Wil Atencio – Honors Program Senior Project  
Role of Pigmentation in Zooplankton of Alpine Lakes  
Thesis: 
 Our world is full of beauty. From the awe capturing depths and tropical reefs of our 
expanse ocean tethered to the origin of all life, to the rolling sand dunes of arid deserts and 
snowcapped mountains of alpine lakes. As diverse the landscape, so too are the organisms that 
inhabit them. Body forms and coloration patterns that have manifested in the kiln of evolutionary 
time are also vastly diverse. Of the many adaptations that have drawn human attention, none 
have been more mystifying then that of pigmentation in living organisms (Smith, 2014). 
Biological pigments are abundant in much of life on earth including animals, plants, bacteria, 
fungi, and protists. Acting in combination, these chemical compounds absorb certain 
wavelengths of light and reflect others giving each pigment its distinct color.  
Melanin, a familiar pigment, is the main pigment found in mammals, but is not limited to 
this taxon and is dispersed widely throughout the three domains of life. The two different types 
of melanin are eumelanin; producing brown and black colors, and pheomelanin; responsible for 
yellow and red colors. Melanin is produced by melanocytes; this pigment is packaged into 
granules of the epidermis determining the coloration of an organism; however, melanin plays a 
second role as biological sunscreen, as stimulation from Ultraviolet (UV) radiation can increase 
or decrease its production in response to changes in the external environment. Carotenoids are 
pigments that produce mainly yellow, orange, or red fat-soluble pigments including carotene. 
Carotenoids have antioxidative properties by deactivating free radicles and are common in 
fruiting bodies of plants, some bird and fish species, and crustaceans. Another form of pigments 
with similar antioxidant and free radicle stabilizing characteristics include mycosporine-like 
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amino acids (MAAs). These small secondary metabolites are generally produced by organisms 
when exposed to high amounts of destructive UV radiation. Additionally, MAAs boost cellular 
tolerance to desiccation, as well as combat salt and heat stress. The ubiquity of coloration that we 
perceive on a day to day basis is the result of uncountable reactions with complex molecules and 
other contributing elements (Blaney, 1952). Organism pigmentation can be under nervous or 
hormonal control and can be affected by temperature, light, and color of the surroundings 
(Blaney, 1952). However, the role of pigmentation is often unknown. From attracting mates, to 
camouflage, warnings, or protection from UV radiation, pigmentation in many animals is well 
known but for others, such as zooplankton, its role is not fully understood.  
 Plankton are a diverse assemblage of organisms that live suspended in aquatic 
environments. Zooplankton are common in almost all freshwater and marine ecosystems 
(Hansson, 2000). Permanent plankton, or holoplankton, such as protozoans and copepods, make 
daily diel vertical migrations. They play an important role in aquatic food webs because they are 
not strong swimmers and thus are easily preyed upon. In zooplankton, the expression of bright 
red carotenoid pigments has long puzzled biologists (Schneider et al. 2016). Carotenoids are a 
large family of lipid – soluble pigments, synthesized only in primary producers. Most notably is 
astaxanthin which is the primary carotenoid in crustaceans (Schneider et al. 2016; Matsuno 2001; 
Andersson et al. 2003; Rhodes 2006). It is predicted that contribution of astaxanthin for the 
vibrant red coloration exhibited by many zooplankton is applied as an antioxidant, neutralizing 
free radicals formed when the animal is exposed to the harmful rays of UV radiation (Hansson, 
2000). Furtermore, Hairston (1976) hypothesized that variation in pigmentation within and 
between populations could be explained by the photoprotective qualities of the copepod’s 
pigments (Byron, 1982; Hairston, 1979).  
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Copepods natural “sunscreen” is particularly important at the high elevations of alpine 
lakes. For at higher altitudes a thinner atmosphere filters less UV radiation and with 
approximately every 1000 meters increase in altitude, there is a 10-12% increase in the level of 
UV radiation (WHO, 2020). In addition, water in high elevation habitats of alpine lakes is clear, 
which allows UV light to penetrate to greater depths than in lower elevation lakes. Therefore, the 
idea that calanoid copepods are more darkly pigmented at higher elevations (Brehm 1938) 
appears to hold true for alpine lakes in the front range of the Rocky Mountains (Byron, 1982). 
Though true pigments such as melanin or carotenoids provide photoprotection, several other 
substances such as mycosporine-like amino acids (MAAs) also aid copepods in UV tolerance, 
and different taxa are found to use different blends of these compounds (Hansson & Hylander, 
2009). Furthermore, it is not just the level of UV radiation that determines the amount of 
photoprotective compounds incorporated by zooplankton, but other environmental factors such 
as predation and supply of these compounds also greatly contribute (Hansson & Hylander, 
2009). Thus, pigmentation in zooplankton is a phenotypically plastic trait that’s expression is 
subject to environmental cues.  
 Scientists have studied the role and function of pigmentation in zooplankton for decades. 
This topic began to generate attention in the late 1970’s and has produced an array of 
unanswered questions. Aristotle stated, “the more you know, the more you know nothing” and 
Einstein’s, “the more I learn, the more I realize how much I don’t know.” These statements 
appear to be true for understanding pigmentation in zooplankton as well.  
Hairston (1976) studied phenotypic variance of pigmentation of the copepod Diaptomus 
nevadensis across a range of environmental and predatory cues in two lakes of central 
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Washington. He found that D. nevadensis living in Lake Lenore were pale blue, clear, or only 
slightly red, while those in Soap Lake were deep red in color (Hairston, 1976). These two 
environments differ in that Soap Lake is much more saline and contained no vertebrates, while in 
contrast predatory tiger salamanders (Ambystoma, tigrinum) and greater number of aquatic 
insects were found in Lake Lenore (Hairston, 1976). Hairston (1976) documented a trade-off 
between maximum UV protection and minimal detection by planktivores: copepods containing 
high concentrations of carotenoids survived significantly better in natural intensities of visible 
light over less pigmented individuals, but salamanders form Lake Lenore consume red copepods 
in preference to pale ones (Hairston, 1976).  
 In the laboratory, Hairston (1976) conducted experiments comparing the survival of dark 
red pigmented copepods to pale copepods in natural intensities of light as well as their behavior 
in differing colors of light (Hairston, 1976). Copepods with fewer carotenoids were dead within 
five days and those with more pigment survived much longer at high intensities of light 
(Hairston, 1976). Additionally, even at low intensities of light darkly pigmented copepods 
survived significantly better than pale ones (t test, p <0.001) (Hairston, 1976). Thus, in the 
copepod D. nevadensis, carotenoids are essential for combating the harsh effects of UV 
radiation. 
A few years later in 1982, a two-part study investigated the adaptive value of carotenoid 
pigmentation in calanoid copepods and the cost of visually selective predators (Byron, 1982). 
Byron (1982) compared copepod populations by documenting the distribution of pigmented 
forms and considered the importance of water temperature, lake depth, and elevation to copepod 
pigmentation. Yearly temperature regime is directly related to elevation and has been thought to 
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be substantially important in explaining variation in copepod pigmentation as copepods are most 
darkly pigmented in the coldest lakes (Byron, 1982). Byron (1981) showed that the metabolism 
of pigmented copepods is stimulated by illumination. Therefore, up until this point in time, 
photoprotection (Hairston, 1976) and metabolic stimulation (Byron, 1981) were the two best 
experimentally supported hypotheses explaining variation in copepod pigmentation (Byron, 
1982). Proceeding research has focused on the role of zooplankton body size and overall 
visibility as important determinants of community structure and population dynamics for 
individual species of zooplankton (Byron, 1982).  
 Byron (1982) found that pigment intensity was correlated with elevation, water 
temperature, and maximum depth. Specifically, he found an increase of pigmentation in 
copepods with increased elevation, and a decrease with both maximum depth and water 
temperature (Byron, 1982). Increased pigmentation with increased elevation is well-documented 
in many terrestrial animals and is thought to facilitate UV- protection, thermoregulation, and 
increased metabolic rate (Byron, 1982). It is still uncertain whether this is the case for copepods 
but is thought to be related to photodamaging irradiance or temperature regime (Byron, 1982). 
The negative correlation between pigmentation and maximum lake depth may be due to 
behavioral photoprotection, such as vertical migration in the water column because in deep lakes, 
zooplankton can escape to deep water to avoid UV exposure (Byron, 1982). Negative correlation 
between water temperature and pigmentation was hypothesized to provide metabolic facilitation 
through solar illumination (Byron, 1982). Though important, elevation, water temperature, and 
maximum depth are not the only factors contributing to the level of pigment incorporated by 
copepods. Fish also inhabit these waters and are visually selective predators. In lab experiments, 
trout selectively ate the most darkly pigmented copepods when given a choice between 
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individuals that vary in pigmentation intensity (Byron, 1982). In addition, field observations 
comparing the gut contents of trout that are known to naturally coexist with pigmented copepods 
showed that they were highly size selective (Byron, 1982). This suggests that trout eating 
zooplankton ate the largest members of each zooplankton species and may have also been eating 
the most visibly pigmented (Byron, 1982). Findings from this study only begin to illuminate the 
complex interactions of physiological and ecological mechanisms determining the adaptive 
significance of zooplankton pigmentation.   
 Where both UV radiation and predation are intense, zooplankton face a critical tradeoff: 
to be pigmented and thus protected from UV, increases the risk of predation, yet to be 
transparent reduces the risk of predation but increases exposure to UV radiation (Hansson, 
2000). With this delicate balance of pigmentation in the presence of planktivores, Hansson 
(2000) showed that the level of pigmentation in copepods is close to ten times higher in lakes 
without predatory fishes than where fishes are present. Just the scent of a predator alone caused a 
10% decrease in pigmentation after only four days, further suggesting that pigmentation in 
copepods is an inducible trait (Hansson, 2000). High elevation alpine lakes, where fish predators 
are present in some lakes but not others, provide the opportunity to test the potential tradeoffs in 
those factors influencing pigmentation of the zooplankton inhabitants. In a survey of 16, relation, 
high latitude and altitude Arctic lakes, the mean pigmentation of zooplankton was more than 
seven times higher in lakes without fishes compared to those with fish (Hansson, 2000). To 
contrast the effects of fish predators with light level, Hansson (2000) exposed copepods from one 
population to high light stress or low light stress crossed with the presence or absence of a 
predator. Pigmentation was rapidly adjusted to the present risk of light cue or predator exudates 
within the lifetime of an individual (Hansson, 2000). Additionally, UV radiation may be less of a 
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problem in deep lakes because zooplankton can migrate to deeper depths to avoid UV radiation 
during the day. However, in lakes without fish, zooplankton do not need to adjust their 
pigmentation because there is no chance of encountering a visually selective predator, allowing 
individuals to remain darkly pigmented regardless of lake depth (Hansson, 2000). This study 
suggests that direct consumer-prey interactions are important in shaping aquatic food webs, but 
olfactory reception of chemical cues exuded by a consumer (kairomones) are the main 
informative cue for prey (Hansson, 2000). From an evolutionary perspective, adaptations arising 
from the use of a multitude of different sources within a habitat are likely to be crucial fitness 
variables (Hansson, 2000). 
In another study of an Arctic lake, authors studied melanin pigmentation in the planktonic 
crustacean Daphnia relative to UV transparency in ponds and lakes of Finnish Lapland (Rautio 
& Korhola, 2002). The penetration of UV radiation in lakes is largely known to be a function of 
the concentration of dissolved organic carbon (DOC) (Rautio & Korhola, 2002). Most waters 
situated above the tree line in the study region (Fennoscandia) are poor in both allochthonous 
(watershed-derived) and autochthonous (originating within the lake) DOC because of poorly 
developed soils, sparse terrestrial vegetation, and low phytoplankton production (Rautio & 
Korhola, 2002). For zooplankton residing in these shallow (mean < 5m) waters, UV can 
penetrate to the bottom, therefore increasing mortality of these high-latitude open-water fauna 
(Rautio & Korhola, 2002). Thus, it is not surprising that all recorded pond populations of 
Daphnia were melanized, with the level of pigmentation being highly variable. Melanin 
concentrations were highest with low DOC because UV light can penetrate greater depths under 
these conditions. Some variability in pigmentation may be due to shallow depths of lakes 
(>.05m) lacking refugia of depth. Thus, in these lakes, Daphnia were highly melanized despite 
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high DOC (Rautio & Korhola, 2002). Different molt phases of individuals during sampling 
periods also contributed to variation in pigmentation. Molting is energetically costly for 
crustaceans and the amount of pigments incorporated in the new exoskeleton can be either a 
short-term response to high levels of UV or a genetic trait (Rautio & Korhola, 2002). In the 
Lapland Artic region daylight can last for 24 hours during summer months, yet ponds above the 
tree line are still covered by ice and snow which effectively absorbs and reflects radiation 
(Rautio & Korhola, 2002). Under the ice melanin concentrations were negligible but increased 
immediately following ice break-up and decreased toward fall with declining radiation (Rautio & 
Korhola, 2002). Zooplankton would likely not tolerate the fluctuation of UV radiation at these 
high latitude systems without the plastic and protective properties of pigments, allowing them to 
simultaneously account for predatory and environmental stress during snow and ice melt because 
of high dilution, pH decline, and increasing sunshine hours (Rautio & Korhola, 2002).  
 UV radiation undoubtably is, and has always been, a strong selective force in ecological 
communities of zooplankton (Hansson & Hylander, 2009). Morphological protection of this 
form may either be present throughout the organism’s lifetime or induced when needed as a 
phenotypically plastic trait. There are three basic ways to reduce damages caused by UV 
radiation (Hansson & Hylander, 2009). Avoidance behavior that includes diel vertical migration 
to deeper water, preventing UV damage with photoprotective compounds, such as pigments, and 
repairing damage via photo-enzymatic repair. The latter requires light of lower wavelengths and 
nucleotide excision repair that involves being active in the darkness (Hansson & Hylander, 
2009). DNA damaged by UV radiation may be repaired via the use of the enzyme photolyase in 
combination with photo repair wavelengths of UV-A to reverse the UV-B induced production of 
cyclobutene pyrimidine dimers (Hansson & Hylander, 2009).  
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The second way to reduce UV damage is by incorporating photoprotective compounds 
such as carotenoids, melanin, and MAAs (Hansson & Hylander, 2009). Melanin’s and MAAs 
function mainly as sunscreens, dissipating solar energy as heat, while carotenoids are strong 
antioxidants functioning mainly as scavengers of photo-produced free radicals (Hansson & 
Hylander, 2009). Because zooplankton cannot produce carotenoids or MAAs, they accumulate 
these pigments by consuming phytoplankton. Carotenoid incorporation is plastic, increasing with 
UV radiation (Hansson & Hylander, 2009). Carotenoid concentration varies seasonally, with 
generally lower concentrations during summer months coinciding with intense fish predation and 
relatively higher in spring with increased UV threat after winter ice break up (Fig. 1; Hansson & 
Hylander, 2009). MAAs are another group of photoprotective compounds that, unlike 
carotenoids, are invisible in visible light. In addition to protection from UV, MAAs may also 
play other beneficial roles including antioxidant effects, easing salt stress, and changes in 
internal nitrogen storage (Hansson & Hylander, 2009). In contrast to the other pigments, melanin 
can be synthesized directly by zooplankton. Melanin is deposited below the epicuticle in the 
pigment layer of the carapace and in the head to help protect antennae and may be important in 
light detection (Hansson & Hylander, 2009). 
 Prey organisms gather information from their environment by being receptive to 
chemicals exuded by predators, which induces a defense. Because both predation and UV vary 
spatially and temporally, zooplankton pigmentation should be highest in locations where UV 
penetration is high and predation pressure is low (Hansson & Hylander, 2009). Overall, photo 
enzymatic repair, responses in pigmentation, and behavior may function as complementary traits 
and together constitute a variety of tactics to account for the tradeoff between UV radiation and 
threat to predation (Hansson & Hylander, 2009). 
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Figure 1. Schematic illustration displaying pigmentation incorporated among individual 
copepods to account for the tradeoff between UV protection, and vulnerability to predation. 
 In both arctic and boreal alpine ecosystems, freezing temperatures, thick snow cover, and 
frozen bodies of water present some of the most challenging seasonal variations endured by 
organisms. For zooplankton, little is known about their behavior or physical characteristics under 
the ice because it has rarely been studied. Schneider and colleagues (2016) demonstrated that the 
calanoid copepod Leptodiaptomus minutus was most colorful in mid-winter. Coloration was due 
to carotenoid pigments identified as antioxidant agents for UV photoprotection. How can this be? 
If carotenoid incorporation, or incorporation of any other photoprotective compounds are 
primarily to protect against UV, then why are these organisms their most vibrant when little to 
no UV radiation is present under the ice? This result contrasts with Rautio & Korhola (2002) 
who found that melanin pigmentation under the ice was negligible in arctic lakes of Finnish 
Lapland. One clue is that the pigments were chemically associated with fatty acids, the major 
constituent of lipids (Grosbois et al. 2017). In winter these fat reserves were easily detectable in 
zooplankton as large droplets of lipids (Grosbois et al. 2017). The antioxidant properties of the 
pigments are likely essential in preventing the peroxidation of stored lipids in the zooplankton. 
As cited in Valko et al. (2016), copepod colors in the winter might thereby preserve the highly 
valuable fatty acid molecules from oxidative stress (Grosbois et al. 2017; Schneider et al. 2016).  
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 Schneider et al. (2016) groundbreaking paper challenges the proposed driving role of UV 
radiation and seeks to examine the mechanistic connection between UV radiation and seasonal 
patterns of copepod carotenoid pigmentation (Schneider et al. 2016). In this study carotenoids, 
fatty acid content, and reproduction of L. minutus along with UV radiation exposure, water 
temperature, phytoplankton pigments, and fish predation of boreal lakes was examined for 18 
months covering two winter seasons (Schneider et al. 2016). No previous studies had explicitly 
focused on changes in copepod carotenoids relative to seasonal changes in the environment, 
including the ice-covered winter period. These lipid-soluble pigments are synthesized only in 
primary producers and are most notably converted to astaxanthin, which is the primary 
carotenoid among crustaceans. Copepod carotenoid pigmentation was evaluated both as total 
astaxanthin content and as rate of change (Schneider et al. 2016). The latter was introduced to 
assess how copepods respond to environmental drivers by increasing or decreasing carotenoid 
content (Schneider et al. 2016).  
 Total concentration of copepod astaxanthin reached its maximum in mid-winter and 
declined steadily throughout spring and summer until a minimum was reached in late 
summer/early fall (Schneider et al. 2016). The rate of change was highest in in late fall and was 
strongly negative in March, April, and September. Carotenoids in copepods were comprised 
mainly (>99%) of three forms of astaxanthin: free astaxanthin, monoesters and diesters, 
accompanied by traces of alloxanthin (Schneider et al. 2016). The concentration of total fatty 
acids was highest in winter but showed an additional maximum in July-August which is thought 
to coincide with the presence of juvenile stages (Schneider et al. 2016). Predation by young-of-
the-year (YOY) Brook Trout was highest in August to early October when water temperatures 
were warmest. Interestingly, it was found that the rate of change of astaxanthin total was 
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negatively correlated with L. minutus egg ratio, suggesting transfer of carotenoids to eggs, while 
high abundance of phytoplankton in the water allowed for astaxanthin accumulation by both 
juveniles and adults (Schneider et al. 2016). Conclusively, the main variables contributing to 
seasonal copepod pigmentation were copepod fatty acid content and YOY predation, which 
accounted for 72% of total fluctuations observed in copepod astaxanthin content.  
The Schneider et al. (2016) study revealed that seasonal patterns in copepod carotenoid 
concentration in boreal lakes of high UV radiation may not be explained by photoprotection 
alone since the astaxanthin content of copepods in this study were inversely correlated to UV 
exposure and unrelated to underwater irradiance (Schneider et al. 2016). Surviving harsh winter 
conditions requires accumulation of energy reserves that takes place either by gathering food, 
that will be ingested during winter, or by accumulating body fats before winter has begun 
(Grosbois & Rautio, 2017). As phytoplankton assemblages in these lakes decline upon the arrival 
of winter, aquatic consumers must accumulate some form of energy reserve or find alternative 
heterotrophic sources of energy to ensure their survival (Grosbois & Rautio, 2017). Furthermore, 
because astaxanthin in copepods was closely related to their fatty acid content, results from 
Schneider et al. (2016) suggest that astaxanthin was accumulated together with lipids during 
periods of high-quality food abundance. Therefore, because the source of pigments, primary 
producers, are absent or are at very low quantities over winter months, it is plausible to conclude 
that carotenoid uptake was coupled to lipid accumulation rather than directly to food 
concentration.   
 To summarize, the accumulation of carotenoids by zooplankton is not always driven by 
UV exposure. Instead, the carotenoid astaxanthin may be used for other purposes than 
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photoprotection, such as antioxidant protection to prevent fatty acid oxidation when 
accumulating lipid reserves (Schneider et al. 2016). The seasonal correlation of esterfied 
astaxanthin amid fatty acids, suggests that astaxanthin reserves are accumulated concurrently 
with fatty acids during periods of high food abundance (Schneider et al. 2016). These reserves 
are then depleted during egg production, assuming to be due to the transfer of both lipids and 
carotenoids to eggs (Schneider et al. 2016). Such dynamics of seasonal reserve, accumulation, 
and investment into reproduction do not depend on UV exposure. Thus, they may affect 
carotenoid accumulation in any system where overwintering zooplankton experience resource 
scarcity and could potentially be overridden by other photoprotective functions in highly UV-
exposed systems (Schneider et al. 2016).  
 I first became interested in the topic of pigmentation in zooplankton because Lindsey 
Boyle, a graduate student in the Zoology and Physiology department was seeking a field 
assistant to help with collecting zooplankton in winter from frozen lakes in the Snowy Range. 
She proposed to examine pigmentation of zooplankton in the alpine lakes of the Snowy Range 
monthly throughout seasons and along elevation gradients. Schneider et al. (2016) and multiple 
other zooplankton studies motivated Lindsey’s work, which seeks to determine if pigmentation 
of zooplankton in alpine lakes is constant with Schneider et al. (2016)’s work in boreal lakes. 
Her study assesses multiple forces affecting zooplankton pigmentation across seasons, in contrast 
to most previous studies that made observations over shorter time scales or under laboratory 
conditions.  
 Lindsey sampled zooplankton in both fish inhabited and fishless alpine lakes every four 
weeks over the entire year. These lakes varied in depth, elevation, and ice thickness. A hand agar 
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was used to access the water column and samples were collected using a plankton net and 
Nalgene water bottles. Water samples were taken from the top meter of surface water using an 
integrated water sampler. Additionally, the conductivity and water temperature were taken with a 
sonde (Yellow Yellow Springs Instruments, Pro Plus). All zooplankton were identified and 
counted with a microscope. Pigment extraction has not happened yet, but she will extract and 
measure pigment levels with high performance liquid chromatography.  
 My contribution to Lindsey’s project started in the fall of 2019. I assisted Lindsey in 
taking up gear and sampling zooplankton for data collection. We took turns manually drilling 
holes in the ice and clearing them of ice shavings so that we could lower the plankton net into the 
lakes. I helped collect and filter zooplankton and take other additional measurements. Through 
trial and error, we collected an abundance of these animals for laboratory ID and pigment 
extraction. I helped count and identify zooplankton samples, but a vast majority was done by 
Lindsey. At times, unfathomable winds and white-out snow conditions prevented us from 
accomplishing these tasks. In one instance the ice agar was not sharp enough to drill the hole, so 
we were not able to collect any zooplankton. It wasn’t all bad, however, as most of the time we 
were successful, and the experience and views were quite pleasant. On a few occasions the 
Forest Service gave us a lift halfway to the lake in a snow cat, an experience I will never forget. 
We once rented snow trekkers from the outdoor program that are essentially a ski-snowshoe 
hybrid. Though these were a new and fun experience, we found going downhill to be quit 
challenging leading to many wrecks and laughs. My thesis, working with Lindsey, and college in 
general has taught me a lot about hard work, determination, and getting out of my comfort zone. 
I have grown as a person and hope to continue prospering to reach all my goals and aspirations in 
life. 
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My work contributes to the field of zooplankton pigmentation because I have established 
an overview and comparison of previous studies and novel findings attributed to the variation of 
pigmentation observed in zooplankton. There are many factors to consider when assessing the 
driving forces of such biological processes. Some of which may vary between lakes in the same 
mountain range or be similar though they are on opposite sides of the world. Therefore, many 
questions still arise as to how zooplankton adapt and evolve to such extreme fluctuations within 
environments. How widespread are actively overwintering zooplankton in lakes (Grosbois & 
Rautio, 2017)? Do different lipids sustain different activity during the winter? Ecologically, what 
is the significance of the active and colorful zooplankton community in lake food webs? 
Zoologist, biologists, and lake ecologists are only beginning to study life under the ice in an 
attempt to answer these questions, responding to an urgent need for further research with a focus 
of under-ice assemblages of zooplankton and ecosystem dynamics (Grosbois & Rautio, 2017).  
Uncovering what we now know about pigmentation in zooplankton has only propelled 
further ideas and studies to develop, testing variables and biological mechanisms used by 
zooplankton that we never previously attributed to their plastic pigmentation. This will continue 
to further our understanding of the role of pigmentation in zooplankton of alpine lakes especially 
and perhaps give us an advanced understanding of the behavior and physiology of zooplankton 
across a variety of different habitats and ecosystems.  
  
 
 
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Schneider, T., Grosbois, G., Vincent W.F., & Rautio, M. 2016. Carotenoid accumulation in 
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