Wave and sediment dynamics along a shallow subtidal sandy beach inhabited by modern stromatolites

Eckman, James E.; Andres, Miriam S.; Marinelli, Roberta L.; Bowlin, Emily; Reid, R. Pamela; Aspden, Rebecca J.; Paterson, David M.

doi:10.1111/j.1472-4669.2007.00133.x

Cited by 34 publications

(20 citation statements)

References 26 publications

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“…Metazoans certainly contributed towards the decline of the microbialites (Buatois et al 2014;Mata and Bottjer 2012), particularly the stromatolites, and their exclusion in modern habitats has enabled some microbialites to thrive (Eckman et al 2008). However, the surprising coexistence of clearly layered stromatolites with active burrowing and grazing metazoans ( Fig.…”

Section: Resultsmentioning

confidence: 98%

Coexisting living stromatolites and infaunal metazoans

2016

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Microbialites, bioaccretionary structures formed during the growth and metabolism of microorganisms (principally cyanobacteria) were the dominant lifeform in shallow late-Archean and Proterozoic oceans. During the Cambrian radiation of metazoan life, which began ~540 Mya, microbialite abundance and diversity further declined following a peak in the Mesoproterozoic. Notwithstanding contention, grazing and bioturbation effects of metazoans have been hypothesized as the dominant driver of modern microbialite scarcity. However, this metazoan-microbialite exclusion has not been fully explored in the few extant microbialites. Here we provide further evidence showing that living marine layered microbialites (stromatolites) coexist with a persistent assemblage of benthic macro-invertebrates, as has previously been demonstrated in some thrombolitic (clotted) microbialites. Surprisingly, these metazoans have active habits, such as burrowing, which should be expected to disrupt the layered matrix. As other studies have shown, through a network of burrows, metazoans can exploit local diurnal oxygen refugia within microbialites as well as escape predation. Our results, therefore, add novel evidence in support of the hypotheses that geologically, metazoans are not always incompatible with stromatolites, while ecologically, microbialites may act as micro-refugia for modern metazoans and historically have performed a similar inferred role in past ecosystems.

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Section: Resultsmentioning

confidence: 98%

Coexisting living stromatolites and infaunal metazoans

2016

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“…Shark Bay differs from Highbourne mainly in salinity, containing nearly double the level (66-72 psu, compared with (33-33.5 psu), respectively (Edgecomb et al, 2014). Furthermore, the Highbourne systems are exposed to higher wave energy compared with their Shark Bay counterparts (Eckman et al, 2008), which may also impact diversity.…”

Section: Resultsmentioning

confidence: 99%

Unravelling core microbial metabolisms in the hypersaline microbial mats of Shark Bay using high-throughput metagenomics

et al. 2015

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Modern microbial mats are potential analogues of some of Earth's earliest ecosystems. Excellent examples can be found in Shark Bay, Australia, with mats of various morphologies. To further our understanding of the functional genetic potential of these complex microbial ecosystems, we conducted for the first time shotgun metagenomic analyses. We assembled metagenomic nextgeneration sequencing data to classify the taxonomic and metabolic potential across diverse morphologies of marine mats in Shark Bay. The microbial community across taxonomic classifications using protein-coding and small subunit rRNA genes directly extracted from the metagenomes suggests that three phyla Proteobacteria, Cyanobacteria and Bacteriodetes dominate all marine mats. However, the microbial community structure between Shark Bay and Highbourne Cay (Bahamas) marine systems appears to be distinct from each other. The metabolic potential (based on SEED subsystem classifications) of the Shark Bay and Highbourne Cay microbial communities were also distinct. Shark Bay metagenomes have a metabolic pathway profile consisting of both heterotrophic and photosynthetic pathways, whereas Highbourne Cay appears to be dominated almost exclusively by photosynthetic pathways. Alternative non-rubisco-based carbon metabolism including reductive TCA cycle and 3-hydroxypropionate/4-hydroxybutyrate pathways is highly represented in Shark Bay metagenomes while not represented in Highbourne Cay microbial mats or any other mat forming ecosystems investigated to date. Potentially novel aspects of nitrogen cycling were also observed, as well as putative heavy metal cycling (arsenic, mercury, copper and cadmium). Finally, archaea are highly represented in Shark Bay and may have critical roles in overall ecosystem function in these modern microbial mats.

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“…The shallow subtidal zone is defined as the area below the lowest tide line that experiences disturbance due to wave action, and for many species waves and tidal currents delineate the boundaries they live within (Eckman et al 2008). Some species are not capable of withstanding intense wave action, and can be dislodged or rendered incapable of foraging (Miller et al 2007).…”

Section: Figure 28mentioning

confidence: 99%

Mechanisms of stability of rhodolith beds: sedimentological aspects

Millar¹,

Gagnon²

2018

Mar. Ecol. Prog. Ser.

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Rhodolith beds are highly diverse benthic communities organized around the physical structure and primary productivity of red coralline algae. Despite a worldwide distribution and growing recognition that rhodolith beds are important calcium carbonate (CaCO3) biofactories, little is known of the factors and processes that regulate their structure, function, and stability. One prevalent and largely untested paradigm is that beds develop in environments where water motion is strong enough to prevent burial by sediments.Observations over seven months and three weeks in the centre and near the upper and lower margins of a Newfoundland rhodolith (Lithothamnion glaciale) bed, as well as a laboratory mesocosm experiment with rhodoliths and dominant macrofauna from the bed, were used to characterize, parse, and model spatial and temporal variation in rhodolith sediment load (RSL) and movement among presumably important abiotic and biotic factors. RSL and movement were largely mediated by a few dominant benthic invertebrates. Hydrodynamic forces were insufficient to displace rhodoliths. Daisy brittle stars (Ophiopholis aculeata) and small common sea stars (Asterias rubens) contributed to dislodgement of sediment from rhodoliths. Large green sea urchins (Strongylocentrotus droebachiensis) easily displaced rhodoliths in mesocosms. Results provide the first quantitative demonstration that rhodolith beds need not be exposed to threshold hydrodynamic conditions to avoid burial. Beds can simply occur in areas where burial is unlikely because of low sedimentation rates. In such cases, select resident bioturbators operating simultaneously at different spatial scales (within and outside rhodoliths) appear to suffice to maintain RSL below lethal quantities, contributing to stability of beds.iii ACKNOWLEDGEMENTS

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Wave and sediment dynamics along a shallow subtidal sandy beach inhabited by modern stromatolites

Cited by 34 publications

References 26 publications

Coexisting living stromatolites and infaunal metazoans

Coexisting living stromatolites and infaunal metazoans

Unravelling core microbial metabolisms in the hypersaline microbial mats of Shark Bay using high-throughput metagenomics

Mechanisms of stability of rhodolith beds: sedimentological aspects

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