Kurtz Bruce E, Landmeyer James E, Culter James K
New College of Florida, 5800 Bay Shore Rd., Sarasota, FL 34243, USA.
U. S. Geological Survey, 4446 Pet Ln Ste 108, Lutz, FL 33559, USA.
Heliyon. 2023 May 6;9(5):e16046. doi: 10.1016/j.heliyon.2023.e16046. eCollection 2023 May.
Blooms of the dinoflagellate occur almost every year along the southwest Florida Gulf coast. Long-duration blooms with especially high concentrations of , known as red tides, destroy marine life through production of neurotoxins. Current hypotheses are that red tides originate in oligotrophic waters far offshore using nitrogen (N) from upwelling bottom water or, alternatively, from blooms of , followed by advection to nearshore waters. But the amount of N available from terrestrial sources does not appear to be adequate to maintain a nearshore red tide. To explain this discrepancy, we hypothesize that contemporary red tides are associated with release of N from offshore submarine groundwater discharge (SGD) that has accumulated in benthic sediment biomass by dissimilatory nitrate reduction to ammonium (DNRA). The release occurs when sediment labile organic carbon (LOC), used as the electron donor in DNRA, is exhausted. Detritus from the resulting destruction of marine life restores the sediment LOC to continue the cycle of red tides. The severity of individual red tides increases with increased bloom-year precipitation in the geographic region where the SGD originates, while the severity of ordinary blooms is relatively unaffected.
在佛罗里达州西南部墨西哥湾沿岸，每年几乎都会出现甲藻大量繁殖的现象。持续时间较长且含有特别高浓度（某种物质，原文未明确写出）的水华，即所谓的赤潮，会通过产生神经毒素来破坏海洋生物。目前的假说认为，赤潮起源于离岸较远的贫营养水域，利用上升流底层水中的氮（N），或者起源于（某种藻类，原文未明确写出）的大量繁殖，随后平流至近岸水域。但是来自陆地来源的可用氮量似乎不足以维持近岸赤潮。为了解释这种差异，我们推测当代赤潮与近海海底地下水排放（SGD）中氮的释放有关，这些氮通过异化硝酸盐还原为铵（DNRA）在底栖沉积物生物量中积累。当用作DNRA中电子供体的沉积物不稳定有机碳（LOC）耗尽时，就会发生这种释放。海洋生物被破坏产生的碎屑会恢复沉积物中的LOC，从而继续赤潮循环。在SGD起源的地理区域，个别赤潮的严重程度会随着水华年份降水量的增加而增加，而普通水华的严重程度相对不受影响。
