Exercises: Local ecosystems

Look at the ecosystem classification diagram. State in which box (1, 2, or 3) you would place each of these ecosystems: a holm oak wood, a coral reef, a mountain lagoon, a dehesa (wooded pastureland), a posidonia meadow, and a river.

Name two terrestrial ecosystems characteristic of mainland Mexico and one specific to the Baja California Peninsula or the Yucatán Peninsula, mentioning a typical species from each.

Describe the ecosystem closest to your local area: state whether it is terrestrial or aquatic, name three living things that inhabit it, and mention an important abiotic factor in it.

Point out two differences between a freshwater ecosystem and a marine ecosystem and explain why most fish cannot move from one environment to the other.

A dehesa is a holm oak or cork oak wood cleared by humans to be used as pasture and farmland. Explain why it is considered a human-modified ecosystem while also being an example of sustainable land use with high biodiversity.

On the island of Cozumel, there are species, such as the pygmy raccoon, that live nowhere else in the world (endemic species). Explain the role island isolation plays in the occurrence of endemic species.

During the expansion of a marina over a Posidonia oceanica meadow, the construction work drastically increases water turbidity and deposits fine sediments onto the seabed. The project developer claims: 'The meadow will not suffer any damage because the breakwater is being built 50 meters away and we are not directly uprooting any plants.' Refute this claim by explaining the physiological effects that turbidity and sedimentation cause on these marine plants. Furthermore, predict two cascading ecological consequences on the coastal ecosystem and local fisheries.

An amateur environmental group proposes restocking a river estuary by introducing brown trout specimens caught in the upper course of that same river, arguing that 'since it is the same river basin, the species will acclimate without any issues.' Refute the ecological and physiological viability of this proposal by analysing how three abiotic factors vary (current velocity, temperature and dissolved oxygen concentration, and salinity) between both sections. Justify why the adaptations of these resident trout, moved without prior acclimation, would make their survival in the river mouth very unlikely.

You want to compare the biodiversity of a plantation pine forest with that of a nearby holm oak wood. Design a simple study: state what you would observe or count, how you would make the measurements comparable, and what result you would expect to get.