[Coral-List] Is there a time limit up to which buoyant weight based growth rates are useful in corals?

Christine Schonberg christine.schonberg at uwa.edu.au
Tue Jan 3 09:41:34 EST 2017

Hi Thomas,

Measuring buoyant weight change in corals in reference to live surface
area is good, because this is also how we measure and standardise total
sponge bioerosion, e.g. in the context of OA. This way data on calcifiers
and bioeroders become more comparable and can also be extrapolated to a
given community if abundances are known. My opinion is that with ongoing
changes in present environments standardisation and normalisation of data
is increasingly important so that we can gain a better understanding where
shifts occur, what are the dominant pathways of change, and how factors
and organisms interact.

I can send our publications as listed below, for the bioerosion context.

Cheers, Christine

Publications using BW to assess sponge bioerosion and re standardisation,
- Schönberg CHL, Fang JKH, Carreiro-Silva M, Tribollet A, Wisshak M (in
press) Bioerosion: the other ocean acidification problem. ICES J Mar Sci.
- Fang JKH, Mason RAB, Schönberg CHL, Hoegh-Guldberg O, Dove S (online
2016) Studying interactions between excavating sponges and massive corals
by the use of hybrid cores. Mar Ecol.
- Schönberg CHL (2015b) Monitoring bioeroding sponges: using rubble,
quadrat or intercept surveys? Biol Bull 228: 137-155.
- Fang JHK, Mello-Athayde MA, Schönberg CHL, Kline DI, Hoegh-Guldberg O,
Dove S (2013) Sponge biomass and bioerosion rates increase under ocean
warming and acidification. Global Change Biol 19: 3581-3591.
- Wisshak M, Schönberg CHL, Form A, Freiwald A (2012) Ocean acidification
accelerates reef bioerosion. PLoS ONE 7: e45124.

Dr. Christine Schönberg

School of Earth and Environment
and Oceans Institute
The University of Western Australia
Crawley, WA 6009

'Apart from values and
ethics, which I have tried to live by, the legacy I would like to leave
is a very simple one - that I have always stood up for what I consider to
the right thing, and I have tried to be as fair and equitable as I could
be.' Ratan Tata

On 3/01/2017 6:11 pm, "coral-list-bounces at coral.aoml.noaa.gov on behalf of
Thomas Krueger" <coral-list-bounces at coral.aoml.noaa.gov on behalf of
thomas.krueger at epfl.ch> wrote:

>Happy New Year to everyone and thanks for all the comments and
>suggestions to my question. Since a number of people were interested in
>the answer to this issue, I will do my best to give you the short
>version of an answer. Langdon, Gattuso & Anderson 2010 (Chapter 13 in
>Riebesell et al 2010 Guide to best practices for ocean acidification
>research and  data reporting) recommends to measure buoyant weight as
>the ratio of the change in dry skeletal weight and the number of days
>between weighing. While this is certainly a good approximation for
>weight increments especially on small time scales or small weight
>increments, one does inevitably run into the problems mentioned in my
>original post as highlighted by Goreau & Goreau 1960 (Biological
>Bulletin 118 (3) 419-429) and Kawaguti 1941 (Palao Trop. Biol. Sta. 2:
>309-317). I would like to thank Prof Rolf Bak for sending me his paper
>(Bak, R.P.M. 1976. The growth of coral colonies and the importance of
>crustose coralline algae and burrowing sponges in relation with
>carbonate accumulation. Neth. J. Sea Res. 10: 285-337) that provides
>repeated buoyant weight measurements from different corals and nicely
>illustrates this non-linear weight gain over time (Figs. 2-5 in the
>publication). As mentioned in my original post, the problem with the
>buoyant weight technique is that it is not normalized to any other
>metrics. The data of Bak 1976 clearly show that one should simply apply
>an exponential growth formulae on repeated weight measurements rather
>than a linear one to obtain a mg weight increment per day value. Prof
>Bak writes in this regard: "Comparisons of growth should be based on the
>production per unit of living surface area, or when data on living
>surface area are lacking on exponential growth formulae". For the
>practical application of buoyant weight measurements this means that one
>should perform occasional weighing over the period of interest and fit
>an exponential equation to derive a daily growth rate (as absolute
>weight increment per day), rather than dividing the difference between
>initial and end weight by the number of days. Again, for some corals
>that mainly grow along defined axes (e.g, vertical linear extension in
>digitate growth forms) the difference between the derived growth rates
>from a linear or exponential growth formula will probably be very small,
>but especially for massive and foliaceous corals were surface areas
>increase across the colony, the effects will be much bigger and warrant
>the use of the correct formula. If you are interested in reading the Bak
>1976 publication and do not have online access to it, you can email me
>or Prof Bak directly
>Thanks for all the feedback.
>*Thomas Krueger */Postdoctoral Researcher/
>Laboratory for Biological Geochemistry | École polytechnique fédérale de
>Lausanne (EPFL)
>*P*: (+41) 21 69 38039
>Coral-List mailing list
>Coral-List at coral.aoml.noaa.gov

More information about the Coral-List mailing list