PhD Code: MARES_12_03:
- Host institute 1: P3 - University of Bologna
- Host institute 2: P5 - University of Algarve
- T2 - Understanding biodiversity effects on the functioning of marine ecosystems
- T6 - Habitat loss, urban development, coastal infrastructures and Marine Spatial Planning
- Airoldi Laura
- Serrao Ester
Forests of canopy-forming algae are structurally complex and highly productive habitats on temperate rocky coasts (Steneck et al. 2002). These habitats are clearly becoming rarer at local, regional and global scales at an alarming rate (Airoldi & Beck 2007, Connell et al. 2008). This is concerning because algal forests play a key role in coastal primary production, nutrient cycling and disturbance regulation, and rival corals for sheer diversity of species. The underlying driver of loss is probably a synergy of anthropogenic stressors including climate change, nutrient loading, habitat fragmentation or biotic exploitation, episodic disturbance events, overgrazing, disease and direct harvesting (Steneck et al. 2002). Lost forests tend to be replaced by organisms of lower structural complexity, such as turf-forming algae, mussels or “barrens” (Benedetti-Cecchi et al 2001). Recovery potential for lost algal forests seems to be limited by severe recruitment failure in many regions of the world. The causes probably include a combination of modified habitat and biotic conditions, demographic factors (e.g. reduced fertility) and/or low dispersal potential (Perkol-Finkel & Airoldi 2011). However, compared to adult stages, there is relatively little knowledge of the ecology of early life-history stages (Schiel & Foster 2006), limiting our ability to possibly restore algal habitats where they have been fragmented or lost.
The objective of the proposed MARES PhD project, for which The University of Bologna and the University of Algarve will join their complementary expertises and infrastructure, is to identify factors that facilitate the recovery or active restoration of damaged forests of fucoid canopy algae. Our study system will be forests of fucoid algae (Cystoseira spp and Fucus spp) along southern European coasts, in view of their widespread degradation and declared conservation priority (Annex I of the Bern Convention, and Action Plan for the Conservation of Marine Vegetation in the Mediterranean Sea).
Working with healthy and fragmented forests of canopy algae, the candidate will:
1) quantify the natural reproductive potential, dispersal and recruitment patterns. A possible consequence of fragmentation and poor habitat condition is that adult algae produce fewer viable offspring than is necessary to maintain populations, or perhaps lose their ability to produce offspring altogether. The candidate will test this possibility in two ways. First, reproductive parts will be harvested through time for a microscopic assessment of their maturity condition and of the viability (potential to settle and establish) of gametes. Second the natural local dispersal will be tracked by combining measurement of settlement at increasing distances from adults with direct measures of dispersal (e.g. labelling propagules with Toluidine Blue prior to dispersal). Multiple trials will be done to encompass as much variation in local hydrodynamic conditions as possible in extensive and fragmented forests;
2) analyse the genetic structuring and connectivity among fragmented habitat patches at multiple scales. Connectivity corresponds to effective dispersal, a process that influences genetic structure within (e.g. Alberto et al. 2011) and between (e.g., Neiva et al. 2012) populations. The loss of connectivity by fragmentation or extinction of local populations may cause genetic loss due to drift and bottleneck effects and an enhanced inbreeding rate, as a consequence of critical reduction of the effective population size. Specimens of target model species of fucoid algae will be collected at a range of spatial scales (10s m to 100s km) to assess genetic variability and differentiation within and among populations, and to estimate phylogeographic relationships among populations. This information will provide quantitative data on i) genetic differentiation at the intra- and interpopulation level, ii) gene flow at the investigated scales and iii) occurrence of populations that act as a source and/or sink of propagules. Results will provide a valuable contribution to understand natural dispersal patterns. Defining the autonomy of the sites in terms of recruitment and their individual role in sustaining recruitment in neighbouring sites is also an effective way to build and maintain resilience of natural populations;
3) identify factors limiting or facilitating settlement and establishment (post-settlement survival and growth). Propagules dispersed away from adult populations could become the founders of new populations, and thus increase habitat abundance. Such individuals, however, would need to settle and establish in different environmental conditions than those retained within forests, which may not be as favourable. Similar challenges are likely to face propagules in fragmented forests. Evidence suggests early life-history stages respond positively to conditions beneath extensive adult canopies, though information about their potential to survive in alternate conditions is scarce. Through a combination of short-term laboratory based and long-term field based experiments, the candidate will test synergistic effects of selected physical and biological factors on the settlement and establishment of early stages of fucoid algae to gain insight into the optimal conditions for their survival. The range of manipulations will be matched to those observed naturally, but will particularly focus on differences between extensive and fragmented forests. Results will be used to identify configurations most likely to facilitate good levels of natural recruitment from those likely to require intervention through direct restoration.
- Airoldi L, Beck MW (2007) Loss, status and trends for coastal marine habitats of Europe. Oceanography and Marine Biology: an Annual Review 45: 345-405
- Alberto F, Raimondi PT, Reed DC, Watson JR, Siegel DA, Mitarai S, Coelho N, Serrao EA. (2011) Isolation by oceanographic distance explains genetic structure for Macrocystis pyrifera in the Santa Barbara Channel. Molecular Ecology, 20:2543-2554
- Benedetti-Cecchi L, Pannacciulli F, Bulleri F, Moschella PS, Airoldi L, Relini G, Cinelli F (2001) Predicting the consequences of anthropogenic disturbance: large-scale effects of loss of canopy algae on rocky shores. Marine Ecology Progress Series 214:137-150
- Connell SD, Russell BD, Turner DJ, Shepherd SA, Kildea T, Miller D, Airoldi L, Cheshire A (2008) Recovering a lost baseline: missing kelp forests from a metropolitan coast. Mar Ecol Prog Ser 360: 63-72
- Neiva J, Pearson GA, Valero M, Serrao EA (2012) Drifting fronds and drifting alleles: range dynamics, local dispersal and habitat isolation shape the population structure of the estuarine seaweed Fucus ceranoides L. J Biogeog 39: 1167-1178
- Perkol-Finkel S, Airoldi L (2010) Loss and recovery potential of marine habitats: an experimental study of factors maintaining resilience in subtidal algal forests. PLoS ONE 5:e10791
- Steneck RS, Graham MH, Bourque BJ, Corbett D, Erlandson JM, Estes JA, Tegner MJ (2002) Kelp forest ecosystems: biodiversity, stability, resilience and future. Environ Cons 29: 436-459
The Ph.D. candidate will be employed as research scientist at The University of Bologna. He/she will have full benefits of the Italian public health and social insurance scheme. The EU-funded gross contribution to the employment costs of monthly Euro 2800 will result in a salary of approx. Euro 2000 per month depending on individual characteristics of the Ph.D. candidate. The candidate will work under the integrated and coordinated supervision of UNIBO and University of Algarve, and will spend 24 months at Bologna University and 12 months at University of Algarve.
The candidate is expected to produce at least three scientific publications with the supervisors: 1) a paper on natural reproductive potential, dispersal and recruitment patterns in healthy and degraded forests, 2) a paper on the genetic structuring and connectivity in healthy and degraded forests and 3) a paper on factors facilitating natural or assisted recovery. The candidate will benefit from close exchange with (inter)national projects (THESEUS, MERMAID, SHIFTING) which will facilitate work on ecological restoration in urbanized coastal environments and will ensure that the outcomes of the PhD project will have direct relevance to real case studies.