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December 5, 2023
Abstract
Fukuyoa species are potential producers of polyether neurotoxins that are toxic to aquatic biota and humans. A strain of Fukuyoa (CSIRCSMCRI 004) was isolated from India’s Bay of Bengal coast. The clonal culture was identified using light and scanning electron microscopy and molecular phylogenetic analysis of the LSU rRNA gene and ITS (ITS1-5.8S gene-ITS2) sequences. Its toxicity was assessed using a 48 h Artemia bioassay. The morphological features observed included globular shape, descending cingular displacement, broad pentagonal 1′ plate, and large second apical plate (2′). The identity of the strain was confirmed to be F. paulensis based on the LSU rRNA gene and ITS sequences phylogenies. Strain CSIRCSMCRI 004 shared an identical sequence with the type strain of F. paulensis and other strains reported from different locations, based on the LSU rRNA gene and ITS sequences phylogenies. Exposure of brine shrimp larvae to its cellular lysate resulted in lethality (48 h LC 50 = 0.256 mg ml −1 ) and behavioral abnormalities . The current study provides the first evidence of F. paulensis in the Bay of Bengal. It also reveals that CSIRCSMCRI 004 is toxic to susceptible biota like the brine shrimp and could produce ciguatera-associated toxins. The findings of this study highlight the need for sampling and screening of ciguatera-related species in the Bay of Bengal region to understand the associated public and environmental health risks.
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November 30, 2023
Abstract
Fleshy macroalgae dominate the hard bottom, shallow waters along the Western Antarctic Peninsula (WAP). Although there are numerous reports on their ecology, geographic distribution, and to a lesser extent, vertical (depth) distribution in the northern portions of the WAP, much less is known farther south along the central portion of the WAP. Here we provide the first report of the vertical distributions of brown and red fleshy macroalgae in this region based on scuba-derived collections at 14 study sites between southern Anvers Island (64.8°S, 64.4°W) in the north and central Marguerite Bay (68.7°S, 67.5°W) in the south. Although several overstory brown macroalgal species that can be common along the northern WAP including Desmarestia anceps and Cystosphaera jacquinotii are mostly absent from the central WAP, the vertical distributions of the brown macroalgae Desmarestia menziesii and Himantothallus grandifolius are similar to the northern WAP even though their percent cover is much lower. Likewise, the vertical distribution of the 14 most widespread red macroalgae, where they occur, mirrored those known from the northern part of the WAP even though macroalgal cover, biomass, and total species richness declined markedly to the south across this region due to increasing sea ice concentrations.
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Open Access
October 27, 2023
Abstract
Axenic cultures of the green seaweed Ulva mutabilis were inoculated with bacteria providing essential algal growth and morphogenesis-promoting factors (AGMPFs) and were exposed to temperature shifts from 18 °C to 30 °C. The temperature-dependent effect of bacteria on longitudinal algal growth and the molecular composition of the chemosphere in the algal culture medium was explored. The reductionist tripartite model system of U. mutabilis , Roseovarius sp. MS2, and Maribacter sp. MS6 was applied as a reference and has been changed by substituting Roseovarius with isolates that phenocopy this strain. Rathayibacter festucae IH2 and Roseovarius aestuarii G8 boosted growth at 18 °C but slowed it down at 30 °C. Additional inoculation of Roseovarius sp. MS2 mitigated these adverse bacterial effects partially. At 30 °C, the molecular profile of the chemosphere differed dramatically between all tested tripartite communities, indicating different traits of the same bacterium with changing temperatures. Functional examinations should, therefore, accompany microbiome analysis to detect changing traits with the same microbiome composition.
