Managing coastal ecosystems and preserving socio-ecological functioning require a comprehensive understanding of ecological services provided by resident organisms. Here, we provide novel information on water-filtration activities of endobenthic sandprawns (Callichirus kraussi), which are key ecosystem engineers in South African coasts. We demonstrate experimentally that benthic engineering by sandprawns reduces phytoplankton biomass by roughly 50%. Using long-term estuarine data, we demonstrate similar reductions in phytoplankton biomass (by roughly 70%) in sandprawndominated areas. Increased burrow wall chlorophyll-a relative to surface sediments that was evident in experiments suggests that pelagic filtration occurs through bi-directional water pumping and phytoplankton adsorption onto burrow walls. Our findings expand understanding of the ecological relevance of sandprawns and functionally similar organisms, the mechanisms by which they engineer ecosystems and their role in mediating coastal bentho-pelagic coupling. Our findings also highlight the potential for deposit-feeders to be used as nature-based solutions to counter coastal eutrophication. Coastal ecosystems are some of the most productive and ecologically significant habitats on earth 1-3. They are critical nursery and feeding grounds for resident and migrant species and subsidise offshore ecosystems through nutrient and trophic transfers 4,5. Coastal ecosystems also supply valuable goods and services that support human livelihoods and local economies 2,6. However, due to their proximity to human settlements and their aesthetic appeal, coastal systems rank amongst the most threatened and degraded ecosystems on earth, owing to multiple human stressors being applied simultaneously 6-10. Nutrient enrichment is arguably the most pervasive driver of coastal deterioration in the 21 st century, resulting in notable impairments of ecosystem multi-functionality and declines in the quality of goods and services provided 11,12. Government and management agencies therefore invest heavily in measures to counter socio-ecological losses arising from excessive nutrient inputs. The harnessing of ecological functions and services provided by biological systems to overcome environmental degradation, variously referred to as ecological engineering, nature-based solutions, bioremediation and/ or biomanipulation, is increasing in popularity as a sustainable, nature-based tool that can mitigate nutrient enrichment in coastal ecosystems 12-15. In this regard, suspension-feeding organisms (e.g. clams and mussels) and coastal vegetation have dominated mitigation narratives, leading to significant investments in conservation, restoration and engineering programs that exploit their water-purification capabilities 12,16,17. In contrast, burrowing deposit-feeding organisms have been overlooked, despite them being dominant components of sedimentary biotopes (numerically and ecologically) 18-20 , which are significant constituents of coastal ecosystems. In particular, there has bee...
“Islands of fertility” result from the focussing of water and nutrients around many shrub or tree species due to plants foraging for resources. Plant–animal feedbacks may amplify the development of such islands through environmental modification due to, for example, faunal deposition of nutrients and seeds. Fauna residing within vegetation clumps are likely to exert stronger feedbacks on their hosts than itinerant species. We studied the interaction between camel thorn trees ( Vachellia erioloba ) and the colonial nests of sociable weavers ( Philetairus socius ) in the Kalahari. We hypothesized that the accumulation of biological material below the nests will alter the nutrient status of the soil beneath the nest trees, in relation to unoccupied trees and the surrounding grassland. We also suggested that this association will have both positive and negative effects on the camel thorn trees. We found that soil concentrations of N, P, and K were, respectively, 4, 4.6, and 1.2 times higher below trees with nests compared to control trees, indicating faunal concentration of nutrients. Soil δ 15 N values were higher below trees with nests than below control trees without nests. Foliar δ 15 N values were also higher in nest trees than in control trees, showing the trees accessed faunally derived N. Furthermore, foliar biomass per diameter of terminal branches was 27% higher in nest trees, suggesting that trees respond to nutrient input from the weavers with increased growth. Large barren areas in the subcanopy vegetation directly beneath the colonies were attributed to decreased water infiltration rates, as a result of accumulation of organic matter due to continuous deposition of feces, possibly limiting competitive species from establishing in the subcanopy. On the other hand, canopy volume was reduced in trees with nests due to nests occupying large volumes within the canopy, and nests frequently causing branch fall, indicating costs associated with hosting weaver colonies. Synthesis: We found nutritional benefits to camel thorn trees when hosting sociable weaver colonies. These benefits can potentially overcome important environmental constraints, but these are partially offset by the resulting costs to the host trees.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.