Showing papers by "Charles H. Peterson published in 2013"
TL;DR: It is indicated that seeding does not enhance oyster reef restora- tion efforts in Pamlico Sound and the need to quantify basic ecological processes on appropriate spatiotemporal scales should underlie restoration planning for other biogenic habitats like seagrass meadows and coral reefs.
Abstract: Oyster reefs are one of the most depleted and degraded marine habitats worldwide. To reverse the current oyster reef declines, governmental and private organizations have invested substantial resources into oyster restoration. Restoration primarily consists of deploying hard substrate. If oyster recruitment is thought to be limited, hatchery-raised juvenile oysters are set on the hard substrate. These costly setting efforts are carried out despite limited information on whether seed oysters accelerate reef development and, if so, how oyster size and time of deploy- ment maximize oyster survival. North Carolina, USA, has established subtidal oyster sanctuaries in Pamlico Sound using marl mounds and hatchery-raised juvenile oysters set on recycled shell. We experimentally manipulated marl mounds at 3 sanctuaries differing abiotically and biotically during summer 2010 and varied recycled shell and seed presence, seed size, and shell and seed deployment date. Although oyster settlement varied spatially, natural recruitment swamped any measurable effect of seeding. Our findings, in combination with information from 3 additional sanctuaries seeded in 2006 and 2008, indicate that seeding does not enhance oyster reef restora- tion efforts in Pamlico Sound. Financial resources used for oyster seed would be better used to increase the amount of substrate for oyster settlement. Although our results may not apply to areas with less natural oyster recruitment, our study highlights the need to quantify basic ecological processes on appropriate spatiotemporal scales to optimize restoration actions. Analogous infor- mation should underlie restoration planning for other biogenic habitats like seagrass meadows and coral reefs.
39 citations
TL;DR: It is shown that coarse shell fragments and other large particles persist as a press disturbance for years after the nourishment ends, and elevated silts/clays can become resuspended by erosive wind events in repeated pulse disturbances for at least months afterward, in each case reflecting demonstrable long-term degradation of sandy-beach foraging habitat for surf fish.
Abstract: Novel wave-tank mesocosms allowed hydrodynamically realistic tests of how sediment modifications affect feeding by a surf fish, Florida pompano, Trachinotus carolinus (Linnaeus, 1766). Pompano demonstrated visually based selection, preferentially preying on bean clams, Donax variabilis Say, 1822, colored in contrast with background. Pompano often took shell into their mouths instead of live bean clams. Sediments of nourished Bogue Banks (North Carolina) beaches exhibited >2.5-yr persistence of elevated coarse shell content at levels that suppressed pompano feeding in wave tanks. Elevated turbidity 4-8 mo after nourishment indicated that wave-induced erosion of buried fine sediments in sacrificial beach fill resulted in repeated turbidity events, reaching levels that in wave tanks reduced pompano feeding on Donax and mole crabs, Emerita talpoida (Say, 1817). Burial speeds of these prey in the beach swash zone were progressively reduced by increasing shell concentrations. Reduced burial rates reduce feeding opportunity and expose these mobile invertebrates to greater risk of wave transport out of the swash-zone habitat. Sampling six beaches revealed that density of Donax decreased linearly with increasing sediment size and shell concentration. Beyond the immediate mass mortality of invertebrate prey caused by >1 m of sediment deposition during beach filling, coarse shell fragments and other large particles persist as a press disturbance for years after the nourishment ends, and elevated silts/clays can become resuspended by erosive wind events in repeated pulse disturbances for at least months afterward, in each case reflecting demonstrable long-term degradation of sandy-beach foraging habitat for surf fish.
26 citations
TL;DR: It is shown that a 2.6-fold higher ghost crab density resulted in 5 times more nocturnal threat encounters with sliders and 3.4 times more slider captures, implying predator dilution.
Abstract: Protecting eggs from predators is common practice in sea turtle conservation, but routine protection of hatchlings is not. Of 42 loggerhead hatchlings observed emerging from 10 nests on undeveloped Onslow Beach, North Carolina, 24 % were preyed on by ghost crabs. In experimental trials, ghost crabs similarly threatened and captured neonate freshwater sliders, supporting their substitution as proxy for threatened and endangered sea turtle hatchlings in field experiments testing density dependence. Exploiting natural long-shore variation in ghost crab density, we show that a 2.6-fold higher ghost crab density resulted in 5 times more nocturnal threat encounters with sliders and 3.4 times more slider captures. Sliders released in simulated group emergences experienced lower per capita capture risk by ghost crabs than solitary sliders, implying predator dilution. Non-independence of egg and hatchling depredation motivates consideration of merging sea turtle egg and hatchling stages when modeling and managing food web interactions.
19 citations
TL;DR: The findings suggest that different planting schemes can be used to meet specific goals of restoration (e.g., accelerate plant recovery while suppressing colonization of non-planted species).
Abstract: Plant species richness can increase primary production because plants occupy different niches or facilitate each other (“complementarity effects”) or because diverse mixtures have a greater chance of having more productive species (“selection effects”). To determine how complementarity and selection influence dune restoration, we established four types of plant communities [monocultures of sea oats (Uniola paniculata), bitter panicgrass (Panicum amarum) and saltmeadow cordgrass (Spartina patens) and the three-species mixture] under different soil treatments typical of dune restorations (addition of soil organic material, nutrients, both, or neither). This fully factorial design allowed us to determine if plant identity, diversity and soil treatments influenced the yield of both the planted species and species that recruited naturally (volunteers). Planted species responses in monocultures and mixtures varied among soil treatments. The composition of the plantings and soils also influenced the abundance of volunteers. The mixture of the three species had the lowest cover of volunteers. We also found that the effect of diversity on production increased with fertilizer. We partitioned the biodiversity effect into complementarity and selection effects and found that the increase in the diversity effect occurred because increased nutrients decreased dominance by the largest species and increased complementarity among species. Our findings suggest that different planting schemes can be used to meet specific goals of restoration (e.g., accelerate plant recovery while suppressing colonization of non-planted species).
14 citations
TL;DR: This article found that species richness and evenness were low on the filled area relative to adjacent plant communities that had persisted through the storm, and there were no signs of establishing the typical zonation of back dune grasses, shrubs, and salt marsh.
Abstract: In September 2003, Hurricane Isabel created an inlet over 500 m wide and 10 m deep that connected the Atlantic Ocean and Pamlico Sound. This breach was subsequently filled with sediments dredged from the adjacent sound. The purpose of this study was to determine if the barrier island terrestrial plant communities were naturally re-establishing through primary succession. In 2006–2008, we compared plant communities, soil carbon and nitrogen, and Aeolian transport of sediments in undisturbed back-dunes, undisturbed shrub thickets, putative back-dunes, and putative shrub thickets. We found that species richness and evenness were low on the filled area relative to adjacent plant communities that had persisted through the storm. Plants on the filled area were almost entirely limited to a band of primarily Spartina patens found at the margin of the sound and there were no signs of establishing the typical zonation of back dune grasses, shrubs, and salt marsh. Evaluation of soil quality suggests that nutrients and organic material are not limiting recovery. Aeolian transport, however, was demonstrably higher across the filled area, where no dense stands of taller plants buffered the airflow. Plant re-establishment is suppressed by wind erosion inhibiting deposition of seeds. Recovery of the site will likely depend on the rhizomatous spread of S. patens from the sound shore. S. patens can then potentially facilitate the colonization of other species by buffering the wind and trapping seeds of other plants. Ironically, this slow recovery may benefit federally threatened bird species that require sparse vegetation for nesting success.
5 citations