Climate Change and The Fishes, by Don Orth

F. Sherwood Rowland was an atmospheric scientist who studied inert gases, namely chlorofluorocarbons (CFCs), widely used as refrigerants and aerosol propellants. In a 1974 paper in Nature, he first recognized the threat that CFCs posed to the Earth’s ozone layer.  As the story goes, one evening he remarked to his wife, Joan, that the research “is going very well, but it may mean the end of the world.”  His research and associated “fear and doom” led to global environmental action to eliminate CFCs, which were eventually banned. Rowland’s research saved the planet; it did not mean the end of the world.   

Today, most atmospheric scientists accept the reality of global climate change and each year new records are set (Feltman 2017).  Yet, many atmospheric scientists who study global climate are criticized for framing the climate change with language that connotes fear and doom. Researchers Michael Mann and Lee Kump, in Dire Predictions: Understanding Climate Change, present the evidence to support the contention that climate change is real, caused by human activities, and is already a threat. There is no longer any excuse for delaying a shift away from fossil fuel energy.  The research is based on basic principles of physics and chemistry that allow us to predict that the Earth will warm as concentrations of greenhouse gases increase.  Of course, Mann and Kump have been criticized for creating alarmism in the climate sciences. 

 

Number of years per decade that had above-average temperatures—and how many of those years rose a half, or even a whole, degree above the norm (Feltman 2017). 

We do not know how fishes will adapt to a warmer earth. The science involves physics and chemistry of aquatic ecosystems as well as many other fields of inquiry.  Those who fish have already observed changes in their catches as warm-water fish are increasing observed in northern latitudes or high elevation waters.  Managing fish in a warming world will prove to be extremely complicated as fish re-distribute or adapt to the changing conditions.  

Some changes are already evident.  For example, Neala Kendall, Gary Marston, and Matthew Klungle, from the Washington Department of Fish and Wildlife, reported on the decline in ocean survival and abundance of Steelhead Trout (anadromous Oncorhynchus mykiss), raising concerns about long-term viability of stocks in the Puget Sound and south.  However, over the study period, temperature does not have a simple relationship to smolt survival.  This region has also undergone an ecosystem shift of the past several decades leading to demersal fish declines and increases in harbor seal Phoca vitulina and harbor porpoises Phocoena phocoena (both smolt predators).  Consequently, forecasting future changes will be highly uncertain depending on behavior of multiple predators. 

Perhaps fish in other smaller, inland systems will be easier to understand. In Michigan, streams with higher relative groundwater inputs are less sensitive to temperature changes and, therefore, more suitable for Brook Trout (Salvelinus fontinalis), Brown Trout (Salmo trutta), and Rainbow Trout (Oncorhynchus mykiss) (Carlson et al. 2017).   Observed stream temperatures in Shenandoah National Park were also less sensitive to air temperature due to the moderating effect of shallow groundwater inputs (Snyder et al. 2015). Consequently, these coldwater thermal refugia will become even more important in the future. Policymakers and stakeholders should map and protect these habitats to conserve salmonid populations as the climate warms. Moreover, this management action is correct no matter whether the water temperature increases 2 or 4 °C in the next 50 years.  Perhaps, the action can be generalizable to other regions (Isaak et al. 2015; Myers et al. 2017).    

However, much of the research to date assumes the species traits and other aspects of aquatic communities do not change.  Novel research to explore shifts in species traits (Ayllón et al. 2016) is necessary to realistically evaluate long-term changes in response to climate change. Evidence of evolutionary responses to climate change is limited to observations of shifts in timing of migration and spawning. 

Species distribution model predictions of probability of occurrence for the Kanawha Minnow Phenacobius teretulus and Appalachia Darter Percina gymnocephala in the New River drainage (Huang et al. 2016).  

Freshwater fishes face losses due to many factors in addition to climate change. Habitat loss, fragmentation of habitat, pollution, hydrologic alteration, invasive species, and overexploitation are pervasive issues.  Compared to salmonids, relatively little work has been done to assess the risk of climate change on other freshwater fishes. Species distribution models have been applied to fishes in the United States. Because the distributions are very sensitive to climate and land use, they may prove useful to projecting new distributional patterns given an altered climate (Bouska et al. 2015; Huang et al. 2016). In southern Appalachia, many cold and coolwater fishes on private lands are most at risk for local extirpations.  The species distribution models for two coolwater endemic fishes, Kanawha Minnow Phenacobius teretulus and Appalachia Darter Percina gymnocephala, demonstrate the importance of remaining coolwater fragments that support the only surviving populations of these species.  Similarly, some rare headwater fishes, such as the Clinch Dace (Chrosomus sp. cf. saylori), have no other cool places to move when temperatures rise.   

Clinch Dace is a headwater specialist with very limited distribution in Virginia. Photo: D.J. Orth

The Smallmouth Bass Micropterus dolomieu is a popular game species whose distribution will shift northward as thermal regimes warm.   However, the Smallmouth Bass may contract in the southern extent of its range where groundwater refugia are lacking.   In the southern parts of the range, growth is slow and summer growth may be limited by climate (Brewer 2013).   

Seasonal growth curve for Smallmouth Bass from a stream at the southern edge of the native range.  Median length at age is typically 20% longer. (Orth et al. 1983).

Pease and Paukert (2013) predicted that by 2060, the growth potential of Smallmouth Bass would increase by 3–17% due to stream warming, if not limited by food availability.  So it’s not enough to study Smallmouth Bass in isolation of its food sources.  Moreover, each stream occupied by Smallmouth Bass is different, some in very important ways.  Middaugh et al. (2016) examined potential differences in stream temperature across flow regimes as some stream will change more than others with climate change. We also cannot assume that fish won’t move.  Westoff et al. (2016) discovered that migratory behavior allowed the Smallmouth Bass to thermoregulate. Streams with large springs can moderate water temperatures in the stream during the warmest part of the year, creating thermal refugia (Westoff and Paukert 2014).  
 

Lynch et al. (2016) reviewed 31 studies that documented fish responses to climate change in inland waters of North America.  Most have dealt with the valuable stocks of Pacific salmon.  In Ontario lakes Smallmouth Bass may demonstrate enhanced recruitment, survival, and dispersal with warming temperatures.  In the arid southwest, climate change changes flow, thereby influencing reproductive phenology of fishes and reducing river-floodplain connectivity.  In the diverse streams of southeastern US, the interaction of climate change and pervasive anthropogenic influences makes it difficult to separate the interacting causes.   However, many stenothermic fishes are replaced by more eurythermic fishes. Lynch et al. (2016) make a number of recommendations for future research.  Importantly, they highlight the importance of identifying processes that buffer fishes from climate change, such as groundwater upwelling, phenotypic plasticity, and adaptive microevolution.  Research on resilience is lacking. 

Documented responses of fishes in the southeastern USA to climate change. Green arrows indicate an increase or earlier seasonal response, and gray arrows indicate a decrease or later seasonal response  (Lynch et al. 2016).

We all feel somewhat helpless in dealing with an issue as pervasive as climate change. There are really only three options: Mitigate, Adapt, or Suffer. Only humans are able to take action to mitigate for effects of greenhouse gas emissions.  If we fail to act, we must adapt. If we cannot adapt we will suffer.  When dealing with fishes, much uncertainty is to be expected as we attempt to save the fishes. We’re not sure all the ways in which fish may adapt.  However, projections of continued warming through mid-century means that extirpations of some populations will be inevitable and salmonids in particular are undergoing a global decline (Isaak et al. 2015). While the options in the Rocky Mountains include more public lands, that is not the case elsewhere.  I know, I am making dire predictions (= fear and doom).  So be it. Many stakeholders will need to be rallied to enable protection of climate refugia to ensure conservation of many cool and coldwater fishes.  Only time will tell.  Will the future climate lead to adaptations that allow fish to thrive,  or will we see inaction that leads to losses of freshwater biodiversity.
 

References

Ayllón, D., S.F. Railsback, S. Vincenzi, and V. Grimm. 2016.  InSTREAM-Gen: Modelling eco-evolutionary dynamics of trout populations under anthropogenic environmental change. Ecological Modelling 326: 36-43.

Bouska, K.L., G.W. Whitledge, and C. Lant. 2015. Development and evaluation of species distribution models for fourteen native central U.S. fish species. Hydrobiologia 747: 159. doi:10.1007/s10750-014-2134-8

Brewer, S.K. 2013. Groundwater influences on the distribution and abundance of riverine Smallmouth Bass, Micropterus dolomieu, in pasture landscapes in the midwestern USA. River Research and Applications 29:269-278.

Carlson, A.K., W.W. Taylor, K.M. Schlee, T.G. Zorn, and D.M. Infante. 2015. Projected impacts of climate change on stream salmonids with implications for resilience-based management Ecology of Freshwater fish 26:190-204.  

Feltman, R. 2017.  Don’t believe our planet is warming up?  Look at this.  Popular Science. July-August.  Accessed July 13, 2017, at http://www.popsci.com/climate-change-infographic-our-warming-planet

Huang, J., E.A. Frimpong, and D.J. Orth. 2016. Temporal transferability of stream fish distribution models: can uncalibrated SDMs predict distribution shifts over time? Diversity and Distributions 22:651-662.

Isaak, D.J., M.K. Young, D. E. Nagel, D. L. Horan, and M.C. Groce. 2015. The cold-water climate shield: delineating refugia for preserving salmonid fishes through the 21st century. Global Change Biology   21:2540-2553.  

Lynch, A.J., B. J. E. Myers, C. Chu, L.A. Eby, J. A. Falke, R. P. Kovach, T.J. Krabbenhoft, T.J. Kwak, J. Lyons, C.P. Paukert, and J.E. Whitney. 2016. Climate change effects on North American inland fish populations and assemblages, Fisheries, 41(7):346-361.

Middaugh, C.R., B. Kessinger, and D.D. Magoulick. 2016. Climate-induced seasonal changes in smallmouth bass growth rate potential at the southern range extent. Ecology of Freshwater Fish DOI: 10.1111/eff.12320

Myers, B.J.E., C.A. Dolloff, J.R. Webster, K.H. Nislow, B. Fair, and A.L. Rypel. 2017. Fish assemblage production estimates in Appalachian streams across a latitudinal and temperature gradient.  Ecology of Freshwater Fish  DOI: 10.1111/eff.12352

Orth, D.J., D.D. Oakey, and O.E. Maughan. 1983. Population characteristics of smallmouth bass in Glover Creek, southeast Oklahoma.  Proceedings of the Oklahoma Academy of Science 63:37-41.

Pease, A.A., and C.P. Paukert. 2013. Potential impacts of climate change on growth and prey consumption of stream-dwelling smallmouth bass in the central United States. Ecology of Freshwater Fish 23:336-346.

Fluvial Fishes Laboratory Review of 2015, by Don Orth

Follow the wisdom of Calvin.

As New Year’s Eve approaches, I know it’s that time to consider New Year resolutions, but resolution making is no fun.   As soon as I write a resolution, I set myself up for failure!

Instead of making resolutions, here I review highlights of the research activities of the Fluvial Fishes Laboratory for 2015. 

It is a diverse collection of papers, including  a synthesis on the Smallmouth Bass, DNA barcoding of PDUF, first record of the pughead anomaly,  human dimension of trotlining, and the Clinch Dace in the coalfields of Virginia.

For the symposium on Black Bass Diversity, Brewer and Orth (2015) wrote a summary of the Smallmouth Bass.  The Smallmouth Bass has been widely introduced in North America and is the preferred target of millions of recreational anglers.  With future projections of climate change, the range of Smallmouth Bass will show expansions and contractions.   Competitive angling, catch and release, and emerging contaminants are prevailing challenges throughout much of its range.  A person could make a career of studying the Smallmouth Bass  -- I did!

Smallmouth Bass from New River.  Photo by Paul Bugas.

You can purchase the symposium from the American Fisheries Society  click here.  

In 2013, we started a pilot study to determine if we could identify what we had been labeling as partially digested unidentified fish (PDUF) in the diets of catfish.  Zach Moran did the first test series as an undergraduate research project and we have been using the protocol from Moran et al. (2015)  every since.    The DNA barcoding approach has allowed us to identify 27 species from PDUF, including small plain-looking minnows (Hybognathus regius) and migratory species of management concern  (Alosa sapidissima, Alosa pseudoharengus, and Alosa aestivalis).

Zach Moran, currently MS student at Arkansas Tech University.

Traditional morphological approaches to identification could never provide species level identifications once the key characteristics were digested.  The success of this investigation hinged on the prior efforts of Rob Aguilar of the Smithsonian Institution to collect and archive DNA sequences for fauna of the Chesapeake Bay.  

Since 2012, Jason Emmel and Joey Schmitt have been sampling Blue Catfish from James, Pamunkey, Mattaponi, and Rappahannock Rivers of Virginia in order to describe the spatiotemporal variation in diets.  

Jason Emmel (left) and Joey Schmitt (right) have sampled over 10,000 catfishes since 2012.

Among many unanticipated findings, we began to encounter pugheaded or bulldog specimens of Blue Catfish.    Pugheadedness  (which my autocorrect wants to call pigheadedness) is a deformation of the maxilla, premaxilla, or infraorbital bones that creates a pugheaded snout and a significant underbite.  All pugheaded specimens were captured within the tidal fresh zone (0–0.5 ppt) of the Rappahannock River; no pugheaded specimens were captured in oligohaline or mesohaline waters.  Prolonged summer hypoxia may be producing these deformities in the Rapphannock River, though more research is necessary to confirm this hypothesis.

Pugheaded specimen of the Blue Catfish

Trotlining for catfish is an old tradition, and was difficult to study because trotline fishers proved very difficult to track down.  Dickinson et al. (2015) indicate that trotline fishers fish often and harvest and eat large numbers of catfish (Channel Catfish and Flathead Catfish) from the New River.  This activity that was often driven by sustenance needs earlier in their lifetimes.  Trotlining is a declining activity at a time when other pursuits, such as kayak fishing, are increasing on the New River.  This hidden fishery and the participants are among the few river users aware of the occurrence of large catfish in the New River (photo).   

Ben Dickinson with Flathead Catfish captured with trotline on New River.

In “Isolating causal pathways between flow and fish in the regulated river hierarchy,” McManamay et al. (2015) examined how river regulation affects stream fishes through reach scale changes, not always through hydrology.    The type of dam and operation has a direct influence on sediment and temperature and was most important determinant of fish assemblage characteristics. This paper was only possible by leveraging collaborative sampling efforts conducted by the Tennessee Valley Authority. 

 

Ryan McManamay with buffalofish.

In a symposium paper, “Legacy of dams on the New River,” we described the localized effects of the dams of the New River drainage.  One of these dams, Fries Dam, is the oldest dam on the New River and is currently undergoing the FERC relicensing process.  

Map of New River near Fries.

Historic postcard photo of Fries and New River.

You may review photos describing the Fries Hydroelectric project by clicking here.   

Fries Hydroelectric project can produce 5,213 kW of energy with hydraulic capacity of 2,100 cfs.   Structures include a 41 foot high x 610 foot long rock masonry dam.  Water is diverted into a canal to the powerhouse; after flows exceed the 2,100 cfs capacity, flows are spilled over the 500 foot spillway crest.  Storage capacity is very limited due to sediment deposits above the dam.   I wrote a long, detailed letter to the FERC regarding the environmental consequences of continued operation of the Fries Hydroelectric project.

 

Google Earth photo of New River above Fries Dam. Note the mid-channel island built from the trapped river sediments.  Not present in the historic postcard photo.

In a conference paper, Michael Moore and I examined the factors constraining the persistence of the Clinch Dace (Chrosomus sp. cf.saylori) in southwest Virginia.  

Clinch Dace Chrosomus sp. cf. saylori.  Photo by Isaac Szabo

 This yet-to-be-named yellow-finned minnow maintains small, fragmented populations in this rugged landscape of the coalfields of Virginia.  In November of 2015, we flew over many of these sites with Southwings and gained a better understanding of the nature of the modifications of this landscape.   Runoff over the unweathered exposed rock elevates the ionic content of the stream water, usually far beyond the tolerance of macroinvertebrates and fish.   Here are a few photos from this flight.

So I resolve in 2016 to keep doing what I did last year.  Do research and move things along.  It seems to be working just fine. 

References

Brewer, S. K., and D. J. Orth.  2015.   Smallmouth bass Micropterus dolomieu, Lacepède, 1802.  Pages 9-26 in Tringali et al. Black Bass Diversity: Multidisciplinary Science for Conservation. Proceedings of the Symposium Black Bass Diversity: Multidisciplinary Science for Conservation, American Fisheries Society, Bethesda, Maryland.

Dickinson, B.D., D.J. Orth, and S.L. McMullin.  2015.  Characterizing the human dimensions of a hidden fishery: riverine trotline fishers.  Fisheries 40(8):386-394.

McManamay, R.A., B.K. Peoples, D.J. Orth, C.A. Dolloff, and D.C. Matthews.  2015.  

Isolating causal pathways between flow and fish in the regulated river hierarchy.  Canadian Journal of Fisheries and Aquatic Sciences 72(11):1731-1748.   DOI: 10.1139/cjfas-2015-0227

Moran, Z., D.J. Orth, J.D. Schmitt, E.M. Hallerman, and R. Aguilar.  2015.  Effectiveness of DNA barcoding for identifying piscine prey items in stomach contents of piscivorous catfishes.  Environmental Biology of Fishes  99:171-176.   DOI 10.1007/s10641-015-0448-7

Schmitt, J.D., and D. J. Orth.  2015. First record of pughead deformity in Blue Catfish.  Transactions of the American Fisheries Society 144:1111-1116.