Freshwater Spring Introduction 

Freshwater Springs 
as Model Systems  

Further Background

Springs are formed where underground water surfaces through rock faults or fractures to form a brook (rheocrene), pond (limnocrene), or marsh (helocrene).  Springs are unique freshwater habitats because their physical and chemical environments are usually nearly constant.  Persistent springs never freeze over, and large ones maintain remarkably constant temperatures throughout the year. These and other advantageous properties make springs excellent natural laboratories for studying the ecology and evolution of species and biotic communities (Glazier, 1998; Williams and Williams, 1998), as attested by the following quotations from two leading biologists: 

“Springs are the aquatic ecologist’s natural constant temperature laboratory.  Because of the relative constancy of the chemical composition, velocity of water, and temperature, in comparison with lakes, rivers, marine environments, and terrestrial communities, springs hold a position of importance as study areas that is out of proportion to their size and number.”  (E.P. Odum, 1971) 

“It would seem … that springs may offer almost ideal sites for evolutionary genetic studies, especially in glaciated areas where their ages can be fairly accurately known.”  (H.B.N. Hynes, 1970) 
 

 

Specific advantages of springs include:  

• The constant temperature of springs allows field work to be carried out year-round, despite marked seasonal changes in the “outside world”. 

• The remarkably constant temperatures and water chemistry of springs simplify the interpretation of field research and the establishment of field conditions in the laboratory. 

• Springs may differ significantly in habitat (e.g., substrate, amount of aquatic vegetation, and degree of shading by springside vegetation), water chemistry (e.g., pH and ionic content), and biotic composition (e.g., presence or absence of specific competitors, predators and/or parasites), thus constituting useful “natural experiments”. 

Cold Spring  (an acidic, soft water spring)

Griffith Spring  (a watercress-choked spring)

• Springs are typically small, discrete habitats, usually with relatively few common species, thus simplifying population, community and ecosystem analyses. 

• Many springs have clear, shallow, slow-moving water, thus facilitating collection of organisms, behavioral studies, and transplant and enclosure experiments and their observation. 

 

• Environmental gradients along the length of springbrooks are useful for investigating the effects of environmental variation (e.g., temperature) on living systems.

• Springs are directly connected to groundwater and/or cave environments, and thus are useful for monitoring the quality of groundwater, and for comparing the adaptations of surface and subterranean life.

• Large springs may have a mosaic of habitats suitable for studies of habitat selection (e.g., Gooch and Glazier, 1991).  Microhabitat stability is made possible by nearly constant flow rates.  As can be seen in the photographs below, a summer rainstorm causes great increases in the water and sediment flow of run-off streams, whereas the flow rate and water clarity of spring-fed streams are little affected. 

Crooked Creek (A)

Bouquet Springbrook (B)

Because of these advantageous properties, several noteworthy ecological studies have been carried out in springs.  For example, 
springs have been used as model ecosystems to study productivity, energy flow and trophic relationships (e.g., Odum, 1957; Teal, 1957; Minckley, 1963; Minshall, 1967; Tilly, 1968; Iversen, 1988).  Nevertheless, springs remain relatively neglected as subjects of ecological and evolutionary study.  Little comparative work has been done on North American springs (e.g., Glazier & Gooch, 1987; Webb et al., 1995; Williams, Williams & Cao, 1997; Erman, 1998); and little is known about why the biotas of springs are often markedly different from those of downstream sites and of run-off supplied headwater streams (Glazier, 1991). 

Springs and their inhabitants also appear to have been little used as tools to teach students basic ecological and evolutionary ideas and methodologies, despite their being well-suited for this purpose.  It is hoped that this web page will help to stimulate others to use springs as both educational and research systems. 

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