Available Online at http://www.recentscientific.com International Journal of CODEN: IJRSFP (USA) Recent Scientific
International Journal of Recent Scientific Research Research Vol. 10, Issue, 09(A), pp. 34581-34583, September, 2019 ISSN: 0976-3031 DOI: 10.24327/IJRSR Research Article
IMPACT OF TOXIC CYANOBACTERIUM LYNGBYA MAJUSCULA AND GREEN ALGAE ULVA RETICULATA BLOOMS ON CORALS REEFS OF GULF OF MANNAR, INDIA
Ramesh CH1*, Koushik S1, Shunmugaraj T1 and Ramana Murthy M.V2
1National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES) NCCR Field Office, Mandapam-623519, Tamil Nadu, India 2National Centre for Coastal Research, Pallikaranai, Chennai-600100, Tamil Nadu, India
DOI: http://dx.doi.org/10.24327/ijrsr.2019.1009.3926
ARTICLE INFO ABSTRACT
Article History: Coral reefs in the Gulf of Mannar Marine Biosphere Reserve (GOMMBR) have been facing potential threats from bleaching, sedimentation and significantly algal assemblages. In the present Received 13th June, 2019 th study, bloom of cyanobacterium Lyngbye majuscule overgrowing reef building corals Acropora sp., Received in revised form 11 July, 2019 Porites sp., Echinopora sp. and Goniastrea sp. was observed in Poovarasanpatti Island. Sediment Accepted 8th August, 2019 th deposition is predominant on reef areas and supported the settlement and development of L. Published online 28 September, 2019 majuscula bloom. Although, during summer season L. majuscula is distributed in all other islands, bloom was observed in Poovarasanpatti Island merely. While, green algae, Ulva reticulata bloom was recorded in all the islands of Gulf of Mannar. Reticulate structure of U. reticulata thalli Key Words: observed to cause entanglement to different substrates, thus overgrowing on variety of substrates
Lyngbya majuscula, Ulva reticulata, coral such as live corals Porites sp. and Acropora sp., rubbles, dead reefs, rocks, seaweeds and seagrass. reefs, Gulf of Mannar. Bloom of U. reticulata was occurred due to elevated temperatures of 32°C to 36°C observed during the period from February to May 2019. Considerably, both L. majuscula and U. reticulata blooms caused smothering and tissue discoloration in different corals. Further surveysare undertaken to assess the toxic properties of L. majuscula and Ulva reticulata blooms on live coral cover.
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INTRODUCTION Ulva species are known to be an indication to eutrophication in coastal waters by resulting green tidal blooms in some coastal Blooms of marine microalgae and macroalgae have been areas (Wan et al 2017). Considerably, Ulva species play an documented globally from different coastal areas. However, important role in nutrient cycling in the coastal waters (Human toxic properties of algal blooms are mostly related to et al 2015). Blooms of macroalgae in estuarine and coastal microalgae such as cyanobacteria, dinoflagellates and diatoms. waters are known to affect tourism-based economies, Often, outbursts of these algal blooms are attributed to aquaculture operations, fishing activities and sometimes even eutrophication of coastal waters via favourable environmental replacement of other habitats (Valiela et al 1997; Smetacek and conditions and anthropogenic activities (Fong and Paul Zingone2013). Globally, L. majuscula is well studied and its 2011).Blooms of cyanobacterium Lyngbya majuscula from toxic effects on corals also well understood (Albert et al 2005; different environments have been reported to cause damage to Puyana 2018). In India, blooms of U. lactuca and U. prolifera corals (Albert et al 2005; Puyana 2018). Thus understanding have been reported from mangrove and coral reef environments cyanobacterial blooms that are linked with environmental and (Adhavan et al 2015). However, the impact of U. reticulata seawater quality parameters would greatly help coral reef bloom in the coral reef environment has not been reported so biologists to make effective management strategies to avoid far. damage of coral reefs. Despite of this well-known cyanobacterium, several other macroalgae such as Ulva sp., Coral reefs are the hotspots of marine biodiversity which are Halimeda sp., Caulerpa sp., Sargassum sp. and Turbinaria sp. providing livelihood for coastal communities around the world. are known to pose threat to reefs. However, reefs around the globe are facing potential threats from algal assemblages due to sedimentation and bleaching The green algal genus, Ulva comprises 131 taxonomically effects. Considerably, corals in GOMMBR are facing multiple accepted species of commercial importance (Guiry et al 2014).
*Corresponding author: Ramesh CH National Centre for Coastal Research (NCCR), Ministry of Earth Sciences (MoES) NCCR Field Office, Mandapam-623519, Tamil Nadu, India Ramesh CH et al., Impact of Toxic Cyanobacterium Lyngbya Majuscula and Green Algae Ulva Reticulata Blooms on Corals Reefs of Gulf of Mannar, India stress factors, especially frequent bleaching events, However, there is a significant substratum preference was sedimentation, fishing activities, exotic invasive algal invasion observed for L. majuscula. Profuse growth of this and other macro algal assemblage. In this context, the present cyanobacterium was predominant on live and dead corals, study has aimed to understand the negative impact of bloom rubbles and rocks. Entanglement of L. majuscula on algae forming L. majuscula and U. reticulate on different coral Halimeda sp., Sargassum sp. and Turbinaria sp. was very species in GOMMBR. limited. Bloom of U. reticulata has extensive substrata due to reticular structure of thalli which has ability to entangle all MATERIALS AND METHODS kinds of stable substrates such as rocks, rubbles, live and dead
Reef monitoring surveys were conducted on fringing coral corals, variety of seaweeds and seagrass. However, bloom of L. reefs distributed in four regions namely Mandapam, majuscula caused smothering to 40 to 80% of live corals Keelakarai, Vembar and Tuticorin under GOMMBR. During including Acropora, Echinopora, Pocillopora, Porites and February to May 2019, bleaching of corals was observed in other sub-massive corals Goniastrea and Dipsatraea (Fig. 2).
GOMMBR. Thus, surveys were performed in different islands under the above four regions to assess the bleaching impact on live coral cover. In this process, blooms of toxic cyanobacterium Lyngbya majuscula were observed in Poovarasanpatti Island, while bloom of green algae, Ulva reticulata was observed across all the islands. This study assessed the distribution cover range of these two bloom causing species on coral reefs. Line Intercept Transect method (LIT) was performed to assess the percentage of algal coveron reef biota (English et al 1997). Bloom of L. majuscula was observed under Lynx microscope and photographed. Seawater quality parameters were obtained through Manta+ Water Quality Sonde instrument. Smothering caused by these algae were observed by the presence of algal cover on corals, and tissue damage and tissue discoloration were differentiated by the presence of abundant algal growth on damaged tissue areas and discoloured coral tissue areas respectively. Considerably, among these three, tissue damaged areas are found to be more susceptible to the sediment deposition and algal growth.
RESULTS AND DISCUSSION
Underwater observations revealed profuse and tuft growth of cyanobacterium L. majuscula and U. reticulata on variety of substrata (Fig. 1).
Fig 2 The impact of bloom forming L. majuscula (a) and U. reticulata (b) cover on apical surfaces of different corals; Growth of L. majuscula and U. reticulata on different substrates available in the reef area (c).
Tissue discoloration is found to be greater than tissue damage caused by L. majuscula. In case of U. reticulata bloom, no tissue damage but tissue discoloration was observed relatively less. Both L. majuscula and U. reticulata are apparently found to restrict sunlight availability to zooxanthellae and also caused smothering. U. reticulata showed maximum smothering (50%) on Acropora corals. On the other hand, dead coral reefs are dominantly occupied with mixed algal assemblages including Gracilariasp., Sargassumsp. and Turbinariasp. Water quality parameters obtained during this study have indicated that the
elevated sea surface temperature is responsible for bloom
Fig 1 Bloom of cyanobacterium L. majuscula on Acropora sp. (a), Echinopora lamellosa prevalence of both L. majuscula and U. reticulata (Table 1). (b), dead reef (c), Goniastrea retiformis(d); microscopic view of tuft bloom (e) and single filament (f) of L. majuscula. U. reticulata overgrowing bleached Porites sp. (g), live Table 1 Water quality parameters recorded during bloom Acropora sp. (h), bleached Acropora sp. (i), rubbles and rocks (j), mixed consortium of seaweeds (k) and seagrass (l). events of L. majuscula and U. reticulata.
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DO Salinity Temp pH References (mg/L) (ppt) (°C) 6.38 36.01 7.51 31.91 1. Adhavan D, MarimuthuN, TikadarS, Sivakumar K.
The increasing algal assemblages in coral reefs around the Impact of Algal Bloom on Mangrove and Coral Reef world, including the Great Barrier Reef have been found to Ecosystem in the Marine National Park, Gulf of Kachchh, face severe threats (Albert et al 2005; Puyana 2018). Gujarat, India. J. Marine Biol. Aquacult. 2015; 1(2): 1-2. Considerably, blooms of cyanobacterium L. majuscula pose 2. Albert S, O’Neil JM, Udy JW, Ahern KS, Sullivan CMO, potential threats to corals by causing tissue damages which Dennison WC. Blooms of the cyanobacterium Lyngbya altering the live coral cover in the reef environments (Albert et majuscula in coastal Queensland, Australia: disparate al 2005). Although L. majuscula is prevalent throughout the sites, common factors. Mar. Pollut. Bull. 2005; 51: 428- year, bloom forming conditions are found to be favoured by 437. over sedimentation effect, elevated temperatures and decreased 3. English S, Wilkinson C, Baker V. Survey manual for salinities. Whereas, U. reticulata prevalence was scarce during tropical marine resource. Australian Institute of Marine monsoon and post-monsoon, however, during summer, Sciences, Townsville, Australia, 1997. elevated temperatures found to favour the growth of U. 4. Fong P, Paul VJ. Coral Reef Algae. In: Dubinsky Z, reticulata copiously. Underwater investigations also revealed Stambler N. (Eds.).Coral Reefs: An Ecosystem in that these bloom forming algae were not preferred by any Transition. Springer, B.V., 2011: 241-272. herbivores, indicating their deterrent activity against herbivore 5. Guiry MD, Guiry GM, Morrison L, Rindi F, Miranda SV, fish. A recent study indicated the mortality of fish during Ulva Mathieson AC, Parker BC, Langangen A, John DM, sp. blooms in Gulf of Kachchh, indicating that Ulva sp. are Bárbara I. AlgaeBase: An online resource for algae. deleterious to herbivore fish (Adhavan et al 2015). However, in Cryptogam, Algol. 2014; 35: 105-115. the present study fish mortality was not observed, but it is 6. Human LRD, Snow GC, AdamsJB, Bate GC, Yang SC. evident that herbivore fish population was very less in the study The role of submerged macrophytes and macroalgae in areas. The present study infer that corals in GOMMBR are nutrient cycling: A budget approach. Estuar. Coast Shelf posing potential threat from algal blooms despite of Sci. 2015; 154: 169-178. sedimentation and bleaching events. Therefore, protection and 7. Puyana M. The fate of corals: will they overcome conservation of degrading or existing live coral reefs from competition with algae and cyanobacteria in a changing these threats is an important aspect to pass these valuable environment?, Intech open science. 2018; DOI: ecosystems to future generations. Thus harvesting these bloom 10.5772/intechopen.71568. forming algae for biomedical and industrial applications can be 8. Smetacek V, Zingone A. Green and golden seaweed tides an effective scientific practice and mitigation strategy in on the rise. Nature. 2013; 504: 84-88. GOMMBR. 9. Valiela I, McClelland J, HauxwellJ, Behr PJ, Hersh D, Foreman K. Macroalgal blooms in shallow estuaries: Conflict of Interest Controls and ecophysiological and ecosystem
Authors do not have any conflict of interest. consequences. Limnol. Oceanogr. 1997; 42: 1105-1118 10. Wan AHL, Wilkes RJ, Heesch S, Bermejo R, Johnson Acknowledgements MP, Morrison L. Assessment and Characterisation of
Authors are grateful to Ministry of Earth Sciences, Government Ireland's Green Tides (Ulva Species). PLoS ONE.2017; of India, New Delhi for financial support. We thank field 12(1): e0169049. assistants for the assistance.
How to cite this article:
Ramesh CH et al.2019, Impact of Toxic Cyanobacterium Lyngbya Majuscula and Green Algae Ulva Reticulata Blooms on
Corals Reefs of Gulf of Mannar, India. Int J Recent Sci Res. 10(09), pp. 34581-34583.
DOI: http://dx.doi.org/10.24327/ijrsr.2019.1009.3926
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