Measuring temporal turnover in ecological communities

Range migrations in response to climate change, invasive species and the emergence of novel ecosystems highlight the importance of temporal turnover in community composition as a fundamental part of global change in the Anthropocene. Temporal turnover is usually quantified using a variety of metrics initially developed to capture spatial change. However, temporal turnover is the consequence of unidirectional community dynamics resulting from processes such as population growth, colonisation and local extinction. Here, we develop a framework based on community dynamics and propose a new temporal turnover measure. A simulation study and an analysis of an estuarine fish community both clearly demonstrate that our proposed turnover measure offers additional insights relative to spatial context-based metrics. Our approach reveals whether community turnover is due to shifts in community composition or in community abundance and identifies the species and/or environmental factors that are responsible for any change

Spillover effects of a community-managed marine reserve

The value of no-take marine reserves as fisheries-management tools is controversial, particularly in high-poverty areas where human populations depend heavily on fish as a source of protein. Spillover, the net export of adult fish, is one mechanism by which no-take marine reserves may have a positive influence on adjacent fisheries. Spillover can contribute to poverty alleviation, although its effect is modulated by the number of fishermen and fishing intensity. In this study, we quantify the effects of a community-managed marine reserve in a high poverty area of Northern Mozambique. For this purpose, underwater visual censuses of reef fish were undertaken at three different times: 3 years before (2003), at the time of establishment (2006) and 6 years after the marine reserve establishment (2012). The survey locations were chosen inside, outside and on the border of the marine reserve. Benthic cover composition was quantified at the same sites in 2006 and 2012. After the reserve establishment, fish sizes were also estimated. Regression tree models show that the distance from the border and the time after reserve establishment were the variables with the strongest effect on fish abundance. The extent and direction of the spillover depends on trophic group and fish size. Poisson Generalized Linear Models show that, prior to the reserve establishment, the survey sites did not differ but, after 6 years, the abundance of all fish inside the reserve has increased and caused spillover of herbivorous fish. Spillover was detected 1km beyond the limit of the reserve for small herbivorous fishes. Six years after the establishment of a community-managed reserve, the fish assemblages have changed dramatically inside the reserve, and spillover is benefitting fish assemblages outside the reserve

Supplementary information files for Regional occupancy increases for widespread species but decreases for narrowly distributed species in metacommunity time series

Supplementary files for article Regional occupancy increases for widespread species but decreases for narrowly distributed species in metacommunity time series   While human activities are known to elicit rapid turnover in species composition through time, the properties of the species that increase or decrease their spatial occupancy underlying this turnover are less clear. Here, we used an extensive dataset of 238 metacommunity time series of multiple taxa spread across the globe to evaluate whether species that are more widespread (large-ranged species) differed in how they changed their site occupancy over the10-90 years the metacommunities were monitored relative to species that are more narrowly distributed (small-ranged species). We found that on average, large-ranged species tended to increase in occupancy through time, whereas small-ranged species tended to decrease. These relationships were stronger in marine than in terrestrial and freshwater realms. However, in terrestrial regions, the directional changes in occupancy were less extreme in protected areas. Our findings provide evidence for systematic decreases in occupancy of small-ranged species, and that habitat protection could mitigate these losses in the face of environmental change.</p

Appendix B. Comparison of alternative zero-sum multinomial fits.

Comparison of alternative zero-sum multinomial fits

Additional Analysis from Allometric growth in reef-building corals

Analysis of the robustness of morphotype classification, and of the inclusion of colony as a random facto

Appendix C. Poisson vs. hypergeometric bootstrap results.

Poisson vs. hypergeometric bootstrap results

Summary data of the multivariate regression tree constructed based on herbivorous fish abundances.

<p>We present the values for: the CVRE (Cross Validated Relative Error), the number of splitting nodes and variable prediction values for each node. D-distance, Y-years.</p><p>Summary data of the multivariate regression tree constructed based on herbivorous fish abundances.</p

Map of Vamizi Island and location in Mozambique.

<p>Locations 1, 2 and 3 outside the MR. Locations 4, 5 and 6 inside the MR.</p

A multivariate regression tree was built based on herbivorous fish abundances.

<p>For each node the mid-point value of the split is reported, and on each leaf the number of observations (n) on that leaf.</p

Nonmetric Multi Dimensional Scaling (NMDS) of the benthic observations by: A- Year of observations B- Distances to the border.

<p>(negative values outside the border, positive values inside the border)</p