Quantifying Dispersal Diversity in Atlantic Marine Communities

Background/Question/Methods

To understand and predict how regional diversity changes under directed environmental pressure, there needs to be more focus on monitoring broad-scale spatially connected communities (metacommunities). Metacommunities are linked through dispersal, with previous research showing that moderate rates of dispersal enhance community stability and allow for ecological complexity. Metacommunity models typically assume rates of dispersal are either equal among species or hierarchically structured by trophic level, but average rates alone may not capture all the variation for stability and complexity. Diversity in dispersal types, based on species morphological and behavioral traits, may be as important for shaping communities. Moderate variation in dispersal ability, based on these traits, may capture the state of a metacommunity more accurately. We propose to use dispersal linked traits as a metric of functional diversity to inform on metacommunity function. The Newfoundland and Labrador shelves (NFL) metacommunity has been well studied, with species abundance data collected by Fisheries and Oceans Canada (DFO) using stratified trawl surveys accessible from 1995 to 2017. Measures for dispersal traits of marine fish were collected from open source data reported in FishBase. Trait data was used to cluster species into functional groups to determine the spatiotemporal variation of dispersal diversity.

Results/Conclusions

Dispersal traits for marine species were identified from literature resulting in 17 traits of interest. After filtering the NFL region for species with available data, a community of 109 marine fish were categorized into 48 functional groups using dispersal linked traits. A PCoA was run with the first two principal axes explaining 65% of the variation. Effective dispersal diversity was calculated on Shannon’s diversity, then mapped using the same stratified method from the DFO for every year from 1995 to 2017. Preliminary spatiotemporal trends revealed that the northern part of the shelf has exhibited a decline in dispersal diversity since 2005. Moving forward, dispersal diversity will be compared to effective species richness, ocean depth, ocean currents and temperature patterns of the system, as well as mean rate of biomass change for the region to determine any correlation to community stability and resilience. This study aims to provide a better understanding of how connected the region is and if dispersal diversity can be used as a measure for metacommunity function and health under environmental pressure.