The effect of fishing on hysteresis in Caribbean coral reefs

Coral resilience is important for withstanding ecological disturbances as well as anthropogenic changes to the environment. However, the last several decades have demonstrated a decline in resilience that has often resulted in phase shifts to a degraded coral-depleted state with high levels of algal abundance. A major defining issue in current research is to identify when and how it is possible to reverse these phase shifts allowing for the ecosystem to escape coral depletion and maintain coral-based ecosystem services. We extend an analytic model to focus on the effects of over-harvesting of herbivorous reef fish in the Caribbean by explicitly including grazer dynamics which introduces feedbacks between habitat and grazer abundance posing constraints on management options excluded in previous studies. This allows us to develop ecosystem-based management recommendations for two distinct scenarios of coral reef recovery: The first follows significant habitat damage in response to a large disturbance and the second maintains reef structure but has suffered from events such as coral bleaching. We identify critical fishing effort levels to allow for coral recovery and demonstrate that regions exhibiting severe damage to reef structure have little resilience implying that fishing reductions should be coupled with other restoration methods. Regions that are coral-depleted but maintain reef structure allow for recovery given sufficiently small levels of fishing mortality. However, we demonstrate the difference in recovery time in response to varying levels of control efforts on fishing.     

Composition and phenology of Chironomidae from the Nelson Environmental Study Area,University of Kansas

The Nelson Environmental Study Area (NESA) is maintained by the University of Kansas for experimental research in ecology. Since 1983, benthic and emergent aquatic macroinvertebrates have been collected as part of several research projects. In this paper, we present the taxonomic composition and emergence phenologies of Chironomidae collected at NESA. Emergence traps, artificial substrate samplers, light traps and hand-picked specimens from D-nets yielded a total of 123 species, 41 of which are new records for Kansas. Chironominae was the most species rich subfamily with 79 species, while Tanypodinae and Orthocladiinae were represented by 25 and 19 species, respectively. Emergence phenologies from small, replicated, experimental ponds were determined by quantitative sampling in 1988 and 1989. In both years, many taxa showed patterns of seasonal emergence, being restricted to one of the three seasons sampled, while 9 (1988) and 12 (1989) taxa emerged over most or all of the sampling periods.Cladotanytarsus spp. andPsectrocladius vernalis were the most abundant taxa in 1988 and 1989, respectively. Chironomid distribution patterns at NESA and their relevance to patterns across the state are discussed. Annotations are provided for selected taxa and new records for the state are indicated.