Biomass and production of the epiphytes on the leaves of Cymodocea nodosa in the Canary Islands

The biomass and production of the epiphytic community on the leaves of Cymo docea nodosa were measured during an annual cycle, from June 1991 to May 19 92. The biomass of the epiphytes always increased with the age of the leaf in each shoot throughout the year. The mean annual biomass of epiphytes was 52.6 g dw m(-2) of leaf, with a maximum of 109 g dw m(-2) of leaf in Novem ber and a minimum of 33 g dw m(-2) of leaf in March. The biomass of the epi phytes was always lower than the biomass of the leaves on which they were g rowing, except in November. The epiphytic biomass varied from 124.1 g dw m( -2) meadow area in winter to 29.7 g dw m(-2) in spring. The mean annual con tribution of the epiphytes to the total epigean biomass of the meadows was 31%, with the highest contribution of 34-57% in autumn-winter and the lowes t one of 17-28% in spring-summer. The annual production of the epiphytes by shoot area was 453 mg dw year(-1) and the annual production of this epiphy tic community per m(2) of meadow was 625 g dw year. The mean production of the epiphytes was also estimated over the year. Two maxima were detected, o ne in winter of 90 mug dw cm(-2) day(-1), mainly due to the longest life-ti me of the leaves in these months (up to 90 days), and the other in late spr ing-early summer of 86 mug dw cm(-2) day(-1) because of the high contributi on of seasonal epiphytes as well as the highest accumulation of biomass of epiphytes per day. In March and April, the minimum value of 38 mug dw cm(-2 ) day(-1) is directly related to the shortest life-time of the leaves in th ese months (up to 45 days). In general. the epiphytic flora on the leaves o f the warm temperate seagrass Cymodocea nodosa showed biomass and productiv ity tendencies comparable to those known for other temperate and tropical s eagrasses.