Water properties in the Suva Lagoon, Fiji

The salinity, temperature and turbidity in the lagoon are some important parameters for water quality which are continuously changing with the seasons and need to be studied because they are efficient indicators of variations in the lagoon and can transform the marine ecosystem. Results obtained showed that the salinity near the head of Laucala Bay during the wet-warm season was below 24.8 psu and was 33.7 psu during the drycool season. The temperature range for the Suva Lagoon during the wet-warm season was between 28.0–30.5 °C and between 24.5–25.5 °C during the dry-cool season. The turbidity in the lagoon was always above 3.0 FTU near the river mouths. The model salinity distribution compared well with the observed distribution from field data after the model was validated for salinity distribution

Contrasting the flavors of ENSO and related trends in the tropical Pacific Ocean in recent decades

The main features of the Eastern (EP) and Central (CP) Pacific El Niño Southern Oscillation (ENSO) events are analyzed using 1950-2010 observed and modeled data. Using various analysis techniques, we found that the CP El Niño differs from the canonical EP El Niño in terms of amplitude and location of maximum/minimum sea surface temperature, sea surfacesalinity and sea level anomalies, and the recharge/discharge (R/D) dynamical mode. The distinctive R/D features are characterized by different transport mechanisms: during EP El Niño, there is a mass discharge of warm waters (>20°C) over the entire equatorial band resulting in a change from El Niño to La Niña conditions. Whereas during CP El Niño, there is a compensating effect ensuing in relatively no overall discharge. Furthermore, the longterm trends due to ENSO are mostly because of the influence of CP El Niño, which for example, accounts up to 30% of the warming/freshening trends in the western-central equatorial Pacific

Capacity building of sea level and climate monitoring in the Pacific region: Fiji case study

In order to enhance capacity building in the Pacific region, and to raise awareness on climate change and sea level issues, teaching and training modules were made available to the Pacific community through the “South pacific sea level and climate monitoring project” funded by AusAID. Numerous training workshops have been conducted through the project since its inception in 1991 and the project is now in its fourth and final phase. It was hoped that the goals of capacity building for the stakeholders on correct information of climate change and sea level have been understood and taken heed of. In addition, “The scientific educational resources and experience associated with the deployment of Argo” (SEREAD) project was also set up especially for ocean science in the Pacific island schools in 2001. However, it has been realized that the data from this project is more relevant to tertiary level rather than to secondary level students. Consequently, a survey was carried out to gauge the students’ outlook towards the physical side of marine science. The survey revealed that more than 80% of both tertiary level and high school non-physical science students decided not to take the physical aspect of marine science sighting reasons that it is either a difficult subject, boring, too hard to understand or difficult to pass in the examination. Even amongst students taking physical science, only about 50% believe that the physical aspect of marine science is enjoyable. A minority of students at USP and high school take science as a subject and a small proportion from them take the physical science. From this scenario, it can be predicted that there will be a shortage of physical science graduates in the future. The confidence of the Pacific community in the work of scientists is built on faith. They appreciate the effect of science on their lives and support it but are unaware of the scientific methods involved. Therefore, for the sustainability of physical aspect of marine science in the future for the Pacific region, public awareness of climate change and sea level is vitally important and it should be widely promoted in the community as a matter of urgency

Trace metal content in sediment cores and seagrass biomass from a tropical southwest Pacific Island

A unique feature of seagrass among other ecosystem services is to have high phytoremediation potential that is a cost-effective plant-based approach and environmentally friendly solution for metal contamination in coastal areas. The goal of this study was to assess the phytoremediation prospective of seagrass for Cu, Fe, Mn and Zn in Fiji Islands. Heavy metal content was measured in sediments and tissues of the seagrasses Halophila ovalis, Halodule pinifolia and Halodule uninervis to test for local-scale differences. The local study shows that metal concentration in sediment and seagrass tissue was significantly variable, regardless of species and sediment type. Sedimentary concentration of Cu, Fe, Mn and Zn obtained in the present study seemed to be lower than that of previous studies. The results support that H. ovalis is a good bioindicator species since it accumulated up to 5-fold more of these metals compared to the Halodule species

Automatic detection of optical signatures within and around floating Tonga - Fiji pumice rafts using MODIS, VIIRS, and OLCI Satellite Sensors

An underwater volcanic eruption off the Vava’u island group in Tonga on 7 August 2019 resulted in the creation of floating pumice on the ocean’s surface extending over an area of 150 km2. The pumice’s far-reaching effects from its origin in the Tonga region to Fiji and the methods of automatic detection using satellite imagery are described, making it possible to track the westward drift of the pumice raft over 43 days. Level 2 Moderate Resolution Imaging Spectroradiometer (MODIS), Visible Infrared Imaging Radiometer Suite (VIIRS), Sentinel-3 Ocean and Land Color Instrument (OLCI), and Sentinel-3 Sea and Land Surface Temperature Radiometer (SLSTR) imagery of sea surface temperature, chlorophyll-a concentration, quasi-surface (i.e., Rayleigh-corrected) reflectance, and remote sensing reflectance were used to distinguish consolidated and fragmented rafts as well as discolored and mesotrophic waters. The rafts were detected by a 1 to 3.5 °C enhancement in the MODIS-derived “sea surface temperature” due to the emissivity difference of the raft material. Large plumes of discolored waters, characterized by higher satellite reflectance/backscattering of particles in the blue than surrounding waters (and corresponding to either submersed pumice or associated white minerals), were associated with the rafts. The discolored waters had relatively lower chlorophyll-a concentration, but this was artificial, resulting from the higher blue/red reflectance ratio caused by the reflective pumice particles. Mesotrophic waters were scarce in the region of the pumice rafts, presumably due to the absence of phytoplanktonic response to a silicium-rich pumice environment in these tropical oligotrophic environments. As beach accumulations around Pacific islands surrounded by coral shoals are a recurrent phenomenon that finds its origin far east in the ocean along the Tongan trench, monitoring the events from space, as demonstrated for the 7 August 2019 eruption, might help mitigate their potential economic impacts

Tropical cyclone climatology, variability, and trends in the Tonga region, Southwest Pacific

The focus of several past tropical cyclone (TC) studies in the Southwest Pacific (SWP) had been primarily at the regional scale, with little or no attention to the local-scale TC activity (i.e., at the country level). With the growing coastal population in the South Pacific Island countries, as well as increasing threats from and exposure to climate extremes mostly affecting vulnerable communities, examining TC-related risks at the country level is more imperative now than before. This study catalogues for the first time the climatology, variability and trends of TCs affecting Nuku'alofa, the capital of Tonga using the Southwest Pacific Enhanced Archived for Tropical Cyclone (SPEArTC) dataset for the period between 1970 and 2019. The variability is examined in relation to the El Niño–Southern Oscillation (ENSO) phenomenon, which is the major driver of the year-to-year variability of TC activity in the SWP. A total of 128 TC tracks affected the Tonga region over the study period, with a seasonal average of ∼2.6 TCs per year. Of these, about 50% occurred during the peak months of January and February, and ∼38.8% of the total were of hurricane intensity (Categories 3, 4 and 5). Although differences were found between the average number of TCs per year during El Niño, La Niña and ENSO-neutral events (∼2.9, ∼2.6 and ∼2.3, respectively), they were statistically insignificant. No significant long-term trends were found in the number of TCs, severe TCs, and accumulated cyclone energy (ACE) over the period of study. The findings of this study will provide the information needed for disaster preparedness and TC predictions in Tonga

Increasing biomass in the warm oceans: unexpected new insights from SeaWiFS

Marine phytoplankton biomass and community structure are expected to change under global warming, with potentially significant impacts on ocean carbon, nutrient cycling, and marine food webs. Previous studies have indicated decreases of primary production and chlorophyll a concentrations and oligotrophic gyre expansions from satellite ocean‐color measurements, purportedly due to global warming. We review this topic via a reanalysis of a novel backscattering‐based phytoplankton functional type and phytoplankton biomass time series over the 1997–2010 period. Unlike previous work, we find that globally the biomass and the percent of large (small) phytoplankton increase (decrease). The oligotrophic gyres contract or expand depending on the chlorophyll a threshold definition employed. In the subtropical gyres, chlorophyll a trends are likely due to physiological changes, while the increasing biomass trends are due to winds and relevant mixing length scale increases

Impact of ashes from the 2022 Tonga volcanic eruption on satellite ocean color signatures

A powerful eruption within the Hunga Tonga-Hunga Ha’apai (HTHH) volcano (20.64°S, 175.19°W) in the Kingdom of Tonga, occurred on 15 January 2022. The volcanic blast was enormous, leading many scientists to investigate the full impact and magnitude of this event via satellite observations. In this study, we describe a new ocean color signature from a discolored water patch created by the HTHH eruption using NASA and CMEMS products of satellite-derived biological and optical properties. Elevated surface chlorophyll-a concentration (Chl-a) between 0.15 to 2.7 mg.m-3 was not associated with phytoplankton growth, but to basalt-andesitic ash material expelled by the volcano and into the ocean, which resulted in erroneous Chl-a estimates. Distribution of the patch over time was aligned with CMEMS ocean currents for 19 days. The gradual decrease of light attenuation or diffuse attenuation coefficient for downward irradiance at 490 nm, Kd(490), was interpreted as due to the sinking of ash particles with time. It is suggested that due to high porosity of 30-40%, a density close to that of seawater, ash particles stay suspended in the water column for more than 10 days with sustained high values of satellite-derived Chl-a, Kd(490), and particulate backscattering coefficient at 443 nm. The high attenuation of light due to ash, reducing the penetration depth to less than 10 meters during the first period after the eruption may have had implications on ecological processes and biogeochemical cycles in Tongan waters

Transnational distance learning: a student perspective

This chapter describes the online educational experiences of students in both emerging and developed countries around the world. The authors are from France, Japan, India, Cyprus, Canada, the United States, and Fiji. This cross-section was chosen to present a global view of student needs for transnational education. The chapter presents personal vignettes of the online educational experiences, as well as the authors’ views of student needs in the future. The authors also describe how they used technology to coordinate writing this chapter from six countries around the world

Understanding ecosystem services for climate change resilience in coastal environments: a case study of low - canopy sub - tidal seagrass beds in Fiji

The Pacific Island Countries (PICs) are exposed to extreme wave conditions which are projected to be exacerbated by rising sea levels due to climate change, prompting the need for strategic planning of coastal communities and assets. Nature-based protection has been proposed as a sustainable solution to promote the resilience of coastal areas from physical impacts such as wave-induced erosion. In this study, we investigate the potential coastal protection service of shallow sub-tidal low-canopy seagrass beds, dominated by Halodule uninervis, on the rate of wave height and wave energy reduction on a barrier and fringing reefs. The data was collected using bottom-mounted pressure sensors to measure wave height and energy reduction as waves moved toward the shoreline across the seagrass beds. The results show that on average, the seagrass beds were able to reduce wave height by 30% and energy by 47% in both reef environments. These reduction rates are strongly influenced by water depth, seagrass characteristics and local reef conditions. Based on these results, seagrasses can strengthen the resilience of coastal shorelines to wave erosion, thus conserving healthy low-canopy seagrass habitats has measurable benefits for shoreline protection in Fiji and other PICs