scholarly journals Patterns, causes, and consequences of marine larval dispersal

2015 ◽  
Vol 112 (45) ◽  
pp. 13940-13945 ◽  
Author(s):  
Cassidy C. D’Aloia ◽  
Steven M. Bogdanowicz ◽  
Robin K. Francis ◽  
John E. Majoris ◽  
Richard G. Harrison ◽  
...  
Keyword(s):  
Spatial Scale ◽  
Spatial Genetic Structure ◽  
Marine Reserve ◽  
Local Population ◽  
Logistic Models ◽  
Strong Relationship ◽  
Parentage Analysis ◽  
Population Connectivity ◽  
Dispersal Kernel ◽  
Marine Population

Quantifying the probability of larval exchange among marine populations is key to predicting local population dynamics and optimizing networks of marine protected areas. The pattern of connectivity among populations can be described by the measurement of a dispersal kernel. However, a statistically robust, empirical dispersal kernel has been lacking for any marine species. Here, we use genetic parentage analysis to quantify a dispersal kernel for the reef fish Elacatinus lori, demonstrating that dispersal declines exponentially with distance. The spatial scale of dispersal is an order of magnitude less than previous estimates—the median dispersal distance is just 1.7 km and no dispersal events exceed 16.4 km despite intensive sampling out to 30 km from source. Overlaid on this strong pattern is subtle spatial variation, but neither pelagic larval duration nor direction is associated with the probability of successful dispersal. Given the strong relationship between distance and dispersal, we show that distance-driven logistic models have strong power to predict dispersal probabilities. Moreover, connectivity matrices generated from these models are congruent with empirical estimates of spatial genetic structure, suggesting that the pattern of dispersal we uncovered reflects long-term patterns of gene flow. These results challenge assumptions regarding the spatial scale and presumed predictors of marine population connectivity. We conclude that if marine reserve networks aim to connect whole communities of fishes and conserve biodiversity broadly, then reserves that are close in space (<10 km) will accommodate those members of the community that are short-distance dispersers.

scholarly journals The Behaviour and Ecology of Austrolittorina antipodum and Austrolittorina cincta: Models for Marine Reserve Connectivity Studies

2021 ◽  
Author(s):  
◽  
Jennifer Vander Veur
Keyword(s):  
Gene Flow ◽  
Larval Mortality ◽  
Marine Reserve ◽  
Sex Ratios ◽  
Marine Conservation ◽  
Population Connectivity ◽  
Adult Density ◽  
Population Surveys ◽  
Multiple Peaks ◽  
High Shore

<p>Determining the magnitude of dispersal and connectivity between populations has important implications for marine conservation. Species with limited dispersal capabilities exhibit restricted gene flow leading to isolation and, ultimately, differentiated populations. In this ecological study I investigated the gastropods Austrolittorina antipodum (Philippi, 1847) and Austrolittorina cincta (Quoy and Gaimard, 1833) to determine how ecology and behaviour influence the dispersal and connectivity of these species. The aim of this study was to determine population size and structure, settlement, fecundity, and adult movement rates. Methodologies included: population surveys, deployment of settlement pads and adult density manipulations, dissections, and a tagging study. These elements of a species ecology and behaviour can enhance or restrict population connectivity by: cohort partitioning resulting from habitat requirements, fluctuating settlement due to variable larval mortality or adult densities impacting dispersal, skewed sex ratios and effective populations sizes altering larval production, and adult movement leading to behavioural isolation or facilitating gene flow, along with other possible effects. Population surveys revealed both species had a Vermeij (1972) "type 1 distribution" (shell size increasing from the low to high shore), with the highest density of individuals on the low shore and the majority of mature adults on the high shore. Overall, A. antipodum was 16 times more abundant than A. cincta. Shifts to a smaller mean size of both species, along all shore heights following periods of peak settlement indicates settlers are potentially triggering competitive interactions or ontogenetic migrations in other cohorts.Settlement surveys revealed that peak settlement for Austrolittorina spp. was from February to April, declining at the beginning of March. Multiple peaks in settlement may act as a buffer limiting the potential of stochastic events to hinder dispersal during reproductive seasons. Settlement rates were not affected by adult density in control treatments; however, settlement was higher on pads deployed within adult populations compared to pads deployed adjacent to adult populations, suggesting the presences of adults has some effect on settlement. Fecundity results revealed A. antipodum to have more mature females than A. cincta, with males of both species reaching sexual maturity before females. Sex ratios of both species were skewed towards more females, with effective population sizes that included approximately 88% of each species population. A. antipodum’s larger population may be due to variation between the species' demographics, such as the distribution of mature females and juveniles leading to greater spawning success and juvenile survivorship. Tagging transplant/translocation experiments used to examine movement revealed that both species traveled similar distances. On average A. antipodum traveled 24.1m (±23.5m) and A. cincta traveled 18.7m (±16m) in eight months. There was no evidence of behavioural isolation occurring between low and high shore individuals. The wide ranging movements of adults indicated adults have the potential to maintain population connectivity on small scales. The findings of this study suggest both species facilitate dispersal with multiple peaks in settlement, large effective populations, and high adult mobility. Behavioural variation between the species appears to affect population connectivity, with the distribution of A. antipodum demographics potentially enhancing connectivity.</p>

scholarly journals Probability of successful larval dispersal declines fivefold over 1 km in a coral reef fish

2011 ◽  
Vol 279 (1735) ◽  
pp. 1883-1888 ◽  
Author(s):  
Peter M. Buston ◽  
Geoffrey P. Jones ◽  
Serge Planes ◽  
Simon R. Thorrold
Keyword(s):  
Larval Dispersal ◽  
Isolation By Distance ◽  
Dispersal Distance ◽  
Population Connectivity ◽  
Marine Ecology ◽  
Sea Anemones ◽  
Marine Population ◽  
Amphiprion Percula ◽  
Distance Distributions ◽  
Dispersal Distances

A central question of marine ecology is, how far do larvae disperse? Coupled biophysical models predict that the probability of successful dispersal declines as a function of distance between populations. Estimates of genetic isolation-by-distance and self-recruitment provide indirect support for this prediction. Here, we conduct the first direct test of this prediction, using data from the well-studied system of clown anemonefish ( Amphiprion percula ) at Kimbe Island, in Papua New Guinea. Amphiprion percula live in small breeding groups that inhabit sea anemones. These groups can be thought of as populations within a metapopulation. We use the x- and y -coordinates of each anemone to determine the expected distribution of dispersal distances (the distribution of distances between each and every population in the metapopulation). We use parentage analyses to trace recruits back to parents and determine the observed distribution of dispersal distances. Then, we employ a logistic model to (i) compare the observed and expected dispersal distance distributions and (ii) determine the relationship between the probability of successful dispersal and the distance between populations. The observed and expected dispersal distance distributions are significantly different ( p < 0.0001). Remarkably, the probability of successful dispersal between populations decreases fivefold over 1 km. This study provides a framework for quantitative investigations of larval dispersal that can be applied to other species. Further, the approach facilitates testing biological and physical hypotheses for the factors influencing larval dispersal in unison, which will advance our understanding of marine population connectivity.

scholarly journals Is there low maternal genetic variation in West Asian populations of leopard?

2020 ◽  
Vol 65 (4) ◽  
pp. 701-708
Author(s):  
Mohammad S. Farhadinia ◽  
Mohammad Reza Ashrafzadeh ◽  
Helen Senn ◽  
Sohrab Ashrafi ◽  
Hamid Farahmand ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phylogenetic Trees ◽  
Nadh Dehydrogenase ◽  
Spatial Genetic Structure ◽  
Population Connectivity ◽  
The Caucasus ◽  
Cold Environments ◽  
Asian Populations ◽  
Low Diversity ◽  
Amova Analysis

Abstract Persian leopards Panthera pardus saxicolor have been extirpated from over 84% of their historic range and are now limited to rugged landscapes of West Asia and the Caucasus. Understanding and maintaining genetic diversity and population connectivity is important for preventing inbreeding and genetic drift, both of which can threaten population viability. All previous analyses of intraspecific genetic variation of West Asian leopards based on the NADH dehydrogenase subunit 5 gene have reported low mitogenomic diversity. In the current study, we sequenced 959 bp of the mtDNA cytochrome b gene to describe the spatial genetic structure of 22 wild Persian leopards across Iran, which hosts most of the subspecies extant range. The findings based on phylogenetic trees and median-joining network indicated that leopards from Iran formed a distinct subclade, i.e., P. p. saxicolor. The AMOVA analysis showed significant differentiation (88.55%) between the subclades of Persian leopards and other Asian leopards. The lowest levels of haplotype (0.247) and nucleotide (0.00078) diversity were estimated in Persian leopards from Iran. Mitochondrial genome sequencing revealed only two closely related haplotypes. There was no evidence for recent sudden demographic expansion scenario in Persian leopards. The low diversity in cytochrome b gene could potentially be brought about by selective pressure on mitochondria to adapt to oxidative stress and higher metabolic rates in cold environments.

scholarly journals A connectivity portfolio effect stabilizes marine reserve performance

2020 ◽  
Vol 117 (41) ◽  
pp. 25595-25600
Author(s):  
Hugo B. Harrison ◽  
Michael Bode ◽  
David H. Williamson ◽  
Michael L. Berumen ◽  
Geoffrey P. Jones
Keyword(s):  
Marine Reserves ◽  
Marine Reserve ◽  
Management Strategies ◽  
Temporal Stability ◽  
Parentage Analysis ◽  
Larval Supply ◽  
Dispersal Patterns ◽  
Temporal Fluctuations ◽  
Local Populations ◽  
Portfolio Effect

Well-managed and enforced no-take marine reserves generate important larval subsidies to neighboring habitats and thereby contribute to the long-term sustainability of fisheries. However, larval dispersal patterns are variable, which leads to temporal fluctuations in the contribution of a single reserve to the replenishment of local populations. Identifying management strategies that mitigate the uncertainty in larval supply will help ensure the stability of recruitment dynamics and minimize the volatility in fishery catches. Here, we use genetic parentage analysis to show extreme variability in both the dispersal patterns and recruitment contribution of four individual marine reserves across six discrete recruitment cohorts for coral grouper (Plectropomus maculatus) on the Great Barrier Reef. Together, however, the asynchronous contributions from multiple reserves create temporal stability in recruitment via a connectivity portfolio effect. This dampening effect reduces the variability in larval supply from individual reserves by a factor of 1.8, which effectively halves the uncertainty in the recruitment contribution of individual reserves. Thus, not only does the network of four marine reserves generate valuable larval subsidies to neighboring habitats, the aggregate effect of individual reserves mitigates temporal fluctuations in dispersal patterns and the replenishment of local populations. Our results indicate that small networks of marine reserves yield previously unrecognized stabilizing benefits that ensure a consistent larval supply to replenish exploited fish stocks.

Moving beyond the current paradigm in marine population connectivity: are adults the missing link?

2013 ◽  
Vol 15 (2) ◽  
pp. 242-254 ◽  
Author(s):  
Michael G Frisk ◽  
Adrian Jordaan ◽  
Thomas J Miller
Keyword(s):  
Population Connectivity ◽  
Missing Link ◽  
Marine Population ◽  
Current Paradigm

scholarly journals Not All Larvae Stay Close to Home: Insights into Marine Population Connectivity with a Focus on the Brown Surgeonfish (Acanthurus nigrofuscus)

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Jeff A. Eble ◽  
Luiz A. Rocha ◽  
Matthew T. Craig ◽  
Brian W. Bowen
Keyword(s):  
Resource Planning ◽  
Reef Fishes ◽  
Population Connectivity ◽  
Genetic Connectivity ◽  
Dispersal Ability ◽  
Small Range ◽  
Long Distance ◽  
Larval Recruitment ◽  
Marine Population ◽  
Acanthurus Nigrofuscus

Recent reports of localized larval recruitment in predominately small-range fishes are countered by studies that show high genetic connectivity across large oceanic distances. This discrepancy may result from the different timescales over which genetic and demographic processes operate or rather may indicate regular long-distance dispersal in some species. Here, we contribute an analysis of mtDNA cytochromebdiversity in the widely distributed Brown Surgeonfish (Acanthurus nigrofuscus;N=560), which revealed significant genetic structure only at the extremes of the range (ΦCT=0.452;P<.001). Collections from Hawaii to the Eastern Indian Ocean comprise one large, undifferentiated population. This pattern of limited genetic subdivision across reefs of the central Indo-Pacific has been observed in a number of large-range reef fishes. Conversely, small-range fishes are often deeply structured over the same area. These findings demonstrate population connectivity differences among species at biogeographic and evolutionary timescales, which likely translates into differences in dispersal ability at ecological and demographic timescales. While interspecific differences in population connectivity complicate the design of management strategies, the integration of multiscale connectivity patterns into marine resource planning will help ensure long-term ecosystem stability by preserving functionally diverse communities.

scholarly journals Observations of Migrant Exchange and Mixing in a Coral Reef Fish Metapopulation Link Scales of Marine Population Connectivity

2013 ◽  
Vol 104 (4) ◽  
pp. 532-546 ◽  
Author(s):  
John B. Horne ◽  
Lynne van Herwerden ◽  
Sheena Abellana ◽  
Jennifer L. McIlwain
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Population Connectivity ◽  
Marine Population

scholarly journals Complementarity and discriminatory power of genotype and otolith shape in describing the fine-scale population structure of an exploited fish, the common sole of the Eastern English Channel

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241429
Author(s):  
Marine Randon ◽  
Olivier Le Pape ◽  
Bruno Ernande ◽  
Kélig Mahé ◽  
Filip A. M. Volckaert ◽  
...  
Keyword(s):  
Population Structure ◽  
Spatial Scale ◽  
Discriminatory Power ◽  
Supervised Machine Learning ◽  
English Channel ◽  
Fine Spatial Scale ◽  
Otolith Shape ◽  
Marine Population ◽  
The Common ◽  
Common Sole

Marine organisms show population structure at a relatively fine spatial scale, even in open habitats. The tools commonly used to assess subtle patterns of connectivity have diverse levels of resolution and can complement each other to inform on population structure. We assessed and compared the discriminatory power of genetic markers and otolith shape to reveal the population structure on evolutionary and ecological time scales of the common sole (Solea solea), living in the Eastern English Channel (EEC) stock off France and the UK. First, we genotyped fish with Single Nucleotide Polymorphisms to assess population structure at an evolutionary scale. Then, we tested for spatial segregation of the subunits using otolith shape as an integrative tracer of life history. Finally, a supervised machine learning framework was applied to genotypes and otolith phenotypes to probabilistically assign adults to subunits and assess the discriminatory power of each approach. Low but significant genetic differentiation was found among subunits. Moreover, otolith shape appeared to vary spatially, suggesting spatial population structure at fine spatial scale. However, results of the supervised discriminant analyses failed to discriminate among subunits, especially for otolith shape. We suggest that the degree of population segregation may not be strong enough to allow for robust fish assignments. Finally, this study revealed a weak yet existing metapopulation structure of common sole at the fine spatial scale of the EEC based on genotypes and otolith shape, with one subunit being more isolated. Our study argues for the use of complementary tracers to investigate marine population structure.

scholarly journals Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic

AMBIO ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 163-173 ◽  
Author(s):  
Kjell Magnus Norderhaug ◽  
Kjell Nedreaas ◽  
Mats Huserbråten ◽  
Even Moland
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Local Population ◽  
Population Connectivity ◽  
Strongylocentrotus Droebachiensis ◽  
Predatory Fish ◽  
Ne Atlantic ◽  
Laminaria Hyperborea ◽  
Fish Stocks ◽  
Coastal Fisheries

AbstractIn this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduction coincided with the urchin bloom. From this circumstantial evidence, we hypothesize that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.

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