Title

The Ups and Downs of Coral Reef Fishes: The Genetic Characteristics of a Formerly Severely Overfished but Currently Recovering Nassau Grouper Fish Spawning Aggregation

Document Type

Article

Publication Date

3-2016

Publication Title

Coral Reefs

Keywords

Nassau grouper, Microsatellite, Fish spawning aggregation, Bottleneck, Population recovery

ISSN

0722-4028

Volume

35

Issue/No.

1

First Page

273

Last Page

284

Abstract

The Nassau grouper (Epinephelus striatus) has sustained large declines across its distribution, including extirpation of many of its fish spawning aggregations (FSAs). Within US Virgin Islands (USVI) waters, Nassau grouper FSAs were overfished until their disappearance in the 1970s and 1980s. In the early 2000s, however, Nassau grouper were found gathering at Grammanik Bank, USVI, a mesophotic coral reef adjacent to one of the extinct aggregation sites, and regulatory protective measures were implemented to protect this fledgling FSA. The population genetic dynamics of this rapid FSA deterioration followed by protection-facilitated, incipient recovery are unknown. We addressed two objectives: (1) we explored which factors (i.e., local vs. external recruitment) might be key in shaping the USVI FSA recovery; and (2) we examined the consequences of severe past overfishing on this FSA’s current genetic status. We genotyped individuals (15 microsatellites) from the USVI FSA comprising three successive spawning years (2008–2010), as well as individuals from a much larger, presumably less impacted, Nassau grouper FSA in the Cayman Islands, to assess their comparative population dynamics. No population structure was detected between the USVI and Cayman FSAs (FST = −0.0004); however, a temporally waning, genetic bottleneck signal was detected in the USVI FSA. Parentage analysis failed to identify any parent–offspring matches between USVI FSA adults and nearby juveniles, and relatedness analysis showed low levels of genetic relatedness among USVI FSA individuals. Genetic diversity across USVI FSA temporal collections was relatively high, and no marked differences were found between the USVI and Cayman FSAs. These collective results suggest that external recruitment is an important driver of the USVI FSA recovery. Furthermore, despite an apparent genetic bottleneck, the genetic diversity of USVI Nassau grouper has not been severely compromised. Our findings also provide a baseline for future genetic monitoring of the nascent USVI aggregation.

Comments

©Springer-Verlag Berlin Heidelberg 2015

Additional Comments

NOAA Award #: NA12NOS4260144; Us Geological Survey State Partnership Program #: 07ERAG0078; Puerto Rico Sea Grant #: R-31-746 1-06

ResearcherID

G-4080-2013

DOI

10.1007/s00338-015-1370-3

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