Effects of a tropical cyclone on salt marsh insect communities and post‐cyclone reassembly processes

Abstract

Concepts regarding effects of recurrent natural disturbances and subsequent responses of communities are central to ecology and conservation biology. Tropical cyclones constitute major disturbances producing direct effects (damage, mortality) in many coastal communities worldwide. Subsequent reassembly involves changes in composition and abundance for which the underlying mechanisms (deterministic and stochastic processes) are still not clear, especially for mobile organisms. We examined tropical cyclone-induced changes in composition and reassembly of entire insect communities in 16 Louisiana coastal salt marshes before and after Hurricane Isaac in 2012 and 2013. We used the Shannon index and multivariate permutational ANOVA to study insect resistance and resilience, β diversity partitioning to evaluate the importance of species replacement, and null models to disentangle the relative roles of different assembly processes over time after the tropical cyclone. The α diversity and species composition, overall and for different trophic levels, decreased immediately after the tropical cyclone; nonetheless, both then increased rapidly and returned to pre-cyclone states within one year. Changes in species abundance, rather than species replacement, was the primary driver, accounting for most temporal dissimilarity among insect communities. Stochastic processes, which drove community composition immediately after the tropical cyclone, decreased in importance over time. Our study indicates that rapid reformation of insect communities involved sequential landscape-level dynamics. Cyclone-resistant life cycle stages apparently survived in some, perhaps random locations within the overall salt marsh landscape. Subsequently, stochastic patterns of immigration of mobile life cycle stages resulted in rapid reformation of local communities. Post-cyclone direct regeneration of salt marsh insect communities resulted from low resistance, coupled with high landscape-level resilience via re-immigration. Our study suggests that the extent of direct regeneration of local salt marsh insect communities might change with the size of larger marsh landscapes within which they are imbedded.

Disentangling Niche Theory and Beta Diversity Change

“…This is surprising because Tanner and Bellingham (2006) suggest that one group of species with high 𝑧 𝑖𝛽 scores were "most resistant to hurricane damage"; the habitat specialists in the nutrient-poor Mor site. Beta diversity in other ecosystems disturbed by hurricanes is also mainly influenced by drift (Chen et al 2020). Tanner and Bellingham (2006) emphasized the recruitment of new species in the post-hurricane survey, but were unable to quantify its effects.…”

Disentangling niche theory and beta diversity change

“…This is surprising because Tanner and Bellingham (2006) suggest that one group of species with high scores were "most resistant to hurricaine damage"; the habitat specialists in the nutrient-poor Mor site. Beta diversity in other ecosystems disturbed by hurricanes is also mainly influenced by drift (Chen et al 2020). Tanner and Bellingham (2006) emphasized the recruitment of new species in the post-hurricane survey, but were unable to quantify its effects.…”

Community and Species-Level Changes of Insect Species Visiting Mangifera indica Flowers Following Hurricane María: “The Devil Is in the Details”

“…(2) understand the role of diversity and abundance of insect communities vs. the role of individual insect species on the reproduction of a worldwide economically important species, and how these relationships may be influenced by extreme weather events; (3) discuss how this information may inform pollinator management in crop systems in areas where catastrophic weather events such as hurricanes are frequent events. The literature related to post-hurricane dynamics in arthropod communities suggests that while arthropod populations can take different pathways (increase, decrease, or else exhibit complex responses (e.g., Gandhi et al, 2007), under some circumstances these assemblages can be highly resilient and return to pre-hurricane levels in a short period of time (Chen et al, 2020). However, this does not always occur because species responses to hurricanes can depend on the taxon, guild and the environmental context (biotic and abiotic) in which they occur (Schowalter et al, 2017;Novais et al, 2018;Savage et al, 2018).…”

“…Some responses are modulated by spatial differences in microhabitat (e.g., Schowalter et al, 2017) and others by species interactions within and between trophic levels (e.g., Schowalter, 2012;Novais et al, 2018). From the perspective of diversity changes, it has been argued that while extreme weather events (hurricanes and frosts) often result in immediate reductions of alpha diversity, insect assemblages tend to be fairly resilient returning to pre-disturbance levels within 1-5 years (Marquis et al, 2019;Chen et al, 2020). It should be noted that most studies evaluating the effects of these events on insect communities do not often include pollinators.…”