Ecological notes on fungi in Mangrove forests

Abstract

Lists of all marine and terrestrial fungi described from mangrove plants are compiled and relations between these fungi and mangrove forest plants ( Avicennia, Hibiscus, Pluchea, Rhizophora ) are described. Marine ascomycetes, basidiomycetes and deuteromycetes occur on submerged parts of roots (proproots, pneumatophores), stems and branches. Six of thirty-one species appear to be host specific. Most frequent marine species are Lulworthia sp., Metasphaeria australiensis and ‘ Phoma ’ sp. The majority of the forty-four terrestrial fungi described from mangrove trees are parasites on living leaves. High contents of tannin do not protect mangrove plants from decomposition by marine fungi and wood boring animals (shipworms and isopods). Submerged bark and wood of mangroves are deteriorated by higher marine fungi. Wood destruction is of the ‘soft rot’ type. Fewer kinds of fungi occur on bark than on wood; Mycosphaerella pneumatophorae (in Avicennia ) and Keissleriella blepharospora (in Rhizophora ) are exclusively corticolous. Some fungi develop within calcareous layers of shipworm tubes in mangrove roots or branches. Rhizophora forms adventitious roots above injured and fungus-infested root tips. There is a zonation of fungi and other organisms along vertical roots, stems, or branches of mangrove trees. Submerged parts are inhabited by marine fungi, algae, balanids, worms, shipworms, and gribbles. Several species of fungi are usually found together on the submerged part of one root, but no distinct pattern of vertical distribution among the species is evident. Growth of marine and terrestrial fungi overlaps at the high tide line. Organisms above the water include ascomycetes, deuteromycetes, basidiomycetes, and lichens. Horizontal distribution of fungi in a Hawaiian mangrove swamp along a transect from salt to fresh water is described. Marine fungi are absent in the freshwater part. Thus, host specific K. blepharospora occurs only on Rhizophora plants in salt water. Dispersal and geographical distribution of mangrove fungi are discussed. Knowledge of occurrence of marine fungi in the eastern mangrove is almost absent. Some fungi, chiefly host specific ones, have a limited distribution, while omnivorous species are found in mangroves throughout the tropics and sub-tropics. Most mangrove fungi are warm water species.