Heterogeneity of Fish Taxonomic and Functional Diversity Evaluated by eDNA and Gillnet along a Mangrove-Seagrass-Coral Reef Continuum.

The effective and reliable monitoring of fish communities is important for the management and protection of marine ecosystems. Environmental DNA (eDNA) metabarcoding is a relatively new method that has been widely used in recent years, while traditional sampling via fish catching (i.e., gillnets) is one of the most common and reliable fish monitoring methods used to date. We compared the taxonomic and functional diversity of fish detected within a mangrove-seagrass-coral reef continuum using both survey methods. One liter seawater and gillnet samples were collected in August 2021 from mangrove forests, seagrass meadows and coral reef habitats (n = 3 each) in Hainan, China. Surveys using eDNA and gillnets identified 139 genera belonging to 66 families and 58 genera belonging to 42 families, respectively. Regardless of the survey method, fish detected in mangrove, seagrass and coral reef habitats were heterogeneous in their communities; however, the shared species between habitats suggest some degree of connectivity. There were no significant differences between habitats in terms of taxonomic and functional diversity, but a higher taxonomic diversity was detected using eDNA. Both methods were able to distinguish fish assemblages between different habitats; however, gillnet surveys performed better than eDNA surveys for distinguishing mangrove from seagrass assemblages. Therefore, the concurrent use of eDNA and gillnet survey methods provides a more comprehensive approach to understanding the heterogeneity of fish taxonomic and functional diversity along mangrove-seagrass-coral reef continuums.

Breaking the Barrier: A Study on Multi-drug Resistance in Breast Abscess at an Academic Malaysian Hospital.

BACKGROUND: In recent years, the increase in antibiotics usage locally has led to a worrying emergence of multi-drug resistant organisms (MDRO), with the Malaysian prevalence rate of methicillin-resistant Staphylococcus aureus (MRSA) ranging from 17.2 to 28.1% between 1999 and 2017. A study has shown that 7% of all non-lactational breast abscesses are caused by MRSA. Although aspiration offers less morbidities compared to surgical drainage, about 20% of women infected by MRSA who initially underwent aspiration subsequently require surgical drainage. This study is conducted to determine the link between aetiology, antimicrobial resistance pattern and treatment modalities of breast abscesses. METHODS: Retrospective study of reviewing microbiology specimens of breast abscess patients treated at Universiti Malaya Medical Centre from 2015 to 2020. Data collected from microbiology database and electronic medical records were analysed using SPSS V21. RESULT: A total of 210 specimens from 153 patients were analysed. One-fifth (19.5%) of the specimens isolated were MDRO. Lactational associated infections had the largest proportion of MDR in comparison to non-lactational and secondary infections (38.5%, 21.7%, 25.7%, respectively; p = 0.23). Staphylococcus epidermidis recorded the highest number of MDR (n = 12) followed by S. aureus (n = 8). Adjusted by aetiological groups, the presence of MDRO is linked to failure of single aspirations (p = 0.554) and significantly doubled the risk of undergoing surgical drainage for resolution (p = 0.041). CONCLUSION: MDR in breast abscess should be recognised as an increasing healthcare burden due to a paradigm shift of MDRO and a rise of resistance cases among lactational associated infection that were vulnerable to undergo surgical incision and drainage for resolution.

Transcriptomic analysis reveals distinct mechanisms of adaptation of a polar picophytoplankter under ocean acidification conditions.

Human emissions of carbon dioxide are causing irreversible changes in our oceans and impacting marine phytoplankton, including a group of small green algae known as picochlorophytes. Picochlorophytes grown in natural phytoplankton communities under future predicted levels of carbon dioxide have been demonstrated to thrive, along with redistribution of the cellular metabolome that enhances growth rate and photosynthesis. Here, using next-generation sequencing technology, we measured levels of transcripts in a picochlorophyte Chlorella, isolated from the sub-Antarctic and acclimated under high and current ambient CO2 levels, to better understand the molecular mechanisms involved with its ability to acclimate to elevated CO2. Compared to other phytoplankton taxa that induce broad transcriptomic responses involving multiple parts of their cellular metabolism, the changes observed in Chlorella focused on activating gene regulation involved in different sets of pathways such as light harvesting complex binding proteins, amino acid synthesis and RNA modification, while carbon metabolism was largely unaffected. Triggering a specific set of genes could be a unique strategy of small green phytoplankton under high CO2 in polar oceans.

Marine Autotroph-Herbivore Synergies: Unravelling the Roles of Macroalgae in Marine Ecosystem Dynamics.

Species invasion is a leading threat to marine ecosystems worldwide, being deemed as one of the ultimate jeopardies for biodiversity along with climate change. Tackling the emerging biodiversity threat to maintain the ecological balance of the largest biome in the world has now become a pivotal part of the Sustainable Development Goals (SDGs). Marine herbivores are often considered as biological agents that control the spread of invasive species, and their effectiveness depends largely on factors that influence their feeding preferences, including the specific attributes of their food-the autotrophs. While the marine autotroph-herbivore interactions have been substantially discussed globally, many studies have reported contradictory findings on the effects of nutritional attributes and novelty of autotrophs on herbivore feeding behaviour. In view of the scattered literature on the mechanistic basis of autotroph-herbivore interactions, we generate a comprehensive review to furnish insights into critical knowledge gaps about the synergies based largely on the characteristics of macroalgae; an important group of photosynthetic organisms in the marine biome that interact strongly with generalist herbivores. We also discuss the key defence strategies of these macroalgae against the herbivores, highlighting their unique attributes and plausible roles in keeping the marine ecosystems intact. Overall, the feeding behaviour of herbivores can be affected by the nutritional attributes, morphology, and novelty of the autotrophs. We recommend that future research should carefully consider different factors that can potentially affect the dynamics of the marine autotroph-herbivore interactions to resolve the inconsistent results of specific attributes and novelty of the organisms involved.

Impact of elevated temperature on the physiological and biochemical responses of Kappaphycus alvarezii (Rhodophyta).

The eucheumatoids Kappaphycus and Eucheuma are cultivated in tropical or subtropical regions for the production of carrageenan, a hydrocolloid widely used in the food and cosmetic industries. Kappaphycus alvarezii is a highly valued economic crop in the Coral Triangle, with the Philippines, Indonesia and Malaysia ranked among the largest producers. In the absence of measures to mitigate climate change, extreme events including heatwaves, typhoons, severe El Niño and La Niña, are expected to increase in frequency and magnitude. This inadvertently brings adverse effects to the seaweed cultivation industry, especially in the tropics. Temperatures are rapidly reaching the upper limit of biologically tolerable levels and an increase in reports of ice-ice and pest outbreaks is attributable to these shifts of environmental parameters. Nevertheless, few reports on the response of eucheumatoids to a changing environment, in particular global warming, are available. Understanding the responses and possible mechanisms for acclimation to warming is crucial for a sustainable seaweed cultivation industry. Here, the physiological and biochemical responses of K. alvarezii to acute warming indicated that the strain used in the current study is unlikely to survive sudden increases in temperature above 36°C. As temperature increased, the growth rates, photosynthetic performance, phycocolloid quality (carrageenan yield, gel strength and gel viscosity) and pigment content (chlorophyll-a, carotenoid and phycobiliproteins) were reduced while the production of reactive oxygen species increased indicating the occurrence of stress in the seaweeds. This study provides a basis for future work on long term acclimation to elevated temperature and mesocosm-based multivariate studies to identify heat-tolerant strains for sustainable cultivation.

Genetic diversity and population structure of Terapon jarbua (Forskål, 1775) (Teleostei, Terapontidae) in Malaysian waters.

A background study is important for the conservation and stock management of a species. Terapon jarbua is a coastal Indo-Pacific species, sourced for human consumption. This study examined 134 samples from the central west and east coasts of Peninsular (West) Malaysia and East Malaysia. A 1446-bp concatenated dataset of mtDNA COI and Cyt b sequences was used in this study and 83 haplotypes were identified, of which 79 are unique haplotypes and four are shared haplotypes. Populations of T. jarbua in Malaysia are genetically heterogenous as shown by the high level of haplotype diversity ranging from 0.9167-0.9952, low nucleotide diversity ranging from 0.0288-0.3434, and high FST values (within population genetic variation). Population genetic structuring is not distinct as shown by the shared haplotypes between geographic populations and mixtures of haplotypes from different populations within the same genetic cluster. The gene flow patterns and population structuring observed among these regions are likely attributed to geographical distance, past historical events, allopatric speciation, dispersal ability and water currents. For instance, the mixture of haplotypes revealed an extraordinary migration ability of T. jarbua (>1200 km) via ancient river connectivity. The negative overall value of the neutrality test and a non-significant mismatch distribution are consistent with demographic expansion(s) in the past. The median-joining network concurred with the maximum likelihood haplotype tree with three major clades resolved. The scarcity of information on this species is an obstacle for future management and conservation purposes. Hence, this study aims to contribute information on the population structure, genetic diversity, and historical demography of T. jarbua in Malaysia.

A metabolomic approach to investigate effects of ocean acidification on a polar microalga Chlorella sp.

Ocean acidification, due to increased levels of anthropogenic carbon dioxide, is known to affect the physiology and growth of marine phytoplankton, especially in polar regions. However, the effect of acidification or carbonation on cellular metabolism in polar marine phytoplankton still remains an open question. There is some evidence that small chlorophytes may benefit more than other taxa of phytoplankton. To understand further how green polar picoplankton could acclimate to high oceanic CO2, studies were conducted on an Antarctic Chlorella sp. Chlorella sp. maintained its growth rate (∼0.180 d-1), photosynthetic quantum yield (Fv/Fm = ∼0.69) and chlorophyll a (0.145 fg cell-1) and carotenoid (0.06 fg cell-1) contents under high CO2, while maximum rates of electron transport decreased and non-photochemical quenching increased under elevated CO2. GCMS-based metabolomic analysis reveal that this polar Chlorella strain modulated the levels of metabolites associated with energy, amino acid, fatty acid and carbohydrate production, which could favour its survival in an increasingly acidified ocean.

Physiological and metabolic responses of Scenedesmus quadricauda (Chlorophyceae) to nickel toxicity and warming.

An ecologically important tropical freshwater microalga, Scenedesmus quadricauda, was exposed to Ni toxicity under two temperature regimes, 25 and 35 °C to investigate the interactive effects of warming and different Ni concentrations (0.1, 1.0 and 10.0 ppm). The stress responses were assessed from the growth, photosynthesis, reactive oxygen species (ROS) generation and metabolomics aspects to understand the effects at both the physiological and biochemical levels. The results showed that the cell densities of the cultures were higher at 35 °C compared to 25 °C, but decreased with increasing Ni concentrations at 35 °C. In terms of photosynthetic efficiency, the maximum quantum yield of photosystem II (F v/F m) of S. quadricauda remained consistent across different conditions. Nickel concentration at 10.0 ppm affected the maximum rate of relative electron transport (rETRm) and saturation irradiance for electron transport (E k) in photosynthesis. At 25 °C, the increase of non-photochemical quenching (NPQ) values in cells exposed to 10.0 ppm Ni might indicate the onset of thermal dissipation process as a self-protection mechanism against Ni toxicity. The combination of warming and Ni toxicity induced a strong oxidative stress response in the cells. The ROS level increased significantly by 40% after exposure to 10.0 ppm of Ni at 35 °C. The amount of Ni accumulated in the biomass was higher at 25 °C compared to 35 °C. Based on the metabolic profile, temperature contributed the most significant differentiation among the samples compared to Ni treatment and the interaction between the two factors. Amino acids, sugars and organic acids were significantly regulated by the combined factors to restore homeostasis. The most affected pathways include sulphur, amino acids, and nitrogen metabolisms. Overall, the results suggest that the inhibitory effect of Ni was lower at 35 °C compared to 25 °C probably due to lower metal uptake and primary metabolism restructuring. The ability of S. quadricauda to accumulate substantial amount of Ni and thrive at 35 °C suggests the potential use of this strain for phycoremediation and outdoor wastewater treatment.