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Who’s eating all the shrimp?

26Apr

Download PDF: Who’s eating all the shrimp?

Abstract

Whether in prawn cocktail, shrimp gumbo, or grilled on the barbeque, you’ve probably eaten shrimp lots of times. It’s the most common seafood in the US. An American eats on average 4 pounds of it every year!

While we know that shrimp is a popular seafood, we wanted to find out how important it was in supporting other valuable fish species in the Gulf of Mexico.

We studied the relationship between the abundance of shrimp and the fish that eat them, and found that there was a statistical link between the two. Although we cannot conclude that this is entirely due to the abundance of shrimp, we believe that our research shows that shrimp are a really important prey for these fish species.

Introduction

Figure 1:
White and brown shrimp. Most shrimp are grey or transparent while alive but they turn pink when we cook them.

Shrimp fishing is big business in the Gulf of Mexico! In fact, it’s the most valuable fishery in the entire Gulf region, contributing a whopping 65% of all US shrimp (Fig. 1). But that’s not the only reason why shrimp are valuable…

Recent studies have shown that shrimp might be a very important prey for larger fish. We call this type of species forage species, which means that if their population falls, it will have a negative impact on the populations of the fish that eat them (their predators).

Three of the major predators of young (juvenile) shrimp in the Gulf of Mexico are southern flounder, spotted seatrout and red drum. These fish are really important for recreational and/or commercial fisheries. The potential decrease in shrimp abundance is a big ecological concern because of its role as prey supporting many valuable predators, such as these fish species.

In this study, we wanted to find out how important shrimp were as a forage species for these fish.

Methods

From 1986 to 2014 the Texas Parks and Wildlife Department (TPWD) used different types of nets to collect samples of white shrimp and brown shrimp, and three fish species: southern flounder, spotted seatrout and red drum (Fig. 2). Juveniles and young adults of these fish prey upon shrimp, so these were the stages included in our statistical analysis.

While sampling took place monthly for shrimp, we found more brown shrimp in May and more white shrimp in August and November than during any other months. We used shrimp data from these months in the analysis and matched these data to the closest spring and fall catch data available for the fish.

We converted these data into an indicator known as catch-per-unit effort (CPUE), which in this case is the number of individuals of each species caught per hour within the nets used for sampling. It shows the relative abundance of each species in a particular place and time.

We investigated the statistical relationship between the CPUE of shrimp as prey and fish as predators over the time of the studies. We call these data a ‘time series’. We ran two types of statistical analysis on these time series to look for relationships between the abundance of shrimp and the abundance of fish.

The two statistical analyses we used were Partial Least Squares Regression (PLSR) and co-integration analysis. PLSR is good for finding links between two variables (shrimp and fish) in year-to-year fluctuation, while co-integration analysis is good for slowly changing (increasing or decreasing) time series, which are called “non-stationary time series.” Most of our CPUE time series were non-stationary.

Figure 2. Scientists collected data from 6 bays along the coast of Texas, between 1986 and 2014.

Results

Figure 3: Upper Laguna Madre in the Gulf of Mexico: Relationship between White shrimp CPUEs in August and red drum CPUEs in November. (CPUE stands for catch-per-unit effort which in this case is the number of individuals of each species caught per hour within the nets used for sampling. In this graph, CPUE-s are scaled, that’s why some values are negative!)

Our PLSR analysis found 8 significant relationships between shrimp and fish time series out of a total of 36 comparisons.

Our co-integration analysis showed significant associations between 31 out of 70 shrimp and fish time series pairings.

Using co-integration analysis we also found that white shrimp in August and brown shrimp in May were strongly linked with fish CPUEs in bays on the southern coast of Texas (Fig. 3). White shrimp in November were more strongly linked with fish CPUEs in bays located to the north.

All three fish species appeared to be affected by shrimp abundance in all of the regions that we studied.

Discussion

We predicted that if our two shrimp species were vital for the fish in our study, there would be a statistical association between the changes in abundance of prey and predator.

Our PLSR analysis wasn’t conclusive because we found associations between shrimp and fish CPUEs in only 22% of cases. These associations could have just been because of statistical error.

However, our co-integration analysis showed significant associations in 52% of cases. It also revealed clear patterns between the seasons and different locations.

Different shrimp species are important at different times of the year and in different parts of the Gulf of Mexico. Observed patterns in their abundance over the latitude (the distance from the equator) might be because of changes in temperature or salinity – both of which have an effect on shrimp populations. We would need to do further studies to better understand these effects.

Fishing for all of the species in this study has had a big impact on their populations, and affected their roles as prey or predators. There have been lots of improvements in fishery management practices to stop overfishing. It is possible that these actions could be covering up, or adding to, the statistical associations that we saw.

The importance of any fishery stock is normally worked out by its market value when caught. Our research shows that the ecological importance of shrimp has been underestimated. The shrimp are not just valuable as a fishing stock, but they are also important as a forage species for three of the most valuable fishes in the Gulf of Mexico.

Conclusion

Using statistical analyses we found that there was a significant relationship between shrimp abundance and the presence of these three fish species in the Gulf of Mexico.

We also found that naturally-occurring changes in shrimp abundance from year to year complicate this relationship and additional studies are needed. However, it’s clear that shrimp fisheries need to be regulated in order to keep them sustainable. If not, it could have a negative effect on these three valuable fish species.

Glossary of Key Terms

Commercial fisheries − The people and companies who catch fish to sell them.
Habitat − The place, or type of place, where an animal lives and hangs out.
Predator − An animal that’s above another in the food web. In our study, the predators were the southern flounder, spotted
seatrout and red drum.
Prey − An animal that’s below another in the food web. In our study, the prey were the white and brown shrimp.
Recreational fishing − People who catch fish for fun and/or for their own food.
Salinity − The salt content of the sea. High salinity means there’s a lot of salt, low salinity means that there is not as much.
Significant − A result that is likely not due to chance, but rather due to a real process. Scientists often define a result as
“significant” if it would happen by chance less than 5% of the time.

Check your understanding

One of the changes in management practices was to reduce the sale of new shrimp fishing licenses and a buyback program for old licenses. Over 65% of shrimp fishing licenses were bought back and retired. What effect do you think this would have had on the shrimp population?
Most young shrimp start their lives in marshes and coastal wetlands. Our findings show the importance of protecting ecological integrity of such habitats in order to increase the amount of shrimp reaching adulthood and helping the valuable fish species they support. What management strategies would you suggest to protect these habitats?
Scientists have proven that temperature affects the survival and growth of shrimp in the Gulf of Mexico. Why do you think this is?
Why is statistical analysis alone not sufficient to prove a relationship between the abundances of shrimp
and fish? What other data can help prove a relationship?

Мore free environmental science resources аt: www.ScienceJournalForKids.org

REFERENCES
Fujiwara M, Zhou C, Acres C, Martinez-Andrade F (2016) Interaction between Penaeid Shrimp and Fish Populations in the Gulf of Mexico: Importance of Shrimp as Forage Species. PLoS One http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0166479
Alder J, Campbell B, Karpouzi V, Kaschner K, Pauly D. (2008) Forage fish: From ecosystems to markets. Annual Review of
Environment and Resources. http://www.annualreviews.org/doi/abs/10.1146/annurev.environ.33.020807.143204
EPA: About Coastal Wetlands: https://www.epa.gov/wetlands/coastal-wetlands

Acknowledgement
Publication supported in part by an Institutional Grant (NA14OAR4170102) to the Texas Sea Grant College Program from the National Sea Grant Office, National Oceanic and Atmospheric Administration, U.S. Department of Commerce. All views, opinions, findings, conclusions, and recommendations expressed in this material are those of the author(s) and do not necessarily reflect the opinions of the Texas Sea Grant College Program or the National Oceanic and Atmospheric Administration.

Aquatic ‘passenger pigeon’ shiner found swimming in the Rio Grande

21Apr

Writer: Steve Byrns, 325-653-4576, s-byrns@tamu.edu
Contact: Dr. Kevin Conway, 979-845-2620, kevin.conway@tamu.edu

COLLEGE STATION – Dr. Kevin Conway is ecstatic.

Conway, a Texas A&M AgriLife Research wildlife and fisheries scientist at College Station, is part of a joint team of researchers from Texas A&M University and Texas Parks and Wildlife Department who after years of searching, recently collected a rare fish from the Rio Grande.

“The Rio Grande Shiner, Notropis jemezanus, is a type of freshwater cyprinid fish, commonly referred to as carps, minnows and shiners, that is endemic to the Rio Grande drainage,” Conway said. “It’s large as shiners go, growing up to about 3 inches in length, and though it has never been economically valuable from a commercial or recreational standpoint, it is certainly a valuable bioindicator of river health.”

Not unlike the now extinct passenger pigeon, which was once so numerous their flights could block the sun, Conway said the Rio Grande shiner was formerly found throughout almost the entire Rio Grande drainage and was one of the most abundant species in the system. But its numbers declined steadily in both Texas and New Mexico until it became a rarity.

Rio Grande Shiner. (Texas Parks and Wildlife Department photo by Megan Bean)

“It’s not been collected in the Rio Grande in New Mexico since the 1940s and has only been collected sporadically from the lower Rio Grande along the Texas-Mexico border since 2000,” Conway said. “Its decline in Texas seems to have slipped under the radar and is likely the result of the interplay of anthropogenic manipulation of the system, including impoundment, dewatering and possibly the introduction of invasive species.”

Other contributing factors Conway alluded to were poor water quality stemming from agricultural and urban runoff and sewage effluent entering the river. Changing land management practices, including the loss of riparian gallery forests and floodplain habitats and water withdrawals, impact spring flood pulses, which serve as spawning cues for the fish, further adding to the fishes’ woes.

Those up on shiner politics might ask why some native species such as the Red Shiner are doing OK in the Rio Grande while others like the Rio Grande Shiner are not? Conway said the answer may stem from the reproductive nature of the Rio Grande Shiner.

“The Rio Grande Shiner belongs to a unique reproductive guild referred to as pelagic broadcast spawners,” he said. “Members of this guild shed eggs and sperm directly into the water column. Fertilization and development of the semi-buoyant eggs occur as they drift downstream. The eggs only take a couple of days to hatch, but in that time they can drift a long way and must remain suspended in the water column.”

Trouble comes when the streamflow slows or stops due to impoundments or too much water leaves the river during drought or times of heavy irrigation, Conway said. When the stream flow becomes too slow to move the eggs along, they sink to the bottom and become trapped in the substrate and die.

“Needless to say, these pelagic broadcast spawning shiners are among the most threatened species of freshwater fishes in the U.S., particularly in the Great Plains and desert regions of the Southwestern U.S., including Texaswhere streamflow can slow to a trickle,” Conway said. “Those like the Red Shiner continue to do well in the Rio Grande because they lay their eggs directly on the substrate where they hatch and don’t require a large stretch of river to drift in the water column.”

Conway has been conducting surveys for Rio Grande Shiner along the Texas-Mexico border since 2014 as part of a project funded by Texas Parks and Wildlife Department. Despite multiple attempts to find the fish, he had had no luck.

In a last-ditch effort in March, Conway joined forces with Megan Bean, a TPWD fish conservation biologist from Kerrville, to try to locate the species near Eagle Pass and Laredo where Bean was previously successful in finding the rare fish.

Bean said Conway’s AgriLife Research projects with the Rio Grande Shiner provide Texas Parks and Wildlife Department and conservation partners with important information on species distribution and status as well as river health. She said this information provides a data-driven, science-based approach to species conservation and management.

“We worked together to identify sites we thought would work based on earlier findings of researchers from Texas State University, University of Texas and the University of New Mexico and voucher specimens within museum collections,” Conway said.

The joint research team managed to collect four fish from the Rio Grande just downstream from Shelby Park in downtown Eagle Pass on March 21.

“This was the only spot out of six sampled by the joint agency team that produced specimens of this rare shiner,” Conway said. “But at least we are relieved to know they still exist.”

So why so much angst over a minnow?

“That’s a good question since there are lots of different silvery minnows around, so I guess you could look at this from two different points of view,” Conway said. “First, the Rio Grande shiner is probably the largest species of shiner in the U.S. and it would be a tragedy to lose it, not only because of its unique characteristics but also because there are very few pelagic broadcast spawning fishes in the U.S. in the first place. And second, the presence of a healthy number of pelagic broadcast spawners within a particular river system could be taken as a sign that the system is healthy. When they are gone then it could be taken as a sign the physical characteristics of a river have been significantly degraded. Once they are gone from a system it is not easy to put them back.”

Texas Pride is also no small reason for saving the shiner in Bean’s estimation.

“The Rio Grande Shiner is found nowhere else in the world except for this region in the U.S. and Mexico,” Bean said. “This small fish is a unique part of our natural resource heritage we should conserve, manage and treasure. It’s a part of what makes Texas so special.”

Though the future seems bleak for the Rio Grande Shiner in the lower part of the Rio Grande along the Texas-Mexico border, Conway said there may still be light at the tunnel’s end.

“We’re comparing the DNA of the four recently collected fish with that of individuals from the Pecos River in New Mexico to assess whether members of these two populations are genetically similar,” Conway said.

“The genetic investigation of the New Mexico and Texas samples of Rio Grande Shiner are being conducted by Dr. Megan Osborne at the University of New Mexico and Dr. Dave Portnoy at Texas A&M University-Corpus Christi. We are anxiously awaiting the results of these analyses in order to plan the next steps in the conservation of the Rio Grande Shiner in Texas.”

Originally appeared: https://today.agrilife.org/2017/04/21/aquatic-passenger-pigeon-shiner-found-swimming-rio-grande/

New many-toothed clingfish discovered with help of digital scans

18Apr

Credit: Kevin Conway and Glenn Moore

A set of curious researchers, state-of-the-art visual technology and a bit of good luck helped find a new fish whose tooth collection could put a shark to shame.

Scientists at the University of Washington, Texas A&M University and the Western Australian Museum have discovered and named a new genus and species of clingfish after stumbling upon a specimen preserved in a jar dating back to the 1970s. The fish was unmistakably different from the other 160 known clingfishes, named for the disc on their bellies that can summon massive sticking power in wet, slimy environments.

The researchers named the new species “duckbilled clingfish” (Nettorhamphos radula) for its broad, flat snout ? not unlike the bill of a duck ? that houses an impressive number of tiny, conical teeth.

“This fish has characteristics we just haven’t seen before in other clingfish. It’s the teeth that really gave away the fact that this is a new species,” said lead author Kevin Conway, a fish taxonomist and associate professor at Texas A&M University.

A detailed description of the new genus and species was published April 14 in the journal Copeia.

Scientists, including co-author Adam Summers of the University of Washington’s Friday Harbor Laboratories, are interested in clingfish for their ability to stick to rough surfaces. The finger-sized fish uses suction forces to hold up to 150 times its own body weight. Understanding the biomechanics of these fish could be useful in designing devices and instruments to be used in surgery, or to tag and track whales in the ocean.

Conway and co-author Glenn Moore of Western Australian Museum discovered the new clingfish while looking through specimens preserved in jars at the museum in Welshpool, Australia. It’s common for unknown specimens collected during surveys to be registered and shelved until an expert has the time, and interest, to take a closer look. This specimen was caught off the coast of Southern Australia in 1977. Even though the fish is only as big as a pinky finger, its unique teeth structure caught their attention.

A couple of hours later, Moore found yet another specimen with similar features on the museum shelves. Together, the specimens are thought to be the only two of this new species that exist out of water.

“A discovery like this highlights the importance of museum collections and reminds us just how much lies waiting to be uncovered,” Moore said. “Finding a previously unknown specimen in a jar is exciting, but our collections of identified specimens are equally important so that we have something to compare against.”

The researchers suspected they had discovered a new species that represented a new genus of clingfish, given the unusual mouth structure and teeth arrangement, but they were faced with a conundrum: Naming a new species requires an intact, complete fish with good documentation of its morphology and clear distinctions from other species. With only two known specimens, dissection was out of the question.

Instead they turned to Summers, who studies clingfish and is actively working to scan and digitize every fish species in the world using a computerized tomography (CT) scanner. Each completed scan is housed on Open Science Framework.

Using the scanner, the scientists were able to capture even finer details of the new clingfish than would be possible through manual dissection. They also used the digital scans to 3-D print parts of the fish in larger-than-life size to be able to analyze the mouth and jaw structures.

“This CT scan allowed us to take a completely noninvasive look at the entire skeleton of the fish, and it produced a gorgeous set of morphological photos that you couldn’t get from dissection,” Summers said. “It’s a testament to the importance of using these noninvasive methods of data collection.”

The scans allowed the researchers to hone in on the fish’s skeletal structure from many different angles and essentially digitally dissect parts of the fish. They estimate the tiny fish has between 1,800 to 2,300 individual teeth ? or 10 times what all other known clingfish have. The teeth point backward, which would suggest a gripping function, Conway said, but the researchers can’t be sure since the fish has never been observed in the wild.

The duckbilled clingfish joins the ranks of hundreds of new fish species that are described each year. It’s more unusual for these new species to be placed into a new genus ? in this case, the fish’s wider and longer upper jaw and abundance of tiny, dagger-like conical teeth were the sure signs of a brand-new genus.

The researchers are particularly pleased to have discovered a new clingfish in a region of Southern Australia that is known for its clingfish diversity and abundance.

“I think it’s remarkable that we would add to this diversity with yet another new genus,” Conway said. “It’s pretty special given this fauna is already pretty well-studied.”

###

This work was funded by the National Science Foundation.

For more information, contact Summers at fishguy@uw.edu or 301-864-1491; Conway at kevin.conway@tamu.edu or 979-845-2620; and Moore at glenn.moore@museum.wa.gov.au or 61-8-9212-3744 (in Australia).

Follow the #ScanAllFishes project on Twitter: https://twitter.com/hashtag/scanallfishes?lang=en

Duckbilled clingfish images: https://flic.kr/s/aHskSN9Mj3

B-roll available: https://www.dropbox.com/s/cthxo6qipok7eqv/new%20clingfish%20for%20tv.mp4?dl=0

Media Contact

Michelle Ma
mcma@uw.edu
206-543-2580
@UW

http://www.washington.edu/news/

Article from: https://scienmag.com/new-many-toothed-clingfish-discovered-with-help-of-digital-scans/

Texas A&M AgriLife helping address disease deadly to bats

3Apr

Writer: Paul Schattenberg, 210-859-5752, paschattenberg@ag.tamu.edu

Contacts: Melissa Meierhofer, 920-203-3668, mbm030@tamu.edu

Dr. Michael Morrison, 979-204-3015, mlmorrison@tamu.edu

COLLEGE STATION – The fungus that causes white-nose syndrome in hibernating bats has been detected on three species in the Texas counties of Childress, Collingsworth, Cottle, Hardeman, King and Scurry.

Bats play an important role in controlling insect populations that pose threats to Texas crops as well as assist in crop pollination. In 2011, the authors of the paper “Economic Importance of Bats in Agriculture” estimated the loss of bats to have a negative economic impact on U.S. agriculture of at least $3.7 billion annually. Recent studies indicate the value of insect control by bats to Texas agriculture is $1.4 billion annually, based on fewer crop losses from insects, reduced disease and less pesticide use.

Townsends bats (shown here) are one of the hibernating bat species in Texas testing positive for the Pseudogymnoascus destructans fugus that causes the deadly white-nose syndrome. Other bat species in the state that have tested positive for the fungus are tri-color and cave myotis bats. (Photo courtesy of Chris Taylor)

The fungus was found in samples collected by a team from Texas A&M University’s Institute of Renewable Natural Resources and wildlife and fisheries sciences department, along with Bat Conservation International. The tested samples showed the fungus was present on tri-colored, cave myotis and Townsend’s big-eared bats.

“White-nose syndrome, which is caused by the Pseudogymnoascus destructans fungus, has already caused catastrophic bat losses in the eastern U.S. and is projected to be in Texas within the next few years,” said Melissa Meierhofer, a research associate at the Institute of Renewable Natural Resources in College Station. “The disease was first reported in New York 10 years ago and has been spreading to other bat populations at a distance of about 100 miles per year.”

Texas, with 32 bat species, has the greatest bat fauna diversity in the U.S., according to the Texas Parks and Wildlife Department. To date, bats with white-nose syndrome disease symptoms have been found in 30 U.S. states and five Canadian provinces. The fungus causing the disease has been discovered in three additional states as it makes its way across North America.

Since 2011, the TPWD has worked with Bat Conservation International to monitor caves in the Panhandle for the disease. In 2015, the agency funded a statewide project with the IRNR and wildlife and fisheries sciences focused on early disease detection and identification of bat populations before white-nose syndrome appeared.

Meierhofer said the fungus had previously been discovered within the past three years in bats wintering in the neighboring states of Arkansas and Oklahoma and that it was “only a matter of time” before the fungus and disease came to Texas.

“White-nose syndrome is only known to affect hibernating bats and has no direct health impact on humans,” she said. “The cold-adapted fungus causing the disease irritates the bat’s skin, disrupting its hibernation and causing it to deplete its store of fat. And while instances of the fungus in nearby states may not have resulted in the death of the infected bat, they still demonstrated the potential for the disease to occur in Texas and the need to be vigilant.”

Meierhofer said with assistance from the TPWD, Texas Cave Management Association, Texas Speleological Survey, Texas Department of Transportation, biologists and private landowners, the team surveyed a total of 223 sites in 2016 and 2017, which included caves, buildings, culverts, bridges and even one tree site.

A tri-colored bat is swabbed for testing. (Institute of Renewable Natural Resources photo by Melissa Heierhofer)

In 2016, the team took swab samples from bats at eight cave sites in eight counties, but all samples tested negative for the fungus. In 2017, the team swabbed another 10 sites – two culverts and eight caves — in eight counties. Four of the cave sites had bats that tested positive for the fungus.

“Data from these surveys will help characterize suitable habitats where the fungus could appear so the agencies and organizations involved will be better prepared to manage the disease,” she said.

Maintaining healthy bat populations is critical, particularly for the agriculture industry, because certain bat species eat insects that can harm crops, said Dr. Michael Morrison, a professor of wildlife and fisheries sciences at Texas A&M in College Station and a co-primary investigator for the bat survey project.

“Also, without sufficient bat populations, there would be an increase in insects and that could lead to an increase in insect-vectored diseases,” Morrison said. “So accurate data on the species and populations of bats throughout the state will be helpful in protecting the bats susceptible to white-nose syndrome once it crosses into Texas.”

If the disease appears in Texas it could result in a much higher mortality for some bat species in the state, he said.

“Until we get a better handle on where the fungus and possible white-nose syndrome is located, we just cannot predict the ultimate consequences of how losing bats will affect the state’s agriculture,” Morrison said. “We’re still early in this evaluation and we just have to get out there and determine how large this problem is. That said, when the fungus arrived in other states, bats did develop white-nose syndrome and the population size of some species saw substantial declines.”

Fortunately, according to TPWD, the disease should not affect the Mexican free-tailed bat – the primary species in many popular Central Texas ecotourism sites – as this species has a short winter hibernation period.

Morrison said though there is no known cure for white-nose syndrome, numerous wildlife disease experts are actively working on treatments that may prove effective.

“There are some developing treatments for the fungus and the disease, but those will not be helpful if we cannot get a good handle on where the fungus is and how it is spreading,” he said. “Unfortunately, our current funding is not sufficient to sample as intensively as needed now that the fungus has been found in Texas.”

For more information about white-nose syndrome, go to whitenosesyndrome.org/. For more information on the institute’s efforts, go to https://www.facebook.com/texaswinterbats/.

Animal behaviorist looks through the eyes of peafowl

3Apr

Study finds beauty in the eye of the beholder…and rivalry

Writer: Steve Byrns, 325-653-4576, s-byrns@tamu.edu

Contact: Dr. Jessica Yorzinski, 979-845-5777, jyorzinski@tamu.edu

COLLEGE STATION – Flock, muster ostentation, cluster, lek, pulchritude, pride or bawl, no matter what a group of peacocks is called, Texas A&M University at College Station is now home to 40 of them, thanks to a Texas A&M AgriLife Research scientist.

Dr. Jessica Yorzinski with the university’s wildlife and fisheries sciences department, said her research flock arrived in College Station last fall and are settled in and happily enjoying Texas weather.

Yorzinski uses the birds to conduct a variety of behavioral studies. She trapped the original set from feral populations in Florida and California about eight years ago.

Dr. Jessica Yorzinski with Texas A&M University’s wildlife and fisheries sciences department studies peacocks. (Texas A&M AgriLife photo)

“I chose peafowl as study subjects because I was looking for a species in which males exhibited elaborate ornaments that females could use to assess their mates and other males could use to assess their rivals,” she said. “That was one reason, and the other reason was they are relatively large birds, so they are able to easily sport the equipment I use in my studies.”

One such study, Selective Attention in Peacocks During Assessment of Rival Males, was published in the Journal of Experimental Biology on March 15. The work and list of authors is available http://jeb.biologists.org/content/current. In the study Yorzinski looks through the eyes of the birds to actually see what the animals are paying attention to, in this particular case, how males size up their competition.

“It is important to understand how males are evaluating each other during the breeding season because their ability to compete with other males can impact their chances of copulating with females,” she said.

She found the males look at the lower regions of the other male’s display, mostly looking at the lower eyespot areas as well as the body of the rival. They also pay more attention to their rivals when said rivals are moving around or shaking their wings, but not when they are shaking their long train of decorative tail feathers. That particular movement apparently only interests the “girls.”

Yorzinski said peacocks set up territories, which they defend against rivals, and peahens visit these territories to check out potential mates.

Dr. Jessica Yorzinski with Texas A&M University’s wildlife and fisheries sciences department studies peacocks. (Texas A&M AgriLife photo)

“What we learned is that the males are evaluating similar traits when inspecting their rivals as females are evaluating when choosing their mating partners, but they are doing this, of course, for very different reasons.

“Competition among males can be costly in terms of energy expended and injuries, so males tend to spend a good amount of time, almost a third, sizing up the competition,” she said. “However, unless they are actively courting a peahen, the girls only get a glance from the males about 5 percent of the time.”

So how does one look through the eyes of a peacock? Yorzinski said that’s done through a novel approach called eye-tracking. The birds are equipped with cameras able to monitor their precise gaze behavior. The cameras were left on the birds about an hour as called for in the trial, so they didn’t have to wear the equipment continuously.

“Peafowl only mate a few months out of the year,” she said. “The males generally start displaying in early spring and continue until mid summer when they drop all their feathers and start growing a new set for the next season.

Since in the wild, being eaten by a predator is always a risk when one is distracted by too many stimuli or by a rival or prospective mate, the birds, both male and female, have likely evolved the ability to selectively shift their gaze among competing interests.

“It would be fascinating to extend this work to other species, including our own, to determine how animals are checking out their competition,” she said.

In the meantime, Yorzinski said one of the next projects she’s working on is using a system that tracks both of the birds’ eyes at the same time.

“So far, we’ve had to put a patch over one of their eyes due to technological limitations, so the next step is to look at all the visual information that the birds use and extend this current work into other contexts like navigation and foraging.”

Contact Yorzinski at 979-845-5777, jyorzinski@tamu.edu or visit her website at http://www.jessicayorzinski.com/.

INVESTIGATING AND INTEGRATING FACTORS LINKED TO SPECIES PERSISTENCE ACROSS SPACE AND TIME

31Mar

Conservation Scaling – Dr. Lee Fitzgerald

29Mar

Melting polar ice, rising sea levels not only climate change dangers

17Feb

AgriLife Researcher points to more Amazon rainforest droughts

Writer: Steve Byrns, 325-653-4576, s-byrns@tamu.edu
Contact: Dr. Kirk Winemiller, 979-862-4020, k-winemiller@tamu.edu

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.

Tambaqui, a valuable food species in Amazon fish markets, is declining due to climate change factors, said a Texas A&M AgriLife Research scientist. (Texas A&M AgriLife Research photo by Dr. Kirk Winemiller)

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/

Texas A&M institute helping find ‘key’ to preserving endangered Florida deer

15Feb

Writers: Paul Schattenberg, 210-859-5752, paschattenberg@ag.tamu.edu

Steve Byrns, 325-653-4576, s-byrns@ag.tamu.edu

Contacts: Dr. Roel Lopez, 210-277-0292, roel.lopez@ag.tamu.edu

Dr. Nova Silvy, 979-845-5749, n-silvy@tamu.edu

Dr. Israel Parker, 979-739-0679, Israel.parker@ag.tamu.edu

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.

A Key doe is captured so a radio collar can be placed for monitoring. (Institute of Renewable Natural Resources photo)

“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.

Key deer does fitted with radio collars will be monitored to find out if they or their newborn deer may be affected by screwworm flies while giving birth in the spring. (Institute of Renewable Natural Resources photo)

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.

For more information, go to http://bit.ly/2kcsaKY or http://bit.ly/2hcRtLy or contact Parker at israel.parker@ag.tamu.edu.

Exploring Yucatan cenotes

26Oct

Dr. Daniel Roelke leads an international team of scientists into the hauntingly beautiful underworld of Yucatan cenotes. The research team is exploring cenotes along a transect from Cancun to Merida, Mexico, spanning rural to urban areas in this karst landscape. The focus of the research is on relationships between cenote water quality and land-use practices. The pristine nature of this extensive aquifer is also what makes it so vulnerable to anthropogenic contaminants. The research is a collaboration between AgriLife Research at Texas A&M University and the Cancun Laboratory of Centro de Investigación Científica de Yucatán.