Abstract

The biomass and production of the epiphytic community on the leaves of Cymodocea nodosa were measured during an annual cycle, from June 1991 to May 1992. 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 November and a minimum of 33 g dw m⁻² of leaf in March. The biomass of the epiphytes was always lower than the biomass of the leaves on which they were growing, 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 contribution 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 lowest 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 epiphytic community per m² of meadow was 625 g dw year⁻¹. The mean production of the epiphytes was also estimated over the year. Two maxima were detected, one in winter of 90 μg dw cm⁻² day⁻¹, mainly due to the longest life-time of the leaves in these months (up to 90 days), and the other in late spring-early summer of 86 μg dw cm⁻² day⁻¹ because of the high contribution of seasonal epiphytes as well as the highest accumulation of biomass of epiphytes per day. In March and April, the minimum value of 38 mg dw cm⁻² day⁻¹ is directly related to the shortest life-time of the leaves in these months (up to 45 days). In general, the epiphytic flora on the leaves of the warm temperate seagrass Cymodocea nodosa showed biomass and productivity tendencies comparable to those known for other temperate and tropical seagrasses.