Cyanobacteria in Coral Reef Ecosystems: A Review

Abstract

<jats:p>Cyanobacteria have dominated marine environments and have been reef builders on Earth for more than three million years (myr). Cyanobacteria still play an essential role in modern coral reef ecosystems by forming a major component of epiphytic, epilithic, and endolithic communities as well as of microbial mats. Cyanobacteria are grazed by reef organisms and also provide nitrogen to the coral reef ecosystems through nitrogen fixation. Recently, new unicellular cyanobacteria that express nitrogenase were found in the open ocean and in coral reef lagoons. Furthermore, cyanobacteria are important in calcification and decalcification. All limestone surfaces have a layer of boring algae in which cyanobacteria often play a dominant role. Cyanobacterial symbioses are abundant in coral reefs; the most common hosts are sponges and ascidians. Cyanobacteria use tactics beyond space occupation to inhibit coral recruitment. Cyanobacteria can also form pathogenic microbial consortia in association with other microbes on living coral tissues, causing coral tissue lysis and death, and considerable declines in coral reefs. In deep lagoons, coccoid cyanobacteria are abundant and are grazed by ciliates, heteroflagellates, and the benthic coral reef community. Cyanobacteria produce metabolites that act as attractants for some species and deterrents for some grazers of the reef communities.</jats:p>

40 Years of benthic community change on the Caribbean reefs of Curaçao and Bonaire: the rise of slimy cyanobacterial mats

“…Several studies describe the occurrence of harmful blooms, particularly of thermo-tolerant species (e.g. Hallock 2005;Paul et al 2005;Paul 2008;Smith and Schindler 2009;Charpy et al 2012). Dense cyanobacterial mats can have a variety of negative effects on reef communities: they inhibit recruitment (Kuffner et al 2006), act as pathogens (Carlton and Richardson 1995), overgrow and smother reef benthos (Ritson-Williams et al 2005;De Bakker et al 2016b), create an anoxic environment (Brocke et al 2015b) and produce chemicals that cause coral and fish mortality (Nagle and Paul 1998).…”

“…Increased occurrence of reef dwelling cyanobacterial blooms has been found on coral reefs around the world (e.g. Charpy et al 2012). It is plausible that a decline in water quality and elevated water temperature initiated the recent shift to dominance of BCM on these reefs (Brocke et al 2015a;Den Haan 2015).…”

Energetic differences between bacterioplankton trophic groups and coral reef resistance

“…Microbial mats dominated by benthic, filamentous species of cyanobacteria also play a large role in coral diseases leading to reef decline (e.g. Black Band Disease); however, the predominant microbial autotrophs in oligotrophic waters surrounding coral reef ecosystems and lagoons are Synecchococcus and Prochlorococcus spp., genera which are not likely to be pathogens in the marine environment [7].…”

Bacterial Biofilm Communities and Coral Larvae Settlement at Different Levels of Anthropogenic Impact in the Spermonde Archipelago, Indonesia

“…Similar most abundant taxa were also among the most abundant on the surfaces of crustose coralline algae, CCA (Sneed et al, 2015). Cyanobacteria, which were found in highest numbers at the inshore site (LL), are often an indicator for bad water quality and eutrophic conditions (Agawina et al, 2003;Paerl et al, 2011) and may inhibit coral recruitment (Charpy et al, 2012), while Alphaproteobacteria, which had the lowest abundance at the inshore site, are often associated with more oligotrophic systems (Yin et al, 2013) and were found to be dominant on CCA surfaces, where their decrease was shown to reduce coral larvae settlement (Webster et al, 2011). These findings corroborate the assumption that the environmental conditions at the inshore site, which was most affected by anthropogenic impacts from nearby Makassar, accommodate a certain BCC accustomed to these conditions.…”