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Patterns of coral disease across the Hawaiian archipelago: relating disease to environment.

Aeby GS, Williams GJ, Franklin EC, Kenyon J, Cox EF, Coles S, Work TM - PLoS ONE (2011)

Bottom Line: These results highlight the importance of understanding disease ecology when interpreting patterns of disease occurrence.In contrast, the high occurrence of PorGAs within the MHI suggests that PorGAs are related, directly or indirectly, to some environmental co-factor associated with increased human population sizes.The association with human population density differed among disease states with PorGAs showing a positive and PorTrm showing a negative association, but no significant explanatory power was offered for PorTLS.

View Article: PubMed Central - PubMed

Affiliation: Hawai'i Institute of Marine Biology, University of Hawaii, Kaneohe, Hawai'i, United States of America. greta@hawaii.edu

ABSTRACT
In Hawaii, coral reefs occur across a gradient of biological (host abundance), climatic (sea surface temperature anomalies) and anthropogenic conditions from the human-impacted reefs of the main Hawaiian Islands (MHI) to the pristine reefs of the northwestern Hawaiian Islands (NWHI). Coral disease surveys were conducted at 142 sites from across the Archipelago and disease patterns examined. Twelve diseases were recorded from three coral genera (Porites, Montipora, Acropora) with Porites having the highest prevalence. Porites growth anomalies (PorGAs) were significantly more prevalent within and indicative of reefs in the MHI and Porites trematodiasis (PorTrm) was significantly more prevalent within and indicative of reefs in the NWHI. Porites tissue loss syndrome (PorTLS) was also important in driving regional differences but that relationship was less clear. These results highlight the importance of understanding disease ecology when interpreting patterns of disease occurrence. PorTrm is caused by a parasitic flatworm that utilizes multiple hosts during its life cycle (fish, mollusk and coral). All three hosts must be present for the disease to occur and higher host abundance leads to higher disease prevalence. Thus, a high prevalence of PorTrm on Hawaiian reefs would be an indicator of a healthy coral reef ecosystem. In contrast, the high occurrence of PorGAs within the MHI suggests that PorGAs are related, directly or indirectly, to some environmental co-factor associated with increased human population sizes. Focusing on the three indicator diseases (PorGAs, PorTrm, PorTLS) we used statistical modeling to examine the underlying associations between disease prevalence and 14 different predictor variables (biotic and abiotic). All three diseases showed positive associations with host abundance and negative associations with thermal stress. The association with human population density differed among disease states with PorGAs showing a positive and PorTrm showing a negative association, but no significant explanatory power was offered for PorTLS.

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Constrained CAP ordination of coral disease assemblages for 136 sites at 14 islands across the Hawaiian archipelago.Group centroids are displayed for each island (MHI – black, NWHI – red). Ordination is based on a zero-adjusted Bray-Curtis coefficient. Bi-plot indicates the disease variables (vectors) exerting the strongest influence on the patterns in multivariate space (in grey). The length and direction of each vector indicates the strength and sign, respectively, of the relationship between that disease variable and the CAP axes. Note that Acropora diseases are not included in the analysis. FFS, French Frigate Shoals; P&H, Pearl and Hermes. PorTrem, Porites trematodiasis; PorTL, Porites tissue loss; PorGA, Porites growth anomalies.
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pone-0020370-g004: Constrained CAP ordination of coral disease assemblages for 136 sites at 14 islands across the Hawaiian archipelago.Group centroids are displayed for each island (MHI – black, NWHI – red). Ordination is based on a zero-adjusted Bray-Curtis coefficient. Bi-plot indicates the disease variables (vectors) exerting the strongest influence on the patterns in multivariate space (in grey). The length and direction of each vector indicates the strength and sign, respectively, of the relationship between that disease variable and the CAP axes. Note that Acropora diseases are not included in the analysis. FFS, French Frigate Shoals; P&H, Pearl and Hermes. PorTrem, Porites trematodiasis; PorTL, Porites tissue loss; PorGA, Porites growth anomalies.

Mentions: Disease assemblages differed significantly between regions (Pseudo-F = 9.905, P = 0.0001), with three diseases, Porites trematodiasis (PorTrem), Porites growth anomalies (PorGA), and Porites tissue loss syndrome (PorTL) contributing most strongly to driving this separation (Fig. 4). Increased levels of PorTrem were associated with the Northwestern Hawaiian Islands (French Frigate Shoals, Kure, Maro, Laysan and Lisianski) and average prevalence of PorTrem was significantly higher in the NWHI (10.7±2.2%) compared to the MHI (1.1±0.3%) (Wilcoxon two sample test, W = 4756, p<0.001; Table 4). PorGAs were positively associated with the main Hawaiian Islands (Maui, Hawaii, Oahu, and Kauai) and the average prevalence of PorGAs was significantly higher in the MHI (0.64±0.15%) as compared to the NWHI (0.32±0.3%) (Wilcoxon two sample test, W = 3177, p<0.001; Table 4). The patterns of PorTLS prevalence were more difficult to interpret but seemed to be positively associated with some islands within the Northwestern Hawaiian Islands (Pearl and Hermes, and to a lesser extent French Frigate Shoals, Kure, Lisianski, Laysan and Maro), but negatively associated with other islands (Midway and Gardner) and the islands of Niihau and Lehua within the MHI (Fig. 4). Average prevalence of PorTLS did not differ between regions (Wilcoxon two sample test, W = 4990, p = 0.08; Table 4).


Patterns of coral disease across the Hawaiian archipelago: relating disease to environment.

Aeby GS, Williams GJ, Franklin EC, Kenyon J, Cox EF, Coles S, Work TM - PLoS ONE (2011)

Constrained CAP ordination of coral disease assemblages for 136 sites at 14 islands across the Hawaiian archipelago.Group centroids are displayed for each island (MHI – black, NWHI – red). Ordination is based on a zero-adjusted Bray-Curtis coefficient. Bi-plot indicates the disease variables (vectors) exerting the strongest influence on the patterns in multivariate space (in grey). The length and direction of each vector indicates the strength and sign, respectively, of the relationship between that disease variable and the CAP axes. Note that Acropora diseases are not included in the analysis. FFS, French Frigate Shoals; P&H, Pearl and Hermes. PorTrem, Porites trematodiasis; PorTL, Porites tissue loss; PorGA, Porites growth anomalies.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105043&req=5

pone-0020370-g004: Constrained CAP ordination of coral disease assemblages for 136 sites at 14 islands across the Hawaiian archipelago.Group centroids are displayed for each island (MHI – black, NWHI – red). Ordination is based on a zero-adjusted Bray-Curtis coefficient. Bi-plot indicates the disease variables (vectors) exerting the strongest influence on the patterns in multivariate space (in grey). The length and direction of each vector indicates the strength and sign, respectively, of the relationship between that disease variable and the CAP axes. Note that Acropora diseases are not included in the analysis. FFS, French Frigate Shoals; P&H, Pearl and Hermes. PorTrem, Porites trematodiasis; PorTL, Porites tissue loss; PorGA, Porites growth anomalies.
Mentions: Disease assemblages differed significantly between regions (Pseudo-F = 9.905, P = 0.0001), with three diseases, Porites trematodiasis (PorTrem), Porites growth anomalies (PorGA), and Porites tissue loss syndrome (PorTL) contributing most strongly to driving this separation (Fig. 4). Increased levels of PorTrem were associated with the Northwestern Hawaiian Islands (French Frigate Shoals, Kure, Maro, Laysan and Lisianski) and average prevalence of PorTrem was significantly higher in the NWHI (10.7±2.2%) compared to the MHI (1.1±0.3%) (Wilcoxon two sample test, W = 4756, p<0.001; Table 4). PorGAs were positively associated with the main Hawaiian Islands (Maui, Hawaii, Oahu, and Kauai) and the average prevalence of PorGAs was significantly higher in the MHI (0.64±0.15%) as compared to the NWHI (0.32±0.3%) (Wilcoxon two sample test, W = 3177, p<0.001; Table 4). The patterns of PorTLS prevalence were more difficult to interpret but seemed to be positively associated with some islands within the Northwestern Hawaiian Islands (Pearl and Hermes, and to a lesser extent French Frigate Shoals, Kure, Lisianski, Laysan and Maro), but negatively associated with other islands (Midway and Gardner) and the islands of Niihau and Lehua within the MHI (Fig. 4). Average prevalence of PorTLS did not differ between regions (Wilcoxon two sample test, W = 4990, p = 0.08; Table 4).

Bottom Line: These results highlight the importance of understanding disease ecology when interpreting patterns of disease occurrence.In contrast, the high occurrence of PorGAs within the MHI suggests that PorGAs are related, directly or indirectly, to some environmental co-factor associated with increased human population sizes.The association with human population density differed among disease states with PorGAs showing a positive and PorTrm showing a negative association, but no significant explanatory power was offered for PorTLS.

View Article: PubMed Central - PubMed

Affiliation: Hawai'i Institute of Marine Biology, University of Hawaii, Kaneohe, Hawai'i, United States of America. greta@hawaii.edu

ABSTRACT
In Hawaii, coral reefs occur across a gradient of biological (host abundance), climatic (sea surface temperature anomalies) and anthropogenic conditions from the human-impacted reefs of the main Hawaiian Islands (MHI) to the pristine reefs of the northwestern Hawaiian Islands (NWHI). Coral disease surveys were conducted at 142 sites from across the Archipelago and disease patterns examined. Twelve diseases were recorded from three coral genera (Porites, Montipora, Acropora) with Porites having the highest prevalence. Porites growth anomalies (PorGAs) were significantly more prevalent within and indicative of reefs in the MHI and Porites trematodiasis (PorTrm) was significantly more prevalent within and indicative of reefs in the NWHI. Porites tissue loss syndrome (PorTLS) was also important in driving regional differences but that relationship was less clear. These results highlight the importance of understanding disease ecology when interpreting patterns of disease occurrence. PorTrm is caused by a parasitic flatworm that utilizes multiple hosts during its life cycle (fish, mollusk and coral). All three hosts must be present for the disease to occur and higher host abundance leads to higher disease prevalence. Thus, a high prevalence of PorTrm on Hawaiian reefs would be an indicator of a healthy coral reef ecosystem. In contrast, the high occurrence of PorGAs within the MHI suggests that PorGAs are related, directly or indirectly, to some environmental co-factor associated with increased human population sizes. Focusing on the three indicator diseases (PorGAs, PorTrm, PorTLS) we used statistical modeling to examine the underlying associations between disease prevalence and 14 different predictor variables (biotic and abiotic). All three diseases showed positive associations with host abundance and negative associations with thermal stress. The association with human population density differed among disease states with PorGAs showing a positive and PorTrm showing a negative association, but no significant explanatory power was offered for PorTLS.

Show MeSH
Related in: MedlinePlus