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The ichnogenus Skolithos Haldeman 1840 is a simple tubular trace fossil that was initially described as a "fucoid" or seaweed impression, i.e., a fossilized marine plant. Today the tracemaker is commonly considered to have been a vermiform marine invertebrate, although this interpretation is not acceptable to all. It is the name giver to the archetypal, Seilacherian Skolithos ichnofacies, which is a widely acknowledged indicator of relatively high energy, shallow water, nearshore to marginal marine environments. Here we record and describe analogous cylindrical structures, unquestionably reflecting plant tracemakers. These have been recognized in Quaternary consolidated "coffee" sandrock and Recent coastal dune, marsh or swamp, and salt meadow settings from northern New Zealand and Sapelo Island, USA. We conclude that Skolithos is not an unequivocal indicator of shallow marine settings. Our observations confirm the opinions of a number of previous workers who have expressed the need for caution when using this ichnotaxon as a shallow-water, higher energy palaeoenvironmental indicator, especially when supporting evidence is otherwise lacking. In particular we note that in high intertidal and non-aquatic settings, Skolithos may be a plant trace fossil rather than serve as evidence for invertebrate activities. At the present time there is pressing need for a thorough systematic revision of the Skolithos ichnotaxon. [ABSTRACT FROM AUTHOR]

Data from an initial impact study were used to develop a labour-efficient index for biological monitoring of dredge spoil disposal. Each of 12 indicator species was assigned a score, based primarily on the ratio of its abundance in control vs impacted samples. The `Index' value was the average score of those indicator species present in the sample. The Index was tested during a second survey. Sample processingfor Index calculation took only 25% of the time required to process all macrofauna. The Index value provided a sensible, semi-quantitative indication of impact on benthic macrofauna. Index values of <2, 2-6and>6 were indicative of `severe', `patchy' and `no' impact respectively. Mean Index value correlated with mean macrofaunal richness (r =0.93, P < 0.05) and abundance (r = 0.92, P < 0.05). While the Index is site- and impact-specific, the process of developing efficient monitoring tools from an initial impact study should be widely applicable. [ABSTRACT FROM AUTHOR]