Larry Niles’s working life has been spent conserving wildlife as a biologist for government agencies, academic institutions and non profit conservation groups. His career began as a regional game biologist in Georgia where he led projects on white tailed deer population management and studies of black bears in the Okeefenochee Swamp. In 1982 Niles joined the NJ Endangered Species Program. Over the next 25 years he spearheaded research and management projects on shorebirds, colonial water birds, migrate songbirds and raptors and directed work on many other bird, reptile and invertebrate species. He is featured in Nature’s Crash: A Tale of Two Species.

How are current red knot populations doing?

Well, I believe we did the film in 2008. In both 2009 and 2010 the population remained stable in Bahia Lomas, that’s the main wintering area for red knots and in a few other wintering areas in South America. In the U.S. the numbers more or less remained stable. So we were hopeful that it had bottomed out. With species like this it takes a long time to recover because they are a low-productivity species, so once they get down to a certain level it takes decades for the population to get back to where it was. We knew that the recovery would be slow.

But this year, 2011, in Tierra del Fuego the number of birds went from 16,000 down to 11,000. They had a similar decline in an aerial count done two weeks earlier in the exact same area. Two surveys verify that there were less birds in Bahia Lomas. The Aircraft survey went down to Argentina in Rio Grande and found 400 in a place where there were 800 last year. In the year 2000, we counted 56,000 red knots in these two places. And now, based on the aerial count, we have less than 10,000. And what’s even more alarming is we had at least a 5,000 bird decrease in one year. We don’t know exactly what that means yet. It’s bad for sure.

The first question is, Did the birds move somewhere else? We covered all of Tierra del Fuego but we didn’t cover the area north of the Strait of Magellan because those places had blanked out years ago. We didn’t see the need to survey them. Next year we will expand the area of our survey. But another way for us to check this to see if it was an actual decline in numbers or if the birds have just moved around is back in Delaware Bay. The counts in Delaware Bay trend the same. We’re going to wait and see what happens in Delaware Bay.

We saw a lot of juveniles in the flock, and that’s a good thing. It means that birds left Delaware Bay in good condition, got to the Arctic, and the Arctic was reasonably hospitable for breeding. But it’s alarming because, in normal years we don’t have many juveniles. So if you were compare the numbers from this year to last year and just looking at adult red knots, the drop would’ve been much more. The count this year was inflated a bit by the production of juveniles.

So this is a very uncertain situation. If you have a loss of 5,000 birds when a population is 100,000 then it’s significant but it’s not going to determine the fate of the population. But when you have 16,000 and you lose 5,000 then that’s a very significant thing. It’s not likely that this decline is related to Delaware Bay because it’s so dramatic. But the collapse of Delaware Bay brought the population down to this low level. Now natural forces could wipe it out.

So the collapse of Delaware Bay might have started off this trend of decline but now there are other factors at play that are affecting populations?

Yes, we think that the main affect of the collapse of Delaware Bay as a stopover was the poor production of juveniles. Ideally, birds leave Delaware Bay for the Arctic, breed and produce a crop of juveniles. But because birds were leaving Delaware Bay in poor condition due to the lack of crab eggs, they reached the Arctic and either didn’t breed or bred unsuccessfully. So as adults died they weren’t being replaced by juveniles and the population went down.

The other impact of Delaware Bay is that if birds leave Delaware Bay in poor condition and hit bad conditions on the way to the Arctic or in the Arctic the adults may die before getting a chance to breed. If Delaware Bay was doing what it should be those birds would have lots of fat and they could live off that fat until conditions improve. But if they don’t have that fat, it’s like being in the Arctic without a winter coat.

When you bring a population of animals down to a low level, you still have all the other natural influences. One of the natural influences would be the hurricanes and tropical storms coming through the Atlantic and Caribbean when the birds are going south. These may be increasing because of climate change, but they’ve always been a problem. A red knot might spend up to 4-5 days over ocean before it hits land. If it encounters a storm and is blown off course it may not make it. Say this happens and 5,000 birds are killed in a season. If there are 100,000 birds, that’s 5 percent of the population. But if you have a lower number, 25,000 birds, now it’s 20 percent of the population. If it’s 15,000, then that’s a third.

And you mentioned climate change causing more harsh weather conditions. Has climate change also affected the Arctic breeding grounds in an adverse way for the red knots?

It’s hard to say what’s happening in the Arctic. Our group of knots breed mostly in the Archipeligo islands in Canada just above the Arctic circle. The habitat is of a higher elevation and barer because of that. It’s around 75 percent snow-covered. There’s a reason for that because they’re trying to nest in areas that have a very low predation rate. If climate change generally warms things, then I don’t know what their new strategy would be. Would they go to a higher altitude? Would they go to more northern islands? We don’t know enough about the effect of climate change in breeding areas.

But in temperate and tropic areas I think it can have a significant impact. We tracked a bird last year with a geo-locator, a device that stores information, that encountered a tropical storm on its way south and flew over 1,000 miles off course out to sea. It was lucky enough to make it back and successfully land in the northern coast of Brazil. But birds are physiology planning on a flight to Brazil. They aren’t planning on a 1000 mile detour.

Have the horseshoe crabs had a similar decline recently?

The major decline took place during the 90s and the early 2000s. Then they bottomed out in 2003. But in the last few years, the surveys have been in conflict. Some surveys suggest there have been an increase in the number of eggs on the beach, some are showing no increase. There has been an increase in the number of juveniles. I think it has gotten better but I don’t think there is significant statistical basis for that.

Another way of looking at it, when we make our catches of shorebirds each year we compare the percent of birds that make 180 grams because 180 grams is more or less the threshold weight that we estimate birds need to successfully breed in the Arctic. Back in 1998, 80 percent of the birds that we caught at the end of the season were over 180 grams. In the worst of it we were getting 5 percent of birds making it to 180 grams. Last year it was 40 percent. So that’s an improvement. But it’s an improvement with a population that’s a quarter of the size that it once was. So naturally you need less eggs because you have fewer birds.

What can people do in order to stabilize and improve the populations at red knots?

Well, I think there’s two things. First, we should really not be harvesting crabs until there’s clear signs of improvement. There are still 400,00 crabs killed each year for bait. One thing people could do is keep the pressure on their legislatures, especially the people in New Jersey, Pennsylvania, Delaware, Maryland and Virginia.

The second thing is that people need to become more aware of the situation of shore birds. We’re talking about the red knot but we now have evidence that sandpipers and even common species like lesser yellowlegs have declined by 80-90 percent in the last 20 years. So what we are looking at with red knots is a serious decline but all the arctic nesting shore birds are in trouble.

In the 1930s, when water fowl were in trouble, the sportsmen started programs, duck stamps, paying taxes on their guns and ammunition — they did things that ultimately led to the restoration of water fowl populations. I would say, people who like birds need to start doing something. It’s not just governments or conservation groups. If the hunters had left it up to governments and groups then we probably wouldn’t have any water fowl species right now. But they didn’t. They took control. And I think now is the time for people who like birds to start doing something, start demanding that they tax binoculars and put that money into programs, or demand that there is a shore bird stamp and the money raised would go toward restoration programs. I think there is need for serious action now.

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The horseshoe crab has been on Earth for 350 million years. An ancient and complex anatomy hides within its domed shell. From its 10 eyes to its tube-like heart, the horseshoe crab’s unique physique may surprise you.

SHELL

When you first look at a horseshoe crab, chances are the first thing that grabs your attention is its large, hard carapace, or shell. Like all invertebrates, the horseshoe crab lacks an internal skeleton. Instead, this external shell acts as an exoskeleton, providing structure from the outside and protection to the animal against predators or other threats. Made of the cellulose-like material called chitin, the shell is so hard that only sharks or sea turtles can penetrate it. The crab will shed its shell continually throughout its lifetime, as many as 17 times, including four times while still inside the egg.

The carapace of the horseshoe crab is made up of three sections: the cephalothorax, abdomen and tail. The largest section of the animal, the cephalothorax, houses parts of the intestinal tract, nervous system and circulatory system. The size of the cephalothorax differs greatly between males and females. A female’s cephalothorax can reach almost twice the size of a male’s. Attached by a hinge to the cephalothorax, the abdomen contains the musculature for the operation of the book gills and the tail. The tail is attached to the abdomen at the terminal base. Misunderstood as a stinger, the tail is not at all poisonous. It acts as the horseshoe’s rudder, helping it steer and right itself if it gets flipped on its back by the surf.

MOUTH & LEGS

Flip the animal over (gently) and you’ll easily see its six pairs of feeding and walking appendages. Starting from the front of the crab, the first pair of appendages is called the chelicerae. These are feeding appendages used to place food into the animal’s mouth. Going down the body, the next pair of appendages is the pedipalps. These are the first walking legs and they enable the horseshoe crab to move along the rugged seafloor. Each pedipalp has a small claw at the tip except the last pair, the pusher legs. This pair of legs is used for locomotion but also has been equipped with a leaf-like structure that is used for pushing and clearing away sediment as the crab burrows into the sea floor.

NERVOUS SYSTEM

Don’t let its hard exterior fool you. The horseshoe crab is actually quite a sensitive creature. This invertebrate uses a system of specialized nerves that extend from the brain throughout the body. Several large nerves supply the crab with information about its surroundings, including two optic nerves and eight pairs of hemal nerves that are spread throughout the body.

An interesting feature of the pusher leg is the flabellum, an organ that tests the composition of the water passing to the gill chamber. There are approximately one million sensory cells in this organ alone.

The horseshoe crabs uses its tail as a rudder, and to help it turn over when it gets flipped upside-down.

EYES

A total of 10 eyes help the horseshoe crab get around. These eyes are distributed around the body including on top of its shell, on the tail and near the mouth to help orient the animal when swimming.

Two compound eyes are easily seen on each side of the animal’s shell. The main function of this set of eyes is to find mates during the spawning season.

LUNGS AND HEART

On the horseshoe crab’s underside is a series of six page-like structures called book gills. These organs absorb oxygen from the water while keeping the water out. Each gill contains approximately 150 large flap-like membranes called lamellae that look like pages in a book.

The book gills are versatile organs used not only to breathe but also for swimming. Swimming is an alternative mode of transportation used in emergencies, mainly to escape from predators or if the animal finds itself in rough surf. The gills also function as paddles to propel juvenile horseshoe crabs through the water.

The horseshoe crab’s heart is a long tube that runs down the middle of the cephalathorax and abdomen, extending almost the entire length of its body. On average, the heart rate of the horseshoe crab is about 32 beats per minute.

For many decades, humans have harvested the horseshoe crab for use as fishing bait. Since the 1970s, we have also used horseshoe crab blood for medical purposes. But we may have gone too far. Horseshoe crab numbers have declined significantly since the early 1990’s. And, naturally, so did their egg numbers.

This is especially important to a small shorebird that is a global traveler of the most impressive kind. The red knot makes one of the longest migrations of any animal — a journey that takes it from one end of the earth to the other. To accomplish this feat, it relies on the eggs of the horseshoe crab. Without these eggs, the red knot is in danger.

In the film Crash: A Tale of Two Species, filmmaker Allison Argo tells the story of nature’s amazing ability to create fragile connections among the most unexpected creatures, and of our potential as humans to destroy those connections — or restore them.

To order a copy of Crash: A Tale of Two Species, visit the NATURE Shop.

Online content for Crash: A Tale of Two Species was originally posted February 2008.

This is the story of the fabric of life, and how every species is interconnected – each one important, no matter how big or small.  At its center is the humble horseshoe crab, a creature which has remained virtually unchanged for 350 million years.  Its annual spring spawning produces millions of eggs that are the lifeline for a tiny bird called the red knot, which migrates 10,000 miles from South America to the Arctic each year. Scientific and medical communities have discovered that the crab also provides an indispensable testing agent for drugs and vaccines, as well as resources for human optics and burn treatment.  But horseshoe crab numbers are plummeting from their new use as bait for the fishing industry, dropping by two-thirds or more since 1990.  And the precious pyramid depending on this age-old creature is about to come crashing down. Filmed and presented on television in high definition. Buy the DVD. This film premiered February 2008.

The horseshoe crab is at the center of a contentious debate, and one that plays the world over. How do we find the balance between man and nature?

In the Delaware Bay, the clash over horseshoe crabs has embroiled experts, agencies and people in a heated debate that pits the survival of the red knot against the livelihood of fisherman and the U.S. pharmaceutical industry.

And, in order to find a solution, The Audubon Society, the Atlantic States Marine Fisheries Commission, the New Jersey Department of Environmental Protection, the U.S. Fish and Wildlife Service, conservationists and long-time bay watermen are all looking for one thing, an answer to how many horseshoe crabs there are – and how many there need to be to maintain the ecological balance of the bay if the red knot is to have any hope of survival.

Little is known about the status of the horseshoe crab population. Because their population has only been studied recently, there is limited data which makes it difficult to assess its status. What is known is that prior to 1998, millions of horseshoe crabs were taken from the Delaware Bay in an unregulated fishery. But now, attention is being paid.

Based on recent survey data, the Delaware Bay population appears stable. Dr. Dave R. Smith, Aquatic Ecology Lab, USGS believes evidence from recent assessments and monitoring data indicate that the horseshoe crab population in the Delaware Bay region is experiencing positive population growth. Recent surveys have shown significant increases in the numbers of juveniles and adult horseshoe crabs. These encouraging signs provide hope for the horseshoe crab and shorebird connection in Delaware Bay.

Dr. Smith believes these gains are most probably in response to direct action taken by the fisheries commission because of declining migratory shorebird populations. In 2000, the Atlantic States Marine Fisheries Commission (ASMFC) established state-by-state quotas in all Atlantic states for crabs harvested for bait, limiting the number of horseshoe crabs that could be harvested. And, in 2006, the ASMFC further reduced the number of horseshoe crabs that could be caught in Delaware and New Jersey to 150,000 per year and added additional protection in Maryland and Virginia to increase horseshoe crab abundance in and around the Delaware Bay.

Another crucial step was the establishment of a no-harvest zone (the Carl Shuster Reserve) in the ocean off the mouth of the Delaware Bay. The aim of the no-harvest zone is to protect older juvenile and newly mature female horseshoe crabs from being harvested, allowing them to reach sexual maturity and begin reproducing. Dr. Smith believes that the current management program, which allows only male horseshoe crabs to be caught and taken, will allow for a growth in the population of horseshoe crabs in the bay. Recent monitoring data shows that the number of spawning males has continued to increase significantly in the bay, even with the male-only harvest restrictions in place.

Monitoring programs are in place that will detect important declines in male to female ratios if fisheries managers decide to continue with the current management strategy.

But, according to Dr. Smith, it is important to understand that the harvesting of horseshoe crabs is not the only thing that is keeping their population from growing. Whether the horseshoe crab can ever return in their former numbers is uncertain. They are being threatened by other factors – consequences of climate change and habitat loss loom large on the horizon.

Censusing horseshoe crabs is an imprecise science, and interpretation of survey results may vary. Dr. Larry Niles, Chief Biologist, Conserve Wildlife Foundation, acknowledges the important efforts made by the ASMFC in the past ten years and the possibility that the horseshoe crab population may be increasing. However, Dr Niles believes this improvement, if not a temporary up tick in numbers, is not matched by other surveys done on the Delaware Bay shore where shorebirds are feeding.

Over the six year history of the spawning survey, Niles states there has been no improvement in the number of spawning females. More importantly, surveys of horseshoe crab eggs in New Jersey and Delaware, the food on which the red knots depend, have also shown no sign of improvement in population numbers. In 2007, New Jersey counts of the number of horseshoe crab eggs were the lowest in the history of the survey.

Shorebird biologists found a corresponding 30 percent decline in red knot numbers in 2007 compared to two years ago. Dr. Niles believes it is vital that there are no more losses to the red knot population associated with inadequate availability of horseshoe crab eggs on the Delaware Bay and will continue to argue for further harvest restrictions to assure increases in breeding female horseshoe crabs and their eggs so vital to the red knot.

And yet, it still may be too late for the red knot. Published population models of the red knot indicated that the bird will be at or near extinction in 2010 – just two years from now. Since horseshoe crabs take 10 years to reach sexual maturity, even the restrictions in place now may not be enough to increase this vital food supply for the red knots and ensure their survival. 

But, it is not only the survival of the red knot that is at stake. Like the proverbial canary in the coal mine, the red knots’ decline and potential extinction is a warning sign of larger consequences and danger to come. If steps are not taken to protect our unique ecosystems and wildlife, they may disappear forever. 

It fuels the journeys of shorebirds along the Eastern Seaboard and feeds some loggerhead sea turtles and sharks. The horseshoe crab is intricately woven into the web of life. Yet this harmless and primitive sea creature not only plays a key role in nature, it occupies a crucial place in the human world as well.

Over three decades ago, medicine claimed this ancient animal as a new life-saving tool. In 1971 researchers discovered that when they exposed the horseshoe crab to E. coli bacteria, the crab’s blood clotted. The clotting indicated the presence of endotoxins, toxic substances released by E. coli and other gram-negative bacteria that could produce severe symptoms in exposed humans such as fever or hemorrhagic stroke.

The simplicity of its immune system is actually what makes the crab’s blood useful to our biomedical industry. Horseshoe crabs live under the constant threat of infection in a habitat that can easily contain billions of bacteria per milliliter. To fight off infection, the horseshoe crab has a compound in its blood — LAL, or Limulus Amebocyte Lysate — which immediately binds and clots around fungi, viruses, and bacterial endotoxins.

LAL’s endotoxin binding and clotting ability is what makes it so invaluable to our own pharmaceutical industry. Once the LAL test was recognized by the Food and Drug Administration (FDA) as an alternative to then current methods of testing for endotoxins, the pharmaceutical industry tapped in. Horseshoe crabs were abundant, their blood easy to harvest and the test took only one hour.

Today, LAL has become the worldwide standard screening test for bacterial contamination. Every drug certified by the FDA must be tested using LAL, as do surgical implants such as pacemakers and prosthetic devices.

Horseshoe crab blood has not only become a key weapon in our medical arsenal, it has also become big business. On the world market, a quart of horseshoe crab blood has a price tag of an estimated $15,000, leading to overall revenues from the LAL industry estimated at U.S. $50 million per year. But that pales in comparison to its value to the pharmaceutical industry.

Of course, to obtain LAL you need horseshoe crabs — and lots of them. According to the Atlantic States Marine Fisheries Commission, that $50 million dollar industry requires the blood of approximately 250,000 horseshoe crabs.

While the blood of a horseshoe crab can be extracted without killing the animal, there is some question of how harmful bleeding is to the animals. The LAL industry says the bleeding causes no long-term injury.

Adult horseshoe crabs are collected by trawlers and transported to the LAL lab, where they are washed to remove sand and other marine debris from their exoskeletons. Those crabs without visible injuries are placed on a rack and bled with a large-gauge needle. Up to 30% of the crab’s blood is removed. Within 72 hours, the bled horseshoe crabs are returned to the water, where their blood volume rebounds in about a week.

LAL manufacturers have measured mortality rates of less then 3%. Yet two recent studies estimate that between 10% and 15% of crabs do not survive the bleeding procedure, which accounts for the mortality of 20,000 to 37,500 horseshoe crabs per year. Another concern is that it takes the crab a few months to rebuild its blood cell count level back up after a bleeding. Horseshoe crabs could be bled up to three or four times a year, which would take a toll on the health of the animals. But LAL manufacturers claim they only bleed them once a year.

Whether we can or will protect the health of horseshoe crabs for their own benefit, for the good of other creatures, or for our own use remains to be seen. Despite supporting the fishing industry for over 100 years, the condition of horseshoe crab populations has largely been ignored by fishery managers until recently. With growing concern over declining populations, regulations on the harvest of Horseshoe Crabs have just recently been imposed, though some states are already loosening restrictions.

Perhaps science can step in and “give back” to the animal for all of the good it has done us. Researchers are focusing their attention on producing LAL without the horseshoe crab, exploring the potential to cultivate and produce LAL from other sources.

WEB SITES

Horseshoe Crabs

HorseshoeCrab.org
http://horseshoecrab.org/
Comprehensive Web site exploring the anatomy, evolution, conservation, and research on the horseshoe crab. Also visit http://horseshoecrab.org/act/act.html for information on how to get involved in helping the horseshoe crab.

Green Eggs & Sand Educational Program
http://www.dnr.state.md.us/education/are/ges.html
A Tri-State Horseshoe Crab/Shorebird Education Program for middle and high schools students.

University of Delaware Sea Grant College Program
http://www.ocean.udel.edu/horseshoecrab/
Web site designed to provide the public with research-based information about the horseshoe crab. Plus, information on artificial bait to replace horseshoe crab meat: http://www.ocean.udel.edu/horseshoecrab/Research/bait.html

Horseshoe Crab Research Center
http://www.nmfs.vt.edu/HSCwebsite/index.htm
The goal of the Horseshoe Crab Research Center (HCRC) is to provide information required to sustainable manage the horseshoe crab resource for the benefit of all resource users.

Dupont Nature Center – Red Knot & Horseshoe Crab
http://www.dupontnaturecenter.org/explore.html
Owned and operated by the Delaware Division of Fish and Wildlife, this center offers one of the best viewing areas for spawning horseshoe crabs and migratory shorebirds during the peak season.

Red Knots

The Shorebird Project
http://shorebirdproject.blogspot.com/
Larry Niles, featured in “Crash: A Tale of Two Species, and an international team of biologists who monitor red knots and other shorebirds blog about the ongoing news surrounding red knots and other shorebirds.

Friends of the Red Knot
http://mysite.verizon.net/vzeu3rwf/
Friends of the Red Knot is a club whose members are working to have the Red Knot bird placed on the Endangered Species List.

Shorebirdworld.org
http://www.shorebirdworld.org/index.php
Organization dedicated to promoting understanding and awareness of the natural history of shorebirds.

New Jersey Division of Fish and Wildlife
http://www.nj.gov/dep/fgw/ensp/redknot.htm
NJ Division of Fish and Wildlife’s page on Red Knot Population and Conservation.

American Bird Conservancy
http://www.abcbirds.org/abcprograms/science/watchlist/red_knot.html
ABC’s mission is to conserve native wild birds and their habitats throughout the Americas.

Birding and Conservation

All About Birds
http://www.birds.cornell.edu/AllAboutBirds/
All About Birds is Cornell Lab of Ornithilogy’s Web site for bird basics. Includes info on identifying birds and birding hotspots.

Audubon
http://audubon.org/
Audubon’s mission is to conserve and restore natural ecosystems, focusing on birds, other wildlife, and their habitats for the benefit of humanity and the earth’s biological diversity.

eBird
http://ebird.org/content/ebird/
A real-time, online checklist program for bird sightings.

Manomet
http://www.manomet.org/
one of the nation’s oldest independent environmental research organizations, Manomet conducts original research on natural systems and wildlife.

Defenders of Wildlife
http://www.defenders.org/index.php
One of the country’s leaders in science-based, results-oriented wildlife conservation.

Wildlife Conservation Society
http://www.wcs.org
Search the WCS Web site for a wealth of information about horseshoe crabs and red knots — as well as about how their fates are intertwined.

BOOKS

Harrington, Brian. The Flight of the Red Knot: A Natural History Account of a Small Bird’s Annual Migration from the Arctic Circle to the Tip of South America and Back. W. W. Norton & Company, 1996.

Crensen, Victoria. Horseshoe Crabs and Shorebirds: The Story of a Food Web. Marshall Cavendish Corporation, 2003.

This Teacher’s Guide accompanies the NATURE program Crash: A Tale of Two Species. The program looks at the interconnection between two very different animals — the horseshoe crab and the red knot — and the threats to their survival.

Lessons in the guide use the programs as a starting point for discussions and activities that focus on adaptations that help these animals survive, the ways that human activity can endanger different species, and the varieties of wildlife in your own community. This guide includes teacher’s pages and student activity masters that can be used with the program. Please photocopy the pages and hand them out to students in class.

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