Kenya’s hawkfish and their habitat associations

Will coral reef decline result in the loss of fish species that are closely associated with this habitat?

Subject: Hawkfish ecology
Location: Watamu & Shimoni
Leader: Bob Sluka

Watamu Marine National Park is set on a beautiful, picturesque white coral sand beach. Its lagoon reefs spread across the Park in patches and the fore reef stretches around the outside of the Watamu Marine National Park. The Shimoni, leeward and fore, reefs are located around the different islands and atolls offshore, most within the Kisite Marine National Park and the Mpunguti National Reserve.

The reefs provide shelter and food for a huge variety of species including coral reef fish, many of which have macro and/or microhabitat requirements. The strength of association to these habitats can range from obligate (full reliance on the coral) to facultative (loosely associated to particular corals). The more obligate a species is, the longer it will stay, even if the habitat is degraded. Alongside this, many of these habitats are rapidly changing due to coral bleaching and runoff from the land. Therefore, research has and is being undertaken, to understand what effects these could have on various coral reef fish.

Hawkfish (Cirrhitidae) are one such coral dwelling family. They are relatively small (<30 cm) carnivorous fish, which perch and dart hawk-like for their prey. Hawkfish can be found perching on or in a variety of different corals, including branching species of Acropora and Pocillopora, across Watamu and Shimoni reefs. Much work has been done on hawkfish ecology in the Pacific and Atlantic oceans, but little has been conducted in the Indian Ocean and even less in Kenyan waters. Therefore, this project aimed to provide a baseline of hawkfish species density, diversity and abundance, alongside assessing the two most abundance species’ habitat associations. Hannah Hereward, currently A Rocha UK marine intern, undertook this study across the two different locations within Kenya between January and March 2014.

Arc-eye Hawkfish

An Arc-eye Hawkfish Paracirrhites arcatus perched, waiting to dart off hawk-like for its prey

Hannah discovered five out of the ten hawkfish species which could possibly be found within Kenyan waters (Freckled/Black-side Paracirrhites forsteri, Arc-eye P. arcatus, Pixy/Coral Cirrhitichthys oxycephalus, Stocky Cirrhitus pinnulatus and Twospot Amblycirrhitus bimacula). It is likely that the reefs across Watamu and Shimoni did not fulfil the habitat requirements of the other five (Spotted/Threadfin Cirrhitus aprinus, Dwarf/Falco Cirrhitichthys falco, Redbar Cirrhitops fasciatus, Swallowtail Cyprinocirrhites polyactis and Longnose Oxycirrhites typus). This was expected as many have different habitat associations and depth ranges from 20 m to over 100 m.

SCUBA surveys

Hannah used SCUBA diving equipment to conduct transect surveys underwater

Hannah found that the two most abundant species were Freckled Hawkfish followed by Arc-eye Hawkfish. Further analysis of the data is being conducted to find out if these two species had macrohabitat associations to shallow or deep reef sites and/or microhabitat associations to hard coral cover and/or the proportion of two species of branching hard coral (Pocillopora and Acropora). Hannah suggests that further research into the degradation of branching corals, including Acropora and Pocillopora, will be important in order to determine the longevity of obligate-inclined hawkfish in the future.

 

Kenya's hawkfish

More research is needed to determine how vulnerable they will be to coral degradation

Project in partnership with