Saltvandsforum.dk

“…Coral reef communities are stable ecosystems that have existed in a state of near-equilibrium for millions of years, arising largely as a result of long term and diverse competitive evolutionary adjustments under benign environmental conditions….”

if stability means a lack of variation. It simply and patently is not stable. In fact of shallow water marine ecosystems throughout the world, coral reefs are amongst the most variable in terms of day-to-day temperature fluctuations as well as fluctuations in other parameters. If an aquarist manages some success without natural variations, they are managing those success in spite of the lack of variability, not because of it.

Surface Water Temperatures for Belize City, Belize, 1964-1971.
............................Average..............Maximum
...........................F............C.........F.........C
January...............79.2.......26.2.....84.2......29.0
February..............80.2......26.8......84.2......29.0
March..................82.4......28.0......89.6......32.0
April....................84.9......29.4......91.4......33.0
May....................86.7......30.4......91.4......33.0
June................... 86.2......30.1......91.4......33.0
July....................85.6......29.8......89.6......32.0
August................87.1......30.6......89.6......32.0
September...........86.2......30.1......91.4......33.0
October..............84.9.......29.4......89.6......32.0
November............81.3......27.4......87.8......31.0
December............79.9......26.6......84.2......29.0

Meller skrev:
men rart at se man ikke burde koge akvariet af selv hvis det er 30 grader

Meller skrev:Der var et burde indblandet, da jeg godt ved det jo er afhængelig af hvor korallerne kommer fra men kan man ikke tilvænne dem en højere temperatur hvis vi snakker flere måneder?

Meller skrev:okay, er der en måde man kan genkende disse mere resistent zoochanteller? altså er den udviklet i bestemte koral typer ?

AndersGS skrev:Jeg tror som det også fremgår af tabellen, ikke at de høje temperaturer er det der dræber, men derimod de hurtige ændringer.

I naturen tager det fx. 1 måned at stige 1 grad. I akvariet er det måske fra kl 12-17 på én dag at det stiger 1 grad.

Meller skrev:okay, er der en måde man kan genkende disse mere resistent zoochanteller? altså er den udviklet i bestemte koral typer ?

Infectious bacteria of the species Vibrio shiloi are the bleaching agent of Oculina patagonica in the Mediterranean Sea, causing this effect by attacking the zooxanthellae.[35][36][37] V. shiloi is infectious only during warm periods. Elevated temperature increases the virulence of V. shiloi, which then become able to adhere to a beta-galactoside-containing receptor in the surface mucus of the host coral.[36][38] V. shiloi then penetrates the coral's epidermis, multiplies, and produces both heat-stable and heat-sensitive toxins, which affect zooxanthellae by inhibiting photosynthesis and causing lysis.

During the summer of 2003, coral reefs in the Mediterranean Sea appeared to gain resistance to the pathogen, and further infection was not observed.[39] The main hypothesis for the emerged resistance is the presence of symbiotic communities of protective bacteria living in the corals. The bacterial species capable of lysing V. shiloi had not been identified as of 2011.

A new species of bacteria, Vibrio corallyticus, was consistently found in the tissues of the bleached Pocillopora at a level that already fulfills the first of Koch's postulates. The virulence is even more amazing. At 23° C, there are no visible signs of disease. At 25° C, bleaching occurs. At 27° C, there is rapid tissue lysis. A virulence factor is being produced by this bacteria that correlates extremely well with the temperatures commonly cited as causing coral bleaching. Furthermore, Rosenberg describes the bleaching as spreading; a characteristic seen all too often by both field observers and aquarists.

engelquist skrev:

AndersGS skrev:Jeg tror som det også fremgår af tabellen, ikke at de høje temperaturer er det der dræber, men derimod de hurtige ændringer.

I naturen tager det fx. 1 måned at stige 1 grad. I akvariet er det måske fra kl 12-17 på én dag at det stiger 1 grad.

Du rammer den lige i øjet- stabilitet er stadig mantraet..

The most rapid growth of most corals is generally around 27°C to 29°C (80.6°F to 84.2°F) (Barnes et al., 1995; Clausen and Roth, 1975; Weber and White 1976; Coles and Jokiel, 1977, 1978; Highsmith, 1979a, b; Highsmith, et al., 1983). Subtracting 10°C from this range gives a temperature range of 17°C to 19°C (62.6°F to 66.2°F). The lower temperature that is typically considered to be acceptable for coral reef formation is 20°C or 68°F, which is close to the value that would be expected by using the Q 10 value. In essence, the Q 10 value may be used to approximate the lower limit of most coral reef distributions; however, in reality relatively few coral species persist at temperatures much below 24°C (75.2°F). Certainly, there are coral reefs found at these cooler temperatures, but they contain a much reduced array of cold tolerant (for a coral reef) animals compared to warmer reefs.

Interestingly, while the lower limit of most corals may be determined by examination of the Q 10 term, the converse is not true. Natural selection seems to have shaped corals, and many other coral reef organisms, to have an optimal temperature near the upper end of their normal acceptable range. This makes biological sense in that the evolutionary process works on the production of offspring. As far as the evolutionary process is concerned, the organism that produces the most viable descendents wins the evolutionary lottery. At the higher metabolic rates generated under higher temperatures, more eggs and sperm can be produced and the more potential offspring can be generated. But these are organisms are on the edge, at temperatures only a few degrees above the optimal for most coral reef animals, enzymatic reactions begin to uncouple and the organisms start to show signs of severe distress. So, while one might expect from the Q 10 values that the upper limits for most coral reef animals would be in the range of 40°C (104°F), it appears that the natural upper limit for reef organisms appears to be prolonged exposure to temperatures above 33 ° C (92 ° F), and is naturally reached in some areas in the Persian Gulf, or in shallow water areas in atoll lagoons (Brandon 1973; Glynn and D'Croz, 1990; Fitt and Warner, 1995; Lesser, 1996).

PederP skrev:Temperatur påvirker jo også alle mulige mikroorganismer. Stofskiftet hos nogen bliver kraftigt forøget, andre organismer vil sikkert ikke finde det optimalt og dermed må de vige pladsen.
Eftersom baljen ikke har revets vandskifte, så mener jeg at det er her truslen for at slå det hele ihjel kommer fra.
Så selv om korallerne kan klare mosten, så er det ikke sikkert baljen forbliver et sundt opholdssted i varmen.

engelquist skrev:jeg kommer lige til at tænke på dr2's tema-lørdag om Great Barrier Reef- der så man store dele af revet blive blotte til solens stråler og vandet i de små vandpytter nåede nærmest kogepunktet, inden tidevandet vendte- med frisk og køligt vand fra de store dybder i Stillehavet.... det er da temperatursvingninger der vil noget?
Jeg tror at vi ville gøre vores baljer en stor tjeneste ved at skifte meget mere vand end vi gør nu- et vandskifte på 50-60 % ville svare til et godt tidevandsskifte- bakteriekulturen lever jo i sten og bundlag, så det skal nok overleve- men til forskel fra vandet ved revet- er vores vand MEGET rigt på bakterier...
Så en lidt provokerende tanke: UV filter 24/7 (for mere sterilt vand, som ved revet)og et ugentlig vandskifte på +50 % ?

Meller skrev:Ole for lige at få nogle størrelser på så fandt jeg lige det her, hvor han skriver hvor mange liter han mener de forskellige ting bør være på

Hvam skrev:

engelquist skrev:

AndersGS skrev:Jeg tror som det også fremgår af tabellen, ikke at de høje temperaturer er det der dræber, men derimod de hurtige ændringer.

I naturen tager det fx. 1 måned at stige 1 grad. I akvariet er det måske fra kl 12-17 på én dag at det stiger 1 grad.

Du rammer den lige i øjet- stabilitet er stadig mantraet..

idet er mere teroi end praktis eks steg vandet i dk fra 11 til 15 c i sidste.weekend. jeg har også set det ved rødehavet hvor temp steg fra 28 til 31c på 5 dage. Så solen har mere magt end vi tror.

PoulD skrev:Min computer har logget temperatursvingninger på helt op til 4 gr. C over 48 minutter ved et lavt dyk (6-8m) i Rødehavet. Det var så man ganske tydeligt, selv i en heldragt, kunne mærke kolde strømme hist og her

PoulD skrev:Min computer har logget temperatursvingninger på helt op til 4 gr. C over 48 minutter ved et lavt dyk (6-8m) i Rødehavet. Det var så man ganske tydeligt, selv i en heldragt, kunne mærke kolde strømme hist og her

nbd skrev:Uha - med 33 grader bør man koble en megakøler på revet

ole. skrev:

PederP skrev:Temperatur påvirker jo også alle mulige mikroorganismer. Stofskiftet hos nogen bliver kraftigt forøget, andre organismer vil sikkert ikke finde det optimalt og dermed må de vige pladsen.
Eftersom baljen ikke har revets vandskifte, så mener jeg at det er her truslen for at slå det hele ihjel kommer fra.
Så selv om korallerne kan klare mosten, så er det ikke sikkert baljen forbliver et sundt opholdssted i varmen.

selv om koraller bliver blege er de jo ikke døde,de lever skam dog gevaldig stresset,jeg læste netop en tese om at det var for at gøre plads til andre slags zooxantheller at de smider dem de har/bliver afblegt