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Shirodkar G, Uskaikar H, Naqvi SWA, Pratihary A, Hussain A, Shenoy DM, Gauns M, Manikandan B, Manjrekar S, Patil A. Seasonally varying biogeochemical regime around the coral habitats off central west coast of India. MARINE ENVIRONMENTAL RESEARCH 2024; 196:106427. [PMID: 38479295 DOI: 10.1016/j.marenvres.2024.106427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/24/2024] [Accepted: 02/26/2024] [Indexed: 03/23/2024]
Abstract
The Western Indian Continental Shelf (WICS) experiences upwelling during the Southwest Monsoon (SWM), leading to deoxygenation and acidification of subsurface waters. The region has patchy growth of corals, e.g. in the Grande Island and Angria Bank. Measurements made during the late SWM of 2022 reveal that the shelf waters around the Grande Island were subject to varying environmental conditions, viz. lower temperature (21.3-26.1°C), oxygen (0-4.9 mL L-1) and pHT (7.506-7.927). Complete anoxia was associated with sulphide build-up to a maximum of 5.9 μmol L-1 at 17 m depth. An additional episodic condition (high temperature, low oxygen and pH) also occurred associated presumably with a plankton bloom in April 2017. Hence, unlike the offshore coral site Angria Bank, waters around the Grande Island experiences extreme changes in physico-chemical conditions (e.g. Ωarg ∼1.2-1.8 during October 2022) seasonally as reported here. The biogeochemical conditions are however not as intense (Ωarg = 0.6) as observed along the eastern boundary upwelling system of the Pacific Ocean.
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Affiliation(s)
- Gayatri Shirodkar
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India.
| | - Hema Uskaikar
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | - S W A Naqvi
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | - Anil Pratihary
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | - Afreen Hussain
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | - Damodar M Shenoy
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | - Manguesh Gauns
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | - B Manikandan
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
| | | | - Anagha Patil
- CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India
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Manigandan V, Muthukumar C, Shah C, Logesh N, Sivadas SK, Ramu K, Ramana Murthy MV. Phylogenetic affiliation of Pedinomonas noctilucae and green Noctiluca scintillans nutritional dynamics in the Gulf of Mannar, Southeastern Arabian Sea. Protist 2024; 175:126019. [PMID: 38309038 DOI: 10.1016/j.protis.2024.126019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/05/2024]
Abstract
The present investigation focused on studying the phylogenetic position of the green Noctiluca endosymbiont, Pedinomonas noctilucae, collected from the Gulf of Mannar, India. In this study, we re-examined the evolutionary position of this endosymbiotic algae using rbcL sequences. The phylogenetic analysis revealed that P. noctilucae is distantly related to the Pedinomonas species, and formed a monophyletic clade with Marsupiomandaceae. Based on the phylogenetic association of endosymbiont with Maruspiomonadales it was concluded that the endosymbiont belongs to an independent genus within the family Marsupiomonadaceae. At the site of the bloom, Noctiluca scintillans was found to exhibit a dense monospecific proliferation, with an average cell density of 27.l88 × 103 cells L-1. The investigation revealed that the green Noctiluca during its senescent phase primarily relied on autotrophic nutrition, which was confirmed by the presence of a high number of trophonts, vegetatively reproducing cells (1.45 × 103 cells L-1) and the absence of food vacuoles.
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Affiliation(s)
- Vajravelu Manigandan
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India.
| | - Chandrasekaran Muthukumar
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India
| | - Chinmay Shah
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India
| | - Natarajan Logesh
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India
| | - Sanitha K Sivadas
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India
| | - Karri Ramu
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India
| | - M V Ramana Murthy
- National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES), Chennai 600 100, India
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3
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Strader ME, Wright RM, Pezner AK, Nuttall MF, Aichelman HE, Davies SW. Intersection of coral molecular responses to a localized mortality event and ex situ deoxygenation. Ecol Evol 2024; 14:e11275. [PMID: 38654712 PMCID: PMC11036075 DOI: 10.1002/ece3.11275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 03/22/2024] [Accepted: 04/01/2024] [Indexed: 04/26/2024] Open
Abstract
In July 2016, East Bank of Flower Garden Banks (FGB) National Marine Sanctuary experienced a localized mortality event (LME) of multiple invertebrate species that ultimately led to reductions in coral cover. Abiotic data taken directly after the event suggested that acute deoxygenation contributed to the mortality. Despite the large impact of this event on the coral community, there was no direct evidence that this LME was driven by acute deoxygenation, and thus we explored whether gene expression responses of corals to the LME would indicate what abiotic factors may have contributed to the LME. Gene expression of affected and unaffected corals sampled during the mortality event revealed evidence of the physiological consequences of the LME on coral hosts and their algal symbionts from two congeneric species (Orbicella franksi and Orbicella faveolata). Affected colonies of both species differentially regulated genes involved in mitochondrial regulation and oxidative stress. To further test the hypothesis that deoxygenation led to the LME, we measured coral host and algal symbiont gene expression in response to ex situ experimental deoxygenation (control = 6.9 ± 0.08 mg L-1, anoxic = 0.083 ± 0.017 mg L-1) in healthy O. faveolata colonies from the FGB. However, this deoxygenation experiment revealed divergent gene expression patterns compared to the corals sampled during the LME and was more similar to a generalized coral environmental stress response. It is therefore likely that while the LME was connected to low oxygen, it was a series of interconnected stressors that elicited the unique gene expression responses observed here. These in situ and ex situ data highlight how field responses to stressors are unique from those in controlled laboratory conditions, and that the complexities of deoxygenation events in the field likely arise from interactions between multiple environmental factors simultaneously.
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Affiliation(s)
- Marie E. Strader
- Department of BiologyTexas A&M UniversityCollege StationTexasUSA
| | - Rachel M. Wright
- Department of Biological SciencesSouthern Methodist UniversityDallasTexasUSA
| | | | | | | | - Sarah W. Davies
- Department of BiologyBoston UniversityBostonMassachusettsUSA
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Lin Z, Zhan P, Li J, Sasaki J, Qiu Z, Chen C, Zou S, Yang X, Gu H. Physical drivers of Noctiluca scintillans (Dinophyceae) blooms outbreak in the northern Taiwan Strait: A numerical study. HARMFUL ALGAE 2024; 133:102586. [PMID: 38485436 DOI: 10.1016/j.hal.2024.102586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/03/2024] [Accepted: 01/24/2024] [Indexed: 03/19/2024]
Abstract
The red Noctiluca scintillans (RNS) blooms often break out near Pingtan Island, in the northern Taiwan Strait from April to June. It is essential to gain insights into their formation mechanism to predict and provide early warnings for these blooms. Previous studies and observations showed that RNS blooms are the most likely to occur when winds are weak and shifting in direction. To explore this phenomenon further, we employed a high-resolution coastal model to investigate the hydrodynamics influencing RNS blooms around Pingtan Island from April to June 2022. The model results revealed that seawater exhibited weak circulation but strong stratification during RNS blooms. Residence time were examined through numerical experiments by releasing passive neutrally buoyant particles in three bays of Pingtan Island. The results showed a significantly longer residence time during RNS blooms, indicating reduced flushing capabilities within the bays, which could give RNS a stable environment to multiply and aggregate. This hydrodynamic condition provided a favorable basis for RNS blooms breakout near Pingtan Island. The shifts and weakening of the prevailing northeast wind contributed substantially to weakening the flow field around Pingtan Island and played a crucial role in creating the hydrodynamics conducive to RNS blooms. Our study offers fresh insights into the mechanisms underpinning RNS blooms formation near Pingtan Island, providing a vital framework for forecasting RNS blooms in this region.
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Affiliation(s)
- Zhonghao Lin
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, 210044, China; Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China
| | - Peng Zhan
- Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Jianping Li
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 1068 Xueyuan Avenue, Shenzhen, 518055, China
| | - Jun Sasaki
- Department of Socio-Cultural Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8563, Japan
| | - Zhongfeng Qiu
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, 210044, China
| | - Chun Chen
- Island Research Center, Ministry of Natural Resources, Pingtan, 350400, China
| | - Shuangyan Zou
- Agricultural and rural development service center of Pingtan comprehensive experimental area, Fuzhou, 350004, China
| | - Xiaotong Yang
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, 210044, China; Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China
| | - Haifeng Gu
- School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing, 210044, China; Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China; Observation and Research Station of Island and Coastal Ecosystem in the Western Taiwan Straits, MNR, Xiamen, 361005, China.
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Terzin M, Laffy PW, Robbins S, Yeoh YK, Frade PR, Glasl B, Webster NS, Bourne DG. The road forward to incorporate seawater microbes in predictive reef monitoring. ENVIRONMENTAL MICROBIOME 2024; 19:5. [PMID: 38225668 PMCID: PMC10790441 DOI: 10.1186/s40793-023-00543-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/11/2023] [Indexed: 01/17/2024]
Abstract
Marine bacterioplankton underpin the health and function of coral reefs and respond in a rapid and sensitive manner to environmental changes that affect reef ecosystem stability. Numerous meta-omics surveys over recent years have documented persistent associations of opportunistic seawater microbial taxa, and their associated functions, with metrics of environmental stress and poor reef health (e.g. elevated temperature, nutrient loads and macroalgae cover). Through positive feedback mechanisms, disturbance-triggered heterotrophic activity of seawater microbes is hypothesised to drive keystone benthic organisms towards the limit of their resilience and translate into shifts in biogeochemical cycles which influence marine food webs, ultimately affecting entire reef ecosystems. However, despite nearly two decades of work in this space, a major limitation to using seawater microbes in reef monitoring is a lack of a unified and focused approach that would move beyond the indicator discovery phase and towards the development of rapid microbial indicator assays for (near) real-time reef management and decision-making. By reviewing the current state of knowledge, we provide a comprehensive framework (defined as five phases of research and innovation) to catalyse a shift from fundamental to applied research, allowing us to move from descriptive to predictive reef monitoring, and from reactive to proactive reef management.
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Affiliation(s)
- Marko Terzin
- Australian Institute of Marine Science, PMB no3 Townsville MC, Townsville, QLD, 4810, Australia.
- College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
- AIMS@JCU, James Cook University, Townsville, QLD, 4811, Australia.
| | - Patrick W Laffy
- Australian Institute of Marine Science, PMB no3 Townsville MC, Townsville, QLD, 4810, Australia
- AIMS@JCU, James Cook University, Townsville, QLD, 4811, Australia
| | - Steven Robbins
- Australian Centre for Ecogenomics, University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Yun Kit Yeoh
- Australian Institute of Marine Science, PMB no3 Townsville MC, Townsville, QLD, 4810, Australia
- AIMS@JCU, James Cook University, Townsville, QLD, 4811, Australia
| | - Pedro R Frade
- Natural History Museum Vienna, 1010, Vienna, Austria
| | - Bettina Glasl
- Division of Microbial Ecology, Centre for Microbiology and Environmental Systems Science, University of Vienna, 1030, Vienna, Austria
| | - Nicole S Webster
- Australian Institute of Marine Science, PMB no3 Townsville MC, Townsville, QLD, 4810, Australia
- Australian Centre for Ecogenomics, University of Queensland, St. Lucia, QLD, 4072, Australia
- Australian Antarctic Program, Department of Climate Change, Energy, the Environment and Water, Kingston, TAS, 7050, Australia
| | - David G Bourne
- Australian Institute of Marine Science, PMB no3 Townsville MC, Townsville, QLD, 4810, Australia.
- College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
- AIMS@JCU, James Cook University, Townsville, QLD, 4811, Australia.
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6
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Roy R, Lotliker AA, Baliarsingh SK, Jayaram C. Water column properties associated with massive algal bloom of green Noctiluca scintillans in the Arabian Sea. MARINE POLLUTION BULLETIN 2024; 198:115913. [PMID: 38104382 DOI: 10.1016/j.marpolbul.2023.115913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023]
Abstract
An algal bloom of Noctiluca scintillans (NS) was monitored for 20 days in the Arabian Sea during February 2017. The stations under the influence of NS had low temperature and high salinity compared to outside indicating influence of convective mixing. The microscopic cell count of NS reached a value of 52,600 cells l-1. The surface variability in oxygen and pCO2 measured alongside showed a strong disconnect. Modest supersaturation of surface waters (ΔpCO2 = 3-75 μatm) was observed around the NS bloom compared to outside. However, as these stations were under the influence of convective mixing, the observed change in pCO2 due to subsurface ventilation cannot be ruled out. From the viewpoint of climate change and its influence on oceanic processes, constant monitoring of this bloom becomes essential due to its survival strategy in nutrient-depleted conditions and light of the present observations.
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Affiliation(s)
- Rajdeep Roy
- Regional Remote Sensing Centre - East, National Remote Sensing Centre, Indian Space Research Organisation, Kolkata 700156, India.
| | - Aneesh A Lotliker
- Indian National Centre for Ocean Information Services, Ministry of Earth Sciences, Hyderabad 500090, India
| | - Sanjiba Kumar Baliarsingh
- Indian National Centre for Ocean Information Services, Ministry of Earth Sciences, Hyderabad 500090, India
| | - Chiranjivi Jayaram
- Regional Remote Sensing Centre - East, National Remote Sensing Centre, Indian Space Research Organisation, Kolkata 700156, India
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Lincoln S, Chowdhury P, Posen PE, Robin RS, Ramachandran P, Ajith N, Harrod O, Hoehn D, Harrod R, Townhill BL. Interaction of climate change and marine pollution in Southern India: Implications for coastal zone management practices and policies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 902:166061. [PMID: 37543339 DOI: 10.1016/j.scitotenv.2023.166061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/07/2023]
Abstract
Climate change and marine litter are inextricably linked, and their interaction manifests differently depending on the specific environmental and biological characteristics, and other human activities taking place. The negative impacts resulting from those synergistic interactions are threatening coastal and marine ecosystems and the many goods and services they provide. This is particularly pervasive in the coastal zone of the Indian subcontinent. India is already experiencing severe climate change impacts, which are projected to worsen in the future. At the same time, the country is gripped by a litter crisis that is overwhelming authorities and communities and hindering the country's sustainable development goals. The coastal environment and communities of the southern states of Kerala and Tamil Nadu are particularly vulnerable to the impacts of climate change. While these state governments and authorities are stepping up efforts to improve the management of their coastal zones, the scale and severity of these issues are mounting. Here we review the combined effects of climate change and marine litter pollution in Southern India, focusing on the Gulf of Mannar Reserve in Tamil Nadu and the Malabar Coast in Kerala. Finally, we discuss effective management options that could help improve resilience and sustainability.
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Affiliation(s)
- Susana Lincoln
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom.
| | - Piyali Chowdhury
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom
| | - Paulette E Posen
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom
| | - R S Robin
- National Centre for Sustainable Coastal Management, Ministry of Environment, Forest and Climate Change, Chennai 600 025, India
| | - Purvaja Ramachandran
- National Centre for Sustainable Coastal Management, Ministry of Environment, Forest and Climate Change, Chennai 600 025, India
| | - Nithin Ajith
- National Centre for Sustainable Coastal Management, Ministry of Environment, Forest and Climate Change, Chennai 600 025, India
| | - Olivia Harrod
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom
| | - Danja Hoehn
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom
| | - Richard Harrod
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom
| | - Bryony L Townhill
- International Marine Climate Change Centre, The Centre for Environment, Fisheries and Aquaculture Science (Cefas), Cefas Laboratory, Pakefield Road, Lowestoft, Suffolk NR33 0HT, United Kingdom
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Lee Y, Byeon E, Kim DH, Maszczyk P, Wang M, Wu RSS, Jeung HD, Hwang UK, Lee JS. Hypoxia in aquatic invertebrates: Occurrence and phenotypic and molecular responses. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 263:106685. [PMID: 37690363 DOI: 10.1016/j.aquatox.2023.106685] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/27/2023] [Accepted: 09/01/2023] [Indexed: 09/12/2023]
Abstract
Global deoxygenation in aquatic systems is an increasing environmental problem, and substantial oxygen loss has been reported. Aquatic animals have been continuously exposed to hypoxic environments, so-called "dead zones," in which severe die-offs among organisms are driven by low-oxygen events. Multiple studies of hypoxia exposure have focused on in vivo endpoints, metabolism, oxidative stress, and immune responses in aquatic invertebrates such as molluscs, crustaceans, echinoderms, and cnidarians. They have shown that acute and chronic exposure to hypoxia induces significant decreases in locomotion, respiration, feeding, growth, and reproduction rates. Also, several studies have examined the molecular responses of aquatic invertebrates, such as anaerobic metabolism, reactive oxygen species induction, increased antioxidant enzymes, immune response mechanisms, regulation of hypoxia-inducible factor 1-alpha (HIF-1α) genes, and differently expressed hemoglobin/hemocyanin. The genetic basis of those molecular responses involves HIF-1α pathway genes, which are highly expressed in hypoxic conditions. However, the identification of HIF-1α-related genes and understanding of their applications in some aquatic invertebrates remain inadequate. Also, some species of crustaceans, rotifers, sponges, and ctenophores that lack HIF-1α are thought to have alternative defense mechanisms to cope with hypoxia, but those factors are still unclear. This review covers the formation of hypoxia in aquatic environments and the various adverse effects of hypoxia on aquatic invertebrates. The limitations of current hypoxia research and genetic information about the HIF-1α pathway are also discussed. Finally, this paper explains the underlying processes of the hypoxia response and presents an integrated program for research about the molecular mechanisms of hypoxic stresses in aquatic invertebrates.
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Affiliation(s)
- Yoseop Lee
- Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Eunjin Byeon
- Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Duck-Hyun Kim
- Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 16419, South Korea
| | - Piotr Maszczyk
- Department of Hydrobiology, Institute of Functional Biology and Ecology, Faculty of Biology, University of Warsaw, Żwirki i Wigury 101, Warsaw 02-089, Poland
| | - Minghua Wang
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies/College of the Environment & Ecology, Xiamen University, Xiamen 361102, China
| | - Rudolf Shiu Sun Wu
- Department of Science and Environmental Studies, The Education University of Hong Kong, Hong Kong, China; State Key Laboratory of Marine Pollution, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Hee-Do Jeung
- Tidal Flat Research Center, National Institute of Fisheries Science, Gunsan 54001, South Korea
| | - Un-Ki Hwang
- Tidal Flat Research Center, National Institute of Fisheries Science, Gunsan 54001, South Korea
| | - Jae-Seong Lee
- Department of Biological Sciences, College of Science, Sungkyunkwan University, Suwon 16419, South Korea.
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Sathish T, Kuttippurath J, Purushothaman A, Amal KS, Mohan R, John L, Thomas LC, Padmakumar KB. Observed evidence for the impact of coastal currents on the recurrent Noctiluca scintillans blooms in the northwest Indian Ocean coast. MARINE POLLUTION BULLETIN 2023; 194:115426. [PMID: 37611339 DOI: 10.1016/j.marpolbul.2023.115426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/10/2023] [Accepted: 08/14/2023] [Indexed: 08/25/2023]
Abstract
Recently, South Eastern Arabian Sea (SEAS) experiences recurrent winter blooms of green Noctiluca scintillans with serious ecological consequences. Here, the analysis of green N. scintillans blooms in SEAS for the past three consecutive years (2018-2021) is presented. The daily monitoring showed intense winter blooms during November with stable sea surface temperatures, high nitrate-phosphate concentrations and relatively lower pH levels. Dissolved oxygen concentration decreased to near hypoxia in the later stages of the bloom. Our analysis finds that the increased occurrence of N. scintillans blooms along SEAS is driven by the coastal currents (EICC), which transport the bloom species from the east coast (south west Bay of Bengal) to west coast of India. Therefore, the N. scintillans seeding from the South west Bay of Bengal intensifies winter blooms in SEAS, thus unveils the influence of oceanic currents in deciding the phytoplankton blooms across the coastal regions of north Indian Ocean.
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Affiliation(s)
- Twinkle Sathish
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India
| | - Jayanarayanan Kuttippurath
- The Centre for Ocean, River, Atmosphere and Land Sciences (CORAL), Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Aishwarya Purushothaman
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India
| | - K S Amal
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India
| | - Renju Mohan
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India
| | - Lix John
- Department of Physical Oceanography, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India
| | - Lathika Cicily Thomas
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India
| | - K B Padmakumar
- Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Kochi 16, Kerala, India.
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Dilipkumar J, Shanmugam P. Fuzzy-based global water quality assessment and water quality cells identification using satellite data. MARINE POLLUTION BULLETIN 2023; 193:115148. [PMID: 37327718 DOI: 10.1016/j.marpolbul.2023.115148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/31/2023] [Accepted: 06/03/2023] [Indexed: 06/18/2023]
Abstract
The water environmental impact assessment and management programs increasingly rely on accurate and quantitative estimates of water quality parameters through remote sensing, owing to the limitation of the time-consuming field-based approaches. Numerous studies have utilised the remote-derived water-quality products and existing water quality index WQI models, but they are typically site-specific and yield significant errors for the accurate assessment and monitoring of coastal and inland water bodies. This study presents a generalized WQI model that incorporates a flexible number of parameters, simplifying them to produce comprehensive water quality index values with the fuzzy logic approach. To derive these index values, three major water quality parameters such as Chl, TSS and aCDOM443 were estimated using new remote-sensing models, and the corresponding indices Trophic State Index (TSI), Total Suspended Solids Index (TSSI) and CDOM Index (CI) were produced by a generalized index model. Finally, WQI products were derived based on the Mamdani-based Fuzzy Inference System (FIS) and individual contribution of the water quality parameters to WQI was analysed to establish 'Water Quality Cells' WQcells, which are represented by the dominant WQ parameter. The new models were tested on MODIS-Aqua and Sentinel-3 OLCI data in different regional and global oceanic waters. Further, a time series analysis was performed in regional coastal oceanic waters (along the Indian coast) to study the seasonal variations of individual water quality parameters and WQI over the period from 2011 to 2020. The results demonstrated that the FIS is efficient in handling the parameters with varying units and their relative importance. The water quality cells were identified in the bloom-dominated (Arabian Sea), TSS-dominated (Point Calimere, India and Yangtze River estuary, China) and CDOM-dominated (South Carolina coast, USA) regions. The time series analysis revealed that the water quality of the Indian coast exhibits cyclic seasonal variations due to the annual occurrence of the south-west and north-east monsoons. These results are critical for monitoring and assessing the quality of surface waters in coastal and inland environments and enabling water resources managers to formulate and implement management plans for a variety of water bodies cost-effectively.
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Affiliation(s)
- Jayaraj Dilipkumar
- Ocean Optics and Imaging Laboratory, Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - Palanisamy Shanmugam
- Ocean Optics and Imaging Laboratory, Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
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11
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Zahir M, Balaji-Prasath B, Su YP, Feng S, Zou J, Yang Y. The dynamics of red Noctiluca scintillans in the coastal aquaculture areas of Southeast China. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:4995-5012. [PMID: 37027084 DOI: 10.1007/s10653-023-01528-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
Noctiluca scintillans (NS) adds an aesthetic appeal to many coastal areas because of their bioluminescence. An intense bloom of the red NS frequently occurs in the coastal aquaculture region of Pingtan Island in Southeastern China. However, when NS exceeds in abundance, it causes hypoxia which has devastating impacts on the aquaculture. This study was conducted in the Southeastern part of China with an aim to examine the relationship between the profusion of NS and its impacts on marine environment. Samples from four stations on Pingtan Island were collected for 12 months (January to December 2018) and were later analyzed in laboratory against five parameters, namely temperature, salinity, wind speed, dissolved oxygen, and chlorophyll a. Results showed that the NS blooms were particularly active during the months of May and June in the Pingtan Island area. The seawater temperatures during that time were recorded between 20 and 28.8 °C indicating the optimum survival temperature for NS. The NS bloom activity ceased above 28.8 °C. A principal component analysis (PCA) indicated that the richness of NS was positively associated with temperature and salinity, whereas there was a significant reverse correlation between NS accumulation and wind speed. NS is a heterotrophic dinoflagellate and relies on the predation of algae for reproduction; therefore, a significant correlation was observed between NS abundance and chlorophyll a concentration, and an inverse correlation was observed between NS and phytoplankton abundance. Additionally, red NS growth was observed immediately following the diatom bloom, suggesting that phytoplankton, temperature, and salinity are the essential factors in the evolution, progression, and termination of NS growth.
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Affiliation(s)
- Muhammad Zahir
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, People's Republic of China
- Centre for Climate Research and Development (CCRD), COMSATS University Islamabad, Park Road, Tarlai Kalan, Islamabad, 45550, Pakistan
| | - Barathan Balaji-Prasath
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, People's Republic of China
- Fujian Key Laboratory of Pollution Control and Resource Recycling, Fuzhou, 350007, People's Republic of China
- Fujian Province Research Centre for River and Lake Health Assessment, Fuzhou, 350007, People's Republic of China
| | - Yu Ping Su
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, People's Republic of China.
- Fujian Key Laboratory of Pollution Control and Resource Recycling, Fuzhou, 350007, People's Republic of China.
- Fujian Province Research Centre for River and Lake Health Assessment, Fuzhou, 350007, People's Republic of China.
| | - Shenlin Feng
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, People's Republic of China
| | - Jiashu Zou
- College of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, People's Republic of China
| | - Yuxiang Yang
- Environmental monitoring station of the Pingtan Comprehensive Experimental Area, Pingtan, 350499, People's Republic of China
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12
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Zhang K, Wu Z, Liu Z, Tang J, Cai W, An M, Zhou Z. Acute hypoxia induces reduction of algal symbiont density and suppression of energy metabolism in the scleractinian coral Pocillopora damicornis. MARINE POLLUTION BULLETIN 2023; 191:114897. [PMID: 37043929 DOI: 10.1016/j.marpolbul.2023.114897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 02/21/2023] [Accepted: 03/27/2023] [Indexed: 05/13/2023]
Abstract
Loss of oxygen in the ocean is accelerating and threatening the coral reef ecosystem. In this study, the impacts of hypoxia on the scleractinian coral Pocillopora damicornis were explored. The algal symbiont density, chlorophyll a + c2 content, energy consumption of corals, as well as energy available and consumption of their symbionts, decreased significantly post hypoxia stress. Meanwhile, the malondialdehyde contents in corals and symbionts, together with the caspase-3 activation level in corals, increased significantly in response to hypoxia stress. Furthermore, it was revealed that activities such as coral cell division and calcification were inhibited under hypoxia. These results collectively suggest that acute hypoxia stress reduces symbiont density and chlorophyll a + c2 content in the coral P. damicornis by elevating intracellular oxidative pressure and apoptotic level, which further suppresses energy metabolism in the symbiotic association and negatively affects a series of activities such as coral cell division and calcification.
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Affiliation(s)
- Kaidian Zhang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan University, Haikou 570228, China
| | - Zhongjie Wu
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 571126, China
| | - Zhaoqun Liu
- State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan University, Haikou 570228, China.
| | - Jia Tang
- State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan University, Haikou 570228, China
| | - Wenqi Cai
- State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan University, Haikou 570228, China; Hainan Academy of Ocean and Fisheries Sciences, Haikou 571126, China
| | - Mingxun An
- State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan University, Haikou 570228, China
| | - Zhi Zhou
- State Key Laboratory of Marine Resource Utilization in South China Sea, Key Laboratory of Tropical Hydrobiology and Biotechnology of Hainan Province, Hainan University, Haikou 570228, China.
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13
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Thirumalaiselvan PS, Raman M, Remya L, Jayakumar R, Sakthivel M, Tamilmani G, Sankar M, Anikuttan KK, Menon NN, Saravanan R, Ravikumar TT, Narasimapallavan I, Krishnaveni N, Muniasamy V, Batcha SM, Gopalakrishnan A. Monitoring of Harmful Algal Bloom (HAB) of Noctiluca scintillans (Macartney) along the Gulf of Mannar, India using in-situ and satellite observations and its impact on wild and maricultured finfishes. MARINE POLLUTION BULLETIN 2023; 188:114611. [PMID: 36731375 DOI: 10.1016/j.marpolbul.2023.114611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/07/2023] [Accepted: 01/09/2023] [Indexed: 06/18/2023]
Abstract
In the Gulf of Mannar, Noctiluca scintillans blooms have been observed three times in September 2019, September and October 2020, and October 2021. It was determined and measured how the bloom period affects ichthyo-diversity. Noctiluca cell density varied slightly from year to year, ranging from1.8433 × 103 cells/L to 1.3824 x 106cells/L. In surface and sea bottom waters, high ammonia levels and low dissolved oxygen levels were noted. During the bloom period a significant increase in chlorophyll concentration was found. The amount of chlorophyll in GOM was extremely high, according to remote sensing photos made using MODIS-Aqua 4 km data. Acute hypoxia caused the death of wild fish near coral reefs and also in fish reared in sea cages. The decay of the bloom resulted in significant ammonia production, a dramatic drop in the amount of dissolved oxygen in the water, and ultimately stress, shock, and mass mortality of fishes.
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Affiliation(s)
- P S Thirumalaiselvan
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - Mini Raman
- Space Applications Centre, Indian Space Research Organization (ISRO), Ahmedabad, Gujarat 380015, India
| | - L Remya
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - R Jayakumar
- Central Institute of Brackish water Aquaculture, No. 75, Santhome High Road, Chennai, India
| | - M Sakthivel
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - G Tamilmani
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - M Sankar
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - K K Anikuttan
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - N Nandini Menon
- Nansen Environmental Research Centre India (NERCI), Kochi, India
| | - Raju Saravanan
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - T T Ravikumar
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | | | - N Krishnaveni
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - V Muniasamy
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - S M Batcha
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
| | - A Gopalakrishnan
- Mandapam Regional Centre, Central Marine Fisheries Research Institute, Mandapam Camp, India
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14
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Castrillón-Cifuentes AL, Zapata FA, Giraldo A, Wild C. Spatiotemporal variability of oxygen concentration in coral reefs of Gorgona Island (Eastern Tropical Pacific) and its effect on the coral Pocillopora capitata. PeerJ 2023; 11:e14586. [PMID: 36721774 PMCID: PMC9884479 DOI: 10.7717/peerj.14586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/28/2022] [Indexed: 01/27/2023] Open
Abstract
Dissolved oxygen concentration (DO) is one of the main factors limiting benthic species distribution. Due to ocean warming and eutrophication, the ocean is deoxygenating. In the Eastern Tropical Pacific (ETP), deep waters with low DO (<1 mg L-1) may reach coral reefs, because upwelling will likely intensify due to climate change. To understand oxygen variability and its effects on corals, we characterize the Spatio-temporal changes of DO in coral reefs of Gorgona Island and calculate the critical oxygen tension (P crit) to identify the DO concentration that could represent a hypoxic condition for Pocillopora capitata, one of the main reef-building species in the ETP. The mean (±SD) DO concentration in the coral reefs of Gorgona Island was 4.6 ± 0.89 mg L-1. Low DO conditions were due to upwelling, but hypoxia (<3.71 mg L-1, defined as a DO value 1 SD lower than the Mean) down to 3.0 mg O2 L-1 sporadically occurred at 10 m depth. The P crit of P. capitata was 3.7 mg L-1 and lies close to the hypoxic condition recorded on coral reefs during the upwelling season at 10 m depth. At Gorgona Island oxygen conditions lower than 2.3 mg L-1 occur at >20 m depth and coincide with the deepest bathymetric distribution of scattered colonies of Pocillopora. Because DO concentrations in coral reefs of Gorgona Island were comparably low to other coral reefs in the Eastern Tropical Pacific, and the hypoxic threshold of P. capitata was close to the minimum DO record on reefs, hypoxic events could represent a threat if conditions that promote eutrophication (and consequently hypoxia) increase.
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Affiliation(s)
- Ana Lucia Castrillón-Cifuentes
- Department of Marine Ecology/Faculty of Biology and Chemistry, Universität Bremen, Bremen, Germany,Departamento de Biología/Facultad de Ciencias Naturales y Exactas/Grupo de Investigación en Ecología de Arrecifes Coralinos, Universidad del Valle, Cali, Valle del Cauca, Colombia
| | - Fernando A. Zapata
- Departamento de Biología/Facultad de Ciencias Naturales y Exactas/Grupo de Investigación en Ecología de Arrecifes Coralinos, Universidad del Valle, Cali, Valle del Cauca, Colombia
| | - Alan Giraldo
- Departamento de Biología/Facultad de Ciencias Naturales y Exactas/Grupo de Investigación en Ciencias Oceanográficas, Universidad del Valle, Cali, Valle del Cauca, Colombia
| | - Christian Wild
- Department of Marine Ecology/Faculty of Biology and Chemistry, Universität Bremen, Bremen, Germany
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15
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Paramasivam K, Venkataraman K. Comparison of macro‐molluscan assemblages in a protected and a non‐protected tropical seagrass ecosystem. Biotropica 2022. [DOI: 10.1111/btp.13153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- K. Paramasivam
- Marine Biology Regional Centre Zoological Survey of India, Ministry of Environment, Forest and Climate Change (MoEFCC), Government of India Chennai India
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16
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Effects of Hypoxia on Coral Photobiology and Oxidative Stress. BIOLOGY 2022; 11:biology11071068. [PMID: 36101446 PMCID: PMC9312924 DOI: 10.3390/biology11071068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 06/21/2022] [Accepted: 07/08/2022] [Indexed: 11/16/2022]
Abstract
Global ocean oxygen (O2) content is decreasing as climate change drives declines in oxygen solubility, strengthened stratification of seawater masses, increased biological oxygen consumption and coastal eutrophication. Studies on the biological effects of nocturnal decreased oxygen concentrations (hypoxia) on coral reefs are very scarce. Coral reefs are fundamental for supporting one quarter of all marine species and essential for around 275 million people worldwide. This study investigates acute physiological and photobiological responses of a scleractinian coral (Acropora spp.) to overnight hypoxic conditions (<2 mg/L of O2). Bleaching was not detected, and visual and physical aspects of corals remained unchanged under hypoxic conditions. Most photobiological-related parameters also did not show significant changes between treatments. In addition to this, no significant differences between treatments were observed in the pigment composition. However, hypoxic conditions induced a significant decrease in coral de-epoxidation state of the xanthophyll cycle pigments and increase in DNA damage. Although the present findings suggest that Acropora spp. is resilient to some extent to short-term daily oxygen oscillations, long-term exposure to hypoxia, as predicted to occur with climate change, may still have deleterious effects on corals.
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17
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Hughes DJ, Alexander J, Cobbs G, Kühl M, Cooney C, Pernice M, Varkey D, Voolstra CR, Suggett DJ. Widespread oxyregulation in tropical corals under hypoxia. MARINE POLLUTION BULLETIN 2022; 179:113722. [PMID: 35537305 DOI: 10.1016/j.marpolbul.2022.113722] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 04/12/2022] [Accepted: 04/30/2022] [Indexed: 06/14/2023]
Abstract
Hypoxia (low oxygen stress) is increasingly reported on coral reefs, caused by ocean deoxygenation linked to coastal nutrient pollution and ocean warming. While the ability to regulate respiration is a key driver of hypoxia tolerance in many other aquatic taxa, corals' oxyregulatory capabilities remain virtually unexplored. Here, we examine O2-consumption patterns across 17 coral species under declining O2 partial pressure (pO2). All corals showed ability to oxyregulate, but total positive regulation (Tpos) varied between species, ranging from 0.41 (Pocillopora damicornis) to 2.42 (P. acuta). On average, corals performed maximum regulation effort (Pcmax) at low pO2 (30% air saturation, corresponding to lower O2 levels measured on natural reef systems), and exhibited detectable regulation down to as low as <10% air saturation. Our study shows that corals are not oxyconformers as previously thought, suggesting oxyregulation is likely important for survival in dynamic O2 environments of shallow coral reefs subjected to hypoxic events.
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Affiliation(s)
- David J Hughes
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW 2007, Australia.
| | - James Alexander
- Department of Biology, University of Louisville, Louisville, KY 40292, USA
| | - Gary Cobbs
- Department of Biology, University of Louisville, Louisville, KY 40292, USA
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, DK 3000 Helsingør, Denmark
| | - Chris Cooney
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW 2007, Australia
| | - Mathieu Pernice
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW 2007, Australia
| | - Deepa Varkey
- Department of Molecular Sciences, Macquarie University, NSW 2109, Australia
| | | | - David J Suggett
- University of Technology Sydney, Climate Change Cluster, Ultimo, NSW 2007, Australia
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18
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Johnson MD, Swaminathan SD, Nixon EN, Paul VJ, Altieri AH. Differential susceptibility of reef-building corals to deoxygenation reveals remarkable hypoxia tolerance. Sci Rep 2021; 11:23168. [PMID: 34848743 PMCID: PMC8632909 DOI: 10.1038/s41598-021-01078-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/13/2021] [Indexed: 01/16/2023] Open
Abstract
Ocean deoxygenation threatens the persistence of coastal ecosystems worldwide. Despite an increasing awareness that coastal deoxygenation impacts tropical habitats, there remains a paucity of empirical data on the effects of oxygen limitation on reef-building corals. To address this knowledge gap, we conducted laboratory experiments with ecologically important Caribbean corals Acropora cervicornis and Orbicella faveolata. We tested the effects of continuous exposure to conditions ranging from extreme deoxygenation to normoxia (~ 1.0 to 6.25 mg L-1 dissolved oxygen) on coral bleaching, photophysiology, and survival. Coral species demonstrated markedly different temporal resistance to deoxygenation, and within a species there were minimal genotype-specific treatment effects. Acropora cervicornis suffered tissue loss and mortality within a day of exposure to severe deoxygenation (~ 1.0 mg L-1), whereas O. faveolata remained unaffected after 11 days of continuous exposure to 1.0 mg L-1. Intermediate deoxygenation treatments (~ 2.25 mg L-1, ~ 4.25 mg L-1) elicited minimal responses in both species, indicating a low oxygen threshold for coral mortality and coral resilience to oxygen concentrations that are lethal for other marine organisms. These findings demonstrate the potential for variability in species-specific hypoxia thresholds, which has important implications for our ability to predict how coral reefs may be affected as ocean deoxygenation intensifies. With deoxygenation emerging as a critical threat to tropical habitats, there is an urgent need to incorporate deoxygenation into coral reef research, management, and action plans to facilitate better stewardship of coral reefs in an era of rapid environmental change.
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Affiliation(s)
- Maggie D. Johnson
- grid.452909.30000 0001 0479 0204Smithsonian Marine Station, Fort Pierce, FL USA ,grid.1214.60000 0000 8716 3312Tenenbaum Marine Observatories Network, Smithsonian Institution, Edgewater, MD USA ,grid.56466.370000 0004 0504 7510Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA USA ,grid.45672.320000 0001 1926 5090Present Address: Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Sara D. Swaminathan
- grid.15276.370000 0004 1936 8091Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL USA
| | - Emily N. Nixon
- grid.452909.30000 0001 0479 0204Smithsonian Marine Station, Fort Pierce, FL USA
| | - Valerie J. Paul
- grid.452909.30000 0001 0479 0204Smithsonian Marine Station, Fort Pierce, FL USA
| | - Andrew H. Altieri
- grid.15276.370000 0004 1936 8091Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL USA
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19
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Patterson Edward JK, Jayanthi M, Malleshappa H, Immaculate Jeyasanta K, Laju RL, Patterson J, Diraviya Raj K, Mathews G, Marimuthu AS, Grimsditch G. COVID-19 lockdown improved the health of coastal environment and enhanced the population of reef-fish. MARINE POLLUTION BULLETIN 2021; 165:112124. [PMID: 33652256 PMCID: PMC7862902 DOI: 10.1016/j.marpolbul.2021.112124] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 05/06/2023]
Abstract
Reduction in the impact of human-induced factors is capable of enhancing the environmental health. In view of COVID-19 pandemic, lockdowns were imposed in India. Travel, fishing, tourism and religious activities were halted, while domestic and industrial activities were restricted. Comparison of the pre- and post-lockdown data shows that water parameters such as turbidity, nutrient concentration and microbial levels have come down from pre- to post-lockdown period, and parameters such as dissolved oxygen levels, phytoplankton and fish densities have improved. The concentration of macroplastics has also dropped from the range of 138 ± 4.12 and 616 ± 12.48 items/100 m2 to 63 ± 3.92 and 347 ± 8.06 items/100 m2. Fish density in the reef areas has increased from 406 no. 250 m-2 to 510 no. 250 m-2. The study allows an insight into the benefits of effective enforcement of various eco-protection regulations and proper management of the marine ecosystems to revive their health for biodiversity conservation and sustainable utilization.
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Affiliation(s)
| | - M Jayanthi
- Department of Environment, Government of Tamil Nadu, Saidapet, Chennai, India
| | - H Malleshappa
- State Environmental Impact Assessment Authority-TN, Saidapet, Chennai, India
| | | | - R L Laju
- Suganthi Devadason Marine Research Institute, Tuticorin, India
| | | | - K Diraviya Raj
- Suganthi Devadason Marine Research Institute, Tuticorin, India
| | - G Mathews
- Suganthi Devadason Marine Research Institute, Tuticorin, India
| | - A S Marimuthu
- Gulf of Mannar Marine National Park, Ramanathapuram, India
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