Color vision found in fish that live in near darkness

MAY 9, 2019

by University of Maryland

An international team of researchers discovered a previously unknown visual system that may allow color vision in deep, dark waters where animals were presumed to be colorblind. The research appears on the cover of the May 10, 2019, issue of the journal Science.

Vertebrate eyes use two types of photoreceptor cells to see—rods and cones. Both rods and cones contain light-sensitive pigments called opsins, which absorb specific wavelengths of light and convert them into electrochemical signals that the brain interprets as color. The number and type of opsins expressed in a photoreceptor cell determine the colors an animal perceives.

"This is the first paper that examines a diverse set of fishes and finds how versatile and variable their visual systems can be," said Karen Carleton, a biology professor at the University of Maryland and co-author of the paper. "The genes that determine the spectrum of light our eyes are sensitive to turn out to be a much more variable set of genes, causing greater visual system evolution much more quickly than we anticipated."

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Study of Arctic fishes reveals the birth of a gene—from 'junk'

February 11, 2019, University of Illinois at Urbana-Champaign

Though separated by a world of ocean, and unrelated to each other, two fish groups—one in the Arctic, the other in the Antarctic—share a surprising survival strategy: They both have evolved the ability to produce the same special brand of antifreeze protein in their tissues. A new study describes in molecular detail how the Arctic fishes built the gene for their antifreeze from tiny fragments of noncoding DNA, regions once considered "junk DNA."

The findings are reported in the Proceedings of the National Academy of Sciences.

"Years ago, we discovered how antifreeze glycoproteins evolved in Antarctic notothenioid fishes, and we knew that the Arctic cod evolved an identical version—but not in the same way," said University of Illinois animal biology professor Christina Cheng, who led the new study with graduate student Xuan Zhuang. "But exactly how the codfish independently did it has remained a lasting puzzle."

To solve that puzzle, Cheng and her colleagues scoured fish and other vertebrate genomes for a gene that might have been the ancestral precursor to the codfish antifreeze gene. They came up empty, so they decided to compare the genomes of codfish that did and did not produce antifreeze protein to see how the two lineages differed. The researchers found the ancestor of the antifreeze gene in a region of noncoding DNA, which, as its name implies, does not code for a viable protein.

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Tons of dead fish wash up in Rio de Janeiro lagoon

December 21, 2018

Dead fish float in the Rodrigo de Freitas lagoon in Rio de Janeiro, Brazil, Friday, Dec. 21, 2018. About 21 tons of fish died in the Rio de Janeiro lagoon, while city authorities and biologists argue about the cause of the die-off. (AP Photo/Silvia Izquierdo)

Residents of a high-end neighborhood in Rio de Janeiro woke up to the unpleasant smell of 13 tons of rotting dead fish floating in the city's Rodrigo de Freitas lagoon.

Biologists believe that the extreme heat caused by El Nino killed the fish overnight and caused them to wash ashore Friday.

The lagoon played host to several events during the 2016 Olympic games and is a tourist attraction.

Rio's environment ministry released a statement saying that it has been on alert since Thursday morning when oxygen levels in the body of water began to fall sharply.

Biologist and ecosystem specialist Mario Moscatelli says that he inspects the lagoon every year and is convinced that climate change is causing temperature increases.

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'Sick to my stomach': dolphin and penguins locked in derelict Japan aquarium

Anger after hundreds of fish and reptiles have been left in tiny pools amid crumbling concrete since January

Justin McCurry in Tokyo

Fri 31 Aug 2018 02.12 BSTLast modified on Sat 1 Sep 2018 03.12 BST

Anger is mounting in Japan after a dolphin, 46 penguins and hundreds of fish were found to have been abandoned for months in a derelict aquarium.

Animal rights campaigners have warned that the marine animals could die if they are not rescued from the Inubosaki marine park aquarium in the Pacific coastal town of Choshi north-east of Tokyo.

The plight of Honey, a female bottlenose dolphin, as well as scores of Humboldt penguins and hundreds of fish and reptiles, has triggered outrage following reports that they were abandoned when the facility closed seven months ago.

Images taken from outside the marine park in March this year show the solitary dolphin languishing in a tiny pool. In another photograph, dishevelled-looking penguins can be seen perched on a structure near what appear to be piles of loose concrete.

The marine park closed at the end of January following a dramatic drop in visitor numbers blamed on the earthquake and tsunami that struck Japan’s north-east in March 2011.

Reports said employees of the marine park were feeding the animals, although it is unclear how they are sourcing food and how much they have left. It is possible that the park still has large stocks of frozen food or that employees are purchasing fresh fish in Choshi, a fishing port.

Animal rights campaigners have been refused entry to the facility, while local authorities have been unable to contact its private owner, Inubosaki Marine Park. Calls to the park’s owner went unanswered.

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Acidic oceans cause fish to lose their sense of smell

July 23, 2018, University of Exeter

When carbon dioxide is absorbed by seawater carbonic acid is formed, making the water more acidic. Since the Industrial Revolution, oceanic CO2 has risen by 43% and is predicted to be two and a half times current levels by the end of this century.

Fish use their sense of smell (olfaction) to find food, safe habitats, avoid predators, recognize each other and find suitable spawning grounds. A reduction in their ability to smell therefore can compromise these essential functions for their survival.

The new study provides evidence that economically important species will be affected by elevated CO2, leaving fish vulnerable because it affects their ability to detect odours.

University of Exeter researcher Dr. Cosima Porteus, who led the study, said: "Our study is the first to examine the impact of rising carbon dioxidein the ocean on the olfactory system of fish. First we compared the behaviour of juvenile sea bass at CO2 levels typical of today's ocean conditions, and those predicted for the end of the century. Sea bass in acidic waters swam less and were less likely to respond when they encountered the smell of a predator. These fish were also more likely to "freeze" indicating anxiety."

Experts at the University of Exeter, in collaboration with scientists from the Centre of Marine Sciences (CCMar, Faro, Portugal) and the Centre for Environment, Fisheries and Aquaculture Science (Cefas), also tested the ability of the sea bass' nose to detect different smells. They did this by recording the activity in the nervous system while their nose was exposed to water with different levels of CO2 and acidity.

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The origins of those sexual organs: a fishy tale much more primitive than we thought

July 19, 2018 by John Long And Marion Chevrinais, The Conversation

Euphanerops, a primitive jawless fish from the World Heritage site at Miguasha, Quebec, which has now been found to have paired hind limb structures and copulatory sex organs. Credit: François Miville-Deschênes with permission, Author provided

Fossil discoveries from the Devonian rocks of Scotland and Australia first revealed that the earliest jawed fishes, the placoderms, reproduced using copulation in much the same way as sharks and rays do today.

They also had the first paired pelvic skeletons, the precursor to the hind paired fins – and legs – of all animals. Their paired reproductive organs, called "claspers", probably developed in the same way as limbs.

The appearance of jaws and teeth in the first vertebrates was thus intimately linked to the origin of paired hind limbs (pelvic girdles) and an advanced kind of sexual reproduction.

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Hippo Poop Is Literally Suffocating Fish

By Mindy Weisberger, Senior Writer | May 17, 2018 07:40am ET

On a savanna in southwestern Kenya, thousands of hippos converge daily along a stretch of the Mara River, gathering in groups among dozens of shallow pools, where they sink into the water to protect their sensitive skin from the sun.

But they aren't there just to cool down — they also come to poop.

As the hippos wallow, they collectively expel considerable quantities of waste — an estimated 9.3 tons (8,500 kilograms) of excrement each day, scientists recently reported. Large animals' feces nourish ecosystems by providing vital nutrients for smaller organisms, but the sheer volume of hippopotamus dung poses a deadly challenge to fish that live downstream from these communal toilets, leaving the fish gasping for oxygen under a deluge of dissolved hippo poo, according to a new study. [How Much of the Ocean Is Whale Pee (and Worse)?]

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25 years of fossil collecting yields clearest picture of extinct 12-foot aquatic predator

May 7, 2018 by Frank Otto, Drexel University

After 25 years of collecting fossils at a Pennsylvania site, scientists at the Academy of Natural Sciences of Drexel University now have a much better picture of an ancient, extinct 12-foot fish and the world in which it lived.

Although Hyneria lindae was initially described in 1968, it was done without a lot of fossil material to go on. But since the mid-1990s, dedicated volunteers, students, and paleontologists digging at the Red Hill site in northern Pennsylvania's Clinton County have turned up more - and better quality - fossils of the fish's skeleton that have led to new insights.

Academy researchers Ted Daeschler, PhD, and Jason Downs, PhD, who specialize in the Devonian time period (a time before dinosaurs and even land animals) when Hyneria lived, have been able to reconstruct that the predator had a blunt, wide snout, reached 10-12 feet in length, had small eyes and featured a sensory system that allowed it to hunt prey by feeling pressure waves around it.

"Dr. Keith Thomson, the man who first described Hyneria in 1968, did not have enough fossil material to reconstruct the anatomy that we have now been able to document with more extensive collections," explained Daeschler, curator of Vertebrate Zoology at the Academy, as well as a professor in Drexel's College of Arts and Sciences.

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Fish accounted for surprisingly large part of the Stone Age diet

Date:  March 19, 2018

Source:  Lund University

New research at Lund University in Sweden can now show what Stone Age people actually ate in southern Scandinavia 10 000 years ago. The importance of fish in the diet has proven to be greater than expected. So, if you want to follow a Paleo diet -- you should quite simply eat a lot of fish.

Osteologists Adam Boethius and Torbjörn Ahlström have studied the importance of various protein sources in the human diet across three millennia, from around 10 500 to 7 500 years ago. This was done by combining chemical analyses of human bones from over 80 individuals, whose skeletons are the oldest discovered in Scandinavia, with osteological analyses of animal bone material.

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High levels of microplastics found in Northwest Atlantic fish

New study finds microplastics in the stomachs of 73 percent of mesopelagic fish caught in the Northwest Atlantic -- one of the highest levels globally

Date:  February 16, 2018

Source:  Frontiers

Summary:

A new study finds 73 percent of mesopelagic fish caught in the Northwest Atlantic had microplastics in their stomachs -- one of the highest levels globally. Typically living at depths of 200-1,000 meters, these fish could spread microplastic pollution throughout the marine ecosystem, by carrying microplastics from the surface down to deeper waters. They are also prey for fish eaten by humans, meaning that microplastics could indirectly contaminate our food supply.

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What do piranhas and goldfish have in common?

Date:  November 3, 2017

Source:  Louisiana State University

Summary:

Researchers including some of the biggest names in ichthyology from universities and museums across the US and Mexico used highly conserved regions of animal genomes, called ultraconserved elements (UCEs), to compile one of the most data-rich phylogenies of fishes to date. Here's what they found.

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Snapper family ties provide new evidence on marine reserves

October 18, 2017 by Anne Beston

A higher proportion of young snapper in fishing areas north of Auckland are related to adult snapper from the Goat Island Marine Reserve, confirming what scientists have long suspected: the reserve acts as a giant snapper nursery.

The new study from the University of Auckland's Institute of Marine Science is the first time scientists have studied a temperate commercial fishing species to find evidence of a direct parental link between adults in a marine protected area to juveniles outside.

Led by Professor John Montgomery, Dr Shane Lavery, and former University of Auckland postdoctoral fellow Dr Agnès Le Port, the research team used a combination of genetic testing and hydrodynamic modelling of snapper larvae.

They found at least 11 percent of juvenile snapper up to 40km away were the offspring of spawning adults from the reserve at Leigh north of Auckland, whereas no offspring matches were found to adult snapper sampled from non-reserve areas.

"The contribution from the reserve is about 10 times higher than would be expected if snapper larval contribution was simply proportional to geographic area," Professor Montgomery says.

An area of 400 square kilometres was included in the study, from Mangawhai in the north to Mahurangi in the south. Goat Island Marine Reserve makes up just 1.3 percent of the area studied. It is a 'no take' marine reserve meaning fishing is strictly prohibited.

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Fish shrinking as ocean temperatures rise

Date:  October 4, 2017

Source:           Louisiana State University

Summary:

One of the most economically important fish is shrinking in body weight, length and overall physical size as ocean temperatures rise, according to new research by LSU Boyd Professor R. Eugene Turner published today. The average body size of Menhaden -- a small, silver fish -- caught off the coasts from Maine to Texas -- has shrunk by about 15 percent over the past 65 years.

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Plenty of fish in the sea? Not necessarily, as history shows

October 4, 2017 by Anna Clark, The Conversation

Australia has had tens of thousands of years of fisheries exploitation. That history reveals a staggering natural bounty, which has been alarmingly fragile without proper management. The current debate over the federal government's new draft marine park plans is the latest chapter of this story.

Early accounts described what we can only read today as some sort of fishing Eden. The sea floor off the west coast of Tasmania was carpeted red with crayfish. Extraordinary schools of Australian salmon swelled the beaches of southern Australia—from Albany right around to Port Macquarie. Mountains of mullet migrated annually up the east coast of the continent.

Colonial writers described huge hauls of fish, caught using nets they had brought over on the First Fleet. One catch in 1788 was so large, wrote David Collins, the colony's newly minted Judge-Advocate, that it actually broke the net. Collins speculated that if the haul had been landed, the entire catch could "have served the settlement [of over 1000] for a day".

Like colonial fishers on the coast, inland explorers such as John Oxley were struck by the paradox of Australia's natural world. The land seemed barren and unsuited for pastoralism, he observed in 1817, yet the water teemed with life. In less than an hour, one of his party "caught 18 large fish, one of which was a curiosity from its immense size and the beauty of its colours," wrote Oxley. "It weighed entire 70 pounds [31kg]."

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Cloudy with a Chance of Seafood? Fish Fall from Sky in Mexico

By Sara G. Miller, Staff Writer | October 2, 2017 11:45am ET

The weather forecast for the coastal city of Tampico, Mexico, on Sept. 28 may have called for light rain; instead, it got light rain with a side of fish.

Yes, fish fell from the sky in the northeastern Mexican city, in the southeastern part of the Tamaulipas state, during a light rain, The Associated Press reported last week. Tamaulipas state officials posted photos of four small fish that dropped to the ground during the rain shower.

But can the skies actually rain fish? Turns out, they can. Scientists believe that fish — or other small aquatic animals — can get sucked up from oceans or lakes by waterspouts during a storm. (Waterspouts are tornadoes that touch on water.) Then, strong winds carry the critters inland before dropping them down on unsuspecting people.

Fishy rains have been documented around the world, from California to India to England. 

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There are hardly any old fish left in the ocean – and that’s bad

15 September 2017

By Michael Tennesen

There are not just fewer fish in the sea: there are disproportionately fewer old fish. A study of fisheries in the seas around the US and Europe has found that their populations of ageing fish have been reduced by an average of 72 per cent.

The researchers looked at 63 fisheries, which had records spanning 24-140 years. To determine the age of fish, they used several techniques including examining otoliths: “stones” in the fish’s ears that grow annual rings rather like a tree.

“The new statistics revealed that the reduction of older fish populations had actually increased by 180 per cent,” says lead author Lewis Barnett of the University of Washington in Seattle.

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Male fish mutating into females because of waste chemicals, expert warns

Expert calls for stronger stance on chemicals and drugs that are likely to have ‘sub-lethal’ effects on wildlife

Ian Johnston Environment Correspondent

Monday 3 July 2017 13:00 BST

Tougher controls should be considered on chemicals that can feminise male fish and cause other “sub-lethal” effects, a leading ecotoxicologist has said.

Nearly 10 years after he helped reveal how significant an impact human drugs were having on wildlife, Professor Charles Tyler has warned that scientists are becoming increasingly concerned about the consequences of thousands of waste substances.

Some are from industrial processes, but others are drugs taken by people that then pass through them and into the sewers or are simply flushed directly into the toilet.

Professor Tyler, of Exeter University, will talk about the issue in a speech at the 50th Anniversary Symposium of the Fisheries Society in the British Isles.

He took part in a major study in 2008 that found nearly a quarter of male roach fish taken from 51 sites on English rivers showed signs of becoming female, such as having eggs in their testicles.

In some rivers, all the male roach were found to have been feminised to a degree because of high levels of oestrogen, which is used along with progestin in birth-control pills to prevent ovulation and is also present in other drugs.

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Fossil holds new insights into how fish evolved onto land

June 21, 2017

"It's like a snake on the outside, but a fish on the inside."

The fossil of an early snake-like animal - called Lethiscus stocki - has kept its evolutionary secrets for the last 340-million years.

Now, an international team of researchers, led by the University of Calgary, has revealed new insights into the ancient Scottish fossil that dramatically challenge our understanding of the early evolution of tetrapods, or four-limbed animals with backbones.

Their findings have just been published in the prestigious international research journal Nature."It forces a radical rethink of what evolution was capable of among the first tetrapods," said project lead Jason Anderson, a paleontologist and Professor at the University of Calgary Faculty of Veterinary Medicine (UCVM).

Before this study, ancient tetrapods—the ancestors of humans and other modern-day vertebrates - were thought to have evolved very slowly from fish to animals with limbs.

"We used to think that the fin-to-limb transition was a slow evolution to becoming gradually less fish like," he said. "But Lethiscus shows immediate, and dramatic, evolutionary experimentation. The lineage shrunk in size, and lost limbs almost immediately after they first evolved. It's like a snake on the outside but a fish on the inside."

Lethicus' secrets revealed with 3D medical imaging

Using micro-computer tomography (CT) scanners and advanced computing software, Anderson and study lead author Jason Pardo, a doctoral student supervised by Anderson, got a close look at the internal anatomy of the fossilized Lethiscus. After reconstructing CT scans its entire skull was revealed, with extraordinary results.

"The anatomy didn't fit with our expectations," explains Pardo. "Many body structures didn't make sense in the context of amphibian or reptile anatomy." But the anatomy did make sense when it was compared to early fish.

"We could see the entirety of the skull. We could see where the brain was, the inner ear cavities. It was all extremely fish-like," explains Pardo, outlining anatomy that's common in fish but unknown in tetrapods except in the very first. The anatomy of the paddlefish, a modern fish with many primitive features, became a model for certain aspects of Lethiscus' anatomy.

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Distant fish relatives share looks

June 15, 2017 

James Cook University scientists have found evidence that even distantly related Australian fish species have evolved to look and act like each other, which confirms a central tenet of evolutionary theory. 

Dr Aaron Davis from the Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) at JCU said the phenomenon, known as convergent evolution, happens when different fish adopt similar lifestyles and evolve through time to look very similar.

Scientists used techniques such as scanning electron microscopy and x-ray imaging to investigate species' bodies and feeding mechanisms.

"The study highlighted some really striking similarities in characteristics like tooth and jaw structure and body shape between Australian freshwater grunters and several other marine fish families when they share feeding habits," said Dr Davis.

Convergent evolution is one of the fundamental predictions of evolutionary theory. The JCU research was published in the prestigious Proceedings of the Royal Society B journal (and highlighted on the Proceedings of the National Academy of Sciences website).

It identified significant convergence in body form between Australian freshwater terapontid grunters and several distantly related marine fish families separated by 30-50 million years of evolution.

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