tourism and manta rays part 5: disturbance of cleaning stations from tourism activities by dr....
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Tourism and Manta rays
Part 5: Disturbance of cleaning stations from tourism activities
By Dr. Anne-Marie Kitchen WheelerProject Founder
Manta Ecology Project
In North Male the majority of cleaning stations are nearby resorts.
The most important site was Lankan, located next to Paradise resort but recently, sightings of mantas have been very infrequent.
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ExamplesThere is the precedent that construction of the lagoon entrance to Paradise island in 1995 required dynamiting inner lagoon reef and that mantas avoided Lankan until 2003. i.e. resort development upset manta activity locally. The mantas have disappeared again, so could some change at the resort have caused the change or is it merely due to too many divers at Lankan?
Specific sites still have cleaners but no mantas e.g. Ukulhas, Dhonkalo and Prisca have been very active manta cleaning stations in the past but mantas are now rarely seen there despite few divers now visiting these sites.
Observations of the cleaning station at Lankan suggest that the cleaning fish are there when the mantas are present and absent (or present in much smaller numbers) when the mantas are not visiting. This observation was unexpected. 4
Divers: positive or negative effect?It has been suggested that the presence of divers attracts manta rays at some cleaning stations.
They seek out exhaled bubbles and swim through them as if enjoying a jacuzzi.
There is no evidence of a detrimental effect of bubbles at either cleaning or feeding locations.
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Divers standing or kneeling on the reef will of course have a detrimental effect, damaging the reef and spoiling the habitat of the cleaner fish!
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Data
Madivaru is a very regularly dived manta cleaning station in South Ari Atoll. Many divers and guides have told me that it is “not as good as it used to be”. As a simple test I investigated my own reports of the numbers of mantas seen during my own visits over the past 11 years and there appears to be no significant decrease in the number of mantas I have encountered.
This is NOT the case at Lankan where sightings dropped to zero throughout the majority of surveys during the SW monsoons in 2012 and 2013.
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Coral rubble tipped on reef slope obliterating growing coral.
Pilings built onto coral crown on reef edge severely damaging fringing reef.
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So what is going on?
We are getting mixed messages!
Mantas are missing from regular sites but continue to visit other equally heavily visited sites.There are sites where the cleaner fish are abundant yet the mantas are not seen.
These are complicated, multi-faceted issues with so many potential influences we will probably never get an objective answer.
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There are so many possible influences that it is impossible to measure them all but there are some common-sense actions that should be taken
Protect the reefs:
Measure what we have:
• Educate divers about how to dive to protect the reef
• Environmental impact surveys pre, during and post development. Developers should act responsibly
• Get more divers involved in our ID project so we know how many mantas we have, where they go etc.
• The reefs need to be surveyed for condition of coral, fish numbers etc.
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References• Anderson RC, Adam MS, Kitchen-Wheeler A, Stevens G (2010) Extent and economic value of
manta ray watching in the Maldives. Tourism in Marine Environments 7: 15-27 • Bshary R, Côté IM (2008) New perspectives on marine cleaning mutualism. In: Magnhagen C,
Braithwaite VA, Forsgren E, Kappor BG (eds) Fish behaviour. Science Publishers, Enfield (NH), pp 563–592.
• Feder HM (1966) Cleaning symbiosis in the marine environment. In: Henery M (ed) Symbiosis. Academic Press, New York, pp 327-390
• Gooding RM (1964) Observations of fish from a floating observation raft at sea. Proc Hawaiian Acad Sci 39: 27
• Grutter AS (1995) Relationship between cleaning rates and ectoparasite loads in coral reef fishes. Marine Ecology Progress Series 118: 51-58
• Kitchen-Wheeler A-M, Edwards AJ (In review) How often do manta rays visit cleaning stations in the Maldives? Environmental Biology of Fishes
• Kitchen-Wheeler A-M (2013) The behaviour and ecology of Alfred mantas (Manta alfredi) in the Maldives. PhD Thesis, Newcastle University, UK
• Losey GS (1972) The ecological importance of cleaning symbiosis. Copeia 1972: 820-833 • Youngbluth MJ (1968) Aspects of the ecology and ethology of the cleaning fish Labroides
phthirophagus Randall. Zeitschrift für Tierpsychologie 25: 915-932
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