Microbial alteration of Bahamian deep‐sea carbonates

Abstract

An analysis of microborings within sediment and hardground samples collected from the Northwest Providence Channel and the western margin of the Little Bahama Bank was conducted to characterize the endolithic assemblage present, to examine the role of microboring organisms in the alteration of deep‐sea carbonates, and to evaluate the palaeoecologic potential of the aphotic microboring assemblage found. Samples examined in this study were collected at depths ranging from 210 to 1450 m. The microboring assemblage was found to contain: (a) filamentous fungal borings of five distinct types, (b) a 1.0 × 2.5 μm vermicular form of fungal or bacterial origin, (c) an 8‐12 μm tubular, branching form of probably fungal origin, (d) a subapically branched form considered to be fungal, (e) a spinate form of uncertain affinity and (f) sponge borings. Three of these forms are known only from the deep‐marine environment; the remainder are also known from shallow‐marine sediments found well within the photic zone. Both carbonate sediments and lithified hardgrounds are highly altered through the activity of endolithic organisms. Infestation of individual skeletal fragments by microborers may be so extensive as to produce heavily bored envelopes resembling those previously reported to occur only under shallow‐marine conditions. Although the geological ranges of these microborings remain to be established, the presence of such an aphotic assemblage, coupled with the absence of photosynthetic algal borings, could provide a valuable tool in palaeoecological studies. Other potential applications include the determination of turbidite sediment sources and the establishment of relative water depths for the formation of hardground surfaces.

Barotolerance of fungi isolated from deep-sea sediments of the Indian Ocean

“…Extensive fungal borings of calcium carbonate sediments have also been described from 210 to 1450 m in Bahamian waters (Zeff & Perkins 1979). Destruction of deep-sea mussel shell by microorganisms having networking filaments broadly resembling chytrids and other fungi has been reported …”

“…trally radiating filaments as observed in our samples These endolithic fungi are geologically important as have been reported in deep-sea mussel shells (Hook & producers of carbonate detritus in the deep sea Golubic 1993). Zeff & Perkins (1979) have illustrated (Tudhope & Risk 1985). However, these boring endothe presence of various morphologically different lithic fungi have not been cultured or identified.…”

“…Borings of calcareous animal shells in the deep sea, putatively by fungi, have been reported, but the fungi involved in this process have not been cultured (Rooney & Perkins 1972, Zeff & Perkins 1979. Two types of fungi, the obligate and facultative marine fungi, occur in the marine environment (Kohlmeyer & Kohlmeyer 1979).…”

Temperate carbonate cycling and water mass properties from intertidal to bathyal depths (Azores)

“…Hoskin et al, 1986;Hassan, 1998;Vogel et al, 1996Vogel et al, , 2000see Wisshak, 2006 for a review) as well as qualitative assessments of bioeroding communities (e.g. Golubic et al, 1975;Zeff and Perkins, 1979;Budd and Perkins, 1980;Wisshak et al, 2005). Light also governs the differential bioerosion rates of the directly illuminated up-facing orientation compared to the shaded down-facing substrates.…”

Fungi in Porites lutea: association with healthy and diseased corals

“…Le Campion-Alsumard et al (1995a) explained this phenomenon of fungal growth and the polyp's defence mechanisms. During their process of penetration of coral skeleton, their role as bioeroding agents has been confirmed (Perkins & Halsey 1971, Zeff & Perkins 1979, Le Campion-Alsumard et al 1995a. In molluscan shells with fungi, 3 times more calcium was leached than in control shells without fungi (Raghukumar et al 1988).…”