Archives for February 2017
AgriLife Researcher points to more Amazon rainforest droughts
COLLEGE STATION — Climate change from political and ecological standpoints is a constant in the media and with good reason, said a Texas A&M AgriLife Research scientist, but proof of its impact is sometimes found in unlikely places.
“Discussions of climate change usually are focused on changes occurring in polar and temperate zones, but tropical regions also are expected to experience changes in regional precipitation,” said Dr. Kirk Winemiller, AgriLife Research fisheries scientist and Regents Professor in the department of wildlife and fisheries sciences at College Station.
Winemiller and his Brazilian colleagues analyzed a long-term database, 1999-2014, of fish survey statistics and hydrology in the central Amazon and discovered a direct correlation between water quantity and quality with the types and number of fish species found.
“The change occurred following the severe drought in that region in 2005, and the hydrologic regime and fish assemblage have not returned to their previous states since,” Winemiller said.
The research report, “Simultaneous abrupt shifts in hydrology and fish assemblage structure in a floodplain lake in the central Amazon,” was published recently in Scientific Reports, the online publication of Nature.
To view the paper in its entirety and the collaborating author list, go to 10.1038/srep40170.
“The Amazon region is showing evidence of altered rainfall patterns,” Winemiller said. “Until this study, with few exceptions, studies of potential effects of climate change in the Amazon have focused on forests and other organisms on land.
“Since the drought, many fish species are less abundant within the study area, while others have increased. Smaller species with high reproductive rates have increased, while large species, including those with the highest consumer market value, have become less prevalent.”
As an example, Winemiller cited the relative abundance of the tambaqui,Colossoma macropomum, one of the region’s most valuable species in Amazon fish markets, declined in relative abundance within the study area after the 2005 drought and has not increased its numbers since. He said the species feeds on fruits and seeds in flooded forests and is sensitive to changes in the annual flood regime hydrology.
Winemiller said the changes within the fish species appeared to be associated with how the fish species respond differently to changes in habitat quality and the connectivity of the river channel with aquatic habitats in the floodplain at various water levels and times of the year.
“The study reveals that climate change is impacting tropical regions with consequences not only for terrestrial ecosystems, but for aquatic ecosystem dynamics, biodiversity and fisheries as well,” he said. “It shows that future fisheries management in tropical regions will need to account for how changes in precipitation and hydrology influence ecological factors affecting fish stocks.”
Originally appeared: http://today.agrilife.org/2017/02/16/melting-polar-ice-rising-sea-levels-not-climate-change-dangers/
Writers: Paul Schattenberg, 210-859-5752, firstname.lastname@example.org
Steve Byrns, 325-653-4576, email@example.com
Contacts: Dr. Roel Lopez, 210-277-0292, firstname.lastname@example.org
Dr. Nova Silvy, 979-845-5749, email@example.com
Dr. Israel Parker, 979-739-0679, Israel.firstname.lastname@example.org
SAN ANTONIO – For the past several months, a Texas A&M University System institute has been actively involved in efforts to quash a screwworm outbreak in Florida that has jeopardized an already endangered species, said the director for the Institute of Renewable Natural Resources.
“While there had been no screwworm outbreaks in the U.S. for the past 30 years, one began last July on Big Pine Key, which affected the Key deer population,” said Dr. Roel Lopez, institute director and co-principal investigator for the Key deer study, San Antonio.
Key deer are a diminutive subspecies of white-tailed deer found only in the Lower Florida Keys.
Over the following months, screwworms infested the population, which is spread across more than 20 islands. It has led to 135 Key deer deaths, including 83 that were euthanized to reduce the risk of further infection.
“This was a significant blow to a species of which is uniquely located in that area and has an estimated population of just 875,” said Lopez, who noted the mortalities were primarily among adult males.
He said the institute, which is affiliated with the Texas A&M AgriLife Extension Service, Texas A&M AgriLife Research and Texas A&M’s College of Agriculture and Life Sciences, was brought in to work with the U.S Fish and Wildlife Service, U.S. Department of Agriculture, Florida Fish and Wildlife Service Commission, Florida Department of Agriculture and Consumer Services of Monroe County.
“With the U.S. Fish and Wildlife Service as the lead agency, we have been researching screwworm impacts and spatial distribution, as well as deer population density based on sex ratio and age,” Lopez said. “We have also been involved in determining management implications for protecting the deer. In particular, the Texas A&M institute’s efforts have been focused on helping determine how this endangered species will fare following the infestation.”
He said a complete survey of the Key deer had not been conducted since 2005.
“At the invitation of the U.S. Fish and Wildlife Service and Florida agencies, our staff and research scientists have conducted multiple surveys to obtain the current estimate of the population, focusing efforts on Big Pine and No Name keys, the core area for the population.”
Lopez and co-principal investigator Dr. Nova Silvy, Regents Professor in Texas A&M’s wildlife and fisheries sciences department, College Station, both did their doctoral research on Key deer.
“All but 10 of the Key deer deaths from screwworm infestation were males,” Silvy said. “In these males, screwworms typically infected open wounds created by their fighting during their rutting season, which is from September to December, as they competed for females.”
He explained screwworm fly larvae feed on warm-blooded animal tissue, so the open wounds from the deer rut provided an environment for screwworms to infest and lay eggs.
“The screwworms eat the flesh around the wound until the deer becomes incapacitated or dies,” he said.
According to Dr. Israel Parker, a research scientist at the institute in College Station and another co-principal investigator for the study, the screwworm infestation could also cause problems for other warm-blooded animals in the area. For his master’s degree work at Texas A&M, Parker was involved in the translocation of Key deer during the 2005 survey.
“Screwworms can have devastating effects on livestock populations, so an outbreak could potentially affect many agricultural operations, depending on how widely it spreads,” he said. “The last major infestation of the screwworm in the 1960s was a significant concern for livestock producers in Texas, so it’s very important screwworms be addressed in the Florida Keys before they possibly spread and affect livestock operations on the mainland.”
Silvy noted while so far interagency efforts have been highly successful in halting the outbreak, further screwworm infestations may appear in the spring as Key does start giving birth.
“The flies could infest the afterbirth or the navels of the fawns, which is a common problem with calves in areas with screwworms,” he said.
To help control the outbreak and assess the survivability of the Key deer, Lopez, Silvy, Parker and others from the Texas A&M institute have traveled to Florida to conduct deer population estimates and projections. They have also placed radio collars on 30 Key deer does to help find if they may be vulnerable to screwworm flies while giving birth.
“Working together, our agencies have been able to stave off further screwworm infestations,” Lopez said. “Additionally, the institute’s male-to-female population ratio estimate showed a high probability the Key deer population will continue to be viable because the adult males that died can be replaced by younger males that can mate with multiple does.
“Estimates indicate there appear to be enough males to complete the breeding season. They also show a long-term population increase of about 3.5 percent annually, which should continue.”
Lopez said preventive treatment and screwworm fly eradication efforts by other cooperating agencies have been highly successful. These have included setting up feeder stations rimmed with anti-parasitic medications and releasing 60 million sterile male screwworms to mate with wild female flies, stifling their reproductive capacity.
“In addition, several deer enclosures are proposed to be built at the National Key Deer Refuge to trap and care for healthy specimens if herd numbers become uncomfortably low,” he said.
Lopez said he hopes these strategies, in addition to continuing the monitoring protocol, conducting intensive monthly surveys, possible translocation and long-term monitoring of outer Key islands impacted by screwworm, will help ensure the survival of the Key deer.