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 Post subject: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 11:53 am 
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Objective : to inform other interested forumites about the interesting, often not much known about inhabitants of the KRUGER NATIONAL PARK.

Source :

The Freshwater Fishes of the Kruger National Park - Dr. U de V Pienaar.

Fauna and Flora - Publications by the Transvaal Department of Nature Conservation

A Complete Guide to the Freshwater Fishes of Southern Africa - P. Skelton.

and own notes taken at numerous taken from numerous wildlife seminars.

Dr. Rocco. Knobel - Chief Director of the then NATIONAL PARKS BOARD wrote :

These graceful and fascinating creatures inhabit the sparkling waters of all our rivers and and streams and the placid depths of our dams, pools and veld pans. They are seldom seen by visitors, except during the annual migrations, when they attempt to negotiate obstacles impeding their progress and jump to prodigious heights or wriggle laboriously up almost perpendicular surfaces such as dam walls or weirs. Other less fortunate individuals, may also be seen struggling for survival in the choking mud or dessicating pans or pools.

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I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


Last edited by gmlsmit on Tue Apr 28, 2009 1:41 pm, edited 1 time in total.

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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 12:41 pm 
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The Freshwater Fishes of the Kruger National Park - Dr. U de V Pienaar.

This book is hard to get, but I see that I can buy it in Belgium, secondhand of course. It seems to be in good condition, and costs 6 euro, or in other words something like R75. PM me if you want it...
Edit: It's sold already, as was Die paddas van die Nasionale Krugerwildtuin and The reptile fauna of the Kruger National Park.
My copy was 15 euro, and at the time I bought it another copy was for sale. I sort of declined that, 450 euro for a little book is slightly too much I think! ;)

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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 1:03 pm 
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Location: Sydney and southern Africa
Spent an engrossing half hour on the bridge near Lower Sabie once watching some very big tiger fish cruising about.

Also, Mrs P and I had lots of fun wastching fish (I have no idea) swimming upstream, leaping over the weir at the river crossing near Phabeni Gate on the last trip, after the rains had come.

I guess if you've done mamals, insects, reptiles, birds and trees you've got to get into the fish. Would love to learn more.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 1:30 pm 
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gmlsmit! :D
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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 1:31 pm 
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The KRUGER NATIONAL PARK is drained by mainly east flowing systems.

There are two main drainage systems : the LIMPOPO system and the INCOMATI system.

The perenial rivers being the Levuvhu, Mutale, Groot Letaba, Olifants, Sabie and the Crocodile Rivers, normally placid flowing streams during the dry season, the water normally relatively clear. During the rainy season the rivers are in full spate, often muddy and turbulent.

Seasonal rivers, those that only flow for a short while during the rainy season, normally incorporate a series of permanent and semi permanent pools along their length.

The differenent systems are made up as follows :

Limpopo System

Levuvhu River - the perennial river with seasonal rivers being : Matukwane, Madziringwe, Mashikiri and Mutale.

Shingwedzi River - the perennial river with seasonal rivers being: Dzombo, Shisha, Bubube, Phugwaqne and Mphongolo.

Groot Letaba River - the perennial river, with seasonal rivers being Shipikane, Hlanganini, Ngwenyeni, Makhadzi, Klein Letaba, Mbyashishi and Tsende.

Olifants River- the perennial river, with seasonal rivers being Bangu, Timbavati, Shisakashangondzo, Nhlarulume, Klaserie and Tsutsi.

The Incomati System

Nwanedzi River - the perennial river, with the seasonal rivers being Sweni, Mtomene and Gudzane.

Nwaswitsontso River - the perennial river, with the seasonal rivers being : Munweni, Nkuane and Vutome.

Sabie River - the perennial river, with the seasonal rivers being : Nwathimhiri, Nwashitshaka, Mtsawu, Mnonodzi, Sand, Mutlumubi and Nwatindlophu.

Crocodile River- the perennial river, with the seasonal rivers being : Nsikazi, Mtjulu, Mlambane, Mbyamiti, Bumi and Vurhami

Water temperatures depend on the ambient temperature and the volume and flowing speed, and also often form a thermal barrier being the cut off points for different species. The faster and deeper, the water flow, the relatively lower the water temperature. Water temperaures vary between 16 C and normally 33 C in exceptionally hot days.

pH levels is normally between 7,6 and 8,3 = alkaline during extremely dry periods the pH level could increase to 8,6.

The turbidity of the water affects the depth of sunlight penetration and has a great influence on the richness or poorness of the aquatic habitat - the distribution of the freshwater fishes. Very often fish swim up the tributaries to spawn, or to escape the muddy flood waters.

The heavily silt laden Levuvhu River is the legacy of erosion caused by poor farming practises upstream, support very fish fauna while the clearer pools in the seasonal tributaries again harbour a very rich and diverse aquatic fauna. The muddy waters of the Levuvhu offers ideal cover for the Crocodiles which contributes signifcantly to the depletion of the fish life.

The fishes of the KRUGER NATIONAL PARK feed the mentioned Crocodiles as well as the Fish Eagles, Kingfishers, Ospreys, Fishing Owls, Herons, Storks, Hamerkops, Darters and Cormorants as well as Otters, Monitors, Terrapins and Water Mongoose. These predators together with the periodic flooding and drying of the systems keep the fish fauna population in balance.

Habitat selection is also crucial to the survival of the species, some prefer rocky areas, others, sandy,others muddy, others clear, others coloured, others fast flowing, others, placid flowing, others pools - shallow or deep, or a combination of some of the above, or some just the vleis, flood plains and pans, to ensure survival and good health.

Many fish live for many years, often reaching maturity at the agre of eight to ten years, others are seasonal- the complete their lifecycle within one season.

The main threat to the survival of the Fishes of all the World, is pollution, caused by overpopulation and greed. Human and Industrial effluent is disposed of in the waters of our Rivers, introducing foreign conditions being acids, salts, enrichment. Catchment dams and weirs without fish ladders, disturb the migration of species, upsetting their breeding patterns and cycles.

I have spent much time parked on the Lower Sabie bridge watching the resident Mud Fish going about their day's business. Much time has also been spent by me and my wife at Nkuhlu watching the small shoals of Tilapia enjoying there freedom, and at Skukuza watching the fish lazily sunning themselves on a winters morning and at the bricge crossing the Shongololo watching the Barbel feeding on whatever being available, once we were fortunate enough to watch some small silvery, and blue tinged Tiger Fish with their red edged fins, hunting in the clear waters of the Crocodile River.

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No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 1:39 pm 
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I am not advertising but should anyone have the need to learn more, get the book mentioned by DuQues, it is a hive of information. Mine is a first edition and well worn and to me very precious.

ISBN 0 86953 025 9 soft cover
and
ISBN 0 86953 026 7 hard cover

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I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Tue Apr 28, 2009 2:41 pm 
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One of the rarer seen fishes in Kryger is the Spotted Killifish.
These fish are annual, which means that the live for less than a calenderyear. The waters they live in are mostly temporary, and dry up completely during the dry season. The eggs survive this in the surface layer of mud until the rains allow them to hatch. The young grow very rapidly and are sexually mature and spawning at the age of 6~10 weeks.

(Read more about it.)

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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Wed Apr 29, 2009 10:23 am 
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Tigerfish
Tiervis
Hydrocynus vittatus


Hydrocynus = Striped Water dog.

Family : Characidae

The top predator of the South African Freshwater Fish and one of the most beautiful.

Description :

Silver streamlined body with normally about eight horizontal blue to black stripes and a bluish sheen on the back. Large bony head, each jaw equipped with eight sharp protruding teeth. The eyes are prominent and well developed. The fins are pointed and coloured yellow to blood red with often a black tinge - more prominent in the deeply forked tail. It has a pominent dorsal fin with a black adipose fin towards the rear. A pair of chest fins and a dorsal and anal fin finish of the appearance of this beautiful fish. Male and female Tigerfish are similiarly built and coloured, the females of the species grow into the larger sizes - exceeding 70 cm in length.

Biology and Ecology

Tigerfish are inhabitants of open well oxygenated warm waters such as found in the larger rivers and lakes. Clear waters are their preferred hunting area as they hunt mainly on sight. Younger fish hunt in moving schools, only the larger fully grown ones hunt on their own. Tigerfish normally swim close to the water surface where they often become of an African Fish Eagle always on the lookout for a meal.

Males reach puberty at the age of 3 to 4 years ( length 30 to 40 cm), breeding females normally exceed 40 cm and are older than the males. Breeding takes place in summer when the adults migrate to suitable spawning areas. A large female Tigerfish can bear up to 780 000 eggs. Tigerfish do not normally breed in the Kruger Park, they migrate to Mozambique where they spawn and the fry hatch, small hatchlings are often seen in the rivers of Kruger, they already have completed a long trek their new temporary home.

Tigerfish have not yet been bred sucessfully in captivity.

The tooth structure changes from cone shaped at the fish length of 10 to 25 mm to the razor sharp ones when fully grown. Worn teeth are replaced by a new set, grown in a groove just underneath the functional teeth.

Newly hatched fry feed on invertebrates and and sooplankton, and soon change their feeding habits to a fish diet normally at the length of 75 - 100 mm. They may supplement their diet with aquatic insects.

Tigerfish hunt on sight and will take any prey up to 40% of it's own length. It will grab the prey from the side and swallow it whole, head first. Common prey species are from the Tilapia, Barbus, Labeo species as well as Gobies.

Adult Tigerfish caught in the Park average 1,5 to 2,5 kg in mass, however larger specimens of up to 6.0 kg have been taken inthe Sabie, Komati, and Letaba Rivers. The Tigers in the lakes and rivers further north grow much larger, specimens up to 15.5 kg have been caught.

Distribution

Except for the Kunene and Kafue Rivers and the upper reaches of the Save-Runde Rivers and thge Lake Malawi they frequent most of the Lakes and Rivers of Africa with warm and well oxygenated water.

In the Kruger Park they are found in the perrenial rivers below 300 m from the Crocodile up to the Limpopo Rivers.

Threats

Pollution, leading to increased acidity, oxygen deficient, stagnant water will lead to decreased Tigerfish populations as well as dam walls and weirs without fish ladders, restrict their movement and intefere with their breeding habits. Exceptional cold spells will also lead to their decline as they are very thermal sensitive.

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I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


Last edited by gmlsmit on Wed Apr 29, 2009 5:52 pm, edited 1 time in total.

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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Wed Apr 29, 2009 5:50 pm 
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Largescaled-Yellowfish
Grootskub-Geelvis
Barbus marequensis


Family : CYPRINIDAE

Description

Depending on the turbidity of the water in which they live these beautiful creatures' colour varies between silvery to golden to olive, the clearer the water the more pronounced the golden, with a white undeside. The variable in size, dorsal fin positioned slightly in front but still above the pelvic fin. It has a pair of pectoral fins as well as an anal fin and a forked tail.

Both male and females grow two pairs of barbels. The eyes are positioned in the upper part of the bony head. The mouths with no teeth, of all Large Scaled Yellowfish are chisel shaped with a cutting lower jaw. The lips are placed below the snout. Depending on their surroundings they may grow "rubber lips " in the more rocky waters, and revert to normal lips in less rocky ( softer ) surroundings. The size of the lips are therefore of no diagnostic value.

Biology and Ecology

These fish have the habit of moving upstream during spring and early summer, normally after the first good rains, in order to find suitable spawning conditions.

The diet consists of aquatic insects, molluscs, snails, crabs and small fish as well as plant detritus, midge larvae and mayflies.

Males reach puberty on reaching the length of 70 mm and females at the length of 280 mm.

They prefer the Lowveld area, below 600 m where they grow to a length of 480 mm, reaching a mass of 6.0 kg.

Distribution

In all the Kruger Park's perennial rivers and their tributaries, preferring deep rocky pools below the rapids where the lie in ambush for their prey.

Threats

Water polution caused by domestic, agricultural, industrial and mining waste deposited into the feeder systems, changing the water to a low pH (acidic ).

_________________
I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


Last edited by gmlsmit on Thu Apr 30, 2009 8:48 am, edited 1 time in total.

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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Wed Apr 29, 2009 6:32 pm 
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In Desember we drove over a water way on the S65.The river dropped off at the 1 side (bout 1m drop).There were fish jumping up the little drop to swim upstream.I know this behavior isn't uncommon!Does anyone have an idea which type of fish this might have been?


June 19-20 Pkop
June 21-24 Croc B

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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Thu Apr 30, 2009 10:17 am 
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Guide to the Fish Families

In the absence of pictures I will try and give a rough guide to the Freshwater Fish families.

A few terminology explanations :

Caudal fin = tail fin either forked, rounded, truncate, pointed or emarginate.

Confluent fins = fins meeting at rear end replacing tail.

Scales: cycloid = smooth free edged, ctenoid = rough edged.

Fins :
Dorsal = on top of back
Pelvic = on the bottom normally under belly.
Pectoral = on chest close to gills.
Anal = on bottom, near anus.
Adipose = fatty on top close to tail

Barbels : slender tapered and sometimes branched appendages around the mouth or nostrils.

LEPIDOSIRENIDAE
Lungfish: body elongated; scales small;dorsal and anal fins confluent; pectoral and pelvic fins filamentous.

ANGUILLIDAE

Eels: body elongated,; scales minute, embedded; dorsal and anal fins confluent, without spines; pectoral fin, small and fan like; no pelvic fin.

CLUPEIDAE

Sardines: scales fine, easily shed, on body only; ventral scales may form keeled scutes; fins without spines.

MORMYRIDAE

Elephantsnouts: mucous skin or envelope over head and or body;dorsal and / or anal fin long based and far back, caudal fin scaled forming two lobes; gill openings small; mouth small and destinctive, usually on a fleshy snout.

SALMONIDAE

Trouts : scales small, on body only; small lobe like adipose fin present; mouth large with canine teeth.

GALAXIIDAE

Galaxias : no scales; dorsal fin far back and over anal fin; pectoral fin large and fan like.

KNERIIDAE

Knerias : wide straight ventral mouth; small scales on body only; gill openings small; males often have shell-shaped disc over gill cover and behind gill opening.

CHARACIDAE

Tigerfish, Robbers : adipose fin present, mouth large with sharp canine or multicuspid teeth; cheeks with bony plates.

HEPSETIDAE

Pike : adipose fin present; dorsal and anal fins far back; head pointed; jaws large with unequal sized canine teeth.

DISTICHODONTIDAE

Nkupe and Chessa : Scales ctenoid and rough; teeth even bicuspid; mouth square; lower jaw closes between lateral plates of upper jaw; adipose fin present.

CYPRINIDAE

Minnows, Yellowfish and Carp : no teeth in jaws; head without scales; mouth protrusable;one or two pairs of simple barbles; dorsal fin with or without spine; no adiose fin.

BAGRIDAE

Rock Catfish : no scales; dorsal fin short; dorsal and pectoral fins with strong spine; three pairs of barbels one each from angle of jaw, two pairs on lower jaw; large adipose fin.

SCHILBEIDAE

Butter Catfish, no scales;dorsal fin short, dorsal and pectoral fins with spine; anal fin long based, caudal fin bent downwards; four pairs of barbels present; adipose small or absent.

AMPHILIDAE

Mountain Catfish : no scales; dorsal fin short; dorsal and pectoral fins without spines; pectoral and pelvic fins large with thickened leading ray and with fine filaments on the edge; three pairs of barbels; adipose fin present.

CLARIDAE

Common Catfish : no scales; head flattened and armoured with boney plates; four pairs of barbels; normaly have coarse sandpaery teeth; dorsal fin elongated, without spine; pectoral fin with spine; anl fin long-based.

MALATERIDAE

Electric Catfish : no scales; no dorsal fin; adipose fin present; gill opening small; three pairs of barbels; capable of generating a powerful electric shock.

MOCHOKIDAE

Squekears and Catlets; no scales; dorsal and pectoral fins with strong spines; three pairs of barbels; barbles on lower jaw are often branched; mouth ventral with teeth in patches or bands on top jaw and in a single row in the bottom jaw; adipose fin present.

CYPRODONTIDAE

Topminnows and Killifish : head and body with scales; mouth upturned; dorsal fin short and far back; caudal fin well rounded; pectoral fin high up on the body.

MUGULIDAE

Mullets : head and body scaled; two dorsal fins, front one with four weak spines; pectoral fins high on the body: Pelvic fins with weak spines; mouth terminal with small teeth.

CENTRACHIDAE

Bass and Bluegill (exotic) : small scales on head and body; mouth large with sharp teeth; dorsal fin in two parts with spines and soft rays; pelvic fin below pectoral fin; single lateral line along body.

CICHLIDAE

Tilapias: scales on head and body; single nostril on each side; dorsal fin continupus with many spines; and few rays; pelvic fin with spine; anal fin usually with 3 spines, split lateral in line.

GOBIDAE

Gobies : two dorsal fins; pelvic fins united to form perching disc; eyes on top of head; caudal fin rounded or pointed.

MASTACEMBELIDAE

Spiny eels : Body elongated; scales minute; head pointed with small fleshy appendage at tip; dorsal fin with many seperate spines; dorsal and anal fins confluent; anal fin with 2 spines; pectoral fins small; no pelvic fins.

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I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Thu Apr 30, 2009 2:04 pm 
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The Papermouth or Silverfish
Papierbek or Silwervis
Barbus mattozi


Family : CYPRINIDAE

Description

This attractive silver coloured fish with orange tinted fins, derives its name from the colour and the membrane visible between the upper and lower jaw, when open. It has a large protrusible mouth and underslung lower jaw. It has 2 to 4 short barbles.

The dorsal fin has a strong serrated spine and the scales have radiate striations.

The eyes are placed close to the top of the head.

This fish reaches a maximum length of about 400 mm and a maximum mass of 1.400 kg.

Biology and Ecology

This predator prefers fairly deep pools below a rocky section where it waits in ambush of any possible prey, being insects, zoo plancton and small fish, they also feed on plant seeds.

These fish migrate upstream after the first good rains of spring or early summer in search of suitable spawning surrounds. They reach puberty at the age of 3 years, and reach the age of 8 to 9 years old.

Are preyed on by Raptors, Otters and Barbel.

Distribution

It is well distributed in the Gwai River in Zimbabwe and the Limpopo River system as well as the seasonal Ngwendu, Shangoni, Nkayeni and Spirowiri waterholes in the Park. Some have also been found in the Shingwedzi River.

Threats

Water polution and drought.

_________________
I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Sat May 02, 2009 9:18 am 
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Polution of our Rivers

Polution was mentioned briefly earlier as a threat to the waters of our world and to the organisms who find refuge in these waters.

Here below is some more details of water polution :

Untouched soil is by nature alkaline or basic having a higher pH. Resulting in the heavy metals deposited in the soil on the land and the silt of our waters remaining stable and undisolved.

Heavy metals include lead, uranium, nickel, cadnium, thallium, arsenic, chrome, mercury, also copper, selenium and zinc.

When acids like sulphuric, nitric, phopsphoric and hydrofluoric acid are released into the waters, the acidic water with a low pH reacts with with the stable heavy metals and form sulphate, nitrate and phosphate salts which dissolve in the water and then affect the organisms living in the waters.

These disolved salts cause excess nutrients in the rivers, streams and lakes, that stimulate plant growth mainly algae and nuisance plants and weeds - eutrophication - the enhanced plant growth reduces dissolved oxygen in the water, when dead plant material decomposes - the low concentration of oxygen a condition called hypoxic then causes other organisms to die.

Apart from the acid disolving the stable metals mentioned above, polution can also come from fertilizers applied to the agricultural lands, golf courses and domestic gardens washed into the rivers during rains, erosion when dissolved nutrients in the soil are washed into the waters and now also untreated or insufficiently treated domestic sewage being discharged into the waters.

The intake of these salts leads to Bioaccumulation - a little at a time then being stored in the tissues of the affected animal, while the animal is healthy, no effects are visible but when it loses condition due to drought or other reasons, the concentration of the ingested salts increases relative to it's body mass and then starts having its negative effect, snowballing as the animal loses more condition due to the increased salts concentration . . . . . . .

Insecticides and pesticides ending up in the water do not kill immediately, but it is a given that due to Bioaccumulation, they will.

Hypoxia in lakes, streams and rivers means an oxygen concentration of less than two parts per million = not enough oxygen to support fish and other aquatic animals. This is caused when excess aquatic growth reduces sunlight penetration into the water, thus affecting the process of photosynthesis ( the production of oxygen ), this decreased amount of oxygen in the water now causes poor habitat for the aquatic animals and plants, now the decreased in dissolved oxygen causes the degradation of the dead plant material which now consumes the little available oxygen left in the water.

Evidence of etrophication has been clearly visible in the Olifants River for many years, leading to the suffocation of crabs, molluscs and many other invertibrates as well as vertibrates like fish which are then in turn taken by otters, birds and crocodiles.

Many metals in the soil are advantageous to man and are consumed daily e.g. copper, selenium, zinc and magnesium in the vegetables and fruit we eat. However they are only advantageous when absorbed as a trace element, they become extremely toxic when absorbed in large/overdose quantities e.g. as in the dissolved salts mentioned.

Oils, lubricants fuels and other waste effectively seals the water surface from the air, limiting oxygen absorbtion by, or oxygen from disolving into, the water, negatively effecting the eco system.These oily substances also clog the oxygen absorbtion mechanisms of the aquatic plant and animals, effectively also suffocating them.

It was recently mentioned that recent tests on water indicated that an increased concentration of antibiotics was found in water - we humans use antibiotics in combatting illness and disease, but we do not use all we pay for, the body excretes a large part of the ingested - into our sewer systems, which then end up in our rivers, which we then again ingest when having a glass of cool refreshing water or a cup of tea or while having a prepared meal. The disease causing organisms then have to mutate in order to survive - causing " stronger and better " antibiotics to be developed to combat the mutating disease causing organisms which are taken and the excess is then again excreted into the sewer system . . . . . . . it never ends, untill one day when it is too late.

Biologists have found fish and frogs where of the males of the species were developing female generative organs, further studies then found that higher than normal estrogen concentrations were present in the waters from which these animals had been taken. This was traced back to the excess estrogen secreted by females of the human species taking birth control pills.

Now today we have a cure or for almost everything, this is just a short term solution, We develop and change and exploit and poison and toxify and mine and indutrialise our little world and nature - in the long run we may find that human action has lead to its own destruction.

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I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Fri May 22, 2009 8:52 am 
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Madagascar Mottled Eel
Geelbontpaling
Anguilla marmorata

Family : ANGUIILIDAE

Description

Freshwater eels breed in the sea in the Indian Ocean propably north of Madagascar. The eggs hatching into transparent larvae called leptocephali, which drift to the shore in the ocean currents, eventually developing into elvers. ( a baby eel 50 - 70 mm in length and approximately 4 mm in diameter ).These elvers enter the estuaries and then migrate long distances to inland rivers where they feed and grow for 10 years or more, the adults then return to the sea to continue their life cycle.

Elvers have a better chance of survival than larger eels as being small they can wriggle their way up and through obstructions

Depending on the turbidity of the water of the habitat the mottled colour varies from olive-yellow with olive-brown mottled in muddy waters, to olive-yelllow with brownish green mottled in clearer water. Larger pecimens are dark on the dorsal surface and have an irridescent silvery to white belly.

These large eels can reach a length of 150 cm and attain a mass of 18 kg.

These predacious fish have great strength and a formidable appearance and when attacked it will defend itself.

Biology and Ecology

This species prefers deep rocky pools. They are generally carniverous and feed on freshwater crabs, fish, frogs, worms and other small aquatic animals.

An eels life approaches it's end when sexual maturity is reached. Maturation is accomplished by changes in appearance, the colour changes to a more silvery and an increased eye size and gonads and in the final stage, atrophy ( deterioration ) of the digestive system. The migration then begins to the spawning area in the depths of the ocean, from which the adults never return.

Distribution

Males generally stay near the sea while the females who may survive for 20 years, move deeper inland.

The perennial rivers of the Park as well and pools of the larger seasonal rivers such as the Mbyamiti are suitable habitat for these interesting fish.

Threats

Water polution caused by domestic, agricultural, industrial and mining waste deposited into the feeder systems, changing the water to a low pH (acidic). Obstruction e.g. walls and weirs built in rivers without ladders prevent these species from moving upstream into suitable habitat.

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I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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 Post subject: Re: The Fishes of the KRUGER NATIONAL PARK
Unread postPosted: Fri May 22, 2009 10:23 am 
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Location: VEREENIGING
African Mottled Eel
Afrikaanse Bontpaling
Anguilla nebulosa labiata


Family : ANGUILLIDAE


Description

The breeding habits are similiar to those of the Madagascar Mottled Eel ( maromorata ), the two species are also often confused.

The mottled pattern is much more bold than that of A. marmorata, it also has a shorter dorsal fin. The colouring of a specimen taken from more muddy waters is much lighter with a yellow background than those taken from the deep rocky pools with clear water, who can be very darkly coloured with a distinctly mottled pattern. Large specimens may have a dark dorsal surface with mottled sides with irridescent silvery white on the belly.

These are large eels with females exceeding 20 kg in mass and 1700 mm. in length.

Biology and Ecology

This species have no real preference to habitat, water temperature is important and they frequent the deep and shallow pools, clear and muddy waters, slow and fast flowing rivers and streams with access to the Indian Ocean.

They feed on worms, crabs and fish.

An eels life approaches it's end when sexual maturity is reached. Maturation is accomplished by changes in appearance, the colour changes to a more silvery and an increased eye size and gonads and in the final stage, atrophy ( deterioration ) of the digestive system. The migration then begins to the spawning area in the depths of the ocean, from which the adults never return.

Distribution

Males have not been found inland but females have been found up to 1600 km inland ( in the Zambezi River ).

They are fairly common all along the east coast and have been found as far south as the Breede River in the Cape.

The African Mottled Eel is not common to the Park, although specimens have been taken from the Crocodile River.

Threats
Water polution caused by domestic, agricultural, industrial and mining waste deposited into the feeder systems, changing the water to a low pH (acidic). Obstruction e.g. walls and weirs built in rivers without ladders prevent these species from moving upstream into suitable habitat.

_________________
I participate because I care - CUSTOS NATURAE
No to Hotels in and commercialization of our National Parks.
No to Legalized Rhino and Lion trade.
Done 144 visits to National Parks.
What a wonderful privilege.


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