A model to estimate the ecological status and identify restoration targets of transitional and coastal waters was developed. Marine benthic macrophytic species (seaweeds, seagrasses) were used to indicate shifts in the aquatic ecosystem from the pristine state with late-successional species (Ecological State Group I) to the degraded state with opportunistic (ESG II) species. The first group comprises species with a thick or calcareous thallus, low growth rates and long life cycles (perennials), whereas the second group includes sheet-like and filamentous species with high growth rates and short life cycles (annuals). Seagrasses were included in the first group, whereas Cyanophyceae and species with a coarsely branched thallus were included in the second group. The evaluation of ecological status into five categories from high to bad includes a cross comparison in a matrix of the ESGs and a numerical scoring system (Ecological Evaluation Index). The model could allow comparisons, ranking and setting of priorities at regional and national levels fulfilling the requirements of the EU Water Frame Directive. A successful application of the model was realized in selected lagoons of the Macedonian and Thrace region (North Greece) and in the Saronic Gulf coastal ecosystems (Central Greece).

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Ecological evaluation of transitional and coastal waters: A marine benthic macrophytes-based model.

One of the most fundamental and precarious stages in the life history of a marine benthic alga is the colonization of a new substratum. For the majority of algae this is achieved by the formation and detachment of different types of highly specialized reproductive propagules which are then dispersed via the pelagic zone. This paper reviews the process of “settlement”, “attachment” and “establishment” of these propagules. Particular attention is given to the influence of substratum surface properties, both physical and chemical, on these processes, along with aspects of the derivation, chemical composition, mechanisms of release and mode of action of the various adhesives secreted by the attaching spores and germlings.

https://www.tandfonline.com/doi/pdf/10.1080/00071619200650281

The settlement, attachment and establishment of marine algal spores

Publisher Summary The aim of this chapter is to provide a synthesis of recent studies on the ecology of seaweeds at the population and community levels of organization. Ecophysiological studies that relate directly to population and community organizations have also been included within the scope of the review. In general, however, little attention is given to the ecology of seaweeds at the organismic level. A study of recent literature reveals that at least 100 studies relating directly to the population and community ecology of seaweeds have been carried out since 1980. At the community level, there is a continuing flood of publications describing bio-interactions. The new data allow a re-assessment of general models of community organization put forward in the mid and late 1970s. The geographic organization of species assemblages falls within the scope of a review of community organization and there is no qualitative difference between geographical and ecological distributions. The new information can be used to re-examine (and in many cases refute) the conclusions of over 50 years of study on the distribution physiology of seaweeds.

Population and community ecology of seaweeds

Potential of macroalgae for biodiesel production: Screening and evaluation studies

A decrease in salinity and temperature over the past 3000 years has presented the marine algae of the Baltic Sea with very considerable problems in adaptation The effects of salinity upon a number of Baltic algae have been measured The results showed cell mortality to be severe in 0, 68 and 102‰, and minimal in 6 and 11‰: there was most variation in tolerance to 34 and 51‰ The salt tolerances of Baltic marine algae have proved more hyposaline than those of British intertidal algae Water uptake and loss in tissues of Chorda filum and Fucus vesiculosus from Baltic and British populations have been measured in response to salinity changes The results revealed significant population differences in both live and killed tissues Receptacle development and oogonial maturation have been observed in Baltic and British F vesiculosus, and found to differ in seasonality Some observations were associated with local sea temperatures but differences in the timing of receptacle initiation and in oogonial size were

Recent evolutionary changes in the algae of the Baltic Sea

There is no important difference in principle between the cultivation of plant species singly and together in mixed culture. Marine algae have been grown successfully in unialgal culture for many years and one might therefore expect to find in the literature a reasonable number of studies on the behaviour of these plants in controlled competition. Yet the published accounts of mixed culture are very few and invariably lacking control or quantification, or both. It is hard to resist unfavourable comparison with the impressive body of research on competition between higher plants. Interspecific competition is widely held to be an important factor in the often-observed sharp delimitation of marine algal communities. As such it has been freely discussed from theoretical considerations and from field observations by workers such as Chapman (1973), Dayton (1971, 1973), and den Hartog (1968). However, the experimental evidence which might illuminate such discussion is virtually absent. In some respects this unique situation is understandable. Species mixtures are always more difficult to handle than monocultures and, in the particular case of marine algae, there are additional problems of polymorphisms and life histories of almost baroque complexity. Nevertheless the difficulties should not be overstressed for they are not insuperable. The aim of the following experiments was therefore to examine the performances of selected marine algae in monoculture and in competition with one another. By this means it was hoped that the incidence and scale of interspecific competition could be determined to serve as a simple model of a marine community in nature.

The Competitive Properties of Marine Algae in Culture

SUMMARY The intertidal vegetation of Hilbre Island, Merseyside, is compared with that of seven unpolluted localities on the Isle of Man and with that of New Brighton, Merseyside, which is grossly polluted. The Hilbre and New Brighton samples may be assigned either to the littoral fringe or to the eulittoral zone but not to the sublittoral fringe as defined by Lewis (1961). The Hilbre samples are floristically intermediate between those from New Brighton and the Isle of Man. This intermediate character is also apparent in species diversity, life-form composition, biomass and dominance. These features, together with historical evidence, illustrate the process of degradationl which the Hilbre vegetation has undergone throughout this century, and suggest possible future trends.

George Russell

Papers

The Competitive Properties of Marine Algae in Culture

Vegetation on rocky shores at some north irish sea sites

The Effect of Copper on Competition Between Marine Algae