Details

Autor(en) / Beteiligte

• Shetye, Suhas
• Pratihary, Anil
• Shenoy, Damodar
• Kurian, Siby
• Gauns, Mangesh
• Uskaikar, Hema
• Naik, Bhagyashri
• Nandakumar, K.
• Borker, Sidhesh

Titel

Rice husk as a potential source of silicate to oceanic phytoplankton

Ist Teil von

• The Science of the total environment, 2023-06, Vol.879, p.162941-162941, Article 162941

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2023

Quelle

MEDLINE

Beschreibungen/Notizen

• Global oceans are witnessing changes in the phytoplankton community composition due to various environmental stressors such as rising temperature, stratification, nutrient limitation, and ocean acidification. The Arabian Sea is undergoing changes in its phytoplankton community composition, especially during winter, with the diatoms being replaced by harmful algal blooms (HABs) of dinoflagellates. Recent studies have already highlighted dissolved silicate (DSi) limitation and change in Silicon (Si)/Nitrogen (N) ratios as the factors responsible for the observed changes in the phytoplankton community in the Arabian Sea. Our investigation also revealed Si/N < 1 in the northern Arabian Sea, indicating DSi limitation, especially during winter. Here, we demonstrate that rice husk with its phytoliths is an important source of bioavailable DSi for oceanic phytoplankton. Our experiment showed that a rice husk can release ∼12 μM of DSi in 15 days and can release DSi for ∼20 days. The DSi availability increased diatom abundance up to ∼9 times. The major benefitted diatom species from DSi enrichment were Nitzshia spp., Striatella spp., Navicula spp., Dactiliosolen spp., and Leptocylindrus spp. The increase in diatom abundance was accompanied by an increase in fucoxanthin and dimethyl sulphide (DMS), an anti-greenhouse gas. Thus, the rice husk with its buoyancy and slow DSi release has the potential to reduce HABs, and increase diatoms and fishery resources in addition to carbon dioxide (CO2) sequestration in DSi-limited oceanic regions such as the Arabian Sea. Rice husk if released at the formation site of the Subantarctic mode water in the Southern Ocean could supply DSi to the thermocline in the global oceans thereby increasing diatom blooms and consequently the biotic carbon sequestration potential of the entire ocean. [Display omitted] •Rice husk which can release ∼15 µM silicate in ∼ 20 days is a good source of silicate for diatoms in slicate-depleted regions•Silicate limitation was observed in the northern Arabian Sea during winter•Long term data showed rise in nitrogen rather than drop in silicate that has reduced the Si/N•Silicate supplied via rice husk supported high abundance of diatoms•This study provides a new method to reduce harmful algal blooms