Bacterial recolonization of deposit‐feeder egesta: In situ regrowth or immigration?

Abstract

The related processes of disturbance, recolonization, and succession can play major roles in structuring communities and in generating spatial heterogeneity. Nonequilibrium processes have been little studied with respect to microbial community dynamics. Here we report experimental efforts to identify the mechanisms of recolonization of egesta employing two intertidal deposit feeders, Balanoglossus aurantiacus and Nereis succinea. Using direct microscopic counts and Biolog plates, we compared the quantitative and qualitative patterns of recovery in egesta isolated from underlying sediments on “latrines” to recolonization in naturally incubated fecal casts. Significant recovery over the 2‐h observation periods was never seen on latrines. Rapid recovery in metabolic potential was observed in the naturally incubated fecal casts of both animal species. Likewise, a rapid numerical recovery was seen in the egesta of N. succinea casts on sediments. In contrast, no numerical recovery was evident in any fecal casts of B. aurantiacus over 2 h, regardless of treatment. For these two species, recolonization appears to be dominated by migration of bacteria from underlying sediments as opposed to repopulation by survivors of ingestion. These findings indicate that renewal of available (digestible) microbial resources to deposit feeders is more rapid than would be predicted if regrowth was the dominant process of recolonization. Furthermore, because recovery time is short relative to the interval between disturbances, deposit feeding is unlikely to play a major role in structuring benthic microbial communities.

Linkage between crustacean zooplankton and aquatic bacteria

“…The presence of bacteria in fecal materials produced by copepods feeding on axenic food also confirmed that enteric bacteria can be passed onto fecal pellets (Tang 2005). On the other hand, a study with deposit-feeders showed that bacterial proliferation on egesta was faster than could be explained by growth alone (Plante & Wilde 2001), indicating that colonization by external bacteria must have also occurred at the same time.…”

Grapsid crabs mediate link between mangrove litter production and estuarine planktonic food chains

“…While microbial processing of whole-leaf litter would also involve the same general changes, only a modest decline in C/N ratio was noted for the litter bag experiment even after >110 d for both Avicennia marina and Rhizophora stylosa leaf litter. Significant microbial colonisation often results from addition of 'seed' bacteria from the gut of deposit-feeders or those present in the environment, or through regrowth of bacteria surviving through the digestive process (Plante et al 1989, Plante & Wilde 2001. Loss of feeding deterrents, such as phenolics, and dissolved organic matter, by leaching, a predominantly physical process, is also expected to be increased.…”

Increase in Alphaproteobacteria in association with a polychaete, Capitella sp. I, in the organically enriched sediment

“…These biological activities have an enormous impact, not only on the reworking of the sediment, but also on the abundance and community structure of microorganisms in the sediment (Dobbs and Guckert, 1988;Steward et al, 1996;Marinelli et al, 2002;Lucas et al, 2003;Papaspyrou et al, 2006). Microbial abundance tends to increase along the inner walls of the burrows (Alongi, 1985;Aller and Aller, 1986;Lucas et al, 2003;Wu et al, 2003;Wada et al, 2006) and around the feces excreted from the animals (Hargrave, 1976;Plante and Wilde, 2001). Various bacteria actively facilitate the decomposition of the organic matter at these sites (Aller et al, 1983;Reichardt, 1988).…”