Variable photo-physiological performance of macroalgae and seagrasses from Saya de Malha and Nazareth Banks, Mascarene Plateau

The photosynthetic performance of macroalgae and seagrasses related to their body parts, depth and colours from the poorly-studied Saya de Malha and Nazareth Banks on the Mascarene Plateau was investigated in this study. Two seagrass (Thalassodendron ciliatum and Halophila decipiens) and seven macroalgae species (Caulerpa cupressoides, Acrosorium ciliolatum, Dictyosphaeria cavernosa, Halimeda opuntia, Ulva sp., Udotea orientalis and Udotea palmetta) were collected using the five Van Veen grabs attached to the Video-Assisted Multi-Sampler (VAMS) from 29-79 m depths in May during the FAO EAF-Nansen Research Programme 2018. The photosynthetic performance was measured using a Diving-Pulse-Amplitude-Modulated (D-PAM) fluorometer and the parameters included effective quantum yield at photosystem II (PSII) (ΦPSII), relative maximum electron transport rate (rETRm), photosynthetic efficiency (α), photoinhibition (β), saturating light level (Ek), and maximum non-photochemical quenching (NPQmax). All photo-physiological parameters varied significantly in T. ciliatum and C. cupressoides across their body parts. However, variation with seawater depths was not significant for NPQmax and β in the seagrass, and ΦPSII, rETRm and β in the macroalgae. Photo-physiological functioning of the leaf of T. ciliatum was optimal at 40 m. The photosynthetic performance of the frond and stolon of C. cupressoides decreased and remained unchanged, respectively, at 79 m when compared to that at 29 m. The whitish lobes of H. opuntia at 31 m exhibited significantly lower photosynthetic performance, in terms of ΦPSII, rETRm,α and Ek, than the greenish lobes. These findings provide a first insight of seaplant body parts-, depth- and colour-related photo-physiological performance from the Mascarene Plateau

First field observations of Halimeda beds at depths of 37-62 m at Saya de Malha and Nazareth banks, Mascarene Plateau

Field note - N/

Photo-physiology of healthy and bleached corals from the Mascarene Plateau

This study presents the first report of variable photo-physiology of healthy-looking and bleached corals from the upper mesophotic waters of the Mascarene Plateau. In May 2018, during the FAO EAF-Nansen research expedition cruise, coral bleaching was visually observed. Five coral species from Saya de Malha Bank, namely Heliopora coerulea, Favites sp. and Porites sp. from 27 m and Acropora sp. and Lithophyllon repanda from 30 m, and three coral species from the Nazareth Bank, namely Acropora sp. and Galaxea fascicularis from 36 m and Stylophora-like species from 58 m were studied using the Video-Assisted Multi-Sampler (VAMS) and collected using a Van Veen grab. Chlorophyll a fluorescence parameters such as effective quantum yield at photosystem II (ΦPSII), relative maximum electron transport rate (rETRm), photosynthetic efficiency (α), photoinhibition (β), saturating light level (Ek), and  maximum non-photochemical quenching (NPQm) were measured using a Diving-Pulse-Amplitude-Modulated (D-PAM) fluorometer to study variable photo-physiology in bleached and non-bleached corals. All photo-physiological parameters varied significantly among coral species tested and between coral conditions, except for β. The interaction between species and coral conditions was only significant in the case of β, but generally not significant. A two-way ANOVA indicated significant effects of depth and coral conditions in Acropora sp. on almost all photo-physiological parameters, except for β, and the effect of depth on rETRmax and α, and the effect of depth along with its interaction with coral conditions on Ek. ΦPSII did not differ in bleached and healthy-looking coral parts of Porites and Lithophyllon from 27 m, Galaxea and Acropora from 36 m while it decreased significantly in Heliopora and Favites at 27 m, Acropora from 30 m, and Stylophora-like at 58 m. NPQm did not change for Porites, Acropora (30 m) and Galaxea but it tended to increase for Heliopora, Acropora (36 m), Lithophyllon, Galaxea, and decrease for Favities, Acropora (30 m) and Stylophora-like. The thermally tolerant coral Porites exhibited normal photo-physiology even in bleached conditions while the bleached parts of Favites, Acropora (30 m) and Stylophora-like corals exhibited photo-physiological dysfunctioning. This study revealed that the seven studied corals from the upper mesophotic waters of the Mascarene Plateau are not spared from the bleaching phenomenon and exhibit variable photo-physiology in bleached and non-bleached conditions. Further studies are warranted to thoroughly understand the coral bleaching patterns and severity during summer periods at the Saya de Malha and Nazareth Banks

Challenges and Opportunities in the Present Era of Marine Algal Applications

Marine algae are of high importance in their natural habitats and even more now in the world of green technology. The sprouting interest of the scientific community and industries in these organisms is driven by the fast-growing world of modern biotechnology. Genomics, transcriptomics, proteomics, metabolomics and their integration collectively termed here as ‘marine algal-omics’ have broadened the research horizon in view of enhancing human’s life by addressing environmental problems and encouraging novelty in the field of pharmaceuticals among so many more. Their use in the human society dates back to 500 B. C. in China and later across the globe; they are still being used for similar purposes and more today. There is a hiking interest in marine algae and their derivatives—from phycoremediation, food supplements, pharmaceuticals to dyes. Marine algae are currently considered as an emerging panacea for the society. They are being studied in a multitude of arenas. The multi-use of marine algae is enticing and promises to be a boon for industrial applications. Yet, most marine algae face challenges that might variably constrain their commercialisation. This chapter gives an overview of marine algae including all the ‘omics’ technologies involved in studying marine algae and it explores their multitude applications. It also draws the various successful industries budded around them and presents some of the challenges and opportunities along with future directions

Field observation of five Stylophora pistillata-like morphotypes near Mauritius Island

Field Note under WIOJMS Special Issue icw UoM Research Week 201

Field observation of five Stylophora pistillata-like morphotypes near Mauritius Island

info:eu-repo/semantics/publishe

Chlorophyll fluorescence – A tool to assess photosynthetic performance and stress photophysiology in symbiotic marine invertebrates and seaplants

Chlorophyll a fluorescence is increasingly being used as a rapid, non-invasive, sensitive and convenient indicator of photosynthetic performance in marine autotrophs. This review presents the methodology, applications and limitations of chlorophyll fluorescence in marine studies. The various chlorophyll fluorescence tools such as Pulse-Amplitude-Modulated (PAM) and Fast Repetition Rate (FRR) fluorometry used in marine scientific studies are discussed. Various commonly employed chlorophyll fluorescence parameters are elaborated. The application of chlorophyll fluorescence in measuring natural variations, stress, stress tolerance and acclimation/adaptation to changing environment in primary producers such as microalgae, macroalgae, seagrasses and mangroves, and marine symbiotic invertebrates, namely symbiotic sponges, hard corals and sea anemones, kleptoplastic sea slugs and giant clams is critically assessed. Stressors include environmental, biological, physical and chemical ones. The strengths, limitations and future perspectives of the use of chlorophyll fluorescence technique as an assessment tool in symbiotic marine organisms and seaplants are discussed. [Display omitted