JU marine science students, faculty present on ocean habitats at Benthic Ecology Meeting

By Taylor Agnew

JU Communications senior

JU faculty and students recently presented at the Benthic Ecology Meeting in Jacksonville, one of the largest scientific gatherings of premier marine biologists in the world.

The team made a strong showing with three posters, said Dr. Dan McCarthy, director of the Marine Science Program at Jacksonville University. 

“This is a chance to see cutting-edge marine science and develop research ideas,” he said.

The JU contingent consisted of one undergraduate student (Krystal Dannenhoffer); one graduate student (Alex Paradise); and three faculty (McCarthy, Lee Ann Clements and Jeremy Stalker). McCarthy also chaired the meeting’s Community Ecology session.

The 43rd BEM meeting March 19-22 was hosted by the University of North Florida and brought more than 600 registrants, a mix of the nation’s top marine ecologists and up-and-coming graduate and undergraduate students. 

A summary of presentations and posters by JU’s faculty and students is below, with JU undergraduate students in bold: 

POSTERS

A comparison of algal communities on nearshore natural and artificial reefs in Palm Beach County, Florida

Dan McCarthy, Jacksonville University

Shallow hard-bottom habitats along the east Florida coast harbor a high diversity and abundance of fish and invertebrates. These habitats often need to be mitigated when they are covered by sand during beach restoration projects. It is unclear how well currently used artificial reefs (often deployed in deeper water) restore the ecological function of lost habitat. As part of a larger state-funded project, this study compared the algal communities encountered in artificial versus natural habitats at four depths (0-1, 1-2, 2-3 & 3-4 m) during six surveys that were conducted from 2009 to 2013. Over 800 quadrats were sampled for macroalgae within natural and artificial reefs in Palm Beach County, Florida.  Most samples contained turf algae, but some also contained larger macroalgae.  Algal richness and biomass were statistically highest (p=0.001) at natural versus artificial reefs at the two shallowest depths sampled. Natural reefs also contained higher abundances of coarsely branched taxa than their artificial counterparts (p=0.001).  These results suggest that future mitigation reefs in this area should be placed at depths similar to those of the habitats lost. It also suggests that natural algae communities in these highly disturbed habitats may persist longer than previously thought.

A comparison of algae-associated invertebrate communities in natural vs. artificial hard-bottom habitat in Palm Beach County, Fla.

Krystal Dannenhoffer; Dan McCarthy, Jacksonville University

Along the east Florida coast there are shallow hard-bottom habitats that harbor a high diversity and abundance of fish and invertebrates. They often need to be mitigated due to beach restoration projects that cover them with sand. As part of a larger state funded project, this study compares the algae-associated invertebrates encountered in natural versus artificial habitats at four depths (0-1, 1-2, 2-3 & 3-4 m) during five surveys that were conducted from 2012 to 2013.  Over 650 algal samples were collected from natural and artificial hard bottom habitats in Palm Beach County, FL. Over 8,100 individual invertebrates were collected and identified from the surveys, representing 131 taxa. Amphipods represented over 30 percent of all invertebrates within natural and artificial habitats, whereas polychaetes, sipunculans, and gastropods composed 11-18 percent. Invertebrate number and richness were statistically higher on natural versus artificial reefs at the shallowest depth tested. Multivariate analyses revealed differences in species composition with survey and reef type (p<0.05). Most of these observed differences were attributable to variation in abundance and diversity of mollusks. Considering the importance of algae-associated invertebrates trophically and in enhancing biodiversity, future reef mitigation efforts should occur in shallow water to more effectively restore lost habitats.

Stability of a soft-bottom community: impacts and recovery following dredging disturbance off Amelia Island, Florida

Alex Paradise; Dan McCarthy, Jacksonville University

Offshore dredging has the potential to drastically impact benthic infaunal communities. It is necessary to investigate the degree and rate of recovery in these communities to gain insight into short- and long-term impacts of such disturbances. Trends in benthic fauna abundance and diversity were monitored following the 2011 excavation of an offshore sediment deposit off Amelia Island, Fla. Sediment samples were collected from five excavated sites and five non-excavated control sites in 2011 prior to excavation, and afterward during 2012 and 2013. Initial analyses of year one post-excavation show no significant differences in faunal density between borrow and control sites. There were significant decreases in mean species richness in excavated sites, yet no trends at control sites. Further, while infaunal density decreased significantly in control sites after one year, high variation at borrow sites obscured any potential trends. However by, 2013 (two years post excavation), infaunal density and species richness declined significantly at only excavated sites. Observed temporal trends in infauna may have resulted from the combined effects of the dredging disturbance and an influx of fine fluvial sediments over time from a neighboring river creating anoxic conditions that ultimately adversely affected the benthic community.