Identification of bacteria associated with a disease affecting the marine sponge Ianthella basta in New Britain, Papua New Guinea

Abstract

Ianthella basta marine sponges in Kimbe Bay, west New Britain, Papua New Guinea were affected by a disease, and exhibited high mortality, between 1996 and 2000. These fan-shaped sponges were mottled with brown lesions, rotted tissue and large holes. The decayed tissue was surrounded by brown biofilm that smothered the ostia openings. Since 1996, I. basta suffered its highest mortality at 3 sites within 16-20 km of the shore of west New Britain. No mortality was observed at 3 other locations further from shore (between 27-41 km), nor at 10 sites located more than 41 km from shore outside of Kimbe Bay in deeper waters, nor at the site nearest to shore. Comparison of the carbon source utilization patterns of 99 bacterial isolates from all healthy and diseased sponges revealed 5 species of bacteria specifically present in diseased I. basta. These bacteria were not present in healthy sponge samples. Bacteria isolated from affected sponges and inoculated onto healthy sponges caused disease signs similar to those in field specimens. The 16S rRNA genes from these bacteria were sequenced and found to correspond with 2 species of Bacillus and 3 species of Pseudomonas. The closest relatives of these bacteria based on BLAST searches included many terrestrial pathogens and species that are used as pathogens against insects and fungi in integrated pest control management. The bacteria causing disease in I. basta may thus originate from pesticides applied to agricultural land, predominantly oil palm plantations, in west New Britain. The possibility that these bacteria can pass virulence factors to marine bacteria through horizontal gene transfer needs to be investigated, as this may have unexpected impacts on marine ecosystems.

Sponge white patch disease affecting the Caribbean sponge Amphimedon compressa

“…Sponge diseases have thus far been reported from many geographic regions, including the Great Barrier Reef, the Indo-Pacific, the Mediterranean and the Caribbean (Harvell et al 1999). Sponge diseases that have already been reported include Aplysina red band syndrome (ARBS) (Olson et al 2006), Aplysina black patch syndrome (Webster et al 2008), sponge orange band (SOB) disease of Xestospongia muta (Cowart et al 2006, López-Legentil et al 2010, Angermeier et al 2011), brown lesion necrosis or disease-like syndrome of Ianthella basta (Cervino et al 2006, Luter et al 2010, spongin-boring necrosis of Rhopaloides odorabile (Webster et al 2002) and pustule disease of Ircinia fasciculata and I. variabilis (Maldonado et al 2010). Outbreaks of various sponge diseases have indeed proven to be fatal on several occasions in different localities (Gaino et al 1992, Vacelet et al 1994, Maldonado et al 2010, Cebrian et al 2011.…”

Bacillus insecticides are not acutely harmful to corals and sponges

“…One strain was most closely related to the group containing B. cereus, B. thuringiensis and B. anthracis, while the other was most closely related to B. pumilus (which can be used as a fungicide) (Jacobsen et al 2004). Simultaneous re-infection of I. basta with 5 isolates (both Bacillus strains and 3 additional Pseudomonas strains) resulted in the onset of disease in this sponge species (Cervino et al 2006). This result raised concerns that accidental overspray or runoff contain-ing commercial Bacillus spp.…”

“…are a common component of marine microbial populations (Ivanova et al 1999), toxic spore-forming B. thuringiensis comprise only a small subset of Bacillus reported in the marine environment (Maeda et al 2001). Two Bacillus strains were recently isolated from diseased sponges, Ianthella basta, from reefs off Papua New Guinea (Cervino et al 2006). One strain was most closely related to the group containing B. cereus, B. thuringiensis and B. anthracis, while the other was most closely related to B. pumilus (which can be used as a fungicide) (Jacobsen et al 2004).…”

“…This result raised concerns that accidental overspray or runoff contain-ing commercial Bacillus spp. may contribute to unexplained disease in coral reef invertebrates (Cervino et al 2006).…”

Eco-physiological response of two marine bivalves to acute exposition to commercial Bt-based pesticide

“…Thus, the assessment of procedures for potential Bt impact on non-target marine organisms should be addressed in the context of biodiversity conservation. Many studies have investigated the potential effects of Bt toxins expressed in genetically modified plants and Bt commercial products mainly on non-target terrestrial fauna (Boisvert and Boisvert, 2000;Pouline et al, 2010) while there is little data on effects of marine organisms (Cervino et al, 2006;Eder and Schönbrunner, 2010). Some authors (Boisvert and Boisvert, 2000;Eder and Schönbrunner, 2010) have proposed the idea that accidental overspray or runoff containing commercial Bt could contribute to unexplained diseases in coral reef invertebrates.…”