Showing papers by "Charles H. Peterson published in 2014"

Integrating the invisible fabric of nature into fisheries management

Abstract: Overfishing and environmental change have triggered many severe and unexpected consequences. As existing communities have collapsed, new ones have become established, fundamentally transforming ecosystems to those that are often less productive for fisheries, more prone to cycles of booms and busts, and thus less manageable. We contend that the failure of fisheries science and management to anticipate these transformations results from a lack of appreciation for the nature, strength, complexity, and outcome of species interactions. Ecologists have come to understand that networks of interacting species exhibit nonlinear dynamics and feedback loops that can produce sudden and unexpected shifts. We argue that fisheries science and management must follow this lead by developing a sharper focus on species interactions and how disrupting these interactions can push ecosystems in which fisheries are embedded past their tipping points.

Open-coast sandy beaches and coastal dunes

Abstract: Coastal ecosystems are centres of high biological productivity, but their conservation is often threatened by numerous and complex environmental factors. Citing examples from the major littoral habitats worldwide, such as sandy beaches, salt marshes and mangrove swamps, this text characterises the biodiversity of coastline environments and highlights important aspects of their maintenance and preservation, aided by the analysis of key representative species. Leaders in the field provide reviews of the foremost threats to coastal networks, including the effects of climate change, invasive species and major pollution incidents such as oil spills. Further discussion underscores the intricacies of measuring and managing coastline species in the field, taking into account the difficulties in quantifying biodiversity loss due to indirect cascading effects and trophic skew. Synthesising the current state of species richness with present and projected environmental pressures, the book ultimately establishes a research agenda for implementing and improving conservation practices moving forward. [Book Synopsis]

Dominant macrobenthic populations experience sustained impacts from annual disposal of fine sediments on sandy beaches

Abstract: Despite increasing use of dredged mate- rials as beach fill to protect coastal property and public beaches from storm damage, knowledge of how this practice affects sandy beach ecosystems re- mains poor. We coupled field monitoring of 2 succes- sive beach disposal events with mesocosm experi- ments to assess mechanisms of ecological effects of fine sediment disposal. Macrobenthic sampling on Topsail Island, North Carolina, revealed that disposal of dredge spoils transformed beach grain sizes from medium to fine sand. Water sampling documented substantially elevated surf-zone turbidity during and occasionally after sediment deposition. When disposal occurred before spring invertebrate recruitment to the beach, it negatively influenced recruitment of the mole crab Emerita talpoida and the amphipod Para- haustorius longimerus. When disposal followed re- cruitment, it affected abundances of the bean clam Donax variabilis and 3 species of haustoriid am- phipods negatively, and abundance of the spionid polychaete Scolelepis squamata positively. Effects lasted for the full warm season, and suppressions of invertebrate abundances were repeated across suc- cessive annual disposal events. In mesocosms, turbid- ity matching that induced in the field slowed growth of clams and modified habitat choices by predatory fishes. Hence, annual disposal of fine-grained dredge spoils on these sandy beaches maintained depressed abundances of 5 of 6 macroinvertebrate prey of shore- bird and surf fish, without sustaining elevated volumes of beach sediments as long as a year. Implementation of disposal projects before the beginning of the sea- sonal recruitment of benthos resulted in fewer nega- tive impacts on abundance than disposal projects con- ducted after the recruitment season, probably reflecting a more universal risk from burial and suffocation.

Artificial substrates enhance non-native macroalga and N2 production

Abstract: The introduction of non-native species occurs within a context of other anthropogenic impacts: thus a holistic approach is needed to understand interactive effects. Installation of shoreline protection structures is increasing in response to rising sea levels and increasing frequency of intense storms. Shoreline hardening structures can facilitate establishment of non-native species with multiple potential consequences. We measured abundances of both native and non-native Codium, a green macroalga, on natural hard substrates (oyster reefs) and artificial substrates (bulkheads and revetments) in two estuaries and assessed the effects of each Codium species on nitrogen fixation and net N2 fluxes. Native C. decorticatum was the most abundant (86 %) Codium on oyster reefs, while exotic C. fragile dominated (99 %) artificial substrates. N2 production via denitrification was greater than nitrogen fixation for both species and the net N2 production associated with non-native C. fragile was greater than with native C. decorticatum. Comparing our results with surveys conducted in the 1940s before C. fragile had invaded, indicates that non-native Codium has outcompeted native Codium on artificial substrates, but that natural substrate provided by oyster reefs remains a refuge for native Codium. Although shoreline hardening with artificial structures can reduce ecosystem services provided by coastal marsh and other habitats, an unexpected beneficial consequence was the N2 production associated with the non-native Codium, which has the potential to mitigate anthropogenic nutrient loading. Our results illustrate that the interaction between multiple anthropogenic impacts can be positive, and indicate that non-ephemeral macroalgae could be an overlooked component in nitrogen removal from marine ecosystems by enhancing denitrification.

Bonamia exitiosa transmission among, and incidence in, Asian oyster Crassostrea ariakensis under warm euhaline conditions.

Abstract: Previously reported in Australia, New Zealand, and more recently in Europe, the protistan parasite Bonamia exitiosa was also reported in the mid-Atlantic region of the USA after causing serious mortalities there in the Asian oyster Crassostrea ariakensis. At the time, this oyster was being considered for introduction, and the potential consequences of introducing this species were being assessed using field and laboratory studies. B. exitiosa emerged as the most serious disease threat for this oyster species, especially under warm euhaline conditions and for oysters <50 mm in size. To better evaluate how quickly this parasite may be able to spread among C. ariakensis, we investigated B. exitiosa transmission and incidence in C. ariakensis. During a first trial, potential direct transmission of B. exitiosa was evaluated by cohabitating infected C. ariakensis with uninfected C. ariakensis under in vivo quarantine conditions. In a second experiment, B. exitiosa incidence was estimated in situ by determining its prevalence in C. ariakensis deployed in an enzootic area after 4, 7, 14, 21 and 28 d of exposure. Results suggest that under warm euhaline conditions B. exitiosa can be transmitted among C. ariakensis without requiring any other parasite source and that parasite incidence may be at least as high as 40% after only 4 d exposure to an enzootic area. These results underscored the severity of the bonamiasis disease threat to C. ariakensis and provided further evidence that efforts to build an aquaculture industry based on C. ariakensis in the eastern USA might have been thwarted by parasitic disease.