Ensuring Persistence of Marine Reserves: Catastrophes Require Adopting an Insurance Factor

Abstract

Abstract. When viewed across long temporal and large spatial scales, severe disturbances in marine ecosystems are not uncommon. Events such as hurricanes, oil spills, disease outbreaks, hypoxic events, harmful algal blooms, and coral bleaching can cause massive mortality and dramatic habitat effects on local or even regional scales. Although designers of marine reserves might assume low risk from such events over the short term, catastrophes are quite probable over the long term and must be considered for successful implementation of reserves. A simple way to increase performance of a reserve network is to incorporate into the reserve design a mechanism for calculating how much additional area would be required to buffer the reserve against effects of catastrophes. In this paper, we develop a method to determine this ''insurance factor'': a multiplier to calculate the additional reserve area necessary to ensure that functional goals of reserves will be met within a given ''catastrophe regime.'' We document and analyze the characteristics of two relatively well-studied types of disturbances: oil spills and hurricanes. We examine historical data to characterize catastrophe regimes within which reserves must function and use these regimes to illustrate the application of the insurance factor. This tool can be applied to any reserve design for which goals are defined by a quantifiable measure, such as a fraction of shoreline, that is necessary to accomplish a particular function. In the absence of such quantitative measures, the concept of additional area as insurance against catastrophes may still be useful.

Population persistence in marine reserve networks: incorporating spatial heterogeneities in larval dispersal

“…Multiple self-persistent reserves could provide redundancy to the network in the face of localized catastrophes (Allison et al 2003): the extinction of a single patch would not necessarily threaten population-wide persistence, and recolonization from neighboring patches may be possible. By contrast, systems in which persistence arises from network connectivity may be especially sensitive to stochastic disturbance.…”

“…In the context of marine reserve design, the potential for network persistence may be an important consideration when it is impossible to ensure that any single reserve will be selfpersistent . Moreover, a network of self-persistent reserves may be more resilient to local environmental disturbances than a networkpersistent system would be (Quinn & Hastings 1987, Allison et al 2003), although we do not consider the effects of disturbance in the present paper.…”

“…In the context of marine reserve design, the potential for network persistence may be an important consideration when it is impossible to ensure that any single reserve will be selfpersistent . Moreover, a network of self-persistent reserves may be more resilient to local environmental disturbances than a networkpersistent system would be (Quinn & Hastings 1987, Allison et al 2003), although we do not consider the effects of disturbance in the present paper.For the purpose of evaluating long-term persistence, larval dispersal is commonly described by a kernel, which is the spatial probability distribution for the destination (settlement site) of larvae spawned at a particular location (Largier 2003). In its simplest form, a kernel can be formulated in terms of 2 parameters: an advective length scale (L A ) describing the mean unidirectional transport of larvae over some time interval, and a stochastic length scale (L S ) describing variation in the mean flow over that time interval as well as smaller-scale fluctuations and turbulence (Largier 2003, Byers & Pringle 2006.…”

Low genetic diversity in a marine nature reserve: re-evaluating diversity criteria in reserve design

“…While these characteristics enable effective management, they are likely to make reserve populations more susceptible to environmental change (Hanski 2001), extinction (Frankham 1995(Frankham , 1998 and inbreeding if the effective population size is small (Wright 1921;Charlesworth & Charlesworth 1987). The level of isolation and the rate of migration between mainland and reserve populations will determine: (i) the amount of buffering the reserve is afforded from local catastrophes by the external input of larvae (Allison et al 2003); (ii) the usefulness of the reserve as a source of larvae for mainland populations (Chiappone & Sealey 2000); and (iii) the amount of genetic differentiation between reserve and mainland populations.…”

Testing the consistency of connectivity patterns for a widely dispersing marine species

“…Genetic connectivity refers to the degree to which gene flow affects evolutionary processes within populations, whereas demographic connectivity refers to the degree to which population growth and vital rates are affected by dispersal and recruitment (Lowe and Allendorf, 2010). Understanding connectivity is important because it controls the following: (1) a population's buffering potential from local catastrophes and therefore its extinction risk (Allison et al, 2003); (2) a population's potential as a source of new individuals to other populations; (3) the level of genetic mixing between populations (Bell and Okamura, 2005;Bell, 2008); and (4) a population's susceptibility to disease or pollution, the so-called 'dark-side' of connectivity (Hughes et al, 2010).…”