The World's Most Trusted Source of Information About the Fascinating World of Fish keeping

Jump to Site Navigation


You are currently browsing the TFH Extras category.

New Colonial Marine Organisms Discovered in Madeira

Favosipora purpura

Favosipora purpurea, one of the new species of bryozoans discovered on the island of Madeira.
Credit: Javier Souto et al.

The Portuguese island of Madeira is considered a diversity hotspot for bryozoans, which are colonial, principally marine, organisms. However, the fauna of these small animals only started being documented a short while ago. A team of Spanish and Portuguese scientists have now discovered two new species of bryozoans, as well as another that had previously only been found in the waters of Rio de Janeiro (Brazil).

To date, some 140 species of bryozoans have been identified in Madeira, which is why some authors consider the island to be a diversity hotspot for the zoological group. However, most of the knowledge they have of the region’s animals is from studies carried out by English researchers at the end of the 19th and beginning of the 20th centuries.

Over the last few years, the application of more modern study techniques, together with electron microscopy, has enabled the diversity of these organisms to be analysed in greater detail, meaning greater distinctions between species can be made. This technology, in the majority of cases, allows researchers to compare the material collected now with what was gathered previously.

Thanks to these new methods, scientists from various Spanish and Portuguese centres have analysed samples of rocks colonised by the organisms at a depth of 11 metres, which were collected from the south of the island in August 2013. The results, published in the journal Zootaxa, reveal the discovery of two new species: Favosipora purpurea and Rhynchozoon papuliferum.

“This study not only describes two species of bryozoans which are new to science, but six documented species from the island of Madeira and a species considered endemic to Brazil which was found outside those waters for the first time are also described again,” Javier Souto, a researcher affiliated with the University of Vienna and the department of Zoology and Biological Anthropology of the University of Santiago de Compostela (USC), said.

In order to draw these conclusions, the team studied material gathered by the researchers themselves and samples collected at the end of the 19th century held in the Manchester Museum (UK). “In doing this we were able to confirm that all this material corresponded to a species that had never been discovered before, which we named Rhynchozoon papuliferum,” said Souto.

According to the biologist, the name is related to the papilla-esque morphology of avicularians (zooids that are specialists in defence), “a fact that British scientist A. W. Waters (who gives his name to the collection of bryozoans in the English museum) had noticed as early as 1909, but the characteristic did not lead him to discover a new species,” explained the Spanish researcher.

However, Favosipora purpurea, which takes its name from the colour of its colonies, is the first species belonging to this genus to be observed in the Atlantic Ocean, and it had previously only been known to inhabit the Pacific and Indian Oceans. As for its characteristics, it is more or less circular with a two-centimetre diameter.

Rediscovering the bryozoans

“The bryozoans are one of the most important fouling organisms of the marine benthos and often go unnoticed because of their small size,” underlined the author. Around 6,000 species are currently known around the world, but the actual figure is believed to be in the region of 11,000.

These animals form colonies that range from a few millimetres to large colonies almost a metre in size and they can consist of a mere few zooids right up to thousands of them, with morphologies and functions within the group varying from one species to another.

“This morphological variation is what distinguishes one species from another. In order to observe this variation, a scanning electron microscope, which enables accurate identification, is required,” noted Souto. The study also enabled six previously recorded species to be re-observed on the Portuguese island, with the technology providing new data and images of said species.

The study was carried out within the framework of a species monitoring project whose objective is to recognise diversity and detect species introduced by human activity on the island of Madeira. The initiative was started in 2013 by Joao Canning Clode, a researcher at, among other centres, the Marine Biology Station of Funchal (Maderia).

Story Source: Plataforma SINC

Originally published here:  www.sciencedaily.com/releases/2015/05/150519083546.htm

Posted May 20th, 2015.

Add a comment

Deadly Sponges Snuffing-Out Coral Colonies

dnews-files-2015-04-sponge-smothering-coral-150427-jpg[1]

Brain coral (Diploria labyrinthiformis) overgrown and smothered by the lavender branching sponge Aplysina cauliformis.

Joseph Pawlik, UNCW

It sounds like the plot of a B-movie, but researchers have determined that sponges in over-fished areas are using deadly tactics — such as smothering and toxic mucus — to kill coral colonies so that the sponges can grow on what’s left: skeletons.

The discovery shows how disruption of even just a few members of an ecosystem — in this case, tasty fish — can hurt many other organisms that live in the same area.

The problem, highlighted in the latest issue of the journal PeerJ, is particularly evident at Caribbean coral reefs, where the combined effects of warming seawater temperatures, storms, and diseases have already decimated populations of corals.

While coral looks sort of like an undersea plant, groupings actually consist of tiny marine creatures that live together within compact colonies. They usually grow slowly. Sponges, on the other hand, grow either quickly or more slowly, depending on the species.

“If the goal is to save the corals that build Caribbean reefs, we have to protect the angelfishes and parrotfishes that eat sponges,” lead author Tse-Lynn Loh, now a Postdoctoral Research Associate at the Haerther Center for Conservation and Research at Chicago’s Shedd Aquarium, said in a press release.

Loh and colleagues surveyed reefs from 12 countries across the Caribbean. The scientists compared 25 sites where fish abundance is very low (because of decades of intensive fish trapping) with 44 sites where fishes are plentiful (because they’ve been protected from fishermen).

Both fast and slow-growing sponges tended to dominate coral colonies at overfished sites, adversely impacting at least 25 percent of them. The damage was more than double the incidence of this seen at less-fished reefs. At the latter, angelfishes and parrotfishes munched on the sponges, helping to keep their dominant ways in check.

Even when the fish were around, slower-growing sponges still made a dent in coral colonies, since these sponges can unleash their arsenal of “weapons” that allow them to compete aggressively for reef real estate. In addition to the smothering tactics and toxic mucus, the sponges can kill coral by releasing other toxins and by shading out light.

In past studies, seaweed was also found to hurt coral, but the new research led to the surprising discovery that seaweeds were more abundant on reefs with greater numbers of fish. The outcome is contrary to the conventional wisdom that fishes eat seaweeds and keep them in check. It now looks like the relationship between seaweeds and fishes is more complicated than previously imagined.

Conservationists in earlier years based some of their claims about needed regulation of fishing at reefs on the idea that fish kept damaging seaweed under control. Now, there is convincing evidence that sponges, and perhaps not so much seaweed, are heavily impacted by over-fishing, which sets the stage for the sponges to kill and take over coral reefs.

“Caribbean nations can now base their fishing policy decisions on the clear connection between overfishing and sponge-smothered corals,” said co-author Joseph Pawlik of the University of North Carolina at Wilmington. “Coral conservation requires a healthy population of reef fishes.”

Author: Jennifer Viegas

Originally published here: http://news.discovery.com/earth/oceans/deadly-sponges-are-snuffing-out-coral-colonies-150427.htm

Posted May 18th, 2015.

Add a comment

First In Fish: ‘Fully Warm-Blooded’ Moonfish Prowls The Deep Seas

NOAA Fisheries biologist Nick Wegner holds an opah caught during a research survey off the California coast. Researchers say the opah is the first fish known to be fully warm-blooded, circulating heated blood throughout its body.

NOAA Fisheries biologist Nick Wegner holds an opah caught during a research survey off the California coast. Researchers say the opah is the first fish known to be fully warm-blooded, circulating heated blood throughout its body.

Over decades of studying the oceans’ fishes, some species have been found to have partial warm-bloodedness. But scientists say the opah, or moonfish, circulates heated blood — and puts it to a competitive advantage.

“Nature has a way of surprising us with clever strategies where you least expect them,” according to NOAA Fisheries biologist Nicholas Wegner, who works in the Southwest Fisheries Science Center in La Jolla, Calif. In a news release about finding, Wegner said, “It’s hard to stay warm when you’re surrounded by cold water but the opah has figured it out.”

The opah is not a small animal; it’s roughly the size of a car tire and often weighs more than 100 pounds. In the past, it was often viewed as a fairly complacent dweller of water that’s hundreds of feet deep.

Now researchers say the opah also uses internal warmth to help it move quickly and efficiently — and kill prey such as squids and smaller fish. As the researchers describe in the journal Science, the fish relies on an internal heating system that seems to have been developed in frigid waters.

From the National Oceanic and Atmospheric Administration Fisheries:

“Satellite tracking showed opah spend most of their time at depths of 150 to 1,300 feet, without regularly surfacing. Their higher body temperature should increase their muscle output and capacity, boost their eye and brain function and help them resist the effects of cold on the heart and other organs, Wegner said.

“Fatty tissue surrounds the gills, heart and muscle tissue where the opah generates much of its internal heat, insulating them from the frigid water.”

Heat is generated from the opah’s large wing-like pectoral fins, which were previously thought only to help it swim fast enough to catch prey.

The agency’s researchers say they found an unexpected design tweak in the opah’s gills that sets it apart from other fish: a counter-current heat exchange in which blood vessels carrying warm blood are twined around vessels that are bringing oxygen — and cold temperatures — from the gills. The design helps the opah maintain endothermy (warm-bloodedness).

“The fish had an average muscle temperature about 5 degrees C (roughly 9 degrees Fahrenheit) above the surrounding water while swimming about 150 to 1,000 feet below the surface,” NOAA says.

Revelations about the opah’s blood temperature come after a moonfish was captured in a striking photograph off the California coast earlier this year, an encounter that was seen as part of a surge in opah sightings off the western U.S. coast.

Opah have more commonly been spotted in Hawaii — including at fish auctions.

Of the flavor, National Geographic has reported:

“Opah are unusual in that different parts of their body look and taste different, the biologist explains. The upper part of the fish looks like tuna and tastes like a cross between tuna and salmon, he says. But their pectoral muscles — the ones that power the fins on the side of the body — look and taste a bit like beef.”

Originally published here: http://www.npr.org/sections/thetwo-way/2015/05/15/407072979/first-in-fish-fully-warm-blooded-moonfish-prowls-the-deep-seas

Author: Bill Chappell

Posted May 18th, 2015.

Add a comment

Cichlid Fish Display Extensive Social Interactions

150507114048_1_900x600[1]

Neolamprologus pulcher (N. pulcher) is the breed of cichlid used in the study.

Credit: Dario Josi

A new study shows that cichlid fish reared in larger social groups from birth display a greater and more extensive range of social interactions, which continues into the later life of the fish. Researchers say this indicates the fish develop more attuned social behavior as a result of early environments.

The researchers also found that those fish raised in a more complex social environment have a different brain structure to those who experienced fewer group members in early life. If fish experienced the complex social environment for 2 month they had a larger hypothalamus: the area that contains most of the brain nodes of the ‘social behavior network’. They also had a larger ‘optic tectum’, which processes visual stimuli and could be related to the need to process more visual stimuli in larger groups, say researchers.

The brains of fish with enhanced social skills were not bigger overall than those reared in small groups; however, the ‘architecture’ within the brain was different.

“Our data suggests that, during development, relative brain parts change their size in response to environmental cues without affecting overall brain size: increasing certain parts forces others to decrease concurrently. These ‘plastic’ adjustments of brain architecture were still present long after the early stages of social interaction,” said study author Dr. Stefan Fischer, from Cambridge University’s Department of Zoology.

“Social animals need to develop social skills, which regulate social interactions, aggression and hierarchy formations within groups. Such skills are difficult and costly to develop, and only beneficial if the early social environment predicts a high number of social interactions continues to be critically important later in life,” he said.

For the study, published this week in the journal The American Naturalist, researchers used the Neolamprologus pulcher (N. Pulcher) breed of cichlid, primarily found in Lake Tanganyika — the great African freshwater lake that feeds into the Congo River.

N. Pulcher lives in family groups with up to 25 individuals, with one breeder pair and several helpers participating in territory defense and raising of offspring — known as ‘cooperative breeding’. To test for social skills, the researchers reared juvenile fish over two months with either three or nine adult group members, and observed all social behaviors at key experimental points.

These interactions included ‘lateral display’ — when one fish interrupts another by displaying their body side-on, sometimes as a mating ritual — as well as ramming, tail quivering, and ‘mouth fighting': a social display in which fish lock mouths to challenge each other over everything from food to mates.

Six month after this test phase, individual fish brains were measured to investigate the long term consequences of early group size on brain morphology, revealing differences in brain architecture.

The researchers say that one of the effects on social behavior in larger groups might be the perception of environmental risk. “In the wild, larger social groups of N. Pulcher represent a low-risk environment with enhanced juvenile survival. Being part of a larger, safer group may increase the motivation of juveniles to interact socially with siblings, enhancing the opportunities to acquire social skills,” said Fischer.

As perhaps with any social creature, Fischer points out that higher social competence and the ability to conform to social hierarchies may well stand the cichlids in good stead in later life:

“Group size for these fish stays relatively stable across the years, they have delayed dispersal. Remaining in a larger group means a better chance of survival. Fish reared in large groups showed more submissive and less aggressive behavior to big fish in the group, social behavior which greatly enhances the survival chances of smaller fish.”

Fischer added: “In highly social animals, such as cooperative breeders, almost all activities involve social interactions, where individuals need to adequately respond to social partners. In larger groups, these interactions are more common and individuals developing sophisticated social skills during childhood might highly benefit from them later in life.”

Source: University of Cambridge

Originally published here: www.sciencedaily.com/releases/2015/05/150507114048.htm

Posted May 15th, 2015.

Add a comment

Adventures in Sudan and Zambia

 

 

Lake Mweru, Zambia. Photograph by Béla Nagy.

In the June 2013 issue, Béla Nagy writes about his adventures collecting in Africa. Two of the tougher places to collect were Sudan and Zambia, and he recalls his experiences there.

By Béla Nagy

Sudan: The Only Thing You Need Is Patience

Many years ago, large parts of Africa were what people would call terra incognita, unknown land. Today, much of the land is well known, but one of the few exceptions is the relatively unexplored Nuba Mountains region of Sudan.

It is prudent to always pay attention to the counsel of those who have been in Africa, and one common piece of advice is to allow plenty of time and exercise patience. This is especially important in Sudan.

After my arrival in that country for a collecting trip in 2010, the local agency I was dealing with began the complicated administrative tasks to provide us with the necessary permits. In the end, some members of our group were denied. We had also not been granted permission to visit some areas where there was potential for Nothobranchius habitats. Therefore, we had to take a risk and visit those regions without permits. We felt very lucky because, most of the time, we were allowed to pass through the countless military checkpoints smoothly and quickly and reach our planned destinations. This may have also been due to our local driver, who prayed to the celestial beings before each control point.

Sudan is vast, and one should allow plenty of time to get from one place to another. The poor road conditions seem to conspire against you in being able to reach the destination. We headed to the breathtakingly beautiful Nuba Mountains. Sudan achieved independence only in 1956, but since then, flirtations with democracy and military coups have been regular features of the Sudanese political landscape. Color-coded markings along the roads indicate the degree of risk of land mines. Few roads traverse these mountains, and many villages are accessible only by ancient footpaths or tracks. The absence of suitable accommodation in the Nuba Mountains made our tents a worthwhile investment. Although spent cartridges and scorpions were our standard companions wherever we pitched camp, we did not feel unsafe while traveling around the country.

We collected N. virgatus and N. nubaensis at several locations. The records of the localities of Nothobranchius species in central Sudan today indicate disjunctive and sporadic distributions of the species. Most of the known locations are in the foothills of the Nuba Mountains and have, presently, no obvious links. However, the Greek historian Herodotus noted that the 100 days of annual Nile floods occurred at the time of the summer solstice when no rain fell in Egypt, and he correctly interpreted the cause as heavy precipitation in the headwaters region of the Nile during that time of year. The highly fluctuating water levels of the Nile and the earlier presence of the ancient mega-lake provided more continuous and permanent connections between the presently known populations of Nothobranchius species in that area.

At the end of the day, the trip had been safe and collecting was a success, but it was at a time just before the planned elections in the country. A few months later, a new state was born when Southern Sudan reached independence after 21 years of bloody infighting. Tens of thousands of people had fled the violence.

Even after the countries separated, the security situation remained very unstable around the new boundary between the two parts of the former Sudan. Fighting, aerial bombing, and gunfire were frequently reported from the region along the new border and from the vicinity of Kadugli. We stayed in that city overnight and collected one population of Nothobranchius just outside of the city. A considerable part of our route led us in close proximity to the new border. Hopefully, the situation will soon be stabilized and allow further field trips into the region.

Discoveries in the Footsteps of Livingstone: Zambia

Zambia is a country one dreams about when thinking of visiting Africa—mesmerizing landscapes encompassing the very best of African wilderness, an astonishing diversity of wildlife, and people with genuine friendliness and warmth. Zambia is a landlocked country at the northern edge of the region referred to as Southern Africa, at quite some distance from both the Atlantic and Pacific oceans. Most of the country is part of the high undulating plateau that forms the backbone of the African continent. Several Nothobranchius habitats are known from Zambia, among others N. symoensi, a true beauty, which we have found at five localities.

In the foyer of the British Royal Geographical Society in London are some very interesting relics that greet the visitor. In the elegantly furnished lobby is a time-worn, carefully guarded treasure—the cap worn by Dr. David Livingstone when he traveled in the heart of Africa. The cap seems to embody the courage, tenacity, and determination of the original wearer. Livingstone was the pre-eminent missionary explorer of the Victorian era who criss-crossed Africa between 1841 and 1873, including much of what is now known as Zambia.

The area around Lake Mweru, which Livingstone discovered, was one of the major objectives on our collecting trip to Zambia in 2012. The Lushiba Marsh at the northern end of the lake had not been extensively investigated and, as Nothobranchius species are known from other drainage systems in the vicinity, it seemed likely to me that we might find a Nothobranchius species inhabiting the Lushiba Marsh. The drainage system in this particular area has been isolated from that of adjacent regions for a long time, so we speculated that any Nothobranchius inhabiting the marsh might well constitute an unknown species. However, the marsh is relatively difficult to access, and that is probably the reason for the lack of extensive ichthyological surveys in the area. It took quite some time for us to reach Chienge, a village at the edge of the Lushiba Marsh, but our efforts were quickly rewarded when the first site we stopped at yielded a new species of Nothobranchius.

We spent the evening at a new guesthouse in Chienge, with splendid views of Lake Mweru. The new state of the guesthouse did not mean it was of perfect quality, and there was no running water for the ablution facilities. On the other hand, we had delicious dinner prepared from the catch of the day from the lake. This wonderful dinner was in strong contrast to the meals of the previous few days that consisted almost exclusively of fritas, a kind of local fried cake that we could usually buy on the roadside. While fritas were quite tasty, the main problem was that quite a bit of sand found its way into the ingredients, and we had to eat them carefully. The peaceful dinner was also in contrast to the night we spent at another guesthouse the previous day, where the somewhat drunken local owner wanted to force us to go with him to the local night club, which we could only avoid after a lot of negotiation.

Discovering new fish species frequently requires dedication, and there may be many difficulties that one has to overcome, but the rewards make it all worthwhile.

Posted May 14th, 2015.

Add a comment

Back to Top


Back to Top


Back to Top


Site 'Breadcrumb' Navigation:

Back to Top