New habitats created by non-native mangroves could inform future management of some invasive species – ScienceDaily
In a new article published in the Journal of Applied Ecology, Elise Granek, professor of environmental and management sciences, and lead author Casey Lewis, former PSU student, report the results of a census of zooplankton communities in non-native mangrove habitats and open coastline on the island of Moloka’i, Hawaii. The study found that the diversity of zooplankton communities in the mangrove stands was comparable to that of the open coast. In addition, the authors report that although they found that some species were less abundant in mangrove sites, other rare species were only present in mangrove habitats. The results suggest that non-native mangroves may benefit rather than hamper zooplankton, many of which are important species in the ecosystems they inhabit.
The implications of the document suggest that in the face of declining fisheries, threatened reef ecosystems, and changing climatic and ocean conditions, the value of ecosystem services provided by some invasive species, for example mangroves, may outweigh their negative effects. Therefore, the decision-making process involved in the management of some invasive species warrants a closer examination of the costs and benefits provided to the ecosystem.
“In a static world, invasive species are bad because they disrupt ecosystems,” Granek said. “But we live in a world where the environment is changing. The climate is changing. Oceans are changing. It changes the calculation of the severity of certain invasive species for the habitats they have been introduced into.”
Granek is a marine ecologist and manages the Applied Coastal Ecology Laboratory at Portland State University. Granek’s lab studies how coastal processes are affected by disturbances such as invasive species and pollutants.
Mangroves, native to subtropical and tropical latitudes, were introduced to Moloka’i in the early 20th century to control soil erosion. Over the past 100 years, trees have created new ecosystems on parts of the island’s coast and have spread to other Hawaiian islands. Granek’s thesis work focused on the ecology of the mangrove in the tree’s natural habitat and revealed that mangroves supported a rich biodiversity of zooplankton in the tree’s regions of origin. Zooplankton biodiversity suffered where the trees had been felled. This new study questioned whether this would be the case when humans introduce populations of mangroves. The findings of the new study suggest that the establishment of new mangrove ecosystems on Moloka’i is not of concern to local zooplankton communities and may instead provide suitable habitat for several rare species.
“I hope the results of the study will inform the conversation and highlight the need for an unbiased approach when identifying an appropriate management strategy for non-native species,” said Granek. “There is a mindset that all non-native species are harmful. It is important that we as scientists are objective and take a close look at what science says about the costs and benefits provided by non-native species. “
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