Hydrodynamics across seagrass meadows and its impacts on Indonesian coastal ecosystems: A review

Abstract

Seagrass canopies are important components of the world’s coastal environments providing critical ecological services. Nearshore hydrodynamics, i.e., waves and currents, are essential in controlling the ecological processes across coastal environments. Seagrass meadows can impose more complex hydrodynamics processes by attenuating sea-swell waves and decreasing the impact of nearshore mean water level rise due to wave setup and Infragravity (IG) waves. Consequently, the seagrasses dissipate waves and reduce flows allowing sediments to settle and accrete the shorelines. However, despite their significant roles, knowledge of hydrodynamics in the Indonesian seagrass ecosystems is relatively limited compared to other coastal ecosystems such as sandy beaches, mangroves, and coral reefs. This review highlights the dynamics of waves and currents, and their interaction with sediment transport and ecological processes, including biogeochemical and dispersal processes on the seagrass ecosystem contributing to the existing seagrass research in Indonesia. The associated literature is collected from scientific databases such as Scopus and Google Scholar that range between 1965 and 2021. The result showed that most of the research on hydrodynamic in seagrass ecosystems was carried out in temperate zones. Until recently, there have been limited publications discussing the interaction between the Indonesian (tropical) seagrass ecosystem and hydrodynamics parameters, even though the region has abundant seagrass species. Moreover, Indonesia is strongly influenced by various atmospheric-oceanic forcing, including the Asian monsoon affecting the dynamic of the coastal area with seagrass ecosystems. At a canopy scale, the correlation between the nearshore (tropical) hydrodynamics and ecological processes in the system is yet to be explored. Considering the potential benefit of seagrasses to coastal ecosystems, developing future research in hydrodynamics across the ecosystem is critical to overcoming the knowledge gaps in Indonesia. The knowledge gained could support the Indonesian seagrass ecosystem services and their resilience to potential hazards and climate change.

Sedimentary seagrass carbon stock and sources of organic carbon across contrasting seagrass meadows in Indonesia

“…The high OC content and carbon stock at the MPA site might be attributed to the composition of seagrass in the location, which is dominated by large-leaved seagrass, Enhalus acoroides (56.7%; Daulat et al 2015 ). Enhalus acoroides is known as persistent species in Indonesia with high durability against environmental pressures (Risandi et al 2023 ). Large-leaved seagrasses tend to have rhizomes and roots that are also larger and more persistent, penetrating deeper into sediment, making them more likely to be preserved in marine sediment (Lavery et al 2013 ; Trevathan-Tackett et al 2015 ; Stankovic et al, 2018 ; Kennedy et al 2022 ).…”

“…We obtained only one core in this location due to access to the seagrass meadow hindered by high waves. High wave energy environment could lower sediment deposition in the core location (Potouroglou et al 2017 ; Guerra-Vargas et al 2020 ), reduce seagrass photosynthesis efficiency due to increase bottom sediment resuspension, and might expose the already buried OC to aerobic condition (Mazarrasa et al 2018 , Risandi et al 2023 ). However, the OC in the sediment samples from this site was mostly seagrass derived (~ 60%), which was likely due to condition of the island, since it is considered pristine with little disturbance from humans and receives little or no river discharge, therefore receiving little allochthonous input.…”