Habitat preferences of macroinvertebrate fauna among seagrasses with varying structural forms

Abstract

The role of habitat structural complexity in shaping faunal communities has been of key interest to marine ecologists for many years, principally due to the association between increased complexity and high abundances and diversity of fauna. Despite this, macroinvertebrate assemblages within seagrasses with varying morphologies and canopy structures have seldom been compared. Algal epiphytes also contribute to the structural complexity of seagrass ecosystems, a factor often overlooked in studies on seagrass structural complexity. We used artificial seagrass units (ASUs) with varying structure to determine the relative importance of food versus structure for macroinvertebrate fauna (Experiment 1). We also tested whether the importance of different structural components of seagrasses for macroinvertebrate fauna was consistent between seagrasses (Amphibolis griffithii, Posidonia sinuosa and Cymodocea nodosa) with naturally different complexity (Experiment 2). In Experiment 1, the treatments with the combination of food and structure together had the greater density of colonizing macroinvertebrates, compared to those where either structure or food were independently tested. In Experiment 2, the density of fauna colonizing ASUs varied among complexities of ASUs, as well as seagrasses. When ASU\u27s were placed alongside A. griffithii and P. sinuosa (species which vary greatly in morphology, but little in available surface area) the highest densities of fauna were generally found on ASUs with artificial epiphytes. This suggests that small-scale variation in structure was more important than large-scale variation in canopy morphology. However, there was no difference in the total density of fauna colonizing onto ASUs placed alongside C. nodosa, which morphologically has a structure similar to P. sinuosa, but much lower surface area. We conclude from these experiments that the effect of high structural complexity in seagrasses is an important driver of macroinvertebrate density, in particular, that provided by algal epiphytes. However, the effect of structural complexity may be reduced when seagrass canopy surface area is limited

Comparison of epifaunal assemblages betweenCymodocea nodosaandCaulerpa proliferameadows in Gran Canaria (eastern Atlantic)

“…Meadows constituted by C. nodosa are the dominant vegetated communities on shallow soft substrates throughout the Canary Islands (Pavón-Salas et al, 2000;Barberá et al, 2005;Monterroso et al, 2012), where they provide food and shelter for diverse invertebrate and fish assemblages, including a 'nursery' habitat for larval and juvenile fish stages (Tuya et al, 2006;Espino et al, 2011aEspino et al, , 2011b. However, C. nodosa meadows are severely decreasing at local scales, as a result of a range of humanmediated impacts (Martínez-Samper, 2011;Tuya et al, 2013). In these coastal areas, the decline of C. nodosa seagrass meadows often results in the replacement by opportunistic green algae of the genus Caulerpa, Caulerpa prolifera (Forsskål) J.V.…”

Large-Scale Prediction of Seagrass Distribution Integrating Landscape Metrics and Environmental Factors: The Case of Cymodocea nodosa (Mediterranean–Atlantic)

“…There, populations have also been reported to be affected by biotic interactions , or population bottlenecks (Cunha et al 2013). C. nodosa develops ecologically important meadows providing a favorable habitat for fishes and invertebrates (e.g., Espino et al 2011;Gartner et al 2013;Guidetti and Bussotti 2000;Tuya et al 2014a), or stabilizing sediments (Cabaço et al 2010). Due to its importance, C. nodosa is listed for protection by the OSPAR (http://www.…”

Photo-physiological performance and short-term acclimation of two coexisting macrophytes (<em>Cymodocea nodosa</em> and <em>Caulerpa prolifera</em>) with depth

“…Meadows constituted by C. nodosa are found on shallow sandy substrates throughout the Canary Islands (Barberá et al 2005), supporting diverse invertebrate and fish assemblages (Tuya et al 2006, Gardner et al 2013, Tuya et al 2013b. Across its distribution range, declines in the presence of C. nodosa may result in increases in the biomass of green algae, particularly those of the genus Caulerpa, including native (Lloret et al 2005, García-Sánchez et al 2012) and non-native species (Ceccherelli and Cinelli 1997).…”