Alteration of Island Food-Web Dynamics Following Major Disturbance by Hurricanes

Abstract

Major abiotic disturbance can be an important factor influencing food-web dynamics, particularly in areas impacted by the recent increase in hurricane activity. We present a unique set of data on key food-web processes occurring on 10 small islands for three relatively calm years and then four subsequent years during which two hurricanes passed directly over the study site. Herbivory, as measured by leaf damage, was 3.2 times higher in the year after the first hurricane (2000) than in the previous year and was 1.7 times higher in the year after the second hurricane (2002) than in 2001. The effect of a top predator (the lizard, Anolis sagrei) on herbivory strengthened continuously after the first hurricane and overall was 2.4 times stronger during the disturbance period than before. Overall abundance of lizards was 30% lower during the disturbance period than before, and abundances of web spiders and hymenopteran parasitoids were 66% and 59% lower, respectively. We suggest that increased herbivory observed on all islands was caused, at least in part, by the overall reduction in predation by both lizards and arthropods, whereas magnification of the lizard effect on herbivory was caused by reduced compensatory predation by arthropods.

Climatic control of trophic interaction strength: the effect of lizards on spiders

“…Previously, we showed that herbivory increased markedly in Abaco following hurricane disturbance and suggested that this was caused by a reduction of many predatory species, including lizards, spiders and parasitoids (Spiller and Schoener 2007). Hence, hurricane disturbance associated with extremely high rainfall may devastate predators in multiple trophic levels simultaneously and thereby decrease the overall trophic interaction strength of predators on herbivores, as in the descending portion of Fig.…”

“…In 1999, the year with highest June-November rainfall, Floyd (a category IV hurricane) passed directly over the study site in September and the storm surge completely inundated all the study islands; all free-living lizards apparently died or were washed away (Schoener et al 2001). The islands were "repopulated" by hatchlings emerging from eggs that survived the storm surge, but lizard densities in the following spring were still much lower than before the hurricane (Spiller and Schoener 2007). In 2001, the second highest rainfall year, the surge from Michelle again completely or largely inundated the study islands and lizard densities declined (Schoener et al 2004;Spiller and Schoener 2007).…”

“…The islands were "repopulated" by hatchlings emerging from eggs that survived the storm surge, but lizard densities in the following spring were still much lower than before the hurricane (Spiller and Schoener 2007). In 2001, the second highest rainfall year, the surge from Michelle again completely or largely inundated the study islands and lizard densities declined (Schoener et al 2004;Spiller and Schoener 2007). The link between years with high rainfall and high tropical storm activity is caused by forces from both the Atlantic and PaciWc Oceans that create climatological conditions in the Caribbean simultaneously promoting higher rainfall and greater tropical storm formation (Bove et al 1998;Taylor et al 2002;C.…”

“…1. Since that study tropical storm activity has increased markedly in the Atlantic Basin (Goldenberg et al 2001), and we have documented the impact of major hurricanes on island food webs in two areas in the Bahamas Schoener et al 2001;Spiller and Agrawal 2003;Spiller and Schoener 2007). One of the areas, Abaco, was directly hit by Hurricane Floyd (category IV) in 1999, the Wrst major hurricane to strike that area since 1965 (UNISYS.COM 2004).…”

How do beetle assemblages respond to cyclonic disturbance of a fragmented tropical rainforest landscape?

“…However, in contrast to the outbreak of insect herbivores following Hurricane Hugo (Torres 1992), we found that changes in the abundance of chrysomelids (herbivorous beetles) were not correlated with the general increase in the amount of foliage near the ground. Both increases and decreases in the abundance of herbivorous insects post-cyclone have been observed (Schowalter and Ganio 1999;Barberena-Arias and Aide 2002;Angulo-Sandoval et al 2004) and the reasons for inconsistent results may be related to predator control (Spiller and Schoener 2007).…”