Eutrophication Driven by Aquaculture Fish Farms Controls Phytoplankton and Dinoflagellate Cyst Abundance in the Southern Coastal Waters of Korea

Abstract

We examined the dynamics of dinoflagellate cyst and phytoplankton assemblages in eutrophic coastal waters of Korea, adjacent to fish and shellfish farms. Water temperature showed seasonality, whereas salinity and pH remained relatively consistent. Dissolved inorganic nutrient levels were higher in September and at the inner stations, where aquaculture fish farms are located than those in May and at the outer stations. Canonical correspondence analysis and artificial neural network analysis revealed multiple environmental factors that affect the distribution of phytoplankton and dinoflagellate cysts. Diatoms dominated in the phytoplankton assemblages, while the protoperidinioid group dominated in the dinoflagellate cyst assemblages. Cyst abundance was higher at the outer stations than at the inner stations due to transport by fast currents, and phytoplankton abundance was positively correlated with cyst abundance. An increase in diatom abundance led to an increase in heterotrophic/mixotrophic cyst abundance, indicating that excessive uneaten food and urinary waste from the fish farms caused eutrophication in the study region and fast growth of diatoms, thereby contributing to the growth of heterotrophic/mixotrophic dinoflagellates and consequently, high abundance of heterotrophic/mixotrophic dinoflagellate cysts.

Distribution of Dinoflagellate Cysts in Surface Sediments From the Qingdao Coast, the Yellow Sea, China: The Potential Risk of Harmful Algal Blooms

“…Therefore, the yield of cysts of autotrophic dinoflagellates should be higher than those of heterotrophs. The increased proportion of heterotrophic cysts indicates sufficient food resources for them, which has been regarded as an indicator of eutrophication (Matsuoka, 1999;Kang et al, 2021). Cyst assemblages in the Qingdao coast were dominated by cysts of autotrophic dinoflagellates with an average proportion of 76.48%, suggesting that the water quality in the Qingdao coast has not reached eutrophication level yet.…”

Recent Applications of Biopolymers Derived from Fish Industry Waste in Food Packaging

“…To overcome this problem, a high content of plasticizers (about 40–60%) is added into the biodegradable film in order to decrease the brittleness and increase the extensibility and toughness by lowering the forces between the protein–protein chains [ 49 ]. Another limit of fish myofibrillar protein films is the poor water vapor barrier, due to the high hydrophilic nature of amino acids in the proteins and to the significant amounts of hydrophilic plasticizers added, such as glycerol and sorbitol, to impart the adequate film flexibility [ 4 , 15 , 42 ]. Chemical crosslinking, electron beam and gamma radiation have been reported as effective methods for obtaining stronger and less permeable films [ 4 , 50 , 51 , 52 ].…”

“…The depletion of oxygen occurs as a result of an increased consumption of aerobic bacteria and other organisms that degrade organic wastes with tainable exploitation of marine biological resources and marine ecosystems and the financial viability of fisheries [13]. The depletion of oxygen occurs as a result of an increased consumption of aerobic bacteria and other organisms that degrade organic wastes with changes in the benthic environment [14,15]. Fish discarding, in fact, greatly affects the marine ecosystem through the food web.…”

Marine Biopolymers: Applications in Food Packaging

“…As a solution, plasticizers are recommended while producing the film [154,241]. The plasticizers lower the protein-protein interactions, improving the film's toughness, brittleness, and extensibility [242,243]. Collagen, another promising protein biopolymer, is also limited in application due to its low thermal stability and poor mechanical properties [244,245].…”