Tropical Oceanographic Research Frontiers

Recent Advances in Marine Nitrogen Cycling: From Diazotrophy to Denitrification

Chinedu Okafor, Aisha Bello — Mon, 09 Feb 2026 00:00:00 +0000

Marine nitrogen cycling plays a critical role in regulating ocean productivity, biogeochemical fluxes, and the global carbon cycle. This mini-review synthesizes recent advances in understanding nitrogen transformations, from fixation by diverse diazotrophs to losses via denitrification, anammox, and DNRA, highlighting their ecological and biogeochemical significance. Recent studies have revealed the complex interactions between microbial communities and environmental drivers, including nutrient availability, oxygen minimum zones, stratification, and climate-induced warming. Technological innovations such as metagenomics, metatranscriptomics, proteomics, autonomous sensors, and compound-specific isotope analysis have provided unprecedented insights into nitrogen cycling dynamics, allowing high-resolution spatial and temporal assessments. The review also emphasizes the impacts of anthropogenic stressors, including eutrophication, pollution, and emerging contaminants like microplastics, on nitrogen fluxes and microbial function. Despite these advances, substantial uncertainties remain regarding global nitrogen budgets, the ecology of understudied diazotrophs, and the long-term responses of nitrogen cycling processes to climate and human pressures. Future research priorities include expanding long-term autonomous observations, integrating microbial process rates into biogeochemical and Earth system models, and investigating interactions with emerging pollutants. Improved understanding of these processes is essential for accurately predicting ocean productivity, carbon sequestration, and feedbacks to climate change. Collectively, this review underscores the need for interdisciplinary approaches that combine molecular biology, biogeochemistry, and advanced observational technologies to resolve key knowledge gaps and enhance our capacity to manage and predict the functioning of marine nitrogen cycles in a rapidly changing ocean environment.

Microplastics and Pollution in Indonesia’s Marine Environment: Oceanographic Perspectives

Ahmad Pratama Wijaya, Olufemi Adekunle Balogun, Neema Rehema Mkwawa — Sun, 01 Mar 2026 00:00:00 +0000

Microplastic pollution is an emerging global concern due to its persistence, ubiquity, and potential ecological and socioeconomic impacts. Indonesia, as the world’s largest archipelagic nation with extensive coastlines, diverse ecosystems, and high population density, is particularly vulnerable to marine microplastic contamination. This review synthesizes recent research on the sources, distribution, ecological consequences, and human and socioeconomic implications of microplastics in Indonesian waters, highlighting research gaps and future directions. Microplastic inputs originate from land-based sources, including domestic waste, urban runoff, rivers, tourism, aquaculture, and fisheries, as well as sea-based sources, such as fishing gear, shipping, coastal industries, and offshore aquaculture. Their transport is influenced by hydrodynamic processes, including tides, currents, monsoonal winds, and the Indonesian Throughflow, leading to spatial and seasonal heterogeneity in surface waters, sediments, and biota. Ecological impacts include ingestion by fish and invertebrates, trophic transfer, and interaction with chemical pollutants such as heavy metals and persistent organic pollutants, posing risks to marine biodiversity and ecosystem functioning. Human and socioeconomic consequences arise from seafood contamination, health risks, fisheries and aquaculture productivity losses, and impacts on tourism. Significant research gaps remain, including regional bias towards western Indonesia, lack of standardized sampling and polymer identification methods, limited integration of oceanographic modeling, and insufficient long-term and interdisciplinary studies. Future research should integrate oceanographic, ecological, and socio-economic approaches, leverage remote sensing, modeling, and molecular identification technologies, and support policy and management strategies to mitigate pollution. This review provides a comprehensive synthesis to guide future research, monitoring, and sustainable management of microplastic pollution in Indonesia’s marine environment.

The Effect of Submersible Light Attractors on Tidal Trap Fisheries: Implications for Length at Maturity

Mon, 09 Feb 2026 00:00:00 +0000

This study examined the impact of Submersible Light Attractors (SAL) on catch composition and Length at Maturity (Lm) of fish in tidal trap (gombang) fisheries in the Bengkalis Strait, Indonesia. Tidal traps, which are passive and static fishing gear, often capture undersized fish, posing a threat to the sustainability of fish stocks. The use of SAL aimed to improve catch efficiency and selectively target mature fish, thereby enhancing fishery management. The experiment compared catch composition and Lm between two fishing treatments: one with SAL (P1) and one without SAL (P0). The results showed a 17.5% increase in total catch weight when SAL was used, with significant improvements in catch size, particularly for demersal and pelagic fish species. The study indicated that SAL not only increased catch quantity but also enhanced gear selectivity, thereby reducing the bycatch of immature fish. These findings underscore the role of SAL in promoting sustainable fishing by improving catch size distribution and supporting fish population conservation. The use of SAL was recommended as a cost-effective tool for enhancing the ecological and economic viability of small-scale fisheries.