Response of the microbial community to coral spawning in lagoon and reef flat environments of Hawaii, USA

Abstract

The response of the microbial community to coral spawning was investigated over a period of 18 mo, from January 2006 to July 2007, in reef flat and lagoon environments of a subtropical embayment (Kaneohe Bay, Oahu, Hawaii, USA). The composition of the bacterioplankton community was characterized using terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial small-subunit (SSU) ribosomal RNA genes in parallel with measurements of microbial cell abundances, bacterial production via 3 H-leucine incorporation, and seawater biochemical parameters. We observed a variable bacterioplankton community structure and 2-to 3-fold changes in the cellular abundance of microorganisms, concentrations of chlorophyll a, and rates of bacterial carbon production at both sites during non-spawning conditions. While shifts in the structure of the bacterioplankton community were evident for both environments following coral spawning, microbial abundances and rates of bacterial production remained largely unchanged from pre-spawning levels. Thus, it appeared that only a small fraction of the microbial community responded to the presence of coral-produced organic matter. Differences in the composition of the bacterioplankton community, cellular abundances of microorganisms, and rates of bacterial production were evident between the lagoon and reef flat sites during non-spawning conditions, probably signifying the importance of the surface flow regime for coastal reef microbial communities. Our observations indicate that the Kaneohe Bay microbial community may be more significantly affected by physical mixing processes than by organic matter loading from coral spawning.

Distinguishing between Microbial Habitats Unravels Ecological Complexity in Coral Microbiomes

“…The concentrations of dissolved inorganic nutrients (NH 4 + , NO 3 − plus NO 2 − , NO 2 − , PO 4 3− , and silicate) were measured using a continuous segmented flow system with methods previously described (59), with NO 3 − derived from subtracting the contribution of NO 2 − . NH 4 + was also measured in the field on unfrozen samples using the orthophthaldialdehyde fluorescence method (60, 61).…”

“…Pigment analysis of the phytoplankton community was performed using high-performance liquid chromatography with known standards on extracts from the frozen filters and quantified as described previously (62). Seawater microbial cell counts were measured using flow cytometry (59). …”

Coastal connectivity and spatial subsidy from a microbial perspective

“…In comparison, DOM and POM generation in coral reefs occurs through mucus release or mass spawning events and around 18% of the total organic carbon generated is exported from the reef to oceanic waters (Naumann et al., ). Spawning events can release 0.02 g C/m 2 of egg associated carbon overnight (Apprill & Rappé, ), which stimulates benthic respiration and production and associated microbial driven loss and recycling of nutrients within the coral reef system (Eyre, Glud, & Pattern, ; Glud, Eyre, & Patten, ).…”

Evidence for rapid, tide-related shifts in the microbiome of the coral Coelastrea aspera

“…In other studies, coral bacterial associates (Ceh et al 2012) and bacterio-plankton communities near corals in Kaneohe Bay, Hawaii (Apprill and Rappé 2011), appeared to remain relatively stable before and after coral spawning. Interestingly, in the latter work, slight changes in bacterial load and microbial community composition in the water column were only observed during low tide conditions, leading the authors to conclude that tidal flow and turbulence were likely to be important factors controlling microbial dynamics on coral reefs.…”