PhD Code: MARES_22_2010:
- Host institute 1: P5 - University of Algarve
- Host institute 2: P11 - Université Pierre et Marie Curie (UPMC)
- T1 - Future oceans : temperature changes - hypoxia - acidification
- T6 - Habitat loss, urban development, coastal infrastructures and Marine Spatial Planning
- Rita Borges
- Serge Planes
Oceans of the globe are subjected to increased natural or human-driven stressors. Marine protected areas (MPAs) are used to protect marine biodiversity while managing human uses. MPAs can serve two purposes: promoting local fish diversity and biomass within their borders and/or increasing the spillover of adults, larvae and eggs to fished areas beyond their borders. Understanding connectivity patterns between reef fish populations is of major importance to the design of and distance among coastal Marine Protected Areas that are part of a network. Most reef fish species have particular bi- partite life cycles with adults that live relatively attached to the demersal substrates, and a larval pelagic phase that has a large potential for dispersal, interconnecting populations (Planes et. al, 2009). Fish larvae were traditionally considered as passive dispersing long distances depending solely on currents and the extent of the plagic larval duration (PLD). However, increasing evidence shows that retention close to natal reefs can occur and that self-recruitment can be higher than expected in some coral reef fish species.
Important relevant life history traits of fish can influence their potential for dispersal. Larvae hatching from demersal eggs are more developed and can potentially show relevant behavioural patterns early in their ontogeny, that can modulate their horizontal dispersal. Species having short PLDs are less likelly of successfully finding a suitable habitat where to settle and thus are expected to disperse less than species with longer PLD. However, even in species with longer PLD's, behaviour can also influence dispersal patterns. Larvae of reef fish species can have strong swimming capabilities that can allow them to actively interact with currents and change their dispersal.
Most research on population connectivity has been developed in coral reef environments and very little is known on the factors affecting local population dynamics of temperate reef fishes. The extent of dispersal and the connectivity patterns of these populations, relevant at the ecological scale, must be known so that the role of MPA’s to sustain fisheries outside its borders and/or to increase local production can be understood and are thus major factors that should be considered in MPA management, and in the design of future MPA networks as tools of effective adaptive management in face of global and regional changes.
The Cerbère-Banyuls Natural Marine Reserve in the French Mediterranean was established in 1974. Restrictions on human use are well enforced; thus, it is probable that ecological changes have occurred since protection (Guidetti & Sala 2007; Claudet et al. 2008; Molloy et al. 2009). Artisanal and recreational fishing are allowed but the number of fishing vessels and the type of fishing gears used is limited. Within the partially protected (buffer) zone, there is a no-take and no-use zone, and the highest density of fishers occurs at the borders of the no-take zone and external borders of the buffer zone (Goñi et al. 2008). The establishment of the MPA and spatial differences in fishing effort are associated with improvements in the condition of individual fish and increases in abundance and species richness within the MPA (Dufour et al. 1995; Lloret & Planes 2003). However, little is known about the patterns of connectivity between these populations and others outside of the MPA borders.
The Arrábida Marine Park was only recently established as an MPA; it is similar to the Cerbere- Banyuls reserve both in terms of size and the spatial organization. Studies previously conducted at this area have shown that the larvae of some species seem to grow inshore close to the reefs, potentially self-recruiting locally (Beldade et al., 2006; Borges et al., 2007). Although located in the Portuguese western coast, this study area faces south and is thus protected from the NW winds and has particular good conditions to investigate reef fish assemblages; however, no direct estimates of connectivity have been investigated so far. Within the very diverse local fish assemblage, several species having important ecological roles in the nearshore reef fish assemblages, also occur in Mediterranean waters.
We intend to replicate methods of larval fish sampling (by using light traps) in order to compare the structure of nearshore larval fish assemblages in these two areas and patterns of larval retention, as well as relevant early life history traits (ELHT) of larvae, such as PLD, through otolith analysis. Connectivity patterns between populations of target commercial and ecologically relevant species common to both systems will be investigated through the use of microsatellites in order to investigate self-recruitment and the role of these populations as source of recruits to other populations). Target species will include the grouper, Epinephelus marginatus, and sparids (Diplodus spp), for which there are available microsatellites; E. Marginatus is a valuable species that has a very reduced population size in the Banyuls MPA, where a reduced number of reproducing males occur; Sparids of the genus Diplodus are also of high commercial specie sboth in the Atlantic and in the Mediterranean. Field work will be conducted in both systems; laboratorial analysis of larvae and ELHT will be conducted with Partner 5; the genetic analysis will mainly be developed with Partner 24.
Beldade, R.; R. Borges; E.J. Gonçalves.2006. Depth distribution of nearshore temperate fish larval assemblages near rocky substrates. Journal of Plankton Research; doi: 10.1093/plankt/fbl035.
Borges, R.; R. Beldade; E.J. Gonçalves 2007. Vertical structure of very nearshore larval fish assemblages in a temperate rocky coast. Marine Biology DOI 10.1007/s00227-006-0574-z.
Claudet, J., et al. 2008. Marine reserves: size and age do matter. Ecology Letters 11:481-489.
Dufour, V., J.-Y. Jouvenel, and R. Galzin. 1995. Study of a Mediterranean reef fish assemblage. Comparisons of population distributions between depths in protected and unprotected areas over one decade. Aquatic Living Resources 8:17-25.
Goñi, R., et al. 2008. Spillover from six western Mediterranean marine protected areas: evidence from artisanal fisheries. Marine Ecology Progress Series 366:159-174.
Guidetti, P., and E. Sala. 2007. Community-wide effects of marine reserves in the Mediterranean Sea. Marine Ecology Progress Series 335:43-56.
Lloret, J., and S. Planes. 2003. Condition, feeding and reproductive potential of white seabream Diplodus sargus as indicators of habitat quality and the effect of reserve protection in the northwestern Mediterranean. Marine Ecology Progress Series 248:197-208.
Molloy, P. P., I. B. McLean, and I. M. Côté. 2009. Effects of marine reserve age on fish populations: a global meta-analysis. Journal of Applied Ecology 46:743-751.
Planes, S., Jones, G.P., Thorrold, S.R. 2009 Larval dispersal connects fish populations in a network of marine protected areas. PNAS 106: 5693–5697
3 publications in peer-reviewed journals with scope in Marine Ecology and Conservation: one of the publications will target the comparison of the larval assemblages and local growth; two publications focusing the genetic structure of the target populations, its relationship with expected patterns based on early life history traits, and the implications for MPA management
Resulst will also be discussed in scientific seminars and participation in international conferences
Outreach to the general public and in particular to local stakeholders on the role of MPAs will be achieved through seminars