scholarly journals Impacts of heat stress and storm events on the benthic communities of Kenting National Park (Taiwan)

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11744
Author(s):  
Lauriane Ribas-Deulofeu ◽  
Vianney Denis ◽  
Pierre-Alexandre Château ◽  
Chaolun Allen Chen

Over the past few decades, extreme events—such as ocean warming, typhoons, and coral bleaching—have been increasing in intensity and frequency, threatening coral reefs from the physiological to ecosystem level. In the present study, the impacts of rising seawater temperatures, typhoons, and coral bleaching events on benthic communities were seasonally assessed over a 21 month-period, using photo-transects at 11 sites in Kenting National Park (KNP), Taiwan. Between August 2015 and April 2017, seven typhoon events were recorded and in situ seawater temperatures in KNP reached a maximum of 31.2 °C, as opposed to an average maximum SST of 28.8 °C (2007–2016). The state and response of benthic communities to these events were interpreted based on the environmental conditions of KNP. The repeated storms lowered the levels of thermal stress during the 2015–2016 El Niño event and may have mitigated its impact on the Taiwanese coral reefs. However, storm-induced local shifts from coral to macro-algae dominance were observed. Storms may mitigate the negative effects of heatwaves, but the mechanical damage induced by the storms may also decrease the structural complexity of reefs and their associated diversity. Eventually, despite reef persistence, the composition and function of remnant communities may profoundly diverge from those in regions with less active storms.

2021 ◽  
Vol 8 ◽  
Author(s):  
Julia Biscaia Zamoner ◽  
Anaide Wrublevski Aued ◽  
Luis Carlos Pinto Macedo-Soares ◽  
Vitor André Passos Picolotto ◽  
Carlos Alberto Eiras Garcia ◽  
...  

Reefs are the richest marine ecosystems. Their benthic communities generate structural complexity and participate in nutrient cycles, providing habitat and food for many marine species. These ecosystems have been threatened by local and global anthropogenic impacts and changes in community structure have led to loss of biodiversity, ecosystem function and services worldwide. Most studies about these structural changes have been conducted in Caribbean and Indo-Pacific coral reefs. In the Southwestern Atlantic, where reefs are naturally algae-dominated, these efforts are incipient, especially at oceanic islands where local anthropic impacts tend to be lower, and natural and climate-induced fluctuations might be easily detected. We conducted the first temporal assessment of benthic communities and the influence of oceanographic parameters between 2013 and 2019 in Fernando de Noronha (FNA), the largest Brazilian oceanic archipelago. We annually sampled benthic communities in FNA’s shallow reefs (2–21 m) using photoquadrats, quantified and gathered organisms in major groups according to their functional roles. We also characterized and tested “sea surface temperature,” “marine heatwaves,” “diffuse attenuation coefficient,” and “wave energy” influence for the same period. The most abundant groups were epilithic algal matrix (EAM; mean annual coverage: 23–60%), macroalgae (15–35%) and calcifiers (15–29%), followed by cyanobacteria (1–37%), suspension/filter-feeders (<2%), zoanthids (<1%) and other invertebrates (<0.1%). EAM was negatively correlated with “marine heatwaves” and positively correlated with “wave energy,” while macroalgae and calcifiers showed opposite responses to “marine heatwaves” and “wave energy,” respectively. Cyanobacteria was positively correlated with “marine heatwaves.” The dominance of EAM and macroalgae was already described for reefs along the Brazilian Province and we demonstrated the persistence of this structure over the years in FNA, with the exception of 2019 when there was a substantial increase of cyanobacteria after a strong marine heatwave. Our results suggest a flickering dynamic between EAM and macroalgae, which vary according to the oceanographic conditions, reinforcing its distinct dynamics from most tropical coral reefs. However, the increase of cyanobacteria added to projections of more frequent and stronger marine heatwaves worldwide indicate possible structural changes in this community. Continued monitoring of community and oceanographic drivers is key for better understanding and predicting changes in important marginal reefs.


2019 ◽  
Vol 7 (11) ◽  
pp. 388 ◽  
Author(s):  
Shashank Keshavmurthy ◽  
Chao-Yang Kuo ◽  
Ya-Yi Huang ◽  
Rodrigo Carballo-Bolaños ◽  
Pei-Jei Meng ◽  
...  

Coral reefs in the Anthropocene are being subjected to unprecedented levels of stressors, including local disturbances—such as overfishing, habitat destruction, and pollution—and large-scale destruction related to the global impacts of climate change—such as typhoons and coral bleaching. Thus, the future of corals and coral reefs in any given community and coral-Symbiodiniaceae associations over time will depend on their level of resilience, from individual corals to entire ecosystems. Herein we review the environmental settings and long-term ecological research on coral reefs, based on both coral resilience and space, in Kenting National Park (KNP), Hengchun Peninsula, southern Taiwan, wherein fringing reefs have developed along the coast of both capes and a semi-closed bay, known as Nanwan, within the peninsula. These reefs are influenced by a branch of Kuroshio Current, the monsoon-induced South China Sea Surface Current, and a tide-induced upwelling that not only shapes coral communities, but also reduces the seawater temperature and creates fluctuating thermal environments which over time have favoured thermal-resistant corals, particularly those corals close to the thermal effluent of a nuclear power plant in the west Nanwan. Although living coral cover (LCC) has fluctuated through time in concordance with major typhoons and coral bleaching between 1986 and 2019, spatial heterogeneity in LCC recovery has been detected, suggesting that coral reef resilience is variable among subregions in KNP. In addition, corals exposed to progressively warmer and fluctuating thermal environments show not only a dominance of associated, thermally-tolerant Durusdinium spp. but also the ability to shuffle their symbiont communities in response to seasonal variations in seawater temperature without bleaching. We demonstrate that coral reefs in a small geographical range with unique environmental settings and ecological characteristics, such as the KNP reef, may be resilient to bleaching and deserve novel conservation efforts. Thus, this review calls for conservation efforts that use resilience-based management programs to reduce local stresses and meet the challenge of climate change.


Author(s):  
Levy D. Obonaga ◽  
Mauro Giovanni Zucconi ◽  
Edgardo Londoño-Cruz

Echinoids are an important component of benthic communities; they can directly modify the distribution and relative abundance of algae and corals as well as be an agent in the process of bioerosion. Despite research on echinoids in the Colombian Pacific, the bioerosion rate due to grazing by Diadema mexicanum on the coral reefs of Gorgona Island remains unknown. Therefore,considering the relative high abundance of this echinoid and its potential negative effects on coral reefs, the main objective of this study was to determine the rate of bioerosion. To accomplish this, 1-m2 quadrats were randomly established in each of three reef zones (at lowtide, Backreef: ±1 m depth, Reef plain: ±0.5 m and Reef front: ±3.0 m) of La Azufrada fringing reef (Gorgona Island National Natural Park). Sea urchins were counted and measured (test diameter) inside the quadrats, and 30 urchins per zone (90 in total) were collected toestimate the bioerosion rate. The average sea urchin density and size (±SD) were 8.28±11.65 ind/m2 and 19.62±5.02 mm, respectively. The average bioerosion rate for the reef was 0.083 kg CaCO3/m2/yr, and it was significantly affected by echinoid size (p<0.001) and reefzone (p=0.0002). Additionally, a direct relationship was observed between intestinal calcium carbonate (CaCO3) and depth (p=0.043) and size (p<0.001). Finally, although large sea urchins may have important effects, it is unlikely that the bioerosion caused by D. mexicanumpresents a threat to La Azufrada fringing reef due to its low relative abundance; this is reflected by the relatively low bioerosion rate relative to other reefs in the Tropical Eastern Pacific.


2020 ◽  
Vol 8 (10) ◽  
pp. 760
Author(s):  
Emma V Kennedy ◽  
Julie Vercelloni ◽  
Benjamin P Neal ◽  
Ambariyanto ◽  
Dominic E.P. Bryant ◽  
...  

Karimunjawa National Park is one of Indonesia’s oldest established marine parks. Coral reefs across the park are being impacted by fishing, tourism and declining water quality (local stressors), as well as climate change (global pressures). In this study, we apply a multivariate statistical model to detailed benthic ecological datasets collected across Karimunjawa’s coral reefs, to explore drivers of community change at the park level. Eighteen sites were surveyed in 2014 and 2018, before and after the 2016 global mass coral bleaching event. Analyses revealed that average coral cover declined slightly from 29.2 ± 0.12% (Standard Deviation, SD) to 26.3 ± 0.10% SD, with bleaching driving declines in most corals. Management zone was unrelated to coral decline, but shifts from massive morphologies toward more complex foliose and branching corals were apparent across all zones, reflecting a park-wide reduction in damaging fishing practises. A doubling of sponges and associated declines in massive corals could not be related to bleaching, suggesting another driver, likely declining water quality associated with tourism and mariculture. Further investigation of this potentially emerging threat is needed. Monitoring and management of water quality across Karimunjawa may be critical to improving resilience of reef communities to future coral bleaching.


2015 ◽  
Vol 39 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Arif Seno Adji

Providing accurate information on suitable multispectral satellite sensors for mapping coral reefs in Indonesia is a challenge for coastal remote-sensing experts. As coral reefs vary in spatial extent, shape, length, perimeter and/or distance to shore, the mapping of coral reefs will need different satellite sensors depending on the objectives and the kind of information required. This work compares the suitability of two kinds of multispectral satellite sensors for mapping coral reefs in Indonesia, high and moderate spatial resolution. This was done through a case study of Wakatobi Marine National Park since that represents many types of coral reef in Indonesia (fringing, barrier, atoll, and patch). Indonesian coral reef shapefile data 2010 was downloaded from UNEP (United Nations Environment Programme) website, and Landsat 7 ETM + images, path/row 112/064 was used to determine the terrestrial area of Wakatobi Islands. Both high and moderate spatial resolution sensors are suitable for mapping the benthic communities and geomorphic zones on coral reefs. The former are more accurate but they are also much less cost-effective, especially over large areas.


2021 ◽  
Vol 9 (2) ◽  
pp. 178
Author(s):  
Roberta Trani ◽  
Giuseppe Corriero ◽  
Maria Concetta de Pinto ◽  
Maria Mercurio ◽  
Carlo Pazzani ◽  
...  

Sponges are an important constituent of filter-feeder benthic communities, characterized by high ecological plasticity and abundance. Free bacteria constitute an important quota of their diet, making them excellent candidates in aquaculture microbial bioremediation, where bacteria can be a serious problem. Although there are studies on this topic, certain promising species are still under investigation. Here we report applied microbiological research on the filtering activity of Sarcotragus spinosulus on two different concentrations of the pathogenic bacterium Vibrio parahaemolyticus in a laboratory experiment. To evaluate the effects of the filtration on the surrounding nutrient load, the release of ammonium, nitrate, and phosphate was also measured. The results obtained showed the efficient filtration capability of S. spinosulus as able to reduce the Vibrio load with a maximum retention efficiency of 99.72% and 99.35% at higher and lower Vibrio concentrations, respectively, and remarkable values of clearance rates (average maximum value 45.0 ± 4.1 mL h−1 g DW−1) at the highest Vibrio concentration tested. The nutrient release measured showed low values for each considered nutrient category at less than 1 mg L−1 for ammonium and phosphate and less than 5 mg L−1 for nitrate. The filtering activity and nutrient release by S. spinosulus suggest that this species represents a promising candidate in microbial bioremediation, showing an efficient capability in removing V. parahaemolyticus from seawater with a contribution to the nutrient load.


Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Denise P. Silva ◽  
Helena D. M. Villela ◽  
Henrique F. Santos ◽  
Gustavo A. S. Duarte ◽  
José Roberto Ribeiro ◽  
...  

Abstract Background Beginning in the last century, coral reefs have suffered the consequences of anthropogenic activities, including oil contamination. Chemical remediation methods, such as dispersants, can cause substantial harm to corals and reduce their resilience to stressors. To evaluate the impacts of oil contamination and find potential alternative solutions to chemical dispersants, we conducted a mesocosm experiment with the fire coral Millepora alcicornis, which is sensitive to environmental changes. We exposed M. alcicornis to a realistic oil-spill scenario in which we applied an innovative multi-domain bioremediator consortium (bacteria, filamentous fungi, and yeast) and a chemical dispersant (Corexit® 9500, one of the most widely used dispersants), to assess the effects on host health and host-associated microbial communities. Results The selected multi-domain microbial consortium helped to mitigate the impacts of the oil, substantially degrading the polycyclic aromatic and n-alkane fractions and maintaining the physiological integrity of the corals. Exposure to Corexit 9500 negatively impacted the host physiology and altered the coral-associated microbial community. After exposure, the abundances of certain bacterial genera such as Rugeria and Roseovarius increased, as previously reported in stressed or diseased corals. We also identified several bioindicators of Corexit 9500 in the microbiome. The impact of Corexit 9500 on the coral health and microbial community was far greater than oil alone, killing corals after only 4 days of exposure in the flow-through system. In the treatments with Corexit 9500, the action of the bioremediator consortium could not be observed directly because of the extreme toxicity of the dispersant to M. alcicornis and its associated microbiome. Conclusions Our results emphasize the importance of investigating the host-associated microbiome in order to detect and mitigate the effects of oil contamination on corals and the potential role of microbial mitigation and bioindicators as conservation tools. Chemical dispersants were far more damaging to corals and their associated microbiome than oil, and should not be used close to coral reefs. This study can aid in decision-making to minimize the negative effects of oil and dispersants on coral reefs.


2015 ◽  
Vol 21 (4) ◽  
pp. 220-226 ◽  
Author(s):  
Shih-Ching Yen ◽  
Kuang-Hsun Chen ◽  
Ying Wang ◽  
Cheng-Ping Wang

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