animals ‣ Data Nuggets

5.16.16

How the cricket lost its song, Part II

In Part I you determined that the Kauai flatwing mutation led to a decrease in parasitism rates for male crickets. Today, most of the male crickets on Kauai have evolved flat wings and can no longer produce songs that were previously used to attract female crickets. Without their songs, how do males attract females?

Robin collecting data on satellite behavior in normal and flatwing mutation males.

The activities are as follows:

Without their song, how are flatwing crickets able to attract females? In some other animal species, like birds, males use an alternative to singing, called satellite behavior. Satellite males hang out near a singing male and attempt to mate with females who have been attracted by the song. This helps satellite males in two ways: they don’t use energy to make a song, and they avoid attracting enemies like the fly. Perhaps the satellite behavior gives flatwing males the opportunity to mate with females who were attracted to the few singing males left on Kauai.

Collecting crickets at the speaker.

To test this idea, Robin set up a speaker playing cricket songs in the fields where the crickets live on Kauai, Oahu, and the Island of Hawaii. The speaker tricks male and female crickets into thinking there is a male cricket in the area making songs. Before the start of the experiment, Robin removed all the males found within a 2-meter circle around the speaker. She then broadcast cricket songs from the speaker for 20 minutes. She returned and counted the number of males in the 2-meter circle, measured the distance from male to the speaker, and noted whether each male was normal or flatwing. Robin expected that flatwing males would be more likely to use satellite behavior and, therefore, would be on average closer to the speaker than normal males.

Featured scientist: Robin Tinghitella from the University of Denver

Flesch–Kincaid Reading Grade Level = 10.0

Additional teacher resources related to this Data Nugget include:

A video introducing the study system and describing how, in fewer than 20 generations, crickets on the island of Kuai went from singing to silent!
Listen to cricket songs!
Several papers have been published on this data and study system:
- Zuk, M., Rotenberry, J.T. & Tinghitella, R.M. 2006. Silent Night: Adaptive disappearance of a sexual signal in a parasitized population of field crickets. Biology Letters 2:521-524.
- Tinghitella, R.M. & Zuk, M. 2009. Asymmetric mating preferences accommodated the rapid evolutionary loss of a sexual signal. Evolution 63:2087-2098.
Some popular science writings on this research:
- UC Berkeley’s Understanding Evolution Website: Quick evolution leads to quiet crickets.
- Science News: Crickets on Mute: Hush falls as killer fly stalks singers. Volume 170 (13).
- A blog post by Robin on her research.

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4.26.16

Make way for mummichogs

Collecting mummichogs and other fish out of research traps.

The activities are as follows:

Salt marshes are important habitats and contain a wide diversity of species. These ecosystems flood with salt water during the ocean’s high tide and drain as the tide goes out. Fresh water also flows into marshes from rivers and streams. Many species in the salt marsh can be affected when the movement of salt and fresh water across a tidal marsh is blocked by human activity, for example by the construction of roads. These restrictions to water movement, or tidal restrictions, can have many negative effects on salt marshes, such as changing the amount of salt in the marsh waters, or blocking fish from accessing different areas.

Local managers are working to remove tidal restrictions and bring back valuable habitat. At the same time, scientists are working to study how the remaining tidal restrictions impact fish populations. To do this, they measure the number of fish found upstream of tidal restrictions, which is the side connected to the river’s freshwater but cut off from the ocean when the restriction is in place. By taking measurements before and after the restriction is removed, scientists can study the impacts that the restriction had on fish populations

Mummichogs are a small species of fish that live in tidal marshes all along the Atlantic coast of the United States.

Mummichogs are a small species of fish that live in tidal marshes all along the Atlantic coast of the United States. They can be found in most streams and marsh areas and are therefore a valuable tool for scientists interested in comparing different marshes. The absence of mummichogs in a salt marsh is likely a sign that it is highly damaged.

In Gloucester, MA, students participating in Mass Audubon’s Salt Marsh Science Project are helping Liz and Robert use mummichogs to examine the health of a salt march. In 2002 and 2003 Liz, Robert, and the students set traps upstream of a road, which was acting as a tidal restriction. These traps collected mummichogs and other species of fish. The day after they set the traps, the students counted the number of each fish species found in the traps.

Students participating in Mass Audubon’s Salt Marsh Science Project Count fish at Eastern Point Wildlife Sanctuary, Gloucester, MA

In December 2003, a channel was dug below the road to remove the tidal restriction and restore the marsh. From 2004 to 2007, students in the program continued to place traps in the same upstream location and collect data in the same way each year. Students then compared the number of fish from before the restoration to the numbers found after the restriction was removed. The students thought that once the tidal restriction was removed, mummichogs would return to the upstream locations in the marsh.

Featured scientists: Liz Duff and Robert Buchsbaum from Mass Audubon. Written by: Maria Maradianos, Samantha Scola, and Megan Wagner.

Flesch–Kincaid Reading Grade Level = 10.9

Additional teacher resources related to this Data Nugget:

Data is available at Mass Audubon’s Salt Marsh Science websites on the Salt Marsh Science Project and their Fish Results & Data.
This activity has been aligned to the NGSS and is listed on the NSTA website.
To view images from the restoration, marsh, and data collection, check out our PowerPoint presentation to accompany this Data Nugget.
This research was funded by the National Science Foundation as part of the Plum Island Ecosystems Long Term Ecological Research site.

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4.20.16

The birds of Hubbard Brook, Part II

In Part I, you examined patterns of total bird abundance at Hubbard Brook Experimental Forest. These data showed bird numbers at Hubbard Brook have declined since 1969. Is this true for every species of bird? You will now examine data for four species of birds to see if each of these species follows the same trend.

Red-eyed vireo in the Hubbard Brook Experimental Forest

The activities are as follows:

It is very hard to study migratory birds because they are at Hubbard Brook only during their breeding season (summer in the Northern Hemisphere). They spend the rest of their time in the southeastern United States, the Caribbean or South America or migrating between their two homes. Therefore, it can be difficult to tease out the many variables affecting bird populations over their entire range. To start, scientists decided to focus on what they could study—the habitat types at Hubbard Brook and how they might affect bird populations.

Hubbard Brook Forest was heavily logged and disturbed in the early 1900s. Trees were cut down to make wood products, like paper and housing materials. Logging ended in 1915, and various plants began to grow back. The area went through what is called secondary succession, which refers to the naturally occurring changes in forest structure that happen as a forest recovers after it was cut down or otherwise disturbed. Today, the forest has grown back. Scientists know that as the forest grew older, its structure changed: Trees grew taller, the types of trees changed, and there was less shrubby understory. The forest now contains a mixture of deciduous trees that lose their leaves in the winter (about 80–90%; mostly beech, maples, and birches) and evergreen trees, mostly conifers, that stay green all year (about 10–20%; mostly hemlock, spruce, and fir).

Richard and his fellow scientists already knew a lot about the birds that live in the forest. For example, some bird species prefer habitats found in younger forests, while others prefer habitats found in older forests. They decided to look carefully into the habitat preferences of four important species of birds—Least Flycatcher, Red-eyed Vireo, Black-throated Green Warbler, and American Redstart—and compare them to habitats available at each stage of succession. They wondered if habitat preference of a bird species is associated with any change in the bird populations at Hubbard Brook since the beginning of succession.

Least Flycatcher: The Least Flycatcher prefers to live in semi-open, mid-successional forests. The term mid-successional refers to forests that are still growing back after a disturbance. These forests usually consist of trees that are all about the same age and have a thick canopy at the top with few gaps, a relatively open area under the canopy, and a denser shrub layer close to the ground.
Black-throated Green Warbler: The Black-throated Green Warbler occupies a wide variety of habitats. It seems to prefer areas where deciduous and coniferous forests meet and can be found in both forest types. It avoids disturbed areas and forests that are just beginning succession. This species prefers both mid-successional and mature forests.
Red-eyed Vireo: The Red-eyed Vireo breeds in deciduous forests as well as forests that are mixed with deciduous and coniferous trees. They are abundant deep in the center of a forest. They avoid areas where trees have been cut or blown down and do not live near the edge. After an area is logged, it often takes a very long time for this species to return.
American Redstart: The American Redstart generally prefers moist, deciduous, forests with many shrubs. Like the Least Flycatcher, this species prefers mid-successional forests.

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle and Jackie Wilson.

Flesch–Kincaid Reading Grade Level = 10.6

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

There is an engaging video that can be used before the students begin the activity. It introduces some of the researchers behind this body of work, including Richard Holmes, and highlights the importance of the long-term nature of this dataset.
For the full dataset associated with this Data Nugget, check out the Hubbard Brook Data Catalog page. Search for “Bird abundances” in the search bar to find the dataset.
For more information on this research, check out the Hubbard Brook Experimental Forest’s page on their songbird research
For more lessons created from data collected on birds at Hubbard Brook, check out the page “Migratory Birds Math and Science Lessons from Hubbard Brook.”

There are multiple publications related to the data included in this activity:

Holmes, R. T. 2011. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021.
Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13.
Townsend, A. K., et al. (2016). The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird. Global Change Biology 2: 544-555.

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4.20.16

The birds of Hubbard Brook, Part I

Male Black-throated Blue Warbler feeding nestlings. Nests of this species are built typically less than one meter above ground in a shrub such as hobblebush. Photo by N. Rodenhouse.

The activities are as follows:

The Hubbard Brook Experimental Forest is an area where scientists have collected ecological data for many years. It is located in the White Mountains of New Hampshire. Data collected in this forest helps uncover environmental trends over long periods of time, such as changes in air temperature, precipitation, forest growth, and animal populations. It is important to collect data on ecosystems over time because these patterns could be missed with shorter observation periods or short-term experiments.

Richard Holmes is an avian ecologist who began this study because he was interested in how bird populations were responding to long-term environmental change.

Each spring, Hubbard Brook comes alive with the arrival of migratory birds. Many come from the tropics to take advantage of abundant insects and the long summer days of northern areas. In the spring, avian ecologists, or scientists who study the ecology of birds, also become active in the forest at Hubbard Brook. They have been keeping records on the birds that live in the experimental forest for over 50 years. These data are important because they represent one of the longest bird studies ever conducted!

Richard is an avian ecologist who began this study early in his career as a scientist. He was interested in how bird populations respond to long-term environmental changes at Hubbard Brook. Every summer since 1969, Richard takes his team of trained scientists, students, and technicians into the field to identify which species are present. Richard’s team monitors populations of over 30 different bird species. They count the number of birds that are in the forest each year and study their activities during the breeding season. The researchers wake up every morning before the sun rises and travel to the far reaches of the forest. They listen for, look for, identify, and count all the birds they find. The team has been trained to be able to identify the birds by sight, but also by their calls. Team members are even able to identify how far away a bird is by hearing its call!

The study area is located away from any roads or other disturbed areas. To measure the abundance, or number of birds found in the 10 hectare study area, the researchers used what is called the spot-mapping method. They use plastic flags on trees 50 meters apart throughout the study area to create a 50×50 meter grid. The grid allows them to map where birds are found in this area, and when possible, where they locate their nests. Using the grid the researchers systematically walk through the plot several days each week from early May until July, recording the presence and activities of every bird they find. They also note the locations of nearby birds singing at the same time. These records are combined on a map to figure out a bird’s territory, or activity center. At the end of the breeding season they count up the number of territories to get an estimate of the number of birds on the study area. This information, when paired with observations on the presence and activities of mates, locations of nests, and other evidence of breeding activity provide an accurate estimate for bird abundance. Finally, some species under close study, like American Redstart and Black-throated Blue Warbler, were captured and given unique combinations of colored bands, which makes it easier to track individuals.

By looking at bird abundance data across many years, Richard and his colleagues can identify trends that reveal how avian populations change over time.

Featured scientist: Richard Holmes from the Hubbard Brook Experimental Forest. Data Nugget written by: Sarah Turtle and Jackie Wilson.

Flesch–Kincaid Reading Grade Level = 11.3

A view of the Hubbard Brook Experimental Forest

Additional teacher resource related to this Data Nugget:

There is an engaging video that can be used before the students begin the activity. It introduces some of the researchers behind this body of work, including Richard Holmes, and highlights the importance of the long-term nature of this dataset.
For the full dataset associated with this Data Nugget, check out the Hubbard Brook Data Catalog page. Search for “Bird abundances” in the search bar to find the dataset.
For more information on this research, check out the Hubbard Brook Experimental Forest’s page on their songbird research
For more lessons created from data collected on birds at Hubbard Brook, check out the page “Migratory Birds Math and Science Lessons from Hubbard Brook.”

There are multiple publications related to the data included in this activity:

Holmes, R. T. 2011. Birds in northern hardwoods ecosystems: Long-term research on population and community processes in the Hubbard Brook Experimental Forest. Forest Ecology and Management doi:10.1016/j.foreco.2010.06.021.
Holmes, R.T., 2007. Understanding population change in migratory songbirds: long-term and experimental studies of Neotropical migrants in breeding and wintering areas. Ibis 149 (Suppl. 2), 2-13.
Townsend, A. K., et al. (2016). The interacting effects of food, spring temperature, and global climate cycles on population dynamics of a migratory songbird. Global Change Biology 2: 544-555.

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3.18.16

Does sea level rise harm Saltmarsh Sparrows?

Painting of the saltmarsh sparrow

The activities are as follows:

For the last 100 years, sea levels around the globe have increased dramatically. The cause of sea level rise has been investigated and debated. Data from around the world supports the hypothesis that increasing sea levels are a result of climate change caused by the burning of fossil fuels. As we warm the Earth, the oceans get warmer and polar ice caps melt. The dramatic increase in sea level that results could seriously threaten ecosystems and the land that humans have developed along the coast.

Salt marshes are plains of grass that grow along the east coast of the United States and many coasts worldwide. Salt marshes grow right at sea level and are therefore very sensitive to sea level rise. In Boston Harbor, Massachusetts, the NOAA (National Oceanic and Atmospheric Administration) Tide Gauge has measured a 21mm rise in sea level over the last 8 years. That means every year sea level has gone up an average of 2.6mm since 2008 – more than two and a half times faster than before we started burning fossil fuels! Because sea level is going up at such a fast rate, Robert, a scientist in Boston, became concerned for the local salt marsh habitats near his home. Robert was curious about what will happen to species that depend on Boston’s Plum Island Sound salt marshes when sea levels continue to rise.

Robert preparing his team for a morning of salt marsh bird surveys.

Robert decided to look at species that are very sensitive to changes in the salt marsh. When these sensitive species are present, they indicate the marsh is healthy. When these species are no longer found in the salt marsh, there might be something wrong. The Saltmarsh Sparrow is one of the few bird species that builds its nests in the salt marsh, and is totally dependent on this habitat. Saltmarsh Sparrows rely completely on salt marshes for feeding and nesting, and therefore their numbers are expected to decline as sea levels rise and they lose nesting sites. Robert heard that scientists studying Connecticut marshes reported the nests of these sparrows have been flooded in recent years. He wanted to know if the sparrows in Massachusetts were also losing their nests because of high sea levels.

For the past two decades Robert has kept track of salt marsh breeding birds at Plum Island Sound. In his surveys since 2006, Robert counted the number of Saltmarsh Sparrows in a given area. He did these surveys in June when birds are most likely to be breeding. He used the “point count” method – standing at a center point he measured out a 100 meter circle around him. Then, for 10 minutes, he counted how many and what kinds of birds he saw or heard within and just outside the circle. Each year he set up six count circles and performed counts three times in June each year at each circle. Robert also used sea level data from Boston Harbor that he can relate to the data from his bird surveys. He predicted that sea levels would be rising in Plum Island Sound and Saltmarsh Sparrow populations would be falling over time.

Featured scientist: Robert Buchsbaum from Mass Audubon. Written by: Wendy Castagna, Daniel Gesin, Mike McCarthy, and Laura Johnson

Flesch–Kincaid Reading Grade Level = 9.5

Additional teacher resources related to this Data Nugget include:

A PDF of the 2014 overview report on the Saltmarsh Habitat and Avian Research Program (SHARP) for the east coast marshes from Maine down to Maryland, which includes Massachusetts. The report may be helpful for students as they come up with other research questions.
A blog by SHARP, covering a wide diversity of salt marsh research!
Data from the Plum Island Sound LTER project.
Data from NOAA tide gauges in Boston Harbor. This dataset expands on that found in Table 1. Students can explore long-term data for Boston Harbor, or can explore other areas for independent research.
For more Boston Harbor tide information, or to look up tides in their area, students can also explore Tideschart.

3.11.16

CSI: Crime Solving Insects

Scientist Paula catching blow flies in the field using an insect net.

Scientist Parker catching blow flies in the field using an insect net.

The activities are as follows:

Most people think that maggots are gross, but they are important decomposers in many ecosystems. Without maggots and other decomposers, we would all trip over the bodies of dead organisms every time we went outside! Not only do maggots break down dead animal bodies in nature, but they also decompose human bodies!

Forensic entomology is a science that uses these amazing insects to help the criminal justice system. Maggots are the larvae of blow flies. Remember the next time you swat away a fly, these little insects help police solve crimes! Adult blow flies are usually the first to arrive at a crime scene with a dead body. The blow flies lay their eggs, or oviposit, shortly after their arrival. These eggs hatch and become maggots that feed on the body. Scientists can use the age of the maggot to help estimate how long someone has been dead. The longer a body has been dead, the longer ago the eggs hatched and the older the maggot larvae will be.

Kristi and Parker, two forensic entomologists, were in the field one day, documenting the timing of blow fly oviposition. They noticed something unexpected! There were wasps stuck in the traps they were using to catch blow flies. The scientists wondered if these wasps can affect a blow fly’s decision to oviposit because wasps attack adult blow flies and also eat their eggs. Kristi and Parker knew that blow flies have an incredible sense of smell and sight. They wondered if blow flies are able to use their senses to detect if a wasp is near a body and then choose to avoid the area or delay laying their eggs. The scientists predicted that blow flies should delay their oviposition when wasps were present near a body. If wasps indeed cause blow flies to delay oviposition, this could change how scientist’s use maggot age to determine how long ago a body died.

Control bait cup with a large number of blow flies on the chicken liver

To test their hypothesis, the scientists did 10 trials in the field. They used bait cups that contained chicken liver to simulate a dead human body. A total of 9 bait cups were used in each of the 10 trials, for a total of 90 cups. Of the 9 cups used in each trial, three contained only chicken liver, to represent a body with no wasps present. These cups were used as controls. Three cups contained chicken liver and a wasp pinned to the side of the bait cup so that there was a visual cue of the wasp. The final three cups had a crushed wasp sprinkled over chicken liver to see if blow flies could use a smell cue to tell that a wasp was present without seeing them. Kristi and Parker checked the cups every half hour for the presence of blow fly eggs. If they saw any eggs, they recorded the time of oviposition in hours after sunrise. They then brought the maggots to the lab and raised them to the third larval stage and identified them to species.

Featured scientists: Kristi Bugajski and Parker Stoller from Valparaiso University

Flesch–Kincaid Reading Grade Level = 7.6

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12.21.15

The Flight of the Stalk-Eyed Fly

Variation between stalk-eyed fly species in eyestalk length.

The activities are as follows:

Stalk-eyed flies are insects with eyes located on the ends of long projections on the sides of their head, called eyestalks. Male stalk-eyed flies have longer eyestalks than females, and this plays an important role in the flies’ mating patterns. Female stalk-eyed flies prefer to mate with males with longer eyestalks. In this way, the eyestalks are much like the bright and colorful peacock’s tail. This kind of sexual selection can lead to the evolution of longer and longer eyestalks over generations. But do these long eyestalks come at a cost? For example, longer eyestalks could make it more difficult to turn quickly when flying. As with all flies, stalk-eyed flies do not fly in a straight line all the time, and often zigzag in air. If long eyestalks make quick turns more difficult, we might expect there to be a trade-off between attracting mates and flight.

Moment of inertia (I) is defined as an object’s tendency to resist rotation – in other words how difficult it is to make something turn. An object is more difficult to turn (has a higher moment of inertia) when it is more massive, and when it is further from its axis of rotation. Imagine trying to swing around quickly holding a gallon of water – this is difficult because the water has a lot of mass. Now imagine trying to swing around holding a baseball bat with a jug of water attached to the end. This will be even more difficult, because the mass is further away from the axis of rotation (your body). Now lets bring that back to the stalk-eyed fly. The baseball bat now represents the eyestalk of the fly, while the gallon of water represents the eye at the end of the stalk. We can express the relationship between the mass of the object (m = mass of the eye), its distance from the axis of rotation (R = length of eyestalk), and the moment of inertia (I) using the following equation: I = mR².

Because moment of inertia goes up with the square of the distance from the axis, we might expect that as the length of the flies’ eyestalks goes up, the harder and harder it will be for the fly to maneuver during flight. If this is the case, we would predict that male stalk-eyed flies would make slower turns compared to similar sized female flies with shorter eyestalks.

Differences in male and female eyestalk length.

To address this idea, scientists measured the effect of eyestalk length on the moment of inertia of the body needs. In addition, they measured differences in turning performance during flight. Scientists Gal and John tracked free flight trajectories of female and male stalk-eyed flies in a large flight chamber. Because female and male stalk-eyed flies have large differences in eyestalk length, their flight performance can be compared to determine the effects of eyestalk length on flight. However, other traits may differ between males and females, so body size and wing length measurements were also taken. If increased moment of inertia does limit turning performance as expected, the male flies that have significantly longer eyestalks should demonstrate slower and less tight turns, indicating a decrease in free flight performance. If there is no difference in turning performance between males and females with significantly different eyestalk lengths, then males must have a way to compensate for the higher moment of inertia.

Featured scientists: Gal Ribak from Tel-Aviv University, Israel and John Swallow from University of Colorado, Denver. Written by: Brooke Ravanelli from Denver Public School, Zoё Buck Bracey from BSCS, and John Swallow.

Flesch–Kincaid Reading Grade Level = 9.0

Once your students have completed this Data Nugget, there is an extension lab activity where students can conduct their own experiment testing moment of inertia. Students simulate the flying experience of stalk-eyed flies and go through an obstacle course carrying their eyestalks with them as they maneuver through the cones to the finish line. To access this lab, click here!

Video showing how the long eyestalks of males form!

11.5.15

Data Nugget Workshop at NABT 2015: A Tail of Two Scorpions

You can get the slides from our NABT talk here: A Tail of Two Scorpions

11.3.15

Lizards, iguanas, and snakes! Oh my!

The Common Side-blotched Lizard

The activities are as follows:

Throughout history people have settled mainly along rivers and streams. Easy access to water provides resources to support many people living in one area. In the United States today, people have settled along 70% of rivers.

Today, rivers are very different from what they were like before people settled near them. The land surrounding these rivers, called riparian habitats, has been transformed into land for farming, businesses, or housing for people. This urbanization has caused the loss of green spaces that provide valuable services, such as water filtration, species diversity, and a connection to nature for people living in cities. Today, people are trying to restore green spaces along the river to bring back these services. Restoration of disturbed riparian habitats will hopefully bring back native species and all the other benefits these habitats provide.

Scientist Mélanie searching for reptiles in the Central Arizona-Phoenix LTER.

Scientists Heather and Mélanie are researchers with the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) project. They want to know how restoration will affect animals living near rivers. They are particularly interested in reptiles, such as lizards. Reptiles play important roles in riparian habitats. Reptiles help energy flow and nutrient cycling. This means that if reptiles live in restored riparian habitats, they could increase the long-term health of those habitats. Reptiles can also offer clues about the condition of an ecosystem. Areas where reptiles are found are usually in better condition than areas where reptiles do not live.

Heather and Mélanie wanted to look at how disturbances in riparian habitats affected reptiles. They wanted to know if reptile abundance (number of individuals) and diversity (number of species) would be different in areas that were more developed. Some reptile species may be sensitive to urbanization, but if these habitats are restored their diversity and abundance might increase or return to pre-urbanization levels. The scientists collected data along the Salt River in Arizona. They had three sites: 1) a non-urban site, 2) an urban disturbed site, and 3) an urban rehabilitated site. They counted reptiles that they saw during a survey. At each site, they searched 21 plots that were 10 meters wide and 20 meters long. The sites were located along 7 transects, or paths measured out to collect data. Transects were laid out along the riparian habitat of the stream and there were 3 plots per transect. Each plot was surveyed 5 times. They searched for animals on the ground, under rocks, and in trees and shrubs.

Featured scientists: Heather Bateman and Mélanie Banville from Arizona State University. Written by Monica Elser from Arizona State University.

Flesch–Kincaid Reading Grade Level = 9.8

Check out this video of Heather and her lab out in the field collecting lizards:

Virtual field trip to the Salt River biodiversity project:

Additional resources related to this Data Nugget:

For more background on the importance of biodiversity, students can eat this article in The Guardian – What is biodiversity and why does it matter to us?

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10.19.15

Green crabs: invaders in the Great Marsh

Scientist Alyssa holding a non-native green crab, introduced from Europe to the American Atlantic Coast. This crab causes many problems in its new range, including the loss of native eelgrass.

The activities are as follows:

Marshes, areas along the coast that flood with each tide, are incredibly important habitats. They act as homes to large number of species, protect the coast from erosion during storms, and act as a filter for nutrients and pollution. Many species are unique to these habitats and provide crucial support to the marsh. For example, native eelgrass, a type of plant, minimizes erosion by holding sediments in place with their roots.

In an effort to help protect and restore marshes, we must understand current-day issues that are affecting their health. The introduction of non-native species, species that are not originally from this ecosystem, into a marsh may disrupt the marsh ecosystem and threaten the survival of native species. One species that has recently caused a lot of trouble is the European green crab. This crab species was accidentally carried to the Atlantic coast back in the early 1800s from Europe. Since then, they have become extremely invasive and their numbers have exploded! Compared to native crabs, the green crab digs a lot when it searches for food and shelter. This digging uproots eelgrass and causes its population numbers to fall. In many spots where green crabs have been introduced, marshes are now bare and no more grass can grow.

Non-native green crabs caught in trap that has been underwater for 25 hours

The Great Marsh is one of the coastal habitats affected by invasive green crabs. Located on the North Shore of Massachusetts, the Great Marsh is known for being the longest continuous stretch of salt marsh in all of New England. Alyssa is a restoration ecologist who is very concerned with the conservation of the Great Marsh and other important coastal ecosystems. She and other scientists are trying to maintain native species while also reducing the effects of non-native species.

A major goal for Alyssa is to restore populations of a native eelgrass. Eelgrass does more than just prevent erosion. It also improves water quality, provides food and habitat for native animal species, and acts as an indicator of marsh health. If green crabs are responsible for the loss of eelgrass from the marsh, then restorations where eelgrass is planted back into the marsh should be more successful where green crab numbers are low. Alyssa has been measuring green crab populations in different areas by laying out green crab traps for 24 hours. Alyssa has set these traps around Essex Bay, an area within the Great Marsh. She recorded the total number of green crabs caught at each location (as well as their body size and sex).

Native eelgrass growing in Essex Bay, an area within the Great Marsh

Featured scientist: Alyssa Novak, Center for Coastal Studies/Boston University. Written by: Hanna Morgensen

Flesch–Kincaid Reading Grade Level = 8.8