. The ecological impact of beach nourishment with dredged materials on the intertidal zone at Bogue Banks, North Carolina. Beach erosion; Dredging; Ecology. The first appearance of the three portunid crabs appeared to be linked to water temperatures rising above 16° Celsius; however, the numbers varied widely throughout the year (Fig. 17). The cause of this variation was not clear. Certainly some variation was related to difficult collecting conditions (in turbid waters the crabs are difficult to see), but steepness of the beach slope, grain size, food availability, predation, and current velo
. The ecological impact of beach nourishment with dredged materials on the intertidal zone at Bogue Banks, North Carolina. Beach erosion; Dredging; Ecology. The first appearance of the three portunid crabs appeared to be linked to water temperatures rising above 16° Celsius; however, the numbers varied widely throughout the year (Fig. 17). The cause of this variation was not clear. Certainly some variation was related to difficult collecting conditions (in turbid waters the crabs are difficult to see), but steepness of the beach slope, grain size, food availability, predation, and current velocity are also possible controlling factors. 50 40 £»- 30 20 10 iiiiiiii Nourishment t Period Uw£. F M A S O Month NDJ FMAMJ iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiigiiii J A Figure 17. Densities of A. cribrarius, 0. oaellatus, and 0. quadrata in the surf zone at Fort Macon, January 1977 to August 1978. The slashed line below the X-axis represents the actual duration of the nourishment. Regardless of what factors normally control the densities of these three species of surf zone consumers (0. ooellatus^ A. ovibvarius, and C. sapidus), the nourishment at Fort Macon severely reduced their abundance. Collections during nourishment were more difficult due to increased turbidity and greater beach slope and could have prevented detection of some crabs. However, poor collecting conditions are not believed to fully explain the low numbers observed because, even after nourishment had ceased and collecting conditions had improved, the number of crabs present remained markedly lower compared to den- sities recorded before nourishment. Several explanations for the reduced numbers of crabs in the surf zone are possible: 31. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Reilly, Francis J; Bellis, Vincent J. , 1938-;
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Photo credit: © The Book Worm / Alamy / Afripics
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectecology
