Microbial landscapes on the outer tissue surfaces of the reef-building coral Porites compressa

Abstract

Microbial-coral interactions are increasingly recognized as important for coral health and disease. Visualizing these interactions is important for understanding where, when, and how the coral animal and microbes interact. Porites compressa, preserved using Parducz Wxative and examined by scanning electron microscopy, revealed a changing microbial landscape. The external cell layers of this coral were invariably clean of directly adhering microbes, unlike coral-associated mucus. In colonies with expanded polyps, secreted mucus rapidly dissipated, although blobs of new mucus were common; the coral epidermal cells expressed cilia, which are presumably used to clean the surface, and coral-associated microbes were present as Xocs, possibly enmeshed in mucus. In colonies with permanently contracted polyps, the coral epidermis had lost cilia and a stable, multi-lamellar mucous sheet covered the surface of the animal. This sheet became heavily colonized by both prokaryotic and eukaryotic microbes, however these microbes did not penetrate the mucous sheet and the animal's epidermal cell surfaces remained sterile. These observations show that relationships between this coral animal and associated microbes are highly dynamic.

Larvae of Pocillopora damicornis (Anthozoa) settle and metamorphose in response to surface-biofilm bacteria

“…Typically, different bacterial species are found in biofilms and in the nearby planktonic community (Costerton et al 1995, Pasmore & Costerton 2003. For example, the bacterial community in the water column greatly differs from that associated with the surfaces of corals (Johnston & Rohwer 2007) and CCA (Johnson et al 1991). In a harbor, the bacterial community may also differ between biofilms on surfaces and the water column; moreover, 2 bacterial species (particularly Escherichia coli and Vibrio cholerae) were found to be highly dominant on abiotic surfaces in Hawaiian harbors (Shikuma & Hadfield 2010).…”

Coral mucus as an efficient trap for picoplanktonic cyanobacteria: implications for pelagic–benthic coupling in the reef ecosystem

“…Previous studies have determined synechococcoid cyanobacteria to be associated with corals (Rohwer et al Continuous enrichment of pelagic Synechococcus cells via particle trapping in the attached SML remains suggestive, in particular since the mucus released during the first 30 s was discarded during sample collection for this study. Although the SML of corals holds a dynamic microbial community (Johnston & Rohwer 2007), recent studies have reported on the different microbial community composition found in the SML compared to the surrounding seawater (Guppy & Bythell 2006). Ritchie (2006) showed a distinct antibiotic activity regulated by coral mucus and mucus associated bacteria, presumably only allowing for short-term retention of entrapped pelagic cells.…”

Dynamics and impact of the coral disease white plague: insights from a simulation model

“…Other attributes of corals important to disease resistance include mechanical and chemical defenses that vary by species and affect competitive hierarchies (Lang 1973, Nugues & Bak 2006. A better understanding of species-specific defenses to disease is expected from ongoing work into the means by which corals defend against pathogen invasion (Israely et al 2001, Geffen & Rosenberg 2005 and what are 'normal' versus 'diseased' microbial communities of corals (Frias-Lopez et al 2002, Johnston & Rohwer 2007.…”