Rapid profiling of tropical marine cyanobacterial communities

Cyanobacteria are important organisms in the marine ecosystem as they play vital roles in nutrient cycling and oxygen production. In this study, tropical marine cyanobacterial communities from various sites in Southeast Asia and their associated ecological parameters were examined. 16S rRNA sequences of 1502 bp were obtained for barcode amplicon sequencing using the Nanopore MinION™ sequencing platform. Planktonic and benthic cyanobacteria were observed with total of 40 genera and 46 species of cyanobacteria identified from sites in Sabah and Singapore. Species richness analyses showed that the cyanobacterial community from the West Johor Strait was approximately two times greater than that of the East Johor Strait and the Singapore Strait. This is due to the variability in ecological parameters measured between sites such as rainfall, salinity and temperature. This is the first study that has employed this technology for phytoplankton samples with species resolution, providing insight to the diversity of cyanobacteria present in tropical marine ecosystems. Furthermore, the portability of this sequencer enables the real-time monitoring of coastal environments for the specific detection and identification of harmful algal bloom species

Characterization of the phytoplankton size composition and light absorption coefficient in the temperate coastal waters of Sagami Bay

Phytoplankton constitute the base of the aquatic food web and are the primary driver of biogeochemical processes such as the e port of carbon to the deep ocean. Knowledge of the distributions, compositions, and biomass of the phytoplankton community are essential to under stand biogeochemical cycles. Phytoplankton can be enumerated by microscopy, but this requires e tensive time for sample preparation and counting, especially if statistically valid counts of the less abundant phytoplankton classes are required. Further, smaller picoplankton can be difficult to identify since they lack ta onomically e ternal morphological features. Thus, the accessory pigment-based model has been used to estimate phytoplankton communities based on their size classes: micro- (M; > 20 µm), nano- (N; 2-20 µm) and pico-phytoplankton (P; < 2 µm). Light absorption by phytoplankton has a direct influence on the optical properties of seawater, and there is a growing effort to develop approaches to identify the spatial and temporal variability of the phytoplankton community from satellites. However, estimating the phytoplankton com munity in optically comple coastal waters from satellites is still a challenging problem because phytoplankton are only one of multiple optically significant constituents of seawater. Also, there are limitations of wavelength that satellites can measure, and overlapping signature pigment of each phytoplankton community. In order to improve the estimation of phytoplankton communi ties, it is necessary to understand the light absorption coefficient of phytoplankton, aph (,,) asso ciated with the varying community structure. The objective of this study was to characterize the variability of phytoplankton size classes and their light absorption coefficients in the temperate coastal waters of Sagami Bay. The specific objectives were (1) to classify phytoplankton com munities based on cell size, (2) to investigate co-variability of aph (,,) spectra according to the classification. The present study conducted in situ observations from April 2016 to September 2022 at Station M (St. M: 35° 09’ 45” N, 139° 10’00” E) in the temporal coastal waters of Sagami Bay, Japan. Water samples for pigments and light absorption properties of phytoplankton were collected from surface water with a bucket, and measured by high-performance liquid chroma tography and spectrophotometry, respectively. Phytoplankton size class composition was esti mated based on pigment concentrations. The results showed that the three groups (Group M, N, P) generated according to the phytoplankton size composition were significantly different (R = 0.646, p < 0.001). Also, the most dominant group throughout the study period was microplank ton (n = 110). The aph (,,) spectra showed peaks around 438 nm and 465 nm in the blue band and 674 nm in the red band. Using three wavelengths peaks, although the aph (,,) of group M was sig nificantly higher than that of group N, Group P was not significantly different from other groups. This study suggests that the aph (,,) spectrum in the temperate coastal waters of Sagami Bay is significantly co-varying with the variability of phytoplankton size composition. The results sug gest that analyzing the difference in aph (,,) spectra ratios and performing derivative analysis, coupled with analysis of phytoplankton size distribution and pigment composition should im prove our ability to characterize phytoplankton spatio-temporal distribution from space.departmental bulletin pape

Practical Science and Environmental Education Workshop in Manaus, Brazil

It is an unequivocal fact that Amazonian tropical forest is the largest remaining primary forest in the world. The ecosystem in the region is e tremely comple with high biodiversity (Peres et al. 2010). Conservation and protection of the dynamic forest and river regions is e tremely important not only for the natural environments, but also for the economy and social dependence of benefits from such abundant natural environments. Important natural parameters that affect status of the natural environments include light (natural sunlight), soil, and water, which abundantly e ist in the Amazon region. Solar energy is the primary energy source for the majority of living organisms in both terrestrial and aquatic ecosystems, and drives the diurnal and seasonal cycles of biogeochemical processes (Monteith & Unsworth 2013). In particular, in situ light data remains one of the most underappreciated data measurements although having a significant impact on the physical, chemical and biological processes in the ecosystem (Johnsen 2012). Soil provides the fundamental basis for all terrestrial living organisms including the Amazonian forests as well as life-sustaining infrastructure for human society. Water is the most essential single entity to constitute all organisms from a single cell to the earth. Understanding of importance and roles of each factor and interaction of such comple dynamics in the natural environments can serve as fundamental platform for natural scientists, particularly for young scientists such as university students. The objective of this workshop was to provide hand- on scientific and environmental education for university students in Manaus, Amazonas, Brazil through practical field measurements using the three most important parameters in the natural ecosystem composed of natural sunlight, soil, and water. The workshop was divided into a series of lectures, in situ field sampling, and data processing, analysis and interpretation with the ultimate goal of empowering the undergraduate students with research-centered environmental education and e perience of developing international collaboration.departmental bulletin pape

Size-dependent absorption property of phytoplantkon in the Southern Ocean

第2回極域科学シンポジウム　共通セッション「海氷圏の生物地球化学」 11月16日（水） 統計数理研究所 3階セミナー

Marine microplastics in the ASEAN region: A review of the current state of knowledge

28811777

Primary School Children and Teachers’ Perceptions of Environmental Education in Surabaya, Indonesia

Progress of environmental education in primary schools in emerging economies has become increasingly important in recent years. This qualitative study surveyed 6^th grade children and teachers from 11 public and private primary educational institutions in Surabaya, Indonesia to determine their respective conceptions towards environmental education. The results suggest that children are highly motivated to learn mathematics, science and environmental education, but are limited in practical skills and participation opportunities. Teachers also showed strong interest in environmental education and concern for regional environmental issues, but are primarily focused on an awareness and knowledge-centered approaches with low emphasis on participation and practical skills in this region

Annual dynamics of eukaryotic and bacterial communities revealed by 18S and 16S rRNA metabarcoding in the coastal ecosystem of Sagami Bay, Japan

Sagami Bay, Japan is influenced by both the warm Kuroshio Current and the cold Oyashio Current and rich nutrients are supplied from multiple river sources and the deep-sea, forming a dynamic ecosystem. The aim of the present study was to investigate eukaryotic and bacterial communities in the coastal waters of Sagami Bay, using 16S rRNA and 18S rRNA sequencing and to assess the seasonal and vertical dynamics in relation to physicochemical and biological conditions. Eukaryotic and bacterial communities showed synchronous seasonal and vertical changes along with environmental variability. Diversity of plankton community suspended in the surface was lower than those at the subsurface layers in both the eukaryotes and bacteria communities; however, community diversity showed different characteristics in the subsurface where the eukaryotic community at the deeper layer (100 m) was as low as the surface and highest in intermediate depth layers (10–50 m), while that of bacterial community was highest in the deeper layer (100 m). The annual variability of the coastal microbial communities was driven, not only by the seasonal changes of abiotic and biotic factors and short-term rapid changes by river water inflow and phytoplankton blooms, but also largely influenced by deep-seawater upwellings due to the unique seafloor topography

Marine Microplastics in the ASEAN Region: A Review of the Current State of Knowledge

Environmental Pollution28811777

Primary School Children and Teachers’ Perceptions of Environmental Education in Surabaya, Indonesia

Progress of environmental education in primary schools in emerging economies has become increasingly important in recent years. This qualitative study surveyed 6^th grade children and teachers from 11 public and private primary educational institutions in Surabaya, Indonesia to determine their respective conceptions towards environmental education. The results suggest that children are highly motivated to learn mathematics, science and environmental education, but are limited in practical skills and participation opportunities. Teachers also showed strong interest in environmental education and concern for regional environmental issues, but are primarily focused on an awareness and knowledge-centered approaches with low emphasis on participation and practical skills in this region