4. The resulting structure—a reef

2014 ◽  
Author(s):  
Charles Sheppard
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Sea Level ◽  
Environmental Conditions ◽  
General Structure ◽  
Back Reef ◽  
Soft Corals ◽  
Basic Pattern ◽  
Geological Time ◽  
Episodic Growth

‘The resulting structure—a reef’ shows that coral reef profiles, composed of reef flats, reef crests, and reef slopes, are remarkably consistent. The general structure is complicated by shifts of sea level over geological time, so the basic pattern will have superimposed upon it evidence of episodic growth and erosion. The environmental conditions on the reef slope are ideal for most corals and other reef life including the soft corals and sponges, so this is where most species are found. The cryptic, or hidden, life of the coral reefs is discussed along with the rugosity of the corals, and the structure and life of the sand in the back reef area.

scholarly journals Measuring Sound at a Cold-Water Coral Reef to Assess the Impact of COVID-19 on Noise Pollution

2021 ◽  
Vol 8 ◽  
Author(s):  
Laurence H. De Clippele ◽  
Denise Risch
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Sea Level ◽  
Cold Water ◽  
Noise Pollution ◽  
Ecosystem Functions ◽  
Noise Levels ◽  
Level Height ◽  
Water Coral

This study compares the noise levels at the cold-water coral Tisler reef, before and after the closure of the border between Norway and Sweden, which occurred as a direct result of the COVID-19 pandemic. The Tisler reef is a marine protected area located under a ferry “highway” that connects Norway and Sweden. Cold-water coral reefs are recognised as being important hotspots of both biodiversity and biomass, they function as breeding and nursing grounds for commercially important fish and are essential in providing ecosystem functions. Whilst studies have shown that fishery, ocean warming, and acidification threaten them, the effects of noise pollution on cold-water coral reefs remains unstudied. To study the severity of noise pollution at the Tisler reef, a long-term acoustic recorder was deployed from 29 January 2020 until 26 May 2020. From 15 March COVID-19 lockdown measures stopped passenger vessel traffic between Norway and Sweden. This study found that the overall noise levels were significantly lower after border closure, due to reduced ferry traffic, wind speeds, and sea level height. When comparing the median hourly noise levels of before vs. after border closure, this study measured a significant reduction in the 63–125 Hz 1/3 octave band noise levels of 8.94 ± 0.88 (MAD) dB during the day (07:00:00–19:59:59) and 1.94 ± 0.11 (MAD) dB during the night (20:00:00–06:59:59). Since there was no ferry traffic during the night, the drop in noise levels at night was likely driven by seasonal changes, i.e., the reduction in wind speed and sea level height when transitioning from winter to spring. Taking into account this seasonal effect, it can be deduced that the COVID-19 border closure reduced the noise levels in the 63–125 Hz 1/3 octave bands at the Tisler reef by 7.0 ± 0.99 (MAD) dB during the day. While the contribution of, and changes in biological, weather-related and geophysical sound sources remain to be assessed in more detail, understanding the extent of anthropogenic noise pollution at the Tisler cold-water coral reef is critical to guide effective management to ensure the long-term health and conservation of its ecosystem functions.

scholarly journals Divergence of seafloor elevation and sea level rise in coral reef ecosystems

2017 ◽  
Vol 14 (6) ◽  
pp. 1739-1772 ◽  
Author(s):  
Kimberly K. Yates ◽  
David G. Zawada ◽  
Nathan A. Smiley ◽  
Ginger Tiling-Range
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Sea Level Rise ◽  
Sea Level ◽  
Anthropogenic Impacts ◽  
Regional Scale ◽  
Coastal Hazards ◽  
Carbonate Production ◽  
Coral Reef Ecosystems ◽  
Study Sites

Abstract. Coral reefs serve as natural barriers that protect adjacent shorelines from coastal hazards such as storms, waves, and erosion. Projections indicate global degradation of coral reefs due to anthropogenic impacts and climate change will cause a transition to net erosion by mid-century. Here, we provide a comprehensive assessment of the combined effect of all of the processes affecting seafloor accretion and erosion by measuring changes in seafloor elevation and volume for five coral reef ecosystems in the Atlantic, Pacific, and Caribbean over the last several decades. Regional-scale mean elevation and volume losses were observed at all five study sites and in 77 % of the 60 individual habitats that we examined across all study sites. Mean seafloor elevation losses for whole coral reef ecosystems in our study ranged from −0.09 to −0.8 m, corresponding to net volume losses ranging from 3.4  ×  106 to 80.5  ×  106 m3 for all study sites. Erosion of both coral-dominated substrate and non-coral substrate suggests that the current rate of carbonate production is no longer sufficient to support net accretion of coral reefs or adjacent habitats. We show that regional-scale loss of seafloor elevation and volume has accelerated the rate of relative sea level rise in these regions. Current water depths have increased to levels not predicted until near the year 2100, placing these ecosystems and nearby communities at elevated and accelerating risk to coastal hazards. Our results set a new baseline for projecting future impacts to coastal communities resulting from degradation of coral reef systems and associated losses of natural and socioeconomic resources.

scholarly journals Exploring coral reef responses to millennial scale climatic forcings: insights from a 1-D numerical tool pyReef-Core v1.0

2018 ◽  
Author(s):  
Tristan Salles ◽  
Jodie Pall ◽  
M. Jody Webster ◽  
Belinda Dechnik
Keyword(s):  
Coral Reef ◽  
Sea Level ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Initial Conditions ◽  
Last Interglacial ◽  
Vertical Growth ◽  
Environmental Processes ◽  
The Impact ◽  
Drill Cores

Abstract. Assemblages of corals characterise specific reef biozones and the environmental conditions that change laterally across a reef and with depth. Drill cores through fossil reefs record the time- and depth-distribution of assemblages, which captures a partial history of the vertical growth response of reefs to changing palaeoenvironmental conditions. The effects of environmental factors on reef growth are well understood on ecological time-scales but are poorly constrained at centennial to millennial timescales. pyReef-Core is a stratigraphic forward model designed to solve the inverse problem of unobservable environmental processes controlling vertical reef development by simulating the physical, biological and sedimentological processes that determine vertical assemblage changes in drill cores. It models the stratigraphic development of coral reefs at centennial to millennial timescales under environmental forcing conditions including accommodation (relative sea level upward growth), oceanic variability (flow speed, nutrients, pH and temperature), sediment input and tectonics. It also simulates competitive coral assemblage interactions using the generalised Lotka-Volterra system of equations (GLVEs) and can be used to infer the influence of environmental conditions on the zonation and vertical accretion and stratigraphic succession of coral assemblages over decadal timescales and greater. The tool can quantitatively test carbonate platform development under the influence of ecological and environmental processes, and efficiently interpret vertical growth and karstification patterns observed in drill cores. We provide two realistic case studies illustrating the basic capabilities of the model and use it to reconstruct (1) the Holocene history (from 8500 years to present) of coral community responses to environmental changes, and (2) the evolution of an idealised coral-reef core since the Last Interglacial (from 140 000 years to present) under the influence of sea-level change, subsidence and karstification. We find that the model reproduces the details of the formation of existing coral-reef stratigraphic sequences both in terms of assemblages succession, accretion rates and depositional thicknesses. It can be applied to estimate the impact of changing environmental conditions on growth rates and patterns under many different settings and initial conditions.

Oceanic δ13C, environmental changes and Carboniferous coral reef development: Records from Tianlin and Ziyun (southern China)

2020 ◽  
Author(s):  
Marine Maillet ◽  
Elias Samankassou
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Southern China ◽  
Ocean Current ◽  
Late Devonian ◽  
Equatorial Position ◽  
Eastern Australia ◽  
Devonian Extinction

<p>Metazoan reef builders receded globally during the Carboniferous, after the Late Devonian extinction event, with only few exceptions of coral-bearing bioconstructions reported worldwide. Among the latter, two exceptional extended coral reefs, dated as Late Viséan–Serpukhovian and Kasimovian-Gzhelian in age, respectively, were recently reported from southern China. The scarcity of coral buildups worldwide suggests global unfavorable conditions, with specific settings considered to represent refugia. To constrain these environmental conditions, seawater composition is reconstructed using carbon and oxygen isotopes originating from five measured sections located in southern China.</p><p>The resulting δ<sup>13</sup>C data reveals several environmental changes throughout the Carboniferous attributed to climate changes, ocean current variations, and proliferation of terrestrial plants. During the Late Viséan-earliest Serpukhovian, the high δ<sup>13</sup>C values (<sub>˜</sub>3‰) are interpreted as recording short-lived glacial events, with the expansion of ice-sheets in South America and eastern Australia. The scarcity of coral reef growth suggests that the cooling acted as an inhibiting factor during this period. Conversely, the development of the exceptional coral reefs in southern China could be explained by the persistence of warm oceanic currents in the epicontinental sea, located in equatorial position. During the Kasimovian-Gzhelian, the gradual δ<sup>13</sup>C positive shift from -0.7 to +4.7‰ coincides with a short-lived warming, which should be suitable for the recovery of coral communities. However, in spite of the mild climate, the scarcity of Pennsylvanian coral reef leads to consider other inhibiting factors (e.g. biological competition and aragonite seas). Interestingly, the disappearance of coral reefs in southern China correlates with negative δ<sup>13</sup>C shifts (e.g. Mid-Viséan, Late Gzhelian), interpreted as related to intensified upwellings.</p><p>The reconstitution of the Carboniferous environmental conditions documents several factors contributing to the metazoan reef demise and recovery subsequent to the Late Devonian extinction events, and adds to our current knowledge of the longest reef recovery in the Phanerozoic.</p><p> </p><p> </p>

scholarly journals Exploring coral reef responses to millennial-scale climatic forcings: insights from the 1-D numerical tool pyReef-Core v1.0

2018 ◽  
Vol 11 (6) ◽  
pp. 2093-2110 ◽  
Author(s):  
Tristan Salles ◽  
Jodie Pall ◽  
Jody M. Webster ◽  
Belinda Dechnik
Keyword(s):  
Coral Reef ◽  
Sea Level ◽  
Environmental Conditions ◽  
Environmental Changes ◽  
Initial Conditions ◽  
Last Interglacial ◽  
Vertical Growth ◽  
Environmental Processes ◽  
The Impact ◽  
Drill Cores

Abstract. Assemblages of corals characterise specific reef biozones and the environmental conditions that change spatially across a reef and with depth. Drill cores through fossil reefs record the time and depth distribution of assemblages, which captures a partial history of the vertical growth response of reefs to changing palaeoenvironmental conditions. The effects of environmental factors on reef growth are well understood on ecological timescales but are poorly constrained at centennial to geological timescales. pyReef-Core is a stratigraphic forward model designed to solve the problem of unobservable environmental processes controlling vertical reef development by simulating the physical, biological and sedimentological processes that determine vertical assemblage changes in drill cores. It models the stratigraphic development of coral reefs at centennial to millennial timescales under environmental forcing conditions including accommodation (relative sea-level upward growth), oceanic variability (flow speed, nutrients, pH and temperature), sediment input and tectonics. It also simulates competitive coral assemblage interactions using the generalised Lotka–Volterra system of equations (GLVEs) and can be used to infer the influence of environmental conditions on the zonation and vertical accretion and stratigraphic succession of coral assemblages over decadal timescales and greater. The tool can quantitatively test carbonate platform development under the influence of ecological and environmental processes and efficiently interpret vertical growth and karstification patterns observed in drill cores. We provide two realistic case studies illustrating the basic capabilities of the model and use it to reconstruct (1) the Holocene history (from 8500 years to present) of coral community responses to environmental changes and (2) the evolution of an idealised coral reef core since the last interglacial (from 140 000 years to present) under the influence of sea-level change, subsidence and karstification. We find that the model reproduces the details of the formation of existing coral reef stratigraphic sequences both in terms of assemblages succession, accretion rates and depositional thicknesses. It can be applied to estimate the impact of changing environmental conditions on growth rates and patterns under many different settings and initial conditions.

Review Lecture - Living corals

1968 ◽  
Vol 169 (1017) ◽  
pp. 329-344 ◽  
Keyword(s):  
Coral Reef ◽  
Calcium Carbonate ◽  
Coral Reefs ◽  
Sea Level ◽  
Living Coral ◽  
Precise Nature ◽  
Functional Aspects

Coral reefs have a dramatic impact owing to their frequent vast extent; above sea level they may form the basis of inhabited islands while below the surface they constitute major hazards to navigation. Perhaps for this reason the precise nature of the animals primarily responsible for their creation tends to be overlooked. Literature on the ‘coral reef problem a matter of primarily geological and geographical concern, is far greater than that on corals themselves. It is as though these animals have become buried under the vast mass of the skeletons they secrete, of the calcium carbonate they extract from the sea to convert into aragonite. Perhaps even the beauty of living coral colonies distracts from consideration of the animal itself. In the hope of in some measure correcting the balance, this lecture is concerned solely with the animal, in particular with the functional aspects of structure together with development and ecology, all viewed from a broadly evolutionary standpoint.

scholarly journals BENTHIC FORAMINIFERA AS BIOINDICATOR OF CORAL REEF ENVIRONMENTAL CONDITION BASED ON FORAM Index IN NATUNA ISLANDS, PROVINCE OF RIAU ISLANDS

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Kinanti Gitaputri ◽  
Hikmat Kasmara ◽  
Hikmat Kasmara ◽  
Hikmat Kasmara ◽  
Tatang S. Erawan ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Environmental Conditions ◽  
Benthic Foraminifera ◽  
Water Environment ◽  
Survey Method ◽  
Weak Correlation ◽  
Coral Coverage ◽  
Simple Index ◽  
Environment Parameters

<p>Foraminifera is one of single-celled protozoa, living in the water environment especially marine waters. This organism can be used as bioindicator of environmental conditions of coral reefs through a simple index called FORAM Index. The purpose of this research are to obtain FORAM Index values​, to know any species of benthic foraminifera bioindicator of coral reefs environmental conditions that have been found and to find out whether there is a relationship between FORAM Index to the condition of coral reefs based on coral coverage percentage. The research used survey method on sediment sampling and measurement of environment parameters by P20 LIPI team in April 2011. Several important steps in this research such as sediment samples preparation, sample observation, and sample identification. The results showed that there were 80 species and 31 genera benthic foraminifera bioindicator of coral reefs environmental conditions were found in the Natuna Islands. The condition of coral reefs in the Natuna Islands based on FORAM Index (FI) values ​​ranged from 2.6 to 5.94, and overall there was a positive relationship between FORAM Index and the condition of coral reefs based on coral coverage percentage i.e., the increase of FI was followed by the increase of coral coverage percentage.  However, in the terms of correlation there were several different results, there was a strong correlation and a weak correlation.</p> <p>Keywords: foraminifera, FORAM index, coral reef.</p>

scholarly journals Climate Change Leads to a Reduction in Symbiotic Derived Cnidarian Biodiversity on Coral Reefs

2021 ◽  
Vol 9 ◽  
Author(s):  
Tamar L. Goulet ◽  
Denis Goulet
Keyword(s):  
Climate Change ◽  
Coral Reef ◽  
Coral Reefs ◽  
Environmental Conditions ◽  
Sea Anemones ◽  
Coral Reef Ecosystem ◽  
Symbiotic Relationships ◽  
Cascade Effect ◽  
Symbiotic Partner ◽  
Reef Ecosystem

Symbiotic relationships enable partners to thrive and survive in habitats where they would either not be as successful, or potentially not exist, without the symbiosis. The coral reef ecosystem, and its immense biodiversity, relies on the symbioses between cnidarians (e.g., scleractinian corals, octocorals, sea anemones, jellyfish) and multiple organisms including dinoflagellate algae (family Symbiodiniaceae), bivalves, crabs, shrimps, and fishes. In this review, we discuss the ramifications of whether coral reef cnidarian symbioses are obligatory, whereby at least one of the partners must be in the symbiosis in order to survive or are facultative. Furthermore, we cover the consequences of cnidarian symbioses exhibiting partner flexibility or fidelity. Fidelity, where a symbiotic partner can only engage in symbiosis with a subset of partners, may be absolute or context dependent. Current literature demonstrates that many cnidarian symbioses are highly obligative and appear to exhibit absolute fidelity. Consequently, for many coral reef cnidarian symbioses, surviving changing environmental conditions will depend on the robustness and potential plasticity of the existing host-symbiont(s) combination. If environmental conditions detrimentally affect even one component of this symbiotic consortium, it may lead to a cascade effect and the collapse of the entire symbiosis. Symbiosis is at the heart of the coral reef ecosystem, its existence, and its high biodiversity. Climate change may cause the demise of some of the cnidarian symbioses, leading to subsequent reduction in biodiversity on coral reefs.

New chromadorid nematodes from Brazilian coral reefs: a taxonomic contribution to Chromadora Bastian, 1865

Zootaxa ◽  
2021 ◽  
Vol 5032 (1) ◽  
pp. 47-79
Author(s):  
PATRÍCIA FERNANDES NERES ◽  
PAULO JORGE PARREIRA DOS SANTOS ◽  
ANDRÉ MORGADO ESTEVES
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Sea Level ◽  
Species Identification ◽  
Benthic Fauna ◽  
Diagnostic Characteristics

A study involving experiments on a natural Brazilian coral reef, with the aim of assessing the impacts that may be caused by an increase in sea level on benthic fauna, showed that Chromadoridae Filipjev, 1917 was the most abundant and diverse family of Nematoda. Our results also showed that Chromadora Bastian, 1865 was the most abundant and diverse genus, represented by three species: C. serrambi sp. nov., C. pernambucana sp. nov. and C. macrolaimoides Steiner, 1915. Chromadora serrambi sp. nov. is the only Chromadora species where pre-cloacal supplements are absent. Chromadora pernambucana sp. nov. is differentiated by gubernaculum shape and by three supplements, of which two are cup-shaped (small and slightly sclerotized) and a pre-cloacal papilla very close to the cloaca. Chromadora macrolaimoides is very similar to specimens described previously. Here, we propose a grouping of species based on features considered to be most relevant for species identification and present it as an illustrated guide. The diagnostic characteristics of all species were considered, and following discussions, C. micropapillata was revalidated. Finally, the most relevant diagnostic characteristics for the differentiation of Chromadora species were highlighted.  

BENTHIC FORAMINIFERA AS BIOINDICATOR OF CORAL REEF ENVIRONMENTAL CONDITION BASED ON FORAM Index IN NATUNA ISLANDS, PROVINCE OF RIAU ISLANDS

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Kinanti Gitaputri ◽  
Hikmat Kasmara ◽  
Hikmat Kasmara ◽  
Hikmat Kasmara ◽  
Tatang S. Erawan ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Environmental Conditions ◽  
Benthic Foraminifera ◽  
Water Environment ◽  
Survey Method ◽  
Weak Correlation ◽  
Coral Coverage ◽  
Simple Index ◽  
Environment Parameters

Foraminifera is one of single-celled protozoa, living in the water environment especially marine waters. This organism can be used as bioindicator of environmental conditions of coral reefs through a simple index called FORAM Index. The purpose of this research are to obtain FORAM Index values​, to know any species of benthic foraminifera bioindicator of coral reefs environmental conditions that have been found and to find out whether there is a relationship between FORAM Index to the condition of coral reefs based on coral coverage percentage. The research used survey method on sediment sampling and measurement of environment parameters by P20 LIPI team in April 2011. Several important steps in this research such as sediment samples preparation, sample observation, and sample identification. The results showed that there were 80 species and 31 genera benthic foraminifera bioindicator of coral reefs environmental conditions were found in the Natuna Islands. The condition of coral reefs in the Natuna Islands based on FORAM Index (FI) values ​​ranged from 2.6 to 5.94, and overall there was a positive relationship between FORAM Index and the condition of coral reefs based on coral coverage percentage i.e., the increase of FI was followed by the increase of coral coverage percentage.  However, in the terms of correlation there were several different results, there was a strong correlation and a weak correlation. Keywords: foraminifera, FORAM index, coral reef.

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