Unexpected abundance: Millepora corals in Late Pleistocene reefs of Egypt

2021 ◽  
Author(s):  
Angelina Ivkić ◽  
Andreas Kroh ◽  
Abbas Mansour ◽  
Martin Zuschin
Keyword(s):  
Coral Reefs ◽  
Red Sea ◽  
Fossil Record ◽  
Habitat Preferences ◽  
Geographic Location ◽  
Scleractinian Corals ◽  
Skeletal Structure ◽  
The World ◽  
Preservation Potential ◽  
Fossil Reef

<p>Coral reefs throughout the world are well known for the dominance of scleractinian corals. However, one group of hydrozoan corals can be very common in modern tropical coral reefs as well: <em>Millepora</em>, the fire coral. The modern Red Sea is particularly well known for its high abundances of <em>Millepora</em>, where the fire coral is dominant on current-exposed reefs. Yet, this hydrozoan has been described as rare in the fossil record throughout the world and the documented abundances in fossil reefs do not match the numbers from modern reefs. The main interpretation to explain this phenomenon so far has been a lower preservation potential of milleporids compared to scleractinians due to differences in skeletal structure.</p><p>During an investigation of six Eemian Egyptian reef sites (29 line intercept transects, typically of 20 m length) we found <em>Millepora</em> in 69% of the fossil reef transects. The abundances were comparable to the adjacent modern reefs (65.13% to 0.26%). Preservation of fossil <em>Millepora</em> was good to excellent and in some cases well-preserved pore characters allowed for identification to species level. Our findings seem to be in stark contrast to results and interpretations of earlier studies, which suggest that <em>Millepora</em> is very rare in the fossil record globally. To understand the reason for this mismatch, we compared the associated scleractinian fauna between fossil reefs with and without <em>Millepora</em> presence. Furthermore, as a differentiation between shallower habitats close to the reef edge and deeper habitats along the reef slope was possible, we were able to investigate habitat preferences. <em>Porites</em> abundances were higher in fossil reefs without <em>Millepora</em>. Based on a comparison with modern communities, this suggests that the exposure to water energy might be a decisive factor for <em>Millepora</em> presence in the fossil reef. Therefore, preservation and consecutive investigation of appropriate fire coral-habitats is a pre-requisite for valid comparisons.</p><p>Another factor for the mismatch between our results and earlier studies might be a difference in diagenetic conditions that allow preservation of hydrozoan skeletons in the fossil record. Preservation of the investigated Egyptian sites is favored by their young geological age and their geographic location in a desert climate, reducing dissolution by aggressive meteoric waters. Furthermore, the extremely high abundance of <em>Millepora</em> in modern Red Sea coral reefs may in part mitigate the lower preservation potential of the hydrozoan skeleton in comparison with that of scleractinian corals.</p>

Staghorn Corals of the World

1999 ◽  
Author(s):  
Carden Wallace
Keyword(s):  
Coral Reefs ◽  
Geographic Location ◽  
General Biology ◽  
Distribution Maps ◽  
Black And White ◽  
Worldwide Distribution ◽  
Full Page ◽  
The World ◽  
Major Review ◽  
Reference Tool

Staghorn corals (genus Acropora) are the most obvious and important corals on coral reefs throughout the world, providing much of the beauty and variety seen on the reefs. This invaluable reference tool is the first major review of Acropora in over 100 years. It assesses all the known species worldwide, describing each in detail and illustrating the range of variability of form with habitat and geographic location. The classification, evolution and worldwide distribution of all species are reviewed and illustrated with colour plates, full page black and white plates and distribution maps. Details of the general biology of staghorn corals are discussed and illustrated.

Molecules, Morphology, Fossils and the Origination and Extinction Dynamics of Scleractinian Corals

2011 ◽  
Vol 17 ◽  
pp. 61-77
Author(s):  
Marcos S. Barbeitos
Keyword(s):  
Coral Reefs ◽  
Fossil Record ◽  
Molecular Phylogenetics ◽  
Evolutionary Dynamics ◽  
Scleractinian Corals ◽  
Future Research ◽  
Marine Biodiversity ◽  
Mass Extinctions ◽  
Extant Species ◽  
The Impact

The history of Scleractinian corals, richly documented by the fossil record, is one of complex dynamics linked to the dynamics of coral reefs themselves. In spite of all the waxing and waning of marine biodiversity throughout the post-Paleozoic, scleractinians have remained remarkably resilient as a lineage and have traversed two mass extinctions and repeated episodes of global change before becoming the chief builders of modern coral reefs. Understanding this history becomes all the more relevant in face of the current human driven coral reef biodiversity crisis. The advent of molecular phylogenetics has changed our perspective of those dynamics because it has uncovered pervasive morphological convergence in traditionally used taxonomic characters, revealing that the current classification is highly artificial. Taxonomy not only obscures important patterns, but also introduces artifacts into estimates of origination and extinction obtained directly from the fossil record. I present a brief review of the impact of molecular phylogenetics on the current understanding of coral evolution, with emphasis on the recently uncovered phyletic link between photosymbiotic, reef dwelling and azooxanthellate, deepwater coral biota. Then, I discuss the role of molecular-based techniques in a future research agenda of the evolutionary dynamics of the order. The greatest challenge for the future is the re-assessment of morphological characters from a cladistic perspective so that extinct and extant species are integrated in a unified phylogenetic framework, allowing rigorous testing of hypotheses on the fascinating biodiversity dynamics of the order.

scholarly journals What Lives in the Ocean? An Introduction to the Biodiversity of the Red Sea

2021 ◽  
Vol 9 ◽  
Author(s):  
Marcelle M. Barreto ◽  
Marcela Herrera ◽  
Manuel Aranda
Keyword(s):  
Coral Reefs ◽  
Red Sea ◽  
Well Being ◽  
Marine Turtles ◽  
The World

Have you ever wondered how many species are out there? Biodiversity refers to all the different plants and animals in the world, and it is incredibly important for our well-being. All organisms have a role in the environment, and healthy ecosystems depend on high biodiversity. For example, tiny plant-like organisms living in the ocean are responsible for most of the oxygen we breathe. Mangroves and coral reefs are homes for many wonderful fish, and they protect our coastlines from storms. The Red Sea is one of the world’s most biodiverse oceans. It is a unique home to many different species that cannot be found anywhere else in the world. Scientists have estimated that there are around 29 species of sharks, 17 of whales and dolphins, 5 of marine turtles, 1,078 of fish, 359 of hard corals, and many more invertebrates. Imagine all the tiny microorganisms that we cannot see!

The Evolutionary Diversity and Ecological Complexity of Coral Reefs

2011 ◽  
Vol 17 ◽  
pp. 111-120 ◽  
Author(s):  
Nancy Knowlton ◽  
Jeremy Jackson
Keyword(s):  
Coral Reefs ◽  
Small Proportion ◽  
Fossil Record ◽  
Marine Species ◽  
Foreseeable Future ◽  
Ecological Complexity ◽  
The Face ◽  
Open Question ◽  
Trophic Linkages ◽  
Bounce Back

Coral reefs are the most biodiverse marine ecosystems on the planet, with at least one quarter of all marine species associated with reefs today. This diversity, which remains very poorly understood, is nevertheless extraordinary when one considers the small proportion of ocean area that is occupied by coral reefs. Networks of competitive and trophic linkages are also exceptionally complex and dense. Reefs have a long fossil record, although extensive reef building comes and goes. In the present, coral reefs sometimes respond dramatically to disturbances, and collapses are not always followed by recoveries. Today, much of this failure to recover appears to stem from the fact that most reefs are chronically stressed by human activities, judging by observations of recovery at exceptional locations where local human activity is minimal. How long reefs can continue to bounce back in the face of warming and acidification remains an open question. Another big uncertainty is how much loss of biodiversity will occur with the inevitable degradation of coral reefs that will continue in most places for the foreseeable future.

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