Reciprocal facilitation between annual plants and burrowing crabs:Implications for the restoration of degraded saltmarshes

Increasing evidence shows that facilitative interactions between species play an essential role in coastal wetland ecosystems. However, there is a lack of understanding of how such interactions can be used for restoration purposes in saltmarsh ecosystems. We therefore studied the mechanisms of reciprocal facilitative interactions between native annual plants, Suaeda salsa, and burrowing crabs, Helice tientsinensis, in a middle-elevation saltmarsh (with generally high plant density and moderate tides) in the Yellow River Delta of China. We investigated the relationship between the densities of the plants and crab burrows in different seasons. Then, we tested whether and how saltmarsh plants and crabs indeed facilitate each other in a series of field and laboratory experiments. Finally, we applied the results by creating a field-scale artificial approach for microtopographic modification to restore a degraded saltmarsh. We found that the density of plant seedlings in spring was positively correlated with the density of crab burrows in the previous autumn; moreover, the density of crab burrows was correlated with the density of plants in summer. The concave-convex surface microtopography created by crabs promoted seed retention and seedling establishment of saltmarsh plants in winter and spring. These plants in turn facilitated crabs by inhibiting predators, providing food and reducing physical stresses for crabs in summer and autumn. The experimental removal of saltmarsh plants decreased crab burrow density, while both transplanting and simulating plants in bare patches promoted crabs. The microtopographic modification, inspired by our new understanding of the interactions between saltmarsh plants and crabs, showed that these degraded saltmarsh ecosystems can be restored by a single ploughing intervention. Synthesis. Our results suggest a reciprocal facilitation between annual plants and burrowing crabs in a middle-elevation saltmarsh ecosystem. This knowledge yielded new restoration options for degraded coastal saltmarshes through the one-time ploughing initiation of microtopographic variation, which could promote the re-establishment of ecosystem engineers and lead to the efficient recovery of pioneer coastal vegetation and associated fauna

Largest GWAS of PTSD (N=20 070) yields genetic overlap with schizophrenia and sex differences in heritability.

The Psychiatric Genomics Consortium-Posttraumatic Stress Disorder group (PGC-PTSD) combined genome-wide case-control molecular genetic data across 11 multiethnic studies to quantify PTSD heritability, to examine potential shared genetic risk with schizophrenia, bipolar disorder, and major depressive disorder and to identify risk loci for PTSD. Examining 20 730 individuals, we report a molecular genetics-based heritability estimate (

GIS Data for: Cross-boundary human impacts compromise the Serengeti-Mara ecosystem

Available spatial datasets: Chapter 3: - GSME SRTM 3 500m Focal Statistics Mean Hillshade (data from SRTM-3) - GSME CHIRPS Mean Annual Rainfall - calculated from CHIRPS data over the period 2001-2017 (Climate Hazards Group, Santa Barbara; analysis: Michiel Veldhuis) - GSME Main Rivers - GSME lakes Chapter 6: - Land use data - Landsat 5 TM, 7 ETM+ (slc-on) and 8 (period 1984 - 2018; analysis: Anna Estes) Chapter 7 (data from Google Earth Pro; analysis: Michiel Veldhuis): - GSME Protected Areas Boundaries - GSME Bomas 2016 - GSME_vectordata - Livestock Paths 2016 Chapter 8 & 9: - GSME_data_v1 - Main Rivers - GSME_vectordata - Livestock Paths 2016 - GSME Bomas 2016 - GSME Protected Areas Boundaries - GSME Last burned 2001 to 2016 - compiled from Moderate-resolution Imaging Spectroradiometer data (MODIS MCD64 V6); analysis: Michiel Veldhuis - GSME sentinel2 RGB 201612 Chapter 10: - GSME_data_v1 - Main Rivers - GSME_vectordata - Livestock Paths 2016 - GSME Bomas 2016 - GSME Protected Areas Boundaries - wildebeest_occupancy_change1999_2007_vs_2008_2017 - Change in wildebeest utilization between the periods 1999-2007 and 2008-2017 from radio collared individuals (data credit Grant C. Hopcraft and Thomas Morrison, University of Glasgow

Appendix A. Figures showing the influence of the short-grass context of treatment plots on plot selection by four savanna grazers using windows with lengths ranging from 3 to 19 m.

Figures showing the influence of the short-grass context of treatment plots on plot selection by four savanna grazers using windows with lengths ranging from 3 to 19 m

GIS Data for: Cross-boundary human impacts compromise the Serengeti-Mara ecosystem

Available spatial datasets: Chapter 3: - GSME SRTM 3 500m Focal Statistics Mean Hillshade (data from SRTM-3) - GSME CHIRPS Mean Annual Rainfall - calculated from CHIRPS data over the period 2001-2017 (Climate Hazards Group, Santa Barbara; analysis: Michiel Veldhuis) - GSME Main Rivers - GSME lakes Chapter 6: - Land use data - Landsat 5 TM, 7 ETM+ (slc-on) and 8 (period 1984 - 2018; analysis: Anna Estes) Chapter 7 (data from Google Earth Pro; analysis: Michiel Veldhuis): - GSME Protected Areas Boundaries - GSME Bomas 2016 - GSME_vectordata - Livestock Paths 2016 Chapter 8 & 9: - GSME_data_v1 - Main Rivers - GSME_vectordata - Livestock Paths 2016 - GSME Bomas 2016 - GSME Protected Areas Boundaries - GSME Last burned 2001 to 2016 - compiled from Moderate-resolution Imaging Spectroradiometer data (MODIS MCD64 V6); analysis: Michiel Veldhuis - GSME sentinel2 RGB 201612 Chapter 10: - GSME_data_v1 - Main Rivers - GSME_vectordata - Livestock Paths 2016 - GSME Bomas 2016 - GSME Protected Areas Boundaries - wildebeest_occupancy_change1999_2007_vs_2008_2017 - Change in wildebeest utilization between the periods 1999-2007 and 2008-2017 from radio collared individuals (data credit Grant C. Hopcraft and Thomas Morrison, University of Glasgow