Healthy and diverse coral reefs in Djibouti – A resilient reef system or few anthropogenic threats?

Cowburn, Benjamin; Samoilys, Melita; Osuka, Kennedy; Klaus, Rebecca; Newman, C.M.; Gudka, Mishal; Obura, David

doi:10.1016/j.marpolbul.2019.07.040

Cited by 12 publications

(12 citation statements)

References 67 publications

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Section: Introductionmentioning

confidence: 99%

“…Coral reef ecosystems are a complex interwoven assembly of different species, playing key roles in maintaining marine biodiversity [1,2]. A significant body of research on reef fish and corals has identified the Red Sea as a region of high diversity and endemism [2][3][4]. Coral reefs have been exposed to several stressors during the past years, either due to the massive anthropogenic activities or climate change, at the global scale [5], the Red Sea [1,3], and the Gulf of Aqaba (GoA) ( Figure 1a) [6][7][8][9], which lead to the outbreak of disease in these corals [3,6,10].…”

Section: Introductionmentioning

confidence: 99%

“…Chl a value in the UL never exceeded that of oligotrophic conditions 2. Six outlier points excluded.Previous studies have suggested the importance of introducing water circulation systems to increase water exchange for the purpose of eutrophication management in lagoons[15,18,27].…”

mentioning

confidence: 99%

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Chlorophyll–Nutrient Relationships of an Artificial Inland Lagoon Equipped with Seawater Replenishment System in the Northern Red Sea (Gulf of Aqaba)

Al-Rshaidat

Segonds‐Pichon

Salem³

2020

JMSE

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Data are reported for an inland artificial lagoon (Ayla) to evaluate the impact of the lagoon’s modeled design and water replenishment system on its water quality and the coastal ecosystem. This study focused on Ayla’s upper lagoon (UL) only, due to its isolation from the two other lagoons and the ambient seawater in the Gulf of Aqaba (GoA). Nutrient measurements (nitrite, nitrate, ammonium, phosphate, and silicate) in addition to Chlorophyll a (Chl a) data were collected between July 2012 and June 2013. Chl a values in the UL were not significantly different from ambient seawater in the GoA, and the UL did not show seasonal differences (p = 0.456). Significant variability for nitrite was observed in the UL between spring and summer (p < 0.0001) and between fall and winter (p < 0.0001). Nitrite showed a stronger seasonal effect in the GoA seawater than in the UL (p = 0.056). Phosphorus showed a seasonal effect and remained similar between the UL and GoA. Nutrient stoichiometry showed a Redfield-like nitrogen-to-phosphorus (N:P) ratio for the ambient GoA seawater around the inlet pumping source and an increased N:P ratio inside the UL. This study emphasizes the importance of modeled lagoon design and seawater replenishment system in preventing and inhibiting eutrophication of the lagoon and therefore minimizing contamination in the coastal ecosystem.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chlorophyll–Nutrient Relationships of an Artificial Inland Lagoon Equipped with Seawater Replenishment System in the Northern Red Sea (Gulf of Aqaba)

Al-Rshaidat

Segonds‐Pichon

Salem³

2020

JMSE

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“…In the Red Sea, the genetic differentiation of the southernmost and hottest region suggests that it hosts different populations of species that could be the most warm‐adapted (Figure 2 ). Interestingly, this region also appears to be slightly more genetically and oceanographically (Wang et al, 2019 ) connected to reefs outside the Red Sea (i.e., Djibouti) (Figure 2 ), where no bleaching was observed in 2015 (Cowburn et al, 2019 ). This represents the potential for another insurance policy case with replenishment originating from outside the basin boundary.…”

Section: Bleaching‐recovery‐through‐connectivity Nexus and High Blue Carbon Spotsmentioning

confidence: 99%

A portfolio of climate‐tailored approaches to advance the design of marine protected areas in the Red Sea

Gajdzik

DeCarlo

Aylagas

et al. 2021

Global Change Biology

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Intensified coastal development is compromising the health and functioning of marine ecosystems. A key example of this is the Red Sea, a biodiversity hotspot subjected to increasing local human pressures. While some marine‐protected areas (MPAs) were placed to alleviate these stressors, it is unclear whether these MPAs are managed or enforced, thus providing limited protection. Yet, most importantly, MPAs in the Red Sea were not designed using climate considerations, likely diminishing their effectiveness against global stressors. Here, we propose to tailor the design of MPAs in the Red Sea by integrating approaches to enhance climate change mitigation and adaptation. First, including coral bleaching susceptibility could produce a more resilient network of MPAs by safeguarding reefs from different thermal regions that vary in spatiotemporal bleaching responses, reducing the risk that all protected reefs will bleach simultaneously. Second, preserving the basin‐wide genetic connectivity patterns that are assisted by mesoscale eddies could further ensure recovery of sensitive populations and maintain species potential to adapt to environmental changes. Finally, protecting mangrove forests in the northern and southern Red Sea that act as major carbon sinks could help offset greenhouse gas emissions. If implemented with multinational cooperation and concerted effort among stakeholders, our portfolio of climate‐tailored approaches may help build a network of MPAs in the Red Sea that protects more effectively its coastal resources against escalating coastal development and climate instability. Beyond the Red Sea, we anticipate this study to serve as an example of how to improve the utility of tropical MPAs as climate‐informed conservation tools.

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“…This semi-enclosed sea is subject to Red Sea influence in the North and Indian Ocean in the East ( Youssouf et al ., 2016 ). Located at the junction between the Red Sea and the Gulf of Aden, it hosts a number of endemic species from these two large biogeographical regions (56 coral genera; Youssouf et al ., 2016 ; Cowburn et al ., 2019 ) and is hypothesized to constitute the original source of thermally resistant coral populations, selected for their resistance to the elevated temperatures of the southern Red Sea and currently found in the GoA ( Fine et al ., 2013 ). Summer MMM SST in the GoT is ~30.9°C (1982–2016; Cowburn et al ., 2019 ), which would indicate a predicted bleaching threshold of 31.9°C (MMM + 1°C; sensu Coral Reef Watch), compared to the GoA, with an MMM of 27.1°C (2008–2018; Israel National Monitoring Program) and an experimentally assessed bleaching threshold of ~33°C (MMM + 6°C; Krueger et al ., 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Assessment of temperature optimum signatures of corals at both latitudinal extremes of the Red Sea

Banc-Prandi

Evensen

Barshis

et al. 2022

Conservation Physiology

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Rising ocean temperatures are pushing reef-building corals beyond their temperature optima (Topt), resulting in reduced physiological performances and increased risk of bleaching. Identifying refugia with thermally resistant corals and understanding their thermal adaptation strategy is therefore urgent to guide conservation actions. The Gulf of Aqaba (GoA, northern Red Sea) is considered a climate refuge, hosting corals that may originate from populations selected for thermal resistance in the warmer waters of the Gulf of Tadjoura (GoT, entrance to the Red Sea and 2000 km south of the GoA). To better understand the thermal adaptation strategy of GoA corals, we compared the temperature optima (Topt) of six common reef-building coral species from the GoA and the GoT by measuring oxygen production and consumption rates as well as photophysiological performance (i.e. chlorophyll fluorescence) in response to a short heat stress. Most species displayed similar Topt between the two locations, highlighting an exceptional continuity in their respective physiological performances across such a large latitudinal range, supporting the GoA refuge theory. Stylophora pistillata showed a significantly lower Topt in the GoA, which may suggest an ongoing population-level selection (i.e. adaptation) to the cooler waters of the GoA and subsequent loss of thermal resistance. Interestingly, all Topt were significantly above the local maximum monthly mean seawater temperatures in the GoA (27.1°C) and close or below in the GoT (30.9°C), indicating that GoA corals, unlike those in the GoT, may survive ocean warming in the next few decades. Finally, Acropora muricata and Porites lobata displayed higher photophysiological performance than most species, which may translate to dominance in local reef communities under future thermal scenarios. Overall, this study is the first to compare the Topt of common reef-building coral species over such a latitudinal range and provides insights into their thermal adaptation in the Red Sea.

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Healthy and diverse coral reefs in Djibouti – A resilient reef system or few anthropogenic threats?

Cited by 12 publications

References 67 publications

Chlorophyll–Nutrient Relationships of an Artificial Inland Lagoon Equipped with Seawater Replenishment System in the Northern Red Sea (Gulf of Aqaba)

Chlorophyll–Nutrient Relationships of an Artificial Inland Lagoon Equipped with Seawater Replenishment System in the Northern Red Sea (Gulf of Aqaba)

A portfolio of climate‐tailored approaches to advance the design of marine protected areas in the Red Sea

Assessment of temperature optimum signatures of corals at both latitudinal extremes of the Red Sea

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