Slope Habitats Research Articles

К экологии редких степных видов рода Iris на Южном Урале

The research presents the experience of assessing the diversity of communities and ecology of 3 rare steppe species of the genus Iris L. in the Southern Urals: I. pumila L., I. scariosa Willd. ex Link and I. humilis Georgi which are distributed in the steppe and forest-steppe zones of the region and listed in the Red Data Book of Bashkortostan Republic (Krasnaya kniga…, 2011) and the Russian Federation (Krasnaya kniga…, 2008). We analyzed the ecology of communities with participation of rare species using indirect ordination, which makes it possible to identify important ecological patterns of species distribution and to give an ecological interpretation of syntaxonomic units. Totally, we collected 28 geobotanical releves within the studied coenopopulations in the Southern Urals (mainly, in the Urals and Transurals of the Republic of Bashkortostan, as well as adjacent areas of Chelyabinsk and Orenburg regions) to characterize the phytocenotic localization and ecology of rare steppe species of the genus Iris. Localities of the studied species are presented on the map (See Fig. 1). The size of the releves was 64-100 m2. Releves descriptions and classification were performed using the Braun-Blanquet approach (Westhoff and van der Maarel, 1978; Braun-Blanquet, 1964). The names of vascular plants species are given according to Cherepanov (1995). The impact assessment of complex environmental factor gradients was performed using DCA-ordination in the CANOCO 4.5 program (Ter Braak and Smilauer, 2002). DN Tsyganov’s scale which was adjusted for the Southern Urals region (Shirokikh and Zverev, 2012) was applied to estimate the environmental factors of habitats. The weighted average of environmental factors was calculated in the IBIS software (Zverev, 2007). We revealed that the phytocenosis with participation of rare steppe irises in the Southern Urals belongs to the class Festuco-Brometea Br.-Bl. et Tuxen ex Soo 1947, which unites the steppe vegetation of Southern Ukraine and Russia and includes 5 associations and 2 communities. I. pumila grows mainly on the steppe slopes of various expositions as part of the steppes of association Astragalo austriacae-Stipetum pulcherrimae Martynenko et al. 2018, which is a zonal type of the Pre-Ural steppe of the Republic of Bashkortostan. I. pumila also grows in the communities of the association Scorzonerо austriacaе-Stipetum lessingianae Yamalov 2011 prov., which is steppes with dominating Stipa lessingiana of the southern regions of Bashkortostan and in the basal community Stipa capillata [Festuco-Brometea] combining low-degraded steppe pastures, which are distributed mainly in the upland and slope habitats of the southern expositions. Among the rarest communities with participation of I. рumila, there are phytocoenoses of shrub steppes of association Spiraeo hypericifoliaе-Amygdaletum nanae Solomeshch et al. 1994, which are distributed mainly across the eastern and southeastern slopes of the ranges on stony substrates. I. scariosa was found in the phytocoenosis of the association Silene altaici-Elytrigietum pruiniferae Yamalov 2018 prov., characteristic of outcrops of igneous rocks on thermophilic slopes. Occasionally, I. scariosa is observed in the communities of Festuca pseudovina [ Helictotricho- Stipetalia], distributed to the flattened mountain slopes. Communities with I. humilis occur in the Southern Urals quite rarely and belong, according to their floristic composition, to the association Diantho acicularis-Orostachetum spinosae Schubert et al. 1981. The floristic composition of all noted communities is characterized by a high role of petrophytic species (Artemisia marshalliana, Astragalus helmii, Centaurea turgaica, Ephedra distachya, Hedysarum argyrophyllum, Koeleria sclerophylla, Orostachys spinosa, Tanacetum kittaryanum Thymus guberlinensis etc.). DCA-ordination of communities with participation of steppe species of the genus Iris showed that they are well separated in the space of the first two axes (See Fig. 2). The main axis is interpreted as a complex gradient of moisture-salinity variability. The second axis can be interpreted as the aridity-humidity gradient. The studied species of the genus Iris are plants of open habitats (steppes, meadows, river banks), therefore the lighting conditions (Lc) are critical for them (See Fig. 3-5). The critically important environmental factors also include the variability of moisture (fH) and the severity of the winter period (Cr). The low ecological amplitude of I. pumila and I. scariosa for a number of climatogenic environmental factors, such as aridity-humidity (Om) and associated soil moisture (Hd), and the amount of incoming heat (Tm) causes their confinement mainly to the steppe zone of the region. At the same time, the values of the continentality of climate factors (Kn) are in wider boundaries, especially for I. scariosa. Ordination analysis showed that, according to a complex of environmental factors, each species of the genus Iris occupies its own ecological niche. Therefore, in nature, the studied species are extremely rare in the same habitats and communities. According to the given values of ecological factors of the environment (See Table), I. pumila, I. scariosa and I. humilis in the Southern Urals have a rather narrow ecological amplitude, i.e. they are stenotopes, which largely determines their natural rarity in the region of the Southern Urals.

Productivity controls macrofauna diversity in the deep northern Gulf of Mexico

The α-diversity in two large-scale, systematic macrobenthos surveys (1983–1985 and 2000–2001) in the deep northern Gulf of Mexico (GoM) has been compared under strong vertical and horizontal productivity gradients to examine underlying factors that control the distribution of deep-sea diversity. We calculated the effective numbers of equally abundant species (Hill numbers) from 100 randomly selected individuals to examine spatial patterns of species richness and evenness. Macrofauna α-diversity was a negative parabolic function of depth; the minima occurred at high export POC flux on the upper continental slope and on the abyssal plain with extremely low input of POC; the maximum occurred at intermediate levels of macrofauna biomass and input of POC. The overall parabolic pattern of α-diversity was stable over the 20-year period and not statistically different between meso-scale depressions (e.g., basins and canyons) and their adjacent slope habitats; however, the diversity was significantly higher in the NE than the NW slope habitats. The observed Mid-Depth-Maximum (MDM) in α-diversity, we suggest, was likely a result of dynamic equilibrium between productivity and competitive exclusion. The higher diversity and productivity in the NE than the NW GoM at similar depth ranges suggests that, for the first time, the productivity-diversity relationship was observed independent of other depth-related factors. The findings provide a foundation for predicting the possible responses of diversity to climate change and anthropogenic impacts in the deep sea.

Peak in biomass driven by larger-bodied meso-predators in demersal fish communities between shelf and slope habitats at the head of a submarine canyon in the south-eastern Indian Ocean

This study investigated variations in the composition and biomass of demersal fish assemblages over a 570-metre depth gradient on the temperate, lower west coast of Australia (32° S) in the south-eastern Indian Ocean. Fish assemblages were sampled using Baited Remote Underwater Stereo Video systems (stereo-BRUVs, n = 284 deployments) from shallow waters around a mid-shelf island (Rottnest Island) to the continental slope within a submarine canyon (Perth Canyon). A total of 9013 individual fishes (i.e. ΣMaxN) belonging to 179 species and 75 families were identified. Multivariate statistical analyses revealed three distinct fish assemblages associated with the continental shelf (5–199 m), margin (200–300 m) and upper slope (300–570 m). A distance-based linear model revealed that among environmental covariates, benthic biota (sessile invertebrates and macroalgae) accounted for the highest proportion of variation in fish assemblage composition (16.9%) followed by depth (12.5%) and seabed relief (10.5%). Generalised additive models indicated higher biomass of fish associated with habitats characterised by benthic biota. Species richness decreased with increasing depth across the continental shelf but remained constant with increasing depth on the continental slope. Average fish length was not correlated with depth but was greatest at 200–400 m depth. The continental margin and upper slope habitats revealed a distinct change in assemblage composition as well as a peak in biomass of species that was dominated by larger-bodied meso-predators at the continental margin. The trends exhibited in fish assemblage characteristics across this broad depth range can inform ecosystem based management for deepwater fisheries resources.

Bowhead and Beluga Whale Distributions, Sighting Rates, and Habitat Associations in the Western Beaufort Sea in Summer and Fall 2009–16, with Comparison to 1982–91

We analyzed data from line-transect aerial surveys for marine mammals conducted in the western Beaufort Sea (shore to 72˚ N, 140˚–157˚ W) from July to October of 2009–16 to investigate the distribution, behaviors, sighting rates, and habitat use preferences of bowhead and beluga whales. The habitat use data allowed for direct comparison with data collected in the same area from 1982 to 1991. Both species are ice-adapted, migrating through leads in sea ice in spring, and are seasonal inhabitants of the western Beaufort Sea during summer and fall. From 2009 to 2016, bowheads were seen in all survey months, with the highest overall sighting rate (whales per km) in August. Bowhead sighting rates were highest in the whales’ preferred habitats: outer shelf habitat (51–200 m depth) in July and inner shelf-shallow habitat (≤ 20 m depth) in August, September, and October. Beluga whales were also seen in all survey months, with highest overall sighting rate in July. Beluga whales were overwhelmingly associated with continental slope habitat (201–2000 m depth) in all months. Bowhead distribution and depth preferences in summer months of 2009–16 differed from those observed in 1982–91, when bowheads were not seen during limited survey effort in July and preferred outer continental shelf habitat in August. These differences indicate that bowhead whale preference for shallow shelf habitat now occurs earlier in summer than it used to. Beluga distribution and depth preference remained similar between 1982–91 and 2009–16, with strong preference for continental slope during both periods. Differences in sea ice cover habitat association for both species are likely due more to the relative lack of sea ice in recent years compared to the earlier period than to shifts in habitat preference. Habitat partitioning between bowhead and beluga whales in the western Beaufort Sea remained evident except in July, when both species used continental slope habitat. In July – October 2009–16, the distribution, sighting rates, and behavior of both bowheads and belugas in the western Beaufort showed considerable interannual variation, which underscores the importance of annual sampling to accurate records of the complex western Beaufort Sea ecosystem.

Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

To fill data gaps on movements, behaviors and habitat use both near- and offshore, two programs were initiated to deploy satellite tags on basking sharks. Basking sharks are large filter feeding sharks that are second in size only to whale sharks. Similar to many megafauna populations, available data suggest that populations are below historic levels. In the northeast Pacific Ocean, the limited information on basking sharks comes from nearshore habitats where they forage. From 2010-2011, four sharks were tagged with pop-off satellite archival tags with deployments ranging from 9-240 days. The tags provided both transmitted and archived data on habitat use and geographic movement patterns. Nearshore, sharks tended to move north in the summer and prefer shelf and slope habitat around San Diego, Point Conception and Monterey Bay. The two sharks with 180 and 240 day deployments left the coast in the summer and fall. Offshore their paths diverged and by January one shark had moved to near the tip of the Baja Peninsula, Mexico and the other to the waters near Hawaii, USA. Vertical habitat use was variable both within and among individuals and changed as sharks moved offshore. Nearshore, most time was spent in the mixed layer but sharks did spend hours in cold waters below the mixed layer. Offshore vertical movements depended on location. The shark that went to Hawaii had a distinct diel pattern, with days spent at ~450-470 m and nights at ~250-300 m and almost no time in surface waters, corresponding with the diel migration of a specific portion of the deep scattering layer. The shark that moved south along the Baja Peninsula spent progressively more time in deep water but came to the surface daily. Movement patterns and shifts in vertical habitat and use are likely linked to shifts in prey availability. Data collected indicate the potential for large-scale movements and the need for international dialogue in any recovery efforts.

Factors affecting the importance of myctophids in the diet of the world’s seabirds

Mesopelagic myctophid fish are a key component of the world’s ocean food webs, linking primary consumers and predators. Among marine predators, seabirds are globally significant consumers, but the extent to which they feed on myctophids has been investigated only at the regional scale. This global-scale review of analyses of the stomach contents of 228 seabird species reveals that the occurrence of myctophids in seabird diets is extremely variable. However, myctophids do constitute a considerable amount of the food of penguins, the Procellariidae (shearwaters/petrels, etc.), and storm-petrels; in locations where birds are foraging in oceanic basin/shelf slope habitat; and among birds that feed at night. Recent analyses of the fatty acid signature of stomach oil emphasize that myctophids can be important prey also for seabirds exploiting oceanic habitats. Current efforts to survey seabirds’ distribution outside the breeding period, when they often become more oceanic, and their circadian activity may further support the global importance of myctophids as a pathway for carbon advection between marine compartments.

О некоторых сообществах петрофитных степей Среднего Урала

О некоторых сообществах петрофитных степей Среднего Урала

Crevice-Nesting Auklets are Early-Successional Species Requiring Disturbance to Persist

ABSTRACTAuklets (Aethia spp.) are small seabirds, endemic to the North Pacific Ocean, that nest in rock crevices on islands in Alaska and Russia. Nesting habitats for least (A. pusilla) and crested (A. cristatella) auklet colonies in the southern part of their range (Aleutian and Kuril Islands) are becoming overgrown by vegetation, which is fertilized by the auklets, making rock crevices unavailable for breeding. Colonization of newly created volcanic habitats suggests that auklets are habitat-limited in the southern range. The largest colonies there of least and crested auklets exist on lava slopes <100 years old. We propose that in the south, volcanic activity is required to maintain auklet populations. In contrast, colonies in the northern Bering Sea and Sea of Okhotsk show no indication of habitat limitation. They occur in more persistent talus slope habitats maintained by weathering, slumping, frost heaving, and tumbling. Biological processes there are slower and vegetation communities not as developed. We propose a conceptual model describing the interaction of geological and biological processes that influence auklet demography. We conclude that least and crested auklets require episodic disturbance (provided by volcanoes, earthquakes, and rock fall deposits) to maintain access to nest crevices. Auklets thereby provide an example of disturbance-adapted, early successional species that self-inhibit if their habitat is not regularly disturbed.

Echolocation for restoration: Odontocete monitoring in the Gulf of Mexico

In the late 1990s, George E. Ioup began studying echolocation clicks as a means of understanding marine mammals in the Gulf of Mexico (GOM). He also led one of the few research programs focused on pelagic species in this chronically impacted region in the years preceding the Deepwater Horizon oil spill. Today, passive acoustic monitoring (PAM) is one of the primary tools used to study the nearly 20 pelagic odontocete species found in the GOM, including sperm whales, beaked whales, dolphins, and Kogia species. Since 2010, PAM devices have been deployed nearly continuously in the region, driven by an urgent need to understand the long-term effects of both acute and chronic anthropogenic impacts on GOM marine mammal populations. Recent advances fueled by robust, reliable PAM technologies include the development of multi-year timeseries documenting changes in species densities across continental shelf and slope habitats, differentiating GOM odontocete species based on echolocation click properties, and leveraging long-term datasets to understand the influence of habitat variability on offshore species distributions. These capabilities are proving PAM is indispensable as an observation method for damage assessment, decision support, and restoration activities for marine mammals, especially inaccessible pelagic populations.

Understory host plant and insect gall diversity changes across topographic habitats differing in nutrient and water stress in the Brazilian Amazon rainforest

ABSTRACT Topographic gradients in terra firme forests are associated with pronounced changes in soil texture, soil nutrients and distance to the water-table, thereby creating different hydric and nutritional conditions for plants and their associated herbivore community. The aim of this study was to investigate galling species and host plant richness and gall species composition across topographic habitats differing in nutrient and water stress in the Brazilian Amazon rainforest. Nineteen 250 x 3 m plots were randomly sampled in the valley, slope, plateau-slope transition, and plateau habitats in terra firme forests. All individual dicotyledonous plants 1 to 3 meters high were examined for the presence of insect galls. Galling species and host plant richness differed significantly among the studied habitats and were higher in slope habitats (drier habitats), as expected. More humid areas (valleys) showed the lowest richness of galling species, and a lower number of understory host plants. PERMANOVA and PERMDISP results demonstrated that the gall species composition differed significantly in the valley, slope, plateau-slope transition, and plateau areas. However, these structural differences in species composition could be due to unequal dispersion of variability among forest habitats. Our data suggested that spatial heterogeneity, such as a mosaic of local water status and nutrient availability resulting from the topographic conditions, can affect host plants and their associated galling insects.

Shallow landslides as drivers for slope ecosystem evolution and biophysical diversity

Shallow landslides may be seen as local disturbances that foster the evolution of slope landscapes as part of their self-regulating capacity. Gaining insight into how slope ecosystems function and evolve could make eco-engineering interventions on slopes more successful. The objective of the present study is to detect traits of shallow landslide-triggered ecosystem evolution, self-regulation and biophysical diversity in a small-scale landslide-prone slope in Northeast Scotland. A protocol was defined to explore the emergence of landslide-driven slope habitats. This protocol studied plant diversity, species richness and plant biomass differences and their interactions with certain soil and topographic attributes at three slope strata during two consecutive growing seasons following an assemblage of shallow landslide events. Plant species and soil properties with potential as indicators of the different landslide-driven slope habitats and landscape evolution were also considered. Shallow landslides contributed to biophysical diversity and created distinct slope habitats within the landscape. Habitat differences in terms of species richness and composition were a direct consequence of the slope self-regulation. Certain plant species were found to be valid indicators of landslide-driven biophysical diversity. Soil total nitrogen and resistance to penetration were related to slope habitat and landscape evolution. As expected, plant establishment relied upon light and nitrogen trade-offs, which in turn were influenced by landscape topography. The insights derived from this study will be useful in slope restoration, particularly in harmonising effective actions with the functioning of landslide-prone ecosystems. Further research directions to clarify the observed variability and interactions are highlighted.

Marine fish community structure and habitat associations on the Canadian Beaufort shelf and slope

Marine fishes in the Canadian Beaufort Sea have complex interactions with habitats and prey, and occupy a pivotal position in the food web by transferring energy between lower- and upper-trophic levels, and also within and among habitats (e.g., benthic-pelagic coupling). The distributions, habitat associations, and community structure of most Beaufort Sea marine fishes, however, are unknown thus precluding effective regulatory management of emerging offshore industries in the region (e.g., hydrocarbon development, shipping, and fisheries). Between 2012 and 2014, Fisheries and Oceans Canada conducted the first baseline survey of offshore marine fishes, their habitats, and ecological relationships in the Canadian Beaufort Sea. Benthic trawling was conducted at 45 stations spanning 18–1001m depths across shelf and slope habitats. Physical oceanographic variables (depth, salinity, temperature, oxygen), biological variables (benthic chlorophyll and integrated water-column chlorophyll) and sediment composition (grain size) were assessed as potential explanatory variables for fish community structure using a non-parametric statistical approach. Selected stations were re-sampled in 2013 and 2014 for a preliminary assessment of inter-annual variability in the fish community. Four distinct fish assemblages were delineated on the Canadian Beaufort Shelf and slope: 1) Nearshore-shelf: <50m depth, 2) Offshore-shelf: >50 and ≤200m depths, 3) Upper-slope: ≥200 and ≤500m depths, and 4) Lower-slope: ≥500m depths. Depth was the environmental variable that best explained fish community structure, and each species assemblage was spatially associated with distinct aspects of the vertical water mass profile. Significant differences in the fish community from east to west were not detected, and the species composition of the assemblages on the Canadian Beaufort Shelf have not changed substantially over the past decade. This community analysis provides a framework for testing hypotheses regarding the trophic dynamics and ecosystem roles of Beaufort Sea marine fishes, including biological linkages (i.e., fish movements and trophic interactions) among offshore habitats. Understanding regional-scale habitat associations will also provide context to identify potentially unique and/or sensitive habitats and fish community characteristics, thus aiding identification of ecologically and biologically significant areas, and to inform conservation efforts.

Contrasting patterns of residency and space use of coastal sharks within a communal shark nursery

The benefits of marine protected areas are difficult to estimate for mobile species, but their effectiveness can be increased if essential habitats, such as nursery areas, are protected. In the present study we examined movements of juvenile blacktip reef (Carcharhinus melanopterus) and sicklefin lemon (Negaprion acutidens) sharks in a coastal nursery in northern Australia. Telemetry-derived data were modelled using Brownian bridges and overlaid with maps of habitats and no-take zones. Juvenile N. acutidens were typically residents (≥30 days) of the nursery with small areas of core space use (&lt;1.9km2), whereas juvenile C. melanopterus were non-residents (&lt;30 days) and used larger areas (&lt;5.6km2). Both species exhibited positive selection for sandflats and mangroves, and avoidance of deeper lagoonal and slope habitats. Monthly patterns were examined only for resident N. acutidens, and residency decreased with increasing shark length and varied seasonally for males but not females. Space use showed weak declines with increasing tidal range, and slight increases with mean air pressure, rainfall and shark length. Protecting sandflat and vegetated habitats may increase the efficacy of no-take zones for juvenile N. acutidens, because they exhibit residency and affinity to these features. Conversely, such protection will be of limited benefit for juvenile C. melanopterus, because they exhibit low residency and broader movements.

Sediment generation by Halimeda on atoll interior coral reefs of the southern Maldives: A census-based approach for estimating carbonate production by calcareous green algae

Methods for quantifying rates and size fractions of carbonate sand production on reefs remain limited, despite the urgent need for such data to support assessments of reef island and tropical beach-dominated shoreline resilience. Here we present a census-based approach that supports estimates of sediment generation by the calcareous green alga Halimeda spp., which is an often conspicuous reef and lagoon substrate coloniser. Based on data from Kandahalagala (South Huvadhoo atoll, southern Maldives), we present carbonate sediment production data for the two dominant Halimeda spp. (Halimeda macrophysa and Halimeda micronesica) that occur on the reef flat and reef slope habitats. Whilst total mean production rates by Halimeda spp. are similar in both habitats (reef flat average, 67.49gCaCO3m−2yr−1; reef slope, 70.89g), individual species contributions differ markedly. H. micronesica dominates on the reef flat (annual mean 41.91gCaCO3m−2yr−1, compared to 25.08g by H. macrophysa), whilst production is dominated by H. macrophysa on the reef slope (H. macrophysa 40.49g, H. micronesica 29.01gCaCO3m−2yr−1,). In terms of sediment generation we show that these species also contribute very differently to the sediment reservoir. Whilst the sedimentary breakdown products from H. micronesica are somewhat bimodal (~17% is in the medium to very coarse sand fraction, and ~76% in the silt and clay fraction), almost all (>90%) of the segments produced by H. macrophysa rapidly degrade to silt and clay sized sediment. Based on our census data this suggests that Halimeda spp. will contribute only between 7 and 9gm−2yr−1 of sand grade sediment on the reef flat and shallow slope habitats, but ~55–60gm−2yr−1 of mud grade sediment. Scaled to the total area of combined reef habitat around Kandahalagala (~130,583m2) this equates to Halimeda spp. producing ~2192kg of sand-grade sediment, but ~15,181kg of mud-grade sediment per year. However, sediment compositional data suggests that Halimeda sp. are actually a very minor constituent of reef and islands sediments, especially in the fine sediment fractions. This 1) suggests that much of the predominantly finer-grained sediment generated by Halimeda has little actual relevance to the later stages of reef island development, and 2) highlights the potential for marked discrepancies in terms of sediment generating reef species abundance and resultant sediment generation rates, especially in terms of the types and sizes of sediment that are appropriate to supply adjacent beaches and islands.

Pristine semi-arid areas in northeastern Brazil remain mainly on slopes of mountain ranges: a case study based on bird community of Serra de Santana

Pristine areas are becoming rare everywhere, resulting in scattered fragments of natural environments. In the Brazilian steppe savanna, this situation requires attention because habitats with higher economic value are underrepresented by the protected area system. Between 2009 and 2010, we surveyed 60 sites with differing landscapes such as plateaus, slopes, and lowlands in the Serra de Santana. At each site, we applied standardized bird survey methods and compared the observed and projected richness of each landscape. We recorded 189 species, with the highest species richness in the slope habitat, followed by plateaus, and then lowlands. In the slope habitat, there were more forest-dependent species, as well as more species with high and medium sensitivity to disturbance. Endemic species with high and medium sensitivity to disturbances were restricted to slopes and some fragments of the plateaus. Our results show that the region is an important area due to the high bird species richness and presence of e...

Marine ostracodes from Paleogene hydrocarbon seep deposits in Washington State, USA and their ecological structure

Invertebrate fossils described from ancient hydrocarbon seep deposits represent diverse groups, e.g., brachiopods, mollusks, decapod crustaceans, worm tubes, and rare echinoderms, but the fossil record of ostracodes from hydrocarbon seep deposits is still very limited, making their ecology and evolutionary history still little known. We found fossil ostracodes in eight Eocene to Oligocene hydrocarbon seep deposits in the Humptulips, Lincoln Creek, Makah, and Pysht formations in western Washington State, USA. They represent eleven taxa belonging to genera found in a wide range of shelf to slope habitats: Acanthocythereis, Loxoconcha?, Cytherella, Cytheropteron, Macropyxis?, Krithe, Paracosta, Pontocythere?, Propontocypris, Palmoconcha, and Neonesidea? Acanthocythereis acroreticulata from one late Oligocene seep deposit in the Lincoln Creek Formation is the oldest and northernmost record for this species. The hydrocarbon seep ostracode faunas from Washington appear to be benthos-dominated, showing the same ecological structure and pattern of phylogenetic relatedness as ostracodes from Miocene and Quaternary seep sediments from Italy and off Ireland. We suggest that the benthos-dominated structure has been stable for ostracodes in hydrocarbon seep environments and/or has a higher preservation potential than the nektobenthos-dominated structure.

Porphyrocrinus daniellalevyae n. sp. (Echinodermata: Crinoidea), a sea lily from the tropical western Atlantic with a unique crown pattern.

Porphyrocrinus daniellalevyae, new species, is described from irregular, hard-substrate, deep island slope habitats in the tropical western Atlantic Ocean (northwestern Bahamas and, probably, Honduras). It represents the first record of the genus from the western Atlantic, and is the first crinoid, living or fossil, known to gradually increase its number of rays with increasing size and, ostensibly, growth. The four known specimens have 8, 12, 14 and 15 radial ossicles, which give rise to undivided arms. The method of augmentation is unknown, although the possibility of autotomy of one and regrowth of two in its place is discussed. Augmentation of radial number may also account for the absence of an aboral nerve ring associated with the radial ring, unlike the arrangement in almost all living crinoids in which the nervous system has been examined. Ligamentary articulations (trifascial synarthries) exhibit fulcral ridge-and groove architecture between arm ossicle pairs that remains to be described for other members of the genus. The species also exhibits a filamentous arm tip lacking pinnules that has only been described for one other species of Porphyrocrinus.

Holobiont assemblages of dominant coral species (Symbiodinium types and coral species) shape Caribbean reef community structure

&lt;div data-canvas-width="420.5696489780114"&gt;Investigaciones de la estructura de comunidades coralinas sugieren que escalas espacio temporales cortas son responsables de patrones en ecosistemas marinos tropicales. La combinación coral y su zooxantela, u holobionte, puede ser la entidad ecológica modificada por estos factores. La estructura de la comunidad de corales podría ser mejor entendida usando el holobionte como unidad indivisible de la comunidad. Investigaciones recientes en diversidad de zooxantelas (Symbiodinium&lt;/div&gt;&lt;div data-canvas-width="243.60164017005522"&gt;spp.) han revelado asociaciones de tipo específicas, así como generalistas dependiendo del hospedero. Su distribución depende tanto del hospedero como de las condiciones ambientales. Este estudio determino la identidad molecular de estos simbiontes en comunidades de corales duros (Scleractinia y Milleporina) en 27 localidades en el talud arrecifal superior (zona mixta) en Cartagena, Colombia. La identificación de zooxantelas se realizó mediante análisis de RFLPs (18S, SSU, rDNA, por sus siglas en inglés), DGGE y secuenciación de ADN (ITS2, rDNA). Se encontró variación intra e intercolonial, dependiendo de la especie del hospedero. Se determinaron diferentes holobiontes, como diferentes unidades ecológicas. Estas unidades correspondían a una minoría en la diversidad de especies, pero dominantes (p.ej., Orbicella spp.). Tomando cada holobionte como variable, se realizó un análisis de la estructura comunitaria y fue comparado con un análisis tomando solamente las especies de coral. Mayores similitudes entre estaciones se encontraron cuando se usaron los holobiontes. Las especies dominantes O. annularis&lt;/div&gt;&lt;div data-canvas-width="10.060996080065763"&gt;y O. faveolata formaron en cada caso diferentes holobiontes, dependiendo de la profundidad. La preferencia hacia un tipo específico de zooxantela podría estar bajo mayor presión selectiva de lo que anteriormente se pensaba. © Acad. Colomb. Cienc. Ex. Fis. Nat. 2016.&lt;/div&gt;

Changes in habitat utilization of slope-spawning flatfish across a bathymetric gradient

AbstractUnderstanding how fish distributions may change in response to environmental variability is important for effective management of fish populations, as predicted climate change will likely alter their habitat use and population dynamics. This research focused on two commercially- and ecologically-important flatfish species in the eastern Bering Sea (EBS), Greenland halibut ( Reinhardtius hippoglossoides ) and Pacific halibut ( Hippoglossus stenolepis ), which may be especially sensitive to climate-induced shifts in habitat due to strong seasonally and ontogenetically variable distributions. We analysed data from fishery-dependent and fishery-independent sources to determine how environmental variability influenced habitat use, thus gaining a uniquely comprehensive range of seasonal and geographic coverage of each species’ distribution. Greenland and Pacific halibut exhibited strong and contrasting responses to changes in temperature on the shelf, with catches decreasing and increasing, respectively, beyond 1 °C. The effect of temperature was not as prominent along the slope, suggesting that slope habitats may provide some insulation from shelf-associated environmental variability, particularly for Greenland halibut. With warming, Greenland halibut exhibited more of a bathymetric shift in distribution, while the shift was more latitudinal for Pacific halibut. Our results suggest that habitat partitioning may, in part, explain differences in Greenland and Pacific halibut distributions. This research adds to our understanding of how the distributions of two fish species at opposite extremes of their ranges in the EBS – Greenland halibut at the southernmost edge and Pacific halibut at the northernmost edge – may shift in relation to a changing ocean environment.

Deep-sea diversity patterns are shaped by energy availability.

The deep ocean is the largest and least-explored ecosystem on Earth, and a uniquely energy-poor environment. The distribution, drivers and origins of deep-sea biodiversity remain unknown at global scales. Here we analyse a database of more than 165,000 distribution records of Ophiuroidea (brittle stars), a dominant component of sea-floor fauna, and find patterns of biodiversity unlike known terrestrial or coastal marine realms. Both patterns and environmental predictors of deep-sea (2,000-6,500 m) species richness fundamentally differ from those found in coastal (0-20 m), continental shelf (20-200 m), and upper-slope (200-2,000 m) waters. Continental shelf to upper-slope richness consistently peaks in tropical Indo-west Pacific and Caribbean (0-30°) latitudes, and is well explained by variations in water temperature. In contrast, deep-sea species show maximum richness at higher latitudes (30-50°), concentrated in areas of high carbon export flux and regions close to continental margins. We reconcile this structuring of oceanic biodiversity using a species-energy framework, with kinetic energy predicting shallow-water richness, while chemical energy (export productivity) and proximity to slope habitats drive deep-sea diversity. Our findings provide a global baseline for conservation efforts across the sea floor, and demonstrate that deep-sea ecosystems show a biodiversity pattern consistent with ecological theory, despite being different from other planetary-scale habitats.