One reason for this is that the relationships were not similar in all the areas; another reason is the possible influence of seasonality. The relationships at Kõiguste were stronger (e.g. Figure 4), where the phytobenthos

biomass was the highest. The relationships at Sõmeri were mostly similar to but weaker than those at Kõiguste, whereas Orajõe often displayed mixed or unclear relationships with hydrodynamics. For instance, the relationships between frame coverage and wave height was positive at Kõiguste, weak (or mixed) at Sõmeri and negative at Orajõe. According to Viikmäe & Soomere (2014), a straight coastline seems to have less chance of receiving material. However, it appears that the straight coastline of Orajõe mostly receives its wrack in regular hydrodynamic conditions and occasionally due to currents, Ruxolitinib mw while high sea level and wave (swash) events may even carry some of the wrack material back GSK J4 to sea. We should bear in mind that the Orajõe region has the scarcest bottom vegetation

and also showed somewhat larger discrepancies between the two tested hydrobiological sampling methods (Table 4). The stronger relationships with waves and sea level variations and the weaker ones with currents justify the use of wrack samples for assessing species occurrences in the sea. The formation of beach wrack requires a certain amount of wave activity to rip the organisms from their substrate

and then to cast them up on to the shore. On the other hand, weak correlations Benzatropine with currents show primarily that the alongshore currents in the practically tideless Estonian coastal sea are meteorologically driven and not strong enough (Figure 3) to compete with waves in ripping off the benthos. Also, the current in the Estonian coastal sea typically reverses on average once every 0.9 days, and the current direction is sustained for more than five days less than five times per year (Figure 3b; Suursaar et al. 2012). The absence of long seasonal or tidal currents and the infrequent occurrence of any other kind of persistent circulation ensure that the material on the beach originates in the adjacent sea areas. On the other hand, in such semienclosed boreal seas, high sea level and wave events occur on an almost regular basis at least every 10–30 days, less often in summer and more frequently in autumn, providing fresh material for the beach wrack (see also Filipkowska et al. 2009). We can also conclude that it is advisable to skip long-lasting calm weather conditions and go for beach wrack sampling after a storm. In general, the stronger the storm event, the richer the wrack strip (Figure 4). As in tidal seas, the wrack statistically tends to be more abundant during spring tides than neap tides (e.g. Ochieng & Erftemeijer 1999). In general, the effectiveness of the various sampling methods (e.g.