Primary production in streams and rivers

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Primary production in streams and rivers
River morphology and continuous estimation of primary production of phytoplankton, microphytobenthos or macrophytes in streams and rivers with low atmospheric oxygen exchange based on diurnal changes of the water oxygen concentration

Author:
Date: Michael Böhme, Boehme@gmx.de
20.01.1998 ©

What I´m looking for:

I´m especially interested in relations between river morphology and primary production of river communities. Diurnal changes of the water oxygen concentration are used for calculation of primary production and community respiration (method ODUM 1956, modified). One- or two-station-analysis is possible.
The analysis requires stream and river data sets containing:

basic morphological and hydrological data (depth, current velocity, roughness of the bottom, flow,... in dependence on different water levels),
stream or river monitoring data of oxygen concentration, water temperature, water level, (conductivity, pH,...),
meteorological monitoring data: light, (wind,...).

The temporal resolution of the river and weather data should be between 1 minute to 1 hour, water level of rivers may be up to 1 day.
Because the method demands for low atmospheric oxygen exchange compared to the community primary production and community respiration, the river should not combine the features very turbulent, very shallow, and low biomass of algae and/or aquatic plants (often in high mountain regions).

Most interesting are lowland streams and rivers around the world, all climates, all dimensions. The river monitoring station should be situated at the end of a morphologically uniform section, i.e. similar mean depth, similar mean current along the section, no important tributaries or effluents or dams or weirs within the section.

If you are interested in a fast, efficient, and highly sophisticated analysis of primary production and community respiration of your stream or river, and/or if you can provide data of this kind, do´nt hesitate to contact Boehme@gmx.de

Details

Content

Introduction
Method
What measurements are necessary ?
Model
Program
Some real world examples
What else I´m interested in ?

Inhalt

Einführung
Methode
Welche Messungen werden benötigt
Auswertemodell
Programm
Beispiele
Andere interessierende Themen

Introduction

The primary production by microphytobenthos and macrophytes on the bottom, and phytoplankton, is a main process supporting life in flowing waters (beside the import of organic matter from the catchment area). Part of the organic matter will be consumed by the autochthonous organisms themselves and by all the other bacteria, fungi, and animals of the river community for the maintenance of live, for growth, and reproduction. Another part will be exported off the river ecosystem, or accumulated into organic sediments.
Knowing the intensity and dynamic of primary production within short time scales like minutes to hours, and longer time scales like days, seasons, or years, can help to understand the flowing water ecosystem.
In waters, which are affected by human made effluents, high primary production (eutrophication) may cause serious problems affecting the river community and for human use of the water. Turak & Bickel (1994) recommend, among others, quantitative measurements of the ratio of gross primary production to community respiration as potential indicators for monitoring of recovery.

I´m especially interested in relations between river morphology and primary production of river communities.

Primary production is determined by many different abiotic and biotic variables, i.g.:

light available within the water and on the river bottom,
concentration of nutrients dissolved in the river water,
flood dynamics...(scouring of plants, water turbidity...),
slope of the river bed, nature and grain size composition of the sediments,
living trees along the river banks, which shade water surface, influence the river bottom with their roots, and falling leaves,
dead trees fallen in the river; they reduce light and current in the river, and provide substrate for algae and other organisms,
travel time of the flowing water upstream the investigated site, to enable sufficient growth of phytoplankton.
...

Especially in lowland streams and rivers primary producers, phytoplankton, submersed an emersed macrophytes may significantly change conditions for primary production:

phytoplankton may be become a major part of seston, absorbing light,
emersed and submersed macrophytes may also influence light availability, flowing conditions, and river morphology,
microphytbenthos (benthic algae) sometimes form relatively stable mats, so keeping muddy sediments on the bottom,
...

So the list above makes clear, there are narrow links between river morphology and primary production. In germany, the systematic mapping and evaluation of morphological river structures is sometimes abbreviated STRUKA (Strukturgüte-Kartierung).

Content Introduction Method Measurements Model Program Examples

Method

Primary production and respiration of a river community can be estimated by different methods. Most applied are O₂- or C¹⁴-bottle-methods, where a little part of the aquatic ecosystem is isolated in a bottle, and exposured to environmental conditions considered as similar as the natural conditions. You have full control over the bottle, but you can not exactly simulate natural conditions. So the results may be correct related to the bottle, but scaling up to the originally investigated stream or river is erroneous to an unknown extend.
In contrast, the oxygen time curve analysis, a modification of ODUM's (1956) method, has some advantages:

It does not at all alter the environmental conditions for primary producers or other organisms.
Net primary production and community respiration results can be extracted in different time scales, from minutes to hours.
You can measure continously day by day without extraordinary high costs.
...

Disadvantages: The oxygen exchange with the atmosphere is often only estimated by models. There are some dozen of reaeration models on the 'market', each made for other streams or rivers. The results differ, sometimes a lot. Another disadvantage counts only for the single station oxygen time curve analysis (1-SGA). Here the interpreting model demands for an infinitly long river section with homogenous environmental conditions upstream the monitoring station. In the real world, this means you do not know the exact borders of the system under investigation.

Content Introduction Method Measurements Model Program Examples

What measurements are necessary ?

First you need nearly continuous records of dissolved oxygen concentration (O₂), temperature, and water level. Global radiation and river water turbidity data allow further analysis. These data are accessible from automated data logging units at monitoring stations continuously measuring the water quality at many important rivers around the world. If there is still no station at your river, you should install one (help available

Boehme@gmx.de).
Second you need morphological and hydrological data from your river. Necessary morphological data are the mean depth, the slope, and the roughness of the river bed upstream the monitoring station. Often you´ll find such data at river authorities.
...

Content Introduction Method Measurements Model Program Examples

Model

Because the oxygen concentration of the river water is determined by complex interaction of several biotic and abiotic factors, you need a numerical model, which takes into account at least the most important of these factors. Under some circumstances a model as simple as that shown on the graph below might be sufficient.

Click on this figure to enlarge the graph. You´ll see basic relations between gross primary production (BPP), community respiration, reaeration, light, and resultant oxygen concentration (11 KByte).

Content Introduction Method Measurements Model Program Examples

Program

To hold and manage the monitoring data, there was built an individual BASIC-program. It was especially desined to simplify and to speed up some repetitive steps necessary to handle and prepare row data:

import of ASCII-files from monitoring stations,
compact data storage: 1 file per [year, station and parameter] with 2 byte per individual value, e.g. one time series of oxygen data from January until December for a Spree-station with values every minute takes 1 MB/file, with values every hour 18 KB/file,
graphically controlled tool to eliminate runaways (e.g. occuring during cleaning of oxygen probes) or obviously incorrect parts of the time series, interpolation of short gaps (I do´nt know commercial software with comparable abilities),
calculation of hourly (or other interval) averages before P and R calculation
determination of daily minima and maxima, daily averages, medium diurnal curves of homogenous time intervalls
calculation of atmospheric oxygen exchange and net community activity within short intervals (minutes to hours, often 0.25 to 1 h)
calculation of daily values of net and gross primary production and community respiration

All calculations were performed over the entire year or shorter periods. Some other features: marking of days, which should be excluded from calculations (e.g. days, where the diurnal curve is deformed by processes not included in the model), calculation of reaeration coefficients (6 different models) dependent on different water levels for individual rivers, series printing of hardcopies of entire years even with 1 min time resolution with highest printer resolution (e.g. to document the row data quality).

Content Introduction Method Measurements Model Program Examples

Some real world examples

Three examples show different time curves of oxygen and other parameters measured in lowland streams and rivers around Berlin, germany.

Click on this symbol to load a figure showing diurnal curves of River Spree, germany, during 4 days. Parameters are oxygen, temperature, pH, fluorescence, and light (20 KByte).
Click on this symbol to load a figure showing seasonal variations of oxygen concentration of River Spree (13 KByte).
Click on this symbol to load a figure showing the highest diurnal oxygen peak I have ever seen (9 KByte).

Content Introduction Method Measurements Model Program Examples

What else I´m interested in ?

(submersed) macrophytes and their importance for ecosystem primary production and matter retention, see my search for examples,
mapping of macrophytes (especially Characeae), kite and balloon based aerial photography, diving,
other structures supporting retention of matter of all kind in aquatic ecosystems,
systematic mapping and evaluation of morphological structures of streams and rivers (STRUKA),
Central European lowland streams and rivers all are modified by human activity. I search for the "real" natural state of these flowing waters. This is a state, which would exist, when man would never had altered landscapes at all. Knowledge would help in
restoration of natural river morphology.

Content Introduction Method Measurements Model Program Examples

Michael Böhme, Boehme@gmx.de

	Primary production in streams and rivers River morphology and continuous estimation of primary production of phytoplankton, microphytobenthos or macrophytes in streams and rivers with low atmospheric oxygen exchange based on diurnal changes of the water oxygen concentration
Author: Date:	Michael Böhme, Boehme@gmx.de 20.01.1998 ©