Synchronized Shedders? Trilobites Molting Patterns and Implications on Defense Strategy

Synchronized Moulting Behavior in Trilobites from the Cambrian Series 2 of South China

Alejandro Corrales-García, Jorge Esteve, Yuanlong Zhao,  and Xinglian Yang

Summarized by Makayla Palm

What data were used? Slabs of trilobites found from Cambrian-age rocks in South China were discovered in large clusters of several hundred individuals. There were several species represented within these clusters. Were these full trilobites? These fossils did not have a cephalon, or a protective head “shield” that concealed sensory organs, indicating they were molts, or leftover exoskeletons that had been shed off after a molting cycle (much like modern lobsters and tarantulas, which belong to the same phylum as trilobites, Arthropoda). All of the trilobite specimens were measured; scientists planned to use this data to test the hypothesis that these specific taxa, or groups of trilobites, had the same molting patterns as other members of Arthropoda. 

Methods: Scientists recorded measurement data to estimate average specimen size for each species. Researchers performed other data analyses, as well, such as: if different species were clustered together (or not), the orientation of the trilobites, or the way they were facing (e.g., – dorsal, or back, up or down) to learn more about how they were buried, and how differently the exoskeletons had molted, by observing how they deviated from a typical, complete trilobite.

Results: The sizes for all the species were all relatively small, which is evidence to support the idea they had gathered to molt for protection. If they had clustered together for reproduction, various sizes would have been found together. The smaller sizes indicate these may have been juveniles that stuck together for strength in numbers, which is observed in modern-day arthropods. The researchers observed all of the previous molting patterns found in other trilobites in these four trilobite species, confirming a wide variety of species molted in similar ways. They also observed that each species was clustered together and they had not intermixed with one another. The fact that these species did not intermix implies group synchronization, which is found in extant species of arthropods as a defense mechanism. It is inferred that these trilobites coordinated their molts in order to protect themselves during the vulnerable process of molting, which leaves their softer insides more exposed to predation until their new exoskeleton hardens.

There are ten known ways of trilobite molting, with various parts of the body either missing or displaced, depending on the growth stage the trilobite was in or if the trilobite needed to replace any body parts.There are two rows of five configurations. All of these configurations are with a dorsal view. The first five configurations are where different parts of the body are omitted, but not disfigured or displaced. Configuration A is missing the top of the head that extends around and almost touches the side. Configuration B is missing the inner part of the head and retains the outer rim of the head. Configuration C is missing the segment that connects the head with the thorax. Configurations D and E are missing body segments in the thorax. Configuration F has the crown of the head displaced under the thorax. Configuration G is missing the crown of the head and the connection between the head and thorax. Configuration H has all parts, but they are disconnected. Configuration I has the head bent forward on top of the thorax. Configuration J has the crown facing down and behind the thorax.
There are ten different molting configurations found within the cluster of trilobites found in all species of the study. The molting patterns differ in where a segment of the exoskeleton is missing, a body part displaced, or a body part that has been shifted. For example, some of the head pieces have been removed or displaced to lay behind the rest of the body. There are pieces of the thorax missing in some, or shifted relative to the rest of the body. These different configurations represent the known molting patterns of trilobites and show clear similarities in molting patterns with extant arthropod species. The relatively small size of the trilobites indicates they may have banded together for protection against predators, and molted in groups for strength in numbers.

Why is this study important? Several different trilobite types in Cambrian strata were found clustered together, but the fossilized remains weren’t complete trilobites. These were molts or leftover exoskeletons they had outgrown and shed. Molting is a common behavior in living arthropods today, and there are certain ways these creatures can molt. Several of these molting patterns have been described and documented previous to this study in other trilobites, and this study expanded on knowledge of molting patterns. This study also shows evidence that trilobites may have worked together in synchronized molting as a protection mechanism.  

The big picture: Fossils like these preserved here, along with modern analogs, can help us understand more about the behavior of long-extinct organisms.  Evidence from extant species of arthropods today has shown groups of species molt together as a defense mechanism, and the hypothesis of this paper was that the four tested groups of trilobites did the same thing. By finding the different species separated in different groups with various molting patterns, the researchers were able to conclude these trilobites likely synchronized, or coordinated molting together in groups. 

Citation: Corrales-García, A., Esteve, J., Zhao, Y., & Yang, X. (2020). Synchronized moulting behaviour in trilobites from the Cambrian Series 2 of South China. Scientific reports, 10(1), 1-11.

Wetlands and Wildlife

The relationship between biodiversity and wetland cover varies across regions of the conterminous United States

Jeremy S. Dertien, Stella Self, Beth E. Ross, Kyle Barrett, and Robert F. Baldwin

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? Using data from the National Wetlands Inventory and the National Land Cover Database, the researchers modeled wetland cover for the conterminous (continental 48) United States and collected estimates for how much wetland existed in the continental U.S. in 2001 and 2011. From various other sources they compiled more information essential to understanding wetland habitats: which animal species live in the areas and their distribution/ranges, the average temperatures and precipitation levels of the wetlands, and the elevation or altitude. 

Methods: The maps showing the ranges of the endemic (native) birds, mammals, reptiles, and amphibians were accumulated into one endemics raster (a grid where each cell represents a piece of data) for analysis. Each cell represented a 10×10 km area, so the estimated amount of wetland cover (in hectares) per every 100 km² was the focus. Wetlands smaller than 0.01 hectares and large bodies of water were removed from the data to prevent flawed or biased results. 

To calculate wetland change, the researchers subtracted the wetland cover estimates of 2011 from the 2001 coverage to calculate the 10-year change. To calculate per-cell percentage change of wetland cover they divided the 2001 wetland cover per cell by the estimate of 10-year wetland change.

Results: The proportional wetland cover varied from 0.0 to 5841.0 ha/100 km² across all 48 states considered. The area with the most wetland cover was the southeastern U.S. including portions of Alabama, Georgia, Florida, and North and South Carolina. The three areas with significant percentages of wetland cover were Florida, particularly in the northern part of the state and in the Everglades National Park, the floodplain of the Mississippi Valley, and parts of northern Minnesota and Wisconsin. The western U.S. had the least wetland cover with areas of less than 100 ha/100 km² in the Mojave and Sonoran Deserts. Between 2001 and 2011, wetland coverage decreased by approximately 481,500 ha. The highest percentage of loss was in the Great Plains region.

The models for the four animal groups showed regional hotspots where proportional wetland cover was positively or negatively correlated with species diversity. There was no consistent relationship between wetland cover and species variety across the entire 48 states, but on a regional scale there were correlations. Birds, reptiles, and endemic species groups all showed large areas of positively significant correlation with wetland cover while mammals and reptiles showed relatively larger negatively significant correlations.

Color-coded map of the United States. Yellow indicates a larger number of endemic species (83 is the highest amount). The colors change to shades of green, blue, and purple, with dark purple being the least amount, one species. The majority of the map is purple and blue. The southeastern region shows the most biodiversity, and all the yellow patches are in Florida, Georgia, South Carolina, Alabama, Mississippi and Louisiana.
Cumulative map of endemic amphibian, bird, mammal, and reptile species in the conterminous U.S. Note that the states with the most endemic species are Florida, Georgia, South Carolina, Alabama, Mississippi, and Louisiana.

Why is this study important? While wetlands all over the United States should be protected, certain areas are in a more delicate balance than others simply due to how many organisms rely on them. Knowing which regions have the most wetland cover and biodiversity can indicate where efforts of conservation and restoration should be particularly focused to have the most valuable impact. 

The big picture: Wetlands are important habitats and migratory stops for wildlife and provide essential services to the environment including carbon sequestration, water filtration, nutrient retention, and flood mitigation. The loss of wetlands in the U.S. to human activity and urban development has already been significant. The prevention of further damage has to begin with providing clear and concise information about the wetlands and the resources they provide. 

Citation: Dertien JS, Self S, Ross BE, Barrett K, Baldwin RF (2020) The relationship between biodiversity and wetland cover varies across regions of the conterminous United States. PLoS ONE 15(5): e0232052.

Jamie Stearns, Fossil Preparator and Museum Educator

Tell us a little bit about yourself. My name is Jamie Stearns. I am 34 years old, a trans woman, interested in gaming, sci-fi and fantasy, and have been with my spouse Mariah for six years. I volunteer at the Arizona Museum of Natural History as a fossil preparator and a museum educator.

Foreground: Jamie standing in a fossil gallery wearing a blue shift and holding a purse. Background: a mounted tyrannosaur skeleton in an action posture.
Jamie with a tyrannosaur.

What kind of scientist are you and what do you do? As a fossil preparator, I spend a lot of time preparing fossils in the laboratory after they have come in from the field. This typically involves opening up plaster field jackets used to transport specimens to the lab and carefully separating the specimens inside from the surrounding rock, or matrix. This can involve anything from dental picks and brushes to air scribes. To preserve specimens for the museum’s collections, I use special types of glue to stabilize anything fragile and to put broken pieces of a specimen back together. Sometimes support jackets have to be constructed for irregularly-shaped specimens. I also screen wash matrix from the fossil sites and sort through it for microfossils, and I occasionally help out in the field as well.

As a museum educator, I explain the significance of specimens to visitors and answer any questions they may have about what they are seeing. I have a number of smaller specimens used in demonstrations where visitors can handle and discuss them; everything from a Tyrannosaurus rex tooth cast to an ammonite preserved in mudstone.

Jamie sitting at the base of a mastodon skeleton mount in a large room.
Jamie with a mastodon.

What is your favorite part about being a scientist, and how did you get interested in science? My interest in paleontology goes back to when I was only five years old. My family had just moved to the Washington, DC area a few months before, and I was in preschool when February 1993 was declared to be “Dinosaur Month”. In the process, I got my hands on a copy of National Geographic with a double feature on dinosaurs. I was immediately fascinated by all these different creatures with their sharp teeth, long necks, armor plates, horns, and crests and wanted more. I eagerly read through all the dinosaur books at the library and watched the latest documentaries, absorbing as much knowledge as I could find. My family took me to see the fossil halls at the Smithsonian afterwards where I could actually see them in person, too. At one point I even called my kindergarten teacher out when she said that dinosaurs were cold-blooded. Although I was exclusively a dinosaur nerd throughout primary school, I worked at a lot of different museums and fossil sites in and shortly after college, which helped me see a bigger picture; as amazing as dinosaurs were, no less impressive were the reptiles that shared the earth with them, or the variety of mammals that came later.

This interest led me into a bit of an uncomfortable spot with some of the Evangelical Christian groups I was with in middle and high school, where I initially thought nobody could possibly believe in a literal six-day creation due to all the evidence against it. It turns out, of course, that most of them did believe that the geological timeline I had come to memorize was nothing but lies, made up by people because they didn’t want to believe in God. I couldn’t accept this, and this was only the first point on which I started to disagree with them. I never lost my faith despite that, but given everything I eventually found out about myself, I am not sure what they would think of me now.

Jamie and Mariah with a hadrosaur bone that Jamie prepared.

My favorite part of working at the museum is when I discover something new in the field or uncover something in the lab for the first time. I’m the first person to see this thing in millions of years, and that’s pretty special. I also enjoy being able to share my knowledge and passion about prehistoric creatures and their environment with visitors and seeing them learn new things they hadn’t thought of before.

How does your work contribute to the betterment of society in general? My work in fossil preparation helps scientists find out more about what the world of the past was like and what kinds of animals lived back then, and screen washing for microfossils can reveal details of the environment of the time as well. This adds to our understanding of how the earth’s climate changed over time and how life evolved in response to that.

I would like to hope that I have made an impact on those visiting the museum as well. Many people come in with preconceived ideas about prehistoric life and earth’s history, and what I do helps challenge those ideas and get people to think more critically about what they may have read or seen.

Jamie standing behind a table that has a series of fossils set up on display for an educational event. The back wall has a series of educational posters related to natural history.
Jamie doing a fossil demonstration.

What advice do you have for up and coming scientists? Get involved in volunteer work in your field when you have the opportunity. There is probably a local institution of some kind that deals with what you’re interested in, so see if they have any opportunities. It’s an excellent way to get a feel for what working in your field is like, and you can make connections with experts who have already been working in the field too. Don’t lose sight of your goals, and never stop learning.

New Species of Carnivorous Plant Discovered

First record of functional underground traps in a pitcher plant: Nepenthes pudica (Nepenthaceae), a new species from North Kalimantan, Borneo

Martin Dančák, Ľuboš Majeský, Václav Čermák, Michal R. Golos, Bartosz J. Płachno, Wewin Tjiasmanto

Summarized by Michael Hallinan 

What data were used? 17 different specimens of a new species of pitcher plant (Nepenthes pudica) were examined from 5 different sites across the North Kalimantan province of Indonesia. This region is mountainous and covered with extensive rainforest.  The specimens were photographed, sampled, and then fixed in ethanol or dehydrated in preparation for further evaluation. In addition to these specimens, prey samples were also collected, including earthworms, insects, and insect larvae from inside the plants themselves. These were fixed in formaldehyde and further documented similar to the plant itself. 

Methods: The specimens went through three main stages of examination. First, the plants were photographed and compared to drawings and descriptions of other species within the genus Nepenthes. Next, the trap parts (used by the carnivorous plant to trap and collect prey) were examined under an electron microscope. Lastly, some of the traps were poured out and found to consist of insects, mites, and ticks. This content was identified and signs of digestion were documented, allowing the content to be labeled as either prey, or just organisms that live in the sediment and were unintentionally collected. 

Results: Typically the genus Nepenthes catches prey through a pitfall trap which has their prey fall into a pitcher-shaped cavity formed by a cupped leaf, where the plant then breaks them down through digestive juices. However, these traps are usually above ground or in water, with this trait only found in other genera such as Genlisea, Philcoxia, and Utricularia, though they use different entrapment strategies. The discovered species (Nepenthes pudica) features underground pitchers, where it catches and consumes prey such as mites, leaf litter-inhabiting beetles and ants. It is the first known pitcher plant species to use pitfall traps within the subterranean environment, containing traps of comparable size to the rest of the genus despite its subterranean nature. Typically, the pressure needed to form a cavity in soil is unsuitable for pitchers like these, which not only makes this find unique, but it also challenges our understanding of carnivorous plant feeding strategies.

Figure detailing four different images of the pitchers of the new species (Nepenthes pudica). The first image shows detail of the lower pitchers excavated from the soil. The second shows the lower pitchers under tree roots, while the third shows lower pitchers underneath a moss mat. Lastly, the fourth picture shows a set of lower pitchers extracted from a soil cavity. Generally the pitchers have a slightly curved opening with a fairly consistent width along the length of the pitcher. In addition, the pitchers feature a dark slightly purple red, with a green or white interior of the pitcher. Each of the pitchers is 7-11 cm in length and 3-5.5 cm in width.
Figure detailing four different images of the pitchers of the new species (Nepenthes pudica). The first image shows detail of the lower pitchers excavated from the soil. The second shows the lower pitchers under tree roots, while the third shows lower pitchers underneath a moss mat. Lastly, a set of lower pitchers extracted from a soil cavity. Each of the pitchers is 7-11 cm in length and 3-5.5 cm in width.

Why is this study important? This study is extremely important as identification is essential for protection. If we are more aware of which different species exist, we can better understand relative biodiversity as well as focus our conservation efforts. The discovery of this plant in particular allows a little bit more insight into understanding evolutionary adaptations of carnivorous plants which can potentially be applied to other plants within Indonesia’s ecosystem as well as carnivorous plants worldwide.

The big picture: 17 specimens of a new species of carnivorous plant were collected and further examined. Through a series of comparisons to known species within the genus as well as analysis of its prey and structure, it was determined to be a new species especially as a result of its unique underground traps. The traps typically seen within this genus of plants appear above ground or in water, which makes this species unique. This discovery allows us to better understand biodiversity in the region and gives us new insights into how we need to approach conservation. 

Citation:  Dančák M, Majeský Ľ, Čermák V, Golos MR, Płachno BJ, Tjiasmanto W (2022) First record of functional underground traps in a pitcher plant: Nepenthes pudica (Nepenthaceae), a new species from North Kalimantan, Borneo. PhytoKeys 201: 77-97. 

Conditions of essential desert plants

Climate change effects on desert ecosystems: A case study on the keystone species of the Namib Desert Welwitschia mirabilis

By Pierluigi Bombi, Daniele Salvi, Titus Shuuya, Leonardo Vignoli, Theo Wassenaar

Summarized by Habiba Rabiu, a student of environmental geosciences at Fort Hays State University. Habiba is interested in all aspects of environmental science and conservation & sustainability. She would like to work in educating others about those topics. In her free time, she likes to read, write, and bake.

What data were used? The welwitschia dwarf tree is a gymnosperm native to the Namib desert. It is considered a keystone species of the region, providing food, water, and shelter for the animals that live in the desert. Under the current threat of climate change, there is concern that certain parts of the welwitschia’s distribution range will no longer be suitable for their survival. 

Methods: The researchers spent ten days searching for W. mirabilis plants in the northernmost area of their traditional range. They recorded the plant locations (precise coordinates of the plant), health condition (based on leaf color to measure photosynthesis efficiency and chlorophyll content, using the classifications of good, average, poor and dead), reproductive status (whether or not the plant had cones), and plant size (diameter of the stem and leaf length) for each individual plant. Because the plants grow in clusters of four to 400, called stands, they recorded the proportion of healthy, average, poor, and dead plants in each stand, as well as the average size of the plants in each stand and proportion of reproductive to non-reproductive plants. 

Results: A total of 1330 welwitschia plants were found in 12 stands, across an area of about 215 km². The researchers found that that to be significantly smaller than what was previously considered their area of distribution. 

With regards to health conditions, most of the plants (50% total, 32–74% average in each stand) were considered ‘average’. Plants considered to be in ‘poor’ condition were 32% (range: 11–50%), those in ‘good’ condition were 10% (range: 0–30%) and seven percent of the plants were dead (range: 0–30%). Concerning reproductive status, 56% of the plants (range: 10–90% across the different stands) had cones. Size of the plants varied greatly when considered individually and in each stand. 

The overall status of the plants was considered consistent with their expected condition when taking into account the effects of climate change. The results suggested that ongoing climate change is negatively affecting the health status of welwitschia populations in the area and causing a reduction of the species’ distribution.

The black section is a squared-off area close to the northern border of Namibia with a small part of it touching the coastline. There are three red areas all relatively close to the shore, in line from north to south. Inside the black area there is a red area, and situated within that is the only blue area, which is very small compared to the black and red areas.
Larger map shows the study area (surrounded in black), the previously known species distribution (surrounded in red), and where the trees were found during the study (surrounded in blue). Insert map shows location of study, in northern Namibia.

Why is this study important? Welwitschia trees are essential to the Namib desert ecosystems and are good indicators for the overall health of the environment. Determining how they are responding to climate change could indicate what the future of the region will look like for the organisms that live there.

The big picture: While deserts are not usually thought of as teeming with life, they are important environments that house a lot of biodiversity in the form of plants and animals. The effects of global warming are and will continue to be particularly harsh on desert species. The ecosystems that exist there have to adapt to increasing temperatures that were already high to begin with, less rainfall where there was already very little, and more CO₂ in the atmosphere. These changes could greatly affect how the deserts all over the world function and whether or not the organisms that survive there will be able to continue to do so.

Citation: Bombi P, Salvi D, Shuuya T, Vignoli L, Wassenaar T (2021). “Climate change effects on desert ecosystems: A case study on the keystone species of the Namib Desert Welwitschia mirabilis.” PLOS ONE 16(11): e0259767.

New Dataset of Global Evaporative Water Loss

Evaporative water loss of 1.42 million global lakes

Gang Zhao, Yao Li, Liming Zhou and Huilin Gao

Summarized by Michael Hallinan 

What data was used?  A series of geospatial data containing information on global lakes that are over 0.1 square kilometers (approximately 328 square feet) was sourced from HydroLAKES, a database centered around mapping the global freshwater. The data included a total of 1,427,688 water bodies, of which 6715 are reservoirs. In addition to this, three sets of meteorological data from TerraClimate, ERA5, and GLDAS were used to cancel bias as each dataset was developed independently through different institutes with a wide range of input sources. Lastly, a series of lake ice coverage and lake evaporation data were obtained from the Natural Snow and Ice Data Center and previous studies, respectively. 

Methods: Using the geospatial data on lakes, a series of calculations was performed to estimate potential water loss due to evaporation of lakes and reservoirs. This was performed through calculating the change in heat stored by the body of water using the density, specific heat of water, water depth, and change in water temperature. Then an estimation of lake evaporation rate was performed using vapor pressure, net radiation, change in heat, surface area, as well as wind and other environmental data. In addition to this, further data processing occurred to account for ice coverage as well as to remove biases in satellite-sourced data caused by cloud coverage.  

Results: This study created a dataset of evaporative water loss from 1958 to 2018 containing estimates of monthly evaporative loss of over 1.42 million lakes world wide. The most notable observations of this dataset are that the long-term average global lake evaporation has increased by 3.12 cubic kilometers per year in volume (roughly 0.75 cubic miles) while the average currently is 1500±150 cubic kilometers (roughly 932 cubic miles). This trend is likely a result of three main factors: Around 58% of this increase is a consequence of increased evaporation rate, 23% is caused by decreasing lake ice coverage, and 19% stems from an increase in lake surface area. In addition to this, these three factors have an identifiable pattern in their global distribution. High-latitude and high-altitude regions such as Tibetan Plateau and northern Eurasia show amplified effects of climate change on ice duration and as a result evaporation, likely having accelerated evaporation in the future.

Global map showing a ratio of lake evaporation versus total evapotranspiration (all land evaporation plus plant transpiration, with values ranging from 0% to >30%. Most of the global land surface falls into the 3% to 6% range. Much of Canada as well as some of the western regions of the United States fall into the 6% to 10% range, with some regions of Canada being in the 10% to 18% or even 18% to 30% range. The northern region of South America is predominantly between 0 and 1% while the southern hemisphere is mainly between 3% and 6% with some regions near the upper Andes Mountains having a ratio of 18 to 30%. Africa is a mix with much of the continent varying between 0 to 1% and 3 to 6% with some of the southern and north-eastern regions having ratios between 6 to 10% and even >30% near Egypt. This is globally the area with the highest ratio. Eurasia is mainly between the 0 to 1% and 1 to 3% categories with the exception of Iraq and Iran with that region having 6 to10% up to 18 to 30% ratios appear. InFinland, Europe also begins to see this same ratio increase to 6 to 10% and 10 to 18%. Lastly, Oceania is a mix of 1 to 3% and 0 to 1% with the 0 to 1% occurring on the eastern side of Australia and the majority of the island nations.
Global map showing percentage ratio of lake evaporation versus total evapotranspiration (all land evaporation plus plant transpiration).

Why is this study important? This dataset is essential to understanding global evaporative loss and the response of bodies of water to global warming. This dataset is the first of its kind to provide long-term monthly evaporation data on a global scale. This information can be used in the context of water availability estimations as well as in climate models. Although previous studies about water evaporation have been performed, many of them focused on only a few environmental parameters such as lake surface temperature, lake and river ice, or other attributes. This knowledge will be imperative in improving our overall understanding of the effects of lake evaporation

The big picture: A dataset of evaporation data comprising 1.42 million lakes from 1958 to 2018 was formed through a mixture of geospatial, meteorological, and lake ice coverage data. This dataset is the first of its kind and can be used to better understand water availability as well as water bodies’ reaction to climate change. Lastly, through this dataset it was discovered that there is an increase in water evaporation of about 3.12 cubic kilometers per year in volume (roughly 0.75 cubic miles).

Citation: Zhao, G., Li, Y., Zhou, L. et al. Evaporative water loss of 1.42 million global lakes. Nat Commun 13, 3686 (2022).

Climate Change Threatens Salmon Habitats within the US

Climate Change Shrinks and Fragments Salmon Habitats in a Snow-Dependent Region

Daniele Tonina, James A. McKean, Daniel Isaak, Rohan M. Benjankar, Chunling Tang, Qiuwen Chen

Summarized by Michael Hallinan

What data was used? The EAARL (Experimental Advanced Airborne Research Lidar) was used to collect the majority of the data. This machine rapidly outputs green lasers through air as well as water, which collects location and elevation when the reflection of each laser pulse is detected. This machine was used to survey Bear Valley Creek, an essential Chinook salmon (Oncorhynchus tshawytscha) spawn point located in Idaho, U.S.A. In addition to this, a series of habitat suitability curves (data expressing the ability of a species to live on observed environmental conditions) from the Washington Department of Fish and Wildlife was also used.

Methods: The location and elevation data allowed the local topography to be mapped. A series of hydrologic models and climate models were applied to the region with this topographical data, allowing the researchers to calculate surface area, volume, and mean depth of nearby bodies of water which are essential for early salmon development. In addition to this, hydraulic data such as velocity of water, depth, and shear stress (stress from water moving downstream) was predicted using these models for the entire year. All the modeled hydrologic, topographic, and geologic data were compared to the habitat suitability curves allowing to predict the quality of potential habitats in regards to salmon sustainability and upbringing as well as the distribution and connectivity of these habitats for salmon. 

Results: Between 1957-2016 it was found that average water flow has declined by 19%, or about 3% per decade. High water flow is essential for salmon to migrate in and out of streams. In addition, the velocity of the water also showed a decrease of 17% with the largest drops occurring in areas where salmon spawning is most frequent. As a result of these changes in water movement throughout these streams, there also was a clear negative impact on habitat conditions. It was found that the suitable spawning area for the salmon has significantly decreased. It’s expected that future summer water flow will be 72% lower than previously which will result in an approximate 38% decrease in spawning habitat size. Overall, climate change has shown to generate more negative conditions for salmon spawning as well as future negative impacts on habitat distribution. This can potentially threaten the long-term health of Chinook Salmon within this region, especially as they are already challenged by overfishing, these conditions could permanently damage the population’s health.

A colored figure displaying spawning habitat quality distribution for chinook salmon when water flow is at 1 cubic meter per second. Values go from 0 to 1 with 1 being the highest quality and 0 being the lowest. The river meanders in a snake-like shape going from the north-eastern part of the map to the south-eastern part of the map. Much of the water near the banks of the river features a spawning quality of 0, detailed in red. However, the more central parts of the river bed tend to fall within the 0.5 to 0.6 range with irregularly distributed sections within the 0.9 - 1 range throughout the river. This means that spawning habitat quality is generally very low near the edge of the river and mediocre through much of the river with higher quality occurring only in the center.
Figure displays an approximately 0.5km long segment of the Bear Valley Creek. distribution of Chinook salmon spawning habitat quality when water flow is at 1 cubic meter per second. The higher the quality value the more favorable to spawning, the lower the value the less favorable for spawning.

Why is this study important? Climate change has been shown to pervasively affect life on earth for example by changes in temperatures. Although within recent decades more progress has been made on our understanding of the topic, much of the current research still focuses on stream water temperature while other hydrological conditions that may significantly impact species health remain understudied. This study looks at these deeper hydrological conditions within the northwestern U.S, specifically in the Bear Creek region of Idaho, which is essential for the larger salmon population across the country and the fishing industry that depends on them. By increasing our understanding of these conditions and the impact of climate change, we can react better and begin to remediate these changes to support salmon populations as well as the local and global economies that depend on them. 

The big picture: Climate change has negatively affected salmon health and populations within the Bear Creek region of Idaho, U.S.A. This has been identified previously, but is usually only looked at within the context of temperature changes. This study further explores hydrological data and how it affects salmon reproduction, such as flow, velocity, and water depth. A 10% decrease in suitable spawning spaces was identified when comparing the likelihood of use as well as a 17% drop in flow velocity which negatively influences migration among stream for salmon. All of these factors threaten salmon populations, however being able to identify these may allow us to better understand salmon health as well as how to react in terms of conservation.

Citation: Tonina, D., McKean, J. A., Isaak, D., Benjankar, R. M., Tang, C., & Chen, Q. (2022). Climate change shrinks and fragments salmon habitats in a snow‐dependent region. Geophysical Research Letters, 49(12). 

Early Risers – A Study of Early Tetrapod Locomotion

Locomotory Behaviour of Early Tetrapods from Blue Beach, Nova Scotia, revealed by microanatomical analysis

Kendra I. Lennie, Sarah L. Manske, Chris F. Mansky and Jason S. Anderson

Summarized by Makayla Palm

What data were used?  Previous research has analyzed possible moving mechanics for the first tetrapods that lived on land (i.e., a four-limbed vertebrate), but most of the conclusions were made in inference, like by analyzing footprints. The researchers of this study aimed to find more direct evidence of how these early reptiles like Tiktaalik or Ichyostega moved in order to determine what lifestyles new fossils from Blue Beach, Nova Scotia had (aquatic/land). In order to test their hypothesis, they studied the limb bones of the new fossils and living creatures like cats and platypi in order to observe how these limb bones adapted to the stresses of gravity and hitting solid ground. The scientists used 3D scans of bones from both the modern and the fossil tetrapods; the living ones had a range of lifestyles from aquatic to terrestrial, for better comparison to the fossils.

MethodsThe researchers took 3D scans and measured the volume of limb bones from eight extant (or living species) and five extinct species (the fossils from Blue Beach, Nova Scotia). This information would give them the ability to tell how, or if, these creatures walked. The extant species were studied in order to observe how and where muscles were stressed during walking (and what clues that left behind in bone) in living creatures to find what patterns to look for in the fossil specimens; this created what is called a compactness profile. The compactness profile summarizes how the different tissues in the bones react to stress over time by observing the amount of trabecular tissue in a certain part of the limb bone. Trabecular bone is a kind of bone tissue that is made of tiny plates meshed together. The trabecular tissue arranges itself where the bone experiences the most stress; this is the pattern being observed in the compactness profile. The bones from each specimen were digitally sliced in a cross-section to observe the internally visible trabecular bone. The researchers observed the trabecular bone in extant species first because their moving mechanics are known. Once they established the pattern of where the trabecular bone was in extant species, they applied it to the extinct species to determine their moving mechanics.  

Results: The trabecular bone’s location shows where the most stress is being absorbed in the bones (think of swimming and the different muscle groups used in contrast to walking- a long walk and a long swim will leave one sore in different ways.) The study shows different stress in the trabecular bone across taxa, depending on if the creature was aquatic or land-living. They concluded that the aquatic species had trabecular bone in the midshaft, or middle of the bone because they would pump their legs while swimming. Terrestrial, or land-based tetrapods, had trabecular bone around the two ends of their femurs, indicating they walked. Some of the fossil tetrapods had less dense trabecular bone than some of the extant species, but it was at the ends of the limb bone; researchers concluded these fossils would have lived a semi-aquatic life (a modern alligator is semi-aquatic, for example). Based on the results of this study, it is likely that the Blue Beach tetrapods represented a range of different lifestyles, from fully aquatic, and semi-aquatic, to fully terrestrial, as all of the patterns of trabecular bone described above were found in the different taxa. 

Twelve cross-section samples of limb bones from different species and different lifestyles are shown with the trabecular bone visible. The figure shows the semi-aquatic genera first, the Blue Beach fossils second, and the terrestrial genera last. The cross sections of terrestrial creatures have a black ring with a white center, such as Felix, Uromastyx, and Eublepharis. Semiaquatic creatures have a thinner black ring with 50% white center and 50% gray center indicating some trabecular bone presence. These creatures are the Amblyrhynchus and Ornithorhynchus genera. Aquatic creatures have an almost completely full center, indicating a significant amount of trabecular bone. The aquatic control sample was from an Ornithorhynchus. The figure also has a graph showing the levels of compactness throughout the sample. Samples with more trabecular bone have a more consistent compactness level, whereas less trabecular bone has a steeper graph. The steeper graph is reflective of the absence of trabecular tissue.
All cross sections of the femurs from this study are shown here, along with a graph showing compactness profiles, which is similar to density. Since the specimens come from different environments and lifestyles, there is an expected difference in the cross-section density. These cross-sections come from the midshaft of the limb bones, so creatures with semi-aquatic or fully aquatic lifestyles should have trabecular bone in their cross sections. Those with terrestrial lifestyles should not. For example, the feline (Felix) cross section in the bottom right corner has an open circle in the center of its cross-section, indicating no trabecular bone, which is consistent with its terrestrial lifestyle. In contrast, the Ornithorhynchus (the modern-day platypus) cross section has a lighter amount of trabecular bone, which is consistent with its semi-aquatic lifestyle.

Why is this study important? The study of tetrapod locomotion, or movement mechanics, reveals how the earliest known walking creatures lived and moved. Previous research used proposed ideas on locomotion by inferring muscle and ligament placement on the limb bones of the tetrapods. This study uses direct evidence by looking at how the limb bones react to stress to determine how these creatures moved in various environments. 

The big picture  Researchers are using tissue evidence in order to better understand how the earliest walking tetrapods walked. The tissue, or trabecular bone, helps researchers see direct evidence of walking, rather than relying on inferred information about soft tissues. The analysis of trabecular bone is direct evidence for locomotion because it is re-arranged by stresses from gravity. The ability to observe these changes in soft tissue depending on lifestyle is a definitive classification of lifestyle for these early risers. Rather than saying “these creatures had the ability to walk”, the researchers are saying, “these creatures did walk.”

Article Citation: Lennie, K. I., Manske, S. L., Mansky, C. F., & Anderson, J. S. (2021). Locomotory behaviour of early tetrapods from Blue Beach, Nova Scotia, revealed by novel microanatomical analysis. Royal Society open science, 8(5), 210281.

Lian Anderson, Paleontologist

Tell us a little bit about yourself. Hi! My name is Lian and I am a recent graduate of the University of Michigan! I am originally from Missouri but currently call Michigan home. I am in an in-between period in my life, I graduated this past spring with a degree in Earth and Environmental Sciences and a minor in paleontology and plan on applying to graduate schools this upcoming fall. Outside of science, you can find me spending my free time outdoors biking, hiking, or just sitting on a porch. I love to paint, learn about geography, and cook.

What kind of scientist are you and what do you do? My research has focused on using morphology as a tool. Morphology is the study of the shape of something, it can be applied to something as simple as a single tooth or as complex as a whole fish skeleton! As an undergraduate, I produced an honors thesis that focused on an extinct clade of echinoderms known as blastoids. I investigated whether varying ratios in blastoid’s underlying skeletal components were indicative of deeper taxonomic relationships. To do this, I first produced 3D models of specimens through a process known as photogrammetry. Once the models were produced, I then placed a set number of landmarks on each specimen, in homologous places. Once the landmarks were placed, I then ran a principal component analysis (PCA) in R. The PCA helped to determine if varying ratios in blastoid’s underlying skeletal components, taxonomic separation, and geological periods occupied distinct regions in morphospace. In addition to my work with blastoids, I have also had the opportunity to apply similar techniques to epibionts on brachiopods and jaws of nautiloids!

Outside of research, I also worked at the University of Michigan Museum of Paleontology’s (UMMP) Invertebrate Paleontology collection as a museum technician. There, I have the amazing opportunity to handle specimens in a collection of over 2 million specimens! I work with type specimens, produce 3D models, and rehouse or unpack specimens. Museums typically only show a small fraction of their collection in the galleries that are open to the public, so being able to work behind the scenes and get a first hand view of the full collection has been incredible.

What is your favorite part about being a scientist, and how did you get interested in science? As a kid, I always loved dinosaurs and fossils. I thought that it was so cool how millions of years ago the world looked completely different, almost alien-like. However, as I grew up, I thought that paleontology wasn’t a “real” career option. So, I went to college thinking I would major in something else. Once I got to college, I had to take a science distribution credit, so I randomly picked an Earth and life history course. There, I realized that being a paleontologist wasn’t so far-fetched of an idea as I had thought. I then took as many geology and paleontology related courses I could, before eventually transferring to the University of Michigan to further pursue paleontology.

What advice do you have for up and coming scientists? Growing up, I never wanted to ask for help or guidance. I was a solitary person who wanted to fix things on their own. However, once I got to college, I realized that asking for help is the best thing you can do. It doesn’t matter how big or small of a question or problem you have, it is never a bad thing to ask for help! A lot of the time, science can be painted as a solitary field where researchers keep to themselves. That is not the way things have to be! Science is done best when people work together. 

How Mushrooms Could Help Clean Up Pollution

Mycoremediation of heavy metals: processes, mechanism and affecting factors

Vinay Kumar and Shiv Kumar Dwivedi

Summarized by Anna Geldert

What data were used? In this review, researchers assessed data from over 300 previous studies on mycoremediation, a process which uses fungi to remove pollutants such as heavy metals from the environment. These studies included findings on the mycoremediation potential of 62 living species of fungi, and 21 dead species. In total, the review considered 11 types of heavy metal pollutants (mercury, cadmium, lead, chromium, copper, arsenic, manganese, nickel, cobalt, zinc and iron) as well as data on drinking water standards, and health impacts of each heavy metal from the World Health Organization (WHO).

Methods: The goal of this review was to synthesize data from existing research, and to identify which factors most affect fungi mycoremediation potential. The authors looked for trends and patterns from previous studies, and summarized findings related to the health impacts of heavy metal exposure to fungal species, as well as the biological, chemical, and physical processes that are used for the absorption of pollutants. They also identified the most important factors affecting the rate of absorption for both living fungi and dead fungal biomass. 

Results: In general, results demonstrate that both heavy metal tolerance and absorption potential differs greatly among species of fungi. Species belonging to the class ascomycete were found to tolerate higher concentrations of heavy metal pollutants, though the explanation for this is still unclear. Both living and dead fungal biomasses were able to absorb heavy metals through a variety of biological processes in the cell wall, and this absorption may be increased further through physical and chemical treatments. In regard to factors that impact absorption rate, the review found that lower pH levels, high agitation (water disturbance) rates, and low flow rates all consistently increased the absorption rate of tested fungi. Factors such as temperature, time, and heavy metal concentration varied based on the species of fungi. Lastly, this study concludes that dead fungal biomass will most likely work better than living fungi for mycoremediation, since varying pH levels, temperatures, and heavy metal concentrations are not limiting factors as dead fungal masses do not need to be kept alive.

A flow chart which starts at a light pink box titled Mycoremediation of heavy metals, which has two main paths, represented by thin black arrows. From this point of origin on the left is a gray box titled By Growing Fungi. This continues to a pink box on the left titled Genetically modified and across from it on the right is a gray box titled Non-Modified. Non-modified continues the chart on its downward path to two more boxes. The left hand box is light pink labeled Indirect Application which below it in parenthese states “By production of siderophores and secondary metabolites”. Across from the light pink box is a gray one with the label Direct Application. Both Direct and Indirect Application continue the chart downward to two light blue boxes with the titles Specific Action of a single fungus and Synergistic Action of more than one fungi, on the left and right respectively. The chart continues from these two, and again are two boxes both in an orange color. They are titled Immobilized form and Free form. Finally this side of the chart ends with two purple boxes labeled Continuous mode and Batch mode. Returning to the beginning of the chart but on the right side, is a blueish gray box titled By Fungal Biomass. This branches into a light blue box on the left titled Activation and across from it, in the same previous blueish gray color is a box labeled Direct Application. From Activation on the left the chart splits into 3 boxes. On the left is a light pink box titled Physical Activation with parentheses stating “heat, magnetic modified, etc”. In the center is a pink box titled Chemical Activation with parentheses stating “acetone, NaOH, ether, etc”. On the right is a light blue box titled Physico-chemical Activation. All 3 boxes continue the chart to a blue box titled Characterization and Application. This light blue box continues to a final box within the chart, and from the left-hand side the chart converges onto this box. This large gray box titled Factors involve in HMS Remediation process. Below it is a list that states Time, pH of the soln, Temperature, Adsorbent conc, Adsorbent dose, Aggitation rate, Medium composition, and Adsorbent type in descending order.
Fig. 1 Flowchart of mycoremediation in wastewater heavy metal treatment methods, comparing the growth of fungi and fungal biomass.

Why is this study important? This study is useful because it draws conclusions from a large body of existing work on mycoremediation, and recognizes important trends in related findings. This allows for comparisons on the mycoremediation potential of various fungal species, treatment methods, and  treatment conditions, which would be much more difficult without a cohesive summary paper such as this one. This study will enable future researchers, and engineers to create novel and efficient methods for treatment of heavy metal wastewater with fungus. 

The big picture: Pollution is one of several environmental challenges facing our planet today, with heavy metal pollutants being one of the most hazardous, due to its negative impacts on human health. Current methods for treating heavy metal contaminants in wastewater are often not economically or environmentally sustainable. Mycoremediation may provide a sustainable solution to this problem, due to fungi’s inherent ability to absorb environmental pollutants, such as heavy metals. This review provides guidance on what fungal species, treatment methods, and treatment conditions would make this remediation process most effective and efficient. 

Citation: Kumar, V., & Dwivedi, S. K. (2021). Mycoremediation of heavy metals: processes, mechanisms, and affecting factors. Environmental Science and Pollution Research, 28(9), 10375–10412.