Abstract

Sargassum mats are common features of South Florida coastlines. Consisting of pelagically drifting clumps of brown algae (usually of the genus Sargassum), these mats are critical nursery habitat for many fish species, providing surface shelter in otherwise exposed open ocean areas. However, the ecology of Sargassum mat communities remains unstudied. This project addressed two key knowledge gaps. First, the long term stability of Sargassum community structure was assessed in samples collected over an 8-year period. Overall 9 fish species were collected (N=150). Individual Sargassum mats typically harbored 2.6 ± 0.7 fish species which were equally abundant in any given sample (Pielou’s evenness 0.7 ± 0.2). Although cluster analyses distinguished two distinct groups of co-occurring species, overall community structure was stable across samples and did not vary as a function of collection month, season, or year (ANOSIM; 0Sargassum-associated fishes. Parasite communities included unidentified digenean metacercariae, copepods and acanthocephalans. Prevalence of infection with ≥ 1 parasite was 30% (45 of 150 fish examined) and mean intensity was 4.48 parasites per infected fish. This is consistent with parasitism rates in other critical nursery habitats such as mangroves but is much lower than is typical of similarly-sized openocean pelagic fishes not associated with Sargassum. Further research is needed to determine what processes drive low parasitism rates in fish nursery habitats.

Faculty Sponsors

Dr. Christopher Blanar, Dr. David Kerstetter

Project Type

Event

Location

Alvin Sherman Library

Start Date

4-7-2017 12:00 AM

End Date

4-7-2017 12:00 AM

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Apr 7th, 12:00 AM Apr 7th, 12:00 AM

Sargassum-associated Fish Communities are Stable Over Time and Feature Low Levels of Parasitism

Alvin Sherman Library

Sargassum mats are common features of South Florida coastlines. Consisting of pelagically drifting clumps of brown algae (usually of the genus Sargassum), these mats are critical nursery habitat for many fish species, providing surface shelter in otherwise exposed open ocean areas. However, the ecology of Sargassum mat communities remains unstudied. This project addressed two key knowledge gaps. First, the long term stability of Sargassum community structure was assessed in samples collected over an 8-year period. Overall 9 fish species were collected (N=150). Individual Sargassum mats typically harbored 2.6 ± 0.7 fish species which were equally abundant in any given sample (Pielou’s evenness 0.7 ± 0.2). Although cluster analyses distinguished two distinct groups of co-occurring species, overall community structure was stable across samples and did not vary as a function of collection month, season, or year (ANOSIM; 0Sargassum-associated fishes. Parasite communities included unidentified digenean metacercariae, copepods and acanthocephalans. Prevalence of infection with ≥ 1 parasite was 30% (45 of 150 fish examined) and mean intensity was 4.48 parasites per infected fish. This is consistent with parasitism rates in other critical nursery habitats such as mangroves but is much lower than is typical of similarly-sized openocean pelagic fishes not associated with Sargassum. Further research is needed to determine what processes drive low parasitism rates in fish nursery habitats.