Temporal stability of Orbicella annularis symbioses: a case study in The Bahamas
Kennedy, E.V. ; Tonk, Linda ; Foster, N.L. ; Mumby, P.J. ; Stevens, J.R. - \ 2019
Bulletin of Marine Science 95 (2019)2. - ISSN 0007-4977 - p. 289 - 304.
Orbicella annularis (Ellis and Solander, 1786), a key reef building species, is unusual among Caribbean corals in the flexibility it displays in its symbioses with dinoflagellates in the family Symbiodiniaceae. This variability has been documented at a range of spatial scales; from within and between colonies to scales spanning the entire species range. However, temporal variability in Symbiodiniaceae communities found within O. annularis colonies is not well understood. Evidence suggests that symbiont communities in this coral species fluctuate temporally in response to environmental stressors (sporadic changes in abundance and in community composition). In this study, we investigated temporal stability of symbiont communities in O. annularis at four sites in The Bahamas over a period spanning 6 yrs. While the dominant symbiont species, Breviolum minutum (LaJeunesse et al.) J.E.Parkinson & LaJeunesse (formerly ITS2-type B1), remained stable across four patch-reef study sites, finer resolution molecular techniques revealed inter-annual variability in the presence/ absence of cryptic species Durusdinium trenchii (LaJeunesse) LaJeunesse (formerly ITS2-type D1a). Durusdinium trenchii is known to play a role in resistance to environmental stress and may have a protective effect under warm conditions. These results suggest that, while it might take an extreme environmental perturbation to trigger a long-term shift in the dominant symbiont, at background levels, less prevalent symbiont taxa are likely to be continually shuffling their relative abundances as they change in response to seasonal or environmental changes.
Seagrass ecosystem trajectory depends on the relative timescales of resistance, recovery and disturbance
O'Brien, Katherine R. ; Waycott, Michelle ; Maxwell, Paul ; Kendrick, Gary A. ; Udy, James W. ; Ferguson, Angus J.P. ; Kilminster, Kieryn ; Scanes, Peter ; McKenzie, Len J. ; McMahon, Kathryn ; Adams, Matthew P. ; Samper-Villarreal, Jimena ; Collier, Catherine ; Lyons, Mitchell ; Mumby, Peter J. ; Radke, Lynda ; Christianen, Marjolijn J.A. ; Dennison, William C. - \ 2018
Marine Pollution Bulletin 134 (2018). - ISSN 0025-326X - p. 166 - 176.
Colonizing - Opportunistic - Persistent - Recovery - Resilience - Resistance - Seagrass - Trajectory
Seagrass ecosystems are inherently dynamic, responding to environmental change across a range of scales. Habitat requirements of seagrass are well defined, but less is known about their ability to resist disturbance. Specific means of recovery after loss are particularly difficult to quantify. Here we assess the resistance and recovery capacity of 12 seagrass genera. We document four classic trajectories of degradation and recovery for seagrass ecosystems, illustrated with examples from around the world. Recovery can be rapid once conditions improve, but seagrass absence at landscape scales may persist for many decades, perpetuated by feedbacks and/or lack of seed or plant propagules to initiate recovery. It can be difficult to distinguish between slow recovery, recalcitrant degradation, and the need for a window of opportunity to trigger recovery. We propose a framework synthesizing how the spatial and temporal scales of both disturbance and seagrass response affect ecosystem trajectory and hence resilience.
Reef flattening effects on total richness and species responses in the Caribbean
Newman, Steven P. ; Meesters, E.H. ; Dryden, Charlie S. ; Williams, Stacey M. ; Sanchez, Cristina ; Mumby, Peter J. ; Polunin, Nicholas V.C. - \ 2015
Journal of Animal Ecology 84 (2015)6. - ISSN 0021-8790 - p. 1678 - 1689.
Biodiversity - Conservation - Degradation - Relief - Topography
There has been ongoing flattening of Caribbean coral reefs with the loss of habitat having severe implications for these systems. Complexity and its structural components are important to fish species richness and community composition, but little is known about its role for other taxa or species-specific responses. This study reveals the importance of reef habitat complexity and structural components to different taxa of macrofauna, total species richness, and individual coral and fish species in the Caribbean. Species presence and richness of different taxa were visually quantified in one hundred 25-m2 plots in three marine reserves in the Caribbean. Sampling was evenly distributed across five levels of visually estimated reef complexity, with five structural components also recorded: the number of corals, number of large corals, slope angle, maximum sponge and maximum octocoral height. Taking advantage of natural heterogeneity in structural complexity within a particular coral reef habitat (Orbicella reefs) and discrete environmental envelope, thus minimizing other sources of variability, the relative importance of reef complexity and structural components was quantified for different taxa and individual fish and coral species on Caribbean coral reefs using boosted regression trees (BRTs). Boosted regression tree models performed very well when explaining variability in total (82·3%), coral (80·6%) and fish species richness (77·3%), for which the greatest declines in richness occurred below intermediate reef complexity levels. Complexity accounted for very little of the variability in octocorals, sponges, arthropods, annelids or anemones. BRTs revealed species-specific variability and importance for reef complexity and structural components. Coral and fish species occupancy generally declined at low complexity levels, with the exception of two coral species (Pseudodiploria strigosa and Porites divaricata) and four fish species (Halichoeres bivittatus, H. maculipinna, Malacoctenus triangulatus and Stegastes partitus) more common at lower reef complexity levels. A significant interaction between country and reef complexity revealed a non-additive decline in species richness in areas of low complexity and the reserve in Puerto Rico. Flattening of Caribbean coral reefs will result in substantial species losses, with few winners. Individual structural components have considerable value to different species, and their loss may have profound impacts on population responses of coral and fish due to identity effects of key species, which underpin population richness and resilience and may affect essential ecosystem processes and services.