Pollinator communities important to agriculture in the Bay of Fundy dykelands of Nova Scotia

Abstract

In the Bay of Fundy dykelands, efforts are underway to determine the trade-offs of ecosystem services between maintaining man-made dykes and restoring them back to the salt marsh habitat that existed in their place prior to European colonization. Dykes protect agricultural land but are at risk due to sea level rise, and there is a lack of resources to keep them functioning. Salt marsh restoration is being proposed due to their ability to protect coastlines while also providing other benefits such as carbon storage, but prior to this it must be known what impacts restoration could have on other ecosystem services. Pollination is one such service, and I assessed pollinator importance to agriculture and the community composition of the wild pollinators providing this service. To determine pollinator importance to crops, I excluded flowers of apple, tomato, and squash from pollination using mesh bags and compared them to those in which pollination was permitted. I found that pollinators increase both fruit set and weight in apple and tomato, but was unable to get conclusive results in squash. Apple was completely reliant on pollinators for successful fruit production, with tomato benefitting from pollination to a lesser, but still significant, degree. Sweep net and bowl-trapping surveys were conducted to determine the species that visited these crops, and I found that wild ground-nesting bees were the most important pollinators of all crops (72% of all bees collected), being found in higher abundances than even domesticated honey bees. Notably, many of these bee species were also detected in a past study in dyke and salt marsh habitats, with <i>Agapostemon virescens</i> and <i>Lasioglossum leucozonium</i> being amongst the most abundant species. Given the importance of wild pollinators found in this study, pollinator conservation measures should be undertaken within agroecosystems to ensure the continued delivery of this ecosystem service to farmers, while allowing for salt marsh restoration on a case-by-case basis.