Mangroves are thought to be extremely susceptible to climate change via sea level rise. Changes in storm intensity and rise in temperatures, along with human freshwater reductions etc. Over recent years, mangroves have been noticed to migrate northwards along US coastlines and southwards in Australia; thought to be so on account of rising temperatures. But what might happen to them in the tropics under higher temperatures?
Are there typical species which are showing sensitivity towards temperature? We have quiet successfully planted mangroves in Kuwait and there are large mangroves plantation in UAE. Here the sea water temperature is between 13-36 oC and ambient 0 - 55 oC. Mangroves have shown considerable resilience and are growing steadily also the salanity is 1% higher than global oceans.
Temperature changes would likely increase rates of photosynthesis, respiration, growth, and reproduction in mangroves as well as lead to alteration in community composition, floral and faunal diversity upto a certain temperature range (33C. see the references below:
Cheeseman, J.M. (1994). Depressions of photosynthesis in mangrove canopies. In: Baker, N.R., Bowyer, J.R. (Eds.), Photoinhibition of Photosynthesis: From Molecular Mechanisms to the Field. BIOS, Oxford, pp. 377-389.
Peter Saenger (2002). Chapter- Physico-chemical Factors and Mangrove Performance . in in Mangrove Ecology, Silviculture and Conservation
Thank you all for sharing your perspectives and links. It is very interesting to hear about mangroves in Kuwait where ambient temperatures routinely cross 40-45 degrees. Is that mainly Avicennia marina ? I agree it is very likely that the community composition of mangroves could change.
Surface water temperature or air temperature may not have real impact on growth and development in Godavari mangroves ( second largest mangroves in India). But salinity play an important role in the shaping the mangroves. As I observed in some areas where fresh water flow is minimum, there stunted plants are present. Further in the soil more than 50% sand particles are present, that afftect the growth of the mangroves. I am workiing on these ecosystems since 1985, besides all these, human actitivities such as industilization is main reason for declining the ecosystems than the cilmate change,.
Geddada, that is a very good point regarding salinity. In the Florida Everglades where i have worked, there are dwarf mangroves in areas with hypersaline water ( > 45-50 ppt). Increasing freshwater withdrawals and decreasing freshwater inflows into estuaries pose further threats. Are you aware of any work done on estimating minimum freshwater flows necessary in the Godavari and other rivers to sustain mangrove communities ( and estuarine ecosystems)? Thank you for you suggestions.
yes Dr Amartya, in the recent years, water inflow towards the seas is reduced due shortage of rainfall and water utilized by the agriculture sector is increased. Now a days Near river mouth salinty is in between 28 to 32 ppt during winter and more saline conditions were observed in summer months. Mangroves are basically classified into true mangroves, associated mangroves and halophytes. Associated mangroves are present where fresh water flow is more and more saline conditions in the waters promote the growth of halophytes and further stunted growth of the true mangroves. I am attaching one photograph of the stunted Avicenia officinalis for information. Thank you
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