Skip to main content

LUP Student Papers

LUND UNIVERSITY LIBRARIES

Occurrence and distribution of the barnacle Stephanolepas muricata Fischer, 1886, on sea turtles in the Golfo Dulce, Pacific, Costa Rica

Zaghdoudi-Allan, Nadege (2013) BIOM21 20121
Degree Projects in Biology
Abstract
Abstract

The barnacle, Stephanolepas muricata, a commensal epibiont of cheloniid sea turtles, occurs frequently on the sea turtles of the Golfo Dulce, Pacific Costa Rica. The aim of this study was to quantify the occurrence of S. muricata on green and hawksbill sea turtles, to describe its major attachment locations and to investigate potential routes for barnacle exposure. In-water sampling of sea turtles (n=31) was used to determine barnacle abundance and distribution. In the Golfo Dulce S. muricata was encountered on green sea turtles (Chelonia mydas) for the first time and was subsequently found to occur on 31% of individuals, whereas it occurred on 100% of hawksbill turtles (Eretmochelys imbricata). Barnacle abundance was highly... (More)
Abstract

The barnacle, Stephanolepas muricata, a commensal epibiont of cheloniid sea turtles, occurs frequently on the sea turtles of the Golfo Dulce, Pacific Costa Rica. The aim of this study was to quantify the occurrence of S. muricata on green and hawksbill sea turtles, to describe its major attachment locations and to investigate potential routes for barnacle exposure. In-water sampling of sea turtles (n=31) was used to determine barnacle abundance and distribution. In the Golfo Dulce S. muricata was encountered on green sea turtles (Chelonia mydas) for the first time and was subsequently found to occur on 31% of individuals, whereas it occurred on 100% of hawksbill turtles (Eretmochelys imbricata). Barnacle abundance was highly variable and hawksbill sea turtles hosted more individual barnacles per turtle (mean = 62 barnacles) than the green sea turtles (mean = 4 barnacles) (p=0.023). S. muricata abundance was significantly greater on hawksbill fore-flippers compared to other attachment locations (p=0.001) but not in the green turtle (p=0.24). Post-nesting green sea turtles from distant rookeries, such as the Galápagos Islands, travel to the continental shelf of Central and South America in search of foraging grounds. Green sea turtles previously lacking S. muricata that come to forage in the Golfo Dulce are potentially being exposed to S. muricata and present avenues for its dispersal throughout the Tropical Eastern Pacific Ocean. The importance of the Golfo as a foraging ground for sea turtles, the high abundance of S. muricata present in the Golfo, and the difficulties in determining dispersal pathways in the barnacle show that additional research is needed to monitor the spread of the barnacles and its effect on the sea turtle populations.

Popular science summary:

Short and attractive title

Sea turtles are long-lived, migratory marine reptiles with a worldwide distribution save for the polar regions. Five of the seven present species are listed on the IUCN Red List of Endangered Species as either ‘Endangered’ or ‘Critically Endangered’ as a result of over harvesting, fish net entanglements and predation. Sea turtles are known to host a wide variety of organisms during their lifetime including different species of algae, worms and barnacles. These organisms, also referred to as ‘epibiota’ can be found attached to the head, flippers and body of sea turtles. One such epibiont is the barnacle Stephanolepas muricata, a small ciriped barnacle that burrows into the tissues of sea turtles, most commonly on the front flippers. The barnacle is exclusively found associated with sea turtles and uses them as an attachment substrate to filter-feed plankton. First described as a parasite by Fischer (1886), the S. muricata-sea turtle relationship is now referred to as commensalism because dietary analysis have not shown the presence of sea turtle tissue and there has been no solid evidence that the barnacle harms its host. Little is known, however, on the biology and fitness effects of S. muricata on sea turtles. The aim of this study is to describe the occurrence and attachment locations of this barnacle on the two species of sea turtle found in the Golfo Dulce, Costa Rica, that is, the hawksbill (Eretmochelys imbricata) and the green sea turtle (Chelonia mydas) and to investigate potential avenues for its dispersal and transmission throughout the Tropical Eastern Pacific Ocean.

Methods
In order to quantify the amount of barnacles found on sea turtles, in-water sampling was conducted whereby a 100 meter net was used to manually catch sea turtles. This method was employed because no nesting occurs in the Golfo Dulce and it is the only means to study sea turtles year-round and the only way to study males.

Implication of the Data

Of 31 sea turtles studied, there was a 100% occurrence of S. muricata on hawksbill turtles (n=15) and the barnacles was encountered on the green sea turtle for the first time in the Golfo Dulce during this study, where 5 out of 16 green sea turtles carried the barnacle. Hawksbill sea turtles hosted on average 62 individual S. muricata barnacles whereas, green sea turtles hosted on average 4 barnacles, demonstrating a statistically significant dichotomy (p=0.023) between the two species. S. muricata barnacles were found in larger numbers on the fore-flippers than on the rear-flippers in hawksbill turtles (p= 0.001), but no significant difference was found between fore- and rear-flippers in green turtles (p=0.24). In addition, no correlation was found between turtle body size and abundance of barnacles for hawksbill turtles (p=0.069) nor for green turtles (p=0.90). Finally, hawksbills that hosted a high number of barnacles were visibly in poor health, examples include, emaciation, sunken eyes and tissue deformations around the areas where large numbers of S. muricata were attached.
This study has shown that S.muricata is prominent in the Golfo, but is associated in larger numbers with hawksbill turtles than green turtles. Field observations of heavy barnacle loads on hawksbills suggested tissue damage and emaciation, but veterinary studies would be necessary to confirm any correlation. The confirmed sightings of two distinct green turtle morphs in Colombia and Costa Rica indicate that turtles are coming from distant nesting grounds, possibly from as far as the Australasia region, to forage in the Tropical Eastern Pacific. Sea turtles are known to be solitary when migrating, but this finding infers that distinct populations and species overlap and share foraging grounds during the inter-reproductive period. Exposure to and transmission of S. muricata would be facilitated by this overlap and is likely a means of dispersing the barnacles to new and distant populations. More recently, post-nesting Galapagos green turtles have been satellite tracked to the Osa Peninsula, where the Golfo Dulce is located (unpublished data) where exposure to S.muricata is highly probable.




Advisors: Michael G. Frick and Per Carlsson
Master´s Degree Project 30 credits in Marine Biology 2012/2013
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
author
Zaghdoudi-Allan, Nadege
supervisor
organization
course
BIOM21 20121
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
3914499
date added to LUP
2013-07-01 12:46:23
date last changed
2013-07-01 12:46:23
@misc{3914499,
  abstract     = {Abstract

The barnacle, Stephanolepas muricata, a commensal epibiont of cheloniid sea turtles, occurs frequently on the sea turtles of the Golfo Dulce, Pacific Costa Rica. The aim of this study was to quantify the occurrence of S. muricata on green and hawksbill sea turtles, to describe its major attachment locations and to investigate potential routes for barnacle exposure. In-water sampling of sea turtles (n=31) was used to determine barnacle abundance and distribution. In the Golfo Dulce S. muricata was encountered on green sea turtles (Chelonia mydas) for the first time and was subsequently found to occur on 31% of individuals, whereas it occurred on 100% of hawksbill turtles (Eretmochelys imbricata). Barnacle abundance was highly variable and hawksbill sea turtles hosted more individual barnacles per turtle (mean = 62 barnacles) than the green sea turtles (mean = 4 barnacles) (p=0.023). S. muricata abundance was significantly greater on hawksbill fore-flippers compared to other attachment locations (p=0.001) but not in the green turtle (p=0.24). Post-nesting green sea turtles from distant rookeries, such as the Galápagos Islands, travel to the continental shelf of Central and South America in search of foraging grounds. Green sea turtles previously lacking S. muricata that come to forage in the Golfo Dulce are potentially being exposed to S. muricata and present avenues for its dispersal throughout the Tropical Eastern Pacific Ocean. The importance of the Golfo as a foraging ground for sea turtles, the high abundance of S. muricata present in the Golfo, and the difficulties in determining dispersal pathways in the barnacle show that additional research is needed to monitor the spread of the barnacles and its effect on the sea turtle populations.

Popular science summary:

Short and attractive title

Sea turtles are long-lived, migratory marine reptiles with a worldwide distribution save for the polar regions. Five of the seven present species are listed on the IUCN Red List of Endangered Species as either ‘Endangered’ or ‘Critically Endangered’ as a result of over harvesting, fish net entanglements and predation. Sea turtles are known to host a wide variety of organisms during their lifetime including different species of algae, worms and barnacles. These organisms, also referred to as ‘epibiota’ can be found attached to the head, flippers and body of sea turtles. One such epibiont is the barnacle Stephanolepas muricata, a small ciriped barnacle that burrows into the tissues of sea turtles, most commonly on the front flippers. The barnacle is exclusively found associated with sea turtles and uses them as an attachment substrate to filter-feed plankton. First described as a parasite by Fischer (1886), the S. muricata-sea turtle relationship is now referred to as commensalism because dietary analysis have not shown the presence of sea turtle tissue and there has been no solid evidence that the barnacle harms its host. Little is known, however, on the biology and fitness effects of S. muricata on sea turtles. The aim of this study is to describe the occurrence and attachment locations of this barnacle on the two species of sea turtle found in the Golfo Dulce, Costa Rica, that is, the hawksbill (Eretmochelys imbricata) and the green sea turtle (Chelonia mydas) and to investigate potential avenues for its dispersal and transmission throughout the Tropical Eastern Pacific Ocean. 

Methods
In order to quantify the amount of barnacles found on sea turtles, in-water sampling was conducted whereby a 100 meter net was used to manually catch sea turtles. This method was employed because no nesting occurs in the Golfo Dulce and it is the only means to study sea turtles year-round and the only way to study males. 

Implication of the Data

Of 31 sea turtles studied, there was a 100% occurrence of S. muricata on hawksbill turtles (n=15) and the barnacles was encountered on the green sea turtle for the first time in the Golfo Dulce during this study, where 5 out of 16 green sea turtles carried the barnacle. Hawksbill sea turtles hosted on average 62 individual S. muricata barnacles whereas, green sea turtles hosted on average 4 barnacles, demonstrating a statistically significant dichotomy (p=0.023) between the two species. S. muricata barnacles were found in larger numbers on the fore-flippers than on the rear-flippers in hawksbill turtles (p= 0.001), but no significant difference was found between fore- and rear-flippers in green turtles (p=0.24). In addition, no correlation was found between turtle body size and abundance of barnacles for hawksbill turtles (p=0.069) nor for green turtles (p=0.90). Finally, hawksbills that hosted a high number of barnacles were visibly in poor health, examples include, emaciation, sunken eyes and tissue deformations around the areas where large numbers of S. muricata were attached. 
This study has shown that S.muricata is prominent in the Golfo, but is associated in larger numbers with hawksbill turtles than green turtles. Field observations of heavy barnacle loads on hawksbills suggested tissue damage and emaciation, but veterinary studies would be necessary to confirm any correlation. The confirmed sightings of two distinct green turtle morphs in Colombia and Costa Rica indicate that turtles are coming from distant nesting grounds, possibly from as far as the Australasia region, to forage in the Tropical Eastern Pacific. Sea turtles are known to be solitary when migrating, but this finding infers that distinct populations and species overlap and share foraging grounds during the inter-reproductive period. Exposure to and transmission of S. muricata would be facilitated by this overlap and is likely a means of dispersing the barnacles to new and distant populations. More recently, post-nesting Galapagos green turtles have been satellite tracked to the Osa Peninsula, where the Golfo Dulce is located (unpublished data) where exposure to S.muricata is highly probable. 




Advisors: Michael G. Frick and Per Carlsson
Master´s Degree Project 30 credits in Marine Biology 2012/2013
Department of Biology, Lund University},
  author       = {Zaghdoudi-Allan, Nadege},
  language     = {eng},
  note         = {Student Paper},
  title        = {Occurrence and distribution of the barnacle Stephanolepas muricata Fischer, 1886, on sea turtles in the Golfo Dulce, Pacific, Costa Rica},
  year         = {2013},
}