Biomedical Bleeding of Horseshoe Crabs for Pharmaceuticals Puts Species at Risk
By Rebecca Zeiber
New research from Plymouth State University (PSU) and the University of New Hampshire (UNH) indicates that collecting and bleeding horseshoe crabs for biomedical purposes causes short-term changes in their behavior and physiology that could exacerbate the crabs’ population decline in parts of the east coast.
Each year, the U.S. biomedical industry harvests the blue blood from almost half a million living horseshoe crabs for use in pharmaceuticals—most notably, a product called Limulus amebocyte lysate (LAL), used to ensure vaccines and medical equipment are free of bacterial contamination. This lifesaving product can only be made from horseshoe crab blood, says researcher Win Watson, UNH professor of zoology.
“The crabs are very heavily bled—about 30 percent or more of their blood is taken, and that’s a fair amount,” said Chris Chabot, professor of neurobiology at PSU and a co-author on the study. “Approximately 20 to 30 percent of those crabs do not survive, so we were curious if any of the surviving crabs experienced nearly lethal effects from the bleeding.”
The study, Sublethal Behavioral and Physiological Effects of the Biomedical Bleeding Process on the American Horseshoe Crab, was published recently in the journal The Biological Bulletin.
With funding provided by a N.H. Sea Grant development grant, Chabot, Watson and lead author Rebecca Anderson, a PSU graduate student, replicated the biomedical bleeding process to determine the potential impacts on the crabs’ behavior.
After capturing the crabs in New Hampshire’s Great Bay and transporting some of them back to Chabot’s lab at PSU and others to UNH’s Jackson Estuarine Laboratory, the researchers monitored their movements for a week and then harvested some of their blood. Electronic data recorders called accelerometers that measure the crabs’ speed and direction were strapped to their backs and the crabs were placed in running wheels in tanks filled with seawater.
The researchers found that for approximately two weeks after the bleeding procedure, the crabs’ behavior differed from their behavior prior to the bleeding—they moved less frequently and with different patterns and rhythms, indicating they may have been disoriented. The researchers hope to track the movements of bled horseshoe crabs in their native environments to verify that their lab findings apply to real life behavioral changes.
One of the concerns, Anderson explains, is that the crabs are collected for bleeding during their breeding cycle when it’s easiest to capture them on beaches. If the crabs are bled and then returned to the beach in a disoriented condition, they might be less likely to breed. This has the potential to exacerbate the population declines that are already occurring in parts of the east coast, including Delaware and Cape Cod. The populations in New Hampshire seem to be holding steady at the moment.
“If the biomedical industry could delay the blood harvest, it would probably help these animals,” Chabot said. “For example, if they are bled after the breeding season, then they could recover in the subsequent months, fatten up and survive the winter without any problems to be able to breed again the following year.”
Watson suggests that the conditions under which they are transported could be improved as well. Fishermen capture the horseshoe crabs and often place them on a hot boat deck until they are transported by truck to the biomedical facility, all the while out of water and unable to breathe. If instead they were kept in cold, well-aerated water and perhaps fed, their stress levels might decrease and thus improve their chances of survival and ability to breed upon return to their native habitat.
Watson also notes that it is unclear which part of the process is the most detrimental—the bleeding, the transporting or simply keeping the crabs in the lab and out of their natural environment. Their research also revealed that the crabs’ levels of hemocyanin, a protein in their system that helps transport oxygen in their blood, decreased for all individuals regardless of whether or not they were bled. Lowered hemocyanin levels might lessen the crabs’ resilience to the stress of the experience.
Regardless, the researchers feel improvements in the collection and bleeding process are imperative to help preserve the species. In addition to the economic value of their blood, horseshoe crab eggs provide a critical food source for shorebirds that stop in Delaware on their migration to the Arctic. The adult crabs are also harvested for bait in the whelk and eel fisheries in many states, not including New Hampshire.
“We want to ensure that the biomedical bleeding is a sustainable practice, because horseshoe crabs are a critical component of the coastal ecosystem,” Chabot said.
"I hope that this research helps to design management regulations that meet the needs of both the people and the crabs,” Anderson adds.
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By Bob Jacobs
Hanako, a female Asian elephant, lived in a tiny concrete enclosure at Japan's Inokashira Park Zoo for more than 60 years, often in chains, with no stimulation. In the wild, elephants live in herds, with close family ties. Hanako was solitary for the last decade of her life.
Hanako, an Asian elephant kept at Japan's Inokashira Park Zoo; and Kiska, an orca that lives at Marineland Canada. One image depicts Kiska's damaged teeth. Elephants in Japan (left image), Ontario Captive Animal Watch (right image), CC BY-ND
Affecting Health and Altering Behavior<p>It is easy to observe the overall health and psychological consequences of life in captivity for these animals. Many captive elephants suffer from arthritis, obesity or skin problems. Both <a href="https://doi.org/10.11609/JoTT.o2620.1826-36" target="_blank">elephants</a> and orcas often have severe dental problems. Captive orcas are plagued by <a href="https://doi.org/10.1016/j.jveb.2019.05.005" target="_blank">pneumonia, kidney disease, gastrointestinal illnesses and infections</a>.</p><p>Many animals <a href="https://doi.org/10.1016/j.neubiorev.2017.09.010" target="_blank">try to cope</a> with captivity by adopting abnormal behaviors. Some develop "<a href="https://doi.org/10.1016/j.applanim.2017.05.003" target="_blank" rel="noopener noreferrer">stereotypies</a>," which are repetitive, purposeless habits such as constantly bobbing their heads, swaying incessantly or chewing on the bars of their cages. Others, especially big cats, pace their enclosures. Elephants rub or break their tusks.</p>
Changing Brain Structure<p>Neuroscientific research indicates that living in an impoverished, stressful captive environment <a href="https://doi.org/10.1016/j.jveb.2019.05.005" target="_blank" rel="noopener noreferrer">physically damages the brain</a>. These changes have been documented in many <a href="https://doi.org/10.1002/cne.903270108" target="_blank" rel="noopener noreferrer">species</a>, including rodents, rabbits, cats and <a href="https://doi.org/10.1006/nimg.2001.0917" target="_blank" rel="noopener noreferrer">humans</a>.</p><p>Although researchers have directly studied some animal brains, most of what we know comes from observing animal behavior, analyzing stress hormone levels in the blood and applying knowledge gained from a half-century of neuroscience research. Laboratory research also suggests that mammals in a zoo or aquarium have compromised brain function.</p>
This illustration shows differences in the brain's cerebral cortex in animals held in impoverished (captive) and enriched (natural) environments. Impoverishment results in thinning of the cortex, a decreased blood supply, less support for neurons and decreased connectivity among neurons. Arnold B. Scheibel, CC BY-ND<p>Subsisting in confined, barren quarters that lack intellectual stimulation or appropriate social contact seems to <a href="https://doi.org/10.1590/S0001-37652001000200006" target="_blank" rel="noopener noreferrer">thin the cerebral cortex</a> – the part of the brain involved in voluntary movement and higher cognitive function, including memory, planning and decision-making.</p><p>There are other consequences. Capillaries shrink, depriving the brain of the oxygen-rich blood it needs to survive. Neurons become smaller, and their dendrites – the branches that form connections with other neurons – become less complex, impairing communication within the brain. As a result, the cortical neurons in captive animals <a href="https://doi.org/10.1002/cne.901230110" target="_blank">process information less efficiently</a> than those living in <a href="https://doi.org/10.1002/dev.420020208" target="_blank">enriched, more natural environments</a>.</p>
An actual cortical neuron in a wild African elephant living in its natural habitat compared with a hypothesized cortical neuron from a captive elephant. Bob Jacobs, CC BY-ND<p>Brain health is also affected by living in small quarters that <a href="https://doi.org/10.3233/BPL-160040" target="_blank">don't allow for needed exercise</a>. Physical activity increases the flow of blood to the brain, which requires large amounts of oxygen. Exercise increases the production of new connections and <a href="http://dx.doi.org/10.1126/science.aaw2622" target="_blank">enhances cognitive abilities</a>.</p><p>In their native habits these animals must move to survive, covering great distances to forage or find a mate. Elephants typically travel anywhere from <a href="https://www.elephantsforafrica.org/elephant-facts/#:%7E:text=How%20far%20do%20elephants%20walk,km%20on%20a%20daily%20basis." target="_blank">15 to 120 miles per day</a>. In a zoo, they average <a href="https://doi.org/10.1371/journal.pone.0150331" target="_blank" rel="noopener noreferrer">three miles daily</a>, often walking back and forth in small enclosures. One free orca studied in Canada swam <a href="https://doi.org/10.1007/s00300-010-0958-x" target="_blank" rel="noopener noreferrer">up to 156 miles a day</a>; meanwhile, an average orca tank is about 10,000 times smaller than its <a href="https://www.cascadiaresearch.org/projects/killer-whales/using-dtags-study-acoustics-and-behavior-southern" target="_blank" rel="noopener noreferrer">natural home range</a>.</p>
Disrupting Brain Chemistry and Killing Cells<p>Living in enclosures that restrict or prevent normal behavior creates chronic frustration and boredom. In the wild, an animal's stress-response system helps it escape from danger. But captivity traps animals with <a href="https://doi.org/10.1073/pnas.1215502109" target="_blank">almost no control</a> over their environment.</p><p>These situations foster <a href="https://doi.org/10.1037/rev0000033" target="_blank">learned helplessness</a>, negatively impacting the <a href="https://doi.org/10.1155/2016/6391686" target="_blank" rel="noopener noreferrer">hippocampus</a>, which handles memory functions, and the <a href="https://doi.org/10.1016/j.neuropharm.2011.02.024" target="_blank" rel="noopener noreferrer">amygdala</a>, which processes emotions. Prolonged stress <a href="https://doi.org/10.3109/10253899609001092" target="_blank" rel="noopener noreferrer">elevates stress hormones</a> and <a href="https://doi.org/10.1523/JNEUROSCI.10-09-02897.1990" target="_blank" rel="noopener noreferrer">damages or even kills neurons</a> in both brain regions. It also disrupts the <a href="https://doi.org/10.1016/j.neubiorev.2005.03.021" target="_blank" rel="noopener noreferrer">delicate balance of serotonin</a>, a neurotransmitter that stabilizes mood, among other functions.</p><p>In humans, <a href="https://doi.org/10.1006/nimg.2001.0917" target="_blank" rel="noopener noreferrer">deprivation</a> can trigger <a href="https://doi.org/10.3389/fnins.2018.00367" target="_blank" rel="noopener noreferrer">psychiatric issues</a>, including depression, anxiety, <a href="https://doi.org/10.3389/fnins.2018.00367" target="_blank" rel="noopener noreferrer">mood disorders</a> or <a href="https://doi.org/10.1177/1073858409333072" target="_blank" rel="noopener noreferrer">post-traumatic stress disorder</a>. <a href="https://doi.org/10.1007/s00429-010-0288-3" target="_blank" rel="noopener noreferrer">Elephants</a>, <a href="https://doi.org/10.1371/journal.pbio.0050139" target="_blank" rel="noopener noreferrer">orcas</a> and other animals with large brains are likely to react in similar ways to life in a severely stressful environment.</p>
Damaged Wiring<p>Captivity can damage the brain's complex circuitry, including the basal ganglia. This group of neurons communicates with the cerebral cortex along two networks: a direct pathway that enhances movement and behavior, and an indirect pathway that inhibits them.</p><p>The repetitive, <a href="http://dx.doi.org/10.1016/j.bbr.2014.05.057" target="_blank">stereotypic behaviors</a> that many animals adopt in captivity are caused by an imbalance of two neurotransmitters, dopamine and <a href="https://doi.org/10.1016/j.neubiorev.2010.02.004" target="_blank" rel="noopener noreferrer">serotonin</a>. This impairs the indirect pathway's ability to modulate movement, a condition documented in species from chickens, cows, sheep and horses to primates and big cats.</p>
The cerebral cortex, hippocampus and amygdala are physically altered by captivity, along with brain circuitry that involves the basal ganglia. Bob Jacobs, CC BY-ND<p>Evolution has constructed animal brains to be exquisitely responsive to their environment. Those reactions can affect neural function by <a href="https://www.penguinrandomhouse.com/books/311787/behave-by-robert-m-sapolsky/" target="_blank">turning different genes on or off</a>. Living in inappropriate or abusive circumstance alters biochemical processes: It disrupts the synthesis of proteins that build connections between brain cells and the neurotransmitters that facilitate communication among them.</p><p>There is strong evidence that <a href="https://doi.org/10.1523/JNEUROSCI.0577-11.2011" target="_blank">enrichment</a>, social contact and appropriate space in more natural habitats are <a href="https://doi.org/10.1111/j.1748-1090.2003.tb02071.x" target="_blank" rel="noopener noreferrer">necessary</a> for long-lived animals with large brains such as <a href="https://doi.org/10.1371/journal.pone.0152490" target="_blank" rel="noopener noreferrer">elephants</a> and <a href="https://doi.org/10.1080/13880292.2017.1309858" target="_blank" rel="noopener noreferrer">cetaceans</a>. Better conditions <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5543669/" target="_blank" rel="noopener noreferrer">reduce disturbing sterotypical behaviors</a>, improve connections in the brain, and <a href="https://doi.org/10.1038/cdd.2009.193" target="_blank" rel="noopener noreferrer">trigger neurochemical changes</a> that enhance learning and memory.</p>
The Captivity Question<p>Some people defend keeping animals in captivity, arguing that it helps conserve endangered species or offers educational benefits for <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.574.3479&rep=rep1&type=pdf" target="_blank" rel="noopener noreferrer">visitors to zoos and aquariums</a>. These justifications are questionable, particularly for <a href="https://animalstudiesrepository.org/acwp_zoae/8/" target="_blank" rel="noopener noreferrer">large mammals</a>. As my own research and work by many other scientists shows, caging large mammals and putting them on display is undeniably cruel from a neural perspective. It causes brain damage.</p><p>Public perceptions of captivity are slowly changing, as shown by the reaction to the documentary <a href="https://en.wikipedia.org/wiki/Blackfish_(film)" target="_blank" rel="noopener noreferrer">"Blackfish</a>." For animals that cannot be free, there are well-designed sanctuaries. Several already exist for elephants and other large mammals in <a href="https://www.elephants.com/" target="_blank" rel="noopener noreferrer">Tennessee</a>, <a href="https://globalelephants.org/overview/" target="_blank" rel="noopener noreferrer">Brazil</a> and Northern <a href="http://www.pawsweb.org/about_our_sanctuaries.html" target="_blank" rel="noopener noreferrer">California</a>. Others are being developed for large <a href="https://whalesanctuaryproject.org/" target="_blank" rel="noopener noreferrer">cetaceans</a>.</p><p>Perhaps it is not too late for Kiska.</p>
By Tara Lohan
Maybe we can blame COVID-19 for making it hard to hit the streets and gather signatures to get initiatives on state ballots. But this year there are markedly fewer environmental issues up for vote than in 2018.
While the number of initiatives may be down, there's no less at stake. Voters will still have to make decisions about wildlife, renewable energy, oil companies and future elections.
Here's the rundown of what's happening where.
Return of an Apex Predator<p>Wolves are on the ballot in Colorado. <a href="https://leg.colorado.gov/ballots/reintroduction-and-management-gray-wolves" target="_blank" rel="noopener noreferrer">Proposition 114</a> would require the state's Parks and Wildlife Commission to create a plan by 2023 for the reintroduction and management of gray wolves (<em>Canis lupus</em>) in areas west of the continental divide.</p><p>Gray wolves once roamed across the western United States but were mostly eradicated by the 1930s. Slowly efforts are being made to bring them back. The reintroduction of gray wolves to Yellowstone National Park in 1996 has been hailed as a <a href="https://www.theguardian.com/environment/2020/jan/25/yellowstone-wolf-project-25th-anniversary" target="_blank" rel="noopener noreferrer">rewilding success</a>.</p><p>"The argument is that by putting back in wolves — an apex predator that has evolved alongside their prey species — we're putting things back into ecological balance," University of Colorado Boulder ecology professor Joanna Lambert <a href="https://therevelator.org/wolf-reintroduction-colorado/" target="_blank">told <em>The Revelator</em></a> in a February interview about the science behind wolf reintroductions.</p><p>The Rocky Mountain Elk Foundation and the Colorado Farm Bureau are two of the top donors to the opposition groups.</p><p>The measure does include compensation for losses of livestock caused by gray wolves.</p><p>"What we're all hoping for is a landscape where we can coexist with the species that were originally here, but also acknowledging that humans need to make a living and that the costs of this initiative will be felt by some folks more than others," Lambert said.</p>
Confusion Over Clean Energy<p>In Nevada voters will take a second swing at a constitutional amendment to require that electric utilities source 50% of their electricity from renewables by 2030. Voters passed the same measure, <a href="https://www.nvsos.gov/sos/home/showdocument?id=8826" target="_blank">Question 6</a>, in 2018, but state law requires that constitutional amendments be passed in two consecutive even-numbered election years.</p><p>More clean energy for the state may seem good. But there's concern that enshrining 50% renewables by 2030 in the state's constitution isn't that ambitious and it will make it harder to continue the push for 100% renewables in the future. To do that would be another constitutional amendment that would again take four years and two consecutive ballot wins to move the needle.</p><p>Also, the state is already on its way to the same renewable goal.</p><p>A legislative effort to achieve 50% renewables by 2030 — but with a slightly different timeline for the increments to get there — was signed into law in April 2019 by Nevada Gov. Steve Sisolak. Renewable advocates hope the state will do even better than that benchmark, but passing Question 6 would make it harder.</p>
Paying a Fair Share<p>If California's <a href="https://www.sos.ca.gov/elections/ballot-measures/qualified-ballot-measures/" target="_blank">Proposition 15</a> passes, commercial and industrial properties will need to start paying taxes based on their current market value, instead of paying based on the purchase price from decades prior (which stems from Proposition 13 passed back in 1978). The initiative would exempt agricultural land, small businesses, renters and homeowners.</p><p>Reassessing the worth of large commercial properties could bring in between $7.5 billion and $12 billion a year that would go toward supporting local governments, school districts and community colleges.</p><p>Most of the <a href="https://ballotpedia.org/California_Proposition_15,_Tax_on_Commercial_and_Industrial_Properties_for_Education_and_Local_Government_Funding_Initiative_(2020)" target="_blank">opposition</a> has come from big business and anti-taxation groups.</p><p>The California Teachers Association Issues PAC is the biggest supporter of the effort, but a number of <a href="https://www.yes15.org/endorsers-environment" target="_blank" rel="noopener noreferrer">environmental groups</a> have also endorsed the measure, which would likely see oil companies and other big industrial polluters having to kick in more money.</p><p>"The oil industry has used Prop. 13 loopholes to evade tens of millions of dollars in property taxes," <a href="https://www.nrdc.org/experts/victoria-rome/nrdc-announces-support-californias-proposition-15" target="_blank" rel="noopener noreferrer">wrote Victoria Lome</a>, California legislative director for the Natural Resources Defense Council. "Companies like Chevron, Exxon, Phillips 66, Shell and Tosco are paying taxes based on assessments taken prior to 2000. Prop. 15 would end this hidden subsidy to dirty energy."</p><p>Oil companies could stand to lose in Alaska, too. Voters there will weigh in on <a href="https://ballotpedia.org/Alaska_Ballot_Measure_1,_North_Slope_Oil_Production_Tax_Increase_Initiative_(2020)" target="_blank" rel="noopener noreferrer">Ballot Measure 1</a>, which would increase taxes on big oil producers (those that have produced more than 400 million barrels overall or 40,000 barrels a day in the past year) operating in three established oil fields in the North Slope.</p>
Taking the Wind Out of the Sails of the Electoral College<p>Colorado's <a href="https://leg.colorado.gov/ballots/adopt-agreement-elect-us-president-national-popular-vote" target="_blank">Proposition 113</a> isn't about environmental issues directly but could cause big shifts in how presidential elections are run and what states and issues are considered important.</p><p>The initiative would add Colorado to the <a href="https://www.nationalpopularvote.com/written-explanation" target="_blank">National Popular Vote Interstate Compact</a>. That effort is aimed at ensuring the presidential candidate who wins the popular vote wins the election. It doesn't eliminate the Electoral College, but it saps its power.</p><p>The compact needs states representing at least 270 Electoral College votes to go into effect. It's currently at 196.</p><p>If Colorado's proposition is passed, and if the National Popular Vote Interstate Compact eventually gets enough votes to go into effect, then Colorado's nine electoral votes would go to the presidential candidate who wins the popular vote, not to the one who gets the most votes in Colorado.</p>
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