Form and functioning of micro size Australian intermittent closed open lake lagoons (ICOLLs) in NSW

ICOLLs are considered to be one of the most ecologically productive ecosystems on earth. Similar to other coastal water bodies, ICOLLs lie at the interface of marine, freshwater and terrestrial systems and therefore represent highly dynamic transition zones between river/creek catchments and near-shore coastal waters. ICOLLs often act as net sinks of land derived sediments and nutrients; mature systems are believed to act as a source of organic material and nutrients to the adjacent sea. Suzuki et al., (1998) describes ICOLLs as having unique structural and functional characteristics as a consequence of their position in the landscape, thus having large spatial and temporal variability in their environmental and (consequently their dependant) biological variables. The focus for this chapter is micro size ICOLLs, classified as any coastal water body that has: (i) the presence of barrier beach, spit or series of barrier islands that can restrict oceanic exchange; (ii) a surface water area of less than 0.5 km2 (iii) the retention of all or the majority of the water mass within the lagoon during low tide in the adjacent sea; and (iv) the capacity of to remain brackish to fully saline either by percolation through and/or overtopping through inlet/outlet channels.