| Popis: |
With the marine environment subjected to ever increasing anthropogenic pressures resulting in biodiversity and habitat losses, there is an urgent need to implement effective management and conservation strategies to limit these losses. One such strategy is the designation of Marine Protected Area (MPA) networks, with the central concept that individual MPAs are connected to its neighbours within the network However, determining scales of connectivity in an environment that varies considerably both spatially and temporally is inherently difficult. Larval dispersal is a main driver of population connectivity, and planktonic larval duration (PLD) is frequently used to infer dispersal distance. Thus far studies have predominantly focused on fish and tropical species, using approaches such as larval dispersal modelling, otolith microchemistry or genetic estimates of connectivity. This thesis aimed to assess the levels of connectivity in a range of benthic invertebrates characteristic of offshore shelf seas of the Northeast Atlantic, at a range of spatial and temporal scales. This was achieved by: (1) examining the variation in PLDs of a typical benthic assemblage, then using this information to examine the variation in realised dispersal at multiple locations using particle tracking software; (2) assessing habitat preferences for the same species, and exploring how the distribution of broad habitats would affect connectivity of species; and (3) using microsatellite markers to determine the genetic structure of the exploited scallop Pecten maximus at both a localised scale (Isle of Man) and a regional scale covering over half its range. While biological variation, in the form of PLD, did affect dispersal potential of common benthic invertebrates, it was the physical factors of hydrographic regime and substrate type within a species given dispersal range that played the most important role in determining ultimate dispersal distance and location. Additionally, the scale of genetic structure of the scallop Pecten maximus, with Norway genetically distinct from Scotland, Ireland and Isle of Man but weaker or no structure within those regions, highlighted the interaction of biological and physical factors. Ultimately, this thesis has provided valuable insight into the drivers of connectivity in the marine benthos, but further work, particularly more collaborative studies across multiple fields, is required if MPAs are to achieve their aims in the face of a changing environment. |
