Investigating ecosystems: Practice Questions

When systematically investigating the distribution of different species along a gradient, such as from the high tide mark to the low tide mark on a rocky shore, which sampling method is most appropriate?

When investigating the profile of a shore or slope in a marine ecosystem, which method is typically used to measure changes in elevation?

A student uses five \(1.0\text{ m}^2\) quadrats to estimate the population of snails in a rocky shore area measuring \(500\text{ m}^2\). The counts in the quadrats are 8, 12, 7, 10, and 13. What is the estimated total population of snails in this area?

A marine scientist wants to systematically investigate how the distribution and abundance of specific organisms change along the length of a sandy beach, from the high tide mark towards the water's edge. Which sampling technique is most appropriate for this investigation?

A marine biologist wants to investigate whether the population of a specific burrowing worm is evenly distributed across a large, uniform mudflat. Which sampling strategy would be most scientifically robust for this investigation?

When investigating population sizes, why is random sampling used rather than choosing specific spots to place a quadrat?

A student samples a muddy shore using five \(0.25\text{ m}^2\) quadrats and identifies 6 different species of invertebrates. State the species richness of this sample and suggest one reason why this value might be an underestimate of the true richness of the shore.

Describe how a student could modify the standard method for measuring moisture content to specifically investigate how sediment desiccation varies with vertical depth below the sand surface.

A student investigates the species richness of two different rock pools on a rocky shore using a quadrat measuring \(0.25\text{ m}^2\). The data collected is shown below:

A marine biologist is conducting an ecological survey to investigate zonation and diversity on a muddy shore.
(a)<\/b> The biologist chooses to use an interrupted belt transect<\/b> rather than a continuous belt transect<\/b>. Explain the difference between these two methods and suggest one reason why the interrupted method might be preferred for a wide shore.
(b)<\/b> To avoid bias when collecting sediment samples within the mid-shore zone, the biologist uses a random sampling<\/b> strategy. Describe how the biologist would use a random number generator and tape measures to determine the exact sampling locations.
(c)<\/b> Define the term species richness<\/b>. If the biologist is comparing the richness of two different shores, explain why they must ensure the total area sampled<\/b> is identical on both shores to obtain a valid result.<\/p>