Hi!

Here some paper on your topic/

Best wishes,

Tatiana

http://www.chesapeake.org/stac/downloads/habitat%20STAC/lee%20et%20al%202007%20JEMBE.pdf

http://repository.tudelft.nl/assets/uuid:4add84f0-8e89-4da4-9e93-c0c2facffc0b/SPATIAL_VARIATION_AND_SEASONALITY_IN_GROWTH_AND_REPRODUCTION_OF_ENHALUS_ACOROIDES.PDF

http://www.publish.csiro.au/?paper=MF96106

http://link.springer.com/article/10.1007/s00227-008-1064-2

I published a paper on how intertidal enhalus was impacted by solar radiation that also discusses temperature impacts. Might be worth a look? http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034133

High temperature means high total incoming radiation, also high UV radiation, which can inhibit  photosynthesis in turn growth of the   aquatic plants including sea grass. It can be experimentally tested under field and laboratory condition  for any concerned  aquatic plant. See also the paper published in Limnology and Oceanography.  Link is given below.  

http://aslo.net/lo/toc/vol_41/issue_2/0271.pdf