Understanding the effectiveness of marine protected areas using genetic connectivity patterns and Lagrangian simulations

Abstract

Aim: To explore the patterns of connectivity between marine protected areas (MPAs) and neighbouring non-protected areas and the scale at which the benefits of MPAs are expected using the white sea bream as model species. Location: Marine protected area of Torre Guaceto (TGMPA, Italy) in the south Adriatic Sea. Methods: A multidisciplinary approach was used combining (1) a genetic survey using 12 highly informative microsatellite loci of samples collected within the MPA and in several locations up to 100 km from the MPA; and (2) larval trajectories using Lagrangian simulations based on an oceanographical model of the region that includes specific data on early life-history traits. Both genetic and simulation studies were temporarily replicated during two consecutive years. Results: The overall genetic homogeneity observed indicates that the TGMPA is not isolated and that there is genetic connectivity among locations across a scale of at least ~200 km. A high degree of connectivity between the TGMPA and neighbouring areas is in agreement with Lagrangian simulations, which indicate that white sea bream larvae can be transported over large distances up to about 300 km. Trajectories released from the TGMPA showed that on average, 12.75% of the larvae remains within the TGMPA, while the rest travel south towards non-protected areas. Main conclusions: Our findings highlight the potential benefits of effectively enforced MPAs for neighbouring or relatively distant non-protected fishing areas and the potential connection with other MPAs at regional scale. Combining genetics and modelling can provide a general framework to investigate the role of connectivity in MPA design that can be easily extended to other species and geographical areas

Pelagic early life stages promote connectivity in the demersal labrid Choerodon rubescens

“…Although the minimum numbers of loci and individuals required to provide a robust test for genetic differentiation in marine species with pelagic ELS have been the subject of much debate (Hellberg, 2009;Paetkau et al, 2004), the number of loci used in the present study was comparable with those employed in many similar studies (e.g., Ball et al, 2007;Bekkevold et al, 2005;Buonaccorsi et al, 2002;Damerau et al, 2012;Pujolar et al, 2013). Furthermore, comparisons of simulated and empirical data sets, by Hale et al (2012), indicate that the use of sample sizes greater than ca 25-30 individuals does not have a significant impact on estimates of genetic differentiation.…”

“…This study highlights the value of employing complementary methods, such as genetic and otolith microchemistry analyses, to investigate connectivity in marine species, and, in particular, for assessing the likely extent of dispersal during different phases of the life cycle (e.g., see Berry et al, 2012a;Collins et al, 2013;Pujolar et al, 2013).…”

Mismatch in early life traits between settlers and recruits in a Mediterranean fish: Clue of the relevance of the settlement tail?

“…The white seabream, that clearly responds to protection from fi shing by increasing in density and size (Guidetti 2006, Guidetti and Sala 2007, Di Franco et al 2012a, 2013, usually inhabits the littoral zone in shallow waters down to about 50 m (Tortonese 1965, Harmelin-Vivien et al 1995. Adults produce eggs and larvae that develop in pelagic waters for a period ranging from 13 to 28 days (Macpherson and Raventos 2006, Di Franco and Guidetti 2011, Di Franco et al 2011 and that are able to disperse over hundreds of kilometres (Di Franco et al 2012a, 2012b, Pujolar et al 2013.…”

“…Adults produce eggs and larvae that develop in pelagic waters for a period ranging from 13 to 28 days (Macpherson and Raventos 2006, Di Franco and Guidetti 2011, Di Franco et al 2011 and that are able to disperse over hundreds of kilometres (Di Franco et al 2012a, 2012b, Pujolar et al 2013. Then larvae metamorphose and settle at about 1 cm total length (TL) in shallow (about 2 m depth) coastal benthic habitats, mainly within small bays with mixed sand and rocky bottom (Tortonese 1965, Harmelin-Vivien et al 1995see Bussotti and Guidetti 2011 for specifi c evidence referred to the study area).…”

“…Data collection. One hundred forty settlers of Diplodus sargus sargus (i.e., 1-1.5 cm TL) were collected between 8 June and 15 June 2009, approximately 10-14 days after the settlement peak, occurred at the end of May-very beginning of June 2009 (Di Franco et al 2013). Settlers were collected using a dip net at 14 sampling sites along the study area, with 10 settlers collected at each site.…”