Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 275 (1641), 1351-8

Extinction Rate, Historical Population Structure and Ecological Role of the Caribbean Monk Seal

Affiliations

Extinction Rate, Historical Population Structure and Ecological Role of the Caribbean Monk Seal

Loren McClenachan et al. Proc Biol Sci.

Abstract

The productivity and biomass of pristine coral reef ecosystems is poorly understood, particularly in the Caribbean where communities have been impacted by overfishing and multiple other stressors over centuries. Using historical data on the spatial distribution and abundance of the extinct Caribbean monk seal (Monachus tropicalis), this study reconstructs the population size, structure and ecological role of this once common predator within coral reef communities, and provides evidence that historical reefs supported biomasses of fishes and invertebrates up to six times greater than those found on typical modern Caribbean reefs. An estimated 233,000-338,000 monk seals were distributed among 13 colonies across the Caribbean. The biomass of reef fishes and invertebrates required to support historical seal populations was 732-1018 gm(-2) of reefs, which exceeds that found on any Caribbean reef today and is comparable with those measured in remote Pacific reefs. Quantitative estimates of historically dense monk seal colonies and their consumption rates on pristine reefs provide concrete data on the magnitude of decline in animal biomass on Caribbean coral reefs. Realistic reconstruction of these past ecosystems is critical to understanding the profound and long-lasting effect of human hunting on the functioning of coral reef ecosystems.

Figures

Figure 1
Figure 1
Monk seal discovery curve. Interest in the monk seal in the mid-nineteenth century led to increasing numbers of observations, but few new discoveries (this does not include archaeological or data taken from maps). Squares, independent observations; circles, new populations observed.
Figure 2
Figure 2
Total extent of the Caribbean monk seal range over time. Early observations (triangles, before the eighteenth century) were recorded as far east as the Lesser Antilles and Guyana. Observations from the eighteenth and nineteenth centuries (squares) were recorded in most of the Caribbean basin, but, by 1900, observations (small circles) were restricted to the western Caribbean and Gulf of Mexico. The most persistent population (large circle, last colony) was found on the Serrana Bank. Observations in the western Gulf of Mexico are unconfirmed.
Figure 3
Figure 3
Locations of breeding colonies. Observations were coded and ranked into eight data types. Data types 1–4 were used to infer the presence of a breeding colony, assuming a minimum distance of 300 km between groups. Large circles represent the area encompassed by a 300 km home range and the date of last observation is listed for each colony. Data type: 1, observed breeding colony (filled circles); 2, groups of seals on land in the winter (filled down triangles); 3, groups of seals on land (filled squares); 4, large abundance (filled up triangles); 5, presence observed (open circles); 6, seals in water/irregular presence noted (open down triangles); 7, archaeological data (open squares); 8, place name or data from map (open up triangles).
Figure 4
Figure 4
Probability of extinction. The extinction of Caribbean monk seal colonies occurred in two distinct phases. The probability of extinction in each phase is a function of the distance from the centre of the range, with colonies on the periphery having a higher probability of extinction in both the phases. Phase 1, eighteenth century (circles); phase 2, twentieth century (squares).
Figure 5
Figure 5
Historical reef fish biomass implied by monk seal population estimates. The biomass of reef fishes required to sustain the estimated population of historical monk seals (ranging from 233 000 to 338 000 seals in the entire Caribbean) is four to six times greater than the average Caribbean reef, which exceeds that found on the most pristine Caribbean coral reefs today (data from Newman et al. 2006) and is in the same range of the most pristine reefs worldwide (data from NOAA Fisheries, Pacific Islands Fisheries Science Center, Coral Reef Ecosystem).

Similar articles

See all similar articles

Cited by 15 PubMed Central articles

See all "Cited by" articles

Publication types

LinkOut - more resources

Feedback