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The Future of Coral Reefs: Research Submitted to ICRS 2020,...
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The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany

A special issue of Oceans (ISSN 2673-1924).

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 76485

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Rupert Ormond

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Guest Editor
Centre for Marine Biodiversity & Biotechnology, Heriot-Watt University, Edinburgh EH14 4AS, UK
Interests: coral reefs; reef fish; sharks; reef fisheries; corals; marine conservation; marine protected areas
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Peter Schupp

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Guest Editor
1. Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, Schleusenstraße 1, 26382 Wilhelmshaven, Germany
2. Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Heerstrasse 231, 26129 Oldenburg, Germany
Interests: coral reproduction and restoration; phase shifts in benthic communities; coral and sponge microbial symbiosis
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Prior to the postponement of the 14th International Coral Reef Symposium (ICRS 2020, https://www.icrs2020.de/), due to be held in Bremen, Germany, arrangements had been made with the journal OCEANS to produce a conference Special Issue, to which conference delegates could submit papers based on their presentations or posters.

While the conference itself has now been postponed until 2021, the organizers (chaired by Professor Christian Wild) and OCEANS have agreed to continue with the publication of a Special Issue in 2020. This is to provide intending delegates who wish with an appropriate outlet for material that they had expected to publish this year. Suitable manuscripts will be published on-line as they are received and approved, thus ensuring publication in 2020 of manuscripts that are received in good time.

The Special Issue will retain the planned name (i.e. “The Future of Coral Reefs: Research Submitted to ICRS 2020”) and continue to reflect the conference themes. In addition, it is anticipated that a sister (Part II) issue will be published soon before the ICRS 2021 virtual, linked to the virtual and actual conference event.

Instructions on how to submit to OCEANS may be found at https://0-www-mdpi-com.brum.beds.ac.uk/journal/oceans/instructions. All submissions will be subject to standard reviewing procedures to ensure reasonable standards of writing and accuracy. OCEANS has no restrictions on the length of manuscripts and hence, short papers based on either conference presentations or posters will be considered. 

Given delays in holding the Conference, the deadline for submission of abstracts for the this Special Issue has been extended to April 30th, 2021. Authors wishing to submit a manuscript to this issue are asked to notify the coordinating editor, Prof. Dr. Rupert Ormond ([email protected]) as soon as practicable, mentioning their conference abstract reference number.

Authors whose first language is not English are encouraged to submit manuscripts, but it is recommended that they have their text checked by a native English speaker or make use of MDPI’s English editing Service (https://0-www-mdpi-com.brum.beds.ac.uk/authors/english).

Sincerely,

Prof. Dr. Rupert Ormond
Prof. Dr. Peter Schupp
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Oceans is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). For published papers prepared for ICRS 2020, the APC will be fully subsidized by MDPI. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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25 pages, 3070 KiB  
Article
The Condition of Four Coral Reefs in Timor-Leste before and after the 2016–2017 Marine Heatwave
by Catherine J. S. Kim, Chris Roelfsema, Sophie Dove and Ove Hoegh-Guldberg
Oceans 2022, 3(2), 147-171; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans3020012 - 08 Apr 2022
Cited by 1 | Viewed by 5728
Abstract
El Niño Southern Oscillation global coral bleaching events are increasing in frequency, yet the severity of mass coral bleaching is not geographically uniform. Based in Timor-Leste, the present project had two major objectives: (1) assess the baseline of reefs and coral health at [...] Read more.
El Niño Southern Oscillation global coral bleaching events are increasing in frequency, yet the severity of mass coral bleaching is not geographically uniform. Based in Timor-Leste, the present project had two major objectives: (1) assess the baseline of reefs and coral health at four sites and (2) explore water quality and climate-related changes in ocean temperatures on these understudied reef systems. The impacts of climate change were surveyed on coral reefs before and after the 2016–2017 global underwater heatwave, (principally by following coral mortality). Temperature loggers were also deployed between surveys, which were compared to Coral Reef Watch (CRW) experimental virtual station sea surface temperature (SST). CRW is an important and widely used tool; however, we found that the remotely sensed SST was significantly warmer (>1 °C) than in situ temperature during the austral summer accruing 5.79-degree heating weeks. In situ temperature showed no accumulation. There were significant differences in coral cover, coral diversity, and nutrient concentrations between sites and depths, as well as a low prevalence of disease recorded in both years. Change in coral cover between surveys was attributed to reef heterogeneity from natural sources and localized anthropogenic impacts. Timor-Leste has both pristine and impacted reefs where coral cover and community composition varied significantly by site. Degradation was indicative of impacts from fishing and gleaning. The comparison of in situ temperature and remotely sensed SST indicated that bleaching stress in Timor-Leste is potentially mitigated by seasonal coastal upwelling during the Northwest monsoon season. As a climate refugium, the immediate conservation priority lies in the mitigation of localized anthropogenic impacts on coral reefs through increasing the management of expanding human-related sedimentation and fishing. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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14 pages, 1146 KiB  
Article
Correlation between Coral Reef Condition and the Diversity and Abundance of Fishes and Sea Urchins on an East African Coral Reef
by Pia Ditzel, Sebastian König, Peter Musembi and Marcell K. Peters
Oceans 2022, 3(1), 1-14; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans3010001 - 04 Jan 2022
Cited by 9 | Viewed by 6562
Abstract
Coral reefs are one of the most diverse marine ecosystems, providing numerous ecosystem services. This present study investigated the relationship between coral reef condition and the diversity and abundance of fishes, on a heavily fished East African coral reef at Gazi Bay, Kenya. [...] Read more.
Coral reefs are one of the most diverse marine ecosystems, providing numerous ecosystem services. This present study investigated the relationship between coral reef condition and the diversity and abundance of fishes, on a heavily fished East African coral reef at Gazi Bay, Kenya. Underwater visual censuses were conducted on thirty 50 × 5 m belt transects to assess the abundance and diversity of fishes. In parallel, a 25-m length of each of the same transects was recorded with photo-quadrats to assess coral community structure and benthic characteristics. For statistical analyses, multi-model inference based on the Akaike Information Criterion was used to evaluate the support for potential predictor variables of coral reef and fish diversity. We found that coral genus richness was negatively correlated with the abundance of macroalgae, whereas coral cover was positively correlated with both the abundance of herbivorous invertebrates (sea urchins) and with fish family richness. Similarly, fish family richness appeared mainly correlated with coral cover and invertebrate abundance, although no correlates of fish abundance could be identified. Coral and fish diversity were very low, but it appears that, contrary to some locations on the same coast, sea urchin abundance was not high enough to be having a negative influence on coral and fish assemblages. Due to increasing threats to coral reefs, it is important to understand the relationship among the components of the coral reef ecosystem on overfished reefs such as that at Gazi Bay. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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13 pages, 4791 KiB  
Article
Investigation into the Presence of Symbiodiniaceae in Antipatharians (Black Corals)
by Erika Gress, Igor Eeckhaut, Mathilde Godefroid, Philippe Dubois, Jonathan Richir and Lucas Terrana
Oceans 2021, 2(4), 772-784; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2040044 - 25 Nov 2021
Cited by 2 | Viewed by 3377
Abstract
Here, we report a new broad approach to investigating the presence and density of Symbiodiniaceae cells in corals of the order Antipatharia subclass Hexacorallia, commonly known as black corals. Antipatharians are understudied ecosystem engineers of shallow (<30 m depth), mesophotic (30–150 m) and [...] Read more.
Here, we report a new broad approach to investigating the presence and density of Symbiodiniaceae cells in corals of the order Antipatharia subclass Hexacorallia, commonly known as black corals. Antipatharians are understudied ecosystem engineers of shallow (<30 m depth), mesophotic (30–150 m) and deep-sea (>200 m) reefs. They provide habitat to numerous organisms, enhancing and supporting coral reef biodiversity globally. Nonetheless, little biological and ecological information exists on antipatharians, including the extent to which global change disturbances are threatening their health. The previous assumption that they were exempted from threats related to the phenomenon known as bleaching was challenged by the recent findings of high densities of dinoflagellates within three antipatharian colonies. Further studies were thus necessary to investigate the broader uniformity of these findings. Here we report results of an integrated methodology combining microscopy and molecular techniques to investigate the presence and estimate the density of Symbiodiniaceae cells within two antipatharians species—Cupressopathes abies and Stichopathes maldivensis—from both shallow and mesophotic reefs of SW Madagascar. We found that Symbiodiniaceae-like cells were present within samples of both species collected from both shallow and mesophotic reefs, although the overall cell density was very low (0–4 cell mm−3). These findings suggest that presence or high abundance of Symbiodiniaceae is not characteristic of all antipatharians, which is relevant considering the bleaching phenomenon affecting other corals. However, the possibility of higher densities of dinoflagellates in other antipatharians or in colonies exposed to higher light irradiance deserves further investigation. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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14 pages, 1638 KiB  
Article
Reef Fish Associations with Natural and Artificial Structures in the Florida Keys
by Kara Noonan, Thomas Fair, Kristiaan Matthee, Kelsey Sox, Kylie Smith and Michael Childress
Oceans 2021, 2(3), 634-647; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2030036 - 08 Sep 2021
Cited by 1 | Viewed by 4320
Abstract
Throughout the Caribbean, coral reefs are transitioning from rugose, coral-dominated communities to flat, soft coral-dominated habitats, triggering declines in biodiversity. To help mitigate these losses, artificial structures have been used to re-create substrate complexity and support reef inhabitants. This study used natural and [...] Read more.
Throughout the Caribbean, coral reefs are transitioning from rugose, coral-dominated communities to flat, soft coral-dominated habitats, triggering declines in biodiversity. To help mitigate these losses, artificial structures have been used to re-create substrate complexity and support reef inhabitants. This study used natural and artificial structures to investigate the factors influencing the use of habitat by reef fish. During 2018 and 2019, divers added artificial structures and monitored the fish assemblages associating with both the artificial structures and naturally occurring corals. Overall, there were more fish on natural structures than on artificial structures. While structure shape did not influence fish use, there was a non-significant trend for increased use of larger structures. Fish observations did not differ across a gradient of shallow, complex reefs to deeper, flatter reefs; however, analyses of feeding guilds revealed clearer patterns: herbivores and omnivores were positively associated with low rugosity reefs where macroalgal abundance was higher, whereas invertivores preferred more rugose reefs. These results suggest that as reefs lose structural complexity, fish communities may become dominated by herbivores and omnivores. It also appears that the addition of artificial structures of the type used here may not mitigate the effects of structure loss on reef fish assemblages. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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13 pages, 6225 KiB  
Article
Reef Structural Complexity Influences Fish Community Metrics on a Remote Oceanic Island: Serranilla Island, Seaflower Biosphere Reserve, Colombia
by Diana Castaño, Diana Morales-de-Anda, Julián Prato, Amílcar Leví Cupul-Magaña, Johanna Paola Echeverry and Adriana Santos-Martínez
Oceans 2021, 2(3), 611-623; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2030034 - 03 Sep 2021
Cited by 1 | Viewed by 4887
Abstract
Serranilla is a protected island of the Seaflower Biosphere Reserve, far from dense human population. These characteristics could help sustain structurally complex coral reefs, often associated with higher biodiversity, abundance, and biomass of reef-associated organisms, including reef fish. However, the multiple threats present [...] Read more.
Serranilla is a protected island of the Seaflower Biosphere Reserve, far from dense human population. These characteristics could help sustain structurally complex coral reefs, often associated with higher biodiversity, abundance, and biomass of reef-associated organisms, including reef fish. However, the multiple threats present in Serranilla, including intense illegal fishing, can impact coral ecosystems generally and also specific key groups, such as the parrotfish, in particular. During the “Seaflower Research Expedition 2017”, we assessed how structural habitat complexity influences reef fish assemblages. In addition, we explored differences in parrotfish species (family: Scaridae) between Serranilla and San Andrés, the most populated island in the Archipelago. On Serranilla, we found that habitat structure, rugosity, and coral cover accounted for up to 66% of variation in reef fish diversity, abundance, and biomass, with values being higher on more complex reefs. Parrotfish species differed between the islands, with larger species supporting higher biomasses at Serranilla, by comparison with San Andrés; however, the abundance, biomass, and lengths of parrotfish species were low in both areas compared with those reported from other protected Caribbean reefs. Our study indicates that despite the evident relationship between structurally complex habitats and reef fish, other threats in Serranilla could be affecting parrotfish populations, such as illegal fishing, a widespread activity in the area. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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28 pages, 6452 KiB  
Article
Cold-Water Coral Reefs in the Langenuen Fjord, Southwestern Norway—A Window into Future Environmental Change
by Katriina Juva, Tina Kutti, Melissa Chierici, Wolf-Christian Dullo and Sascha Flögel
Oceans 2021, 2(3), 583-610; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2030033 - 25 Aug 2021
Cited by 4 | Viewed by 3988
Abstract
Ocean warming and acidification pose serious threats to cold-water corals (CWCs) and the surrounding habitat. Yet, little is known about the role of natural short-term and seasonal environmental variability, which could be pivotal to determine the resilience of CWCs in a changing environment. [...] Read more.
Ocean warming and acidification pose serious threats to cold-water corals (CWCs) and the surrounding habitat. Yet, little is known about the role of natural short-term and seasonal environmental variability, which could be pivotal to determine the resilience of CWCs in a changing environment. Here, we provide continuous observational data of the hydrodynamic regime (recorded using two benthic landers) and point measurements of the carbonate and nutrient systems from five Lophelia pertusa reefs in the Langenuen Fjord, southwestern Norway, from 2016 to 2017. In this fjord setting, we found that over a tidal (<24 h) cycle during winter storms, the variability of measured parameters at CWC depths was comparable to the intra-annual variability, demonstrating that single point measurements are not sufficient for documenting (and monitoring) the biogeochemical conditions at CWC sites. Due to seasonal and diurnal forcing, parts of the reefs experienced temperatures up to 4 °C warmer (i.e., >12 °C) than the mean conditions and high CT concentrations of 20 µmol kg−1 over the suggested threshold for healthy CWC reefs (i.e., >2170 µmol kg−1). Combined with hindcast measurements, our findings indicate that these shallow fjord reefs may act as an early hotspot for ocean warming and acidification. We predict that corals in Langenuen will face seasonally high temperatures (>18 °C) and hypoxic and corrosive conditions within this century. Therefore, these fjord coral communities could forewarn us of the coming consequences of climate change on CWC diversity and function. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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21 pages, 1424 KiB  
Article
The Status of the Coral Reefs of the Jaffna Peninsula (Northern Sri Lanka), with 36 Coral Species New to Sri Lanka Confirmed by DNA Bar-Coding
by Ashani Arulananthan, Venura Herath, Sivashanthini Kuganathan, Anura Upasanta and Akila Harishchandra
Oceans 2021, 2(3), 509-529; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2030029 - 26 Jul 2021
Cited by 10 | Viewed by 7835
Abstract
Sri Lanka, an island nation located off the southeast coast of the Indian sub-continent, has an unappreciated diversity of corals and other reef organisms. In particular, knowledge of the status of coral reefs in its northern region has been limited due to 30 [...] Read more.
Sri Lanka, an island nation located off the southeast coast of the Indian sub-continent, has an unappreciated diversity of corals and other reef organisms. In particular, knowledge of the status of coral reefs in its northern region has been limited due to 30 years of civil war. From March 2017 to August 2018, we carried out baseline surveys at selected sites on the northern coastline of the Jaffna Peninsula and around the four largest islands in Palk Bay. The mean percentage cover of live coral was 49 ± 7.25% along the northern coast and 27 ± 5.3% on the islands. Bleaching events and intense fishing activities have most likely resulted in the occurrence of dead corals at most sites (coral mortality index > 0.33). However, all sites were characterised by high values of diversity (H’ ≥ 2.3) and evenness (E ≥ 0.8). The diversity index increased significantly with increasing coral cover on the northern coast but showed the opposite trend on the island sites. One hundred and thirteen species of scleractinian corals, representing 16 families and 39 genera, were recorded, as well as seven soft coral genera. Thirty-six of the scleractinian coral species were identified for the first time on the island of Sri Lanka. DNA barcoding using the mitochondrial cytochrome oxidase subunit I gene (COI) was employed to secure genetic confirmation of a few difficult-to-distinguish new records: Acropora aspera, Acropora digitifera, Acropora gemmifera, Montipora flabellata, and Echinopora gemmacea. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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12 pages, 1846 KiB  
Article
Shallow-Water Species Diversity of Common Intertidal Zoantharians (Cnidaria: Hexacorallia: Zoantharia) along the Northeastern Coast of Trinidad, Southern Caribbean
by Stanton Belford
Oceans 2021, 2(3), 477-488; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2030027 - 20 Jul 2021
Viewed by 3671
Abstract
Zoantharians are colonial cnidarians commonly found in shallow tropical Caribbean coral reefs, and are known to be globally distributed. Common species in genera Zoanthus and Palythoa occur at Toco, Trinidad, where they are more abundant than their Scleractinia counterparts relative to benthic coverage. [...] Read more.
Zoantharians are colonial cnidarians commonly found in shallow tropical Caribbean coral reefs, and are known to be globally distributed. Common species in genera Zoanthus and Palythoa occur at Toco, Trinidad, where they are more abundant than their Scleractinia counterparts relative to benthic coverage. In this study, distribution, morphological and molecular data were collected to determine species and symbiont identification to provide more insight on zoantharians. The Line Intercept Point (LIT) transect method recorded coverage at three sites: Salybia (SB), Pequelle (PB), and Grande L’Anse (GA) Bays along the northeastern coast. Variations in morphology, such as tentacle count, oral disk color and diameter were collected from colonies in situ. All specimens were zooxanthellate, and molecular and phylogenetic analyses were done by sequencing the cytochrome oxidase subunit I (COI) gene, and the internal transcribed spacer (ITS) region for species and symbiont identification, respectively. Results showed mean Zoantharia percentage cover was 32.4% ± 5.1 (X ± SE) at SB, 51.3% ± 6.5 (PB), and 72.2% ± 6.1 at GA. Zooxanthellate zoantharians were identified as Palythoa caribaeorum, Palythoa grandiflora, Zoanthus pulchellus, and Zoanthus sociatus. Symbiodiniaceae genera were identified as Cladocopium and Symbiodinium in Palythoa and Zoanthus spp., respectively. Although this is the first molecular examination of zoantharians, and their symbionts in Trinidad, more research is needed to identify and document species distribution and symbiont biodiversity to understand their ecology in these dynamic ecosystems. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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14 pages, 2247 KiB  
Article
After the Fall: The Demographic Destiny of a Gorgonian Population Stricken by Catastrophic Mortality
by Simona Ruffaldi Santori, Maria Carla Benedetti, Silvia Cocito, Andrea Peirano, Roberta Cupido, Fabrizio Erra and Giovanni Santangelo
Oceans 2021, 2(2), 337-350; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2020020 - 19 Apr 2021
Cited by 3 | Viewed by 2299
Abstract
In recent years, the frequency of mass mortality events in marine ecosystems has increased, and several populations of benthic organism have been affected, reducing their density and changing their size and age structure. Few details are known about the dynamics of these populations [...] Read more.
In recent years, the frequency of mass mortality events in marine ecosystems has increased, and several populations of benthic organism have been affected, reducing their density and changing their size and age structure. Few details are known about the dynamics of these populations over long time intervals. In late summer of both 1999 and 2003 two drastic mass mortality events, co-occurring with anomalous temperature increases, affected the northwestern Mediterranean rocky coastal communities. Due to these events the Paramuricea clavata population living at the western edge of La Spezia Gulf (Italy) was stricken, and 78% of the colonies died. This population was monitored from 1998 (pre-mortality) until 2013. This paper deals with the photographic sampling of permanent plots carried out in 2013. The findings were compared with those from the previous sampling series. This long-term, non-destructive sampling highlights the demographic trajectory of the octocoral population there after two anomalous mortality events, indicating that some new drop-point between local extinction and complete recovery may be have been reached. Long-term monitoring (including pre-mortality data) could allow evaluating the effects of global climate change on the conservation of impacted populations. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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15 pages, 19200 KiB  
Article
Mapping Sub-Metre 3D Land-Sea Coral Reefscapes Using Superspectral WorldView-3 Satellite Stereoimagery
by Antoine Collin, Mark Andel, David Lecchini and Joachim Claudet
Oceans 2021, 2(2), 315-329; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2020018 - 02 Apr 2021
Cited by 8 | Viewed by 3464
Abstract
Shallow coral reefs ensure a wide portfolio of ecosystem services, from fish provisioning to tourism, that support more than 500 million people worldwide. The protection and sustainable management of these pivotal ecosystems require fine-scale but large-extent mapping of their 3D composition. The sub-metre [...] Read more.
Shallow coral reefs ensure a wide portfolio of ecosystem services, from fish provisioning to tourism, that support more than 500 million people worldwide. The protection and sustainable management of these pivotal ecosystems require fine-scale but large-extent mapping of their 3D composition. The sub-metre spaceborne imagery can neatly produce such an expected product using multispectral stereo-imagery. We built the first 3D land-sea coral reefscape mapping using the 0.3 m superspectral WorldView-3 stereo-imagery. An array of 13 land use/land cover and sea use/sea cover habitats were classified using sea-, ground- and air-truth data. The satellite-derived topography and bathymetry reached vertical accuracies of 1.11 and 0.89 m, respectively. The value added of the eight mid-infrared (MIR) channels specific to the WorldView-3 was quantified using the classification overall accuracy (OA). With no topobathymetry, the best combination included the eight-band optical (visible + near-infrared) and the MIR8, which boosted the basic blue-green-red OA by 9.58%. The classes that most benefited from this MIR information were the land use “roof” and land cover “soil” classes. The addition of the satellite-derived topobathymetry to the optical+MIR1 produced the best full combination, increasing the basic OA by 9.73%, and reinforcing the “roof” and “soil” distinction. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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13 pages, 62652 KiB  
Article
Severe Heat Stress Resulted in High Coral Mortality on Maldivian Reefs following the 2015–2016 El Niño Event
by Pia Bessell-Browne, Hannah E. Epstein, Nora Hall, Patrick Buerger and Kathryn Berry
Oceans 2021, 2(1), 233-245; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2010014 - 03 Mar 2021
Cited by 4 | Viewed by 3659
Abstract
Coral cover worldwide has been declining due to heat stress caused by climate change. Here we report the impacts of the 2015–2016 El Niño mass coral bleaching event on the coral cover of reefs located on central and northern atolls of the Maldives. [...] Read more.
Coral cover worldwide has been declining due to heat stress caused by climate change. Here we report the impacts of the 2015–2016 El Niño mass coral bleaching event on the coral cover of reefs located on central and northern atolls of the Maldives. We surveyed six reef sites in the Alifu Alifu (Ari) and Baa (South Maalhosmadulu) Atolls using replicate 20 m benthic photo transects at two depths per reef site. Live and recently dead coral cover identified from images differed between reef sites and depth. Recently dead corals on average made up 33% of the coral assemblage at shallow sites and 24% at deep sites. This mortality was significantly lower in massive corals than in branching corals, reaching an average of only 6% compared to 41%, respectively. The best predictors of live coral cover were depth and morphology, with a greater percentage of live coral at deep sites and in massive corals. The same predictors best described the prevalence of recently dead coral, but showed inverse trends to live coral. However, there was high variability among reef sites, which could be attributed to additional local stressors. Coral bleaching and resulting coral mortalities, such as the ones reported here, are of particular concern for small island nations like the Maldives, which are reliant on coral reefs. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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22 pages, 2208 KiB  
Article
An Experimental Approach to Assessing the Roles of Magnesium, Calcium, and Carbonate Ratios in Marine Carbonates
by Claire E. Reymond and Sönke Hohn
Oceans 2021, 2(1), 193-214; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans2010012 - 03 Mar 2021
Cited by 5 | Viewed by 3588
Abstract
Marine biomineralization is a globally important biological and geochemical process. Understanding the mechanisms controlling the precipitation of calcium carbonate [CaCO3] within the calcifying fluid of marine organisms, such as corals, crustose coralline algae, and foraminifera, presents one of the most elusive, [...] Read more.
Marine biomineralization is a globally important biological and geochemical process. Understanding the mechanisms controlling the precipitation of calcium carbonate [CaCO3] within the calcifying fluid of marine organisms, such as corals, crustose coralline algae, and foraminifera, presents one of the most elusive, yet relevant areas of biomineralization research, due to the often-impenetrable ability to measure the process in situ. The precipitation of CaCO3 is assumed to be largely controlled by the saturation state [Ω] of the extracellular calcifying fluid. In this study, we mimicked the typical pH and Ω known for the calcifying fluid in corals, while varying the magnesium, calcium, and carbonate concentrations in six chemo-static growth experiments, thereby mimicking various dissolved inorganic carbon concentration mechanisms and ionic movement into the extracellular calcifying fluid. Reduced mineralization and varied CaCO3 morphologies highlight the inhibiting effect of magnesium regardless of pH and Ω and suggests the importance of strong magnesium removal or calcium concentration mechanisms. In respect to ocean acidification studies, this could allow an explanation for why specific marine calcifiers respond differently to lower saturation states. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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22 pages, 1337 KiB  
Article
Effect of Acute Seawater Temperature Increase on the Survival of a Fish Ectoparasite
by Mary O. Shodipo, Berilin Duong, Alexia Graba-Landry, Alexandra S. Grutter and Paul C. Sikkel
Oceans 2020, 1(4), 215-236; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans1040016 - 04 Oct 2020
Cited by 10 | Viewed by 4136
Abstract
Extreme warming events that contribute to mass coral bleaching are occurring with increasing regularity, raising questions about their effect on coral reef ecological interactions. However, the effects of such events on parasite-host interactions are largely ignored. Gnathiid isopods are common, highly mobile, external [...] Read more.
Extreme warming events that contribute to mass coral bleaching are occurring with increasing regularity, raising questions about their effect on coral reef ecological interactions. However, the effects of such events on parasite-host interactions are largely ignored. Gnathiid isopods are common, highly mobile, external parasites of coral reef fishes, that feed on blood during the juvenile stage. They have direct and indirect impacts on their fish hosts, and are the major food source for cleaner fishes. However, how these interactions might be impacted by increased temperatures is unknown. We examined the effects of acute temperature increases, similar to those observed during mass bleaching events, on survivorship of gnathiid isopod juveniles. Laboratory experiments were conducted using individuals from one species (Gnathia aureamaculosa) from the Great Barrier Reef (GBR), and multiple unknown species from the central Philippines. Fed and unfed GBR gnathiids were held in temperature treatments of 29 °C to 32 °C and fed Philippines gnathiids were held at 28 °C to 36 °C. Gnathiids from both locations showed rapid mortality when held in temperatures 2 °C to 3 °C above average seasonal sea surface temperature (32 °C). This suggests environmental changes in temperature can influence gnathiid survival, which could have significant ecological consequences for host-parasite-cleaner fish interactions during increased temperature events. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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9 pages, 9166 KiB  
Article
Molecular Phylogenetics of Trapezia Crabs in the Central Mexican Pacific
by Hazel M. Canizales-Flores, Alma P. Rodríguez-Troncoso, Eric Bautista-Guerrero and Amílcar L. Cupul-Magaña
Oceans 2020, 1(3), 156-164; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans1030011 - 26 Aug 2020
Viewed by 4556
Abstract
To date, Trapezia spp. crabs have been considered obligate symbionts of pocilloporid corals. They protect their coral hosts from predators and are essential for the health of certain coral species. However, the basic details of this group of crustaceans are lacking, and there [...] Read more.
To date, Trapezia spp. crabs have been considered obligate symbionts of pocilloporid corals. They protect their coral hosts from predators and are essential for the health of certain coral species. However, the basic details of this group of crustaceans are lacking, and there is a need for species-level molecular markers. The Tropical Eastern Pacific (TEP) region harbors important coral communities mainly built by corals of the genus Pocillopora, with three known Trapezia species known to associate with them: Trapezia bidentata, T. formosa and T. corallina. Both taxonomic and molecular analyses were carried out with samples of all three crab species collected from Pocillopora spp. in the Central Mexican Pacific. Analysis of both a mitochondrial and a nuclear gene revealed only two species, T. corallina and T. bidentata. T. formosa however appears to be a morphotype of T. bidentata. The use of integrative taxonomy for this group has increased the knowledge of the biodiversity not only of the study area, but of the whole TEP and will enhance the future study of the Trapezia–Pocillopora symbiosis. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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Review

Jump to: Research, Other

16 pages, 2286 KiB  
Review
A Review of Current and New Optical Techniques for Coral Monitoring
by Jonathan Teague, David A. Megson-Smith, Michael J. Allen, John C.C. Day and Thomas B. Scott
Oceans 2022, 3(1), 30-45; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans3010003 - 20 Jan 2022
Cited by 13 | Viewed by 5106
Abstract
Monitoring the health of coral reefs is essential to understanding the damaging impacts of anthropogenic climate change as such non-invasive methods to survey coral reefs are the most desirable. Optics-based surveys, ranging from simple photography to multispectral satellite imaging are well established. Herein, [...] Read more.
Monitoring the health of coral reefs is essential to understanding the damaging impacts of anthropogenic climate change as such non-invasive methods to survey coral reefs are the most desirable. Optics-based surveys, ranging from simple photography to multispectral satellite imaging are well established. Herein, we review these techniques, focusing on their value for coral monitoring and health diagnosis. The techniques are broadly separated by the primary method in which data are collected: by divers and/or robots directly within the environment or by remote sensing where data are captured above the water’s surface by planes, drones, or satellites. The review outlines a new emerging technology, low-cost hyperspectral imagery, which is capable of simultaneously producing hyperspectral and photogrammetric outputs, thereby providing integrated information of the reef structure and physiology in a single data capture. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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Other

Jump to: Research, Review

7 pages, 3084 KiB  
Brief Report
The Effects of the UV-Blocker Oxybenzone (Benzophenone-3) on Planulae Swimming and Metamorphosis of the Scyphozoans Cassiopea xamachana and Cassiopea frondosa
by William K. Fitt and Dietrich K. Hofmann
Oceans 2020, 1(4), 174-180; https://0-doi-org.brum.beds.ac.uk/10.3390/oceans1040013 - 24 Sep 2020
Cited by 11 | Viewed by 5449
Abstract
Benzophenones are UV-blockers found in most common sunscreens. The ability of Scyphozoan planula larvae of Cassiopea xamachana and C. frondosa to swim and complete metamorphosis in concentrations 0–228 µg/L benzophenone-3 (oxybenzone) was tested. Planulae of both species swam in erratic patterns, 25–30% slower, [...] Read more.
Benzophenones are UV-blockers found in most common sunscreens. The ability of Scyphozoan planula larvae of Cassiopea xamachana and C. frondosa to swim and complete metamorphosis in concentrations 0–228 µg/L benzophenone-3 (oxybenzone) was tested. Planulae of both species swam in erratic patterns, 25–30% slower, and experienced significant death (p < 0.05) in the highest concentrations of oxybenzone tested, whereas the larvae exhibited normal swimming patterns and no death in ≤2.28 µg/L oxybenzone. In addition, metamorphosis decreased 10–30% over 3 days for both species maintained in 228 µg/L oxybenzone. These effects do not involve symbiotic dinoflagellates, as planulae larvae of Cassiopea sp. are aposymbiotic. It is concluded that oxybenzone can have a detrimental impact on these jellyfish. Full article
(This article belongs to the Special Issue The Future of Coral Reefs: Research Submitted to ICRS 2020, Bremen, Germany)
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