phytoplankton, epiphytic microalgae, as well as opportunistic ephemeral macroalgae 16 that coexist with seagrasses. The primary cause of shifts and succession in the macrophyte community 17 is the increase of nutrient load to water; however temperature plays also an important role. A 18 competition model between rooted seagrass (Zostera marina), macroalgae (Ulva sp), and 19 phytoplankton has been developed to analyse the succession of primary producer communities in these 20 systems. Successions of dominance states, with different resilience characteristics, are found when 21 modifying the input of nutrients and the seasonal temperature and light intensity forcing. 22 23