One Ocean, Many Worlds of Life - Convention on Biological Diversity

Green algal bloom make water potentially unsafe
Although the factors involved are complex—they include not just the total
amount <strong>of</strong> nutrients entering coastal waters, but also the form in which
those nutrients occur, and the ratios <strong>of</strong> nutrients such as nitrogen and
phosphorous—the correlation between nutrient pollution and increased
HABs is clear.89 For example, in the waters <strong>of</strong> Puget Sound in the northwestern
United States, there is a strong correlation between increased
records <strong>of</strong> paralytic shellfish toxins, which are produced by specific types
<strong>of</strong> din<strong>of</strong>lagellate algae, and the growth in the human population in the
region over the past four decades. Off the coast <strong>of</strong> China, harmful blooms
<strong>of</strong> some plankton species have expanded in recent years, now covering
tens <strong>of</strong> square kilometres instead <strong>of</strong> a square kilometre or two, and lasting
weeks and even months instead <strong>of</strong> days – increases that can be directly
tied to increased fertilizer use. Similar blooms, tied to similar causes, are
a feature <strong>of</strong> the Baltic, Aegean, Northern Adriatic and Black Seas, while a
five-year-study showed a strong positive relationship between nitrogen-rich
agricultural run<strong>of</strong>f to the Gulf <strong>of</strong> California and the development, within
days, <strong>of</strong> extensive phytoplankton blooms.90
When the algae die they sink to the bottom where they decompose, and the
nutrients contained in organic matter are converted into inorganic form
<strong>One</strong> <strong>Ocean</strong>, <strong>Many</strong> WOrlds Of life
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