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The main differences between the linear and areal types of littoral habitats are in their shape, structure and the hydro- and litho-dynamic, salinity and ecological gradients between terrestrial and aquatic environments. Understanding the nature of linear littoral habitats is important for interpreting the 'coastal squeeze' effect. The aim of this study is to analyse and compare the integrity of the key linear littoral habitats adjacent to two European lagoons-Lesina Lagoon on the Adriatic Sea and the Curonian Lagoon on the Baltic Sea. Among the four linear habitats selected for this study, we found that the glasswort ( Salicornia spp.) swards showed the highest level of integrity, while the reed beds showed the lowest level of integrity. The linear littoral habitats rely on the dynamic equilibrium conditions. Hence, the strip of glasswort swards and the freshwater dune slack ponds of Bosco Isola di Lesina both depend upon climatic conditions that determine the shape of the salinity gradient. This gradient runs perpendicular to the coast and is based on a transition from fresh groundwater to saline water. The chain of shifting coastal dunes and the reed beds of the Curonian Spit depend upon the long-shore hydro- and litho-dynamic flow conditions. [ABSTRACT FROM AUTHOR]

Toxic cyanobacteria can have harmful or fatal impacts on aquatic organisms. In the archipelagos of the northern Baltic Sea, the open sea blooms often drift into littoral areas, where they decompose and release toxins and other chemical compounds in the water. However, the effects of cyanobacteria on the littoral organisms have not previously been investigated. We studied the effects of three cyanobacteria species (toxic Nodularia spumigena, non-toxic N. sphaerocarpa and non-toxic Aphanizomenon flos-aquae) and purified dissolved nodularin (produced by N. spumigena) on a common littoral amphipod Gammarus zaddachi. Nodularin was transferred to eggs, juveniles and adults of G. zaddachi, but no significant negative effects of dissolved nodularin were detected on adults, eggs or juveniles. However, survival of adults decreased by the exposure to toxic N. spumigena cells. The egg hatching rate and juvenile survival were not affected when exposed to the three cyanobacteria species. In contrast, a weak decrease in the egg production and an increased abortion of embryos from the brood pouch of females was observed, the later indicating a failure in parental care. Further, a decrease in grazing rate on the filamentous green alga Enteromorpha intestinalis was observed. The results suggest that toxic cyanobacteria blooms are not extremely fatal, but may have, in high concentrations, negative effects on the adult survival, fecundity, and feeding behaviour of gammarids inhabiting the littoral zone. [ABSTRACT FROM AUTHOR]

Environmental and/or genetic among-site variation in plant quality may influence growth and fecundity of specialized herbivores inhabiting a particular site. Such variation is important as it generates spatial variation in selection for traits related to plant-herbivore interaction. Littoral macroalgae are known to respond plastically to environmental variation by modifying their chemistry or morphology. We studied geographic variation in phlorotannin, nitrogen, protein, and sugar (fucose, mannitol, and melibiose) concentrations of the brown algaFucus vesiculosusat 12 sites separated by 0.5 to 40 km in the naturally fragmented Archipelago Sea in the northern Baltic Sea. By this regional variation in algal chemistry we attempted to explain among-population variation in size and fecundity of the crustacean herbivoreIdotea baltica. We observed high spatial variation in all the measured chemical characteristics ofF. vesiculosus, as well as in female size and the number of eggs produced by the herbivores. Spatial variation in nitrogen or protein contents of the alga did not explain the variation of herbivore traits. However, egg size positively covaried with spatial variation in the concentration of mannitol, the major storage carbohydrate of the alga. Such a positive relationship may arise ifI. balticacan utilize the nutritive value of a mannitol-rich diet thereby being better able to provision the developing eggs with energy-rich metabolites. Unexpectedly, the concentration of phlorotannins, secondary metabolites having a putative role in defense against herbivory, positively covaried with the size of the herbivore. Among-population variation in host plant chemistry and covariation of that with herbivore growth and reproduction imply that herbivores respond to the local quality of their host plants, and that geographical structuring of populations has to be taken into account in studies of plant-herbivore interactions. [ABSTRACT FROM AUTHOR]