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Sosiale wetenskappe: aardrykskunde

Graad 8

Natuurlike hulpbronne

Module 9

Mariene bronne en die kus

Mariene Bronne

  • Die oseane bedek meer as twee derdes van die aardoppervlakte en speel ‘n sleutelrol in die hidrologiese siklus, die chemiese werking van die atmosfeer en die vorming van die klimaat en weer. Hoewel die oseane groot is, is hul eintlike biologiese rykdom gekonsentreer langs kuslyne, by riviermondings en op die relatief smal kontinentale banke tot op ‘n diepte van ongeveer 200 m. Hierdie gebied bevat die groot visvelde wat 80 persent van die wêreld se vis oplewer en een van die vernaamste voedselbronne vir miljoene mense is. Suid-Afrika is die wêreld se 24ste grootste visprodusent en meer as 90 persent van die jaarlikse vangs kom van die hoogs produktiewe koue waters van die Weskus.
  • Tot dusver is daar nog weinig formele pogings aangewend om die see veeldoenig te benut. Vroeëre en bestaande regulasies is hoofsaaklik gemik op die kommersiële ontginning van mariene bronne. Nie-volhoubare visvangste hou die grootste bedreiging in vir lewende mariene bronne. Baie van hierdie visvelde is in die verlede oorontgin en sommige visstapels, soos die sardyne langs die Namibiese kus, het nog nie herstel nie. In ‘n poging om visbronne volhoubaar wyse te benut, het die Suid-Afrikaanse owerhede ‘n kwotastelsel binne ‘n Totale Toelaatbare Vangs (TTV) vasgestel vir kommersiële spesies, aangevul met geslote seisoene en groottebeperkings.
  • Onder Suid-Afrika se ou bestel is gemeenskappe se tradisionele toegang tot mariene bronne geleidelik van hulle ontneem, deurdat voorkeur gegee is aan groter maatskappye wat deur vermoënde aandeelhouers beheer is.

  • Enkele jare gelede het die Wes-Kaapse regering besluit om d.m.v. wetgewing viskwotas in te stel. Dit het tot groot teenkanting onder verskillende gemeenskappe gelei. Hier volg twee van talle response in die plaaslike koerante.

Vis op drumpel van uitwissing

Ek lees met skok in Die Burger van 18 April van die ineenstorting van lynvis in ons waters. Agt lyn-visspesies word tans vinniger gevang as wat hulle kan teel.

Volgens die verslag van dr. Marc Griffiths van Mariene en Kusbestuur sal lisensiehouers verminder moet word om die visbedryf te red.

Die verslag meld dat galjoen, silwer-kabeljou, witsteenbras, witstompneus en donkerkabeljou vinniger gevang word as wat hulle kan teel en dat die elf reeds oorbenut is. Die dageraad het glo al feitlik verdwyn.

Om die visbronne van totale uitwissing te red sal strenger maatreëls toegepas moet word.

Opofferinge sal deur die rots- en strandhengelaars sowel as die strandnet- en treiler-eienaars gedoen moet word.

Verder sal die Regering ernstig daaraan moet dink om meer wetstoepassers aan te stel om die regulasies op die bewaring van Mariene en Kusbestuur afdwingbaar te maak, en dit behoorlik toe te pas.

Buitelandse vistreilers sal verbied moet word om binne 200 km gebiedswaters van Suid-Afrika vis te vang, en geen viskwotas moet aan hulle toegestaan word nie.

Strandnet-eienaars moet vir minstens twee jaar verbied word. Indien hulle wel toegelaat word om vis langs die kus te vang, moet hul nette drasties na 100 m verkort word, sonder ‘n sak in die net. Strandnette roei talle ondermaat-visse uit.

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Aardrykskunde graad 8. OpenStax CNX. Sep 11, 2009 Download for free at http://cnx.org/content/col11035/1.1
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