Mechanisms of Competition and Coexistence in Freshwater Algae and Bacteria

[9418096] Grover不同种类的生物竞争生长所需的资源。从理论上讲，这种竞争会导致除了最优秀的竞争者之外的所有物种灭绝。淡水生境中的藻类和细菌经常争夺溶解的磷，这是一种必需的营养物质，但在大多数生境中观察到共存，尽管细菌的竞争能力更强。允许这种共存的机制目前尚不清楚，本研究将使用实验室调查来探索它们。这将通过在规定的条件下一起培养藻类和细菌来实现，识别共存的生物体，并确定它们允许共存的特性。在这些研究中需要检验的工作假设包括：(1)细菌而不是藻类需要的溶解有机碳供应不足的可能性，限制了细菌消耗磷的能力；(2)藻类和细菌专门研究不同化学形式的磷的可能性；(3)当磷供应变化时，藻类最能储存高浓度磷的可能性。而细菌在低本底浓度下获取磷的能力最强；(4)原生动物吃细菌而不吃藻类的可能性限制了细菌的生长，从而使藻类获得磷。藻类过度生长是一种常见的水质问题，而这种过度生长通常与水体接受的磷供应有关。了解藻类和细菌在获取磷方面的竞争平衡将有助于为水质管理提供科学依据。

9418096 Grover Different species of organisms compete for the resources needed for growth. Theoretically, such competition can lead to extinction of all species but the best competitor. Algae and bacteria in freshwater habitats often compete for dissolved phosphorus, an essential nutrient, but are observed to coexist in most habitats, despite the superior competitive ability of bacteria. The mechanisms that allow this coexistence are currently unknown, and this study will use laboratory investigations to explore them. This will be done by growing algae and bacteria together under defined conditions, identifying the organisms that coexist, and determining their properties that allow coexistence. Working hypotheses to be examined in these studies include (1) the possibility that lack of a sufficient supply of dissolved organic carbon, required by bacteria but not algae, limits the ability of bacteria to consume phosphorus, (2) the possibility that algae and bacteria specialize on chemically distinct forms of phosphorus, (3) the possibility that when phosphorus supply varies, algae are best able to store phosphorus acquired at elevated concentrations, while bacteria are best able to acquire phosphorus at low background concentrations, and (4) the possibility that protozoa eating bacteria, but not algae, limit the growth of bacteria, thus allowing algae to acquire phosphorus. Excessive algal growth is a common water quality problem, and such excessive growth is often related to the phosphorus supply that a body of water receives. Understanding the competitive balance between algae and bacteria in acquiring this phosphorus will help provide a scientific basis for management of water quality.