Zebrafish see well, new study

Posted on June 22, 2018 by petrel41

This 2017 video is called Eyes of Zebra fish may help unveil cure for human blindness, say scientists.

From the University of Sussex in England:

Zebrafish‘s near 360 degree UV-vision knocks stripes off Google Street View

June 21, 2018

Summary: A zebrafish view of the world has been forensically analyzed by researchers to reveal that how they see their surroundings changes hugely depending on what direction they are looking.

Tiny freshwater fish have a view of the world that blows Google Street View out of the water — using different parts of their eyes to deliver optimum uses of colour, black-and-white and ultraviolet.

A zebrafish view of the world has been forensically analysed by researchers at the University of Sussex to reveal that how they see their surroundings changes hugely depending on what direction they are looking.

The study of the colour vision system of zebrafish larvae, published today in Current Biology, reveals they use their near 360 degree view of their world to detect threatening silhouettes above them in black-and-white but can seek out the almost transparent single-cell organisms they feed on by detecting the scattering of light in UV.

Dr Tom Baden, a senior lecturer in neuroscience at the University of Sussex who led the research, said: “By measuring the activity of thousands of neurons in the live animal while presenting visual stimuli, we established that different parts of their retinas, looking at different parts of the visual world, do different things. This multi-faceted view makes perfect sense for zebrafish as that’s how colour is distributed in their natural habitat. In their natural visual world, most colour information is on the ground and the horizon but above them the objects of most interest are dark silhouettes, so colour vision here is rather pointless.”

The study is the first in-depth physiological description of any vertebrate’s retinal setup for colour vision that uses “4 input colours” which includes a large proportion of non-mammal species such as most birds, reptiles, amphibians and fish. By comparison humans only use three and mice, dogs and horses only two.

The researchers say little is understood on how colour vision based on four or more spectral inputs works at a neuronal level but their paper, should help pave the way for further discoveries in this field. The team custom-built a hyperspectral scanner that allowed them to capture the full spectrum of light in the zebrafish natural world at each pixel including for UV vision.

The study found that zebrafish, who during larval and juvenile life stages live mostly in shallow, low current pockets on the sides of streams and rice paddies, only seem to use their colour vision repertoire for looking down and along the horizon, use colour-blind circuits for looking straight up and extremely sensitive ultraviolet vision for looking forward and upwards.

The zebrafish has made a supreme evolutionary effort to develop this superior vision, with about half of all its neurons inside the eyes making up nearly a quarter of their total body volume and requiring substantial metabolic investment. Similar ratios on a human being would mean eyes around the size of a large grapefruit which would require an optic nerve the width of an arm.

Dr Baden said: “Clearly, animals like zebrafish use specialised strategies to better navigate their natural environment by adjusting their eyes to look out for different things in different parts of their visual field. In contrast, technology has not really caught up with these types of ideas. For example, most standard camera systems still “blindly” use the same type of light detection and compression across an entire image even if half the image shows bright blue sky and the other half the overgrown and shadowed ground.”

Why zebrafish (almost) always have stripes. Mathematical model helps explain key role of one pigment cell: here.

Researchers used zebrafish to study the effects of knocking out three clock genes, Cry1a, Cry2a, and Per2. They compared wild-type zebrafish with those with single, double, or triple knockout of these genes under conditions of complete darkness, three hours of light, and finally 12 hours of light reflecting typical daylight. The team revealed reduced locomotion and more resting associated with gene knockout, linking this to impaired metabolism: here.

It is already known that zebrafish can flexibly regenerate their hearts after injury. An international research group now shows that certain heart muscle cells play a central role in this process. The insights gained could be used to initiate a similar repair process in the human heart: here.

Save sea trout in England

Posted on January 5, 2017 by petrel41

This video says about itself:

14 December 2009

Three sea trout spawning in December 2009 on a small stream tributary of the Sussex Ouse. There are two larger fish in the redd spawning (a male and a female up to about 8lb) and also a smaller chancer male about 40cm downstream of them. When the larger male is not so active the smaller one darts in and tries to fertilise the female’s eggs, and is then usually seen off by the larger male.

By Dave Bangs in England:

Another native species under threat

Thursday 5th January 2017

Sussex’s native sea trout have returned to Britain’s freshwater rivers and streams since before the last ice age, yet their habitats are being destroyed, writes DAVE BANGS

FOR ME, there is only one native British fish more beautiful than the Atlantic salmon, and that’s the sea trout of the Sussex race.

I should explain that the sea trout is a particular type of our native trout species which leaves its birthplace in our little streams to roam the sea before returning to its natal stream to spawn.

Many of its close relatives choose to stay all their lives at home, however, and they are known as the brown trout or “brownies.”

They tend to be much smaller because their freshwater diet is poorer than a sea-going diet.

Our Sussex sea trout can be as big as salmon and spawn later than other races of their kind.

You find their gravel nests around Christmas time, especially in our chalk streams.

At deepest dusk, if you are lucky, you may see a giant “hen” fish lying in the scrape she has dug, whilst the “cock” fish sidle up to her to mix their milt (sperm) with her roe (eggs).

Their backs emerge from the shallow riffles like surfacing submarines, whilst the water breaks over them.

In their breeding finery they are spotted brightest pink and black and grow to 2.5ft long and over 12lb in weight.

These fish have probably been returning annually to our local rivers from their rich sea feeding waters since long before the end of the ice age some 12,000 years ago.

Their migrations have marked the retreat of glaciers and tundra and the greening of our 30-mile wide Wealden vale to the lush “salad bowl” of trees and meadows that it is today.

Things are not good for these ancient beasts, however, whose numbers may be counted nowadays in the hundreds rather than the teeming thousands of the deep past.

Obstructing weirs have been built along most streams to facilitate farmers’ irrigation and commercial navigation, to make mill ponds, and manage coarse fisheries.

Sewage works and farmers’ pollutions periodically plague the rivers.

As the human population of the south east of England swells in response to capitalism’s unequal regional development new housing requires more and more freshwater, and the head streams shrivel and dry back towards the Rivers Adur and Ouse main channels.

Only the perennial springs along the base of the South Downs scarp give certainty of flow to the crystal clear chalk streams.

There is however no certainty about the future of those streams either.

This year a “posh food” business sought to bring another rare species — Siberian sturgeon — to the meadows next to a sea trout nursery stream of the Ouse, to stock the newly dug ponds of a “caviar farm” (caviar is sturgeon eggs) bringing new risks to the precious water supply of these streams, breaking the open riparian corridor and threatening new biosecurity measures and exclusion fences.

The residents who led the campaign against the fish farm were a cross section of our modern countryside: rich bankers and business millionaires.

Their campaign slogan: “Wrong Fish, Wrong Place,” attracted sarcastic responses from those urban folk who felt the sturgeon farmer was not the only person whose entitlement to this countryside they wished to challenge.

We won that time, despite the social narrowness of the campaign and Lewes district council rejected the fish farm’s planning application.

Yet within a few days, far worse disaster struck.

At dead of night a system failure at the dairy unit of nearby Plumpton Agricultural College emptied the contents, it is estimated, of a whole slurry tank into the headwaters of the Plumpton Mill Stream.

A kilometre-long “slug” of ink-black dung and urine rolled down into the Bevern stream and along to the confluence with the River Ouse at Barcombe Mills.

Every brown and sea trout in its path and every other fish — minnow, stone loach, bullhead, eel, chub and the only known breeding colony of brook lamprey in these streams — were suffocated.

In one night, the streams which the Ouse and Adur Rivers Trust had been working to conserve for 30 years were stripped of their higher life forms.

It may take another generation to restore them.

This is not the first time Plumpton College has polluted our streams. Anglers and river workers report pollution incidents back as far as they can remember: nine incidents just since 2011.

Day and night, the workers of the Environment Agency struggled to contain the pollution with sandbags, oxygenators and water pumps.

But the damage had been done.

Will the magnificent beasts of these little streams survive beyond our time?

That is up to us. It is not up to millionaire rural residents and businesses. It is not up to polluting private rural colleges.

It is up to us — from our towns and cities — to reclaim and restore our natural heritage.

USA: A multi-institutional team of researchers has assessed how environmental, demographic, and genetic factors play a role in the reintroduction of bull trout in Washington State: here.

Save wildlife in Sussex, England

Posted on November 30, 2016 by petrel41

This video from England says about itself:

4 November 2014

From rolling hills to bustling market towns, the South Downs National Park’s landscapes cover 1,600km2 of breathtaking views and hidden gems. A rich tapestry of wildlife, landscapes, tranquillity and visitor attractions, weave together a story of people and place in harmony.

From the Hampshire Hangars to the iconic white cliffs of the Sussex Heritage Coast, from curvaceous hills, rolling farmland, ancient woodland and lowland heaths, to our ‘picture perfect’ villages, traditional country pubs and flourishing vineyards – the South Downs National Park will subtly seduce you.

To celebrate and show our support for World Responsible Tourism Day on November 5th 2014, we have launched this new video showing the beauty of the South Downs National Park.

A new guide making it easier to choose responsible holidays in the South Downs is available from Our Land – the only site exclusively dedicated to promoting tourism in protected landscapes in the UK. The guide contains a wealth of practical, interesting, fun and quirky information in an easy to read and easily digestible format. Everything you need to know to discover, enjoy and care for South Downs National Park including amazing accommodation that suits you, how to enjoy your visit without using a car and tourism businesses that put landscape at the heart of everything they do.

Visit http://www.southdowns.gov.uk/DiscoverEnjoyCare to find out more.

By Dave Bangs in Britain:

It’s up to us to stop the South Downs sell-off

Wednesday 30th November 2016

Selling off the last of Sussex’s council-owned downlands with its rare flora and fauna would be a tragedy, writes DAVE BANGS

IN THE past months major storms have arisen on the Sussex Downs due to threatened large-scale sales of local council-owned downland. On the Brighton Downs the city council has been “reviewing” its “non-core assets” and attempting to dispose of a series of sites.

These include part of a 50-year-old nature reserve which is the last county site for the little native Juniper conifer (present on the Downs since the Ice Age); a cave with four resident species of bat and the iconic Plumpton Hill, with its commanding views over the forested Sussex Weald.

On the Eastbourne Downs behind Beachy Head, the council has been moving towards the disposal of over 3,000 acres of public downland, which form the backdrop to the town. It includes numerous prehistoric burial mounds and field systems, a neolithic hill fort and large, nationally important wildlife sites for orchids and rare flowers such as the Moon Carrot, which glows white in the darkest night.

On these Downs, the local councils are major landowners, having acquired large tranches of land cheaply in the 1920s, ’30s and ’40s during the long agricultural depression. They did so to protect them from rapidly expanding urban sprawl, to protect the chalk aquifer — the source of their drinking water — and to protect the ancient open sheep walks, beloved by walkers and naturalists. While they largely failed with the latter objective (because agribusiness farmers ploughed up much archaic grassland that was tractor-accessible), they succeeded with the two former objectives.

The legacy of these conservation purchases is huge. Brighton Council owns some 12,500 acres; Eastbourne Council has 4,200 acres; Worthing Council has 500 acres; East Sussex County Council has about 700 acres at Seven Sisters and Lewes and Adur Councils have several hundred acres between them.

This 18,000 acres — plus the public downland — forms the backbone of public assets within the new South Downs National Park, together with the Forestry Commission’s estates. The National Park Authority itself owns no land; it doesn’t even own a public toilet.

Tragically, the loss of the open sheep walks (depriving the public of traditional access) and the commercial management of the estates by arms-length land agencies like Savills and Strutt and Parker have meant that the cultural memory of these free and open landscapes has been much eroded.

Twenty years ago, Brighton’s Labour-led council tried to sell its downland, but was forced to abandon the proposal by a vigorous campaign. Five years ago, the Tory-controlled Worthing Council abandoned similar sales proposals in the face of militant opposition. Both councils then “came good” and designated huge tranches of their downland as statutory “freedom to roam” land. Major changes in downland management brought in much wildlife and heritage conservation and partially recreated the great sheep walks which gave the South Downs its character.

In some areas, such as behind Beachy Head, this amounted to superb measures of finely crafted landscape restoration.

This was just what the late Michael Meacher, former Labour environment minister, had in mind when he announced the creation of a South Downs National Park and proposed it would be dedicated to the restoration of a landscape which had lost over 90 per cent of its archaic grasslands.

Within the last two months, activists in Brighton and Eastbourne have launched Keep Our Downs Public (KODP) campaigns. In Brighton we have secured a temporary halt on the sales and the policy will be reviewed on December 8 at the key council committee.

There we face the current opposition of the Labour leadership (though the sales policy was initiated in 2014 under the Green Party leadership) but we are hopeful that this can be reversed. In Eastbourne we face the opposition of the Lib Dem leadership. However, the new KODP group organised a feisty 120-strong town hall picket and a lively semi-public meeting with the council leader within its first fortnight. Activists face the task of helping the council recover the lost memories of its progressive past.

If we lose the Duke of Devonshire Estates, the old property developers who built Eastbourne will have a legal right to first refusal on much of the sold land. Rich new owners may exclude us, damage vulnerable wildlife habitat, turn the farms over to game shoots and excluding land uses (like vineyards, solar arrays, private “parks” and horticulture) with their CCTV cameras and high fences and press for incremental built developments.

If we win, we can drive forward more huge gains in public access (over 2,000 acres of new access land already around Brighton) and stitch back together the historic landscape’s shattered tapestry of archaic wildflower grassland in a sustainable pastoral economy.

Across the country, similar battles are being fought in defence of public land, parks, open spaces and county council smallholdings.

First ever dinosaur’s brain found on English beach

Posted on October 28, 2016 by petrel41

This video says about itself:

First Ever Dinosaur Brain Has Been Found In The UK

27 October 2016

A brown pebble found in Sussex 10 years ago is actually the fossilised brain of a dinosaur thought to have lived 133 million years ago, scientists have revealed.

It is the first time anyone has seen what a dinosaur brain looked like as no other fossils have been found.

And the researchers said the discovery raised the tantalising prospect that the creature, believed to be a species similar to an Iguanodon, may have had an unexpectedly large brain.

Stop killing badgers, march in Brighton, England

Posted on February 16, 2016 by petrel41

Stop killing badgers

This poster announces a march against the killing of badgers in England on 27 February, in Brighton.

See more here.

More Dutch birds information on the Internet

Unusual butterfly behaviour in England

Posted on August 7, 2015 by petrel41

From the Sussex Wildlife Trust in England, about this video:

Frisky Fritillary

05 August 2015

This silver-washed fritillary and meadow brown were filmed in Hoe Wood at Woods Mill nature reserve by Reserve Manager, Steve Tillman. You can see the strange behavior of the silver-washed fritillary as it takes a persistent interest in the meadow brown. The fritillary followed the meadow brown around the woodland. This carried on for at least five minutes.

We asked our butterfly expert, Michael Blencowe, what he thought about the behaviour. Michael said “I think that it is likely that the silver-washed fritillary is trying to mate with the meadow brown. It is possible that something about the meadow brown – the orange on the wings perhaps – is acting as a trigger to the silver washed fritillary. Inter-species copulation is rare -but by no means unknown. I’ve seen this behaviour before between meadow browns and ringlets and even small tortoiseshells and meadow browns. However this pairing is new to me.”

Birds singing in England

Posted on April 17, 2015 by petrel41

This video from Britain says about itself:

Getting to grips with warblers 4: Whitethroat Vs Lesser Whitethroat

In the fourth of our series of videos aimed at helping with the tricky task of identifying warblers, we take a look at Whitethroat and Lesser Whitethroat. BirdTrack reports show that May is a good time to catch up with them. So it’s a good time to brush up on the songs and ID features of these two common species.

By Graeme Lyons, in Sussex, England, on Twitter today:

Cetti’s Warbler, Whitethroat, Lesser Whitethroat all singing at Woods Mill right now!

Injured mute swan saved in England

Posted on January 12, 2015 by petrel41

This video from Britain says about itself:

Lewes Swan Rescue and Release 23rd and 24th April 2013

24 April 2013

Teamwork leads to rescue and release of swan caught in fishing line at Lewes.

Worried residents contacted East Sussex Wildlife Rescue & Ambulance Service (WRAS) after spotting a swan on the River Ouse at Lewes with fishing line hanging out of its mouth and attached to fishing weights.

Rescuers attended on site on Monday 22nd but were unable to catch the swan from the bank, so asked British Divers Marine Life Rescue (BDMLR) if they would help provide a boat for the rescue. As the tide was low, the charities planned a rescue for the morning of Tuesday 23rd April. Overnight the weights came loose and disappeared, but it was clear from the swan’s behaviour that there was something wrong.

Alan Knight OBE chairman of BDMLR launched their rescue RIB with the assistance of Medic Gavin Bruce from Newhaven just after 9am and came up to Lewes where it was met by WRAS’s Trevor Weeks MBE and fellow rescuers Jayden Banks and Kathy Martyn. Alan manoeuvred the rescue boat with skill with Trevor positioned at the bow using a swan hook to gently guide the swan between the bank and the pontoons at Lewes Rowing Club where Kathy and Jayden were positioned to catch the swan.

This was Jayden’s first swan rescue and found himself catching the swan using a swan hook and having to pull the swan up onto the pontoon where it was secured. Kathy, Trevor and Gavin quickly joined Jayden on the pontoon.

Trevor checked over the swan and found a piece of line wrapped round the back of the mouth and going down the throat. As it was right at the back of the mouth it was difficult to get to but was eventually dislodged but the swan swallowed the line before it could be removed safely.

The swan was noted to be very pale and a bit underweight and was transported to WRAS’s Casualty Care Centre at Whitesmith where it was given 24 hours rescue and recuperation before being returned to Lewes the following day Wednesday 24th April.

The swan recovered well overnight and was much more lively, and energetic. Clearly recovered the swan was taken back to the rowing club and released to be back with her mate on the river.

“This is a great example of how groups can work together in a positive way to help each other and the wildlife of East Sussex, BDMLR have specialist knowledge and equipment for such water based rescued and we would have struggled to catch the swan without their help” said Trevor Weeks, “when we released the swan back into the river it was nice to see the pair back together and them flirting with each other forming the classic heart shape with their necks. It’s great to see.”

From Wildlife Extra, this January 2015:

Dramatic swan rescue on the Pevensey Levels

Three men and two ambulances were recently involved in a dramatic rescue of an injured Mute Swan that had been spotted completely covered in blood.

The East Sussex Wildlife Rescue & Ambulance Service (WRAS) in the shape of Trevor Weeks MBE of Uckfield, Chris Riddington of Eastbourne, and Tony Neads of Polegate, rushed to the scene and found the swan in a field just west of the road between the village of Wartling and Pevensey Service Station.

“I’ve never seen anything quite like it” says Riddington. “The swan was completely red, there were no white feathers at all, just blood everywhere.”

Unfortunately, the rescue effort were hampered by flooding across the field. On the first attempt at capture the swan managed to take off.

“We were really surprised that the swan flew but as it was so windy it really didn’t take much more than opening it wings in order to take off” ssys Weeks.

“The swan landed in a drainage dyke at the far side of the field. To get to there we had one large dyke and three smaller dykes to cross.

“The first three channels which are normally dry during the summer were about knee deep in water.

“When I got close to the swan it was in an awkward place for me to get to, but an ideal place to try capture.

“There was only one thing for it and that was to take my jacket and fleece off and swim across the dyke.”

“From the other side of the field we couldn’t believe what Trevor was doing,” says Riddington.

“All of a sudden he just disappeared into the water and then reappeared as he climbed out again – we just thought ‘he’s nuts!’ and its freezing!”

The rescue plan worked and Weeks was able to catch the swan successfully.

“I was a bit worried about how I was going to get the swan back across the dyke, but with some help from Chris, the swan was safely moved across the dyke and back to WRAS’s ambulances,” says Weeks.

“Trevor was soaking wet from head to toe, and clearly very cold too,” says third rescuer Neads.

“So after bedding the swan down in the ambulance and providing first aid, we wrapped Trevor in blankets and both were driven back to WRAS’s Casualty Centre for treatment.”

Back at WRAS’s Casualty Centre the swan was checked over and found to have numerous deep cuts one of which was a venus bleed.

“We had to apply a trauma gauze to the lower beak to help stop the bleeding which had to be taped in place, says Weeks. “After seeking advice from the Swan Sanctuaries Veterinary Team we decided to send the swan up to their specialist vets to assess. But we hope it will be suitable for returning to the area once fit and well.”

Save English tawny owls from speeding cars

Posted on September 18, 2014 by petrel41

This video is called An Introduction to the Tawny Owl (Strix aluco).

From Wildlife Extra:

Tawny owls casualties of speeding cars

East Sussex Wildlife Rescue & Ambulance Service (WRAS) is warning drivers in East Sussex to slow down when driving at night following a spate of collisions with tawny owls.

A total of ten tawny owls were hit over a six-week period at Ashdown Forest, Uckfield, Scaynes Hill, Magham Down, Hastings, Lewes, Polegate, and Eastbourne.

“Unfortunately three died out on site before our emergency ambulances arrived,” said WRAS Casualty Centre Manager and Director Kathy Martyn, “three had to be put down due to the severity of their injuries, two have been released and two are still in care.”

The incidents all happened at night or at dusk, when the owls are active, hunting on the roads for rodents in grass verges and roadside embankments. “Many people think it’s safe to drive fast at night as you can see approaching car’s head lights from a distance,” said Trevor Weeks, MBE founder of East Sussex WRAS, “sadly wildlife don’t have lights on them and could easily run out into the road causing potentially fatal injuries to both the animal as well as humans.”

WRAS is seeking to reduce the number of casualties by urging drivers to think about animals that could be crossing roads when driving in the dark.

Tawny owls are common and found throughout the UK, but they remain protected under the Wildlife and Countryside Act. Once mated, males and females often stay together for life, and will seldom leave their territory.

Stoats on Texel island

Posted on August 14, 2014 by petrel41

This video from England says about itself:

Mad Stoat – Crazy dance

A Stoat at Pulborough Brooks, West Sussex doing the ‘mad dance’. It’s thought that they do this to confuse prey, but they just seem to have amazing fun.

Just watch him go!

Texel is the only island in the Dutch Wadden sea where stoats live, local Ecomare museum reports.

They are the biggest carnivorous mammal of the island.

They feed mainly on voles.