Using Molecular Power to Reconstruct Hyperdiverse Food Webs

Post provided by JORDAN CASEY

Coral Reefs: The Ocean’s Most Extravagant Buffet

Coral reefs are home to an incredibly diverse array of species ©Jordan Casey

Coral reefs are home to an incredibly diverse array of species ©Jordan Casey

There are an estimated 830,000 species on coral reefs worldwide. At some stage in their lives, nearly all of these species are consumed as prey items. In this super diverse buffet of fishes, corals, crabs, worms, and other critters, the number of possible interactions between predators and prey is nearly inexhaustible.

The extreme diversity of coral reefs has fascinated naturalists for centuries. Pinpointing predator-prey dynamics is essential to fully understand coral reef ecosystem dynamics, and visual analysis of gut contents has been a staple technique of coral reef ecologists. While the joy of spending copious hours looking through a microscope at half-digested marine mush is undeniable, this type of visual inspection has limitations. Even so, visual gut content analysis (along with stable isotope analysis and behavioural observations) has showcased a highly complex dietary network.

To digest this extreme complexity and surmount the hurdle of dietary unknowns, researchers frequently lump fishes into broad trophic categories, such as ‘mobile herbivores’. Broad generalisations are pragmatic and may be help us detect broad ecological trends, but they oversimplify species’ actual dietary preferences. As coral reefs are changing due to anthropogenic disturbances, it’s critical to thoroughly examine how well trophic groupings capture dietary linkages among reef organisms. Continue reading

Testing the Effects of Underwater Noise on Aquatic Animals

Post provided by Karen de Jong

Most people assume that research equipment is expensive and complicated. But, it doesn’t need to be and the noise egg is a perfect example of this. It consists of a watertight container (as used by scuba divers) and the buzzer from a cellphone and does exactly what it says: it produces low frequency noise. This allows researchers to test the effect of noise on underwater life. It is a small, simple and cheap device that anyone can build.

Why Test Effects of Noise?

A painted goby in front of his nest ©K. de Jong

A painted goby in front of his nest ©K. de Jong

Underwater noise is rapidly increasing due to, for example, boat traffic and offshore wind farms. This can lead to stress for animals and difficulties in communication. Just as people have a hard time communicating in a noisy pub, animals may struggle to get their messages across when background noise is high. A nice description of how animals use sound and how noise may affect this can be found at www.dosits.org

While there is some knowledge on the effect of noise on large aquatic animals, we still know very little about how fish and other small aquatic animals are affected. Such knowledge is vital for management of protected areas. It’s also important to know whether wind farms and boat traffic can affect reproduction in populations of underwater resources such as fish and mussels. The answers to these questions are likely to be species specific, so we’ll need data on a large number of species in different habitats. Continue reading