Adult Habitat Research Articles

Climate change decouples marine and freshwater habitats of a threatened migratory fish

AbstractAimTo assess how climate change may decouple the ecosystems used by a migratory fish, and how decoupling influences priorities for stream restoration.LocationAustralia.MethodsWe modelled changes in habitat suitability under climate change in both riverine and marine habitats for a threatened diadromous species, the Australian Grayling Prototroctes maraena, using niche models. The loss of riverine habitats for Grayling was compared with or without considering the impact of climate change on adjacent marine habitats. We also asked whether considering marine climate change changed the locations where removing dams had the greatest benefit for Grayling conservation.ResultsClimate change is expected to cause local extinction in both marine and river habitats regardless of whether dams are retained or removed at the trailing edge of the Grayling's range (north‐eastern). Decoupling of habitats was most apparent in the eastern and south‐eastern portion of the Grayling's range, where ocean warming may cause a decline in the suitability of marine habitats for larvae, while many freshwater habitats retained suitable habitat for adults. Removing dams to restore connectivity between ocean and freshwater habitats was predicted to have the greatest benefit for Grayling in southern portions of their range. Under climate change, the priorities for barrier removal gradually shift towards dams at higher elevation because of increasing suitability of freshwater habitats at higher elevations.Main conclusionsOur study highlights the importance of assessing climate range shifts in multiple ecosystems for migratory species and can help inform priorities for stream restoration under a changing climate.

The relative influence of temperature and size‐structure on fish distribution shifts: A case‐study on Walleye pollock in the Bering Sea

AbstractResearch has estimated associations between water temperature and the spatial distribution of marine fishes based upon correlations between temperature and the centroid of fish distribution (centre of gravity, COG). Analysts have then projected future water temperatures to forecast shifts in COG, but often neglected to demonstrate that temperature explains a substantial portion of historical distribution shifts. We argue that estimating the proportion of observed distributional shifts that can be attributed to temperature vs. other factors is a critical first step in forecasting future changes. We illustrate this approach using Gadus chalcogrammus (Walleye pollock) in the Eastern Bering Sea, and use a vector‐autoregressive spatiotemporal model to attribute variation in COG from 1982 to 2015 to three factors: local or regional changes in surface and bottom temperature (“temperature effects”), fluctuations in size‐structure that cause COG to be skewed towards juvenile or adult habitats (“size‐structured effects”) or otherwise unexplained spatiotemporal variation in distribution (“unexplained effects”). We find that the majority of variation in COG (including the north‐west trend since 1982) is largely unexplained by temperature or size‐structured effects. Temperature alone generates a small portion of primarily north–south variation in COG, while size‐structured effects generate a small portion of east–west variation. We therefore conclude that projections of future distribution based on temperature alone are likely to miss a substantial portion of both the interannual variation and interdecadal trends in COG for this species. More generally, we suggest that decomposing variation in COG into multiple causal factors is a vital first step for projecting likely impacts of temperature change.

Speyeria (Lepidoptera: Nymphalidae) Conservation.

Speyeria (Nymphalidae) are a conspicuous component of the North American butterfly fauna. There are approximately 16 species and >100 associated subspecies (or geographical variants). Speyeria are univoltine, occupy a wide range of habitats, overwinter as first instar larvae, and feed only on native violets. Speyeria species have become a model group for studies of evolution, speciation, and conservation. Several species and subspecies are threatened or endangered. The reasons for this vary with the taxa involved, but always involve the degradation or loss of quality habitat for larvae and adults. The impacts of climate change must be considered among the causes for habitat degradation and in the establishment of conservation measures. In addition to increasing the available habitat, conservation efforts should consider maintaining habitat in a seral “disturbed” successional stage that selectively favors the growth of violets and preferred adult nectar sources. A major future challenge will be determining the most effective allocation of conservation resources to those species and subspecies that have the greatest potential to respond favorably to these efforts.

Selecting habitat to what purpose? The advantage of exploring the habitat–fitness relationship

AbstractMeasures of reproductive success have been recognized in many fields as essential tools to assess the status of populations, species, and communities. However, difficulties in gathering data on reproductive success often prevent researchers from taking advantage of the information offered by those measures. For example, most of habitat selection studies do not include reproductive success in their analysis even though doing so would highly improve our understanding of the habitat selection process. In our study, we aimed to assess to what extent habitat selection choices made by adult individuals are directed to increase their annual reproductive success. We tested this idea by first developing habitat selection models and then relating the results of those models to two measures of reproductive success. Using wolves, Canis lupus, as the study species, we determined that not all habitat selection choices performed by adult wolves were related to their annual reproductive success. The results varied also in relation to the measure of reproductive success used in the analysis and other individual‐, group‐, and population‐level factors. Likely, adult female wolves select habitat characteristics to increase not only their annual reproductive success but also their lifetime reproductive success, for example, by ensuring their own survival and reproductive abilities in subsequent years. Our study suggests that a variety of motivations may govern habitat choices performed by adult individuals and including different measures of fitness in habitat selection studies can improve our understanding of these complex processes.

Duckling survival of mallards in Southland, New Zealand

ABSTRACTThe southern portion of New Zealand's South Island is a productive area for mallards (Anas platyrhynchos) despite a notable lack of permanent or semi‐permanent wetlands. Most broods are reared in pastures that may or may not be flooded with ephemeral water. In recent years, there has been an increased conversion from continuous to sporadic grazing that has resulted in a functional change in the emergent and upland vegetation available for broods. In 2014, we investigated mallard duckling survival on different pastures relative to a suite of characteristics pertaining to the adult female, clutch, brood, weather, and habitat. We monitored 438 ducklings from 50 radio‐marked females to 30 days post‐hatch. Duckling survival was unaffected by pasture type but increased with duckling age, the presence of ephemeral water, and with greater distance from the nearest anthropogenic structure. Survival was lower for broods of second year (SY) females than for broods of after‐second year (ASY) females, in areas with more dense cover, and when ducklings moved, on average, greater daily distances. Cumulative 30‐day duckling survival ranged from 0.11 for ducklings of SY females without ephemeral water present to 0.46 for ducklings of ASY females with ephemeral water present. Therefore, increasing available seasonal water sources may increase duckling survival. Further, narrow, linear patches of dense cover present in our study could support a greater abundance of predators or increase their foraging efficiency. As such, managers could consider increasing patch sizes of dense cover to reduce predator efficiency, and employing predator removal in these areas to improve duckling survival. © 2017 The Wildlife Society.

Spatiotemporal Reproduction and Larval Habitat Associations of Nonnative Silver Carp and Bighead Carp

AbstractThe establishment of nonnative Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (collectively referred to as “bigheaded carp”) in the central United States may have negative ecological consequences and economic impacts. Our objectives were to quantify patterns and habitat associations of adult bigheaded carp reproduction, larval production, and habitat use; such information is important for control strategies and identifying recruitment sources. During May–August 2011, we sampled adults and larvae at 10 sites distributed adjacent to and within the main channel of the Mississippi River at Pool 26 (study area = 28 river kilometers). Female reproductive status, adult location, and larval density were compared to environmental conditions, including temperature, site velocity, and turbidity. Large females spawned earlier than their smaller counterparts. No clear spawning aggregations of adults were observed, suggesting plasticity in staging habitat. Larvae were distributed across all sites during flooding. Larval density was positively related to velocity and turbidity, suggesting that nondepositional areas may facilitate recruitment. Bigheaded carp larvae comprised 10% of the ichthyofauna. Although pooled reaches are a source of recruitment for bigheaded carp in the Mississippi River system, the low densities of bigheaded carp larvae relative to native larvae cannot explain the dominance of adults in this system. Our findings provide insights into the plastic nature of bigheaded carp reproduction and habitats associated with larval development. Control efforts that target large adult females should be conducted earlier during the spring spawn. To maintain fishing pressure, such control efforts would likely need to continue through the summer, when smaller individuals spawn, discharge decreases, and CPUE increases. However, we found no specific mass staging area or habitat type where adult females could be targeted.Received July 19, 2016; accepted December 14, 2016 Published online March 21, 2017

Seasonal Variability In Subtidal Fish Assemblages Inhabiting Sandy-Bottom Habitats Off Humboldt Bay, California

Abstract This study documents the seasonal fine-scale distribution, species richness, and abundance of subtidal fish species inhabiting sandy-bottom habitats in areas adjacent to Humboldt Bay, California. In total, 3 sampling areas, 2 located 5-km offshore, and 1 located 1-km offshore, were sampled quarterly for 1 y. Flatfish species (families Pleuronectidae and Bothidae) were the most common finfish sampled, although seasonal and spatial patterns varied among individual species. For instance, the abundance and size of English Sole (Parophrys vetulus) and Pacific Sanddab (Citharichthys sordidus) varied across both seasons and sampling areas, which may be attributed to their ontogenetic migration to offshore adult habitat. Species such as Starry Flounder (Platichthys stellatus) and Butter Sole (Isopsetta isolepis), did not vary seasonally, but did differ across sampling areas, likely as a function of depth. Although not the primary focus of our study, we include the abundance and diversity of invertebrates...

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds.

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival.

Characterization of Depth Distributions, Temperature Associations, and Seasonal Migrations of Atlantic Halibut in the Gulf of St. Lawrence using Pop‐Up Satellite Archival Tags

AbstractThe fishery for Atlantic Halibut Hippoglossus hippoglossus in the Gulf of St. Lawrence (Gulf) is currently experiencing its highest landings since the 1950s. However, the absence of information on adult habitat use has limited the development of new survey methodologies. The aim of this study was to use pop‐up satellite archival tags on large (≥108‐cm) halibut in the Gulf to provide data on seasonal temperature associations, depth distributions, and migrations. Twenty Atlantic Halibut were tagged in 2013 and 15 were tagged in 2015 at two different locations in the northern Gulf. Atlantic Halibut overwintered in the central and northern Gulf based on six tag pop‐offs. In the winter in both studies, halibut were distributed at 160–440 m depth with a narrow temperature association of 5.5–6.5°C, which corresponded with the bathymetry and hydrography of the Gulf rather than the deeper and colder waters of the continental shelf where the southern stock occurs. Spawning rises were identified from the depth data for two halibut in 2013 and six halibut in 2015. In the summer, halibut had a wide range of depth (20–200 m) and temperature (−1.5°C to +15.0°C) associations, and tag pop‐offs in August indicated feeding grounds off the northwestern coast of Newfoundland. There was a broad geographic distribution of final pop‐offs in 2013, but in 2015 all tags popped off close (<55 km) to the original tagging site. These seasonal depth distributions and temperature associations will be used to inform Atlantic Halibut stock assessments and management decisions.

First data on Sciomyzidae (Diptera) of Iturup Island (Kuril Islands)

The first data are presented about the Sciomyzidae of Iturup, the largest of the Kuril Islands. A total of ten species are recorded. Limnia setosa Yano is recorded for the first time from Russia; Tetanocera montana Day and T. phyllophora Melander are recorded for the first time from the Kuril Islands. Photographs, comments on diagnostic characters and adult habitats of poorly known species are given.

Comparison of West Balkan adult trout habitat predictions using a Pseudo-2D and a 2D hydrodynamic model

Abstract Hydraulic-habitat models combine the dynamic behavior of river discharge with geomorphological and ecological responses. In this study, they are used for estimating environmental flow requirements. We applied a Pseudo-two-dimensional (2D) model based on the one-dimensional (1D) HEC-RAS model and an in-house 2D (FLOW-R2D) hydrodynamic model to a section of river for several flows in respect of summer conditions of the study reach, and compared the results derived from the models in terms of water depths and velocities as well as habitat predictions in terms of weighted usable area (WUA). In general, 2D models are more promising in habitat studies since they quantify spatial variations and combinations of flow patterns important to stream flora and fauna in a higher detail than the 1D models. Relationships between WUA and discharge for the two models were examined, to compare the similarity as well as the magnitude of predictions over the modelled discharge range. The models predicted differences in the location of maxima and changes in variation of velocity and water depth. Finally, differences in spatial distribution (in terms of suitability indices and WUA) between the Pseudo-2D and the fully 2D modelling results can be considerable on a cell-by-cell basis.

High Interannual Variability in Connectivity and Genetic Pool of a Temperate Clingfish Matches Oceanographic Transport Predictions.

Adults of most marine benthic and demersal fish are site-attached, with the dispersal of their larval stages ensuring connectivity among populations. In this study we aimed to infer spatial and temporal variation in population connectivity and dispersal of a marine fish species, using genetic tools and comparing these with oceanographic transport. We focused on an intertidal rocky reef fish species, the shore clingfish Lepadogaster lepadogaster, along the southwest Iberian Peninsula, in 2011 and 2012. We predicted high levels of self-recruitment and distinct populations, due to short pelagic larval duration and because all its developmental stages have previously been found near adult habitats. Genetic analyses based on microsatellites countered our prediction and a biophysical dispersal model showed that oceanographic transport was a good explanation for the patterns observed. Adult sub-populations separated by up to 300 km of coastline displayed no genetic differentiation, revealing a single connected population with larvae potentially dispersing long distances over hundreds of km. Despite this, parentage analysis performed on recruits from one focal site within the Marine Park of Arrábida (Portugal), revealed self-recruitment levels of 2.5% and 7.7% in 2011 and 2012, respectively, suggesting that both long- and short-distance dispersal play an important role in the replenishment of these populations. Population differentiation and patterns of dispersal, which were highly variable between years, could be linked to the variability inherent in local oceanographic processes. Overall, our measures of connectivity based on genetic and oceanographic data highlight the relevance of long-distance dispersal in determining the degree of connectivity, even in species with short pelagic larval durations.

Siting marine protected areas based on habitat quality and extent provides the greatest benefit to spatially structured metapopulations

AbstractConnectivity and its role in the persistence and sustainability of marine metapopulations are attracting increased attention from the scientific community and coastal resource managers. Whether protection should prioritize the connectivity structure or demographic characteristics of a given patch is still unclear. We design a three‐stage population model to analyze the relative importance of sources, sinks, quality and extent of juvenile and adult habitat, and node centralities (eigenvector, degree, closeness, and betweenness) as a basis for prioritizing sites. We use a logistic‐type stage‐structured model to describe the local dynamics of a population with a sessile adult stage and network models to elucidate propagule‐exchange dynamics. Our results show that the coupled states of habitat extent and quality, which determine population carrying capacity, are good criteria for protection strategy. Protecting sites on the basis of sources, sinks, or other centrality measures of connectivity becomes optimal only in limited situations, that is, when larval production is not dependent on the adult population. Our findings are robust to a diverse set of larval pathway structures and levels of larval retention, which indicates that the network topology may not be as important as carrying capacity in determining the fate of the metapopulation. Protecting extensive, good quality habitat can help achieve both conservation and fisheries objectives.

Impact of Highland Topography Changes on Exposure to Malaria Vectors and Immunity in Western Kenya.

It is almost an axiom that in the African highlands (above 1,500 m) transmission of Plasmodium falciparum is limited primarily by low ambient temperature and that small changes in temperature could result in temporary favorable conditions for unstable transmission within populations that have acquired little functional immunity. The pattern of malaria transmission in the highland plateau ecosystems is less distinct due to the flat topography and diffuse hydrology resulting from numerous streams. The non-homogeneous distribution of larval breeding habitats in east African highlands obviously affects Anopheles spatial distribution which, consequently, leads to heterogeneous human exposure to malaria. Another delicate parameter in the fragile transmission risk of malaria in the highlands is the rapid loss of primary forest due to subsistence agriculture. The implication of this change in land cover on malaria transmission is that deforestation can lead to changes in microclimate of both adult and larval habitats hence increase larvae survival, population density, and gametocytes development in adult mosquitoes. Deforestation has been documented to enhancing vectorial capacity of Anopheles gambiae by nearly 100% compared to forested areas. The study was conducted in five different ecosystems in the western Kenya highlands, two U-shaped valleys (Iguhu, Emutete), two V-shaped valleys (Marani, Fort Ternan), and one plateau (Shikondi) for 16 months among 6- to 15-year-old children. Exposure to malaria was tested using circumsporozoite protein (CSP) and merozoite surface protein immunochromatographic antibody tests. Malaria parasite was examined using different tools, which include microscopy based on blood smears, rapid diagnostic test based on HRP 2 proteins, and serology based on human immune response to parasite and vector antigens have been also examined in the highlands in comparison with different topographical systems of western Kenya. The results suggested that changes in the topography had implication on transmission in highlands of western Kenya and appropriate diagnosis, treatment, and control tool needed to be considered accordingly. Both plateau and U-shaped valley found to have higher parasite density than V-shaped valley. People in V-valley were less immune than in plateau and U-valley residents. Topography diversity in western Kenya highlands has a significant impact on exposure rates of human to malaria vectors and parasite. The residents of V-shaped valleys are at risk of having explosive malaria outbreaks during hyper-transmission periods due to low exposure to malaria parasite; hence, they have low immune response to malaria, while the U-shaped valleys have stable malaria transmission, therefore, the human population has developed immunity to malaria due to continuous exposure to malaria.

Surfzone hydrodynamics as a key determinant of spatial variation in rocky intertidal communities.

Larvae of intertidal species develop at sea and must return to adult habitats to replenish populations. Similarly, nutrients, detritus and plankton provide important subsidies spurring growth and reproduction of macroalgae and filter-feeding invertebrates that form the foundation of intertidal communities. Together, these factors determine the density and intensity of interactions among community members. We hypothesized that spatial variation in surfzone hydrodynamics affects the delivery of plankton subsidies. We compared entire zooplankton communities inside and outside the surf zone daily while monitoring physical conditions for one month each at two shores with different surfzone characteristics. Opposite cross-shore distributions of larvae and other zooplankters occurred at the two sites: zooplankton was much more abundant inside the mildly sloping dissipative surf zone (DSZ) with rip currents and was more abundant outside the steep reflective surf zone (RSZ). Biophysical numerical simulations demonstrated that zooplankters were concentrated in rip channels of the DSZ and were mostly unable to enter the RSZ, indicating the hydrodynamic processes behind the observed spatial variation of zooplankters in the surf zone. Differences in the concentration of larvae and other zooplankters between the inner shelf and surf zone may be an underappreciated, key determinant of spatial variation in inshore communities.

Heterochrony in Two Sculpins of the GenusPsychrolutes: Growth Outpaces Skeletal Development in an Apex Predator among Ichthyoplankton

In fishes, development is a plastic process, even among closely related, sympatric taxa. Selective pressure manifests itself through morphological divergences in early life. Of particular interest in the present study is heterochrony: alterations in developmental rates of change. Examinations of skeletal development in the Soft Sculpin, Psychrolutes sigalutes, and Tadpole Sculpin, Psychrolutes paradoxus, revealed marked developmental differences between species. While P. paradoxus quickly develops an adult skeleton and settles in adult habitat, P. sigalutes undergoes a remarkably protracted transformation (the transition from larval to juvenile characters) over a period of three to four months. It reaches sizes in excess of 40 mm (75% of adult size) before settling. While the earliest phases of life focus on the development of feeding elements and a transition from larval/anguilliform locomotion to caudal/subcarangiform propulsion, the two species diverge quickly in postflexion development. With the excep...

Habitat characteristics of breeding Eurasian Whimbrel Numenius phaeopus on Mainland Shetland, Scotland, UK

ABSTRACTCapsule: Habitats used by Whimbrel Numenius phaeopus chicks for feeding are significantly different to those used by adults for feeding and nesting.Aim: To identify habitats used by breeding Whimbrel on Mainland Shetland.Methods: Fourteen study sites were used to identify three main components of Whimbrel breeding habitats: (i) adult territorial and foraging habitats; (ii) nest site habitats; (iii) chick feeding habitats. The relationship between these components was investigated using principal components analysis.Results: Habitats used by adults comprised blanket bog dominated by ling heather, cross-leaved heath, common cottongrass, hare’s-tail cottongrass, deergrass and purple moor-grass. There was a thick layer of bryophytes but few forbs. Habitat used for nesting was similar to the general habitat used by adults. The habitats in which Whimbrel chicks foraged were significantly different in structure from the habitats used by adults. The chick feeding areas were characterized by small, wet and often linear features.Conclusion: Habitat requirements by Whimbrel chicks for foraging differed from those of adult Whimbrel for nesting. Habitat structure is important for chicks and the presence of small, wet linear features may be a limiting component on otherwise apparently suitable adult Whimbrel habitats.

Population biology and recruitment of a vulnerable sea cucumber, Stichopus herrmanni, on a protected reef

AbstractPopulations of tropical sea cucumbers, harvested for bêche‐de‐mer, are in a perilous state of conservation, yet there remains a paucity of information on the biology of many harvested species. We examined the population biology of the commercially important curryfish, Stichopus herrmanni, across 2 years on Heron Reef, a protected zone in the Great Barrier Reef (GBR) Marine Park. Stichopus herrmanni, a species recently listed as vulnerable to extinction, is a major target species for the fishery operating in the GBR. The size class distribution and density of S. herrmanni were documented for six sites across Heron Reef. There was distinct spatial variation in the size and density of S. herrmanni across sites, with no significant difference between the 2 years. The smallest individuals found were 10 cm long, some of the only juvenile S. herrmanni documented in nature. Juvenile and sub‐adult populations were found along the leeward reef edge of Heron Reef, a habitat characterized by shallow channels of sand between inter‐tidal coral reef and crustose coralline algae (CCA). Juvenile nurseries of sea cucumbers are rarely observed in nature, making this an important observation for understanding the recruitment and population biology of S. herrmanni. The presence of juveniles in the consolidated CCA habitat each year in autumn following the summer spawning period, and the absence of small individuals several months later in spring, suggests an ontogenetic migration or displacement of these individuals to adult habitat. The distribution of larger S. herrmanni suggests intra‐reef connectivity and migration into deeper lagoon areas. This study contributes to understanding the population dynamics of this vulnerable species, a consideration for fisheries management in light of increasing global harvest.

Complex post-larval dispersal processes in Atlantic cod revealed by age-based genetics and relatedness analysis

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 556:237-250 (2016) - DOI: https://doi.org/10.3354/meps11819 Complex post-larval dispersal processes in Atlantic cod revealed by age-based genetics and relatedness analysis John B. Horne1,*, Ian R. Bradbury2, Ian G. Paterson1, David Hardie3, Jeffrey Hutchings1,4, Benjamin J. Laurel5, Paul V. R. Snelgrove6, Corey J. Morris2, Robert S. Gregory2, Paul Bentzen1 1Marine Gene Probe Laboratory, Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, NS B3H 4R2, Canada 2Department of Fisheries and Oceans Canada, 80 E. White Hills Road, St. John’s, NL A1C 5X1, Canada 3Department of Fisheries and Oceans Canada, Dartmouth, NS B2Y 4T3, Canada 4Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo 0316, Norway 5Fisheries Behavioral Ecology Program, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Hatfield Marine Science Center, Newport, OR 97365, USA 6Department of Ocean Sciences and Biology Department, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada *Corresponding author: john.horne@gmail.com ABSTRACT: Population connectivity among adult marine organisms is often attributed to dispersal during the egg/larval stage. However, post-larval dispersal may also influence connectivity, particularly when juvenile nursery habitats are separated from adult spawning habitats. Here we used age-based population genetics and kinship analysis to explore changes in population connectivity across life-history stages in Atlantic cod Gadus morhua. We genotyped 364 adult cod from the northwest Atlantic and 671 age-0 juveniles from 18 sites around eastern Newfoundland, with 72 and 15 microsatellite loci, respectively. Adult cod genotypes exhibited more population structure than was detected in juveniles across similar spatial scales. Both age classes had similar allelic diversities, but juveniles exhibited less genetic linkage and fewer departures from Hardy-Weinberg expectations than adults at the same loci. We detected significant kinship relationships in adult cod only within sampling locations, but 1 putative pair of juvenile kin was separated by >500 km. Collections of adults also displayed higher group relatedness compared to juveniles. Genetic differences between age classes are likely due to a combination of non-random mortality and non-random sorting of admixed juveniles into different adult habitats. Many studies overlook post-larval dispersal as a factor of marine population connectivity, but pre-adult relocation may be demographically and adaptively significant, in cod and other species. KEY WORDS: Gadidae · Kinship · Newfoundland · Marine dispersal · Fisheries · Northwest Atlantic Full text in pdf format Supplementary material PreviousNextCite this article as: Horne JB, Bradbury IR, Paterson IG, Hardie D and others (2016) Complex post-larval dispersal processes in Atlantic cod revealed by age-based genetics and relatedness analysis. Mar Ecol Prog Ser 556:237-250. https://doi.org/10.3354/meps11819 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 556. Online publication date: September 08, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Life history, larval dispersal, and connectivity in coral reef fish among the Scattered Islands of the Mozambique Channel

The Western Indian Ocean harbors one of the world’s most diverse marine biota yet is threatened by exploitation with few conservation measures in place. Primary candidates for conservation in the region are the Scattered Islands (Iles Eparses), a group of relatively pristine and uninhabited islands in the Mozambique Channel. However, while optimal conservation strategies depend on the degree of population connectivity among spatially isolated habitats, very few studies have been conducted in the area. Here, we use highly variable microsatellite markers from two damselfishes (Amphiprion akallopisos and Dascyllus trimaculatus) with differing life history traits [pelagic larval duration (PLD), adult habitat] to compare genetic structure and connectivity among these islands using classic population structure indices as well as Bayesian clustering methods. All classical fixation indexes F ST, R ST, G′ST, and Jost’s D show stronger genetic differentiation among islands for A. akallopisos compared to D. trimaculatus, consistent with the former species’ shorter PLD and stronger adult site attachment, which may restrict larval dispersal potential. In agreement with these results, the Bayesian analysis revealed clear genetic differentiation among the islands in A. akallopisos, separating the southern group (Bassas da India and Europa) from the center (Juan de Nova) and northern (Iles Glorieuses) islands, but not for D. trimaculatus. Local oceanographic patterns such as eddies that occur along the Mozambique Channel appear to parallel the results reported for A. akallopisos, but such features seem to have little effect on the genetic differentiation of D. trimaculatus. The contrasting patterns of genetic differentiation between species within the same family highlight the importance of accounting for diverse life history traits when assessing community-wide connectivity, an increasingly common consideration in conservation planning.