259
0-8493-1123-3/03/$0.00+$1.50
© 2003 by CRC Press LLC
10 Roles of Sea Turtles
in Marine Ecosystems:
Reconstructing the Past
Karen A. Bjorndal and Jeremy B.C. Jackson
CONTENTS
10.1 Introduction .................................................................................................259
10.2 Ecological Roles of Sea Turtles .................................................................261
10.3 Case Study: Caribbean Green Turtle ..........................................................262
10.4 Case Study: Caribbean Hawksbill ..............................................................265
10.5 Conclusions .................................................................................................269
Acknowledgments ................................................................................................269
References ............................................................................................................270
10.1 INTRODUCTION
Populations of sea turtles have been drastically reduced since interactions between
humans and sea turtles began. Although Caribbean sea turtle populations generally
have been considered to be pristine when Columbus arrived in 1492, archeological
research is now revealing that some sea turtle nesting aggregations in the Caribbean
were extirpated or significantly reduced by Amerindians (Carlson, 1999; O’Day,
2001). Therefore, the roles that sea turtles played in the functioning of ecosystems
in the Caribbean may have been substantially affected before European contact.
Initially a result of directed harvest, population declines have more recently been
driven by factors in addition to direct harvest, such as incidental capture in commercial fisheries, habitat degradation, introduction of feral predators on nesting
beaches, and marine pollution (Eckert, 1995; Lutcavage et al., 1997; Witherington,
in press). These population declines have produced a corresponding decline in the
extent to which sea turtles fulfill their roles in maintaining the structure and function
of marine ecosystems.
Because the massive proportions of the declines occurred so long ago, sea
turtles are now viewed by many as charming anachronisms or quaint archaic relics.
Their past roles as major marine consumers in many marine ecosystems from
1123 book.book Page 259 Monday, November 11, 2002 11:11 AM
0-8493-1123-3/03/$0.00+$1.50
© 2003 by CRC Press LLC
10 Roles of Sea Turtles
in Marine Ecosystems:
Reconstructing the Past
Karen A. Bjorndal and Jeremy B.C. Jackson
CONTENTS
10.1 Introduction .................................................................................................259
10.2 Ecological Roles of Sea Turtles .................................................................261
10.3 Case Study: Caribbean Green Turtle ..........................................................262
10.4 Case Study: Caribbean Hawksbill ..............................................................265
10.5 Conclusions .................................................................................................269
Acknowledgments ................................................................................................269
References ............................................................................................................270
10.1 INTRODUCTION
Populations of sea turtles have been drastically reduced since interactions between
humans and sea turtles began. Although Caribbean sea turtle populations generally
have been considered to be pristine when Columbus arrived in 1492, archeological
research is now revealing that some sea turtle nesting aggregations in the Caribbean
were extirpated or significantly reduced by Amerindians (Carlson, 1999; O’Day,
2001). Therefore, the roles that sea turtles played in the functioning of ecosystems
in the Caribbean may have been substantially affected before European contact.
Initially a result of directed harvest, population declines have more recently been
driven by factors in addition to direct harvest, such as incidental capture in commercial fisheries, habitat degradation, introduction of feral predators on nesting
beaches, and marine pollution (Eckert, 1995; Lutcavage et al., 1997; Witherington,
in press). These population declines have produced a corresponding decline in the
extent to which sea turtles fulfill their roles in maintaining the structure and function
of marine ecosystems.
Because the massive proportions of the declines occurred so long ago, sea
turtles are now viewed by many as charming anachronisms or quaint archaic relics.
Their past roles as major marine consumers in many marine ecosystems from
1123 book.book Page 259 Monday, November 11, 2002 11:11 AM