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Genetic affiliation, nuclear DNA content, and gamete functioning were examined in small salt marsh Fucus from three localities in western Ireland. Individuals with small and dioecious receptacles were found at all localities, but production of germlings was only evident from those at Locality 1. Here, the Fucus vegetation formed a morphological cline from F. vesiculosus with bladders in the mid-intertidal to small Fucus individuals lacking bladders in the salt marsh of the upper intertidal. Measurements of nuclear DNA content ranged from 1-1.8 pg at this locality, with the F. vesiculosus individuals in the lower range. At the two other localities, the small salt marsh Fucus formed distinct morphological entities. Microsatellite analyses revealed that the small salt marsh Fucus individuals from Locality 2 were derived mainly from F. vesiculosus, whereas those from Locality 3 were hybrids between F. vesiculosus and F. spiralis with greatest affiliation to F. spiralis. While the small salt marsh Fucus forms from Locality 2 had high nuclear DNA content (ca. 4 pg) and were probably octoploids, the small salt marsh Fucus from Locality 3 formed two groups: one with high (3.9-4.6 pg) and one with low (1.5-1.9 pg) nuclear DNA content. Nuclear DNA content measured in individuals from Locality 3 varied between 1.1-2.8 pg in F. vesiculosus and 2-3.5 pg in F. spiralis, and showed a more or less stepwise increase in both species, consistent with polyploidy. We hypothesize that the small salt marsh Fucus forms originate from genome size changes in the parental taxa.

Caulerpa species are marine green algae, which often act as invasive species with rapid clonal proliferation when growing outside their native biogeographical borders. Despite many publications on the genetics and ecology of Caulerpa species, their life history and ploidy levels are still to be resolved and are the subject of large controversy. While some authors claimed that the thallus found in nature has a haplodiplobiontic life cycle with heteromorphic alternation of generations, other authors claimed a diploid or haploid life cycle with only one generation involved. DAPI-staining with image analysis and microspectrophotometry were used to estimate relative nuclear DNA contents in three species of Caulerpa from the Mediterranean, at individual, population and species levels. Results show that ploidy levels and genome size vary in these three Caulerpa species, with a reduction in genome size for the invasive ones. Caulerpa species in the Mediterranean are polyploids in different life history phases; all sampled C. taxifolia and C. racemosa var. cylindracea were in haplophasic phase, but in C. prolifera, the native species, individuals were found in both diplophasic and haplophasic phases. Different levels of endopolyploidy were found in both C. prolifera and C. racemosa var. cylindracea. Life history is elucidated for the Mediterranean C. prolifera and it is hypothesized that haplophasic dominance in C. racemosa var. cylindracea and C. taxifolia is a beneficial trait for their invasive strategies.

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SUMMARY: The first comprehensive study of the marine algal flora of Namibia including descriptions and illustrations of most species is presented. The main objective of this work is to report a flora that, until now, has scarcely been studied. The work compiles all the available information on the marine benthic flora of Namibia and provides new data about it composition and biogeography, as well as detailed descriptions and remarks of most of its species. The samples on which this study is based were collected between 1986 and 1989 in the eulittoral and the upper sublittoral zones of the north half of the Namibian coast. According to the present data, the marine benthic flora of Namibia comprises 196 taxa (147 Rhodophyceae, 20 Phaeophyceae, 15 Ulvophyceae, 6 Cladophorophyceae and 8 Bryopsidophyceae), 21 of which has not been recorded from this coasts. This temperate flora is mainly characterized by a low number of species, a low proportion of Phaeophyceae and a high degree of endemism. Concerning the species number, the flora is quite poor due to both the scarce availability of colonizable substratum and the low diversity of habitats. On the other hand, the low proportion of Phaeophyceae is the reason for which the R/P and (R+C)/P ratios take disproportionately high values and so they are not useful in this geographical area. As regards the degree of endemism, the marine benthic flora of Namibia includes quite a high number of taxa endemic to southern Africa (55 taxa; 28.1% of the flora); 25 of these 55 taxa (12.8% of the flora) are endemic to the biogeographic Benguela Marine Province and only Acrosorium cincinnatum is endemic to the Namibian coasts.Key words: Namibia, marine algae, morphology and anatomy, distribution, biogeography, taxonomy, check-list. RESUMEN: ALGAS BENTÓNICAS MARINAS DE NAMIBIA. -Este trabajo recoge toda la información existente hasta el momento sobre la flora bentónica marina de Namibia y proporciona nuevos datos sobre su composición y biogeografía, además de descripciones detalladas y valoraciones críticas de muchas de sus especies. El trabajo se ha realizado a partir de muestras florísticas recolectadas entre los años 1986 y 1989 en las zonas eulitoral y sublitoral superior de la costa de la mitad norte del país, entre Walvis Bay y la desembocadura del río Kunene. Según los datos actuales, la flora bentónica marina de Namibia está representada por 196 táxones (147 Rhodophyceae, 20 Phaeophyceae, 15 Ulvophyceae, 6 Cladophorophyceae y 8 Bryopsidophyceae), 21 de los cuales no habían sido citados hasta el momento de las costas de este país. Se trata de una flora de carácter templado que se caracteriza principalmente por el bajo número de especies, la escasa proporción de feofíceas y el elevado grado de endemismo. En cuanto al número de especies, la flora de Namibia es relativamente pobre, debido a la escasa disponibilidad de substrato colonizable y a la baja diversidad de hábitats. Por otra parte, la baja proporción de feofí-ceas hace que los índices R/P y (R+C)/P adopten valores desproporc...