THE SLOW WADDLE OF A PREGNANT DOLPHIN

We are all used to seeing acrobatic dolphins surfing and jumping effortlessly through the ocean. But until recently, we were unaware of the expectant mothers lagging behind their pod.

Dr. Shawn Noren and her team observed dolphins (located in Hawaii) for 10 days before giving birth and followed their progress for 2 years after calving. Dr. Noren observed that during their 12-month gestation period, dolphins develop a ‘bump’ akin to the ‘bumps’ seen in humans. However, for a marine mammal designed to be streamlined, the ‘bump’ could drastically affect an expectant mother’s lifestyle and lifespan!

Dr. Noren explained how the drag experienced by an expectant mother effects their speed:

“When a pregnant animal is swimming at 1.7 metres per second, it has the same drag force acting on it as a non-pregnant dolphin swimming at 3.4 metres per second.”

“So the pregnant dolphin can only go half the speed as the non-pregnant dolphin before it gets the same drag force.”

Dr. Noren also observed the arc of the tail whilst swimming reduces by 13% in a pregnant female. This is thought to be down to the location of the foetus in the abdomen creating surface tension in the mother’s skin, reducing its flexibility. 

These two factors slow pregnant females to a maximum speed of 13km/h (8mph), which is markedly slower than a non – pregnant female whom can reach speeds in excess of 22km/h (14mph). This puts them in danger of becoming ‘easy prey,’ as the top speed of their natural predators would be equal to, or higher than, the maximum speed of a pregnant dolphin.

Pregnant humans may feel ‘less streamlined’ as the weeks pass by, but at least they are not reliant on their shape to glide through the world’s oceans like these graceful mammals!

By Haley Dolton

Seahorse trade devastating wild populations

Whilst on holiday, you have probably seen shells, dried starfish and maybe, even seahorses in curio shops around the globe. These curiosities are so popular; approximately 25 million seahorses are sold per year via this trade, the pet trade and their use in traditional medicines. With little known about the actual population of seahorses, it is very difficult for conservation strategies to establish if a sustainable catch is viable in the future.

It is estimated that seahorse populations have declined between 15 – 70% in recent years because of trading and the decline of their natural habitats. Coral reefs face difficulties such as climate change, curio trade, pollution, bleaching and destructive fishing practices.  Recently the Global Coral Reef Monitoring Network have reported that globally, approximately 19% of coral reefs have already disappeared, 15% are under serious threat in the next 10 – 20 years and 20% will be lost in the next 20 – 40 years!

In addition to this, another habitat used by seahorses, seagrass meadows are also under threat from similar pressures. It has been estimated that losses of up to 90% have been seen in Chesapeake Bay (the U.S.) in the last 50 – 100 years and in just 20 years; approximately 50% of seagrass meadows have been lost in Vietnam.

Another factor contributing to seahorse declines is their biology. They reach sexual maturity late in life; consequently, they are often removed from the wild before they have time to reproduce. When they do reproduce, they have low birth rates when compared to other marine species such as fish. For example, cod can produce an estimated 200 000 eggs per spawn, whereas a seahorse will birth around 1000 young per year.

All these factors are negatively contributing to the global decline of seahorse populations. With increased awareness and education, attitudes towards seahorses are slowly changing. For example, individuals are beginning to see that seahorses are worth more alive to them because of tourism, rather than supplying them to the curio trade. This, combined with additional research into population levels, will hopefully see a sustainable conservation strategy put into place in the not too distant future before it is too late.

Haley Dolton

The helpful gardener: rats aid pollination and seed dispersal

Rats do not always provoke the best reaction from people, but hopefully, due to recent research, people may look upon them more favorably and get past their ‘creepy’ hairy tail and feet.

Historically, rats have been transported all around the world mainly by exploring travellers, making rats an invasive species across the majority of the globe. Some rat populations have played a major role in carrying diseases to new countries and devastating native flora and fauna species. However, new investigations into the role played by invasive rats in an ecosystem have been conducted and it turns out, they are not all that bad.

Recent declines in pollinating invertebrates such as bees, has resulted in pollination of flowering plants declining. This has a negative impact on food crops and the natural flora and fauna found in the wild. Insect pollination is approximately worth £141 billion per year, making a resolution to this problem not only ecologically important, but also financially beneficial.

Fortunately, other species can pollinate flowers such as bats, birds, mammals and reptiles. Dr. David Wilcove and his team have found the invasive rat (Rattus rattus) in New Zealand acting as a pollinator on the main Island. Unfortunately, this may only be because they have preyed upon the majority of endemic pollinators.

Although this research is somewhat of a double – edged sword, it was unexpected to find rats acting as pollinator for native plant species which may otherwise have suffered a major population deficit. Dr. Wilcove has suggested the rats make a successful substitute for pollinators in this instance because the plants studied do not rely on a specialist to pollinate them.

In another study, Dr. Pierre-Michel Forget and his team have discovered for the first time that the species, Kivu giant pouched rat (Cricetomys kivuensis) is helping flora seed dispersal in Africa.

Rodents in temperate climates are well known to disperse seeds far from a parent tree. For example, we have all seen a squirrel hiding their nuts for winter! Conversely, it was long thought that rodents living in tropical conditions in Africa only stored seeds deep in burrows, leaving no chance for them to germinate.

However, Dr. Forget established the Kivu giant pouched rat also scatter-hoarded large seeds, leaving any forgotten hidden seeds the chance to germinate. This not only benefits the ecosystem as whole, but also the rat directly as food will continue to be provided from new plants in years to come.

These two studies highlight the importance invasive species may be playing in certain ecosystems, which is vital to consider in future pest control schemes.

A CROAK FROM BEYOND THE GRAVE

Preserved specimens at museums always draw a crowd due to the extraordinary rarity to see whole animals preserved in liquid. Not only are they are crowd pleasers; they allow museums to catalog species we know exist on this planet.  An exciting new discovery by graduate student Tina Cheng and her team will put museum specimens to another great use.

The main focus of this study was the fungus Batrachochytrium dendrobatidis (Bd) and it’s spread across Mexico and Central America. Bd causes chytridiomycosis, a disease that is currently devastating amphibian populations with approximately 40% of total species affected by it. The disease changes both morphology and behavior and eventually leads to death.

Museum specimens are normally preserved in formaldehyde, which interacts with proteins found in DNA. This allows the fixation of body tissues to occur. Ms. Cheng and her team were able to use old specimens from the Museum of Vertebrate Zoology in Berkeley, Calif, to establish where and when the deadly fungus Bd first appeared.

Swabs were taken from frog and salamander specimens (collected in the 1960s) that inhabited the mountains of southern Mexico, western Guatemala and the cloud forests of Monteverde, Costa Rica. Interestingly, the swabs showed the presence of Bd corresponding with the earliest reports of Bd related deaths of amphibians in the wild.

Ms. Cheng and her team were effectively able to take a ‘freeze frame’ of time to show the spread if the disease. It appears Bd spread in a southerly direction across Central America in the 1970s – 1980s.

Using museum specimens in molecular research is a massive step forward in research science, as it was previously believed formaldehyde would denature the proteins needed for testing in DNA. Encouragingly, this study shows tiny stretches of DNA can survive the preserving process, leaving the opportunity for additional research to be conducted using museum specimens. As scientists are currently in the process of establishing how Bd spreads, how to stop it and how to treat infected individuals, this new research method could not have come at a more important time.

THE NOT SO GLAMOROUS WORLD OF EXOTIC PETS

The ownership of exotic pets has been brought to the forefront of people’s minds recently with instances of ownership being reported in the media. Having pets such as lions, tigers and chimpanzees, is not only harmful to the animals but also to the owners. Inappropriate, emotional bonds are formed between humans and domesticated ‘wild’ animals that will never lose their natural instincts.

One notable occurrence has been that of the Vietnamese vet Terry Thompson, who released 56 of his exotic animals into Ohio farmland and took his own life after doing so. The menagerie of animals included: 18 rare Bengal tigers, wolves, bears and monkeys, which had to be shot before they came into contact with the general public. The whole incident is speculated to have occurred due to financial difficulties of keeping so many exotic pets.

Louis Theroux has also just released a new documentary about the ownership of exotic pets in order to gain an insight as to why people believe they should own such powerful and dangerous animals. The programme was filmed once again, in Ohio where the number of exotic pets is high as the state laws are relaxed in relation to the worlds view on owning exotic pets. The limited control of exotic animal ownership is not without consequences, as 75 people have been killed and over 1500 injured by their pets.

Both these news stories highlight how dangerous these animals can be, but why do people continue to buy them? It may be that the dangerous animals are used as power symbols to enhance their owners status, for profit by selling body parts, or because cubs and primates have the cute factor when young. But when these cute animals grow up, they often outgrow their enclosure, become expensive to keep and aggressive as they reach sexual maturity. It is for these negative reasons that out of control pets are given away to establishments such as those featured in Louis Theroux’s documentary. This gives a justifiable reason for keeping them open, in addition to using them as gene pool in the future.

However, despite their proposed usefulness in the future, can conservation organisations really rely on these establishments to make sure the gene pool of endangered species are not compromised by inbreeding when it is normally controlled by an overseeing body? With approximately 5000 Bengal tigers (5% in recognised zoos) kept in captivity in 2004 in the USA alone and only 3200 Bengal tigers in the wild, this is an increasingly important question to consider.

Keeping exotic animals is not a practice everybody agrees with and less than 24 hours after the massacre in Ohio was reported to the general public, approximately 28 000 people signed a petition to ban the sale and ownership of wild animals. There needs to be a shakeup in terms of the laws surrounding owning a dangerous animal as a pet. It should not, in today’s society, be acceptable to be able to buy unchecked numbers of tiger cubs in car parks for $200/cub as reports suggest. Nor is it acceptable for the owner to put themselves in constant risk of being attacked and killed by a loved pet.

If laws surrounding wild animal ownership are stringently controlled in countries which currently permit it, they could provide an invaluable service to conservation in the future. This is because the release of endangered, captive bred individuals into the wild may be considered as a way to reverse depleted populations. But until it is controlled, how long before we hear of another incident similar to the one in Ohio or before an owner is killed?

KILLER WHALE CHANGES ITS COLOUR

Whilst watching Frozen Planet, has it crossed your mind why the killer whales in the Antarctic are slightly off colour? This slight yellow tinge is caused by nutrient rich diatoms and algae found in these chilly waters which attach to the mammals skin. John Durban of the NOAA has offered a new proposal as to why a certain type of killer whale will migrate thousands of miles in relation to this yellow tinge.

Since the killer whales travel at a constant speed during this migration, researchers believe that they are not traveling to find prey or to give birth. Type B killer whales (which feed mainly on seals) were tagged off the Antarctic Peninsula and it was revealed that they move towards sub – tropical waters continually. One tagged individual travelled over an incredible 5, 000 miles to Brazil, only to return just 42 days later to Antarctica! The speed and distance travelled is unprecedented in killer whales and it implies the individual departed from Brazil immediately, but why?

Killer whales return from this journey to warmer seas ‘cleaner’ than when they left. It is thought the warmer water helps killer whales to shed the algal growth and regenerate skin tissue. It is possible that the energy they would need to expend in the cold Antarctic waters can be utilised to repair any tissue damage created by diatoms or algae. Further evidence for this theory is shown by killer whales actually slowing down their speed in warmer waters. They do not travel slowly enough to indicate calving or extensive feeding, but it would give the killer whales extra time in warmer waters to shed and heal their skin.

As more research is conducted on these beautiful mammals, the more we are finding out about how clever they are. This may provide interesting comparisons when researching into the evolution of intelligence and how similar to the intellectual capability of humans they may be.