Book contents
2 - Methodological Considerations
Published online by Cambridge University Press: 18 August 2009
Summary
COLLECTION OF SAMPLES
This chapter emphasizes only those techniques that are pertinent to unconsolidated sediments, and essentially applicable to both foraminifera and thecamoebians. The collection and processing of hard-rock samples is rarely necessary for contemporary environmental impact evaluations. For further information on hard-rock processing, readers are referred to papers by Wightman et al. (1994), Thomas and Murney (1981), or any of the many papers dealing with microfossils in shale or sandstone.
Methods of sampling testate rhizopods are greatly facilitated by the small size and abundance of these shelled protozoans. However, because of the need to ensure that the upper several centimeters of sediment remain undisturbed during the collection process, a variety of sampling methods have been developed over the years.
Surface Samples
Most conventional spatial surveys rely on one of several types of grab samplers. Selecting a particular model is influenced by project goals and logistical and sample quality considerations. For nearshore environments that are being accessed using small craft, the 15 × 15 cm Ekman dredge sampler provides a good-quality small-surface (10 × 10 cm) sample. The closing mechanism of this device is triggered by a weight that is released at the surface after the sampler has “landed” on the seafloor. The weight slides down the hauling rope and strikes a plate that releases the spring-loaded sampler jaws (Fig. 2.1).
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- Publisher: Cambridge University PressPrint publication year: 2001