Featured Research

from universities, journals, and other organizations

Climate change implicated in decline of horseshoe crabs

Date:
September 1, 2010
Source:
United States Geological Survey
Summary:
A distinct decline in horseshoe crab numbers has occurred that parallels climate change associated with the end of the last Ice Age, according to a study that used genomics to assess historical trends in population sizes.

Horseshoe crabs congregate annually at Delaware Bay.
Credit: Greg Breese, U.S. Fish and Wildlife Service

A distinct decline in horseshoe crab numbers has occurred that parallels climate change associated with the end of the last Ice Age, according to a study that used genomics to assess historical trends in population sizes.

Related Articles


The new research also indicates that horseshoe crabs numbers may continue to decline in the future because of predicted climate change, said Tim King, a scientist with the U.S. Geological Survey and a lead author on the new study published in Molecular Ecology.

While the current decline in horseshoe crabs is attributed in great part to overharvest for fishing bait and for the pharmaceutical industry, the new research indicates that climate change also appears to have historically played a role in altering the numbers of successfully reproducing horseshoe crabs. More importantly, said King, predicted future climate change, with its accompanying sea-level rise and water temperature fluctuations, may well limit horseshoe crab distribution and interbreeding, resulting in distributional changes and localized and regional population declines, such as happened after the last Ice Age.

"Using genetic variation, we determined the trends between past and present population sizes of horseshoe crabs and found that a clear decline in the number of horseshoe crabs has occurred that parallels climate change associated with the end of the last Ice Age," said King.

The research substantiated recent significant declines in all areas where horseshoe crabs occur along the West Atlantic Coast from Maine to Florida and the eastern Gulf of Mexico, with the possible exception of a distinct population along the Yucatan Peninsula of Mexico.

These findings, combined with the results of a 2005 study by King and colleagues, have important implications for the welfare of wildlife that rely on nutrient-rich horseshoe crab eggs for food each spring.

For example, Atlantic loggerhead sea turtles, which used to feed mainly on adult horseshoe crabs and blue crabs in Chesapeake Bay, already have been forced to find other less suitable sources of food, perhaps contributing to declines in Virginia's sea turtle abundance. Additionally, horseshoe crab eggs are an important source of food for millions of migrating shorebirds. This is particularly true for the red knot, an at-risk shorebird that uses horseshoe crab eggs at Delaware Bay to refuel during its marathon migration of some 10,000 miles. Since the late 1990s, both horseshoe crabs and red knot populations in the Delaware Bay area have declined, although census numbers for horseshoe crabs have increased incrementally recently.

"Population size decreases of these ancient mariners have implications beyond the obvious," King said. "Genetic diversity is the most fundamental level of biodiversity, providing the raw material for evolutionary processes to act upon and affording populations the opportunity to adapt to their surroundings. For this reason, the low effective population sizes indicated in the new study give one pause."

These studies should help conservation managers make better-informed decisions about protecting horseshoe crabs and other species with a similar evolutionary history. For example, the 2005 study indicated males moved between bays but females did not, suggesting management efforts may best be targeted at local populations instead of regional ones since an absence of enough females may result in local extinctions.

"Consequently, harvest limitations on females in populations with low numbers may be a useful management strategy, as well as relocating females from adjacent bays to help restore certain populations," King said. "Both studies highlight the importance of considering both climatic change and other human-caused factors such as overharvest in understanding the population dynamics of this and other species."

Background on Horseshoe Crabs

Horseshoe crabs are not crabs at all -- in fact, they are more closely related to spiders, ticks and scorpions. While historically horseshoe crabs have been used in fertilizer, most horseshoe crab harvest today comes from the fishing industry, which uses the crab as bait, and the pharmaceutical industry, which collects their blood for its clotting properties. While the crabs are returned after their blood is taken, the estimated mortality rate for bled horseshoe crabs can be as high as 30 percent.

The research was published in the June issue of Molecular Ecology and was authored by Sψren Faurby (Aarhus University, Denmark), Tim King, Matthias Obst (University of Gothenburg, Sweden) and others.

The 2005 study was published in the Transactions of the American Fisheries Society and authored by Tim King, Mike Eackles Adrian Spidle (USGS) and Jane Brockman (University of Florida).


Story Source:

The above story is based on materials provided by United States Geological Survey. Note: Materials may be edited for content and length.


Journal References:

  1. Sψren Faurby, Tim L. King, Matthias Obst, Eric M. Hallerman, Cino Pertoldi, Peter Funch. Population dynamics of American horseshoe crabs-historic climatic events and recent anthropogenic pressures. Molecular Ecology, 2010; 19 (15): 3088 DOI: 10.1111/j.1365-294X.2010.04732.x
  2. Tim L. King, Michael S. Eackles, Adrian P. Spidle, H. Jane Brockmann. Regional Differentiation and Sex-Biased Dispersal among Populations of the Horseshoe Crab Limulus polyphemus. Transactions of the American Fisheries Society, 2005; 134 (2): 441 DOI: 10.1577/T04-023.1

Cite This Page:

United States Geological Survey. "Climate change implicated in decline of horseshoe crabs." ScienceDaily. ScienceDaily, 1 September 2010. <www.sciencedaily.com/releases/2010/08/100830131344.htm>.
United States Geological Survey. (2010, September 1). Climate change implicated in decline of horseshoe crabs. ScienceDaily. Retrieved November 23, 2014 from www.sciencedaily.com/releases/2010/08/100830131344.htm
United States Geological Survey. "Climate change implicated in decline of horseshoe crabs." ScienceDaily. www.sciencedaily.com/releases/2010/08/100830131344.htm (accessed November 23, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, November 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) — The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
NY Gov. on Flood Prep: 'prepared for the Worst'

NY Gov. on Flood Prep: 'prepared for the Worst'

AP (Nov. 23, 2014) — First came the big storm. Now comes the big melt for residents of flood-prone areas around Buffalo. New York's governor says officials are preparing for the worst as the temperature is expected to rise and potentially melt several feet of snow. (Nov. 23) Video provided by AP
Powered by NewsLook.com
Anglerfish Rarely Seen In Its Habitat Will Haunt You

Anglerfish Rarely Seen In Its Habitat Will Haunt You

Newsy (Nov. 22, 2014) — For the first time Monterey Bay Aquarium recorded a video of the elusive, creepy and rarely seen anglerfish. Video provided by Newsy
Powered by NewsLook.com
Raw: Buffalo Residents Digging Out, Helping out

Raw: Buffalo Residents Digging Out, Helping out

AP (Nov. 22, 2014) — Hundreds of volunteers joined a 'shovel brigade' in Buffalo, New York on Saturday, as the city was living up to its nickname, "The City of Good Neighbors." Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins