Pocillopora cryptofauna and their response to host coral mortality

AbstractScleractinian corals are engineers on coral reefs that provide both structural complexity as habitat and sustenance for other reef-associated organisms via the release of organic and inorganic matter. However, coral reefs are facing multiple pressures from climate change and other stressors, which can result in mass coral bleaching and mortality events. Mass mortality of corals results in enhanced release of organic matter, which can cause significant alterations to reef biochemical and recycling processes. There is little known about how long these nutrients are retained within the system, for instance, within the tissues of other benthic organisms. We investigated changes in nitrogen isotopic signatures (δ15N) of macroalgal tissues (a) ~ 1 year after a bleaching event in the Seychelles and (b) ~ 3 months after the peak of a bleaching event in Mo’orea, French Polynesia. In the Seychelles, there was a strong association between absolute loss in both total coral cover and branching coral cover and absolute increase in macroalgal δ15N between 2014 and 2017 (adjusted r2 = 0.79, p = 0.004 and adjusted r2 = 0.86, p = 0.002, respectively). In Mo’orea, a short-term transplant experiment found a significant increase in δ15N in Sargassum mangarevense after specimens were deployed on a reef with high coral mortality for ~ 3 weeks (p < 0.05). We suggest that coral-derived nutrients can be retained within reef nutrient cycles, and that this can affect other reef-associated organisms over both short- and long-term periods, especially opportunistic species such as macroalgae. These species could therefore proliferate on reefs that have experienced mass mortality events, because they have been provided with both space and nutrient subsidies by the death and decay of corals.

Download Full-text

White Syndrome-Affected Corals Have a Distinct Microbiome at Disease Lesion Fronts

Applied and Environmental Microbiology ◽

10.1128/aem.02799-16 ◽

2016 ◽

Vol 83 (2) ◽

Cited By ~ 19

Author(s):

F. Joseph Pollock ◽

Naohisa Wada ◽

Gergely Torda ◽

Bette L. Willis ◽

David G. Bourne

Keyword(s):

Disease Ecology ◽

Tissue Loss ◽

Coral Tissue ◽

Health States ◽

Host Coral ◽

Tissue Samples ◽

Content Type ◽

White Syndrome ◽

Community Profiling

ABSTRACT Coral tissue loss diseases, collectively known as white syndromes (WSs), induce significant mortality on reefs throughout the Indo-Pacific, yet definitive confirmation of WS etiologies remains elusive. In this study, we integrated ecological disease monitoring, bacterial community profiling, in situ visualization of microbe-host interactions, and cellular responses of the host coral through an 18-month repeated-sampling regime. We assert that the observed pathogenesis of WS lesions on acroporid corals at Lizard Island (Great Barrier Reef) is not the result of apoptosis or infection by Vibrio bacteria, ciliates, fungi, cyanobacteria, or helminths. Histological analyses detected helminths, ciliates, fungi, and cyanobacteria in fewer than 25% of WS samples, and helminths and fungi were also observed in 12% of visually healthy samples. The abundances of Vibrio-affiliated sequences (assessed using 16S rRNA amplicon sequencing) did not differ significantly between health states and never exceeded 3.3% of reads in any individual sample. In situ visualization detected Vibrio bacteria only in summer WS lesion samples and revealed no signs of these bacteria in winter disease samples (or any healthy tissue samples), despite continued disease progression year round. However, a 4-fold increase in Rhodobacteraceae-affiliated bacterial sequences at WS lesion fronts suggests that this group of bacteria could play a role in WS pathogenesis and/or serve as a diagnostic criterion for disease differentiation. While the causative agent(s) underlying WSs remains elusive, the microbial and cellular processes identified in this study will help to identify and differentiate visually similar but potentially distinct WS etiologies. IMPORTANCE Over the past decade, a virulent group of coral diseases known as white syndromes have impacted coral reefs throughout the Indian and Pacific Oceans. This article provides a detailed case study of white syndromes to combine disease ecology, high-throughput microbial community profiling, and cellular-scale host-microbe visualization over seasonal time scales. We provide novel insights into the etiology of this devastating disease and reveal new diagnostic criteria that could be used to differentiate visually similar but etiologically distinct forms of white syndrome.

Download Full-text

Rapid coral mortality following unusually calm and hot conditions on Iriomote, Japan

F1000Research ◽

10.12688/f1000research.12660.2 ◽

2018 ◽

Vol 6 ◽

pp. 1728 ◽

Cited By ~ 2

Author(s):

Andrew H Baird ◽

Sally A. Keith ◽

Erika Woolsey ◽

Ryuta Yoshida ◽

Tohru Naruse

Keyword(s):

Water Movement ◽

Sea Surface ◽

Bleaching Event ◽

Coral Mortality ◽

Average Wind Speed ◽

Common Cause ◽

Wind Speeds ◽

Average Wind ◽

The Mean ◽

Low Wind Speeds

Coral bleaching can be induced by many different stressors, however, the most common cause of mass bleaching in the field is higher than average sea surface temperatures (SST). Here, we describe an unusual bleaching event that followed very calm sea conditions combined with higher than average SST. Patterns of mortality differed from typical bleaching in four ways: 1) mortality was very rapid; 2) a different suite of species were most affected; 3) tissue mortality in Acropora spp. was often restricted to the center of the colony; 4) the event occurred early in summer. The two weeks prior to the event included 8 days where the average wind speed was less than 3 ms-1. In addition, SSTs in the weeks preceding and during the event were 1.0-1.5°C higher than the mean for the last 30 years. We hypothesize that this unusual bleaching event was caused by anoxia resulting from a lack of water movement induced by low wind speeds combined with high SST.

Download Full-text

Diverse symbiont bleaching responses are evident from 2-degree heating week bleaching conditions as thermal stress intensifies in coral

Marine and Freshwater Research ◽

10.1071/mf19220 ◽

2020 ◽

Vol 71 (9) ◽

pp. 1149 ◽

Cited By ~ 1

Author(s):

Sarah Gierz ◽

Tracy D. Ainsworth ◽

William Leggat

Keyword(s):

Thermal Stress ◽

Cellular Responses ◽

Stress Exposure ◽

Thermal Threshold ◽

Host Coral ◽

Cellular Processes ◽

Ecological Scale ◽

Bleaching Response ◽

Degree Heating Weeks ◽

Host Tissues

Coral bleaching is the dysfunction of the coral–algal endosymbiosis and is characterised as a loss of Symbiodiniaceae cells from host tissues or the loss of photosynthetic pigments. This breakdown of symbiosis occurs as a result of elevated temperature beyond the organism’s thermal threshold. The thermal tipping points within the symbiosis have not yet been well resolved, and the mechanisms underlying the various cellular processes of the corals bleaching response remain unknown. This study characterised the cellular responses of the symbiont Cladocopium sp. (syn. clade C3) within the host coral Acropora aspera during exposure to thermal stress. Exposure to temperatures between 2 and 3°C below the bleaching threshold, equating to 2-degree heating weeks (DHWs), results in changes to the symbiont cell morphology and cell division rates. Once corals were exposed to 4 DHWs, over 90% of the symbiont cells showed signs of degradation. Although sub-bleaching thermal stress is not sufficient to trigger bleaching alerts at an ecological scale, this stressor substantially affects the coral symbiosis. It is therefore vital that we begin to quantify how sub-bleaching thermal stress affects the fitness of Symbiodiniacea populations, their coral hosts and subsequently reefs worldwide.

Download Full-text

Recent massive coral mortality events in the South China Sea: Was global warming and ENSO variability responsible?

Chemical Geology ◽

10.1016/j.chemgeo.2012.05.028 ◽

2012 ◽

Vol 320-321 ◽

pp. 54-65 ◽

Cited By ~ 15

Author(s):

Kefu Yu ◽

Jian-xin Zhao ◽

Qi Shi ◽

Gilbert J. Price

Keyword(s):

Global Warming ◽

South China Sea ◽

South China ◽

The South China Sea ◽

Coral Mortality ◽

The South ◽

Enso Variability ◽

Massive Coral ◽

China Sea

Download Full-text

Bioeroding sponge assemblages: the importance of substrate availability and sediment

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315418000164 ◽

2018 ◽

Vol 99 (2) ◽

pp. 343-358 ◽

Cited By ~ 3

Author(s):

Joseph Marlow ◽

Christine H.L. Schönberg ◽

Simon K. Davy ◽

Abdul Haris ◽

Jamaluddin Jompa ◽

...

Keyword(s):

Coral Reef ◽

Environmental Factors ◽

Spatial Variation ◽

Environmental Conditions ◽

Sponge Species ◽

Coral Mortality ◽

Substrate Availability ◽

Abiotic Conditions ◽

Assemblage Composition ◽

Reef Health

Despite global deterioration of coral reef health, not all reef-associated organisms are in decline. Bioeroding sponges are thought to be largely resistant to the factors that stress and kill corals, and are increasing in abundance on many reefs. However, there is a paucity of information on how environmental factors influence spatial variation in the distribution of these sponges, and how they might be affected by different stressors. We aimed to identify the factors that explained differences in bioeroding sponge abundance and assemblage composition, and to determine whether bioeroding sponges benefit from the same environmental conditions that can contribute towards coral mortality. Abundance surveys were conducted in the Wakatobi region of Indonesia on reefs characterized by different biotic and abiotic conditions. Bioeroding sponges occupied an average of 8.9% of available dead substrate and variation in abundance and assemblage composition was primarily attributed to differences in the availability of dead substrate. Our results imply that if dead substrate availability increases as a consequence of coral mortality, bioeroding sponge abundance is also likely to increase. However, bioeroding sponge abundance was lowest on a sedimented reef, despite abundant dead substrate. This suggests that not all forms of coral mortality will benefit all bioeroding sponge species, and sediment-degraded reefs are likely to be dominated by a few resilient bioeroding sponge species. Overall, we demonstrate the importance of understanding the drivers of bioeroding sponge abundance and assemblage composition in order to predict possible impacts of different stressors on reefs communities.

Download Full-text

Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai‘i

PeerJ ◽

10.7717/peerj.3355 ◽

2017 ◽

Vol 5 ◽

pp. e3355 ◽

Cited By ~ 15

Author(s):

Ku‘ulei S. Rodgers ◽

Keisha D. Bahr ◽

Paul L. Jokiel ◽

Angela Richards Donà

Keyword(s):

Coral Bleaching ◽

Temperature Increase ◽

Coral Cover ◽

Past Century ◽

Coral Mortality ◽

Spatial And Temporal Patterns ◽

Nature Preserve ◽

Visitor Use ◽

Circulation Velocity ◽

Two Sectors

Drastic increases in global carbon emissions in the past century have led to elevated sea surface temperatures that negatively affect coral reef organisms. Worldwide coral bleaching-related mortality is increasing and data has shown even isolated and protected reefs are vulnerable to the effects of global climate change. In 2014 and 2015, coral reefs in the main Hawaiian Islands (MHI) suffered up to 90% bleaching, with higher than 50% subsequent mortality in some areas. The location and severity of bleaching and mortality was strongly influenced by the spatial and temporal patterns of elevated seawater temperatures. The main objective of this research was to understand the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP), O‘ahu, Hawai‘i to gain a baseline understanding of the physical processes that influence localized bleaching dynamics. Surveys at HBNP in October 2015 and January 2016 revealed extensive bleaching (47%) and high levels of coral mortality (9.8%). Bleaching was highly variable among the four HBNP sectors and ranged from a low of ∼31% in the central bay at Channel (CH) to a high of 57% in the area most frequented by visitors (Keyhole; KH). The highest levels of bleaching occurred in two sectors with different circulation patterns: KH experienced comparatively low circulation velocity and a low temperature increase while Witches Brew (WB) and Backdoors (BD) experienced higher circulation velocity and higher temperature increase. Cumulative mortality was highest at WB (5.0%) and at BD (2.9%) although WB circulation velocity is significantly higher. HBNP is minimally impacted by local factors that can lead to decline such as high fishing pressure or sedimentation although human use is high. Despite the lack of these influences, high coral mortality occurred. Visitor impacts are strikingly different in the two sectors that experienced the highest mortality evidenced by the differences in coral cover associated with visitor use however, coral mortality was similar. These results suggest that elevated temperature was more influential in coral bleaching and the associated mortality than high circulation or visitor use.

Download Full-text