Scientists tend to have differing beliefs concerning beach replenishment, usually depending on their field of expertise. In general, biologists and environmentalists are against beach replenishment, geologists are divided, and engineers are in favor of it. Information regarding each group's perspectives can be found below.
Biologists
Geologists
Engineers
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A driving force positioning fishermen against beach replenishment is the burial of marine invertebrates, particularly mole crabs. Scientists also study this occurrence with regularity. Tyler Wooldridge, Heather Henter and Joshua Kohn recently produced the most extensive study to date in the paper "Effects of beach replenishment on intertidal invertebrates: A 15-month, eight beach study". Overall, they found that invertebrate populations significantly decreased on replenished beaches. Interestingly, mole crabs actually increased in abundance, but the paper explores the mole crab's lifecycle in detail as well. Mole crabs have a pelagic stage, meaning that they live in the open ocean for a period of their life. Therefore, it was likely that the mole crab population that bloomed along a replenished beach was actually out at sea during the time of replenishment. The authors also note the likely impacts that reductions in invertebrate populations will have on coastal fish and shore-bird populations as well. Beyond the direct environmental impacts, biologists also point to a lack in quality research conducted by the ACE, particularly the overlooking of the peer review process.
Unlike biologists, who study beach replenishment effects on wildlife, or engineers, who study beach replenishment effects on people, geologists look at the actual process of conducting beach replenishment. The most important factor in producing a successful replenishment procedure is matching the imported sand's grain size to that of the beach's natural sand, according to geologists. This requires carefully selecting a dredging site, and geologists recommend making shallower cuts while dredging to minimize impacts to the dredged location. However, not all dredge sites are recycled by eroding beach sand, and the removal of all usable sand from a dredge site may act as a limiting factor in future nourishment projects. Geologists suggest conducting beach replenishment during times opposite to that of peak intertidal invertebrate recruitment as well.
Engineers tend to promote beach replenishment, using a cost benefit analysis to assess the efficiency of beach replenishment as opposed to other alternatives. Storm protection of infrastructure, rather than biological impacts on intertidal fauna, is the main concern of engineers. Most engineers believe that beach replenishment, rather than building a hardened structure or choosing not to alter a natural beach, is the most cost effective and successful method of protecting a beachfront community from storms. Cost benefit analyses take the values of potentially affected properties into account, as well as the likeliness of a storm impacting the area, to determine whether beach replenishment should be conducted.
"We found rather long lasting declines in invertebrate abundances due to replenishment" Joshua Kohn, Biology Professor at the University of California- San Diego