1 Rutgers University – 14 College Farm Rd. New Brunswick, NJ 08901, United States
2Instituto de Ciencias Ambientales y Evolutivas (ICAEV) – Universidad Austral de Chile, 5090000 Valvidia, Chile, Chile
3 Pontifical Catholic University of Rio de Janeiro (PUC-Rio) – 1PUC-Rio – Pontifıcia Universidade Catolica do Rio de Janeiro Caixa Postal 38097 Rio de Janeiro, RJ, Brazil, Brazil
4 CRIOBE, USR 3278, CNRS–EPHE–UPVD, Laboratoire d’Excellence “CORAIL”, – criobe – 58 Avenue Paul Alduy, 66860 Perpignan, France
5 U. Melbourne – ARC Centre of Excellence for Environmental Decisions, School of Botany, The University of Melbourne, Parkville, Melbourne, VIC 3010, Australia, Australia
6 King Abdullah University of Science and Technology (KAUST) – Thuwal, Saudi Arabia
7 Woods Hole Oceanographic Institution (WHOI) – 266 Woods Hole Road Woods Hole, MA 02543-1050, United States
8IIRD – UMR250 ENTROPIE (Institut de Recherche pour le Developpement, Universite de la Reunion, Centre National de la Recherche Scientifique), BP A5, Noumea, 98848, New Caledonia, New
Caledonia
9Woods Hole Oceanographic Institution (WHOI) – 86 Water St, Woods Hole, MA 02543, United States
10 ARC Centre of Excellence for Coral Reef Studies (CoralCoE) – ARC Centre of Excellence for Coral Reef StudiesJames Cook University TownsvilleQueensland 4811 Australia, Australia
11 Centre de recherches insulaires et observatoire de l’environnement (CRIOBE) – Universit´e de Perpignan Via Domitia, Ecole Pratique des Hautes Etudes, Centre National de la Recherche
Scientifique : USR3278 – BP 1013 Papetoiai 98729 PAPETOAI, France
The scales over which offspring disperse is critical for understanding ecology and evolution in the ocean. At the moment, most estimates suggesting short-distance dispersal are based on di- rect ecological observations of dispersing individuals, while evolutionary estimates often suggest greater homogeneity among populations. Reconciling these two approaches and their seemingly competing perspectives on dispersal has been a major challenge. Here we show that evolutionary and ecological measurements of dispersal can agree, if carefully calculated and compared. In populations of the orange clownfish (Amphiprion percula), we found that evolutionary isolation by distance methods closely matched an exhaustive set of direct larval dispersal observations in two separate time periods. Our results suggest that carefully applied evolutionary methods, which are often less expensive, can be broadly relevant for understanding ecological dispersal across the tree of life.
∗Speaker
†Corresponding author: malin.pinsky@rutgers.edu
The ghost in the machine: a review of the biology behind biophysical models of marine
larval dispersal
Stephen Swearer ∗ 1, Eric Treml 1, Jeff Shima 2
1 University of Melbourne – School of BioSciences, Parkville, VIC 3010, Australia
2Victoria University of Wellington – School of Biological Sciences, New Zealand
Despite its fundamental importance to understanding the ecology and evolution of benthic marine organisms, dispersal is arguably the least understood demographic process in the sea.
Whether an individual larva is ultimately successful in dispersing from its birthplace to its recruit location depends on the culmination of a diverse suite of intrinsic and extrinsic processes operating in early life. Empirically generating this level of insight into the connectivity process, even for a handful of species, has been immensely difficult because of the challenges of studying and quantifying dispersal in the sea. As such, most estimates of dispersal are based on theoretical estimates of potential dispersal trajectories from biophysical models. Although there is a long history of larval dispersal modelling, there has been no review of this extensive body of research.
Here we present a systematic review of this literature to ask the following questions:
Is there any systematic bias in the distribution of research effort based on geographical or taxonomic coverage?
Are hydrodynamic models resolving ocean circulation at scales relevant to the dispersal process under study?
Where, when and how many particles are being tracked and is it sufficient to capture the spatio- temporal variability in dispersal?
How much biological and behavioural complexity is being incorporated into Lagrangian particle tracking models and what, if any, stages of the dispersal process are not being well captured? We show that despite the increasing number of studies applying biophysical models, there remain considerable taxonomic and geographic biases, model resolution and particle number limits despite increases in computational efficiency, and very few studies with realistic biology. These
There and back again: patterns and consequences of larval dispersal
Jeff Shima ∗ 1, Steve Swearer 2
1Victoria University of Wellington (VUW) – School of Biological Sciences Victoria University Coastal Ecology Lab (VUCEL), New Zealand
2School of BioSciences, University of Melbourne (UniMelb) – Parkville Campus Victoria, Australia 3010, Australia
Larval dispersal is disproportionately important for marine population ecology and evolu- tion, yet our inability to track individuals severely constrains our understanding of this key process. We analyze otoliths of a temperate reef fish, the common triplefin (Forsterygion lapil- lum), to reconstruct individual dispersal histories and address the following questions: (1) How many discrete sets of dispersal histories (‘dispersal cohorts’) contribute to replenishment of fo- cal populations; (2) When do dispersal cohorts converge (a metric of shared dispersal histories among cohorts); and (3) Do these patterns predict spatio-temporal variation in larval supply?
We used light traps to quantify larval supply, and otolith microstructure and microchemistry (using LA-ICP-MS) to reconstruct daily environmental histories of individuals in their 30-day lead-up to settlement. Our results indicate a variable number of dispersal cohorts replenish fo- cal populations (range: 2-8, mean=4.3, SD=2.8). Convergence times varied (from 0d to >30d prior to settlement), and larval supply was negatively correlated with cohort evenness but not with the number of cohorts, or when they converged-indicating disproportionately large contri- butions from some cohorts (i.e., sweepstakes events).Collectively, our results suggest that larval reef fishes may variably disperse in shoals, to drive local replenishment and connectivity within a metapopulation.
∗Speaker
Weak and monthly variable self-recruitment in the coral reef damselfish Dascyllus
aruanus in New Caledonia
C´ ecile Fauvelot ∗ 1, Marion Cuif 1,2, David Kaplan 2,3, Daphne Grulois 1, Laurent Vigliola 1, Tri Nguyen-Huu 2, Christophe Lett 2
1Ecologie marine tropicale des oc´eans Pacifique et Indien (ENTROPIE [Nouvelle-Cal´edonie]) – 101 avenue Roger Laroque, BP A5, 98848 Noum´ea, New Caledonia, New Caledonia
2 Unit´e de mod´elisation math´ematique et informatique des syst`emes complexes [Bondy] (UMMISCO) – Universit´e Pierre et Marie Curie - Paris 6, Institut de Recherche pour le D´eveloppement - IRD (FRANCE) – Centre de Recherche Halieutique M´editerran´eenne et Tropicale, Avenue Jean Monnet, CS
30171, 34203 S`ete Cedex, France, France
3 Virginia Institute of Marine Science – Virginia Institute of Marine Science, College of William Mary, P.O. Box 1346, 1375 GreateRoad, Gloucester Point, Virginia 23062-1346, USA, United States
Understanding the dynamics of marine populations is critical to managing marine systems effectively, and requires information on patterns of population dispersal and connectivity that are still poorly known. Here we use three complementary approaches to study larval dispersal of the Humbug damselfish,Dascyllus aruanus, in the patchy reefs seascape of the South-West Lagoon of New Caledonia (SWL), South-West Tropical Pacific. We used i) transgenerational marking (TRAIL) and ii) parentage analysis based on 10 microsatellite to assess self-recruitment empir- ically on a reef of the lagoon, as well as connectivity between this focal reef and 10 surrounding reefs. Lastly, iii) a biophysical model was developed to simulate larval trajectories during their dispersal phase within the lagoon. Both empirical methods revealed that self-recruitment var- ied significantly between months (ranging from 0 to 68 %) but was generally low. However, we found that the threshold used to determine marked/assigned individuals significantly affects perceived self-recruitment and connectivity rates and, therefore, must be chosen very carefully.
To consolidate this result, we developed a new method to quantify the uncertainty associated with empirical estimates of connectivity. With this new approach we could estimate a 95% confi- dence interval of 0–3 true parent-offspring pairs and 7–23 TRAIL-marked settlers. In agreement with our empirical results, simulated self-recruitment at the focal reef and connectivity with the surrounding reefs exhibited considerable temporal variability and was generally very low, with an average value of ˜ 0.1 % (range 0–1%). In conclusion, self-recruitment on a focal reef of the South lagoon of New-Caledonia and connectivity with the surrounding reefs is possible but generally very low, which contrasts with results reported before in similar studies, though on different location. As other comparable studies start to accumulate, determining the physical,
C7/ Larval recruitment in marine and freshwater fishes: Current issues
and future directions
Are mangroves important for reef fish on the Island of Mayotte in the Indian Ocean?
Rakamaly Madi Moussa ∗ 1
1 Institute for Pacific Coral Reefs (IRCP) – BP 1013 Papetoai 98729 Moorea, Polyn´esie fácaise Tel : (689) 40 56 13 45, French Polynesia
Coastal habitats such as mangroves are widely considered important nursery grounds for various species of juvenile reef fishes. In the Caribbean, mangroves are clearly connected to coral reef, while the function of Indo-pacific mangroves as nursery habitats for reef fishes has long been debated. This ecosystem has unfortunately been affected by human activity such as coastal development, bush clearance, landfill and unsustainable fishing. Due to a lack of studies, the nursery role of these habitats in this region remains undetermined and it is, therefore, essential to understand the role played by mangroves for coral reef fish on Mayotte Island. Sampling was carried out during twelve months from April 2016 to March 2017 in three sites (Bandrele near to a fringing reef, Dzoumogne close to a river mouth and Malamani in a bay) on the mangrove front using a fyke net combined to visual census surveys. A total of 28,689 fishes distributed among 75 species were recorded. The catches indicate the abundance of juveniles or sub-adults and small- sized species. At Bandrele’s site, specie richness was more diverse than the two other sites with more reef fish species, indicating that proximity to the coral reef provide an important habitat for juveniles reef fishes. Ambassidae, Atherinidae, Mugilidae, Sillaginidae, and Mullidae were the most abundant families in the mangrove of Dzoumogne whereas Atherinidae, Ambassidae and Leiognathidae dominated the fish population in Malamani Bay. We assume that the habitat configuration of the Bandrele site shows a possible effect of habitat connectivity between coral reef fish and adjacent mangroves. The mangroves of Mayotte also provide an additional foraging area for adults reef fish species during high tide. The mangroves are important habitats for a diverse assemblage of fish and also have a nursery function. However the mangrove importance to Mayotte’s reef fish is limited and its role as a nursery for juvenile reef fish should not be generalised to the whole mangrove island.
Artificial Light At Night in the Underwater World
Jack O’connor ∗ 1, Emily Fobert 1, Marc Besson 2, Lecchini David 2
1University of Melbourne – Melbourne, Australia
2 CRIOBE – bp 1013 Papetoai, French Polynesia
Anthropogenic light pollution affects organisms in terrestrial ecosystems, with chronic expo- sure leading to altered behaviours and community structures. Although over 20% of the world’s populated coastline experiences light pollution from coastal infrastructure and marine vessels, we know little about its impacts on marine organisms, many of which rely on natural lunar cues to trigger critical biological functions. We investigated for the first time the effects of artificial light on coral reef fishes during their early life history . Experiments on habitat choice, endocrinology, histology, growth and predation showed that individuals were behaviourally and physiologically sensitive to artificial light exposure from the larval stage through to post-settlement, result- ing in higher mortality rates and predation vulnerability. These results suggest that increasing exposure to coastal lighting may impact coral-reef fish populations.
∗Speaker
Effect of the 2011 Tsunami disaster accompanying the Great East Japan Earthquake on the population dynamics of
Japanese tube snout Aulichthys japonicus
Go Katayose ∗† 1, Takashi Asahida‡ 1
1School of Marine Biosciences, Kitasato University – Kitasato, Sagamihara, Kanagawa 252-0373, Japan
The Japanese tube snoutAulichthys japonicus is a small fish species which lives in shallow coastal waters, especially in seagrass (Zostera spp.) beds. The fish is known for their unusual spawning behavior of concealing their eggs in ascidians (Halocynthia roretzi). We have been studying the larval and juvenile fish fauna in a seagrass bed in southern Iwate, Japan from 2007, and observed that the fish is a dominant species in the seagrass bed. On March 11, 2011, the seagrass bed was washed away by the Tsunami. The Japanese tube snout also decreased after the Tsunami disaster together with the loss of the seagrass bed which plays an important role as a nursery ground for various coastal fishes. The seagrass bed has been recovering since 2012, the number of tube snout has also increased from 0.080 /m2 in 2012 to 0.214 /m2 in 2013.
In contrast, the number decreased to 0.050 /m2 in 2014. We assumed that the increase and decrease of ascidian individuals affected the number of tube snouts, we counted the number of individuals of ascidians growing on the seawall adjacent to the seagrass bed. The number of ascidians increased from 0 /m2 in just after the Tsunami (2011) to 10 /m2 in 2013, however, they decreased to 8 /m2 in the spring of 2014 due to human activity. In 2015, all of the ascidians on the seawall were scraped off due to reconstruction, and the tube snout decreased to 0.048 /m2 in 2016 even though the seagrass bed has recovered. We observed some egg masses of the tube snout in the removed ascidians collected from the sea bed. The results of a statistical analysis using model selection by AIC suggested the effects of the decrease of ascidians led to the decrease of the tube snout.
Environmental effects on larval swimming performance in Amphiprion chrysopterus
Daphne Cortese ∗† 1, Zoe Scholz 1, Suzanne Mills 1, Tommy Norin 2, Shaun Killen 2, Ricardo Beldade 1
1 Centre de recherches insulaires et observatoire de l´environnement (CRIOBE) – BP 1013 Papetoiai 98729 PAPETOAI, French Polynesia
2 University of Glasgow – Institute of Biodiversity, Animal Health Comparative Medicine, Glasgow, G12 8QQ, United Kingdom
Over the last few decades environmental changes have become more intense and frequent with considerable impacts on coral reef ecosystems. One way in which organisms can cope with these global changes is by shifting their range of distribution, which in most fish depends on their pelagic larval phase. The ability to disperse depends on certain phenotypic larval traits, which are plastic, but whether these traits depend on the parental phenotypic traits and/or the environmental context (water currents) from which larvae originate, is not yet clear. Here, we test the hypothesis that coral reef fish larval traits associated to dispersal (total length, pectoral and caudal fin size, as well as critical swimming speed - Ucrit) depend on the environment (i.e.
water currents) and on parental phenotypic traits. Using offspring from breeding orange-fin anemonefish (Amphiprion chrysopterus): firstly we show the great variability in larval traits associated to dispersal within and among families; secondly, morphological traits associated to dispersal are not heritable; thirdly, larval swimming speed (Ucrit) depends on parental origin, and finally we show that environmental variability has an effect on larval phenotypes, particularly on larval size and Ucrit. From the moment of hatching until settlement, larvae with better swimming performance should also be better able to disperse and/or find a suitable settlement habitat. The specific way in which these traits influence the final dispersal and settlement outcomes remains unanswered.
∗Speaker
†Corresponding author: daph.cortese@gmail.com
Fish sampling like nowhere else: remote video methods for studying fish populations in a croc infested, turbid, macrotidal system
Camilla Piggott ∗ 2,1, Martial Depczynski 2, Timothy Langlois 3
2 Australian Institute of Marine Science (AIMS Perth) – Indian Ocean Marine Research Centre, Level 3 The University of Western Australia Fairway Crawley, WA 6009, Australia
1 University of Western Australia (UWA) – 35 Stirling Hwy, Crawley WA 6009, Australia
3 University of Western Australia (UWA) – 35 Stirling Hwy, Crawley WA 6009, Australia
Macrotidal and highly turbid environments present significant logistical and methodological challenges for research scientists. When coupled with factors such as remoteness, inaccessibility and an abundance of salt water crocodiles (Crocodylus porosus) the ability to reliably collect fish community data using established diver visual sampling methods can be compromised.
Understanding which data collection methods work best is therefore critical to provide a realis- tic ecological picture through the minimisation of extraneous variability. Baited and unbaited remote underwater video ([B]RUVs) sampling is being increasingly used to sample adult fish populations, typically for information on species composition and distribution, relative abun- dance, and size. [B]RUVs have been found to be cost-effective across a broad range of habitats and depths however they have not previously been used in macrotidal low visibility environ- ments to sample juvenile fish. This study was conducted in the Kimberley region of northwest Australia; an ecosystem that experiences tidal forcing of up to 10 knots, has a tidal range of 12 metres and ubiquitous poor water visibility. Both BRUVs and RUVs were deployed in a range of habitats, tidal states, current strengths and levels of turbidity to determine how each of these influenced the collection of relative abundance, richness and size data for adult and juvenile fish.
Gaining the competitive edge: is early life-history linked to post-settlement performance in a territorial reef fish?
Emily Fobert ∗ 1, Davina Poulos 2
1University of Melbourne – Melbourne, Australia
2 James Cook University (JCU) – Townsville, Australia
Research on early life-histories of marine reef fishes has determined that patterns of recruit- ment and survival in the post-settlement stage are largely established in the dispersal phase, as larval experience during dispersal can significantly influence individual fitness and habitat choice at settlement, and early post-settlement survival. Despite significant advancements in understanding the link between early life-history and post-settlement success in reef fishes, few studies have linked larval growth histories to behavioural traits and social interactions in the post-settlement stage. This is a critical question as the outcome of competitive interactions will influence the success of an individual through increased or reduced access to resources. In this study, we used a manipulative field experiment to investigate whether a physical advan- tage in the larval stage is linked to advantageous post-settlement behaviour (aggression and dominance) in a territorial damselfish, Pomacentrus amboinensis. Larval P. amboinensis were collected from light traps off Lizard Island, Australia. Fish were tagged and released onto exper- imental patch reefs, and boldness and aggression displays were monitored to assign a dominance hierarchy. Following the experiment, larval growth histories were calculated from the dispersal period of individual otoliths, to determine if there is a relationship between early life-history and competitive dominance in the post-settlement environment.
∗Speaker
Importance of metamorphosis in coral reef fish larval recruitment facing global change
and water pollution
Marc Besson ∗† 1, David Lecchini 1, Guillaume Holzer 2, Loăıc Franácois 1, Isadora Moniz 1, Hugo Jacob 1, Pauline Salis 3, Vincent Laudet 3
1 PSL Research University - EPHE-CNRS-UPVD USR3278 CRIOBE – BP1013 Papetoai, 98729 Moorea, French Polynesia
2 IGFL, UMR CNRS 5242, ENS Lyon – ´Ecole normale sup´erieure - Lyon, ´Ecole Normale Sup´erieure - Lyon – 46 All´ee d’Italie, 69364 Lyon Cedex 07, France
3 OOB, UMR CNRS 7232 BIOM UPMC – oob – 1 avenue Pierre Fabre, 66650 Banyuls-sur-Mer, France
Life history transitions are critical for many animal species and often correspond to con- comitant developmental and ecological shifts. Unfortunately, little is known on how internal and external cues act in concert during these events. Most teleost reef fish life cycle includes a major developmental and ecological transition. Adults reproduce in the vicinity of the reef, emitting eggs that disperse and hatch in the ocean, where the larvae grow. Then, larvae migrate back towards reefs where they settle and persist, a step called larval recruitment. Larval recruit- ment involves the perception of environmental cues for larvae to localize and select their new benthic habitat, and is accompanied by major morphological changes. Therefore, this ecological and developmental transition of pelagic larvae into reef-associated juveniles is often referred to as metamorphosis. This step is critical for the maintenance of reef fish populations, but its molecular control remains largely unknown.
In the current context of worldwide degradation of coral reef ecosystems, what affect coral reef fish populations and assemblages is no longer only attributed to overfishing pressures but also to replenishment issues. Indeed, the loss and degradation of coral habitats has been ac- knowledged for years to reduce (i) the potential of reefs to attract coral reef fish young settlers and (ii) the survival of these settlers. This leads to dramatic failure in larval recruitment and subsequent population replenishment in degraded reef areas.
Here, I will present new insights on coral reef fish metamorphosis: a TH regulated process reminiscent of the situation in amphibians that is at the crossroad of ecological, developmental, physiological and behavioral transformations, and which is prone to endocrine disruption. Since metamorphosis and larval recruitment are essential for the maintenance of fish populations and subsequent coral reef resilience, this provides a general framework to better understand, at the