Title

Investigating Pathogen Transmission Techniques and Genotypic Resistance in the Staghorn Coral, Acropora cervicornis

Location

Guy Harvey Oceanographic Center Facility

Start

1-31-2018 3:45 PM

End

1-31-2018 4:00 PM

Type of Presentation

Oral Presentation

Abstract

Unprecedented population losses of Acropora cervicornis since the 1970s have been attributed primarily to disease. Although a positive linear relationship between disease prevalence and increased water temperature has been described, the pathogens, vectors, and transmission of diseases affecting acroporid corals are still poorly understood. Due to an anticipated rise in disease outbreak and severity, a recent effort has been made to identify genotypic resistance to disease. However, prior to the present study, there has been no direct comparison between common pathogen transmission methods. We investigated transmission and resistance to disease in 11 different nursery-raised genotypes of A. cervicornis by comparing direct contact and water-borne transmission methods. Overall, transmission was highest in our direct contact treatment, though virulence of disease did not appear to be significantly different between treatments based on disease progression rates. Transmission varied greatly by genotype, with only one genotype appearing to be resistant to disease, showing no signs of disease throughout the study. However, histological analysis revealed that many fragments appeared to be in poor condition upon the start of our study, despite their visually healthy appearance. To determine if acclimation period affected tissue condition, we conducted a subsequent acclimation experiment over a 9-day period. Overall condition of fragments significantly worsened from day 0 to day 2, before significant improvements in surface-body tissue layers were observed at day 9. These results support the need for a longer acclimation period prior to pathogen exposure; a detail commonly overlooked in many disease-related study designs. Our results highlight the importance of selecting an appropriate disease transmission method and acclimation period when investigating genotypic resistance to disease in corals, and can help predict future population success of a local population.

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Jan 31st, 3:45 PM Jan 31st, 4:00 PM

Investigating Pathogen Transmission Techniques and Genotypic Resistance in the Staghorn Coral, Acropora cervicornis

Guy Harvey Oceanographic Center Facility

Unprecedented population losses of Acropora cervicornis since the 1970s have been attributed primarily to disease. Although a positive linear relationship between disease prevalence and increased water temperature has been described, the pathogens, vectors, and transmission of diseases affecting acroporid corals are still poorly understood. Due to an anticipated rise in disease outbreak and severity, a recent effort has been made to identify genotypic resistance to disease. However, prior to the present study, there has been no direct comparison between common pathogen transmission methods. We investigated transmission and resistance to disease in 11 different nursery-raised genotypes of A. cervicornis by comparing direct contact and water-borne transmission methods. Overall, transmission was highest in our direct contact treatment, though virulence of disease did not appear to be significantly different between treatments based on disease progression rates. Transmission varied greatly by genotype, with only one genotype appearing to be resistant to disease, showing no signs of disease throughout the study. However, histological analysis revealed that many fragments appeared to be in poor condition upon the start of our study, despite their visually healthy appearance. To determine if acclimation period affected tissue condition, we conducted a subsequent acclimation experiment over a 9-day period. Overall condition of fragments significantly worsened from day 0 to day 2, before significant improvements in surface-body tissue layers were observed at day 9. These results support the need for a longer acclimation period prior to pathogen exposure; a detail commonly overlooked in many disease-related study designs. Our results highlight the importance of selecting an appropriate disease transmission method and acclimation period when investigating genotypic resistance to disease in corals, and can help predict future population success of a local population.