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1

Historical occurrences of marine microalgal blooms in Indian peninsula : Probable causes and implications

Oyeku Oyeshina Gideon, Mandal Subir Kumar

Oceanologia

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2021

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No. 63 (1)

51--70

EN

The Indian marine environment supports employment for over 200 million people, including revenue of nearly $7 billion per annum. However, ecological goods and services of the shallow coast and the marine environment of the Indian peninsula are being affected by recurrent blooms of microalgae. One hundred and six published literature, starting from the first report in 1908 to 2017, were reviewed to investigate the historical occurrences of marine microalgal blooms (MMBs) around the Indian peninsula. 154 MMBs comprising 24 genera and 7 classes were reported during the study period. Noctiluca (dinophyceae) and Trichodesmium (cyanophyceae) bloom contributed 34.4% and 31.8% of total blooms. PCA revealed that high sea surface temperature (SST) and salinity were significant driving forces for Trichodesmium blooms formation, while high nutrients (NO3-N, PO4-P, and SiO4-Si) and low salinity triggered prymnesiophyceae, raphidophyceae, bacillariophyceae and most of the dinophyceae blooms. Noctiluca blooms were linked with both eutrophication and the abundance of prey organisms. HABs were generally dinophyceae dominated and were associated with mass mortality of aquatic fauna, human intoxication, paralytic, and ciguatera shellfish poisoning and even death. Increasing SST and anthropogenic influences around the Indian peninsula could increase the occurrences of MMBs (including HABs) and the number of causative taxa. Proper safety measures such as routine monitoring of phycotoxin levels in the environment and local seafood are required to be put in place in other to protect the health of the public.

2

Occurrence of a multi-species diatom bloom dominated by Proboscia alata (Brightwell) Sandstorm along the southwest coast of India

Cicily L. T., Padmakumar K. B., Asha Devi C. R., Sanjeevan V. N.

Oceanological and Hydrobiological Studies

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2013

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Vol. 42, No. 1

40-45

EN

The present communication reports on the occurrence of a multi-species diatom bloom in the upwelled waters along the southwest coast of India. During the late summer monsoon season (September 2009) a multi-species diatom bloom with a pale green discoloration of the sea surface was observed in the coastal waters of southwest coast of India. The bloom spread over an area of approximately 15 km2 along the coastal waters off Kannur (Lat. 11°59.471 N, Long. 75°03.446 E). Total diatom cell density of the bloom area was 16 × 104 cells l-1. Proboscia (=Rhizosolenia) alata (Brightwell) Sandstrom constituted 90% of the total phytoplankton population. Other phytoplankton groups that contributed to the bloom population included Chaetoceros spp., Pseudo-nitzschia spp., Rhizosolenia spp., Coscinodiscus sp., Leptocylindrus danicus, Thalassiosira sp., and Bacteriosira sp. Among these Pseudo-nitzschia multiseries, a toxic species with the ability to produce potent neurotoxin domoic acid, was observed with a cell density of 4 × 103 cells l-1. Surface chlorophyll a concentration of the bloom region was 14.1 μg l-1. Nutrient concentrations of the bloom area were 0.01 μmol l-1 for NO2-N, 0.1 ěmol l-1 for NO3- N, 0.83 μmol l-1 for PO4-P and 11.44 μmol l-1 for SiO4.

3

Characterization of phycotoxins produced by cyanobacteria

Mazur-Marzec H.

Oceanological and Hydrobiological Studies

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2006

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Vol. 35, No.1

85-109

EN

Cyanobacteria (blue-green algae), photosynthetic prokaryotes, are essential elements of aquatic ecosystems. They produce a great variety of secondary metabolites; some of which have potentially useful pharmaceutical properties as anti-tumour, antibacterial and antiviral agents. Some species of cyanobacteria form blooms and become dominant over other forms of aquatic life. Blooms can deteriorate water quality in a variety of ways. Blooms formed by toxic species are the most harmful, as they can cause poisoning and death of organisms that come into contact with them. In this review, the structure and activity of cyanobacterial toxins are described. The toxins are classified into: hepatotoxins, neurotoxins, dermatotoxins and endotoxic lipopolysaccharides. Hepatotoxic cyclic pentapeptides, microcystins and nodularins, are the most common cyanobacterial toxins that have been identified in strains of Microcystis, Anabaena, Nodularia, Planktothrix (Oscillatoria), Nostoc, Hapalosiphon and Anabaenopsis. Cylindrospermopsin, another cyanobacterial hepatotoxin, is produced mainly by Cylindrospermopsis raciborskii. There are several neurotoxins produced by the cyanobacterial genera Anabaena, Aphanizomenon, Planktothrix and Cylindrospermopsis. Based on their activity, these neurotoxins were classified into anatoxin-a, anatoxin-a(S) and saxitoxins. BMAA is a novel cyanobacterial neurotoxin implicated in the ALS/PDC syndrome in the Chamorro people of Guam. The occurrence and harmful effects of cyanobacterial dermatotoxins and endotoxic lipopolysaccharides are less well recognised.

4

A simple tool for the early prediction of the cyanobacteria Nodularia spumigena bloom biomass in the Gulf of Finland

Lilover M-J., Laanemets J.

Oceanologia

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2006

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No. 48 (S)

213-229

EN

A fuzzy logic model for predicting the maximum biomass of the toxic cyanobacteria Nodularia spumigena bloom in the Gulf of Finland is suggested. The model bloom biomass depends on the phosphate conditions up to 15 June, including the excess phosphate left over after the spring bloom and on the phosphate inputs parameterised by wind mixing and upwelling from 1 May to 15 June. The surface layer temperature, set to vary from 14 to 23^(o)C, is regarded as a bloom regulating parameter. The model simulations showed that the predicted N. spumigena biomasses differ markedly from year to year and clearly depend on phosphate conditions up to 15 June.