Course:EOSC311/2021/Geological Interactions with Freshwater Fish Populations in the Pacific Northwest

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Aquatic geology is in constant flux. Many forces can constantly change the makeup and structure of our freshwater streams and basins. These changes affect the fish species which occupy them; potentially determining what species can survive, how they grow, what food sources are available to them, and even how they may reproduce.

Geology and my Major

Although my current degree is in Human Kinetics, I plan to use this degree as a prerequisite for a masters in science of freshwater ecology. As well as relating to my masters, this document will relate to my undergraduate degree through descriptions of what human impact can have on freshwater species through a geological lens. aside from potential human impacts, I will also explore natural cause and effect relationships between geology and fish populations in the Canadian Pacific Northwest.

Factors (determinants for freshwater species)

Substrate Variability

Minerals and metals can either be dissolved or suspended within freshwater bodies. Depending on how this happens can affect fish species in many ways. Dissolved metals within water can easily be absorbed through gills, as they provide a negative blood ph balance which will bind to dissolved metals such as lead, copper, mercury, and cadmium. [1] Metals in the waterways are obviously influenced by the geological occurrence of these near any body of water. For example the Omineca region of BC has a amount of copper in the region, which in turn shows that its dissolved copper concentration in local freshwater is also high.[2] The effects of metal concentrations in water ways mostly affect mortality rate and spawning of freshwater salmonids. Typically any area with dissolved concentrations higher than recommended limits could exponentially increase mortality rate of fish species. Spawning would also be affected as high concentrations of heavy metals can harm the ability to produce viable eggs as well as cause lethargy. [3]

T1. Dissolved heavy metals within periods of high and low exchange rate, and their recommended concentrations for rainbow trout populations. (Davidson, J. 2009)[3]

Concentrations of metals and other substrates would also vary depending on the exchange of the water. During high exchange the water level in a stream is higher and dilutes the concentration of substrates as well as cycles them faster down stream. Additionally when the level is higher initially, erosion occurs at a faster rate, causing higher turbidity and increased levels of non dissolved substrates such as silica, clay, and silt. During low exchange the water level sits lower which will increase concentrations of dissolved substrates in the water. [3] One study based on the watersheds of east coast salmonids showed that during high exchange the % of recycled flow was 23.5% higher. However during low exchange the same study found that the density of feed in the water was higher (1.3 vs 0.13 kg feed/m3 makeup water/ day). [4] Based on this an inference could be made that fresh water fish species require both periods of high and low exchange to thrive, too much of one or the other could cause and increase in mortality due to metal toxicity or starvation. [5]

Structure

If there's one commonality between all fresh water fish it's that they all like structure. For fish species, structure can mean protection from predators, correct changes in currents, sources of food, and much more. [6][7]

Lakes

Lakes can often be a trickier source of structure for fish due to them being larger, deeper bodies of water with less current and not as much concentrated debris as what may be found near a river. However this does not mean it doesn't exist. Larger lakes often have furrows along the bottom which can extend up to 150 meters long and 2 meters wide. [6] These furrows are most likely caused due to periodic failure of steep slopes found under the surface of the lake and near the shore line. They point to distribution of lacustrine sediment due to geological processes instead of due to surface waves or current. Once these develop in lakes they form layers of organic matter layer on top of a layer of grey-brown sediment which had little residual strength all on top of a larger layer of clay and silt. This composition is common of most lakes in the pacific northwest. [6][8] The sediment layer often contains limestone, granite, and aragonite, however it also reflects the local composition of rocks and minerals in the area. These furrows are home to many species as they provide great hiding places for bottom feeding fish such as, burbot, lake trout, whitefish, and many other species.[9][10] They also provide optimal holding areas for food for these fish, ranging from smaller bottom feeders such as sculpin to invertebrates like crayfish and freshwater insect nymphs. [10] Slow lake currents will move these food sources into these furrows which in turn causes congregation of fish. The organic top layer usually consists of decaying plant and animal life which sustains new aquatic plant growth and insect/invertebrate hatching. [6][8]

P1. Furrows developed by geological processes in Lake Okanagan. [6]

The decaying organic top layer creates a nutrient dense environment which supports a variety of species. [10] This layer is not only influenced by decaying living things but also nutrient rich sediment which is washed into lakes by attributed rivers. Eroded sediment from rivers tends to have a very fine grain size by the time it reaches a lake. Fine sediment is extremely helpful for freshwater plant species as it is easy for the root structure to penetrate and allows for nutrient absorption from every angle. [10] Facilitating good growth of freshwater vegetation is incredibly important in lakes as once again they provide structure. They allow for the same sort of feeding as the furrow would facilitate as well as protection from both airborne and swimming predators.

Streams

Freshwater streams provide home to just as many fish populations as lakes, although have different geological processes governing them. Obviously streams are a major part of the water cycle as they typically move and cycle runoff and snow/glacial melt. [11]The headwaters provide a huge influence on how they may flow which can in turn be good or bad for the fish. Glacial headwaters tend to wash more silt into a waterway which keep the water more opaque and much colder. [11] Headwaters seeming from non-glacial sources tend to be much more clear, warm and support more plant/algae growth.

Glacial Melt and Additional Precipitation (periods of high exchange)

Glacial melt is not something new, in fact it has influenced the terraforming of the world we know throughout the last millennia. [11] During accelerated times of melt (Spring/Summer) stream levels in the pacific northwest rise. During this period water is significantly cooler, and has a higher turbidity. The coolness of the water will drive salmonids closer to the surface to feed, and other species such as pike or bass proceed deeper or into shallow water.[12] During this period of high exchange there is a higher dissolved oxygen level in the water which helps to energize all the fish for spring feeding and develops aquatic vegetation. [12] High exchange also washes more organic matter into the flow along with eroded sediment. This sediment causes a much higher turbidity which fish have a harder time navigating, thus they feed on foods which will cause a shadow or disturbance on the water. [12][10] This can include terrestrial insects or even small rodents in addition to other small fish which all cause movement detectable to larger predators.[13] These larger meals are more infrequent than the hatches of insects they will feed on in the later periods of low exchange, however they do provide enough sustenance for fish to prepare for their spawns.[9][13]

Another important process of high exchange is changing composition of the river beds. More water moving through can completely change an underwater ecosystem. Firstly high flow will wash away exhausted nutrients (insect casings, carcasses, nutrient poor sediment) and repopulate it with fresh nutrient dense sediments from terrestrial sources. Additionally it may move larger stones and debris around. Salmonids like Bull trout and Cutthroat trout require riverbeds with rocky bottoms as they blend the best from predators among them. [7] These rocky beds are also home to many aquatic hatching insects as they lay their eggs under them in the fall and they hatch in the spring or summer when they will become an ideal food source. [7] Other debris like deadfall and eroded roots make great hiding places for feeding fish and spawning insects; it's more typical to find rainbow trout as well as warm water species among this type of structure.

Atypical periods of high exchange due to extreme precipitation can also have quite an impact on freshwater ecosystems. Not only will they wash away any sort of structure in a system, they can change the entire geological makeup of the stream. Fish need to be in the right place during these events as they can be washed away and injured. [14]Rapidly increased sediment levels can lower the structural integrity of banks, often causing large pieces of debris to move down stream, these may stir up beds of eggs or food sources leaving fish starving. This rapid erosion and high water levels can also change the entire stream, redirecting it through new areas and drying the beds of others. Overall this process is healthy for the ecosystem in the longterm as it refreshes nutrients through a whole system, however in the short term is can damage fish populations via they're food chain, and reproductive requirements.[11][15][14]

The Water Cycle and Fish Spawning

All fish species spawn at different times, even different from area to area, however it is fairly consistent to see salmonids and other species spawning during transition periods of high and low exchange.[9][10] Contrary to salt water species which will run into freshwater streams during the late summer and fall then die at the end of their spawn; fresh water salmonids typically do not die after their spawn and can reproduce in a variety of places depending on species. Fish, regardless of species will bulk up prior to their spawn, lake fish can do this continuously whereas river fish must be more targeted in their feeding, as patterns are not consistent.[10]

Typically fish living in lakes will spawn as soon as the ice comes off or the water temperature increases to about 10°C. Cold water salmonids living in lake will spawn in upstream tributaries towards the original headwater. Warm water and cool water species such as Northern Pike, Bass, Pike Minnow, or Burbot will spawn within their home lakes, sometimes close to shore or deep within furrows. [9] When water levels are higher these fish can move into shallower water due to higher turbidity, which will allow them to lay they're eggs more discretely. [7]

River based cold water fish species will bulk up during periods of high exchange and spawn close to their streams headwaters during transitional periods of high and low exchange. This period is ideal as it provides enough turbidity to be protected from airborne predators during a run. It also provides a warming environment for the eggs as they develop, the warming water temperatures will incubate the eggs through the summer months as they hatch in the late summer and fall.[16] Warm and cool water species tend to do the opposite, spawning in areas with snow moving current and lots of debris to use as shelter, even sometimes moving into lakes.[16]

Warm Weather and Periods of Low Exchange

As the weather warms and spring runoff slows, streams start to stabilize in terms of turbidity, temperature, and sediment movement. The one exception is glacial fed streams will still stabilize although remain quite cold and still have a moderate turbidity due to glacial silt melting in through warmer months.[11] Post runoff streams will see water levels drop, in some cases up to 2 meters depending on precipitation. [10] With this, sediment has moved towards the tail-waters and added to the contributing delta, thus reducing turbidity in the water. Added clarity in the water makes fish species more easily targeted by airborne predators, however this is not always their greatest threat. Depending on the makeup of the sediment bed, particularly its colour, water temperatures in streams will see they're fastest changes of the year; increasing rapidly due to solar radiation. [1][17]As the ground thaws we also see geothermal heat sources increase river temperatures, although this change is more stable than that of solar. Rapid rise in temperature will drive salmonids into deeper pools primarily, although they do venture away to feed. [13]Warm and cool water species will do the opposite, moving into shallower riffles and eddies which are dense with hatching insects and smaller fish. The warmer water temperatures will put cold water species under stress which can make them extremely vulnerable to human impact.

Human Impacts on Freshwater Geology

Humans have acted in many ways through history to control the flow of fresh water. From dams and reservoirs to bridges, roads, and buildings. Man made changes to the geology of a freshwater ecosystem have vast repercussions on fish populations.

Dams and Reservoirs

For freshwater fish dams can prove to be a major obstacle in their lifecycle. Firstly they can rapidly change flows from high to low exchange and vice versa. If this is not regulated carefully it may stress fish. [18]Through careful study of water cycling on these ecosystems, dam operators can choose the right times and create a schedule which will cause minimal harm to the fish. The most major concern is when new dams are created or old dams are removed, there will be a crucial adjustment period which must be acknowledged to keep the fish safe.[18] Dams can also provide a source of food for fish living below them. When they open they may move aquatic insects and other food sources into the river, enriching the nutrients and dissolved oxygen in the water below. [15]Although dams can prove to be a major obstacle for spawning salmon which return to their home water every year, they typically don't pose as much of an issue to fresh water species. Fresh water salmonids do return to their headwaters, however if an obstacle impedes that they can still spawn in a different area.[16][18] Occasionally they will end up in another species spawning ground which can cause hybrids such as "cutbows".[19] Modern dams include specially designed fish ladders so this becomes less of an issue.

Reservoirs come as a counter part to dams, being the basin of water which is being controlled. Some of these reservoirs may be man made and uninhabited but this is more rare in the west. Usually the dams regulate an existing body of water [1] which plays host to an already existing ecosystem. Initially the creation of a reservoir can cause a shock to a flowing ecosystem, slowing the cycling of sediment and organic matter. [7][18]Usually once this shock is overcome and the system reaches an equilibrium there's an increase in aquatic life. Due to a more stable current aquatic plant life can grow larger sometime reaching the surface. This must be watched very closely as an overgrowth can deoxygenate the water and kill the fish along with the rest of the ecosystem.[20] When regulated correctly fish food sources can drastically increase, allowing for the fish to feast more similarly to lake born species.

P2. Phots of Howe Sound and Squamish River in Relation to Britannia Mine [21]
Non-aquatic Man Made Structures

Other man made structures can have an effect on freshwater ecosystems too. Structures like bridges can stir up a bed when initially constructed but actually provide good protection for fish from predators. Water treatment facilities which empty into streams can increase biodiversity by releasing water rich in nitrogen, oxygen, potassium, and phosphorus; causing increased plant growth and consistent food sources for fish.[20] [2] If these chemical released are monitored and regulated properly they will support a rich environment for many fish populations, but if done incorrectly they can decimate the ecosystem. [18][20]For example mining can release toxic chemicals into watersheds, Britannia Mine in Squamish, BC is a prime example.[3] During its operation byproduct metal sulphides were washed into the Squamish River and Howe Sound, causing entire populations of fish to die and killing food sources for others. The official cause of this is acid rock drainage (ARD) which is caused when the metal sulphides react with oxygen to form sulphuric acid which decreased water pH to a disastrous level. [21]

Conclusion of Geological Impacts on Freshwater Fish Populations

Overall freshwater geology has a large impact on freshwater fish of all kinds. It directly impacts the composition of the water they live in as well as the structure of their homes. They are resilient to some changes and drastically affected by others. Ecosystems exist in a balance where geological impacts are only one small portion of what it takes to create a flourishing population. For fish, geology creates and takes away their homes, brings them food, and allows them places to procreate. They existed strongly on their own and prior to human involvement they had no needs for geological interventions. Unfortunately due to poor understandings of these delicate ecosystems man made changes to the geology of streams and lakes can severely impact their health. It takes intense monitoring and research to build these structures safely with minimal impact to the environment. A job which geologists and ecologists can work together to create better understandings and less impact. When building structures we must always be mindful of the environmental impacts and consider the risks to fresh water fish populations. Fortunately this research is being performed and progress has been made towards the safety and protection of the freshwater ecosystem.

References

1. Nowak, R., Bauer, B. O., & Siddiqua, S. (2020). The nature and origin of furrows in lake-bed sediments; okanagan lake, british columbia, canada. Canadian Journal of Earth Sciences, 57(8), 971-980. https://doi.org/10.1139/cjes-2019-0054

2. Schwartz, M. L., Curtis, P. J., & Playle, R. C. (2004). Influence of natural organic matter source on acute copper, lead, and cadmium toxicity to rainbow trout (oncorhynchus mykiss). Environmental Toxicology and Chemistry, 23(12), 2889-2899. https://doi.org/10.1897/03-561.1

3. Ishiyama, N., Miura, K., Inoue, T., Sueyoshi, M., & Nakamura, F. (2020). Geology-dependent impacts of forest conversion on stream fish diversity. Conservation Biology, https://doi.org/10.1111/cobi.13655

4. Neff, M. R., & Jackson, D. A. (2012). Geology as a structuring mechanism of stream fish communities. Transactions of the American Fisheries Society (1900), 141(4), 962-974. https://doi.org/10.1080/00028487.2012.676591

5. Sharpe, W. E., Leibfried, V. G., Kimmel, W. G., & DeWalle, D. R. (1987). the relationship of water quality and fish occurrence to soils and geology in an area of high hydrogen and sulfate ion deposition. Journal of the American Water Resources Association, 23(1), 37-46. https://doi.org/10.1111/j.1752-1688.1987.tb00782.x

6. B.C. Ministry of Environment and Climate Change Strategy 2019. Copper Water Quality Guideline for the Protection of Freshwater Aquatic Life-Technical Report. Water Quality Guideline Series, WQG-03-1. Prov. B.C., Victoria B.C.

7. Davidson, J., Good, C., Welsh, C., Brazil, B., & Summerfelt, S. (2009). Heavy metal and waste metabolite accumulation and their potential effect on rainbow trout performance in a replicated water reuse system operated at low or high system flushing rates. Aquacultural Engineering, 41(2), 136–145. https://doi.org/10.1016/j.aquaeng.2009.04.001

8. Good, C., Davidson, J., Welsh, C., Brazil, B., Snekvik, K., & Summerfelt, S. (2009). The impact of water exchange rate on the health and performance of rainbow trout Oncorhynchus mykiss in water recirculation aquaculture systems. Aquaculture, 294(1-2), 80–85. https://doi.org/10.1016/j.aquaculture.2009.05.014

9. Good, C., Davidson, J., Early, R., Webber, G., & Summerfelt, S. (2013, September). Effects of water exchange rate and biofiltration on circulating hormones in water recirculation aquaculture systems containing sexually maturing Atlantic salmon. https://makeway.org. https://makeway.org/wp-content/uploads/2015/03/D-1-3ChrisGooD-.pdf.

  1. ↑ 1.0 1.1 Cite error: Invalid <ref> tag; no text was provided for refs named :0
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :1
  3. ↑ 3.0 3.1 3.2 Cite error: Invalid <ref> tag; no text was provided for refs named :2
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :3
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named :4
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Cite error: Invalid <ref> tag; no text was provided for refs named :5
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Cite error: Invalid <ref> tag; no text was provided for refs named :6
  8. ↑ 8.0 8.1 Cite error: Invalid <ref> tag; no text was provided for refs named :7
  9. ↑ 9.0 9.1 9.2 9.3 "Freshwater fish".
  10. ↑ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 Baird, Donald (2010). "Biodiversity in Canadian lakes and rivers". Canadian Biodiversity: Ecosystem Status and Trends – via Canadian Councils of Resource Ministers.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 "Ice, Snow, and Glaciers and the Water Cycle". USGS.
  12. ↑ 12.0 12.1 12.2 "HOW WATER TEMPERATURE AND OXYGEN AFFECT FISHING". Mepps.com.
  13. ↑ 13.0 13.1 13.2 F. LIEM, KAREL. "Aquatic Versus Terrestrial Feeding Modes: Possible Impacts on the Trophic Ecology of Vertebrates". Museum of Comparative Zoology – via Harvard University, Cambridge.
  14. ↑ 14.0 14.1 D. Rijnsdorp, Adriaan. "Resolving the effect of climate change on fish populations". ICES Journal of Marine Science.
  15. ↑ 15.0 15.1 Cite error: Invalid <ref> tag; no text was provided for refs named :14
  16. ↑ 16.0 16.1 16.2 "freshwater fish spawning times factors". www.takemefishing.org.
  17. ↑ "Soil Erosion and Sediment Pollution". www.waterontheweb.org.
  18. ↑ 18.0 18.1 18.2 18.3 18.4 Maheu, Audrey (16 August 2016). "A regional analysis of the impact of dams on water temperature in medium-size rivers in eastern Canada". Canadian Journal of Fisheries and Aquatic Sciences.
  19. ↑ "Trout of North America the Complete Guide". fishingbooker.com.
  20. ↑ 20.0 20.1 20.2 Patel, Vaidehi. "Impacts of Calgary's Municipal Wastewater Treatment Plant Effluents on Reproduction of Fish in the Bow River" (PDF). University of Calgary, Calgary, AB.
  21. ↑ 21.0 21.1 "Environment". www.britanniaminemuseum.ca.
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