Small Friends Help Sea Anemones Survive the Heat

Microbiota mediated plasticity promotes thermal adaptation in the sea anemone Nematostella vectensis

Laura Baldassarre, Hua Ying, Adam M. Reitzel, Sören Franzenburg, Sebastian Fraune

Summarized by Blair Stuhlmuller

What data were used? Researchers used cloned Nematostella vectensis, a sea anemone found in estuaries and brackish water environments of the US and UK. N. vectensis hosts many helpful small friends, or symbiotic microbiota. In other words, microscopic organisms that live on the host anemone and help it deal with environmental stressors like temperature changes. These symbionts can be passed onto the offspring from the parent anemone or be acquired from the environment during development. The symbiote assemblage can also change during an anemone’s lifetime in response to changing environmental conditions. The researchers looked at the composition of the microbial communities, the genetics of the host anemone and mortality rates at different temperatures.

Methods: First, in order to control for genetic diversity between individuals, the researchers created clones from a single female polyp (anemone). These individuals were divided into different test groups based on temperature–low (15℃) temperature, medium (20℃)  temperature and high (25℃) temperature–that were studied over the course of three years. Each test group had 5 cultures of 50 cloned anemones.

Results:  After 40 weeks and after 132 weeks, the polyps were exposed to high heat stress (6 hours at 40 ℃) and mortality was measured. In both tests, all of the polyps in the low temperature group died. The high temperature group had the highest survival rate after 132 weeks. Polyps in the high temperature group experienced a lower mortality rate overall, but were also 3 times smaller, and asexually reproduced 7 times more rapidly than those in the low temperature group. These results show that long-term temperature differences have a great impact on heat tolerance, organism size, and reproduction rates.

Next, changes in the microbial symbiont communities were measured through 16S rRNA sequencing (or the process of reading the small section of ribosomal RNA molecules that is in charge of turning the genetic code into actual functioning cell parts) at the 40, 84 and 132 week intervals. The results showed that both the temperature and exposure duration to said temperature had a significant effect on the microbial community composition. Three distinct microbial communities were found for each temperature test group and these communities stabilized within the first two years. 


A bar graph showing the survival rate of each temperature group after experiencing heat stress. After 40 weeks, the survival rate of the group acclimated at 15℃ is 0, the second group, acclimated at 20℃ has a survival rate of 70% and the third group, acclimated at 25℃, has a survival rate of 30%. After 132 weeks, both the 15℃ acclimated group and the 20℃ acclimated group experienced a 0% survival rate. Only the last group, acclimated at 25℃, remained with a survival rate of nearly 100%.
Figure a shows the survival rate of each temperature group (AT is acclimated temperature) to heat stress. Heat stress experiments were conducted at 40 weeks of acclamation (woa) and 132 weeks.

Third, all the active genes (or genes that are making mRNA) were analyzed in order to see if any changes occurred. One polyp from each culture was selected. The polyp’s mRNA was extracted and sequenced or read. Gene expression, or what genes are actively determining an organism’s features and functions, can be influenced by outside factors and can cause changes to an organism’s phenotypes, or physical characteristics, within its lifetime. While the actual DNA sequence is not changed, certain genes can be turned on or off that can then help or hurt the organism. In this study, polyps in the high temperature group experienced a significantly increased expression of genes involved with immunity, metabolism, outer skin cell production and other positive changes. 

Lastly, researchers wanted to determine if the microbial community and thus changes in gene expression were transferable and could increase the heat tolerance of new individuals and future generations of anemones. Thus they transplanted the temperature adapted microbial communities/symbionts to new, non temperature adapted polyps which were cloned from the same female as the experiment population. Then the heat tolerance of the new polyps were tested. Survival rates of the polyps with transplanted microbial communities depended on the source of the transplanted microbial community. Polyps with microbes from the high temperature group had an 80% survival rate, a significantly higher rate compared to the 33% of the polyps with the low temperature microbes. This shows that microbial transplants could prove to be a quick and effective way to help certain organisms cope with environmental changes. 

The researchers also tested if both the gene expression and microbial communities could be naturally transferred from one generation to the next. rRNA sequencing revealed that large parts of the parent microbial community were successfully transplanted to the offspring. The offspring were then subjected to high heat stress. The offspring from the high temperature group showed a significantly higher survival rate compared to the offspring from both the low and medium temperature groups.

Why is this study important? Members of the Cnidarian phylum like corals and sea anemones are under threat due to rapid climate change. Warming water temperatures are causing coral bleaching and other harmful effects. Since coral and many anemones are mostly sessile, or non moving, when mature, they only have two options–adapt or die. And with climate changing so quickly in recent decades, one might expect extinction to be the more likely option for many species. Adaptation is typically limited by random mutations and natural selection, neither of which happens overnight. However, this study shows how adaptation can happen within just one generation. 

Sessile animals that host a range of symbiotic microbiota exposed to high water temperatures can adapt and become more heat stress resistant. Microbes tend to have much faster generation times and can thus evolve more quickly than their hosts. These microbes can then influence the gene expression of their host by turning on or off certain genes further helping the host to survive and adapt during its lifetime. Most excitingly, these changes in gene expression and microbial communities can be passed to the next generation. This study also helps pave the way towards assisted evolution and potentially huge successes in coral conservation. Heat tolerant microbial communities could potentially be selected for in the lab and then transplanted to wild populations. This would allow scientists and conservation groups to improve the fitness of wild populations quickly and effectively help counter the effects of climate change. 

The big picture: Climate change is a looming threat especially for those living in the oceans. As ocean temperatures rise, many marine species will likely migrate towards the poles in order to remain in their desired temperature ranges. However, sessile or mostly non-moving marine organisms like sponges, coral and sea anemones will have a harder time doing that as many are only mobile during their planktonic larvae stages. This study gives a glimpse of hope that these animals will be better able to adapt and survive than previously expected. This study specifically shows that animals exposed to high temperatures, like N. vectensis, can quickly become more heat stress resistant as the symbiotic microbiota shift and adapt. Most importantly these high heat tolerances can be passed to other organisms and future generations. These lab results are mirrored by long term observational studies that show wild populations becoming less heat sensitive than past generations. Overall, this has huge positive conservation implications for coral reefs and other sessile marine communities as climate rapidly changes.

Citation: Baldassarre, L., Ying, H., Reitzel, A.M. et al. Microbiota mediated plasticity promotes thermal adaptation in the sea anemone Nematostella vectensis. Nature Communications 13, 3804 (2022).

How Ancient Ocean Chemistry Might Have Increased Complexity of Life

Ediacaran Reorganization of the Marine Phosphorus Cycle 

Thomas A. Laaksoa, Erik A. Sperling, David T. Johnstona, and Andrew H. Knoll

Summarized by Makayla Palm

What data were used? The purpose of this study was to measure if changes in the phosphorus cycle were linked to changes in the chemical composition of ocean water hundreds of millions of years ago. The phosphorus cycle is the study of the element phosphorus as it travels from deep-sea storage and rock formations into organic life, and back to the seas again. Why study phosphorus in the first place? Phosphorus is essential to life because it is an important component in DNA and RNA structure. Specifically, at the end of the Ediacaran (~625–542 million years ago or mya), there was a jump in complexity in the fossil record (i.e., life became more complex) found in the transition from the Ediacaran to the Cambrian (~542–485 mya); it may be the case that this change in phosphorus can help us understand the changes to life on Earth during this time. Previously collected phosphorite samples (rocks with a high phosphorus content) and newly found samples from the Doushantuo Formation (Ediacaran, China) were used in this study. These phosphorite samples were examined for the following: evaporite volume, strontium isotope ratios, and content of phosphate. Changes in these samples’ ratios and concentrations allow researchers to hypothesize the impacts on water and life during the Ediacaran. Originally, scientists thought the changes may have been due to increased weathering of rocks, but researchers in this study hypothesized that there may have been more to the story. 

Methods: Researchers from this study hypothesized that a change within deeper Ediacaran ocean chemistry may be the cause for the phosphorus cycle change. They tested this hypothesis by using the variables collected (e.g., isotopes) in an equation that measures the possible effects of the phosphorus evaporite remineralizing into phosphorite (typically how phosphorus is stored in the ocean) This equation measures the amount of phosphorus taken out of the storage bank by measuring the fraction of total organic phosphorus that is removed in relation to the amount of phosphorus that reverts back to its original form in the storage bank. 

Results: The changes in ocean chemistry can be found on the atomic scale, where there are electron acceptors (also known as oxidizers) and electron donors (or reducers). The ocean, having been in a state of consistent reducing reactions, may have shifted to have more oxidizers, which would have increased remineralization – specifically, phosphorus remineralization. This remineralization would explain the difference that eventually modified the Ediacaran phosphorus cycle to the modern-day phosphorus cycle. In order for phosphorus to reduce, something needs to accept its electron. In the absence of oxygen (which early Earth was lacking in for billions of years), research indicates sulfate may be a suitable candidate. Samples of sediment did not indicate a change in phosphorus content, so the hypothesis was not supported. This means that the phosphorus was likely staying within the same system and being removed. The phosphorus cycle, similar to the water cycle or carbon cycle, describes the formation, use and recycling of phosphorus from the oceans, to land, and back to the ocean. The data from this study indicate that upwelling, the mixing of nutrients from the bottom of the ocean back to the top, is the reason for increased phosphorus. Upwelling can be caused by deep water currents coming into contact with continents, where cold, nutrient rich water is propelled closer to the surface and warms. The increased upwelling makes sense in the phosphorus cycle because of the extra circulation happening, which would explain the increased presence of phosphorus without an added source of the element. 

This figure represents three different kinds of information collected over the same period of time. The top graph is a bar graph that measures the amount of phosphate evaporite that was removed and not returned to the phosphorus storage bank. The middle bar graph measures the total amount of phosphate resources stored in the form of P2O5. This graph represents the amount in millions of tons. The line graph at the bottom of the figure represents the number of strontium isotopes found within the rock samples. This graph represents inconsistent intervals of small increasing and decreasing values, showing an overall increase through time in each graph. Across all three graphs, columns highlight the appearance of phytoplankton and large animals within the fossil record. The appearance of phytoplankton is approximately 700 million years ago, and the appearance of larger animals is around 720-699 million years ago. The appearance of both is marked by horizontal black bars at the bottom; with each appearance, there is an uptick in strontium 87. More complex life is marked by more phosphate and evaporites. These bars represent the appearance of organisms in all three line graphs.
The figure represents the three different kinds of data discussed in the paper. The top demonstrates the volume ( km cubed) of phosphorite evaporite, with a general trend of increasing evaporite over time.The middle graph represents the amount of phosphate resources stored in the “storage bank” in the ocean (in millions of tons). The bottom graph represents the change in Strontium isotopes, with ebb and flow in value over time, with a general trend that after a strong dip ~ 700 million years, trends upward. Ice ages are indicated with gray vertical bars across all three graphs, indicating a change in ecosystem. The dark horizontal bars at the bottom of the figure indicate when the appearance of phytoplankton and macroscopic animals occur, which is ~ 680 million years for the phytoplankton and ~ 650 million years for the macroscopic animals. The vertical gray shading represents Ice Ages that occurred in the timeline measured on the figure. The figure as a whole points to the correlation of increased phosphorite levels and the first appearance of relatively large animals in the fossil record.

Why is this study important? This study aims to see why the change in phosphorus occurred to better understand the geologic context that precedes a big change in the fossil record. There is a large jump in complexity from Ediacaran to Cambrian organisms, and ocean chemistry (changes in phosphorus levels in this case) may have had something to do with that. The cycling of phosphorus because of upwelling, influenced by continental placement, could have been a driving reason behind these big changes, ecological and evolutionary. 

Big Picture. This study proposes a mechanism for the change in the phosphorus cycle that is observed between the phosphorus cycle today and the phosphorus cycle of the Ediacaran as we know it. Many questions still exist as to how oceans have changed through geologic time and this study provides an important piece to the puzzle. Understanding changes in ocean chemistry, too, better helps scientists understand how life evolves in response. 

Citation: Laakso, Thomas A., et al. “Ediacaran Reorganization of the Marine Phosphorus Cycle.” Proceedings of the National Academy of Sciences, vol. 117, no. 22, 2020, pp. 11961–11967., 

Early childhood and connecting with nature

Effect of environmental education on the knowledge of aquatic ecosystems and reconnection with nature in early childhood

Maria João Feio, Ana Isabel Mantas, Sónia R. Q. Serra, Ana Raquel Calapez, Salomé F. P. Almeida, Manuela C. Sales, Mário Montenegro, Francisca Moreira

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? In 2018, the environmental educational project CresceRio was created in the city of Coimbra, Portugal, to encourage the populace to reconnect with nature, preserve and protect the streams found in the area, and teach children about the importance of the streams and preserving green and blue (terrestrial and aquatic) ecosystems. Most children who live in the city had little exposure to nature and expressed fear and incorrect knowledge about the streams and rivers in their area. It was proposed that introducing field trips to natural areas and hands-on activities to school curriculums would be a low cost yet effective way to improve their relationship with the natural world. 

Methods: Over the course of 14 months, the researchers conducted several surveys with a class of 24 students (aged 5–6 at the beginning of the program). At particular intervals (labeled M), the children were questioned about five main topics: their identification and background, their awareness of streams and rivers, their recognition of the biodiversity that existed in the rivers, their awareness of various factors negatively affecting the rivers, and their awareness of the ecosystem services provided by rivers to the population. 

M1 occurred at the beginning of the program (September 2018) and was followed the next month by a trip to a stream outside of the city that was not seriously affected by urban activity. M2 occurred in November 2018, and the students visited an urban stream that was visibly affected by urban activity including construction, removal of trees, and litter. In February 2019, the students participated in a laboratory class where they examined fallen leaves and were taught to identify various invertebrates and algae using microscopes. M3 took place in March 2019, followed by a workshop in June 2019 where they reviewed photos and videos and discussed what they learned from their previous activities. In October 2019 they visited another urban stream that was slightly less altered than the one they visited before. The last survey was conducted in November 2019 and was done in the form of group interviews. 

Results: The three main takeaways that the researchers identified were 1) that children in urban areas have little contact with or knowledge of nature, 2) after a year of exploring the streams and their ecosystems their knowledge increased (both about the ecosystems and the problems they face) and their fears decreased, and 3) the long duration of the program was key as changes in their attitude and knowledge only became clear after a few activities.

In all five categories explored (personal background and experience, awareness of aquatic ecosystems, recognition of biodiversity, awareness of issues affecting rivers, and awareness of services provided by rivers) the students showed increased interest and cognizance of the streams by the end of the program. Students were more aware of the streams close to where they live as well as the animals (other than fish) that lived there, such as birds and insects. The activities and field trips lessened their fears of imaginary creatures or animals like alligators that did not exist in Portuguese rivers and made them more appreciative of the streams as a resource for water and recreation. They also acknowledged the presence of trees on the banks of the streams that provided oxygen, shelter, and food for animals. The children also showed an increased negativity for litter, lack of trees, too many reeds (that grow unchecked when trees are removed and choke the stream) and too many buildings around the streams. The students were also reported as saying that they would not litter and would discourage others from doing so as well.

The bar graph shows 3 bars for each organism, showing the percentage of students that recognize that organism at the time of the M1, M2, and M3 surveys. Approximate values are: Fauna Fish: M1- 60%, M2- 92%, M3- 87% Invertebrates: M1- 30%, M2- 40%, M3- 75% Insects: M1- 42%, M2- 44%, M3- 33% Dragonflies: M1- 39%, M2- 50%, M3- 68% Butterflies: M1- 30%, M2- 25%, M3- 22% Mosquitoes: M1- 48%, M2- 45%, M3- 38% Shrimps: M1- 60%, M2- 47%, M3- 53% Aquatic snails: M1- 25%, M2- 59%, M3- 30% Mammals: M1- 21%, M2- 19%, M3- 38% Amphibians: M1- 12%, M2- 22%, M3- 25% Birds: M1- 27%, M2- 37%, M3- 30% Aquatic flora Algae: M1- 60%, M2- 82%, M3- 97% Filamentous green algae: M1- 39%, M2- 45%, M3- 79% Aquatic plants: M1- 39%, M2- 63%, M3- 70% Trees Alders: M1- 23%, M2- 18%, M3- 38% Willows: M1- 17%, M2- 27%, M3- 62% Poplars: M1- 10%, M2- 40%, M3-70 % Oaks: M1- 21%, M2- 50%, M3- 70% Ash trees: M1- 17%, M2- 18%, M3- 37%
Figure 1: The percentage of students that can recognize particular flora or fauna over time and as they are more exposed to streams and the organisms that live there.

Why is this study important? Children growing up in urban areas are exposed to various pollutants and obstacles that come from living in the city. Being consistently exposed to nature from an early age can help to combat those negative effects and promote health and wellbeing. Additionally, learning about the importance of aquatic ecosystems naturally inspires children to be interested in conservation and sustainability. This study showed that when given the opportunity to have real experiences in nature, they form their own positive opinions and ideas.

The big picture: Conservation of green and blue ecosystems is dependent on future generations having genuine understanding of and connections to nature. Introducing environmental studies, complete with hands-on activities, to primary education curriculums is an effective way to nurture those connections. Children should be exposed to the natural spaces close to their schools and homes in order to feel connected to nature and have a deeper learning experience.

In the “before” images (a) and (b), the children drew pictures where only a small portion depicts the stream. A few fish are shown, but most of the detail shows the dock, land, buildings and trees, a large portion of sky, and in image (b) lots of people. In the “after” images (c) and (d), the children’s pictures show a large amount of water and a lot of biodiversity, with pictures of insects, snails, and birds.
Figure 2: Pictures drawn by students after their first field trip (a and b) and after their second field trip and laboratory class (c and d)

Citation: Feio MJ, Mantas AI, Serra SRQ, Calapez AR, Almeida SFP, et al. (2022) Effect of environmental education on the knowledge of aquatic ecosystems and reconnection with nature in early childhood. PLOS ONE 17(4): e0266776.

Trees Combat Climate Change in China by Reducing CO2 Levels

Forest management in southern China generates short term extensive carbon sequestration

By: Xiaowei Tong, Martin Brandt, Yuemin Yue, Philippe Ciais, Martin Rudbeck Jepsen, Josep Penuelas, Jean-Pierre Wigneron, Xiangming Xiao, Xiao-Peng Song, Stephanie Horion, Kjeld Rasmussen, Sassan Saatchi, Lei Fan, Kelin Wang, Bing Zhang, Zhengchao Chen, Yuhang Wang, Xiaojun Li and Rasmus Fensholt

Summarized by Anna Geldert

What data were used? Researchers collected data on carbon storage (long-term carbon stocks) and sequestration levels (new uptake of carbon gasses) by forest type. Data was recorded between 2002 and 2017, and the area of study focused on eight provinces in southern China. This data was compared with existing published data on soil moisture levels and national CO2 emissions.

Methods: Researchers used satellite imagery data from MODIS (Moderate Resolution Imaging Spectroradiometer) for the basis of this study. Using approximately 10,000 MODIS images, they divided the area into a grid with a scale of 0.25km2. Using “training points” of known land cover, they trained a computer to estimate the probability of forest cover in each grid cell, as well as the level of change in forest cover over time. Based on this information, grid cells were classified into eight categories of forest types, including dense forest (probability of forest cover ≥ 0.8, with low change), persistent forest (probability ≥ 0.5, with low change), persistent non-forest (probability ≤ 0.5, with low change), recovery (regrowth of deforested areas, causing a gradual shift from non-forest to forest), afforestation (tree plantation in previously unforested areas, causing a rapid shift from non-forest to forests), deforestation (shift from forest to non-forest), rotation (harvested area, causing fluctuation between forest and non-forest) and rotationL (harvested area, causing fluctuations and low forest recovery). Researchers then estimated the carbon density of each forest type using data from a previous study 2015 from GLAS (Geoscience Laser Altimeter System, i.e., a satellite machine designed to measure the vertical structure of forests). MODIS data from this study was cross-referenced with existing passive microwave data from SMOS (soil moisture and ocean salinity), which also measured carbon density from this region, though on a broader scale. SMOS data were also used to determine the average soil moisture in the studied region.

Results: Both tree cover and fossil fuel emissions increased considerably between 2002 and 2017. Using the MODIS data, researchers estimates a carbon sink of 0.11 Pg C year-1 (i.e., petagrams of carbon per year, the equivalent of 0.11 billion metric tons per year) in the region studied. This accounted for roughly 33% of yearly carbon emissions since the year 2012. Unmanaged dense forest had the highest carbon density, accounting for 20.5% of carbon storage despite only occupying 8.8% of the land. However, dense forests had low levels of carbon sequestration, accounting for only 4% of the total uptake. Comparatively, persistent non-forests and managed forests (recovering, afforestation, and rotation areas) all had low levels of carbon storage but accounted for 65% the total carbon sequestration. Persistent forest areas lay somewhere in the middle, with moderate storage and sequestration levels. Heavily harvested forests (deforested and rotationL areas) had much lower sequestration rates, and served as carbon sources rather than sinks. Finally, SMOS data revealed that soil moisture levels tended to be lower in regions with lots of managed forests.

The figure shows a bar graph comparing the type of land to the level of sequestration of CO2 emissions. The x-axis is labeled “Type of land use,” and is numbered 1 through 8. A legend on the right of the graph indicates that each number corresponds to a type of forest or non-forest area: 1 represents dense forest, 2 represents forest, 3 is non-forest, 4 is recovery, 5 is afforestation, 6 is deforestation, 7 is rotation, and 8 in rotationL. A different y-axis is present on either side of the graph, so that both the relative percent of CO2 emissions sequestered and the numerical quantity of carbon sequestered per year are represented. The left axis represents the percentages, and spans from 0 to 7.5, increasing at increments of 1.25. The right axis represents the quantity of carbon sequestered in petagrams per year, spanning from 0.00 to 0.03 and increasing by a factor of 0.05. A separate legend on the bottom of the graph indicates that the dark orange portions of the bars represent the percentage/fraction of carbon sequestered compared to CO2 emissions from China as a whole, while light orange portions correspond to emissions from the eight provinces alone. The land use type with the highest percentage of carbon sequestered was non-forest, which accounted for approximately 6.5% of annual emissions for the eight provinces, or 0.026 total Pg of carbon per year. Non-forest was followed by forest and afforestation (both accounting for 5.2% of emissions and 0.21 total Pg), recovery (4% and 0.016 Pg), rotation (3.5% and 0.013 Pg) and dense forest (1% and 0.009 Pg). Deforestation and rotationL were the only types of land use to represent a negative percentage and quantity of carbon sequestered, indicating that they served as a carbon source rather than a carbon sink. Deforestation accounted for approximately -0.2% (or 0.001 Pg) of carbon sequestration, while rotationL was nearly negligible. The percentages of carbon sequestered when compared to national emissions (dark orange) were all about one fifth of the percentages when compared to the eight provinces alone.
Fig. 1. Average percent of CO2 emissions sequestered annually by each forest type. CO2 emissions from the eight provinces in the study region, as well as emissions from China as a whole, are both shown.

Why is this study important? This study compares the effectiveness of different types of forests in mitigating the impacts of climate change. While natural, dense forests were the best at storing carbon long-term, managed forests were most effective at rapidly removing CO2 from the atmosphere on a shorter timescale. Harvested forests, especially those classified as “rotation,” were especially successful as they were able to sequester relatively high levels of carbon while still providing significant economic revenue from timber for the region. Overall, changes in forest management policies in China in 2002 led to an impressive reduction in carbon emission levels (33%). However, it is important to note that an additional 3 million km2 of forested land would be needed to reach net zero carbon emissions, a number which is unreachable in this region. Likewise, reduced levels of soil moisture indicate that heavily managed forests may not be sustainable in the long run, and will likely be less effective during periods of drought. More research is needed to determine if these forest management policies have already reached maximum effectiveness, or if other adjustments can be made to further increase sequestration.

The big picture: As the main drivers of climate change, fossil fuel emissions continue to threaten our planet. Forestation and forest management policies, such as those established in China at the turn of the century, are a way to mitigate the impact of greenhouse gasses. Modeling future policies after these could help increase carbon sequestration worldwide, especially until renewable energy becomes available. However, as was revealed in this study, it is nearly impossible at current emission levels to reach net zero carbon emissions through forest management alone; in the long term, forest management will likely need to be combined with other policies to ensure a sustainable future.

Citation: Tong, X., Brandt, M., Yue, Y., Ciais, P., Rudbeck Jepsen, M., Penuelas, J., … Fensholt, R. (2020). Forest management in southern China generates short term extensive carbon sequestration. Nature Communications, 11(1).

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.

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).