Copepod colonisation and parasitism

We are describing and documenting patterns of copepod species to determine how their diversity evolves.

Copepods are one of the most abundant forms of life on Earth. They are dominant in the community of floating microscopic animals in the oceans, and also inhabit the microscopic spaces between sediment grains. Parasitic species of copepod are found on almost every group of animals, from sponges to whales.

Our research is focused on:

• large scale colonisation events, including the colonisation of pools of seawater in coastal caves by primitive copepods and the repeated colonisation of freshwater habitats from marine origins
• how copepod parasitism originated, how parasitic groups have diversified, and how different species use their hosts
• creating and disseminating online resources to improve access to marine species data and to allow identification of parasitic copepods

Copepod colonisations

We are studying the primitive species found in mixed-water caves to explore their early evolution and determine how copepods came to dominate the oceans.

Copepods dominate the oceans, but just how they achieved this from their origins in shallow coastal waters is a complex question.

Some species of copepods found in mixed sea and freshwater caves (anchialine caves) are unusually primitive and provide clues as to how copepods began their invasion of the oceans.

We have collected crustaceans from numerous cave sites in and around the Caribbean and from islands in the South Pacific. These specimens are being documented and described, and their evolutionary history untangled.

So far we have discovered that the colonisation of these caves probably occurred at least 100 million years ago during the age of the dinosaurs.

In freshwater systems, the Cyclopidae family of copepods is dominant, with more than 900 species. We are also studying how this family has expanded and adapted to new ecological niches.

Copepods as parasites

We are investigating how parasitic copepods have evolved and continue to adapt to new hosts.

Many copepod species have independently adapted to a parasitic way of life using a wide range of animals as hosts. How patterns of new host use develop in copepods is largely unknown.

We are researching:

• host use patterns, by measuring and comparing the range of hosts used by different parasite groups
• examples of major host-switching events, where different groups are suddenly colonised
• the invasion of alien parasites through the Suez Canal, switching from Red Sea to Mediterranean fish species
• the diversity of parasites in Northern European marine waters, including the description of many new species and genera of parasites from polychaete and molluscan hosts in UK waters

Sea lice in aquaculture

We are studying the life cycle of sea lice, a prevalent and devastating threat to commercial aquaculture worldwide.

Whenever new fish are taken into marine aquaculture, sea lice are sure to follow. These parasitic copepods pose a major health hazard for finfish aquaculture globally, causing substantial economic loss when they strike fish farms.

We are researching sea lice in order to determine how to minimise their impact on commercial aquaculture.

We are focussing on:

• the life cycle of sea lice in collaboration with groups in Japan and South Korea
• revising the classification of sea lice using DNA sequence data
• building an online interactive identification key for sea louse species

We have already identified that the life cycle of the salmon louse genus (Lepeophtheirus) contains two fewer stages than previously thought, which could help manage infestations.

External collaborator: T. Chad Walter (Smithsonian Institution)