Estimating dispersal distance in the deep sea: challenges and applications to marine reserves

Abstract

Population connectivity refers to the exchange of individuals among populations: it affects gene flow, regulates population size and function, and mitigates recovery from natural or anthropogenic disturbances. Many populations in the deep sea are spatially fragmented, and will become more so with increasing resource exploitation. Understanding population connectivity is critical for spatial management. For most benthic species, connectivity is achieved by the planktonic larval stage, and larval dispersal is, in turn, regulated by complex interactions between biological and oceanographic processes. Coupled biophysical models, incorporating ocean circulation and biological traits, such as planktonic larval duration (PLD), have been used to estimate population connectivity and generate spatial management plans in coastal and shallow waters. In the deep sea, knowledge gaps in both the physical and biological components are delaying the effective use of this approach. Here, we review the current efforts in conservation in the deep sea and evaluate (1) the relevance of using larval dispersal in the design of marine protected areas and (2) the application of biophysical models in the study of population connectivity. Within biophysical models, PLD can be used to estimate dispersal distance. We propose that a PLD that guarantees a minimum dispersal distance for a wide range of species should be used in the planning of marine protected areas in the deep sea. Based on a review of data on species found at depths >200 m, a PLD of 35 and 69 days ensures a minimum distance for 50 and 75%, respectively, of eurybathic and deep-sea species. We note that more data are required to enhance accuracy and address the high variability in PLD between and within taxonomic groups, limiting generalizations that are often appealing to decision-makers. Given the imminent expansion of resource exploitation in the deep sea, data relevant to spatial management are needed urgently.

Biophysical and Population Genetic Models Predict the Presence of “Phantom” Stepping Stones Connecting Mid-Atlantic Ridge Vent Ecosystems

“…For environmental management plans for the MAR to be refined, further studies including taxa with different life-history strategies than bathymodiolin mussels are necessary. For example, vent species with shorter PLDs than Bathymodiolus, such as several polychaetes and gastropods [35], may disperse over much smaller distances and may require more closely spaced and/or larger MPAs for effective conservation. Closer spacing of MPAs would allow species to disperse across areas devastated by mining and reach a new protected zone, and larger MPAs would promote sustainability of populations within the conservation area.…”

Exploring the Ecology of Deep-Sea Hydrothermal Vents in a Metacommunity Framework

“…The biotic factor most widely believed to influence dispersal potential in vent species is planktonic larval duration (Hilario et al, 2015). Larvae may be planktotrophic, feeding in the water column, and thus able to survive for long periods before needing to find a suitable location to settle.…”

On the Use of Maps and Models in Conservation and Resource Management (Warning: Results May Vary)

“…It is time to recognize that in order to improve the representation of marine habitats, establishing or predicting their spatial extent and distribution may not be enough (Spalding et al, 2016). When characterizing the environment for conservation and management, we need to recognize the importance of elements such as life history (Kindsvater et al, 2016), prey-predator dynamics (Chakraborty et al, 2013), community ecology (Pitcher et al, 2012), population biology (Sherman et al, 2016), structure and dynamics , connectivity (Hilário et al, 2015), dispersal (Beier et al, 2011), sensitivity to changes , and ecosystem services (Spalding et al, 2016).…”

“…To better understand how we can achieve such complex integration of variables, more research and data are needed (Broderick, 2015;Buhl-Mortensen et al, 2015;Hilário et al, 2015), in addition to cross-disciplinary collaborations that will improve the quantity and quality of information available for decision-making (Lent, 2015;Bisack and Magnusson, 2016). A promising endeavor in that vein is the Ecological Marine Units (EMUs) project (Sayre et al, 2017), which offers a baseline three-dimensional global map of marine ecosystems.…”

“…While marine ecosystems and sciences are complex, decisionmakers and the public are drawn to simple scientific communication Hilário et al, 2015;Tulloch et al, 2016), and sound and informed choices in conservation require effective communication that reaches the multiple audiences involved in the planning process (Fischhoff, 2013;Wright, 2016). We have a responsibility as scientists to make our results and recommendations understandable for the stakeholders and to fit their needs (Groffman et al, 2010;Duarte, 2014;Broderick, 2015;Mea et al, 2016).…”