Macrophytes on Spring Creeks
by
Eugene P. Macri Jr.
Aquatic and Environmental Scientist

Macrophytes on spring creeks control patterns, cycles, sedimentation, nutrient dynamics and habitat requirements whether these streams are English Chalk Streams or Pennsylvania Limestone Springs. These include all of the following:

Macrophytes control the water flow patterns. These flow patterns are controlled to the point that if stream work is done in restructuring without consideration for these patterns it can have dire consequences for the stream in channel geomorphology. For instance, if masses of macrophtyes appear in sections of the stream they can completely reverse any flow patterns made by so called stream improvement methods. The failure to understand the role of these plants will lead to continual failure on these streams just as it has in the past.
Macrophytes furnish substrate for aquatic invertebrates. Depending upon the type of plant many macrophytes furnish the microhabitat for aquatic invertebrates including mayflies, caddisflies etc. They also furnish habitat for the fish. There is a debate on how much of the macrophyte community should be maintained on English Chalkstreams.

Macrophytes absorb and release nutrients, toxins and chemicals from the stream. Studies have shown that various submerged macrophytes are different in how they cycle nutrients and in their decompostion patterns. In some streams aquatic macrophytes load large quantities of Nitrogen and Phosphorous and hold these nutirients til they are released rapidly in Autumn. (The Photo shows an English Riverkeeper plying his trade on an English Chalk Stream).

The following is from the University of London Staff: The Role of Biotic Processes in the Sediment and Nutrient Dynamics of Lowland Permeable Streams: Implilcations for River Bed Patches:

• "Lowland permeable rivers receive terrestrial inputs of inorganic and organic matter originating from catchment run-off, erosion of river banks, re-suspension of river bed deposits and upwelling from shallow ground waters. Organic matter is also produced within streams, for example, by plant growth and senescence.
• Submerged macrophytes and their attached suspension feeders are characteristic of chalk stream ecosystems. They are typically abundant and act as ecosystem engineers. Macrophytes trap suspended (Notice the English Stream Workers. Does this stream look any different than Big Spring) matter (and associated nutrients) within their stands and the suspension feeders produce faecal pellets, compacted aggregates of organic and inorganic matter, that are transported downstream from the site of production.
• The interactions between flows, sediments, plants (and their associated animals) in rivers has implications for patch dynamics. As submerged macrophytes grow,flow is directed into areas between the dense stands and this results in patchiness in the flow patterns and alter velocity, sediment characteristics, river bed geomorphology and ecology within streams. Furthermore, the trapping and retention of suspended matter, including faecal pellets, by macrophytes has consequences for nutrient cycling within rivers. It is likely that the organic-rich sediment trapped within macrophyte stands will have nutrient dynamics that are very different to those in adjacent, unvegetated patches.(The above photo shows Ranuculus and gravel in a stream bed. Similar macrophyte communites are found in our spring creeks)
• Although the basic interactions between sediments, river flows and biota in streams have been conceptualised (Madsen et al., 2001), there is a pressing need for more field-based studies in streams and rivers to complement existing laboratory research and work in estuarine and marine environments. And the role of biotic processes in the trapping of suspended matter, and the storage and resuspension of fine sediments in rivers needs to be considered in understanding in-stream sediment (and nutrient) dynamics and budgets."

One of the problems in understanding macrophtyes effects on streams is the fact that macrophytes can absorb nutrients from both the water column and sediments. Studies in English Chalk Streams have shown great variability from river to river on how the dynamics of the cycles work. It should also be noted that macrophytes can have an influence beyond just nutrient cycling. For example, macrophytes can provide substrates for epiphytes. These epiphytes which can take up large quanities of many nutirients and influence bacteria which are involved in the Nitrogen Cycle.

Macrophytes influence and often control the water column in spring creeks by raising the water level in enitre stretches. This is one of the problems in Big Spring because in some areas the submerged macrophytes have not come back. There is now a lack of fish habitat in some areas.

The key to understanding spring creeks like Big Spring are in the macrophytes since they control most of the stream dynamics. However, the PFBC and the DEP seemto lack any serious understanding of these important plants and thus any plan which fails to address them will continue in this pseudoscience that both agencies engender and most likely have major negative impacts on Big Spring brook trout populations and the biotic community.