ABSTRACT. The photosynthetic c h a t e Mesodinium rubrum is a common component of the plankton in estuarine, coastal and offshore areas. Unusually high photosynthetic rates [ 2 10 pghave been measured during vlsible blooms (red-waters) of this species, but llttle data were available on photosynthesis by Mesodmium during more routine conditions. We used single cell techniques to measure chlorophyll content and rates of photosynthesis in Mesodinium (16 to 18 X 21 to 22 pm in size) that were part of mixed-species phytoplankton assemblages in small estuaries and salt ponds. The carbon:chlorophyll a (wt:wt) ratio for Mesodinium ranged from 47 to 78. Light-saturated rates of photosynthesis ranged from 13 to 88 pg C cell-' h-' 11.8 to 8.6 pg C (pg chl a)-' h-']. These speciesspecific assimilation ratios were within the mid-range reported for community measurements made during Mesodinium red-waters and within the range reported for phytoplankton. Ik values for Mesodiniurn were 2-275 pE m-' S-' in all experiments. At saturating irradiance, carbon fixation ranged up to ca 14 % of body C h-' In our incubations, Mesodinium accounted for from < 1 to 2-70 % of the community primary production in surface water samples although at no time during our studies did it cause red-waters.

The compressive strength and persistence of protein foams produced from extracts of legume leaves were measured. The presence of foliar proanthocyanidin (PA, condensed tannin) in species such as Onobrychis and Lotus correlated with foams of negligible compressive strength and persistence and also with a reputation for bloat safety in the field. PA purified from forage legume leaves significantly decreased the compressive strength of protein foams produced from purified red clover leaf protein. The decrease in the compressive strength was related to the concentration of added PA in a dose-dependent manner. A ratio of PA to protein of 0 . 1 reduced the compressive strength by approximately half relative to the strength of the PA-free control. Purified PAS with different chemical structures had similar effects on the compressive strength of protein foams. The significance of these observations to pasture bloat and forage legume improvement is discussed.

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