Submarine groundwater discharge-driven nutrient fluxes in a typical mangrove and aquaculture bay of the Beibu Gulf, China

An accidental encounter with bloom of diatom Palmerina hardmaniana (Greville) Hasle in Sundarbans, India: Impact on zooplankton community structure in tidal creek environment

The present study reports on a transient diatom bloom of Palmerina hardmaniana (Greville) Hasle 1996 encountered accidentally in May 2018 in the world's largest mangrove forest of Sundarbans, India. This bloom was the sixth record of diatom blooms from Indian coastal waters and the fourth from Sundarbans waters. The diatom cell count ranged from 2.571 × 104 to 6.857 × 104 cells L-1 during the bloom. The zooplankton taxa count decreased from 39 during the pre-bloom to 30 during bloom and 31 during the post-bloom phase. However, no significant (p < 0.05) change in zooplankton species richness was observed between the three different phases. The consistent occurrence of copepod Bestiolina simlis across sampling points indicated a high tolerance to environmental parameters. The zooplankton population also did not respond vehemently to bloom-forming P. hardmaniana in this creek environment. These observations warrant further studies to examine the effect of blooms on the overall marine ecological food chain of creek ecosystems.

Variations in the coral community at the high-latitude Bailong Peninsula, northern South China Sea

High-latitude coral communities have attracted much attention due to their potential as refuges during global climate change. However, this function is being constrained by the combined pressure of global climate and anthropogenic activities. To determine how the reef has developed, we conducted a long-term monitoring study on coral communities along the Bailong Peninsula in the northern South China Sea. The results showed that the distribution area of corals was 3.67 km² and that corals extended about 4.7 km along the coastline. The coral distribution pattern is scattered and uneven. Our results showed that the growth of reef-building corals and coral recruitment are improving, indicating that coral recruitment plays an important role in regulating the structure of adult coral populations and promoting the development of coral communities. Bailong Peninsula is expected to become a refuge for corals provided that human activities impacting coral restoration potential are controlled.

Tidally driven submarine groundwater discharge to a marine aquaculture embayment: Insights from radium and dissolved silicon

For understanding the significance of tidal pumping for driving submarine groundwater discharge (SGD), two time series observations were conducted over tidal cycles in typical mariculture areas of Sanmen Bay, China. Based on ²²⁴Ra and dissolved silicon (DSi), the tide-driven SGD fluxes showed significant negative correlations with tidal height, and were 16.4 ± 5.6 cm d^-1 and 21.7 ± 13.9 cm d^-1 at two coastal sites of the Sanmen Bay, highlighting the potential of DSi in SGD calculation when coastal waters are on short time scales. Furthermore, nutrient fluxes through tidally influenced SGD were estimated to be 11.5-26.5 mmol m^-2 d^-1 for dissolved inorganic nitrogen, 0.06-0.34 mmol m^-2 d^-1 for dissolved inorganic phosphorus and 11.5-32.1 mmol m^-2 d^-1 for DSi, which were higher than those from surface loadings, revealing that tide-driven SGD with large amounts of nutrient and high N:P ratios may significantly contribute to the development of marine aquaculture.