The effects of browning related water chemistry variables (DOC, iron and pH) on macroinvertebrate communities across streams
(2023) BIOM02 20231Degree Projects in Biology
- Abstract
- Browning - increased water colour of freshwater, caused by rising dissolved organic matter and iron concentrations - has been widely reported and studied during the past 30 years. Browning has affected a wide range of organisms in aquatic ecosystems, however little attention has been given to macroinvertebrates in streams and especially regarding iron concentration. In this study, I include the effects of organic matter, iron and pH on invertebrates collected from 20 sites within a stream catchment in Southern Sweden, with an aim to separate effects of the water chemistry variables on the invertebrate community. High iron concentrations and low pH negatively affected the invertebrate abundance, biomass and species richness while DOC lacked... (More)
- Browning - increased water colour of freshwater, caused by rising dissolved organic matter and iron concentrations - has been widely reported and studied during the past 30 years. Browning has affected a wide range of organisms in aquatic ecosystems, however little attention has been given to macroinvertebrates in streams and especially regarding iron concentration. In this study, I include the effects of organic matter, iron and pH on invertebrates collected from 20 sites within a stream catchment in Southern Sweden, with an aim to separate effects of the water chemistry variables on the invertebrate community. High iron concentrations and low pH negatively affected the invertebrate abundance, biomass and species richness while DOC lacked significant impact on the invertebrate community. However, DOC could have indirectly affected the invertebrates due its influence on pH. Effects of iron concentration on invertebrates may be direct since the effect could be separated from other water chemistry variables. The negative impacts of water chemistry variables linked to browning could be connected to land-use due to forestry practices. (Less)
- Popular Abstract
- Are browner waters negatively affecting invertebrates in streams?
Browning of freshwaters have been noted in during the last decades affecting thousands of waters in the northern hemisphere. Increasing dissolved organic carbon (DOC) and iron concentrations have contributed to higher water colour. Resulting in waters with colour closer to tea than tap water. Browning is known to affect aquatic life, all the way from predatory fish to green algae. Brown water limits light penetration which disrupts food chains since photosynthesising green algae at the bottom of food chains utilize light. But several pieces of the puzzle are still missing especially regarding invertebrates in streams. Are factors related to browning the most important... (More) - Are browner waters negatively affecting invertebrates in streams?
Browning of freshwaters have been noted in during the last decades affecting thousands of waters in the northern hemisphere. Increasing dissolved organic carbon (DOC) and iron concentrations have contributed to higher water colour. Resulting in waters with colour closer to tea than tap water. Browning is known to affect aquatic life, all the way from predatory fish to green algae. Brown water limits light penetration which disrupts food chains since photosynthesising green algae at the bottom of food chains utilize light. But several pieces of the puzzle are still missing especially regarding invertebrates in streams. Are factors related to browning the most important factors affecting invertebrates in brown streams?
To investigate this, I collected water samples and invertebrates on 20 sites located in southern Sweden, covering a wide range of DOC, iron, water colour and pH. Higher iron concentration resulted in higher water colour, but higher DOC caused lower pH. The community of invertebrates caught ranged from no invertebrates at all to seven species in high numbers.
Iron concentration and pH were both found to heavily influence the invertebrate community but surprisingly DOC lacked direct influence. Iron concentration affected the abundance of invertebrates most, while pH had the greatest impact on species numbers. However, since DOC lowered pH, one could argue that DOC indirectly impacted the invertebrates.
Even though iron concentration and water colour were closely connected, the effects of water colour was considered to be minor. The species of invertebrate in the catchment were mostly types feeding on organic debris rather than algae which need light to photosynthesize. Therefor iron concentration was considered to have a direct effect on the invertebrate community in this catchment. High iron concentrations are toxic to invertebrates, starting with decreased feeding and ending with death by starvation due to constipated guts.
So, are browner waters negatively affecting invertebrates in streams? Yes, but the effects on invertebrates might not be directly related to the colour of waters. In this case iron concentration was found to be of great importance but also DOC due to lowering pH.
What can be done for invertebrates in brown water streams?
To decrease the negative impacts of brown water on invertebrates in this catchment, one would need to limit the input of iron and DOC into the water of streams. This could be done by planting broad-leaf trees instead of coniferous trees, which are currently dominating and release more DOC and iron, especially near streams. The usage of clear-cutting should be avoided since removal of all trees and pre-site preparation by plowing forest soils release high levels of DOC. Finally, I would suggest restoration of ditched peatlands since they release more stored DOC and iron into streams than pristine peatlands.
Master’s Degree Project in Biology credits 30
Department of Biology, Lund University
Advisors: Emma Kritzberg and Anders Persson
Advisors Unit: Aquatic ecology (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9140006
- author
- Olsson, Gustav
- supervisor
-
- Emma Kritzberg LU
- Anders Persson LU
- organization
- course
- BIOM02 20231
- year
- 2023
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9140006
- date added to LUP
- 2023-10-13 16:16:14
- date last changed
- 2023-10-13 16:16:14
@misc{9140006,
abstract = {{Browning - increased water colour of freshwater, caused by rising dissolved organic matter and iron concentrations - has been widely reported and studied during the past 30 years. Browning has affected a wide range of organisms in aquatic ecosystems, however little attention has been given to macroinvertebrates in streams and especially regarding iron concentration. In this study, I include the effects of organic matter, iron and pH on invertebrates collected from 20 sites within a stream catchment in Southern Sweden, with an aim to separate effects of the water chemistry variables on the invertebrate community. High iron concentrations and low pH negatively affected the invertebrate abundance, biomass and species richness while DOC lacked significant impact on the invertebrate community. However, DOC could have indirectly affected the invertebrates due its influence on pH. Effects of iron concentration on invertebrates may be direct since the effect could be separated from other water chemistry variables. The negative impacts of water chemistry variables linked to browning could be connected to land-use due to forestry practices.}},
author = {{Olsson, Gustav}},
language = {{eng}},
note = {{Student Paper}},
title = {{The effects of browning related water chemistry variables (DOC, iron and pH) on macroinvertebrate communities across streams}},
year = {{2023}},
}