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The harmful algal bloom species Prymnesium parvum has caused millions of dollars in damage to fisheries around the world. These fish kills have been attributed to P. parvum releasing a mixture of toxins in the water. The characterized toxins, reported as prymnesin-1 and -2, have structural similarities consistent with other known ionizable compounds (e.g.,(More)
This review discusses the interface between two of the most important types of interactions between species, interspecific competition and predation. Predation has been claimed to increase, decrease, or have little effect on, the strength, impact or importance of interspecific competition. There is confusion about both the meaning of these terms and the(More)
Models are examined in which two prey species compete for two nutrient resources, and are preyed upon by a predator that recycles both nutrients. Two factors determine the effective relative supply of the nutrients, hence competitive outcomes: the external nutrient supply ratio, and the relative recycling of the two nutrients within the system. This second(More)
A model for two competing prey species and one predator is formulated in which three essential nutrients can limit growth of all populations. Prey take up dissolved nutrients and predators ingest prey, assimilating a portion of ingested nutrients and recycling or respiring the balance. For all species, the nutrient contents of individuals vary and growth is(More)
Prymnesium parvum is a haptophyte alga that forms toxic, fish-killing blooms in a variety of brackish coastal and inland waters. Its abundance and toxicity are suppressed by ammonium additions in laboratory cultures and aquaculture ponds. In a cove of a large reservoir (Lake Granbury, Texas, USA) with recurring, seasonal blooms of P. parvum, ammonium(More)
Prymnesium parvum is a harmful alga whose blooms can cause fish kills in brackish waters. Two potential suppressants of this alga were tested, ammonium and barley straw extract (BSE), at temperatures of 10, 20 and 30 degrees C. Laboratory batch cultures were grown for 3 weeks at each temperature, with weekly doses of ammonium or BSE at either low or high(More)
A model for prey and predators is formulated in which three essential nutrients can limit growth of both populations. Prey take up dissolved nutrients, while predators ingest prey, assimilate a fraction of ingested nutrients that depends on their current nutrient status, and recycle the balance. Although individuals are modeled as identical within(More)
Species-area relationships have been observed for virtually all major groups of macroorganisms that have been studied to date but have not been explored for microscopic phytoplankton algae, which are the dominant producers in many freshwater and marine ecosystems. Our analyses of data from 142 different natural ponds, lakes, and oceans and 239 experimental(More)
We examine what circumstances allow the coexistence of microorganisms following different nutritional strategies, using a mathematical model. This model incorporates four nutritional types commonly found in planktonic ecosystems: (1) heterotrophic bacteria that consume dissolved organic matter and are prey to some of the other organisms; (2) heterotrophic(More)