Occurrence And Distribution Of Aquatic Basidiomycetes

Freshwater basidiomycetes have been isolated from foam samples (Jones and Sloof, 1966) and from senescent decaying leaf litter (Nawawi et al., 1977a, 1977b; Marvanova and Stalpers, 1987; Nawawi and Kuthubutheen, 1988), while Stauri-ella aquatica was recovered from test blocks of Dipterocarpus alatus submerged for 9 months in a stream in Khao Yai National Park, Thailand (Sivichai and Jones, 2004). In a study of fungal colonization of senescent palms submerged in a peat swamp at Narathiwat, Thailand, only Ingoldiella hamata was recovered, although other basidiomycetes did occur on fronds in ground contact (Pinruan, 2004; Pinnoi et al., 2006). An aero-aquatic hyphomycete, Peyronelina glomerulata (Fisher et al., 1976; Kane et al., 2002), sporulated on submerged wood after one week's incubation in the laboratory and has been shown to have a basidiomycete teleo-morph (Yamaguchi et al., 2006). Most freshwater basidiomycetes occur as the anamorph stage, with prolific conidial production on leaf material, ensuring wide dispersal and their entrapment to suitable substrata (Read et al., 1992; Jones, 1994). Freshwater basidiomycetes however, are few in number compared to the Ascomycota and anamorphic taxa (Barlocher, 1992; Tsui and Hyde, 2003).

Marine species have been described from wood (Digitatispora lignicola, D. marina, Nia vibrissa) including mangrove (Calathella mangrovei, Haloaleurodis-cus marina), Spartina maritima culm baits (N. globospora), feathers in contact with sand (N. epidermoidea), and as a parasite of the marine angiosperm grass Ruppia maritima (Melanoetenium ruppiae) (see Table 1 for references). Mycaureola dilseae and Melan. ruppiae are unique amongst marine fungi in being host-specific on Dilsea carnosa and R. maritima, respectively (Stanley, 1992; Binder et al., 2006).

Biogeographically marine basidiomycetes are either: (1) restricted to temperate cold water zones, for example D. lignicola, D. marina, M. dilseae (e.g. Henningsson, 1974; Booth, 1983; Koch and Peterson, 1996); (2) restricted to tropical mangrove locations, for example C. mangrovei, Haloc. villosa, Haloc. marina (e.g. Hyde, 1986, 1988; Maekawa et al., 2005; Jones and Puglisi, 2006; Jones et al., 2006); (3) cosmopolitan, for example N. vibrissa (Hyde, 1986; Jones and Vrijmoed, 2003; Jones et al., 2006); (4) known only from their original locations (Rossello et al., 1993; Barata et al., 1997).

Of the 11 marine basidiomycetes, most information is on C. mangrovei, H. villosa and N. vibrissa with Schmidt and Shearer (2003) reporting them from 10, 31 and 20 countries, respectively, and from the Indian, Pacific and Atlantic Oceans, with the exception of C. mangrovei which has not been reported from the latter. Halocyphina villosa has been reported from a wide range of mangrove timbers: 15 in Brunei (Hyde, 1990a), 4 in Singapore but more frequently on Avicennia alba (Leong et al., 1991), 9 on the west coast of India with an average frequency of occurrence of 13.7% (Mari and Sridhar, 2002), 3 on the south west coast of India (Mari and Sridhar, 2003), 3 and more frequently on Nypa. fruticans in the Philippines (Besitulo et al., 2002). In Malaysia, Haloc. villosa and C. mangrovei had a frequency of occurrence of 11.6 (590 collections) and 1.2% (60 collections) respectively (Alias et al., 2007). Halocyphina villosa occurs widely within different geographical locations, for example at six of eight sites in Brunei, and commonly at sites in the Andaman and Nicobar Islands (Hyde, 1988; Chinnaraj, 1993).

Few studies have followed the pattern of basidiomycete colonization of submerged wood. In temperate locations N. vibrissa was recorded on submerged beech test blocks in the UK at Port Erin (24, 36 weeks submergence), Newton Ferrers (16 weeks), D. marina occurred on beech test blocks at Newton Ferrers (32, 40 weeks) while neither were reported on similar test blocks in Langstone Harbour (Byrne and Jones, 1974). On submerged test blocks of four mangrove species, Haloc. villosa occurred frequently on A. alba and A. lanata, but was infrequent on B. cylindrica, and Rh. apiculata (Tan et al., 1989; Leong et al., 1991). H. villosa was present at all stages in the succession on Bruguiera. cylindrica, but occurred only on the intermediate and later stages of the succession on Rh. apiculata (Leong et al., 1991). However, in other studies basidiomycetes have not featured in the colonization of submerged wood (Abdel-Wahab and El-Sharouny, 2002). Physalacria maipoensis may be an early colonizer of senescent Acanthus illicifolius in mangrove habitats (Jones, personal observations). N. vibrissa occurred frequently on timbers of the Tudor ship, The Mary Rose, in the UK, especially when sprayed with chilled water (Jones and Jones, 1993). The occurrence of D. lignicola, D. marina, and M. dilseae may be dictated by low water temperature, that is below 15°C (Jones, 1985, 1986; Stanley, 1992). This may also govern enzyme activity (see below).

Different species have been shown to be vertically distributed on prop roots of Rhizophora apiculata at Morib, Malaysia, Haloc. villosa was the only marine basi-diomycete found and occurred in the upper (1.8-2.2 m) and middle (0.8-1.8 m) zones (Alias, 1996; Alias and Jones, 2000b); while it occurred at all levels in the intertidal zone at Kampong Kapok, Brunei and Ranong mangrove, Thailand (Hyde, 1989, 1990a, 1990b; Hyde et al, 1993). Similarly, Aegerita sp. was observed at three levels on the herbaceous mangrove Avicennia. ilicifolius: basal (directly above soil level), middle (0.5-1.0 m above soil level) and apical (1.5-2.0 m), with frequencies of occurrence of 27.5, 15.0 and 5.0% respectively (Sadaba et al., 1995).

Alias (1996) followed the colonization of submerged test blocks of Avicennia. marina and Bruguiera parviflora at two mangroves in Malaysia and at three different levels (Tables 3 and 4). C. mangrovei and Haloc. villosa were the only bas-idiomycetes recorded. At Kuala Selangor C. mangrovei was an early and intermediate colonizer and was absent in the latter exposure period, while Haloc. villosa was a late colonizer (Table 3). C mangrovei was more frequent on Bruguiera wood while Haloc. villosa showed a preference for Avicennia wood. Both occurred at all levels within the mangrove. At Morib mangrove, C. mangrovei was not collected and Haloc. villosa was an intermediate to late colonizer (Table 4). Examination of drift and attached mangrove showed that Haloc. villosa was common at the three test sites, while C. mangrovei occurred only at Kuala Selangor where the water had a lower salinity and a muddy shore (Table 5).

Sarma and Vittal (2001) recorded the mangrove fungi on different substrata of R. apiculata (seedlings, wood, prop roots) and Avicennia spp. (roots, pneumatoph-ores, wood) in India. H. villosa was the only basidiomycete observed and was present on all the substrata, infrequently on R. apiculata but frequent on Avicennia spp. However, Pasannarai and Sridhar (2001) reported C. mangrovei, H. villosa and N. vibrissa at three, five and four sites, and one, two and two sites in a subsequent study (Pasannarai and Sridhar, 2003) respectively, on the west coast of India. Haloc. villosa was the only species regarded as frequent with a frequency of occurrence of 5.3%. They also observed that all required 6-18 months to sporulate on incubated intertidal wood in the laboratory. Haloc. villosa was listed as very frequent (>10%) in 9 studies out of 41 and frequent in 9 (5-10%) (Sarma and Hyde, 2001).

Freshwater basidiomycetes are primarily known by their anamorphs, which are elaborate and range from sigmoid, tetra-radiate to elaborately branched conidia (Webster, 1992; Marvanova, 1997).

Basidiomycete yeasts have been reported from freshwater lakes, streams, brackish waters to fully saline seawater, sewage contaminated waters and waste-water (Ahearn and Meyers, 1976; Cooke, 1976; Fell, 1976; Pore and Sorenson, 1990). Many marine basidiomycetes have a unicellular budding haploid state alternating with a dikaryotic hyphal state (dimorphic with a yeast state). There are few studies of freshwater basidiomycete yeasts, although extensive data are available on their marine counterparts, obtained from cruises to the Indian, Indo-Pacific and Pacific Oceans, and to the Black and North Seas (Fell, 1976). Table 1 lists selected examples of freshwater and marine basidiomycetous yeasts. That such habitats are rich in yeasts is supported by the unpublished data of Statzell-Tallman and Fell (cited in Kurtzman and Fell, 2006) who reported 23 genera and 120 species (ascomycetes and basidiomycetes) from subtropical Everglade habitats, of which 54% were new taxa to science.

The number of yeasts documented has steadily increased—341 species in 1970, 500 in 1984 and 700 in 1998 (Kurtzman and Fell, 1998), however few of these

Table 3 Frequency of occurrence of marine basidiomycetes on Avicennia marina and Bruguiera parviflora test blocks exposed at Kuala Selangor mangrove, Malaysia

A. marina stand

B. gymnorrhiza stand

Rhizophora apiculata stand

A. marina B. parviflora A. marina B. parviflora A. marina

B. parviflora No. of samples

6-18 weeks

Calathella mangrovei Halocyphina villosa 26-54 weeks C. mangrovei H. villosa 72-90 weeks C. mangrovei H. villosa

4 15

16 16

Source: After Alias (1996).

Note: Dash indicates no fruit bodies detected.

Table 4 Frequency of occurrence of marine basidiomycetes fruiting on Avicennia marina and Bruguiera parviflora test blocks exposed at morib mangrove, Malaysia

6-8 weeks

Calathella mangrovei Halocyphina villosa 26-54 weeks C. mangrovei H. villosa 72-90 weeks C. mangrovei H. villosa

Zone

Zone

Zone

A. marina B. parviflora A. marina B. parviflora A. marina B. parviflora No. of samples

Source: After Alias (1996).

Note: Dash indicates no fruit bodies detected.

Table 5 Frequency of occurrence of Calathella mangrovei and Halocyphina villosa in general collections at three mangroves in Malaysia

Fungus

Kuala Selangor

Port Dickson

Morib

H. villosa

66 (top species)

1 (ranked 56)

44 (ranked 2)

C. mangrovei

9 (ranked 15)

-

-

Source: After Alias (1996).

Source: After Alias (1996).

are aquatic. Marine yeast densities range from 5 to 10 cells per litre (Fell, 1976), and 118-1,228 L"1 (Van Uden and Castello-Branco, 1963) to 3,000 L"1 (Meyers et al., 1967). Many yeasts have been reported from shell fish, food brines and blooms of marine algae, but these remain outside the scope of this chapter. Most are free floating, saprobes of seaweeds and dead marine animals, while others may be animal parasites. Leucospordium spp., Rhodosporidium spp., Candida austromarina (Ascomycota), C. natalensis and Sympodiomyces parvus (Ascomycota) are undoubtedly autochthonous marine species as they are recovered in relatively high cell concentrations from open ocean samples (Fell, 1976; Lachance and Starmer, 1998). They are able to survive for long periods in seawater and can utilize a wide range of carbon compounds (Lachance and Starmer, 1998). However, few yeasts secrete cellulases or chitinases, therefore their contribution to the breakdown of complex organic material is limited (Lachance and Starmer, 1998). While considerable progress has been made in the isolation, identification and phylogenetic studies of aquatic yeasts, there is a singular lack of any detailed investigation of their ecology (Lachance and Starmer, 1998). In fact few microbiological books cover them in any detail, as indeed other aquatic fungi.

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