Echyridella menziesii (Bivalvia: Hyriidae) as a predator of zooplankton of different sizes; are large non-indigenous Daphnia a potential food source?     

Anita A. C. Pearson 《新西兰海洋与淡水研究杂志》2019,53(3):327-337

Interactions between two recent invaders to New Zealand, the cladocerans Daphnia galeata and D. pulex, and native filter-feeding freshwater mussels, are unknown. We examined predation rates of the common native mussel Echyridella menziesii (kākahi, kāeo) on non-native Daphnia (comparatively large zooplankton in New Zealand), relative to two common native species, the smaller cladoceran Bosmina meridionalis and rotifer Brachionus calyciflorus. Controlled laboratory experiments were conducted in which each zooplankton species was exposed to bivalve predation for a two-hour period. Comparing treatments to non-mussel controls, removal rates of non-indigenous D. pulex and native B. calyciflorus were statistically significant. Nevertheless, kākahi removal rates may not be ecologically significant for daphnids (1.7% D. galeata and 7.4% D. pulex). Kākahi removed 8.8% of B. meridionalis and 30.2% of B. calyciflorus, suggesting that small, feeble zooplankton species (particularly rotifers) are most susceptible to predation, and potentially function as an energy source for native freshwater mussels.  相似文献   

Framing up the “Stretching” of Co-Management     

Leonie J. Pearson  Melanie Dare 《社会与自然资源》2019,32(4):363-381

Collaborative management, or co-management, is recognized as best practice for protected area management. A vast literature explores the benefits and challenges of implementing co-management, but more literature is not always better. We propose that the term co-management has been uncritically “stretched”, losing its original framing of actors working together collaboratively. Co-management has become a facade under which traditional hierarchical and market-based management regimes can occur. Conceptual stretching inhibits the capacity to critically articulate variations within models of collaborative governance. We investigate this stretching through a nuanced framework of co-management models with varying intensities. By considering participating actors, institutions and delivery objectives, the theoretically informed and empirically tested framework highlights the stretched implementation of co-management, enabling protected area managers an opportunity to align their practice with the promise of co-management.  相似文献   

Overtopping performance of different armour units for rubble mound breakwaters     

T. Bruce  J.W. van der Meer  L. Franco  J.M. Pearson 《Coastal Engineering》2009

This paper describes a major programme of small-scale physical model tests to establish better the influence of armour type and configuration on overtopping. Specifically, 179 tests determined the relative difference in overtopping behaviour for 13 types/configurations of armour. Roughness factors γ_f were determined for rock (two layers), cubes (single layer and two layers), Tetrapod, Antifer, Haro, Accropode, Core-Loc™ and Xbloc™. These roughness influence factors have been included in the CLASH database and are for use in the neural network prediction of overtopping. Individual wave-by-wave overtopping volumes were analysed and found to compare well with current prediction methods. Measured reflection coefficients for the different units are also presented and compared with recent formulae.  相似文献   

Dating the course of the lower red river in Louisiana: The archaeological evidence     

Charles E. Pearson 《Geoarchaeology》1986,1(1):39-43

Archaeological data from the lower Red River in Louisiana indicate that the modern course of the river is 1200 years older than previously suggested. Geologists claim a diversion of Red River through Moncla Gap approximately 500 to 1000 years ago. Marksville period occupations dating prior to A.D. 200 are identified at archaeological sites adjacent to the river below Moncla Gap. The position of these sites on Red River levees demonstrate that they post-date the river's occupancy of the area. Extensive Marksville and later prehistoric occupations in the Moncla Gap area are seen as a direct result of the development of riverine environments resulting from this diversion.  相似文献