Localized outbreaks of coral disease on Arabian reefs are linked to extreme temperatures and environmental stressors

Greta S. Aeby; Emily Howells; Thierry M. Work; David Abrego; Gareth J. Williams; Lisa M. Wedding; Jamie M. Caldwell; Monica M Moritsch; John Burt

doi:10.1007/s00338-020-01928-4

USGS · 70214062

Localized outbreaks of coral disease on Arabian reefs are linked to extreme temperatures and environmental stressors

Greta S. Aeby·Emily Howells·Thierry M. Work·David Abrego·Gareth J. Williams·Lisa M. Wedding·Jamie M. Caldwell·Monica M Moritsch·John Burt

View original source ↗Export metadata ↓

Abstract

The Arabian Peninsula borders the hottest reefs in the world, and corals living in these extreme environments can provide insight into the effects of warming on coral health and disease. Here, we examined coral reef health at 17 sites across three regions along the northeastern Arabian Peninsula (Persian Gulf, Strait of Hormuz and Oman Sea) representing a gradient of environmental conditions. The Persian Gulf has extreme seasonal fluctuations in temperature and chronic hypersalinity, whereas the other two regions experience more moderate conditions. Field surveys identified 13 coral diseases including tissue loss diseases of unknown etiology (white syndromes) in Porites, Platygyra , Dipsastraea , Cyphastrea, Acropora and Goniopora ; growth anomalies in Porites, Platygyra and Dipsastraea ; black band disease in Platygyra , Dipsastraea , Acropora, Echinopora and Pavona ; bleached patches in Porites and Goniopora and a disease unique to this region, yellow-banded tissue loss in Porites . The most widespread diseases were Platygyra growth anomalies (52.9% of all surveys), Acropora white syndrome (47.1%) and Porites bleached patches (35.3%). We found a number of diseases not yet reported in this region and found differential disease susceptibility among coral taxa. Disease prevalence was higher on reefs within the Persian Gulf (avg. 2.05%) as compared to reefs within the Strait of Hormuz (0.46%) or Oman Sea (0.25%). A high number of localized disease outbreaks (8 of 17 sites) were found, especially within the Persian Gulf (5 of 8 sites). Across all regions, the majority of variation in disease prevalence (82.2%) was associated with the extreme temperature range experienced by these corals combined with measures of organic pollution and proximity to shore. Thermal stress is known to drive a number of coral diseases, and thus, this region provides a platform to study disease at the edge of corals’ thermal range.

Explore related subjects

Coral Reefs Article

Source-reported bounding extent: 23.765236889758672° to 26.667095801104814° latitude; 51.8115234375° to 56.953125° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Greta S. Aeby, Emily Howells, Thierry M. Work, David Abrego, Gareth J. Williams, Lisa M. Wedding, Jamie M. Caldwell, Monica M Moritsch, John Burt. 2020-04-20. Localized outbreaks of coral disease on Arabian reefs are linked to extreme temperatures and environmental stressors. https://doi.org/10.1007/s00338-020-01928-4

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Effect of land-use change and climate on coral calcification and geochemistry: A 253-year time series from west Maui

Land-use change and climate variability both regulate land-based inputs of sediment and nutrient delivery to coral reefs, yet few records in Hawaii can identify when these land-based inputs began or how they have evolved through time. We present a 253-year (1760–2013) coral core record from Olowalu reef, Maui, spanning pre-colonial settlement through the rise and decline of sugarcane agriculture, water diversion, and modern coastal development. Trace element ratios (e.g., Ba/Ca, Y/Ca, P/Ca, Fe/Ca, Sr/Ca) and coral growth parameters document how watershed disturbance and climate variability have influenced reef conditions. Coral trace element records exhibit coherent variability at annual to decadal timescales consistent with El Niño–Southern Oscillation and Pacific Decadal Oscillation frequencies, suggesting climatic control on runoff and groundwater delivery. Superimposed on this natural variability, Ba/Ca, P/Ca, and Fe/Ca increased by 17–55% from the eighteenth century to the late twentieth century, with the largest increase occurring during the mid-1900s and coinciding with the maximum extent of Maui sugarcane plantations. These shifts indicate prolonged increases in sediment and nutrient inputs to the reef. Coral calcification increased by ~30% prior to ~1970 but declined thereafter, coincident with the peak sugarcane production. The negative correlation between coral calcification rate and terrigenous proxies (e.g., Ba/Ca, Y/Ca, P/Ca, and Fe/Ca) suggests that episodic terrestrial inputs from sugarcane plantations depressed coral calcification. This record provides the first pre-colonial to modern baseline for ridge-to-reef connectivity in Maui and demonstrates that historical land-use change has left a persistent geochemical imprint on the downstream reef ecosystem.

Hawaii↗

USGS2026

Assessment of antibiotic resistance genes in Caribbean corals, including those treated with amoxicillin

The decimation of reefs from stony coral tissue loss disease prompted the use of a topical amoxicillin treatment to prevent coral mortality. Application of this treatment led to concerns about unintentional impacts such as potential alteration of the coral microbiome and possible spread of antibiotic resistance. We used three different methodologies—microbial RNA sequencing, 16S rRNA amplicon surveys, and microbial qPCR array—to assess these concerns and to establish a baseline of antibiotic resistance genes (ARGs) in untreated coral microbes. We conducted microbial RNA sequencing on wild Montastraea cavernosa coral mucus samples collected before and 24 h after amoxicillin application. While diverse antibiotic resistance genes (ARGs) were expressed, no differences in ARG expression were detected after amoxicillin treatment. Additionally, there were no notable changes in the microbial communities between the before and after samples. In a separate experiment, a microbial qPCR array was used to assess differences in ARGs over longer timescales using cores from wild Colpophyllia natans , comparing never-treated corals with ones treated a single time seven months prior and with those treated multiple times seven months and more prior. No clinically relevant ARGs were detected across any samples. A small number of above-detection reads (4 in the never-treated corals, 2 in the once-treated corals, and 0 in the multi-treated corals) may indicate weak amplification of similar environmental (non-anthropogenic) ARGs in the corals. Results indicate that the localized topical application of amoxicillin to prevent mortality of SCTLD-affected corals does not: (1) significantly disrupt microbiomes, (2) increase ARG expression in adjacent tissues of these species within 24 h, nor (3) increase abundance of clinically relevant ARGs over a 7 month time period.

Florida↗

USGS2025

Pathological drivers of coral diseases across the Arabian Peninsula

Increasing trends of coral mortality are a challenge to coral reef management worldwide, and a need exists to identify the causes and pathways involved. Pathology is useful to help decipher potential causes of mortality in animals, because it illuminates agents associated with lesions and gives insights on the nature of how a host responds to said agents. To better understand the nature of threats facing corals in the Arabian Peninsula, we performed gross and microscopic pathology on corals from Saudi Arabia, Qatar, and the United Arab Emirates. Among 321 coral fragments examined from 21 genera, tissue loss was the most common lesion seen in 31% of samples, reflecting its widespread presence on reefs from the Arabian Peninsula. Histologically, 68% of lesions exhibited necrosis, predominantly in the basal body wall and surface body wall. Endolithic filamentous microalgae and sponges, originating from the skeleton, were associated with 57% and 39% of lesions, respectively, and were often linked to necrosis and hyaline membrane formation. Cell-associated microbial aggregates and coccidia were detected mainly in Acropora, Pocillopora , and Porites but were not associated with adverse host response. Notably, 69–100% of fragments showing lesions were female likely reflecting the temporal reproductive life history of corals in the region. Our findings highlight endolithic organisms as major contributors to coral tissue degradation in the Arabian Peninsula. Future studies might focus on drivers of endolithic microalgal and sponge dynamics in the region and their role in coral reef health.

Coral Reefs↗