Anthropogenic Harvesting Pressure and Changes in Life History: Insights from a Rocky Intertidal Limpet

Abstract

The importance of large breeding individuals for maintaining the health of marine fish and invertebrate populations has long been recognized. Unfortunately, decades of human harvesting that preferentially remove larger individuals have led to drastic reductions in body sizes of many of these species. Such size-selective harvesting is particularly worrisome for sequentially hermaphroditic species where the larger size classes are composed primarily of one sex. Whether these species can maintain stable sex ratios under sustained harvesting pressure depends on the level of plasticity of their life-history traits. Here, we show that populations of a marine limpet (Lottia gigantea) can adjust a fundamental aspect of their life history (the timing of sex change) when subjected to size-selective harvesting. As predicted by theoretical models, individuals from harvested populations change sex at smaller sizes and grow at slower rates compared to individuals from protected populations. In addition, the relative size at which the change from male to female occurs remains constant (∼0.75; size at sex change/maximum size) across populations, regardless of harvesting pressure. Our results show that populationlevel demographic and life-history data, in conjunction with existing theory, can be sufficient to predict the responses of sequential hermaphrodites to harvesting pressure. Furthermore, they suggest such species can potentially adapt to size-selective harvesting.

The influence of simulated exploitation on Patella vulgata populations: protandric sex change is size‐dependent

“…; Hawkins et al. ), Chile (Oliva and Castilla ; Duran and Castilla ), Mexico, and California (Pombo and Escofet ; Fenberg and Roy , ).…”

“…Although it changes sex from male to female as it grows in size, in common with other exploited species (e.g., some Patella spp., C. oculus, and L. gigantea ), few studies have addressed experimentally the potential implications of human exploitation on demographic sex ratios (but see Rivera‐Ingraham et al. ; Fenberg and Roy ; for descriptive data on protected and exploited populations). This reflects the difficulty of following sex change in an individual through its life (but see Wright and Lindberg ; Le Quesne and Hawkins ).…”

The exploitation of limpets in a Mediterranean Marine Protected Area: assessing the effectiveness of protection in the intertidal zone

“…Kido & Murray, 2003;Branch & Odendaal, 2003;Martins et al, 2011;López et al, 2012). Highly vulnerable species are more likely to benefit from the establishment of protected areas, as demonstrated by case studies on large limpets that are often present within MPAs and other protected areas (Fenberg & Roy, 2012;Espinosa et al, 2014;García-Gómez et al, 2015). The Sinis MPA was established more than fifteen years ago in an area where human pressure on marine resources was intense (Casola et al, 2014;Pieraccini et al, 2017) and where the gathering of intertidal organisms was frequently performed as a recreational activity by local communities (Coppa et al, 2012).…”

“…Several case studies have demonstrated declines in limpet populations as a consequence of human harvesting (Ferraz et al, 2001;Weber & Hawkins, 2002;Navarro et al, 2005;Sagarin et al, 2007;Fenberg & Roy, 2012), especially in populated areas. Harvesting intensity is often limited by the physical features of an area, which can reduce the number of collectors visiting a site (Garcia & Smith, 2013).…”

The Distribution and Accumulation of Chemical Elements in the Ecosystem of Lake Ilmenskoe

“…Due to the natural and anthropogenic factors complex geo-chemical element associations are forming in gastropod shells and muscles. As a result it may change organism functions, and exhaust adaptive resources [5]- [8].…”