Using Long-Term Removal Data to Manage a Crown-of-Thorns Starfish Population

Abstract

Background: Removal programs are effective strategies for short-term management of Crown-of-Thorns Starfish (Acanthaster spp.) populations, especially on a small scale. However, management programs are costly, and, in order to be effective, they must be based on local Acanthaster spp. population dynamics. We have developed simple models to predict the annual number of removable A. cf. solaris along the Onna coast of western central Okinawa Island, where chronic outbreaks have continued for several decades. Methods: The Onna coastal area was divided into five sectors, and annual abundance of small A. cf. solaris individuals was used to predict the total number of removable individuals of a cohort in each sector. Three models were developed, based on size class data collected by the Onna Village Fisheries Cooperative (OVFC) for 2003-2015, according to possible patterns of recruitment and adult occurrence. Using the best-fit models selected for each of the five sectors, the number of individuals that potentially escaped removal was calculated. Results: Best-fit models were likely to differ among the five sectors instead of small differences in the coefficients of determination. The models predict differences in the number of residual starfish among sectors; the northernmost sector was predicted to have a high number of residuals and the potential density of A. cf. solaris in the sector exceeded the outbreak criterion. Conclusions: These results suggest how to allocate resources to reduce the population of A. cf. solaris along the Onna coast in 2016. The OVFC implemented a control program for A. cf. solaris based on three model predictions.

Thirty Years of Research on Crown-of-Thorns Starfish (1986–2016): Scientific Advances and Emerging Opportunities

“…Firstly, renewed outbreaks of CoTS are occurring on the Great Barrier Reef (GBR), Australia, combined with unprecedented outbreaks at many locations throughout the Indo-Pacific [1]. Secondly, outbreaks of CoTS remain a major contributor to sustained decline in coral cover at many reefs throughout the Indo-Pacific (e.g., [16,17]) and scientists and managers alike recognize the critical need to halt and reverse this decline. Preventing and/or containing CoTS outbreaks is generally considered to be one of the most feasible management actions to reduce rates of coral mortality (e.g., [7]), thereby improving the capacity of reef systems to cope with threats due to climate change and other anthropogenic disturbances [18].…”

“…This special issue (Biology, Ecology and Management of Crown-of-Thorns Starfish) reflects the latest resurgence in scientific interest and research on Acanthaster spp., unequivocally focused on better understanding the initiation and spread of outbreaks, as well as refining the capability and capacity for effective management. The papers presented in this special issue address: (i) environmental drivers of fertilization and early development [23,24]; (ii) larval nutrition, larval development and implications for the 'nutrient enrichment hypothesis' [25][26][27][28][29]; (iii) predation and implications for the 'predator removal hypothesis' [30][31][32]; (iv) factors influencing settlement [27,30]; (v) dispersal and genetics [33]; (vi) longevity, growth, and size-and-age relationship [34,35]; (vii) movement [36]; and (viii) control and management [16,37].…”

30 Years of Research on Crown-of-thorns Starfish (1986-2016): Scientific Advances and Emerging Opportunities

“…solaris occurred for more than 18 months at Molokai Island, Hawaii, but had negligible effect on local coral assemblages (Branham et al 1971). Within the Pacific, devastating effects of CoTS outbreaks on coral assemblages are mainly restricted to the central and western Pacific, including French Polynesia (Trapon et al 2011;Kayal et al 2012), Australia's GBR (Pearson and Endean 1969;De'ath et al 2012), Micronesia (Chesher 1969;Colgan 1987), and southern Japan (Nishihira and Yamazato 1974;Yamaguchi 1986;Nakamura et al 2016). In contrast, CoTS outbreaks cause minimal coral loss in the eastern Pacific (Glynn 1974(Glynn , 1976.…”

“…Secondly, outbreaks of Acanthaster spp. remain a major contributor to sustained decline in coral cover at many reefs throughout the Indo-Pacific (e.g., Nakamura et al 2016;Pisapia et al 2016) and scientists and managers alike recognize the critical need to halt and reverse this decline. Preventing and/or containing CoTS outbreaks is generally considered to be one of the most feasible management actions to reduce rates of coral mortality (e.g., De'ath et al 2012), thereby improving the capacity of reef systems to cope with threats due to sustained and ongoing climate change and other more direct anthropogenic disturbances (Anthony 2016).…”

“…This special issue (Biology, Ecology and Management of Crown-of-Thorns Starfish) reflects the latest resurgence in scientific interest and research on Acanthaster spp., unequivocally focused on better understanding the initiation and spread of outbreaks, as well as refining the capability and capacity for effective management. In all, the papers presented in this special issue address: i) environmental drivers of fertilization and early development (Allen et al 2017;Caballes et al 2017b); ii) larval nutrition, larval development and implications for the 'nutrient enrichment hypothesis ' (Nakajima et al 2016;Brodie et al 2017;Caballes et al 2017a;Mellin et al 2017;Pratchett et al 2017b); iii) predation and implications for the 'predator removal hypothesis ' (Cowan et al 2016a' (Cowan et al , 2017Messmer et al 2017); iv) factors influencing settlement (Cowan et al 2016a;Pratchett et al 2017b); v) dispersal and genetics ; vi) longevity, growth, and size-and-age relationship (Wilmes et al 2016;MacNeil et al 2017); vii) movement (Sigl and Laforsch 2016); and viii) control and management (Buck et al 2016;Nakamura et al 2016).Aside from ongoing research to address critical issues related to the effective management of CoTS outbreaks, there have also been some fundamentally new directions for CoTS research in the last decade, enabled by advances in research methods and analytical capabilities. Therefore, this review also considers some of the foremost new directions for CoTS research, related to i) systematics and biogeography, ii) genetic and genomic sampling, iii) ecological modelling and iv) projected effects of environmental change.…”