{"id":{"repo_id":"rgu","oai_identifier":"oai:rgu-repository.worktribe.com:2807487"},"canonical_url":"https://search.dev.ndltd.org/etd/rgu/oai:rgu-repository.worktribe.com:2807487","repository":{"repo_id":"rgu","name":"Robert Gordon University","base_url":"https://rgu-repository.worktribe.com/oaiprovider"},"display":{"title":"Biofilm development in streams draining from contrasting land use systems.","abstract":"The transport of terrestrial carbon into streams, down rivers and into the world’s oceans is an important component of the global carbon cycle. Within the carbon cycle, biotic and abiotic processes associated with biofilms in the aquatic environment may play an important role within ecosystems. This study was conducted to investigate the influence of different land use systems and their effect on colonizing and developing aquatic biofilms. On conclusion of the experiment, a model was developed to explain the growth and development of a biofilm in an aquatic environment. The model is separated into three phases, phase one is the colonisation period, phase two is the equilibrium phase controlled by external factors such as invertebrate grazing or slight increase in water flow and phase three is the decline phase caused by severe external events such as a storm producing sever water velocity. The different land use systems compared in this experiment were a young forest, a mature forest and an agricultural site. The first experiment conducted centred on the colonisation and development of aquatic biofilms on rock surfaces at a specific location within a stream in each of the three land use systems. Within the young forest site, the total material (biofilm) increased from zero to 0.29 mg cm-2 in two weeks; at four weeks the total material peaked to 1.61 mg cm-2. The composition of the total material was high in carbon biomass at 48.4 mu g cm-2. with a nitrogen biomass of 5.0 mu g cm2. However, there was a decrease in total material, carbon biomass, and nitrogen biomass in the sixth week of the experiment due to an increase in rainfall and subsequent increase in stream flow. This was so severe that all experimental baskets and rocks were swept away in the eighth week. Throughout the experiment, the carbon to nitrogen ratio of the bio film remained at an average of 10.1. Within the mature forest site the total material increased to 0.83 mg cm-2 in the first two weeks. The total material increased to 1.43 mg cm-2 in week six, however in the eighth week there was a dramatic increase in the total material to 3.94 mg cm-2. During the experiment, the composition of the total material was high in carbon biomass at 86.9 mu g cm-2 and had a nitrogen biomass of 4.37 mu g cm-2, especially in the second week. The nitrogen biomass increased steadily to 5.43 mu g cm-2 in week six, but the carbon biomass decreased to 80.7 mu g cm-2 in week six. The mature forest site was also disrupted by a high rainfall, which caused an increase in the stream flow. However, the experimental rocks were not washed away. The increased burn flow caused the rise in the total biofilm material to 3.94 mg cm-2. However, its composition changed with the carbon and nitrogen contents dropping down to 12.8 mu g cm-2 and 1.17 mu g cm-2 respectively. This suggested that the colonizing biofilm was removed from the rock and replaced by sand and silt from the re-suspended streambed sediment. Even with the drop in carbon and nitrogen biomass the average C:N ratio for the mature forest was 14.9. The biofilm at the agricultural site increased to 0.23mg cm-2 in week two, then had a steady rate of growth peaking in week four at 1.15 mg cm-2. The carbon biomass and nitrogen biomass at week four were 26.3 mu g cm-2 and 3.0 mu g cm-2. As with the young forest and mature forest the storm events also affected the agricultural site, the outcome was the same as the mature forest. The total material increased to 4.05 mg cm-2 however the carbon biomass dropped to 19.2 mg cm-2 and the nitrogen biomass was reduced to 2.37 mu g cm-2. Even though there was a drop in the carbon and nitrogen biomass the C:N ratio was 7.7. A comparison between sites showed that the mature forest had the highest carbon biomass and total material of the three sites. The agricultural site had the lowest total material, with the young forest in the middle of the two sites. The C:N ratio varied across the three sites with the mature forest having the highest C:N ratio and the agricultural site having the lowest. When the three sites are looked at in comparison to the model all three sites show phase one, however only the mature forest follows phase two, but all three sites follow phase three of the model. The experiment was repeated the following year at a different season but with the same section of the stream being used. This contrasts the effect of seasons on biofilm development. Within the first two weeks of growth in the young forest, the carbon content was high at 92.0 mu g cm-2. The carbon biomass, nitrogen biomass and total material then remained stable throughout the experiment. The average C:N ratio for the young forest was 11.9. In the mature forest site the biofilm steadily grew to a maximum in the fifth week with a value of 0.742 mg cm2 however the composition of the biofilm changed the nitrogen biomass continued to increase to 11.4 mu g cm2 in week five, like the total material. However, the carbon biomass increased dramatically to a level of 49.0 mu g cm2 in the second week, but decreased in the fifth week to 18.8 mu g cm2. By the end of the experiment the total material, carbon biomass and nitrogen biomass all decreased, even though the carbon and nitrogen biomass varied throughout the experiment. Even with the carbon and nitrogen biomass fluctuations the average C:N ratio was 12.6. The agricultural site differed from that used in the first year due to difficulties in access caused by the outbreak of foot and mouth. The amount of biofilm growth increased steadily as noted by the total material to a maximum of 0.593 mg cm-2 in the fifth week then decreased to 0.404 mg cm-2 in the eighth week. However the carbon and nitrogen biomass increased to a max of 80.1 mu g cm-2 and 10.43 mu g cm-2 in the eighth week. There was no sign that the carbon and nitrogen biomass were levelling out, even though the carbon and nitrogen biomass continued to rise the average C:N ratio was 8.3. A comparison of sites in year two showed that the mature forest has the highest carbon biomass, with the agricultural moorland having the highest % nitrogen within its biofilm. Total material collected from the three sites is similar although the slightly higher amounts at the mature forest were accompanied by the lowest nitrogen content. In the second year, all the three sites followed phase one of the model with the young forest and the agricultural site following phase two. The mature forest and agricultural site followed phase three of the model. In the second year, a further experiment looked at the difference in bio film growth at three locations 60 meters apart within each stream. In the young forest site the upstream section produced the highest amount of total material but had the lowest carbon and nitrogen biomass. The middle section had the highest carbon and nitrogen biomass. In the mature forest the down stream, position produced the highest amount of material at 1.49 mg cm-2 and had the highest amount of carbon and nitrogen biomass. The upstream section produced the least carbon and nitrogen rich biofilm. In the agricultural moorland site the down stream section produced the most total material at 5.69 mg cm-2 and the highest carbon biomass at 56.3 mu g cm-2 and nitrogen biomass at 7.3 mu g cm-2. The upstream section produced the smallest amount of carbon and nitrogen biomass at 25.9 mu g cm-2 and 3.2 mu g cm-2. The results showed that the biofilm located within the stream draining the mature forest had a high carbon biomass, with the agricultural biofilm being more restricted in its growth. Within each stream, there was variation in the amount of carbon biomass a biofilm produced depending on the location along the stream. The mature forest showed a large variation of carbon biomass within a stream section, whereas the variability was less for the young forest and the agricultural sites. Along with total material, carbon and nitrogen biomass, phospholipid fatty acids (PLFA) from the biofilms were looked at. Along with a total concentration of fatty acids, PLFA also give a microbial profile. In the first experiment, the total PLFA concentration showed that the mature forest had the highest PLFA concentration in week two, but as the experiment proceeded the PLFA concentrations of the three sites became similar. This was once again done in the second year and on the second week, the young forest had the highest PLFA concentrations. However in this year there was a wider gap in the PLFA concentrations in the sites as the experiment proceeded. In the second experiment of year two biofilms from various sections of the same stream were analysed for PLFA and therefore microbial profiles, it was discovered that initially the three locations gave differing microbial profiles but as the experiment progressed the biofilms became similar and as a consequent the PLFA profile became the same. This experiment has shown that season does have a large role in the colonisation and development of biofilms, but the effect of land use needs to be investigated further.","abstract_html":"The transport of terrestrial carbon into streams, down rivers and into the world’s oceans is an important component of the global carbon cycle. Within the carbon cycle, biotic and abiotic processes associated with biofilms in the aquatic environment may play an important role within ecosystems. This study was conducted to investigate the influence of different land use systems and their effect on colonizing and developing aquatic biofilms. On conclusion of the experiment, a model was developed to explain the growth and development of a biofilm in an aquatic environment. The model is separated into three phases, phase one is the colonisation period, phase two is the equilibrium phase controlled by external factors such as invertebrate grazing or slight increase in water flow and phase three is the decline phase caused by severe external events such as a storm producing sever water velocity. The different land use systems compared in this experiment were a young forest, a mature forest and an agricultural site. The first experiment conducted centred on the colonisation and development of aquatic biofilms on rock surfaces at a specific location within a stream in each of the three land use systems. Within the young forest site, the total material (biofilm) increased from zero to 0.29 mg cm-2 in two weeks; at four weeks the total material peaked to 1.61 mg cm-2. The composition of the total material was high in carbon biomass at 48.4 mu g cm-2. with a nitrogen biomass of 5.0 mu g cm2. However, there was a decrease in total material, carbon biomass, and nitrogen biomass in the sixth week of the experiment due to an increase in rainfall and subsequent increase in stream flow. This was so severe that all experimental baskets and rocks were swept away in the eighth week. Throughout the experiment, the carbon to nitrogen ratio of the bio film remained at an average of 10.1. Within the mature forest site the total material increased to 0.83 mg cm-2 in the first two weeks. The total material increased to 1.43 mg cm-2 in week six, however in the eighth week there was a dramatic increase in the total material to 3.94 mg cm-2. During the experiment, the composition of the total material was high in carbon biomass at 86.9 mu g cm-2 and had a nitrogen biomass of 4.37 mu g cm-2, especially in the second week. The nitrogen biomass increased steadily to 5.43 mu g cm-2 in week six, but the carbon biomass decreased to 80.7 mu g cm-2 in week six. The mature forest site was also disrupted by a high rainfall, which caused an increase in the stream flow. However, the experimental rocks were not washed away. The increased burn flow caused the rise in the total biofilm material to 3.94 mg cm-2. However, its composition changed with the carbon and nitrogen contents dropping down to 12.8 mu g cm-2 and 1.17 mu g cm-2 respectively. This suggested that the colonizing biofilm was removed from the rock and replaced by sand and silt from the re-suspended streambed sediment. Even with the drop in carbon and nitrogen biomass the average C:N ratio for the mature forest was 14.9. The biofilm at the agricultural site increased to 0.23mg cm-2 in week two, then had a steady rate of growth peaking in week four at 1.15 mg cm-2. The carbon biomass and nitrogen biomass at week four were 26.3 mu g cm-2 and 3.0 mu g cm-2. As with the young forest and mature forest the storm events also affected the agricultural site, the outcome was the same as the mature forest. The total material increased to 4.05 mg cm-2 however the carbon biomass dropped to 19.2 mg cm-2 and the nitrogen biomass was reduced to 2.37 mu g cm-2. Even though there was a drop in the carbon and nitrogen biomass the C:N ratio was 7.7. A comparison between sites showed that the mature forest had the highest carbon biomass and total material of the three sites. The agricultural site had the lowest total material, with the young forest in the middle of the two sites. The C:N ratio varied across the three sites with the mature forest having the highest C:N ratio and the agricultural site having the lowest. When the three sites are looked at in comparison to the model all three sites show phase one, however only the mature forest follows phase two, but all three sites follow phase three of the model. The experiment was repeated the following year at a different season but with the same section of the stream being used. This contrasts the effect of seasons on biofilm development. Within the first two weeks of growth in the young forest, the carbon content was high at 92.0 mu g cm-2. The carbon biomass, nitrogen biomass and total material then remained stable throughout the experiment. The average C:N ratio for the young forest was 11.9. In the mature forest site the biofilm steadily grew to a maximum in the fifth week with a value of 0.742 mg cm2 however the composition of the biofilm changed the nitrogen biomass continued to increase to 11.4 mu g cm2 in week five, like the total material. However, the carbon biomass increased dramatically to a level of 49.0 mu g cm2 in the second week, but decreased in the fifth week to 18.8 mu g cm2. By the end of the experiment the total material, carbon biomass and nitrogen biomass all decreased, even though the carbon and nitrogen biomass varied throughout the experiment. Even with the carbon and nitrogen biomass fluctuations the average C:N ratio was 12.6. The agricultural site differed from that used in the first year due to difficulties in access caused by the outbreak of foot and mouth. The amount of biofilm growth increased steadily as noted by the total material to a maximum of 0.593 mg cm-2 in the fifth week then decreased to 0.404 mg cm-2 in the eighth week. However the carbon and nitrogen biomass increased to a max of 80.1 mu g cm-2 and 10.43 mu g cm-2 in the eighth week. There was no sign that the carbon and nitrogen biomass were levelling out, even though the carbon and nitrogen biomass continued to rise the average C:N ratio was 8.3. A comparison of sites in year two showed that the mature forest has the highest carbon biomass, with the agricultural moorland having the highest % nitrogen within its biofilm. Total material collected from the three sites is similar although the slightly higher amounts at the mature forest were accompanied by the lowest nitrogen content. In the second year, all the three sites followed phase one of the model with the young forest and the agricultural site following phase two. The mature forest and agricultural site followed phase three of the model. In the second year, a further experiment looked at the difference in bio film growth at three locations 60 meters apart within each stream. In the young forest site the upstream section produced the highest amount of total material but had the lowest carbon and nitrogen biomass. The middle section had the highest carbon and nitrogen biomass. In the mature forest the down stream, position produced the highest amount of material at 1.49 mg cm-2 and had the highest amount of carbon and nitrogen biomass. The upstream section produced the least carbon and nitrogen rich biofilm. In the agricultural moorland site the down stream section produced the most total material at 5.69 mg cm-2 and the highest carbon biomass at 56.3 mu g cm-2 and nitrogen biomass at 7.3 mu g cm-2. The upstream section produced the smallest amount of carbon and nitrogen biomass at 25.9 mu g cm-2 and 3.2 mu g cm-2. The results showed that the biofilm located within the stream draining the mature forest had a high carbon biomass, with the agricultural biofilm being more restricted in its growth. Within each stream, there was variation in the amount of carbon biomass a biofilm produced depending on the location along the stream. The mature forest showed a large variation of carbon biomass within a stream section, whereas the variability was less for the young forest and the agricultural sites. Along with total material, carbon and nitrogen biomass, phospholipid fatty acids (PLFA) from the biofilms were looked at. Along with a total concentration of fatty acids, PLFA also give a microbial profile. In the first experiment, the total PLFA concentration showed that the mature forest had the highest PLFA concentration in week two, but as the experiment proceeded the PLFA concentrations of the three sites became similar. This was once again done in the second year and on the second week, the young forest had the highest PLFA concentrations. However in this year there was a wider gap in the PLFA concentrations in the sites as the experiment proceeded. In the second experiment of year two biofilms from various sections of the same stream were analysed for PLFA and therefore microbial profiles, it was discovered that initially the three locations gave differing microbial profiles but as the experiment progressed the biofilms became similar and as a consequent the PLFA profile became the same. This experiment has shown that season does have a large role in the colonisation and development of biofilms, but the effect of land use needs to be investigated further.","abstract_has_math":false,"creators":["McWhinnie, Margaret Jane"],"institution":"Robert Gordon University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["S. Chapman and T. Edwards"],"committee_chairs":[],"committee_members":[],"year":2003,"date_issued":"2003","date_published":"2003","updated_at":"2026-07-24T04:10:12Z","subjects":["Aquatic biofilms","Land-use effects","Carbon and nitrogen biomass","Stream flow disturbance","Phospholipid fatty acids (PLFA)","Seasonal variation"],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["oai:rgu-repository.worktribe.com:2807487","https://doi.org/10.48526/rgu-wt-2807487"],"render_values":[{"text":"oai:rgu-repository.worktribe.com:2807487","href":null,"code":true},{"text":"https://doi.org/10.48526/rgu-wt-2807487","href":"https://doi.org/10.48526/rgu-wt-2807487","code":true}]}]},"links":{"outbound_url":"https://rgu-repository.worktribe.com/2807487/1/MCWHINNIE%202003%20Biofilm%20development%20in%20streams","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["S. 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Within the carbon cycle, biotic and abiotic processes associated with biofilms in the aquatic environment may play an important role within ecosystems. This study was conducted to investigate the influence of different land use systems and their effect on colonizing and developing aquatic biofilms. On conclusion of the experiment, a model was developed to explain the growth and development of a biofilm in an aquatic environment. The model is separated into three phases, phase one is the colonisation period, phase two is the equilibrium phase controlled by external factors such as invertebrate grazing or slight increase in water flow and phase three is the decline phase caused by severe external events such as a storm producing sever water velocity. The different land use systems compared in this experiment were a young forest, a mature forest and an agricultural site. The first experiment conducted centred on the colonisation and development of aquatic biofilms on rock surfaces at a specific location within a stream in each of the three land use systems. Within the young forest site, the total material (biofilm) increased from zero to 0.29 mg cm-2 in two weeks; at four weeks the total material peaked to 1.61 mg cm-2. The composition of the total material was high in carbon biomass at 48.4 mu g cm-2. with a nitrogen biomass of 5.0 mu g cm2. However, there was a decrease in total material, carbon biomass, and nitrogen biomass in the sixth week of the experiment due to an increase in rainfall and subsequent increase in stream flow. This was so severe that all experimental baskets and rocks were swept away in the eighth week. Throughout the experiment, the carbon to nitrogen ratio of the bio film remained at an average of 10.1. Within the mature forest site the total material increased to 0.83 mg cm-2 in the first two weeks. The total material increased to 1.43 mg cm-2 in week six, however in the eighth week there was a dramatic increase in the total material to 3.94 mg cm-2. During the experiment, the composition of the total material was high in carbon biomass at 86.9 mu g cm-2 and had a nitrogen biomass of 4.37 mu g cm-2, especially in the second week. The nitrogen biomass increased steadily to 5.43 mu g cm-2 in week six, but the carbon biomass decreased to 80.7 mu g cm-2 in week six. The mature forest site was also disrupted by a high rainfall, which caused an increase in the stream flow. However, the experimental rocks were not washed away. The increased burn flow caused the rise in the total biofilm material to 3.94 mg cm-2. However, its composition changed with the carbon and nitrogen contents dropping down to 12.8 mu g cm-2 and 1.17 mu g cm-2 respectively. This suggested that the colonizing biofilm was removed from the rock and replaced by sand and silt from the re-suspended streambed sediment. Even with the drop in carbon and nitrogen biomass the average C:N ratio for the mature forest was 14.9. The biofilm at the agricultural site increased to 0.23mg cm-2 in week two, then had a steady rate of growth peaking in week four at 1.15 mg cm-2. The carbon biomass and nitrogen biomass at week four were 26.3 mu g cm-2 and 3.0 mu g cm-2. As with the young forest and mature forest the storm events also affected the agricultural site, the outcome was the same as the mature forest. The total material increased to 4.05 mg cm-2 however the carbon biomass dropped to 19.2 mg cm-2 and the nitrogen biomass was reduced to 2.37 mu g cm-2. Even though there was a drop in the carbon and nitrogen biomass the C:N ratio was 7.7. A comparison between sites showed that the mature forest had the highest carbon biomass and total material of the three sites. The agricultural site had the lowest total material, with the young forest in the middle of the two sites. The C:N ratio varied across the three sites with the mature forest having the highest C:N ratio and the agricultural site having the lowest. When the three sites are looked at in comparison to the model all three sites show phase one, however only the mature forest follows phase two, but all three sites follow phase three of the model. The experiment was repeated the following year at a different season but with the same section of the stream being used. This contrasts the effect of seasons on biofilm development. Within the first two weeks of growth in the young forest, the carbon content was high at 92.0 mu g cm-2. The carbon biomass, nitrogen biomass and total material then remained stable throughout the experiment. The average C:N ratio for the young forest was 11.9. In the mature forest site the biofilm steadily grew to a maximum in the fifth week with a value of 0.742 mg cm2 however the composition of the biofilm changed the nitrogen biomass continued to increase to 11.4 mu g cm2 in week five, like the total material. However, the carbon biomass increased dramatically to a level of 49.0 mu g cm2 in the second week, but decreased in the fifth week to 18.8 mu g cm2. By the end of the experiment the total material, carbon biomass and nitrogen biomass all decreased, even though the carbon and nitrogen biomass varied throughout the experiment. Even with the carbon and nitrogen biomass fluctuations the average C:N ratio was 12.6. The agricultural site differed from that used in the first year due to difficulties in access caused by the outbreak of foot and mouth. The amount of biofilm growth increased steadily as noted by the total material to a maximum of 0.593 mg cm-2 in the fifth week then decreased to 0.404 mg cm-2 in the eighth week. However the carbon and nitrogen biomass increased to a max of 80.1 mu g cm-2 and 10.43 mu g cm-2 in the eighth week. There was no sign that the carbon and nitrogen biomass were levelling out, even though the carbon and nitrogen biomass continued to rise the average C:N ratio was 8.3. A comparison of sites in year two showed that the mature forest has the highest carbon biomass, with the agricultural moorland having the highest % nitrogen within its biofilm. Total material collected from the three sites is similar although the slightly higher amounts at the mature forest were accompanied by the lowest nitrogen content. In the second year, all the three sites followed phase one of the model with the young forest and the agricultural site following phase two. The mature forest and agricultural site followed phase three of the model. In the second year, a further experiment looked at the difference in bio film growth at three locations 60 meters apart within each stream. In the young forest site the upstream section produced the highest amount of total material but had the lowest carbon and nitrogen biomass. The middle section had the highest carbon and nitrogen biomass. In the mature forest the down stream, position produced the highest amount of material at 1.49 mg cm-2 and had the highest amount of carbon and nitrogen biomass. The upstream section produced the least carbon and nitrogen rich biofilm. In the agricultural moorland site the down stream section produced the most total material at 5.69 mg cm-2 and the highest carbon biomass at 56.3 mu g cm-2 and nitrogen biomass at 7.3 mu g cm-2. The upstream section produced the smallest amount of carbon and nitrogen biomass at 25.9 mu g cm-2 and 3.2 mu g cm-2. The results showed that the biofilm located within the stream draining the mature forest had a high carbon biomass, with the agricultural biofilm being more restricted in its growth. Within each stream, there was variation in the amount of carbon biomass a biofilm produced depending on the location along the stream. The mature forest showed a large variation of carbon biomass within a stream section, whereas the variability was less for the young forest and the agricultural sites. Along with total material, carbon and nitrogen biomass, phospholipid fatty acids (PLFA) from the biofilms were looked at. Along with a total concentration of fatty acids, PLFA also give a microbial profile. In the first experiment, the total PLFA concentration showed that the mature forest had the highest PLFA concentration in week two, but as the experiment proceeded the PLFA concentrations of the three sites became similar. This was once again done in the second year and on the second week, the young forest had the highest PLFA concentrations. However in this year there was a wider gap in the PLFA concentrations in the sites as the experiment proceeded. In the second experiment of year two biofilms from various sections of the same stream were analysed for PLFA and therefore microbial profiles, it was discovered that initially the three locations gave differing microbial profiles but as the experiment progressed the biofilms became similar and as a consequent the PLFA profile became the same. This experiment has shown that season does have a large role in the colonisation and development of biofilms, but the effect of land use needs to be investigated further."]},{"key":"dc:title","label":"Title","values":["Biofilm development in streams draining from contrasting land use systems."]}]}],"canonical_facts":{"dc:contributor.advisor":["S. Chapman and T. Edwards"],"dc:contributor.sponsor":["RGU Internal Funding","Macaulay Development Trust"],"dc:creator":["McWhinnie, Margaret Jane"],"dc:date":["2003-12-31"],"dc:date.issued":["2003"],"dc:description.abstract":["The transport of terrestrial carbon into streams, down rivers and into the world’s oceans is an important component of the global carbon cycle. Within the carbon cycle, biotic and abiotic processes associated with biofilms in the aquatic environment may play an important role within ecosystems. This study was conducted to investigate the influence of different land use systems and their effect on colonizing and developing aquatic biofilms. On conclusion of the experiment, a model was developed to explain the growth and development of a biofilm in an aquatic environment. The model is separated into three phases, phase one is the colonisation period, phase two is the equilibrium phase controlled by external factors such as invertebrate grazing or slight increase in water flow and phase three is the decline phase caused by severe external events such as a storm producing sever water velocity. The different land use systems compared in this experiment were a young forest, a mature forest and an agricultural site. The first experiment conducted centred on the colonisation and development of aquatic biofilms on rock surfaces at a specific location within a stream in each of the three land use systems. Within the young forest site, the total material (biofilm) increased from zero to 0.29 mg cm-2 in two weeks; at four weeks the total material peaked to 1.61 mg cm-2. The composition of the total material was high in carbon biomass at 48.4 mu g cm-2. with a nitrogen biomass of 5.0 mu g cm2. However, there was a decrease in total material, carbon biomass, and nitrogen biomass in the sixth week of the experiment due to an increase in rainfall and subsequent increase in stream flow. This was so severe that all experimental baskets and rocks were swept away in the eighth week. Throughout the experiment, the carbon to nitrogen ratio of the bio film remained at an average of 10.1. Within the mature forest site the total material increased to 0.83 mg cm-2 in the first two weeks. The total material increased to 1.43 mg cm-2 in week six, however in the eighth week there was a dramatic increase in the total material to 3.94 mg cm-2. During the experiment, the composition of the total material was high in carbon biomass at 86.9 mu g cm-2 and had a nitrogen biomass of 4.37 mu g cm-2, especially in the second week. The nitrogen biomass increased steadily to 5.43 mu g cm-2 in week six, but the carbon biomass decreased to 80.7 mu g cm-2 in week six. The mature forest site was also disrupted by a high rainfall, which caused an increase in the stream flow. However, the experimental rocks were not washed away. The increased burn flow caused the rise in the total biofilm material to 3.94 mg cm-2. However, its composition changed with the carbon and nitrogen contents dropping down to 12.8 mu g cm-2 and 1.17 mu g cm-2 respectively. This suggested that the colonizing biofilm was removed from the rock and replaced by sand and silt from the re-suspended streambed sediment. Even with the drop in carbon and nitrogen biomass the average C:N ratio for the mature forest was 14.9. The biofilm at the agricultural site increased to 0.23mg cm-2 in week two, then had a steady rate of growth peaking in week four at 1.15 mg cm-2. The carbon biomass and nitrogen biomass at week four were 26.3 mu g cm-2 and 3.0 mu g cm-2. As with the young forest and mature forest the storm events also affected the agricultural site, the outcome was the same as the mature forest. The total material increased to 4.05 mg cm-2 however the carbon biomass dropped to 19.2 mg cm-2 and the nitrogen biomass was reduced to 2.37 mu g cm-2. Even though there was a drop in the carbon and nitrogen biomass the C:N ratio was 7.7. A comparison between sites showed that the mature forest had the highest carbon biomass and total material of the three sites. The agricultural site had the lowest total material, with the young forest in the middle of the two sites. The C:N ratio varied across the three sites with the mature forest having the highest C:N ratio and the agricultural site having the lowest. When the three sites are looked at in comparison to the model all three sites show phase one, however only the mature forest follows phase two, but all three sites follow phase three of the model. The experiment was repeated the following year at a different season but with the same section of the stream being used. This contrasts the effect of seasons on biofilm development. Within the first two weeks of growth in the young forest, the carbon content was high at 92.0 mu g cm-2. The carbon biomass, nitrogen biomass and total material then remained stable throughout the experiment. The average C:N ratio for the young forest was 11.9. In the mature forest site the biofilm steadily grew to a maximum in the fifth week with a value of 0.742 mg cm2 however the composition of the biofilm changed the nitrogen biomass continued to increase to 11.4 mu g cm2 in week five, like the total material. However, the carbon biomass increased dramatically to a level of 49.0 mu g cm2 in the second week, but decreased in the fifth week to 18.8 mu g cm2. By the end of the experiment the total material, carbon biomass and nitrogen biomass all decreased, even though the carbon and nitrogen biomass varied throughout the experiment. Even with the carbon and nitrogen biomass fluctuations the average C:N ratio was 12.6. The agricultural site differed from that used in the first year due to difficulties in access caused by the outbreak of foot and mouth. The amount of biofilm growth increased steadily as noted by the total material to a maximum of 0.593 mg cm-2 in the fifth week then decreased to 0.404 mg cm-2 in the eighth week. However the carbon and nitrogen biomass increased to a max of 80.1 mu g cm-2 and 10.43 mu g cm-2 in the eighth week. There was no sign that the carbon and nitrogen biomass were levelling out, even though the carbon and nitrogen biomass continued to rise the average C:N ratio was 8.3. A comparison of sites in year two showed that the mature forest has the highest carbon biomass, with the agricultural moorland having the highest % nitrogen within its biofilm. Total material collected from the three sites is similar although the slightly higher amounts at the mature forest were accompanied by the lowest nitrogen content. In the second year, all the three sites followed phase one of the model with the young forest and the agricultural site following phase two. The mature forest and agricultural site followed phase three of the model. In the second year, a further experiment looked at the difference in bio film growth at three locations 60 meters apart within each stream. In the young forest site the upstream section produced the highest amount of total material but had the lowest carbon and nitrogen biomass. The middle section had the highest carbon and nitrogen biomass. In the mature forest the down stream, position produced the highest amount of material at 1.49 mg cm-2 and had the highest amount of carbon and nitrogen biomass. The upstream section produced the least carbon and nitrogen rich biofilm. In the agricultural moorland site the down stream section produced the most total material at 5.69 mg cm-2 and the highest carbon biomass at 56.3 mu g cm-2 and nitrogen biomass at 7.3 mu g cm-2. The upstream section produced the smallest amount of carbon and nitrogen biomass at 25.9 mu g cm-2 and 3.2 mu g cm-2. The results showed that the biofilm located within the stream draining the mature forest had a high carbon biomass, with the agricultural biofilm being more restricted in its growth. Within each stream, there was variation in the amount of carbon biomass a biofilm produced depending on the location along the stream. The mature forest showed a large variation of carbon biomass within a stream section, whereas the variability was less for the young forest and the agricultural sites. Along with total material, carbon and nitrogen biomass, phospholipid fatty acids (PLFA) from the biofilms were looked at. Along with a total concentration of fatty acids, PLFA also give a microbial profile. In the first experiment, the total PLFA concentration showed that the mature forest had the highest PLFA concentration in week two, but as the experiment proceeded the PLFA concentrations of the three sites became similar. This was once again done in the second year and on the second week, the young forest had the highest PLFA concentrations. However in this year there was a wider gap in the PLFA concentrations in the sites as the experiment proceeded. In the second experiment of year two biofilms from various sections of the same stream were analysed for PLFA and therefore microbial profiles, it was discovered that initially the three locations gave differing microbial profiles but as the experiment progressed the biofilms became similar and as a consequent the PLFA profile became the same. This experiment has shown that season does have a large role in the colonisation and development of biofilms, but the effect of land use needs to be investigated further."],"dc:identifier":["oai:rgu-repository.worktribe.com:2807487","https://doi.org/10.48526/rgu-wt-2807487"],"dc:identifier.uri":["https://rgu-repository.worktribe.com/2807487/1/MCWHINNIE%202003%20Biofilm%20development%20in%20streams"],"dc:language":["en"],"dc:publisher.institution":["Robert Gordon University"],"dc:relation.isreferencedby":["https://rgu-repository.worktribe.com/output/2807487"],"dc:subject":["Aquatic biofilms","Land-use effects","Carbon and nitrogen biomass","Stream flow disturbance","Phospholipid fatty acids (PLFA)","Seasonal variation"],"dc:title":["Biofilm development in streams draining from contrasting land use systems."],"dc:type":["Thesis"]},"updated_at":"2026-07-24T04:10:12Z"}