Rhyme-like Repetitions in Songs of Humpback Whales

Humpback whales (Megaptera novaeangliae) sing long, complex songs which continually change over time. In certain time periods the songs contain repeating patterns which structurally resemble human rhyming, and which, like human rhyming, tend to occur in highly rhythmical contexts. We speculate that humpback whales may use these repetitions as mnemonic devices, much as humans are thought to use rhymes. With this speculation in mind we examine 548 humpback whale songs from 7 years in the eastern North Pacific and 12 years in the western North Atlantic oceans. We find that rhyme-like structures are most likely to occur in songs containing the most material to be remembered.     

Stable Isotopes Provide Insight into Population Structure and Segregation in Eastern North Atlantic Sperm Whales

In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen- isotope ratios (δ¹⁸O) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (δ¹⁵N: δ¹³C) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in δ¹⁵N and δ¹⁸O values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in δ¹⁵N, δ¹³C and δ¹⁸O values in the period up to age 20, and in the ontogenetic variation of δ¹⁵N and δ¹⁸O values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted.     

Patterns of Spatial and Temporal Distribution of Humpback Whales at the Southern Limit of the Southeast Pacific Breeding Area

Understanding the patterns of spatial and temporal distribution in threshold habitats of highly migratory and endangered species is important for understanding their habitat requirements and recovery trends. Herein, we present new data about the distribution of humpback whales (Megaptera novaeangliae) in neritic waters off the northern coast of Peru: an area that constitutes a transitional path from cold, upwelling waters to warm equatorial waters where the breeding habitat is located. Data was collected during four consecutive austral winter/spring seasons from 2010 to 2013, using whale-watching boats as platforms for research. A total of 1048 whales distributed between 487 groups were sighted. The spatial distribution of humpbacks resembled the characteristic segregation of whale groups according to their size/age class and social context in breeding habitats; mother and calf pairs were present in very shallow waters close to the coast, while dyads, trios or more whales were widely distributed from shallow to moderate depths over the continental shelf break. Sea surface temperatures (range: 18.2–25.9°C) in coastal waters were slightly colder than those closer to the oceanic realm, likely due to the influence of cold upwelled waters from the Humboldt Current system. Our results provide new evidence of the southward extension of the breeding region of humpback whales in the Southeast Pacific. Integrating this information with the knowledge from the rest of the breeding region and foraging grounds would enhance our current understanding of population dynamics and recovery trends of this species.     

Actinocyclus exiguus sp. nov. from the southern parts of the Indian and Atlantic Oceans

A new species, Actinocyclus exiguus, a small centric diatom, is described from the southern Indian and Atlantic Oceans. The pseudonodulus, a diagnostic feature of the genus and family, has not been seen in the light microscope and is more easily seen on the inside of eroded valves with the aid of the scanning electron microscope. A. exiguus is compared to closely related species.     

New Pogonophora from the Atlantic and Pacific Oceans

A study of a collection of Pogonophora, made by the R.V. "Vema" in the Atlantic and Pacific Oceans, has revealed a total of 20 species. One of these, Lamellisabella ivanovi, was already known, the rest appear to be new. Seven species are described in detail, the others being represented only by tubes or insignificant fragments.     

Phytoplankton across Tropical and Subtropical Regions of the Atlantic,Indian and Pacific Oceans

We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal component assemblage), including several pennate taxa, Planktoniella sol, Hemiaulus hauckii and Pseudo-nitzschia spp., in the divergence regions. Our findings indicate that consistent assemblages of co-occurring phytoplankton taxa can be identified and that their distribution is best explained by a combination in different degrees of both environmental and historical influences.     

The social and reproductive biology of Humpback Whales: an ecological perspective

Existing knowledge of the social organization, mating system and reproduction of Humpback Whales (Megaptera novaeangliae) is reviewed to assess how our current understanding of this wide-ranging marine mammal fits into the predictive framework developed from ecological studies of more accessible terrestrial taxa. The small unstable groups characteristic of this species on its summer feeding grounds appear to be a function of absence of predation and of the patchy, mobile nature of most prey; the absence of territoriality and the minimal importance of kinship in associations are also predictable consequences of the latter. The mating system is similar to both leks and to male dominance polygyny, in which males display (sing) or directly compete (perhaps sometimes in coalitions) for access to females. However, the rigid spatial structure characteristic of classic leks is absent. The mating system of this species is sufficiently different to merit a novel category, and ‘floating lek’ is proposed. The widespread distribution of females resulting from absence of both predation and resources during the breeding season preclude simultaneous monopolization by males of more than one potential mate. Furthermore, these factors, together with a male-biased operational sex ratio, minimize the possibility of competition among females. The intensity of intrasexual competition among males conforms to predictions derived from information on testis size and from expectation of future reproductive success. Female choice and, to a lesser extent, differential allocation of competitive effort by males, appears likely. Lack of interpopulation variation in social and mating behaviour, and in general reproductive biology, is likely a response to similarity of marine environmental conditions. Year-to-year variation in reproductive rates may be linked to variations in the abundance of prey. The invariably uniparous nature of female Humpback Whales is assumed to be related to the energetic demands of lactation, and the lower ratio of available energy partitioned to reproduction that is characteristic of larger mammals. The reversed sexual size dimorphism of this species may reflect different selective pressures on males and females. Finally, there is now evidence that, as in some other taxa, offspring sex ratio is related to maternal condition.     

Large-Scale Examination of Spatio-Temporal Patterns of Drifting Fish Aggregating Devices (dFADs) from Tropical Tuna Fisheries of the Indian and Atlantic Oceans

Since the 1990s, massive use of drifting Fish Aggregating Devices (dFADs) to aggregate tropical tunas has strongly modified global purse-seine fisheries. For the first time, a large data set of GPS positions from buoys deployed by French purse-seiners to monitor dFADs is analysed to provide information on spatio-temporal patterns of dFAD use in the Atlantic and Indian Oceans during 2007-2011. First, we select among four classification methods the model that best separates “at sea” from “on board” buoy positions. A random forest model had the best performance, both in terms of the rate of false “at sea” predictions and the amount of over-segmentation of “at sea” trajectories (i.e., artificial division of trajectories into multiple, shorter pieces due to misclassification). Performance is improved via post-processing removing unrealistically short “at sea” trajectories. Results derived from the selected model enable us to identify the main areas and seasons of dFAD deployment and the spatial extent of their drift. We find that dFADs drift at sea on average for 39.5 days, with time at sea being shorter and distance travelled longer in the Indian than in the Atlantic Ocean. 9.9% of all trajectories end with a beaching event, suggesting that 1,500-2,000 may be lost onshore each year, potentially impacting sensitive habitat areas, such as the coral reefs of the Maldives, the Chagos Archipelago, and the Seychelles.     

The Gondwana Breakup and the History of the Atlantic and Indian Oceans Unveils Two New Clades for Early Neobatrachian Diversification

The largest anuran diversity belongs to the Neobatrachia, which harbor more than five thousand extant species. Here, we propose a new hypothesis for the historical aspects of the neobatrachian evolution with a formal biogeographical analysis. We selected 12 genes for 144 neobatrachian genera and four archaeobatrachian outgroups and performed a phylogenetic analysis using a maximum likelihood algorithm with the rapid bootstrap test. We also estimated divergence times for major lineages using a relaxed uncorrelated clock method. According to our time scale, the diversification of crown Neobatrachia began around the end of the Early Cretaceous. Our phylogenetic tree suggests that the first split of Neobatrachia is related to the geological events in the Atlantic and Indian Oceans. Hence, we propose names for these clades that indicate this connection, i.e., Atlanticanura and Indianura. The Atlanticanura is composed of three major neobatrachian lineages: Heleophrynidae, Australobatrachia and Nobleobatrachia. On the other hand, the Indianura consists of two major lineages: Sooglossoidea and Ranoides. The biogeographical analysis indicates that many neobatrachian splits occurred as a result of geological events such as the separation between South America and Africa, between India and the Seychelles, and between Australia and South America.     

Phylogenetic diversity of subsurface marine microbial communities from the Atlantic and Pacific Oceans.

The extent of the diversity of marine prokaryotes is not well known, primarily because of poor cultivability. However, new techniques permit the characterization of such organisms without culturing, via 16S rRNA sequences obtained directly from biomass. We performed such an analysis by polymerase chain reaction amplification with universal primers on five oligotrophic open-ocean samples: from 100-m (three samples) and 500-m depths in the western California Current (Pacific Ocean) and from a 10-m depth in the Atlantic Ocean near Bermuda. Of 61 clones, 90% were in clusters of two or more related marine clones obtained by ourselves or others. We report 15 clones related to clone SAR 11 found earlier near Bermuda (S. J. Giovannoni, T. B. Britschgi, C. L. Moyer, and K. G. Field, Nature [London] 345:60-63, 1990), 11 related to marine cyanobacteria, 9 clustered in a group affiliated with gram-positive bacteria, 9 in an archaeal cluster we recently described (mostly from the 500-m sample), 4 in a novel gamma-proteobacterial cluster, and 6 in three two-membered clusters (including other archaea). One clone was related to flavobacteria. Only the cyanobacteria plus one other clone, related to Roseobacter denitrificans (formerly Erythrobacter longus Och114), were within 10% sequence identity to any previously sequenced cultured organism in a major data base. We never found more than two occurrences of the same sequence in a sample, although four times we found identical sequences between samples, two of which were between oceans; one of these sequences was also identical to SAR 11.(ABSTRACT TRUNCATED AT 250 WORDS)     

Population Genetic Structure of the Magnificent Frigatebird Fregata magnificens (Aves,Suliformes) Breeding Colonies in the Western Atlantic Ocean

The Magnificent Frigatebird Fregata magnificens has a pantropical distribution, nesting on islands along the Atlantic and Pacific coasts. In the Caribbean, there is little genetic structure among colonies; however, the genetic structure among the colonies off Brazil and its relationship with those in the Caribbean are unknown. In this study, we used mtDNA and microsatellite markers to infer population structure and evolutionary history in a sample of F. magnificens individuals collected in Brazil, Grand Connétable (French Guyana), and Barbuda. Virtually all Brazilian individuals had the same mtDNA haplotype. There was no haplotype sharing between Brazil and the Caribbean, though Grand Connétable shared haplotypes with both regions. A Bayesian clustering analysis using microsatellite data found two genetic clusters: one associated with Barbuda and the other with the Brazilian populations. Grand Connétable was more similar to Barbuda but had ancestry from both clusters, corroborating its “intermediate” position. The Caribbean and Grand Connétable populations showed higher genetic diversity and effective population size compared to the Brazilian population. Overall, our results are in good agreement with an effect of marine winds in isolating the Brazilian meta-population.     

Post-Fledging Dispersal of King Penguins (Aptenodytes patagonicus) from Two Breeding Sites in the South Atlantic

Most studies concerning the foraging ecology of marine vertebrates are limited to breeding adults, although other life history stages might comprise half the total population. For penguins, little is known about juvenile dispersal, a period when individuals may be susceptible to increased mortality given their naïve foraging behaviour. Therefore, we used satellite telemetry to study king penguin fledglings (n = 18) from two sites in the Southwest Atlantic in December 2007. The two sites differed with respect to climate and proximity to the Antarctic Polar Front (APF), a key oceanographic feature generally thought to be important for king penguin foraging success. Accordingly, birds from both sites foraged predominantly in the vicinity of the APF. Eight king penguins were tracked for periods greater than 120 days; seven of these (three from the Falkland Islands and four from South Georgia) migrated into the Pacific. Only one bird from the Falkland Islands moved into the Indian Ocean, visiting the northern limit of the winter pack-ice. Three others from the Falkland Islands migrated to the eastern coast of Tierra del Fuego before travelling south. Derived tracking parameters describing their migratory behaviour showed no significant differences between sites. Nevertheless, generalized linear habitat modelling revealed that juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height and chlorophyll variability. Birds from South Georgia spent more time in deeper waters with low sea surface temperature and sea surface height, but high concentrations of chlorophyll. Our results indicate that inexperienced king penguins, irrespective of the location of their natal site in relation to the position of the APF, develop their foraging skills progressively over time, including specific adaptations to the environment around their prospective breeding site.     

Population genetics of the bigeye thresher shark <Emphasis Type="Italic">Alopias superciliosus</Emphasis> in the Atlantic and Indian Oceans: implications for conservation

Population structure and genetic connectivity are pivotal contributions to the establishment of conservation strategies for fisheries management, in particular for highly migratory species that are affected by commercial fisheries. This study used partial sequences of mitochondrial DNA control region to determine the genetic structure of the bigeye thresher shark Alopias superciliosus in the Atlantic and Indian Oceans. A total of 858 base pairs of mtDNA CR from 228 individuals were analyzed. The resulting nucleotide diversity (π) was 0.0011?±?0.0008 and the haplotype diversity (h) was 0.127?±?0.030. These are the lowest diversities registered in elasmobranchs with this genetic marker. Two genetically distinct lineages were identified, one of them represented by 3.9% of the analyzed individuals and none restricted to any particular area. Simulated scenarios of population structure, tested with AMOVA and pairwise Φ_ST did not result in significant values indicating high connectivity among all sampled groups. The absence of population structure, even between Atlantic and Indian Oceans, corroborates the high dispersal ability of this species. The low genetic diversity detected in this species and the identification of two historical lineages occurring in sympatry, one represented by a very small number of individuals, should be considered in the conservation efforts and management plans of A. superciliosus.     

Diversity of isopods (Crustacea): new data from the Arctic and Atlantic Oceans

New data on the diversity pattern of isopods (Crustacea) from the northern most part of the North Atlantic and the Arctic Oceans is presented. The pattern of diversity with depth is similar at depths <1000m, but differs considerably below about 1000m. In the Arctic the diversity of isopods (expressed both as numbers of species per sled and expected number of species) increased with increased depth to a maximum at depths of about 320 to 1100m, but then declined towards deeper waters. There was a significant increase in numbers per sled and in the expected number of species with increased depth in the northernmost part of the North Atlantic Ocean. Additionally, changes occurred in the relative composition of the shallow and deep water fauna, with asellote isopods being relatively larger part of the isopod fauna in the Arctic than in the northern most part of the North Atlantic. This indicates major faunistic changes occurring at the Greenland-Iceland-Faeroe Ridge, possibly caused by rapid changes in the temperature. Furthermore, that the low diversity of the Arctic deep-sea is a regional phenomenon, and not a part of a large scale latitudinal pattern in the North Atlantic.     

Differences in species diversity of Monogenea between the Pacific and Atlantic Oceans

Data from five extensive surveys each in the Pacific and Atlantic Oceans show that relative species diversity (number of parasite species per host species) of gill Monogenea of coastal marine fishes is greater in the northern and southwestern Pacific than in the northeastern and central- and southwestern Atlantic. Relative species diversity is markedly lower in the cold northeastern Atlantic than in the warmer parts of the Atlantic examined, and in the northern Pacific than in the warm southwestern Pacific. The difference between the northern Pacific and Atlantic is entirely or almost entirely due to a much greater number of species of Gyrodactylidae in the northern Pacific. A species-area relationship cannot explain the difference, because the area of the northern Pacific is not larger than that of the northern Atlantic and because Gyrodactylidae are cold-water forms which cannot have immigrated from warmer seas. The difference is tentatively explained by an evolutionary time hypothesis: more species of Gyrodactylidae have accumulated in the much older Pacific than in the Atlantic Ocean. Alternatively, an ecological time hypothesis may explain the difference: ice sheets during the last glaciation covered much more of the continental shelf in the northern Atlantic than in the northern Pacific, possibly extinguishing more Monogenea in the former than in the latter Ocean.     

Modeling the Distribution of Geodia Sponges and Sponge Grounds in the Northwest Atlantic

Deep-sea sponge grounds provide structurally complex habitat for fish and invertebrates and enhance local biodiversity. They are also vulnerable to bottom-contact fisheries and prime candidates for Vulnerable Marine Ecosystem designation and related conservation action. This study uses species distribution modeling, based on presence and absence observations of Geodia spp. and sponge grounds derived from research trawl catches, as well as spatially continuous data on the physical and biological ocean environment derived from satellite data and oceanographic models, to model the distribution of Geodia sponges and sponge grounds in the Northwest Atlantic. Most models produce excellent fits with validation data although fits are reduced when models are extrapolated to new areas, especially when oceanographic regimes differ between areas. Depth and minimum bottom salinity were important predictors in most models, and a Geodia spp. minimum bottom salinity tolerance threshold in the 34.3-34.8 psu range was hypothesized on the basis of model structure. The models indicated two currently unsampled regions within the study area, the deeper parts of Baffin Bay and the Newfoundland and Labrador slopes, where future sponge grounds are most likely to be found.