Fish ashore at coastal waters in many areas

Last week, fishermen and the community in the East coast were surprised by the influx of fish on the shore. Experts say this is due to a coastal current that resulted in the fish being washed ashore.

It was frenzy of fishing at the coastal areas in the east last week. Lots of fish had been swept ashore enabling the public to catch them by simply using a net or a piece of cloth. Many gathered to see this phenomenon and get fish for a free meal. Some of course kept their distance fearing that the aggregate of the fish could be some bad omen like the advent of another tsunami. Sardines were the most commonly found fish in addition to the skipjack tuna among the schools of fish.
Reports of fish being washed ashore had puzzled the general public even in other areas; some feared that this could be the sign of an incoming disaster. But oceanography experts say that there is nothing to worry and the sudden aggregation of fish is normal. They connected this to the changes linked with the monsoonal patterns. Oceanography expert Dr. K. Arulananthan at NARA (National Aquatic Research and Development Agency) confirmed that this was due to the changing patterns of the East Indian coastal current.

Change of temperature
Sri Lanka is now experiencing the second inter-monsoon rains. According to Dr. Arulananthan, during the south western monsoon, the East Indian coastal current flows from the Arabian Sea towards the Bay of Bengal via the southern tip of Sri Lanka. But with the north-western monsoon the direction of this East Indian coastal current reverses and this happens during the inter-monsoon season. This brings cold water from the Bay of Bengal region and the change of temperature assists in the growing of algae and planktons that leads to algae bloom. Little fish gather to feed on these microscopic plankton and even big pelagic fish that live in open seas follow the smaller ones making this present fishing frenzy in many areas, explained Dr. Arulananthan.
The sardines or keeramin and skipjack tuna are the most notable fish that had gathered in numbers during past few days. The said phenomenon is more applicable for pelagic fish, comments Dr. Arulananthan. The expert also spoke of another possibility of dead fish being washed ashore. The algae also perform photosynthesis which consumes the oxygen in the water. In the waters where algae bloom, the fish find a lack of oxygen, and many die. Some of the dead fish get washed ashore while others sink deep down to the bottom of the sea. The decaying fish at the bottom deplete the oxygen in that region which affects the fish that dwell in the bottom, like eel or ray fish.
This year, Sri Lanka experienced a delayed south west monsoon and perhaps these climatic changes aggravated the oceanic current to make it more observant. However, Dr. Arulananthan calls it a normal phenomenon adding that one need not worry, unduly. But the climate change may bring more abnormal changes of weather patterns that lead to phenomena’s like this in the future, experts fear.
Many feared that this could be a bad omen as they recalled that just before the 2004 tsunami, loads of fish were seen in a similar manner. Dr. Arulananthan reminded that the tsunami occurred in December and this phenomenon of the changing of the East Indian coastal current was in October. He also said the underwater earthquakes might make the lives of fish dwelling in the deep sea to migrate to other regions via oceanic currents. However, the fish caught during last few days are not abnormal species but ones that are commonly found in our oceans.
However, it is interesting to know that the changes of climatic patterns affect animal behaviour as ZooLander reported recently about a dragonfly migration that follows Inter Tropical Convergence Zone which fell during the same time period across Sri Lanka.

Climate change shrinks fish size, says new study
A new scientific study shows that climate change will shrink the size of fish by 14-24%. This too links to the level of oxygen in the water where scientists say the increase of temperature will reduce the oxygen in the water. Researchers from the University of British Columbia have studied change of body size of some 600 species based on models between 2001 and 2050.
Although data projects relatively small changes in temperature at the sea-bed, the resulting impact on fish body size are “unexpectedly large,” BBC has reported. When compared with actual observations of sizes of the fish, models generated on future sizes of fish seem to underestimate what’s actually happening in the seas. The researchers looked at two case studies involving the North Atlantic cod and haddock. They found that the recorded data on these fish showed greater decrease in body size than what the models had predicted. Other scientists stated the impact could be widely felt.
A warmer and less-oxygenated ocean, as predicted under climate change, would make it more difficult for bigger fish to get enough oxygen, which means they will stop growing sooner, the research report states.
The fish stocks around the world are already being depleted due to overfishing.
Climate change due to global warming will also make the ocean acidification that impacts on the fish and this study will be another blow.
According to experts, the ocean acidification is a phenomenon that is triggered by the increase of carbon dioxide in the atmosphere. When the Co2 mixes with sea water, the oceans get more acidic. This impacts the many delicate species and ecosystems as corals on the first wave of attack and then will impact the other fish species too, experts point out.
Other species like the mollusks that have shells that are built by calcium carbonate too could be in danger as another report suggests. Calcium carbonate dissolves in acids and when the sea water gets more acidic, their shells will thin exposing them to predators and other hostile elements.
Researchers point out that the worst impact could be observed in the tropical regions; so countries like Sri Lanka will badly affected. Scientists argue that failure to control greenhouse gas emissions will have a greater impact on marine ecosystems than previously thought, the BBC reported.

How Global Warming affects Biodiversity of oceans

   The ocean has absorbed 80 per cent of the heat added to the Earth’s system by climate change.

    Warmer waters cause coral bleaching, which in turn negatively impacts the entire coral ecosystem.

    Many species will be forced to migrate so they can maintain the temperature conditions they need for feeding and reproduction.

   Alteration to water temperature can directly impact development, age of sexual maturity, timing of spawning, growth, and survival of most fish.

    Decreased upwelling due to warmer waters means that fewer important nutrients from lower in the water column will make it to the surface of the water. Many important marine ecosystems almost completely depend on nutrients from such upwelling areas – for example, marine habitats around the Galapagos Islands and along the US coast of California.  

  Acidification directly harms the many ocean plants and animals that build shells of calcium carbonate – including many tropical reef-building corals, coldwater corals, mollusks and other scallops, crustaceans such as lobsters and crabs, and some microscopic plankton that make up the foundation of the food web throughout most of the ocean.

    Many of those same shell-forming organisms provide critical habitat and food sources for other organisms.

How it impacts human welfare:
As in all instances, people are directly linked to life around them. People and many industries around the world rely on the ocean for food and other natural resources. For instance, upwelling areas provide some of the richest fishing grounds in the world. Likewise, coral reefs provide habitat for fish and other protein food sources for people, as well as important tourism economies in many areas. As warming ocean waters impact life within the ocean, humans and industries dependent on them are likewise impacted.

Source: www.conservation.org

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Komodo Dragons, Mongolian Horses and River Hippo arrive

Welcome to the Dehiwala Zoo

Last week the zoo was busy getting ready to welcome three new pairs of animals. They arrived last Thursday and were put in their ready-made enclosures so that visitors would be able to see them. Together with River Rhinos and Mongolian Wild Horses there was a pair of Komodo Dragons – first time residents at the
Dehiwala Zoo.

It was night when the special cargo plane C-130 Hercules belonging to the Sri Lanka Air Force landed safely at Katunayake last Thursday. The plane came from the Czech Republic. The plane had on board six, huge boxes with ‘live’ cargo. These craters had a pair of Komodo Dragons, a pair of Przewalski’s Wild Horses and River Hippopotamus.
The animals came directly from the Prague Zoo of the Czech Republic. The animals would have been tired after the journey as well as going through jet lag as they had to travel over 20 hours, barring two stopovers en route. A veterinary surgeon and some caretakers from the Prague Zoo accompanied the animals on their journey to Sri Lanka.
Once the documentation was completed at the airport, the animals were transferred to the Dehiwala Zoo, accompanied by staff of the zoo. It was reported that the animals were transported to the Dehiwala Zoo with the driver taking much care during the journey to ensure that the already tired animals will have a trouble free journey to Dehiwala. 
At the zoo, another group of workers and animal caretakers were anxiously waiting to welcome the newcomers. Their enclosures had been cleaned and prepared to receive the animals as they start their new life at the Dehiwala Zoo. A group of Young Zoologists’ Association (YZA) members too had been supportive once the animals arrived at the zoo. On arrival, the animals were found to be examining their new enclosures – similar to newcomers in a home.

Komodo Dragons
It is the first time in the history of the Dehiwala Zoo that it has welcomed Komodo dragons. Komodo dragons are found in Indonesia’s Komodo Island and some other nearby areas, hence its common English name. Dragons are gigantic and in legends, breathe fire, but these Komodos are like the over-sized local kabarayas or water monitors. But they have a voracious appetite – they eat much more than our kabaraya and sometimes lay in ambush to hunt. It is said the buffalo or deer would be the preferred diet of a grown Komodo dragon but they even eat carrions if opportunity strikes for an easy meal.
The Komodo dragon is special as it is the largest lizard that lives on earth. The yellow colour of the Komodo’s long, forked tongue reminds people of mythical dragons that spit fire according to legend. The tongue is special for them as it is used to taste the air to pick up the smell of the prey. It is recorded that they can pick up smell over a mile; so when there is a victim, the Komodo’s in the vicinity gather to feed on the carcass.
An adult dragon will hide along a trail and wait for an unsuspecting creature to walk by. Using its long claws and short, sharp teeth, the dragon will attack. If the prey manages to get away, the dragon will simply follow at a leisurely pace as a dragon’s bite contains deadly bacteria that will eventually kill its intended meal. The Komodo dragon is known to have 50 different types of toxic bacteria in their saliva that thrive on traces of flesh, causing bite-wounds to become quickly infected. Recent research however indicates that the real reason for such a high success rate in poisoning the prey could be due to the fact that the Komodo dragon may have a venom gland in its mouth.
In Komodo Islands, their habitats are been destroyed and they are pushed closer to human settlements. There are records the Komodo dragons have attacked humans as well. Even in captivity, they can be dangerous and there are records of attempted escapes. So in the Dehiwala Zoo, the Komodo dragon has an enclosure which is reinforced to the ground as well. Komodos are burrowing animals, so there would be a chance that they keep digging a tunnel under the enclosure so as to slip out.
To prevent this, a metal mesh has been fixed on the ground with sand placed on top of it. But it is better to keep your distance when you visit the zoo to have a closer encounter with these animals.
Class       : Reptilia
Order       : Squamata
Suborder  : Lacertilia
Family       : Varanidae
Genus       : Varanus
Species       :
Varanus komodoensis
IUCN threatened
category : Vulnerable

River Hippos

The Dehiwala Zoo has many Pigmy hippos that are smaller in size, but the River hippopotamus – a very larger cousin of the pigmy, died few years back. The female died attempting to give birth and the male died some time later. The hippo’s enclosure is near the new elephant arena that is being built in a corner of the zoo. Nile hippopotamuses grow up to 15 feet long. Males are heavier than females, weighing up to 8,000 pounds. Nile hippos stand at four and a half to five and a half feet tall.

Class    : Mammalia
Order    : Artiodactyla
Family    : Hippopotamidae
Genus    : Hippopotamus
Species    : Hippopotamus amphibious
IUCN threatened category : Vulnerable

Przewalski’s Horse

Mongolian Wild Horse or Przewalski’s horse is special for any zoo as they are saved by the conservation efforts that zoos take. They had gone ‘extinct in the wild’ in the 1960s and only the horses in the zoos remained. The Zoological Gardens had conducted a special programme to breed these horses. After the captive population grew, the Wild Horses were reintroduced back into the wild. Now they have made a comeback and jumped two steps to the positive side of IUCN Red List category to end up in the “Endangered” level.

Order          : Perissodactyla
Family             : Equidae
Genus          : Equus
Species          : Equus ferus
Subspecies : Equus ferus przewalskii
IUCN threatened category : Endangered

Jumbo Shipment

The military plane from Sri Lanka didn’t go to Czech Republic ‘empty-handed’ either. The plane carried a pair of elephants to the Prague Zoo. They were Janitha (8 years) and Amara (7 years) – male and female elephants from the Pinnawala Elephant Orphanage. It was a promise made by the Sri Lanka government to donate elephants to the Prague Zoo to support their Asian Elephant Breeding programme. This is therefore different from a normal animal exchange programme, commented the director of the Prague Zoo in reply to a query by a local newspaper in the Czech Republic. The elephants however had to travel nearly 30 hours with three transits to reach Prague, said officers of the zoo. The military plane has been prepared for this long flight, and it was a good experience for all those who were involved in the exercise of transporting the animals on the plane. 

Published in LakbimaNews on 21.10.2012 http://www.lakbimanews.lk/index.php?option=com_content&view=article&id=7282:welcome-to-the-dehiwala-zoo&catid=41:mag&Itemid=12http://www.lakbimanews.lk/index.php?option=com_content&view=article&id=7282:welcome-to-the-dehiwala-zoo&catid=41:mag&Itemid=12

Could there be a Dragonfly migration across Sri Lanka?

Citizen’s support is sought to make observations...

Last year, around this time a large cloud of Dragonflies was observed along the west coast near Colombo which could be part of an amazing Dragonfly migration. With the rains, could Dragonflies too appear as a wave this year?

his wave of Dragonflies was first reported moving toward the South in large numbers on October 20 (morning) last year. Nashath Haffi of the Field Ornithology Group of Sri Lanka (FOGSL) who had witnessed the flight said that he had observed this wave around 7.00 in the morning along the coast, continuously from Moratuwa to Kollupitiya while he was travelling on the train. Susequent investigations confirmed this phenomenon as the beach community in Dehiwala and the west coast also confirmed seeing the large number of Dragonflies.
Some of the residents living near the beach said this swarm of Dragonflies appears with the change of wind or goda sulan most of the years. Further investigations also revealed that a Dragonfly Migration from the Maldives to Africa was reported by a well known naturalist, Dr. Charles Anderson. Dragonfly larvae can survive only in freshwater pools, but there are no freshwater pools in the Maldive islands. So the dragonflies that are present in the Maldives have to migrate.
Dr. Anderson had noted the dates when the dragonflies were seen the first time in the Maldives, and then compared the data with the appearance of Dragonflies in South India. He found a clear sequence of dates of arrival from the north to the south. According to these data, dragonflies first arrived in Southern India and then in the Maldives. According to his research, each year, dragonflies first appear in Maldive's capital, Male, between October 4-23, with a mean arrival date of October 21. Quite interestingly, the sighting of the dragonfly wave in the west coast of Sri Lanka was reported on October 20, which is quite close to the dates they had arrived in the Maldives. Therefore one can speculate that the dragonflies seen in Sri Lanka must also be those that were involved in this migration.
Dr. Anderson also attributes the wind pattern that helps them in this journey. In October, and continuing into November and December, a weather system called the Inter-tropical Convergence Zone moves southwards over the Maldives. Dr. Anderson suggests these dragonflies must be flying on these winds at an altitude above 1000m. “Ahead of the ITCZ the winds blow towards India, but above and behind it, the winds blow from India. So it seems that the dragonflies are able to reach the Maldives by flying on these winds at altitudes above 1000m,” he stated. This would probably assist them to visit Sri Lanka too.
In the past week there was rain in many parts of Sri Lanka. So perhaps the time is right for this interesting phenomenon, and the dragonfly swarm could be seen any time these days.
The Field Ornithology Group of Sri Lanka that first studied this phenomenon is now looking for more data of the presence of Dragonflies to solve this mystery. The society seeks the support of the general public to collect data on the sighting of large movements of dragonflies.

Migrant Birds too are here now…
Among the many types of birds that migrate are some of the common species such as the Blue-tailed Bee-eaters that can be commonly seen even in Colombo. It is also a fun exercise to note down the days these migrants first appear and the days they disappear at the end of the migration season. FOGSL that is based in the University of Colombo asks the general public to keep a log on the common migrants that can be seen and share the information with everyone at the end of migration season. Some of these migrant birds find their journey across hundreds of miles, exhaustive. Last year, as per the announcements through MigrantWATCH, the lives of some of the troubled migrants were saved. FOGSL invites the public to be vigilant this year too.

MIGRANT WATCH – You too can support science

Much research is needed to solve the mysteries of migration. The first step would be to monitor where the dragonflies have been seen in large numbers, which will give the coordination of a possible map. FOGSL that initiated a programme called MIGRANT WATCH also invites the general public to send information on the movements of dragonflies.
The Migrant Watch mainly aims at observing migrant birds and dragonflies as a Citizen Science project. The power of observation, even by non-experts, can contribute towards collecting information in this regard. FOGSL invites all to participate in MIGRANT WATCH. The data can be emailed to fogsl@slt.lk This e-mail address is being protected from spambots. You need JavaScript enabled to view it or by post to: FOGSL, Dept. of Zoology, University of Colombo, Colombo 3. Further details can be obtained by calling 2501332 or 0712543634.

Published on LakbimaNews on 14.10.2012 http://www.lakbimanews.lk/index.php?option=com_content&view=article&id=7203:could-there-be-a-dragonfly-migration-across-sri-lanka&catid=41:mag&Itemid=12

Alligator Gar: The Gator Fish

It swims like a fish but has elongated jaws with sharp teeth that are visible when it opens its mouth, similar to an alligator or a crocodile. So is it a fish? Or is it an alligator? I am not sure who had named this fish which has been scientifically described in 1803, but it has been given a common English name to match its characteristics. The fish is named Alligator Gar.
The fish is generally olive green or yellow and has a heavily scaled body. A tooth-filled mouth and wide, alligator-like snout give the species its name. With a prehistoric look, the Alligator Gar is one of the largest freshwater fish. Its name is derived from the alligator-like appearance of these teeth along with its elongated snout, and is indeed the largest freshwater fish in North America. A mature Alligator Gar fish can grow up to 10 feet and can weigh over 90 kilograms. It has been one of the largest and toughest fish, and the alligator gar is a favourite target of anglers who love this particular sport of fishing.
The alligator gar has a streamlined body to facilitate swimming and its dorsal and anal fins are located very far back on the body. Gars’ bodies are covered by ganoid scales, which are thick overlapping scales that create a protective covering similar to medieval chainmail – like those worn by heroes of favourite movies such as Robin Hood or Gladiators.

The river giant
These menacing-looking fish are indeed prehistoric. Scientists track the gar’s tenure on earth back to 150 million years to about the time birds began to fly. Although fossils of gars have been found in North America, Central America, Europe and Asia, the living members of the family are restricted to seven species living in North and Central America.
The Mississippi River in North America is recorded to be the alligator gar’s main hideout. They can live in fresh and brackish water bodies. The fish, despite its giant size, is relatively passive and prefers to live a solitary life. Alligator gar can also breathe air directly which allows them to survive even in murky waters. According to some literature, there are records of alligator gar having lived on land, and that is something people find surprising. They have been known to survive on land for a period of up to two hours. They may be on land to look for food or to escape from predators.

Predatory fish
Alligator gar is a carnivore fish as anybody can guess by seeing their sharp teeth. Alligator gars have two rows of teeth. The inner row of teeth is palatine and is longer than the outer row of teeth which gives them a good bite of their prey. The teeth of the alligator gar are long, slender, and fang like, giving them a good bite of their prey. They have ambush techniques in hunting prey, feeding by lurking amongst reeds and other vegetation. They like staying hidden and launch their attack on the unwary prey, and generally the prey doesn’t even know the gar is present until it is too late. They lie still in the water until an unsuspecting fish swims by, and then lunge forward and lash the head from side to side in order to capture the prey. Many times gars will lie still at the top of the water for long periods of time, appearing like a log.
Alligator gars prey on fish but they are opportunistic and have been known to feed on everything from waterfowl and small turtles to carrion. Alligator gars have been reported to attack duck decoys and eat injured waterfowl shot by hunters.
There are also speculations that larger alligator gar attack humans. But there has been no confirmation of such attacks. Though they wouldn’t attack human, their eggs, if ingested, are poisonous to humans.

Popular aquarium fish
All the Gar species are popular aquarium fish and quite interestingly the alligator gar is one of the most popular. But they are quite demanding, needing clean water as well as lots of space as they grow. In the Dehiwala Zoo the alligator gar has a moderately spacious tank. The tank has been enriched with suitable habitat to the alligator gars with some decayed logs and large stones placed within. Alligator gar like such hiding places.
Records show that there are seven gar species in the world. The alligator gar is the largest. Of the seven known gar species, the alligator is the largest and the heaviest. They weigh around 300 pounds (140 kilograms) according to records.
The breeding habits of alligator gar still remain largely unknown, but it is believed that they spawn on flood plains that expand towards the river ecosystems. Alligator gars are thought to spawn in the spring by congregating in large numbers with a female and one or more males on either side to fertilize the eggs. Web resources indicate that females generally carry an average of 138,000 eggs. The eggs are released and fertilized by the male outside of the body. They sink to the bottom after being released and stick to the substrate due to an adhesive outer covering. The eggs are bright red and poisonous if eaten. Alligator gars are thought to spawn in the floodplain of these large rivers mainly to give their young protection from predators.
They grow slowly and take a long time to mature. Females mature at 11 years and live up to 50 years. Males mature at six years and live to at least 26 years.

Conservation
The alligator gar is disappearing from many parts of the range, and declining in population everywhere due to over-fishing and the construction of dikes, dams, and other flood control mechanisms resulting in loss of key breeding habitats. The alligator gar was once reported as common and even numerous in much of its northern range. Now it is rare in the northern parts of its range with reports of valid sightings coming in once every few years.

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