New Pacific marine parks


This video says about itself:

9 October 2017

Two countries have made a big new splash in ocean conservation. Niue, a tiny island in the South Pacific, has committed to protecting 49,000 square miles of ocean, including one of the world’s best habitats for reef sharks. Additionally, Chile will create two new reserves totaling 240,000 square miles. Both countries will restrict fishing in the new marine protected areas. All three reserves were scientifically supported by National Geographic Society’s Pristine Seas program.

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Female fish like singing males


This 2012 video from Germany is called Common Gobies (Pomatoschistus microps) in narrow channels around the island of Juist.

From the University of Gothenburg in Sweden:

Female fish like males who sing

October 4, 2017

Noisier seas seem to hamper fish reproduction. A new doctoral thesis from the University of Gothenburg shows that noise pollution impedes reproduction in sand and common gobies, both of which are important food sources for juvenile cod.

Underwater noise is invisible. It is also inaudible above the surface. It travels almost five times faster than in air, and also over much longer distances.

‘We can record the noise of boats that are far out of sight, and the sound is basically unchanged. It can be likened to living in Gothenburg and hearing the sound of all the cars driving around in Stockholm. That would be very noisy and would probably not be permitted, since it would be considered a health hazard. However, this does not apply to our seas, since there are no clear noise regulations for that environment,’ says Eva-Lotta Blom, author of the doctoral thesis, which explores how underwater noise affects reproduction in sand and common gobies (Pomatoschistus minutus and Pomatoschistus microps, respectively).

Increasing Noise Pollution in the Seas

The discovery that fish communicate with sounds is relatively new, and it remains unclear how and why the sounds are used and how they are interpreted by the receivers.

But in order for a male sand or common goby to be able to reproduce, it seems to be necessary for him to make himself heard.

‘So against the background of the rapidly growing use of leisure boats and other sources of noise in the marine environment, it is important to understand how fish are affected by noise.’

Males Attract Females by Singing

Sand and common gobies live in shallow waters along the entire Swedish coastline. Both species are fairly small (4-9 cm) and constitute an important food source for cod.

During its slightly more than 1-year long lifespan, the male will nest in an empty clamshell or in a hole he has dug. Then he will try to attract females to join him by showing off what he has to offer.

‘If a female comes over to inspect his nest, the male is able to produce a sound that is critical to the female’s decision of whether or not to mate with him. The sand goby sounds like a purring cat while the smaller common goby sounds more like an intense woodpecker.’

Females Choose Good Singers

If the female decides that the male is a suitable candidate for mating after listening to his singing, she will spawn in his nest. Then she will leave the male to take care of the eggs by himself until they hatch. This means that females will only select males who sing. Something in the male’s singing seems to determine whether or not she will select him as a partner.

‘The sound may contain some type of information, but if this is the case, we have no idea what the information might mean. What we do know, however, is that the singing is critical to the male’s reproductive success.’

But what happens if the female cannot hear the male’s singing because of too much noise in the water? To examine the possible negative effect of underwater noise, the fish were exposed to a sound source in their aquarium. The transmitted sound was in the same frequency range as the sound of a leisure boat.

‘So we created a realistic scenario for the fish. Then we let two females and one male interact freely for 12 hours and looked at what happened. What we found was remarkable.’

Noise Interfered with Reproduction

The researchers found that fish that interacted in a noise environment hardly mated at all. And if they did, it took them much longer than fish that interacted in a silent aquarium.

In addition, half of the eggs in the noisy aquariums died before hatching. And if they did hatch, it took longer than the eggs in the silent environment.

‘The studies also show that when you do experiments involving fish, the environment needs to be as quiet as possible, or else the results may be affected by noise. If some aquariums in a study have been more exposed to noise than others, this has to be taken into account when assessing the findings,’ says Blom.

Link to the article: here.

African penguins pack hunting of fish, video


This New Scientist video says about itself:

African penguins hunt fish in packs

27 September 2017

Cameras strapped to African penguins reveal that the birds team up to hunt shoals of fish. Read more here.

Sharks, rays live longer than estimated before


THis 2014 video from the USA says about itself:

Stingrays and Manta rays come in many shapes and sizes… But one of the coolest rays in all the ocean has to be the giant Shark Ray.

In the front they are broad like a ray, but the back section they are all shark with dual dorsal fins. How cool is that! Also known as a bowmouth guitarfish, this large species can reach a length of 2.7 m (8.9 ft) and weigh up to 135 kg (298 lb).

WHERE TO SEE RAY SHARKS IN THE USA In one of the biggest resorts in town, there’s a major Aquarium with full grown Shark Rays in it. It’s called the “Shark Reef” and it’s main tank is filled with 1.3 million gallons of water. This Aquarium displays all kinds of sharks, rays, fish, reptiles, even a green sawtooth shark — but the real celebrities here are the Shark Rays….

Just step inside what they call the Shark Tunnel and within seconds you will have a very up close and personal encounter – guaranteed!

SHARK RAYS ARE A THREATENED SPECIES Shark Rays are not dangerous to humans. They like to eat crabs or lobsters and stuff like that but their numbers in the wild are dwindling due to overfishing. They are killed for the shark fin on top. It’s the main ingredient in Shark Fin Soup which is popular in certain parts of the world. Attempts to breed these amazing creatures in captivity so far has been a failure. Seven pups born at the Newport Aquarium in Kentucky all died within a few months of their birth.

From James Cook University in Australia:

Sharks and rays live a lot longer than we thought

September 29, 2017

A James Cook University researcher has found that sharks and rays live a lot longer than we thought — some twice as long as previously estimated.

Dr Alastair Harry looked at 53 different populations of sharks and rays that scientists had already intensely studied. He said in nearly a third of populations the studies had underestimated the animals’ ages.

“Questions arose over methods of ageing sharks after it was found that grey nurse sharks can live up to 40-years-old, double the length of time first thought, and the age of New Zealand porbeagle sharks had been underestimated by an average of 22 years,” he said.

Dr Harry said scientists usually measure shark age by counting growth rings in their vertebrae. These measurements are confirmed by tagging animals and injecting them with a fluorescent marker or by measuring carbon accumulated in the animals from atmospheric testing of nuclear weapons in the 1950s.

“Age underestimation appears to happen because the growth rings cease to form or become unreliable beyond a certain size or age. Across the cases I studied age was underestimated by an average of 18 years, and up to 34 years in one instance. From the amount of evidence we now have it looks like the problem is systemic rather than just a few isolated cases,” he said.

Dr Harry said accurate age estimation was important because it was used to manage fishery stocks.

He said the underestimation of longevity in orange roughy, a deep-sea fish, led to overly optimistic estimates of stock productivity, contributing to serious, long-term ecological and socio-economic impacts.

Dr Harry said sharks and rays are less commonly targeted by commercial fishers, but are still often caught as bycatch. That means the impacts of age underestimation may well take longer to become apparent.

“It could lead to inefficient prioritisation of research, monitoring and management measures. If it’s as widespread and common as it seems from this study, the impacts could also be substantial from a wider scientific perspective, affecting the many disciplines that also use baseline life history data,” he said.

How zebrafish get their stripes


This video from the USA says about itself:

6 November 2014

In the clip, a 10-day-old zebrafish gets its stripes in this series of images taken one a day for 30 days. Credit required: D Parichy Lab/University of Washington.

From Cardiff University in Wales:

How do zebrafish develop their stripes?

Cardiff University mathematician discovers key aspect underlining distinctive patterns of the zebrafish

September 28, 2017

A Cardiff University mathematician has thrown new light on the longstanding mystery of how zebrafish develop the distinctive striped patterns on their skin.

In a new study, Dr Thomas Woolley has simulated the intricate process that sees the pigmented skin cells of the zebrafish engaged in a game of cat and mouse as they chase after each in the early developmental stages before resting to create a final pattern.

Dr Woolley discovered that a key factor is the angles at which the cells chase after each other, and these angles can determine whether a zebrafish develops its distinctive stripes, broken stripes, polka-dot patterns or sometimes no pattern at all.

The findings have been presented in the journal Physical Review E.

Rather than have a pattern ingrained in their genetic code, zebrafish start their lives as transparent embryos before developing iconic patterns over time as they grow into adults. As is often the case in nature, many possible mutations exist and this can dictate the pattern that develops in the zebrafish.

Several researchers have studied how and why these pattern form and have concluded that it’s a result of three types of pigment cells interacting with one other. More specifically, black pigment cells (melanophores), yellow pigment cells (xanthophores) and silvery pigment cells (iridophores), chase after each other until a final pattern is reached.

As hundreds of these chases play out, the yellow cells eventually push the black cells into a position to form a distinct pattern.

Dr Woolley, from Cardiff University’s School of Mathematics, said: “Experimentalists have demonstrated that when these two types of cells are placed in a petri dish, they appear to chase after each other, a bit like pacman chasing the ghosts. However, rather than chase each other in straight lines, they appear to be chasing each other in a spiral.

“My new research has shown that the angle at which the cells chase after each other is crucial to determining the final pattern that we see on different types of zebrafish.”

In his study, Dr Woolley performed a number of computer simulations that took a broad view of how cells move and interact when the zebrafish is just a few weeks old. Different patterns were then spontaneously generated depending on the chasing rules.

By experimenting with different chasing angles in his simulations, Dr Woolley was able to successfully recreate the different patterns that are exhibited by zebrafish.

Trinidadian guppies have individual personalities, new research


This 2014 video says about itself:

Sustainable Innovation Initiatives (SII) creates bridges between research, business, industry, tourism and educators to make ecological sustainability a priority for societies in tropical forest ecosystems. Our upcoming documentary series helps us accomplish this goal by reaching many people through video.

“Home of the Guppy” is our first episode. It highlights unique features of research in the Northern Range of Trinidad and grassroots efforts in habitats critical to this watershed and communities that use it.

Home of the Guppy Summary: Streams in Trinidad’s Northern Mountain range have been epicenters for breakthroughs in evolutionary theory over the last five decades.

A unique combination of isolation, species-diversity and system-replication has created a “natural laboratory” like no other in the world. These unique conditions have allowed scientists to examine every guppy in multiple wild populations for as many as 15 generations. Guppy studies in Trinidad have produced one of the most detailed multi-generation data collections ever compiled in a wild vertebrate. Results from these studies are reshaping longstanding views of evolutionary theory.

From the University of Exeter in England:

Fish have surprisingly complex personalities

Tiny fish called Trinidadian guppies have individual ‘personalities,’ new research shows

September 25, 2017

Scientists from the University of Exeter studied how guppies behaved in various situations, and found complex differences between individuals.

The researchers tested whether differences could be measured on a “simple spectrum” of how risk-averse or risk-prone guppies were. But they found variations between individuals were too complicated to be described in this way.

“The idea of a simple spectrum is often put forward to explain the behaviour of individuals in species such as the Trinidadian guppy,” said Dr Tom Houslay, of the Centre for Ecology and Conservation (CEC) on the University of Exeter’s Penryn Campus in Cornwall.

“But our research shows that the reality is much more complex. “For example, when placed into an unfamiliar environment, we found guppies have various strategies for coping with this stressful situation — many attempt to hide, others try to escape, some explore cautiously, and so on.

“The differences between them were consistent over time and in different situations. So, while the behaviour of all the guppies changed depending on the situation — for example, all becoming more cautious in more stressful situations — the relative differences between individuals remained intact.”

The study, published in the journal Functional Ecology, examined the “coping styles” of guppies in conditions designed to cause varying levels of stress.

Mild stress was caused by transferring fish individually to an unfamiliar tank, and higher levels of stress were caused by adding models of predatory birds or fish.

The presence of predators had an effect on “average” behaviour — making all of the guppies more cautious overall — but individuals still retained their distinct personalities.

Professor Alastair Wilson, also from the CEC at the University of Exeter, added: “We are interested in why these various personalities exist, and the next phase of our research will look at the genetics underlying personality and associated traits.

“We want to know how personality relates to other facets of life, and to what extent this is driven by genetic — rather than environmental — influences.

“The goal is really gaining insight into evolutionary processes, how different behavioural strategies might persist as species evolve.”

The paper is entitled: “Testing the stability of behavioural coping style across stress contexts in the Trinidadian guppy.”

When evolving in environments where a lack of predators makes food scarcity the main survival challenge, guppy mothers gestate their young longer so that they are born more ready to compete for their meals: here.

Fish evolution, new discovery


Fukangichthys

By Viviane Callier, 2:17pm, September 18, 2017:

3-D scans of fossils suggest new fish family tree

Analysis of specimens from China implies ray-finned fishes are younger than previously thought

When it comes to some oddball fish, looks can be deceiving.

Polypterus, today found only in Africa, and its close kin have generally been considered some of the most primitive ray-finned fishes alive, thanks in part to skeletal features that resemble those on some ancient fish. Now a new analysis of fish fossils of an early polypterid relative called Fukangichthys [from the Triassic] unearthed in China suggests that those features aren’t so old. The finding shakes up the evolutionary tree of ray-finned fishes, making the group as a whole about 20 million to 40 million years younger than thought, researchers propose online August 30 in Nature.

Ray-finned fishes named for the spines, or rays, that support their fins — are the largest group of vertebrates, making up about half of all backboned animals. They include 30,000 living species, such as gars, bowfins and salmon. The group was thought to originate about 385 million years ago, in the Devonian Period. But the new research, using 3-D CT scans of the previously discovered fossils, shifts the fishes’ apparent origin to the start of the Carboniferous Period some 360 million years ago, says study coauthor Matt Friedman, a paleontologist at the University of Michigan in Ann Arbor.

One of the largest extinction events in Earth’s history marks the boundary between the Devonian and Carboniferous. “We know that many groups of backboned animals were hard hit by the event,” Friedman says. But after the massive die-off, ray-finned fishes popped up and, according to previous fossil evidence, their diversity exploded. The new finding “brings the origin of the modern ray-finned fish group in line with this conspicuous pattern that we see in the fossil record,” Friedman says. It suggests these vertebrates didn’t survive the event. They came after, then flourished.