Brittany Huntington | NOAA Fisheries, Pacific Islands Fisheries Science Center (original) (raw)

Papers by Brittany Huntington

Coral reef restoration methods such as coral gardening are becoming increasingly considered as vi... more Coral reef restoration methods such as coral gardening are becoming increasingly considered as viable options to mitigate reef degradation and enhance recovery of depleted coral populations. In this study, we describe several aspects of the coral gardening approach that demonstrate this methodology is an effective way of propagating the threatened Caribbean staghorn coral Acropora cervicornis: (1) the growth of colonies within the nursery exceeded the growth rates of wild staghorn colonies in the same region; (2) the collection of branch tips did not result in any further mortality to the donor colonies beyond the coral removed for transplantation; (3) decreases in linear extension of the donor branches were only temporary and donor branches grew faster than control branches after an initial recovery period of approximately 3–6 weeks; (4) fragmentation did not affect the growth rates of non-donor branches within the same colony; (5) small branch tips experienced initial mortality due to handling and transportation but surviving tips grew well over time; and (6) when the growth of the branch tips is added to the regrowth of the fragmented donor branches, the new coral produced was 1.4–1.8 times more than new growth in undisturbed colonies. Based on these results, the collection of small (2.5–3.5 cm) branch tips was an effective propagation method for this branching coral species resulting in increased biomass accumulation and limited damage to parental stocks.

The staghorn coral Acropora cervicornis is a branching coral with complex morphology. While this ... more The staghorn coral Acropora cervicornis is a branching coral with complex morphology.
While this structural complexity confers high ecological and habitat value, it hinders accurate
quantification. An appropriate and quantitative coral ‘unit’ is required to effectively implement
protective provisions (e.g. prevention of take or strategies to meet quantitative recovery criteria)
for A. cervicornis under the United States Endangered Species Act. Actual measurements of 3-
dimensional structure or extent of branches within colonies are time-consuming and therefore not
feasible for monitoring application. This study calibrated arduous in-water measurements of total
linear extent (TLE, sum of all branch lengths in a fully live colony, intuitively representing the
‘amount’ of coral in an individual colony) to more manageable standard field measurements of
colony dimensions or photographs. The robustness of this relationship was then evaluated among
colonies of different origin (wild, nursery-reared, transplanted) and different habitats (patch reef,
shallow forereef, deep forereef) in the upper Florida Keys, USA. Within this sample set, colony volume
(calculated as an ellipsoid based on 3 colony dimensions) was highly predictive of TLE (r2 =
0.94 for log-log linear regression), and this relationship was consistent for colonies from different
origins and different reef habitats. Thus, ‘unit’ coral abundance at the colony scale in terms of
branch extent (TLE) can be reliably estimated from simple colony dimensions in the Florida Keys.
Additional data are required to determine if different calibrations are needed in other populations,
to adjust estimates for partial mortality of colonies, and to ‘scale up’ reliable estimates to thicketor
reef-scale.

The most common coral monitoring methods estimate coral abundance as percent cover, either via in... more The most common coral monitoring methods estimate coral abundance as percent cover, either via in situ observations or derived from images. In recent years, growing interest and effort has focused on colony-based (demographic) data to assess the status of coral populations and communities. In this study, we relied on two separate data sets (photo-derived percent cover estimates, 2002–12, and opportunistic in situ demographic sampling, 2004 and 2012) to more fully infer decadal changes in coral communities at a small, uninhabited Caribbean island. Photo-derived percent cover documented drastic declines in coral abundance including disproportionate declines in Orbicella spp. While overall in situ estimates of total coral density were not different between years, densities of several rarer taxa were. Meandrina meandrites and Stephanocoenia intersepta increased while Leptoseris cucullata decreased significantly, changes that were not discernable from the photo-derived cover estimates. Demographic data also showed significant shifts to larger colony sizes (both increased mean colony sizes and increased negative skewness of size frequency distributions, but similar maximum colony sizes) for most taxa likely indicating reduced recruitment. Orbicella spp. differed from this general pattern, significantly shifting to smaller colony sizes due to partial mortality. Both approaches detected significant decadal changes in coral community structure at Navassa, though the demographic sampling provided better resolution of more subtle, taxon-specific changes.

We developed a method for quantifying the abundance of the threatened staghorn coral (Acropora ce... more We developed a method for quantifying the abundance of the threatened staghorn coral (Acropora cervicornis) and evaluated the accuracy of commonly used methods to assess colony condition. For small-to medium-sized colonies, we show that colony ellipsoid volume estimated from simple colony dimensions serves as a reliable and efficient proxy for the more time-consuming, conventional measure of colony total linear extension, and that this predictive relationship varies significantly among extant populations in the Caribbean. We also determined that visual estimates of colony partial mortality closely approximate to true values for colonies with <25% mortality, with in situ estimates outperforming estimates from digital images. These results provide coral reef managers and restoration practitioners with guidance for assessing partial mortality and location-specific regression models to estimate " amount " of staghorn coral in both extant and restored staghorn populations in Belize, the United States Virgin Islands, and the Dry Tortugas National Park, Florida, U.S.A. As staghorn coral monitoring and restoration efforts continue to expand in the Caribbean, these methods for quickly determining staghorn abundance and condition will directly aid resource managers tasked with monitoring wild populations and tracking restoration success over time.

Landscape-scale attributes of patch size, spatial isolation, and topographic complexity are known... more Landscape-scale attributes of patch size, spatial isolation, and topographic complexity are known to influence diversity and abundance in terrestrial and marine systems, but remain collectively untested for reef-building corals. To investigate the relationship between the coral assemblage and seascape variation in reef habitats, we took advantage of the distinct boundaries, spatial configurations, and topographic complexities among artificial reef patches to overcome the difficulties of manipulating natural reefs. Reef size (m 2) was found to be the foremost predictor of coral richness in accordance with species-area relationship predictions. Larger reefs were also found to support significantly higher colony densities, enabling us to reject the null hypothesis of random placement (a sampling artifact) in favor of target area predictions that suggest greater rates of immigration on larger reefs. Unlike the pattern previously documented for reef fishes, topographic complexity was not a significant predictor of any coral assemblage response variable, despite the range of complexity values sampled. Lastly, coral colony density was best explained by both increasing reef size and decreasing reef spatial isolation, a pattern found exclusively among brooding species with shorter larval dispersal distances. We conclude that seascape attributes of reef size and spatial configuration within the seascape can influence the species richness and abundance of the coral community at relatively small spatial scales (\1 km). Specifically, we demonstrate how patterns in the coral communities that have naturally established on these manipulated reefs agree with the target area and island biogeography mechanisms to drive species-area relationships in reef-building corals. Based on the patterns documented in artificial reefs, habitat degradation that results in smaller, more isolated natural reefs may compromise coral diversity.

To determine the effects of algal reduction and fisheries closure, a crossed experimental design ... more To determine the effects of algal reduction and fisheries closure, a crossed experimental
design was undertaken over a 516 d period on the remote patch reefs of Glover’s Reef
Atoll, Belize. We investigated (1) the effects on health, growth, and survivorship of 2 transplanted
coral species, Porites asteroides and Siderastrea siderea, and (2) the changes in the benthic and
fish communities. Algal reduction (98% reduction by physical removal kept low by monthly
removal) increased the abundance of all fish and slightly elevated herbivore bite rates. P. asteroides
showed a temporal response to environmental conditions opposite of predictions, with
higher bleaching and mortality in the unfished reefs cleared of algae. This may be due to reduced
water flow at these sites as the growth rate of P. asteroides was positively related to water flow
(R2 = 0.35, p = 0.04). S. siderea growth showed no relationship with water flow and bleached
slightly more in the control reefs. Nevertheless, there were no patterns in mortality, and growth
rates were twice as high in the fished than unfished reefs for this species. This reef-scale study
contrasts with results of small-scale experiments that found rapid, indirect coral mortality from
erect algae. Rather, our results suggest that environmental conditions, notably reef location
in relation to water flow, can be a considerably stronger factor influencing coral health than
erect algae.

Abstract Recovery of the threatened staghorn coral (Acropora cervicornis) is posited to play a ke... more Abstract Recovery of the threatened staghorn coral (Acropora
cervicornis) is posited to play a key role in Caribbean
reef resilience. At four Caribbean locations (including one
restored and three extant populations), we quantified characteristics
of contemporary staghorn coral across increasing
conspecific densities, and investigated a hypothesis of
facilitation between staghorn coral and reef fishes. High
staghorn densities in the Dry Tortugas exhibited significantly
less partial mortality, higher branch growth, and supported
greater fish abundances compared to lower densities
within the same population. In contrast, partial mortality,
branch growth, and fish community composition did not
vary with staghorn density at the three other study locations
where staghorn densities were lower overall. This
suggests that density-dependent effects between the coral
and fish community may only manifest at high staghorn
densities. We then evaluated one facilitative mechanism for
such density-dependence, whereby abundant fishes sheltering
in dense staghorn aggregations deliver nutrients back to
the coral, fueling faster coral growth, thereby creating more
fish habitat. Indeed, dense staghorn aggregations within the Dry Tortugas exhibited significantly higher growth rates,
tissue nitrogen, and zooxanthellae densities than sparse
aggregations. Similarly, higher tissue nitrogen was induced
in a macroalgae bioassay outplanted into the same dense
and sparse aggregations, confirming greater bioavailability
of nutrients at high staghorn densities. Our findings inform
staghorn restoration efforts, suggesting that the most effective
targets may be higher coral densities than previously
thought. These coral-dense aggregations may reap the benefits
of positive facilitation between the staghorn and fish
community, favoring the growth and survivorship of this
threatened species.

Rocky reefs in the temperate Northeast Pacific constitute a small portion of the nearshore seabed... more Rocky reefs in the temperate Northeast Pacific constitute a small portion of the nearshore seabed, yet are highly valued as productive habitat for local fisheries. Surveying these structurally complex, untrawlable habitats requires robust gear that can be deployed in rough sea states. Here, a cost-effective, compact video lander was evaluated for its ability to survey the diversity and abundance of nearshore (b40 m), rocky-reef-associated fish populations (e.g. Sebastes, Cottidae, Hexagrammidae). To determine the application and limitations of surveying complex rocky reefs with this new tool, this study sought to (1) determine the frequency of observation of known nearshore fish species, (2) evaluate the influence of baiting the lander on the observed fish assemblage, (3) identify the optimal deployment time to maximize observed species richness and abundance, and (4) evaluate species specific behavioral responses to the lander characterized a priori as attractive, avoidance, or neutral. Seventy percent of lander deployments met established requirements of visibility, view, and habitat. Seventy-seven percent of observed fishes were identifiable to species. The method observed 15 species belonging to 5 families; 5 species were classified as common (observed in N20% of deployments), the remaining rare. Contrary to lander studies in other regions, bait was not found to improve species-specific identification, increase observed species richness or abundance (at the species or feeding guild level), or shorten deployment duration. A deployment time of 8 min on the benthos was determined as optimal for observing maximum species richness and abundance in the nearshore, doubling the previously described lander drop durations evaluated in deeper Oregon, U.S.A., waters. Species-specific behavioral responses to this compact lander were evaluated by viewing trends in species abundance (assessed within 30 s bins) over the deployment duration; no attractive or avoidance behaviors were observed. Results confirm that this simple, cost-effective video lander configuration is suitable for sampling the suite of fish species found in the nearshore, including rockfish species federally designated as " overfished " (Sebastes pinniger and Sebastes ruberrimus). Furthermore, this study illustrates the importance of evaluating the performance of survey tools in the specific environment in which the tool will be used to determine best-practices from long-term monitoring.

Pelagic dispersal of most benthic marine organisms is a fundamental driver of population distribu... more Pelagic dispersal of most benthic marine organisms is a fundamental driver of population distribution and persistence and is thought to lead to highly mixed populations. However, the mechanisms driving dispersal pathways of larvae along open coastlines are largely unknown. To examine the degree to which early stages can remain spatially coherent during dispersal, we measured genetic relatedness within a large pulse of newly recruited splitnose rockfish (Sebastes diploproa), a live-bearing fish whose offspring settle along the US Pacific Northwest coast after spending up to a year in the pelagic environment. A total of 11.6% of the recruits in a single recruitment pulse were siblings, providing the first evidence for persistent aggregation throughout a long dispersal period. Such protracted aggregation has profound implications for our understanding of larval dispersal, population connectivity, and gene flow within demersal marine populations.

We describe spatial patterns in fish abundance across the lagoonal patch reef system at Glover's ... more We describe spatial patterns in fish abundance across the lagoonal patch reef system at Glover's Reef Atoll in Belize, and assess the relative influence of physical, biological, and abiotic structural variables on these patterns. Physical factors—specifically, distance from reef channels, current flow, and temperature—play a significant role in structuring overall patterns in fish abundance across the lagoon. The types of variables that best explained trends in abundance of specific groups of fishes were related to feeding habits of these groups. For example, fishes dependent on primary and secondary sources of productivity (herbivores and planktivores) were most highly influenced by physical factors. Abundances of benthophagous fishes were best predicted by benthic habitat variables such as coral cover, while abundance of piscivorous fish groups was best predicted by abiotic structural habitat variables such as reef area. While data on physical oceanographic properties are not normally considered in relation to abundance patterns of reef fishes, we find that such factors are good predictors of abundance for these species. Where physical data are not available, simple distance metrics may serve as reasonable proxies for physical oceanographic processes.

Marine Pollution Bulletin, Jan 1, 2012

Debris removal programs are combatting the accumulation of derelict fishing gear and other debris... more Debris removal programs are combatting the accumulation of derelict fishing gear and other debris in marine habitats. We analyzed 5 years of lobster trap debris removal data in Biscayne National Park, Florida to assess removal efficiency and develop spatially-explicit mapping tools to guide future removals. We generated and validated debris ''hot spots'' maps that combined remotely-sensed data (i.e. benthic habitat type and bathymetry) with 862 locations of previous debris collection. Our hot spot models spatially depict regions of likely debris accumulation, reducing the search area by 95% (from 332 km 2 to 18 km 2 ) and encompassing 100% of the validation sites. Our analyses indicate removal contractors using sub-surface towed divers enhanced debris recovery. Additionally, the quantity of debris removed did not decrease with increased efforts, suggesting that debris supply in situ exceeds removal efforts. We conclude with the importance of coupling analysis of ongoing debris removal programs with GIS technology to improve removal efforts.

Freshwater …, Jan 1, 2011

1. Ecologists continue to debate whether the assembly of communities of species is more strongly ... more 1. Ecologists continue to debate whether the assembly of communities of species is more strongly influenced by dispersal limitations or niche-based factors. Analytical approaches that account for both mechanisms can help to resolve controls of community assembly. 2. We compared littoral snail assemblages in Lake Tanganyika at three different spatial scales (5-25 m, 0.5-10 km and 0.5-27 km) to test whether spatial distance or environmental differences are better predictors of community similarity. 3. At the finest scale (5-25 m), snail assemblages shifted strongly with depth but not across similar lateral distances, indicating a stronger response to environmental gradients than dispersal opportunities. 4. At the two larger scales (0.5-27 km), both environmental similarity and shoreline distance between sites predicted assemblage similarity across sites. Additionally, canonical correspondence analysis revealed that snail abundances were significantly correlated with algal carbon-to-nitrogen ratio and wave energy. 5. Our results indicate that the factors governing assemblage structure are scale dependent; niche-based mechanisms act across all spatial scales, whereas community similarity declines with distance only at larger spatial separations.

of a dissertation at the University of Miami. Dissertation supervised by Assistant Professor Dieg... more of a dissertation at the University of Miami. Dissertation supervised by Assistant Professor Diego Lirman. No. of pages in text. (177)

Environmental Bioindicators, Jan 1, 2008

Through bioassay techniques and field collections of red macroalgae (Gracilariopsis sp.) and eelg... more Through bioassay techniques and field collections of red macroalgae (Gracilariopsis sp.) and eelgrass (Zostera marina), we evaluated growth, tissue %Nitrogen (N) and N stable isotopic signatures as bioindicators of potential changes in N supply to Tomales Bay, CA (USA). Gracilariopsis sp. collected, cultured, and outplanted across a spatial gradient in Tomales Bay showed pronounced changes in N patterns from past studies in this system, and was superior to field collections in detecting spatial N signals. Rather than a single peak in N concentration near the oceanic source found in previous work, we detected two N peaks, one near the bay head and one near the bay mouth. This spatial pattern suggests two sources account for these discrete regions of increased N supply. The temporal N patterns showed marked seasonality, with greater tissue N concentration during the wet season and reduced N concentrations during the dry season. The spatial patterns presented here suggest shifting nutrient dynamics within Tomales Bay, with increased N supply detected near the major watershed inflow. Nitrogen isotopic values suggest an enriched wastewater source, but additional work is needed to confirm the source of this newly reported N signal.

Frontiers in Ecology and the …, Jan 1, 2011

Limnol. Oceanogr. Methods, Jan 1, 2012

Marine Ecology Progress Series, Jan 1, 2008

Observations of increasing red macroalgal (Gracilariopsis sp.) abundance in Tomales Bay, Californ... more Observations of increasing red macroalgal (Gracilariopsis sp.) abundance in Tomales Bay, California (USA) prompted a field survey and an in situ experiment testing algal mat effects on eelgrass (Zostera marina) growth. At the conclusion of a 3 mo macroalgal enclosure/exclosure study, experimental plots containing high macroalgal loads (1700 g m -2 wet weight = mean maximum in a field survey) had significantly lower Z. marina shoot densities and growth rates than plots with no algae or with mean algal field abundance (325 g m -2 ). Eelgrass aboveground biomass followed a similar trend, decreasing under high macroalgal loads. We explored possible mechanisms of algal impacts on eelgrass, including changes to redox potential, sediment nitrogen, and light. Of these, light limitation is the most likely explanation for decreases in eelgrass shoot density. Light reaching the benthos where new shoots establish was only 2% of surface irradiance under high algal loads, while the canopy of adult eelgrass shoots received nearly 40% of surface irradiance regardless of macroalgal abundance. Reduced Z. marina growth rates may also be attributable to light limitation, as light levels neared the compensation irradiance for eelgrass under high macroalgal loads. Phase shifts from seagrass to macroalgae have been well documented in other estuaries, although studies are generally conducted well after the shift to macroalgal dominance has occurred. Our results indicate a similar transition is possible in Tomales Bay and suggest the need to monitor and manage this system prior to a future shift.

PloS one, Jan 1, 2010

Distinguishing management effects from the inherent variability in a system is a key consideratio... more Distinguishing management effects from the inherent variability in a system is a key consideration in assessing reserve efficacy. Here, we demonstrate how seascape heterogeneity, defined as the spatial configuration and composition of coral reef habitats, can mask our ability to discern reserve effects. We then test the application of a landscape approach, utilizing advances in benthic habitat mapping and GIS techniques, to quantify this heterogeneity and alleviate the confounding influence during reserve assessment. Seascape metrics were quantified at multiple spatial scales using a combination of spatial image analysis and in situ surveys at 87 patch reef sites in Glover's Reef Lagoon, Belize, within and outside a marine reserve enforced since 1998. Patch reef sites were then clustered into classes sharing similar seascape attributes using metrics that correlated significantly to observed variations in both fish and coral communities. When the efficacy of the marine reserve was assessed without including landscape attributes, no reserve effects were detected in the diversity and abundance of fish and coral communities, despite 10 years of management protection. However, grouping sites based on landscape attributes revealed significant reserve effects between site classes. Fish had higher total biomass (1.56) and commercially important biomass (1.756) inside the reserve and coral cover was 1.8 times greater inside the reserve, though direction and degree of response varied by seascape class. Our findings show that the application of a landscape classification approach vastly improves our ability to evaluate the efficacy of marine reserves by controlling for confounding effects of seascape heterogeneity and suggests that landscape heterogeneity should be considered in future reserve design.

Marine Pollution Bulletin, Jan 1, 2012

Freshwater …, Jan 1, 2011

Environmental Bioindicators, Jan 1, 2008

Frontiers in Ecology and the …, Jan 1, 2011

Limnol. Oceanogr. Methods, Jan 1, 2012

Marine Ecology Progress Series, Jan 1, 2008

PloS one, Jan 1, 2010