Constantine Alexander's Journal

New discovery: Common jellyfish is actually two species

Researchers determine that US Atlantic sea nettle and the Atlantic bay nettle are individual species.

This image shows two different jellyfish. At left is US Atlantic sea nettle (Chrysaora quinquecirrha) and at right is the Atlantic bay nettle (Chrysaora chesapeakei). Credit: Shannon Howard, South Carolina Aquarium; Keith Bayha.

University of Delaware professor Patrick Gaffney and alumnus Keith Bayha, a research associate with the Smithsonian's National Museum of Natural History, have determined that a common sea nettle jellyfish is actually two distinct species.

The Atlantic sea nettle is one of the most common and well known jellyfish along the U.S. East Coast, especially in the Chesapeake Bay and Rehoboth Bay where they commonly sting swimmers in large numbers. Since it was described nearly 175 years ago, the jellyfish has been assumed to be a single species.

The discovery that is was actually two distinct species, Gaffney said, was made possible by DNA sequencing techniques.

"Before DNA came along, people in museums looked at organisms and counted spines and bristles, measured things, and sorted organisms by their physical characteristics in order to identify species," Gaffney said. "In the case of this jellyfish, which has been commonly known for centuries, Keith found through DNA sequencing that there were actually two groups."

Turns out, the ocean-based sea nettle jellyfish is larger and has approximately 40 percent more tentacles (40, as compared to 24) than its bayside counterpart. The ocean sea nettle also has a larger bell, the top portion of the aquatic animal, while the tentacles are shorter than those in the bay nettle species.

Bayha, the paper's lead author, earned his doctoral degree in biological sciences at UD in 2005. While at UD, he worked closely with Gaffney at the Hugh R. Sharp Campus in Lewes and, during fieldwork, collected jellyfish off the Delaware coast near Cape Henlopen. Bayha's interest in the species continued well after he completed his degree, and he's collected specimens everywhere from Norway to Brazil, and studied museum specimens from the Smithsonian, where he now works.

Genetic testing of samples revealed differences in some of the sea nettle jellyfish. Working with Gaffney and Allen Collins from the National Oceanic and Atmospheric Association's National Systematics Laboratory, Bayha confirmed that there were actually two distinct species: an ocean-based species (Chrysaora quinquecirrha, "sea nettle") and a bay-based species (Chrysaora chesapeakei, "bay nettle") by comparing DNA data from the physical measurements of each species, and using statistical modeling to ask, "how good is the morphology for separating the species?"

"When you go back and pay close attention, you start counting the number of stinging cells and types, you see discrete differences that correspond to the DNA," said Gaffney. "In many cases, when we plotted the data, the graphs looked entirely different with no overlap, reaffirming that it was two species."

The newly recognized of the species is the bay nettle, which is found in less salty waters called estuaries, such as the Chesapeake Bay. NOAA produces a daily jellyfish forecast for the Chesapeake Bay, where jellyfish blooms can sometimes become a nuisance. According to Gaffney, having two distinct species may explain why efforts to understand the factors that affect a jellyfish bloom are so difficult.

The discovery also may be good news for the Eastern oyster, which is found on the Atlantic and Gulf Coasts and is the most widely consumed type of oyster. This is because bay nettle jellyfish eat harmless comb jellies called Mnemiopsis, a key predator to oyster larvae. If the bay nettles are effective at scooping up the Mnemiopsis, then the Eastern oyster larvae may have a better chance at survival.

Interestingly, the new research showed that the bay nettle seems to be closely related to jellyfish found in coastal regions of Ireland, Argentina and Africa. But according to Bayha, it's not unusual that no one took notice of these differences before.

"It's not that I did anything that different, it's just that no one else looked for a very long time," Bayha said. "Jellyfish are something people don't pay attention to because they're fleeting. They come and go, are difficulty to study, and they don't have hard parts like shells that wash up on shore."

Citation: Keith M. Bayha, Allen G. Collins and Patrick M. Gaffney; Multigene phylogeny of the scyphozoan jellyfish family Pelagiidae reveals that the common U.S. Atlantic sea nettle comprises two distinct species (Chrysaora quinquecirrha and C. chesapeakei); Peer Journal (October 13, 2017); DOI:10.7717/peerj.3863.

Contact: Peter Bothum
University of Delaware

Scientists discover most blue whales are 'right-handed' - except when they swim upward

A blue whale dives into the water of the California coast. Photo by Craig Hayslip, Oregon State University Marine Mammal Institute.

A team of scientists that used motion-sensing tags to track the movements of more than five dozen blue whales off the California coast discovered that most have a lateralization bias - in other words, they essentially are "right-handed" or "left-handed."

That didn't necessarily surprise the researchers because many animals have a right-side bias, and for good reason. In vertebrates, the left hemisphere of the brain controls coordination, predictive motor control and the ability to plan and coordinate actions - like feeding. And the left side of the brain is linked with the right eye.

However, even the "right-handed" whales become left-handed when it comes to one move, the scientists discovered. When blue whales rise from the depths to approach a krill patch near the surface, they perform 360-degree barrel rolls at a steep angle and nearly always roll to the left - even those that normally are "right-handed," according to Ari Friedlaender, a cetacean expert with the Marine Mammal Institute at Oregon State University who led the study.

"The patches of prey near the surface, between 10 and 100 feet deep, are usually smaller and less dense than prey patches found deeper and the blue whales showed a bias toward rolling left - presumably so they can keep their right eye on the prey patch and maximize their effort," said Friedlaender, who also is on the faculty of the University of California at Santa Cruz.

"These are the largest animals on the planet and feeding is an extraordinarily costly behavior that takes time, so being able to maximize the benefit of each feeding opportunity is critical. And we believe this left-sided rotation is a mechanism to help achieve that."

Results of the research, which was funded primarily by the U.S. Office of Naval Research, are being published this week in the journal Current Biology.

 

 

 

Blue whales are thought to be the largest animals to have ever lived on Earth, weighing as much as 25 elephants and reaching the length of nearly three school buses. Yet most of their diet is comprised of krill, tiny shrimp-like creatures that they filter through their mouths.

"Most of the movements we tracked that involved 'handedness' - perhaps as much as 90 percent - involved 90-degree side rolls, which is how they feed most of the time," Friedlaender said. "Blue whales approach a patch of krill and turn on their sides. We found many of them exclusively rolled to their right, fewer rolled just to their left, and the rest exhibited a combination.

"This had never been documented in blue whales before, but the left brain/right eye phenomenon is what leads to handedness in humans and tool use among apes. The most curious aspect was how so many of the whales exhibited lateralization to the left when swimming upwards at a steep angle to get prey."

That left lateralization bias is unusual in the animal kingdom, the researchers noted.

"To the best of our knowledge, this is the first example where animals show different lateralized behaviors depending on the context of the task that is being performed," said co-author James Herbert-Read of Stockholm University in Sweden.

The researchers found that the blue whales rarely performed the 360-degree barrel rolls deep in the water column, instead using that move almost exclusively at the surface. They theorize that the reason is that the whales need enough light to see the prey with their dominant right eye, thus they need to be higher in the water column.

"At the surface, a krill patch will show as a nice counter-shade to the surface light," Friedlaender said. "At 200 meters or more, the whales can't see nearly as well."

The research team collected data on more than 2,800 rolling lunges for prey by the 63 whales. The study is important because it provides new three-dimensional data on the movements and feeding behaviors of blue whales captured in their natural environment and provides insights as to how these animals are able to modify their behavior to be successful in an environment where resources are not evenly distributed.

Citation: Ari S. Friedlaender, James E. Herbert-Read,  Elliott L. Hazen, David E. Cade, John Calambokidis, Brandon L. Southall, Alison K. Stimpert and Jeremy A. Goldbogen; Context dependent lateralized feeding strategies in blue whales; Current Biology, 2017 DOI: 10.1016/j.cub.2017.10.023. 

Contact: Sean Nealon
Oregon State University

The tragedy of the seagrass commons

Indigenous fisher spearfishing in Indonesia. Credit: Swansea University.

Writing in the Journal Fish & Fisheries, Dr Richard Unsworth of Swansea University (together with colleagues at Cardiff University and Stockholm University) examine the global extent to which these meadows of underwater plants support fishing activity.

"Wherever seagrass exists in proximity to people, our research finds that it's used as a key targeted fishing habitat" said Dr Unsworth, who is based at Swansea University's Biosciences department.

"Our research is for the first time recording how globally extensive the use of seagrass meadows as a fishery habitat is. In developing countries this activity tends to have a major significance for daily food supply and general livelihoods. In developed countries the role of this activity is more for recreation or species specific targeted fisheries (e.g. clams)."

Dr Nordlund from Stockholm University added "The ecological value of seagrass meadows is irrefutable, yet there loss continues at an accelerating rate. Now there is growing evidence globally that many fisheries associated to seagrass are unrecorded, unreported and unmanaged, leading to a tragedy of the seagrass commons".

In their article, the researchers highlight that because of their nearshore, shallow water distribution in sheltered environments seagrass meadows make great places to fish in all conditions. This leads to high intensity of fishing effort often all year round.

The authors have studied seagrass fisheries all around the world from the Philippines, to Zanzibar, Indonesia, the Turks & Caicos Islands and locations in the Mediterranean. They have found many similarities in the types of fishing gear used the major animal families that are fished and the extent of effort focused in these sensitive habitats.

Even in small seagrass meadows in Wales fishers can be seen targeting shrimp at low tide and placing gill nets to catch Bass. By providing a three-dimensional structure in an otherwise barren sea, seagrasses provide the perfect hiding place for fish and invertebrates such as crabs, shrimp and clams. This abundance of animal life is what attracts fishers.

"It is important that more recognition is given to the value of these habitats for supporting fisheries as they're being damaged and degraded globally." said Dr Cullen-Unsworth (Cardiff University), one of the co-authors who is also director of the marine conservation charity Project Seagrass who are working to highlight the importance and plight of these sensitive marine habitats.

Citation: Nordlun LM, Unsworth RKF, Gullstrom M and Cullen-Unsworth LC; Global significance of seagrass fishertivity; Fish & Fisheries (17 November 2017); DOI: 101111/faf.12259.

Contact: Ffion White
Swansea University

 

Pacific Island countries could lose 50 to 80% of fish in local waters under climate change

Pacific Island nations are highly dependent on fisheries as a food source and for employment. Image by Quentin Hanich.

Many Pacific Island nations will lose 50 to 80 percent of marine species in their waters by the end of the 21st century if climate change continues unchecked, finds a new Nippon Foundation-Nereus Program study published in Marine Policy. This area of the ocean is projected to be the most severely impacted by aspects of climate change.

"Under climate change, the Pacific Islands region is projected to become warmer, less oxygenated, more acidic, and have lower production of plankton that form the base of oceanic food webs," said lead author Rebecca Asch, Nereus Program alumnus and Assistant Professor at East Carolina University. "We found that local extinction of marine species exceeded 50 percent of current biodiversity levels across many regions and at times reached levels over 80 percent."

The Pacific Islands region is the warmest of the global ocean. It's also an area where there is less seasonal variability -- it more or less feels like summer all year. Because there are no drastic seasons, the animals in the tropical Pacific may find changing conditions to be more of a shock.

"Additional warming will push ocean temperature beyond conditions that organisms have not experienced since geological time periods in this region," said co-author Gabriel Reygondeau, Nereus Fellow at UBC. "Since no organisms living in the ocean today would have time to adapt to these warmer conditions, many will either go extinct or migrate away from the western Pacific, leaving this area with much lower biodiversity."

Climate change will be strongly felt in the Pacific Islands, including impacts on fisheries, sea level rise, and extreme weather events. Image by Quentin Hanich.

The authors examined the effects of climate change on more than a thousand species, including those that live on reefs and those that live in open-water habitats. Both groups underwent declines in local biodiversity, but the rates of decline were higher for the open-water species.

These changes would be detrimental to Pacific Islanders, who are highly dependent on marine species for food, economic opportunities, and cultural heritage. Additional threats come from sea level rise and increasing major storms. Also, these are often developing countries with less resources available for societal adaptations to climate change.

"One hopeful point is that the extent of these changes in biodiversity and fisheries was dramatically reduced under a climate change scenario where greenhouse gas emissions were close to what would be needed for achieving the Paris Climate Agreement" said co-author William Cheung, Nereus Director of Science. "As a result, these changes in oceanic conditions are not inevitable, but instead depend on the immediate actions of all countries to materialize their commitment to limit greenhouse gas emissions as is being discussed in COP23 in Bonn, Germany, this week."

Citation: Rebecca G. Asch, William W.L. Cheung, Gabriel Reygondeau; Future marine ecosystem drivers, biodiversity, and fisheries maximum catch potential in Pacific Island countries and territories under climate change; Marine Policy, 2017; DOI: 10.1016/j.marpol.2017.08.015.

Contact: Lindsay Lafreniere
Nippon Foundation-Nereus Program

 

Great Barrier Reef protected zones help fish in even lightly exploited areas

Fish biomass up to five times greater compared to unprotected zones at northernmost reefs.

This is the Agincourt Reef, Great Barrier Reef, Queensland, Australia. Credit: Robert Linsdell (CC-BY).

Protected zones of the Great Barrier Reef benefit fish even at the relatively lightly-fished northern reefs, according to a study published November 8, 2017 in the open-access journal PLOS ONE by Carolina Castro-Sanguino from the University of Queensland, Australia, and colleagues.

The Australian Great Barrier Reef Marine Park is the largest network of marine reserves in the world, and includes both 'no fishing' ('no-take') and 'no-entry' zones as well as fished areas. The authors of the present study analyzed the effect of such policies in the relatively lightly-fished northernmost regions. They measured, counted and calculated the biomass of commonly-fished species found at 31 northern, central and southern reefs in the area north of Cooktown, as well as assessing the seabed habitat at these sites.

The authors found that fish biomass was up to five times greater in protected zones which prevented fishing, whether they had 'no-take' or 'no-entry' policies. The most remote northern reefs had greater fish biomass than more southern zones, regardless of the zones' policies, and the authors speculate that poaching may be common in southern reserves. They also found indication that fishers may frequently operate at reserves' boundaries to exploit the increased fish biomass in these reserves.

The specific seabed habitat of different reefs had a strong effect on the amounts and types of fish found, making it impossible for the researchers to discern any distinct effects of 'no-take' versus 'no-entry' policies. Nonetheless, they did find clear differences in biomass between protected and unprotected areas, despite this region being generally fished relatively lightly. They state that this illustrates the high sensitivity to fishing of many species, reinforcing the case for their protection.

"Even in remote reef habitats, marine reserves increase the biomass of exploited fish but detecting these benefits can be challenging because the state of corals also varies across some management zones and these patterns also affect fishes," says Castro-Sanguino. "We also conclude that fishing is most intense near reserve borders leading to a reduction of biomass just outside reserves."

Citation: Castro-Sanguino C, Bozec Y-M, Dempsey A, Samaniego BR, Lubarsky K, Andrews S, et al. (2017); Detecting conservation benefits of marine reserves on remote reefs of the northern Great Barrier Reef; PLoS ONE 12(11): e0186146;  DOI:10.1371/journal.pone.0186146.

The Khaled bin Sultan Living Oceans Foundation designed the study in consultation with PJM and implemented the collection of the data, curation and quality control of data in collaboration with the co-authors. They also funded CCS to undertake the analysis and collaborated on the preparation of the manuscript. This study was a component of the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition (2011-2015).

Contact: Beth Baker
PLOS

Climate change, sparse policies endanger right whale population

Right whale with her calf. Credit: NOAA.

North Atlantic right whales - a highly endangered species making modest population gains in the past decade - may be imperiled by warming waters and insufficient international protection, according to a new Cornell University analysis published in Global Change Biology.

North Atlantic right whales' preferred cuisine is copepods that thrive in cool waters, such as the Gulf of Maine, said author Erin Meyer-Gutbrod, who conducted the work as a doctoral student and postdoctoral researcher in the laboratory of Charles Greene, professor of oceanography and co-author on the paper.

Scientists once relied on continuous plankton sampling to track the copepods, but the National Oceanic and Atmospheric Administrations' National Marine Fisheries Service discontinued the program, preventing researchers from observing ecosystem changes as they occur.

In the past several years, a smaller portion of the right whale population has been seen in the Gulf of Maine as it has warmed, and the whales have been spotted farther north than usual, in the Canadian Gulf of St. Lawrence, likely in search of the small crustaceans, she said.

Because whales used to be rare in the Gulf of St. Lawrence, northern waterways lack whale protection policies. Without adequate policies the whales are at greater risk from ship traffic and commercial fishing gear.

"Right whales are a highly endangered species with approximately 500 animals remaining," said Meyer-Gutbrod, who now works at the Marine Science Institute at the University of California, Santa Barbara. "This crisis signals a major shift in the whale population's recovery, corresponding to a loss of 3 percent of the right whale population."

"There is a very important interaction between climate change and anthropogenic mortality factors," said Greene. "We must extend whale protections to prevent a major decline in the population."

Citation: Meyer-Gutbrod EL and Greene CH; Uncertain recovery of the North Atlantic right whale in a changing ocean; Global Change Biology (2017) 00:1-10; DOI: 10.1111/gcb.13929.

Contact: Jeff Tyson
Cornell University

 

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Turning jellyfish from a nuisance to useful product

A new 6 million euro project funded by the EU's Horizon 2020 program examines jellyfish as a commercial product.

Cotylorhiza tuberculata is sometimes called the fried egg jellyfish. Credit: Tihomir Makovec.

Global climate change and the human impact on marine ecosystems have led to dramatic decreases in the number of fish in the ocean. It has also had an unforseen side effect: because overfishing decreases the numbers of jellyfish competitors, their blooms are on the rise.

The GoJelly project, coordinated by the GEOMAR Helmholtz Centre for Ocean Research, Germany, would like to transform problematic jellyfish into a resource that can be used to produce microplastic filters, fertilizer or fish feed. The EU has just approved funding of EUR 6 million over 4 years to support the project through its Horizon 2020 programme.

Rising water temperatures, ocean acidification and overfishing seem to favor jellyfish blooms. More and more often, they appear in huge numbers that have already destroyed entire fish farms on European coasts and blocked cooling systems of power stations near the coast. A number of jellyfish species are poisonous, while some tropical species are even among the most toxic animals on earth.

"In Europe alone, the imported American comb jelly has a biomass of one billion tons. While we tend to ignore the jellyfish there must be other solutions," says Jamileh Javidpour of GEOMAR, initiator and coordinator of the GoJelly project, which is a consortium of 15 scientific institutions from eight countries led by the GEOMAR Helmholtz Centre for Ocean Research in Kiel.

The project will first entail exploring the life cycle of a number of jellyfish species. A lack of knowledge about life cycles makes it almost impossible to predict when and why a large jellyfish bloom will occur. "This is what we want to change, so that large jellyfish swarms can be caught before they reach the coasts," says Javidpour.

At the same time, the project partners will also try to answer the question of what to do with jellyfish once they have been caught. One idea is to use the jellyfish to battle another, man-made threat.

"Studies have shown that the mucus from jellyfish can bind microplastic. Therefore, we want to test whether biofilters can be produced from jellyfish. These biofilters could then be used in sewage treatment plants or in factories where microplastic is produced," the GoJelly researchers say.

Jellyfish can also be used as fertilizers for agriculture or as aquaculture feed. "Fish in fish farms are currently fed with captured wild fish, which does not reduce the problem of overfishing, but increases it. Jellyfish as feed would be much more sustainable and would protect natural fish stocks," says the GoJelly team.

Chrysaora hysoscella, also called the compass jellyfish, is common in the waters of the Atlantic and the Mediterranean. Credit: Tihomir Makovec.

Another option is using jellyfish as food for humans. "In some cultures, jellyfish are already on the menu. As long as the end product is no longer slimy, it could also gain greater general acceptance," said Javidpour. Finally yet importantly, jellyfish contain collagen, a substance very much sought after in the cosmetics industry.

Project partners from the Norwegian University of Science and Technology, led by Nicole Aberle-Malzahn, and SINTEF Ocean, led by Rachel Tiller, will analyse how physical characteristics (hydrography, temperature), biological characteristics (abundance, biomass, ecology, reproduction) and biochemical parameters (stoichiometry, food quality) affect the initiation of jellyfish blooms.

Based on a comprehensive analysis of triggering mechanisms, origin of seed populations and ecological modeling, the researchers hope to be able to make more reliable predictions on jellyfish bloom formation of specific taxa in the GoJelly target areas. This knowledge will allow sustainable harvesting of jellyfish communities from various Northern and Southern European populations.

This harvest will provide a marine biomass of unknown potential that will be explored by researchers at SINTEF Ocean, among others, to explore the possible ways to use the material.

A team from SINTEF Ocean's strategic program Clean Ocean will also work with European colleagues on developing a filter from the mucus of jellyfish that will capture microplastics from household products (which have their source in fleece sweaters, breakdown of plastic products or from cosmetics, for example) and prevent these from entering the marine ecosystem.

Finally, SINTEF Ocean will examine the socio-ecological system and games, where they will explore the potentials of an emerging international management regime for a global effort to mitigate the negative effects of microplastics in the oceans.

"Jellyfish can be used for many purposes. We see this as an opportunity to use the potential of the huge biomass drifting right in front of our front door," Javidpour said.

Contact: Nicole Aberle-Malzahn
Norwegian University of Science and Technology 

 

 

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How a 'shadow zone' traps the world's oldest ocean water

Fabien Roquet, Stockholm University.

New research from an international team has revealed why the oldest water in the ocean in the North Pacific has remained trapped in a shadow zone around 2km below the sea surface for over 1000 years.

To put it in context, the last time this water encountered the atmosphere the Goths had just invaded the Western Roman Empire. The research suggests the time the ancient water spent below the surface is a consequence of the shape of the ocean floor and its impact on vertical circulation.

"Carbon-14 dating had already told us the most ancient water lied in the deep North Pacific. But until now we had struggled to understand why the very oldest waters huddle around the depth of 2km," said lead author from the University of New South Wales, Dr Casimir de Lavergne. "What we have found is that at around 2km below the surface of the Indian and Pacific Oceans there is a 'shadow zone' with barely any vertical movement that suspends ocean water in an area for centuries.

The shadow zone is an area of almost stagnant water sitting between the rising currents caused by the rough topography and geothermal heat sources below 2.5km and the shallower wind driven currents closer to the surface. Before this research, models of deep ocean circulation did not accurately account for the constraint of the ocean floor on bottom waters. Once the researchers precisely factored it in they found the bottom water can not rise above 2.5km below the surface, leaving the region directly above isolated. While the researchers have unlocked one part of the puzzle their results also have the potential to tell us much more.

"When this isolated shadow zone traps millennia old ocean water it also traps nutrients and carbon which have a direct impact on the capacity of the ocean to modify climate over centennial time scales," said fellow author from Stockholm University, Dr Fabien Roquet.

The article Abyssal ocean overturning shaped by seafloor distribution is published in the scientific journal Nature.

Citation: de Lavergne, G. Madec, F. Roquet, R. M. Holmes & T. J. McDougall; Abyssal ocean overturning shaped by seafloor distribution; Nature 551, 181–186 (09 November 2017); DOI:10.1038/nature24472. 

Contact: Casimir de Lavergne
Stockholm University

Are cities affecting evolution?

Explosion of rats, clovers, bedbugs, mosquitoes unintended evolutionary consequence of urbanization.

In “Evolution of Life in Urban Environments,” Munshi-South and Johnson show how the study of urban evolution has been documented in cities all across the globe. In this accompanying map, blue silhouettes represent the approximate regions of origin of species that have adapted to humans since ancient times. Black silhouettes represent locations where urban evolution of species have been studied.

The recent uproar about seats on a British Airways flight crawling with bedbugs is only one of the unintended consequences that urbanization worldwide has on evolution, say Marc Johnson, an associate professor of biology at the University of Toronto Mississauga, and Jason Munshi-South, who is an associate professor of biological sciences at Fordham University.

"As we build cities, we have little understanding of how they are influencing organisms that live there," says Johnson, who is also director of the University of Toronto's Centre for Urban Environments. "It's good news that some organisms are able to adapt, such as native species that have important ecological functions in the environment. But it can also be bad news that the ability of some of these organisms to adapt to our cities might increase the transmission of disease. Bedbugs, for example, were scarce two decades ago, but they've adapted to the insecticides used to keep them at bay and have exploded in abundance worldwide."

In the first study to take a comprehensive look at the way urbanization is affecting evolution, Johnson and Munshi-South reviewed all existing research studies about urbanization and evolution and synthesized the results.

"Traditionally, we've thought about evolution as a long-term process driven by environmental pressures and the interactions between species. But now there is a new driver that is rapidly changing many other species, which is how they interact with humans and our built environment", says Munshi-South. "Humans and our cities are one of the most dominant forces of contemporary evolution now."

The study raises questions about which native species can persist during urbanization and whether those that adapt will influence the health of ecosystems and human beings. Loss of habitat and urban barriers (roads, buildings, etc.) pose challenges to all kinds of species and some may adapt in undesirable ways. The researchers assessed various means of genetic adaptation, such as mutation, the movement of genes through dispersal, neutral evolution and adaptive evolution through Darwinian natural selection, concluding that the urban environment has an impact on each of these mechanisms of evolution.

Their work touches on mammals, plants, birds, amphibians, reptiles, insects and viruses, identifying evolutionary impacts on species as diverse as the common blackbird in Europe to white clovers and white-footed mice in North America. Populations of white-footed mice in New York City, for example, became differentiated from each other after urbanization, due to their isolation in various parks.

"We've created a novel ecosystem that no organism has ever seen before," said Johnson, noting that their study, published Nov. 3 in the journal, Science, is a "wake-up call for the public, governments and other scientists."

He and Munshi-South suggest that we need to think carefully about how we're altering our environment in unintended ways when we build cities, influencing the evolution of species that may, in turn, influence our lives. A number of organisms, such as rats, urban lizards, cockroaches, pigeons and bedbugs, have evolved to depend on humans.

There are now mosquitoes, for example, that have evolved to live in the London Underground stations and adapted so that they no longer need to feed on blood to produce eggs. They also have no need to become dormant during the winter. Unfortunately, these mosquitoes can carry a number of diseases and are now found in New York City, Chicago and Los Angeles, too. Our healthcare systems may be required to adapt in response.

Johnson and Munshi-South suggest that when we're planning cities, we need to think about the impact our designs have on native species and whether we can design them to "be kinder to ourselves and the environment," considering ways to conserve native species and mitigate the prevalence of disease-carrying pests.

Given that species are evolving so rapidly in response to urbanization, the outdoors also becomes a classroom that offers an opportunity to see examples of evolution firsthand. Urban evolution can be used as a tool to educate city dwellers and others about the reality and importance of evolutionary biology.

"People who don't believe in evolution need not go further than their backyards to see evidence of it," Johnson said.

Citation: Marc T. J. Johnson & Jason Munshi-South; Evolution of life in urban environments; Science, 2017; 358 (6363): eaam8327; DOI: 10.1126/science.aam8327.

Contact: Nicolle Wahl
University of Toronto

 

A solution to fisheries overharvesting

U of G researchers have developed a model that allows fisheries to net enough to meet rising consumer demand while ensuring adequate income and replenishment of natural stocks.

There are fewer fish in the sea - literally. Consumer demand and inadequate scientific information has led to overharvesting, reducing fish species and fish stocks around the world. But University of Guelph researchers have identified a possible solution. They have developed a model that allows fisheries to net enough to meet rising consumer demand while ensuring adequate income and replenishment of natural stocks. The research was published today in Proceedings of the National Academy of Sciences.

"We know fish are getting rarer," said John Fryxell, a U of G integrative biology professor and lead author of the paper.

Many commercial fisheries are threatened by overharvesting. For example, the collapse of once-abundant cod stocks in the North Atlantic led to a federal fishing moratorium on the species in the 1990s. Managers and fisheries are hampered by a lack of information, from overall population numbers to data on how fast fish grow and reproduce. As the global population increases and demand for fish protein rises - particularly in developing countries - more fisheries are chasing smaller fish populations in hopes of recouping higher prices for their efforts. This further threatens fish stocks that are already being over-exploited, Fryxell said. Finding the "sweet spot" - where the world's fisheries can function all the while protecting natural fish stocks - was the goal of the new model.

"It gives fisheries and conservation managers a tool for balancing those competing demands," he said.

They developed the model using information about landed fish catches and prices for any species to determine by how much a given fishery has been overharvested. Basically, the model encourages fisheries to reduce short-term harvests in order to realize higher long-term yields without sacrificing economic return.

"The model is based on the premise that it's just as profitable to have high catches and low prices as high prices and lower catches," said Fryxell.

That strategy also helps ensure a more sustainable fishery over the long term, he said. Supportive policy changes might include introducing tariffs that make it less profitable to fish low-yielding, high-priced species. Or managers might encourage fish farming to provide alternative protein sources and push down prices of wild stocks, he said.

"We'd have a better world where the fishery is making money, and we're feeding more people with more fish in the ocean."

The research also connects the world's fisheries with U of G's Food From Thought project, Fryxell said.

"It's Food From Thought in a renewable rather than a managed context - how choices impact production, how we manage to make production more sustainable and still provide enough food." Co-authors are integrative biology professor Kevin McCann and other researchers at University of Guelph, McGill University, the University of Washington, and Fisheries and Oceans Canada.

Citation: John M. Fryxell, Ray Hilborn, Carling Bieg, Katrine Turgeon, Amanda Caskenette & Kevin S. McCann; Supply and demand drive a critical transition to dysfunctional fisheries; Proceedings of the National Academy of Sciences, 2017; DOI: 10.1073/pnas.1705525114.

Contact: Prof. John Fryxell
University of Guelph

 

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