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Mangrove & Saltmarsh responses to Climate Change

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                                                    <<<Straight to the MangroveWatch Species Record Database >>>AMSN Home

AMSN logoMangroveWatchDid you know that mangroves are already responding to climate change?

It is only a question of how they are responding, not if! This section explains what to look for, and how to spot your own examples of change. By uploading images and notes, you will be helping measure the effects of climate change. 

To start, let's look at TEMPERATURE! You know it is rising, remember the 'hockey stick' graphs. How are plants affected? Their responses are often obscured by daily, seasonal/annual, and longer term fluctuations (like el nino years). But, did you know that the timing of peak flowering and fruiting of mangrove plants is affected by temperature? There are some interesting observations to consider. 

Phenology Flyer                                                               <<<Download the Phenology Flyer with Summary Instructions>>>

Latitudinal Shifts in Flowering and Propagule Maturation of Avicennia marina

AM Phenol graphFor the Grey Mangrove, Avicennia marina, timing of peak flowering and propagule maturation (fruiting) are directly linked to daily temperatures. The phenology graph (to the right) shows how peak flowering and fruiting events had occurred in sites around Australia back in 1982-83. 

Reference:  Duke, N.C. 1990.  Phenological trends with latitude in the mangrove tree Avicennia marinaJournal of Ecology 78: 113-133. 

The graph shows degrees of Latitude (N & S) and calendar months. Degrees of Latitude may be taken as a proxy for temperature. Notice how flowering and propagule maturation (red lines) gets later where temperatures are cooler, and that between N & S hemispheres, the timing was six months different to sites at similar latitudes. 

The initiation of these events begins at an earlier time matching dates when daylength becomes greater than 12 hours (green line). After this date, the period (number of days) to flowering and then propagule maturation were determined by adding up the daily mean temperatures, as degree days. And, as it happened, this means the event dates were predictable. 

The following three equations describe how this worked, based on average mean daily air temperatures (Tm):

a) DAYS from Initiation to flowering = 888.6 + (-55.86 (Tm)) + 1.010 (Tm)2

b) DAYS from Flowering to propagule maturation = 738.9 + (-43.92 (Tm)) + 0.725 (Tm)2

c) DAYS from Initiation to propagule maturation = 1518.4 + (-89.63 (Tm)) + 1.512 (Tm)2

AM PhenTemp

From these relationships, it was deduced that as temperatures might rise in any location, then flowering and propagule maturation dates would be expected to become earlier and earlier (shorter development period) at that place. The graphs to the left show more of the 1982-83 data.

Has the timing of flowering and propagule maturation (fruiting) changed in your local mangroves?

We have noticed that fruiting of Grey Mangrove appears much earlier this year around Brisbane and Moreton Bay! What are these flowering and fruiting dates doing in your area?

We are checking the temperatures for this year to see how much hotter it is. We would like to find out if you are noticing the same thing! 

Further Reading: 

Duke, N.C. 1988.  Phenologies and litter fall of two mangrove trees, Sonneratia alba Sm. and S. caseolaris (L.) Engl., and their putative hybrid, S. X gulngai N.C. Duke.  Australian J. Botany 36: 473-482.

Duke, N. C. 2001. Mangrove phenologies and the factors influencing them in the Australasian region, pp. 217-233. In L. D. de Lacerda (ed.), Mangrove Ecosystems: Function and Management. Berlin, Springer-Verlag. 292 pages.

Similar patterns of flowering and fruiting shifts in other Mangrove Plants

MangroveiD AppCheck out the World Mangrove iD app, to see similar phenology graphs for other mangrove plants, showing how each has comparable, distinct flowering and fruiting trends with latitude - and therefore temperature!

To learn more about all mangrove species, check out the app version on your preferred smart device:
                                Android                                           Apple 

You can also use the app to send in your pictures, location and data! 

Are the dates of flowering and propagule maturation changing?

Australasia MapThe simple answer is, we are not sure! Are our deductions/observations above correct for Grey Mangrove, Avicennia marina? To prove it either way, we need many more observations of when flowering and fruiting occurs in lots of places around the country, and elsewhere. You can help by taking a photo and making notes about your local mangroves or saltmarsh plants each month, each year, or whenever.

And, while you are there, why not learn about another different species each time in your uploaded records for the MangroveWatch database. It might take awhile to compile enough records to give a definitive answer, but only in this way, we will be able to get the evidence needed to settle this question once and for all.

We need your records uploaded to work out how mangrove & saltmarsh plants are responding to climate change.

Phenology FlyerINSTRUCTIONS                                        <<<Download the Phenology Flyer with Summary Instructions>>>

Recording your Observations               <<<Link to the MangroveWatch Species Record Database >>>


Hold the leafy shoot with flowers or propagules in your hand and take the image. make sure you show some leaves as well as any of the buds, flowers or propagules present.


Record your observations, noting the following information, if you can. 

Species ID, Date, Location, Coordinates, Floral Status <USE the shorthand CODES if you like, images shown below right: nA - no flowering bits, Bp - bud primordia, Ba - immature buds, Bb - mature buds, I - flowers, Faa - very immature fruits, Fa - immature fruits, Fb - mature fruits, Ha - immature hypocotyls, Hb - mature hypocotyls, Fex - expended fruits, nL - new leaves, nS - new branch shoots>, and Any Other Notes (like Trunk Stem Base).


a. Upload Site. Go to the site using the URL for uploading to the MangroveWatch Species Record database  

b. If you have not already done so, you will need to Sign In.  Use the link on the word ‘here’. You will be asked to type in the numbers you see as a security step. Fill in your Account Details. You will need to add something in each field. <tip: keep your username and password simple and easy to remember>

c. Registered. Once registered, enter your Username and Password.

d. Log In. Once you are logged on, use the ‘Add a Sighting’ tab, and select ‘Single Mangrove Species Record’. A map will be displayed, and below there will be a number of data fields.

e. Map Location. For recording your location coordinates you have two options. One is to use the map <go to (f)>, and the other is to type your coordinates into the two fields, after selecting a species name <go to (g)>.

f. Using the map. First locate your sighting on the map. You must place a marker on the map using your cursor, and then zoom in until you have sufficient resolution to move the cursor as near to your collection site as possible. Relocating the marker is done by placing the cursor over the marker, and as you hold your selection, you can drag the marker to the preferred location <go to (h)>.

g. Species. Type in the first three (3) letters of the genus name of the mangrove species being observed. Example: type in ‘Avi’ and a list of names of all Avicennia species will be displayed. Select the one that best identifies the one you have. If you only know it as Avicennia, that will do. Your photos and location will help an expert to work out the species name later. 

h. Latitude & Longitude. If the two coordinate fields are filled skip to Date & Time <go to (i)>, or add your coordinates (these must be decimal degrees, not degrees, minutes and seconds), then you can simply type these into the appropriate fields below. Use ‘Hide Map’ to clear the screen for a clear view of the data fields.  Note that Latitude will be negative for sites in the southern hemisphere. And, for Longitude this will be negative for sites in the western hemisphere. In these situations place a ‘-‘ minus sign before the digits. Example: Latitude = -26.096255; Longitude = 153.061523.

i. Date & Time. These two fields should be filled in automatically, but you may want to edit them to better match the time and date when you visited the site.

j. Notes. This field is for your extra notes to back up your photos and location. Your observations about flowering and propagule stages, and some other observations are listed in the Multiple Choice Observations <go to (n) below, after uploading any photos you have in (k), (l) & (m)>. 

k. Image File (Flowers/Fruit/Propagule). Use ‘Choose File’ to locate the image file you would like to upload to verify your observation. This is the place to upload an image showing the reproductive phase (flowering or fruiting stage) of this species, listed in your Multiple Choice Observations below (n).

l. Image File (Albino Fex). Use ‘Choose File’ to locate the image file you would like to upload to verify your observation. This is the place to lodge your photo of the Albino variety of this species (try to locate the parent source tree for the location!), and noted also in your Multiple Choice Observations below (n).

m. Image File (Large Trunk Stem Base). Use ‘Choose File’ to locate the image file you would like to upload to verify your observation. This is your chance to stake a claim for the largest tree of this species (or just a large tree!), and noted in your Multiple Choice Observations below (n).

n. Multiple Choice Observations. 2 above, and the images above right). Use the associated shorthand codes to make things easier, like: nA, Bp, Ba, Bb, I, Faa, Fa, Fb, Ha, Hb, Fex, nL, nS, and/or Large Trunk Stem Base.

o. Submit. Remember to select Submit so your record will be saved.


Select ‘View Data’ to look at either your data (‘My Data’), or all data (‘All Data’).  You can refine the selection displayed by checking the various categories on the left side of the page. And, further by using the Search field. You can also toggle between the data fields, Images and Map locations. And, you might like to download your selected data from the database from time to time.