The role of microphytobenthos in soft‐sediment ecological networks and their contribution to the delivery of multiple ecosystem services

Abstract

1. Sediment dwelling, microscopic primary producers, that occupy sediments in the photic zone, are commonly referred to as microphytobenthos (MPB). The MPB are essential components of soft-sediment systems, but are often overlooked when assessing coastal ecosystem functionality and service delivery. 2. The MPB are involved in several complex interactions and feedback that underpin the delivery of vital ecosystem services. MPB profoundly influence the flow and cycling of carbon and nutrients, such as nitrogen, directly and indirectly underpinning highly productive shallow water marine food webs. The MPB can also stabilize sediments through the formation of biofilms, and significantly improve water quality by mediating the benthic-pelagic coupling of nutrients, sediment and pollutants. 3. The functional role of the MPB is compromised by increasing anthropogenic pressures such as nutrient enrichment, sedimentation, herbicides and emerging contaminants such as microplastic pollution. However, MPB are extremely good at buffering the effects of these land-sourced stressors at the interface between land and sea. 4. Synthesis. Society often appreciates the final provisioning of goods and services from our coastal marine environments. However, provisioning services are only possible due to the multitude of supporting and regulating services that underpin them. Microphytobenthos (MPB) are central to benthic ecological networks, and contribute to ecosystem service delivery through various pathways. Understanding the critical role of MPB in complex networks is therefore essential to appreciate their importance in ecosystem function and service delivery into the future. K E Y W O R D S benthic microalgae, ecosystem services, estuarine systems, microphytobenthos, service delivery, soft-sediment ecology 816 | Journal of Ecology HOPE Et al.

Water Column Turbidity Not Sediment Nutrient Enrichment Moderates Microphytobenthic Primary Production

“…This ultimately can have substantial implications for coastal ecosystems through indirectly facilitating the removal of nutrients in oligotrophic systems or contributing to accelerating water column primary production in eutrophic systems. Consequently, reduced MPB productivity during submergence not only has direct implications on the supply of labile carbon and therefore coastal food webs [6] but can cascade onto reductions in the capacity to moderate pollutants, changes in trophic structure and alterations in nutrient cycling and transformation pathways [10,63,64]. In combination, these changes feedback within the system to modify ecological interaction networks and push ecosystems closer towards tipping points [65][66][67].…”

“…Microphytobenthos (MPB) are often the dominant primary producer in shallow temperate ecosystems, accounting for up to 50% of total estuarine autochthonous primary production and up to 80% of total benthic carbon fixation [9]. While MPB productivity can supply high-quality labile carbon, and thus underpin coastal food webs [6], MPB also modify sediment stability and, through oxygenation of the sediment and nutrient uptake, alter biogeochemical pathways including nutrient recycling [8,10,11]. MPB are therefore fundamental constituents of intertidal habitats, with reductions in productivity likely to have cascading implications for entire coastal ecosystems.…”

Microscale Variability in Biomass and Photosynthetic Activity of Microphytobenthos During a Spring-Neap Tidal Cycle

“…Benthic microalgal communities are important ecological players on intertidal estuarine sediments. They can be responsible for a significant fraction of the total estuarine primary production Underwood and Kromkamp, 1999;Christianen et al, 2017), providing a range of ecosystem services (Hope et al, 2019), such as provision of a highly nutritious food source that can be used directly or indirectly by higher trophic levels including important wading bird populations (Kuwae et al, 2008). Microphytobenthos (MPB) can also be considered important ecosystem engineers as the presence of surface biofilms gives enhanced resistance against erosion (Paterson, 1989;Paterson and Black, 1999;Decho, 2000;Underwood and Paterson, 2003).…”

Effect of Nutrient Enrichment and Turbidity on Interactions Between Microphytobenthos and a Key Bivalve: Implications for Higher Trophic Levels

“…Intertidal MPB underpin multiple ecosystem functions and services (Hope et al, 2019). These photosynthetic organisms are the sole source for omega-3 and omega-6 essential fatty acids (EFA) to higher trophic levels and the synthesis of these essential nutrients can be affected by light and nutrient conditions (Hill et al, 2011).…”