Warm Temperate Waters Research Articles

Changes in biodiversity and species associations along a latitudinal gradient

Biodiversity is currently threatened at local, regional, and global scales, and identifying the species that are vulnerable to these changes is essential for conservation efforts. For example, the breadth of species’ ranges may offer important clues to their susceptibility to loss, as widespread species may be more resistant to loss than species with a narrower range breadth. To determine the potential for shifts in community interactions along the latitudinal geographic ranges of species, we examined pair-wise associations between narrow-range endemic and widespread rocky intertidal species. We surveyed rocky intertidal species composition at eight sites along the California coast from San Diego to Cape Mendocino. Four sites were south of Point Conception, and four sites were north of Point Conception. Point Conception is a major biogeographic feature for coastal marine species, where sea surface temperatures transition from cool temperate waters in the north to warm temperate waters in the south. To determine whether pair-wise species associations were significant, we compared the observed communities’ standardized effect size to a null model to determine which species occurred together more or less often than by chance. Across all sites, widespread species were considerably more abundant than narrow-range endemic species, and the majority of species were widespread. However, total species richness was unrelated to the number of widespread species, and was, instead, determined by the number of narrow-range endemic species present at a site. Our analyses suggest that species are more aggregated than segregated south of Point Conception, but the opposite is true north of Point Conception. Additionally, we found that species associations between narrow-range endemics drove the overall patterns in species associations. One possible explanation for these patterns is that positive interactions, especially those involving narrow-range endemic species, are more important in southern California’s more thermally stressful intertidal habitats.

Macroparasites of angelfish Brama brama (Bonnaterre, 1788) in the southern Benguela Current ecosystem

The angelfish Brama brama is a mesopelagic species distributed circumglobally in temperate to warm-temperate waters, including continental-shelf-edge and upper-slope waters of the Benguela Current ecosystem. Little is known about the parasite assemblage of Benguela B. brama, with only three parasite taxa having previously been documented from this species in the southern Benguela. This study describes the macroparasites recorded from 35 B. brama collected during research surveys off the west coast of South Africa in 2015 and 2016. A total of six macroparasite taxa were documented, including the nematode Anisakis pegreffii, the copepod Hatschekia conifera, the cestode Hepatoxylon trichiuri, an acanthocephalan from the genus Rhadinorhynchus, a monogenean from the family Diclidophoridae, and an unidentified species. Three of these (He. trichiuri, Rhadinorhynchus sp. and the unidentified species) had not previously been found to infect B. brama. The most prevalent macroparasite taxa were A. pegreffii (94%), the unidentified species (71%) and Ha. conifera (60%). Two of the parasites, Ha. conifera and He. trichiuri, showed seasonal variation in infection, and infection with the latter was positively correlated with host length. These findings increase our knowledge of B. brama biology and contribute to our understanding of the biodiversity of the southern Benguela ecosystem.

First record of common bottlenose dolphin (Tursiops truncatus) in Canadian Pacific waters

BackgroundCommon bottlenose dolphins (Tursiops truncatus) are distributed globally in tropical and warm-temperate waters with coastal and offshore ecotypes known. In the eastern North Pacific Ocean, common bottlenose dolphins are typically found in offshore waters as far as 41° N and in coastal waters as far as 38° N. Despite considerable survey effort, the species has not been previously recorded in Canadian Pacific waters.ResultsOn 29 July 2017, a group of approximately 200 common bottlenose dolphins were observed together with approximately 70 false killer whales (Pseudorca crassidens) in waters of 16.5° C at 50° N during a pelagic seabird and marine mammal survey off the west coast of northern Vancouver Island, British Columbia, Canada.ConclusionsThis sighting represents the only occurrence of common bottlenose dolphins recorded in Canadian Pacific waters and, to our knowledge, is the most northerly record for this species in the eastern North Pacific. It is also the first sighting record of false killer whales in non-coastal waters in British Columbia, Canada. The occurrence of both species may be associated with a prolonged period of warming in offshore regions of the eastern North Pacific.

Crossing the front: contrasting storm-forced dispersal dynamics revealed by biological, geological and genetic analysis of beach-cast kelp.

The subtropical front (STF) generally represents a substantial oceanographic barrier to dispersal between cold-sub-Antarctic and warm-temperate water masses. Recent studies have suggested that storm events can drastically influence marine dispersal and patterns. Here we analyse biological and geological dispersal driven by two major, contrasting storm events in southern New Zealand, 2017. We integrate biological and physical data to show that a severe southerly system in July 2017 disrupted this barrier by promoting movement of substantial numbers of southern sub-Antarctic Durvillaea kelp rafts across the STF, to make landfall in mainland NZ. By contrast, a less intense easterly storm (Cyclone Cook, April 2017) resulted in more moderate dispersal distances, with minimal dispersal between the sub-Antarctic and mainland New Zealand. These quantitative analyses of approximately 200 freshly beach-cast kelp specimens indicate that storm intensity and wind direction can strongly influence marine dispersal and landfall outcomes.

A Review and the Length-Weight Relationship of Bluefish, Pomatomus saltatrix (Linnaeus, 1766), Pisces: Pomatomidae, at the Marine Extractive Reserve (RESEX-Mar) of Arraial do Cabo, Rio de Janeiro State, Brazil

The bluefish, Pomatomus saltatrix (Linnaeus, 1766), the only representative of the Pomatomidae family, is a key fishing resource that represents a substantial part of the landings at RESEX-Mar of Arraial do Cabo-RJ. The species is broadly distributed throughout the continental shelf in tropical and warm temperate waters of the Atlantic, Pacific and Indian Oceans. It forms pelagic, large and fast moving shoals in relatively deep offshore waters, and draws close to the coast when temperatures reach from 12℃ to 15℃. Its displacement is conditioned to the movement of shoals of small fish such as herings; shrimp and squid, all of which are preyed upon. This work had the main purpose of evaluating the growth of bluefish through the distribution of length frequency (One-Way-ANOVA) and the Relationship between Total Length—TL (mm) and Total Weight—TW (g)-LWR; from daily data collections from March/2017 to March/2018. The analyzed specimens were obtained at fish markets of Arraial do Cabo-RJ and fish landings at the Fishermen’s Harbor of Praia dos Anjos. They were randomly sampled from fragmented cohorts of the local stock. A total of N = 2057 specimens were primary analyzed. TL values varied from 201 mm (minimum) in February/2018 to 915 mm (maximum) in September 2017. The average TL was of 541 mm and the average TW of 1428.5 g. The value of angular coefficient “b” in the potential flow was 2.6, and the value of “a” was 9E-05, expressed by the equation W = aLb for overall, where W = TW and L = TL. Values of W = 3E-05L2.7 were found for females and W = 2E- 05L2.8for males. Knowledge over their general biology is extremely important when it comes to knowing the ecology of this species for subsidize a future and adequate fishery management.

Lagrangian and Eulerian characterization of two counter‐rotating submesoscale eddies in a western boundary current

AbstractIn recent decades, high‐spatial resolution ocean radar and satellite imagery measurements have revealed a complex tangle of submesoscale filaments and eddies, in the surface velocity, temperature, and chlorophyll a fields. We use a suite of high‐resolution data to characterize two counter‐rotating, short‐lived eddies formed at the front between the warm East Australian Current (EAC) and temperate coastal waters (30°S, Eastern Australia). In this region, submesoscale filaments and short‐lived eddies are dynamically generated and decay at time scales of hours to days. Dominant cyclonic filaments of O(1) Rossby number formed along frontal jets and eddy boundaries, generating localized ageostrophic circulations at the submesoscale. Measurements of over‐ocean wind direction and surface currents from high‐frequency radars reveal the influence of the short‐term, small‐scale wind forcing on the surface circulation, enhancement of the horizontal shear, frontal jet destabilization, and the generation and decay of the cyclonic eddy. By contrast, the anticyclonic eddy formation was most likely associated with EAC mesoscale instability and anticyclonic vorticity. Lagrangian tracks show that surface particles can be temporarily trapped in the eddies and frontal convergent zones, limiting their transport. Mixing between EAC‐derived and coastal waters was increased along the frontal regions, and particles starting at the divergent regions around the eddies experienced significant dispersion at submesoscales. The cyclonic cold‐core eddy entrained high chlorophyll a shelf waters on its convergent side, suggesting spiral eddy cyclogenesis.

Non-native molluscan colonizers on deliberately placed shipwrecks in the Florida Keys, with description of a new species of potentially invasive worm-snail (Gastropoda: Vermetidae).

Artificial reefs created by deliberately sinking ships off the coast of the Florida Keys island chain are providing new habitat for marine invertebrates. This newly developing fouling community includes the previously reported invasive orange tube coral Tubastraea coccinea and the non-native giant foam oyster Hyotissa hyotis. New SCUBA-based surveys involving five shipwrecks spanning the upper, middle, and lower Florida Keys, show T. coccinea now also established in the lower Keys and H. hyotis likewise extending to new sites. Two additional mollusks found on the artificial reefs, the amathinid gastropod Cyclothyca pacei and gryphaeid oyster Hyotissa mcgintyi, the latter also common in the natural reef areas, are discussed as potentially non-native. A new species of sessile, suspension-feeding, worm-snail, Thylacodes vandyensis Bieler, Rawlings & Collins n. sp. (Vermetidae), is described from the wreck of the USNS Vandenberg off Key West and discussed as potentially invasive. This new species is compared morphologically and by DNA barcode markers to other known members of the genus, and may be a recent arrival from the Pacific Ocean. Thylacodes vandyensis is polychromatic, with individuals varying in both overall head-foot coloration and mantle margin color pattern. Females brood stalked egg capsules attached to their shell within the confines of their mantle cavity, and give rise to crawl-away juveniles. Such direct-developing species have the demonstrated capacity for colonizing habitats isolated far from their native ranges and establishing rapidly growing founder populations. Vermetid gastropods are common components of the marine fouling community in warm temperate and tropical waters and, as such, have been tagged as potentially invasive or with a high potential to be invasive in the Pacific Ocean. As vermetids can influence coral growth/composition in the Pacific and have been reported serving as intermediate hosts for blood flukes of loggerhead turtles, such new arrivals in the Florida Keys National Marine Sanctuary are of concern. Growing evidence indicates that artificial reefs can act as permanent way-stations for arriving non-natives, providing nurseries within which populations may grow in an environment with reduced competition compared to native habitats. Consequently, artificial reefs can act as sentinels for the appearance of new species. Ongoing monitoring of the developing molluscan fauna on the artificial reefs of the Florida Keys is necessary to recognize new invasions and identify potential eradication targets, thereby assuring the health of the nearby natural barrier reef.

True's beaked whale (Mesoplodon mirus) in Macaronesia.

The True’s beaked whale (Mesoplodon mirus, True 1913) is a poorly known member of the Ziphiidae family. Its distribution in the northern hemisphere is thought to be restricted to the temperate or warm temperate waters of the North Atlantic, while a few stranding records from the southern hemisphere suggest a wider and antitropical distribution, extending to waters from the Atlantic coast of Brazil to South Africa, Mozambique, Australia and the Tasman Sea coast of New Zealand. This paper (i) reports the first molecular confirmation of the occurrence of the True’s beaked whale at the southern limit of its distribution recorded in the northeast Atlantic: the Azores and Canary Islands (macaronesian ecoregion); (ii) describes a new colouration for this species using evidence from a whale with molecular species confirmation; and (iii) contributes to the sparse worldwide database of live sightings, including the first underwater video recording of this species and close images of a calf. Species identification was confirmed in two cases using mitochondrial DNA control region and cytochrome b gene markers: a subadult male True’s beaked whale that stranded in El Hierro, Canary Islands, in November 2012, and a subadult male found floating dead near Faial, the Azores, in July 2004. The whale that stranded in the Canary Islands had a clearly delimited white area on its head, extending posteriorly from the tip of the beak to cover the blowhole dorsally and the gular grooves ventrally. This colouration contrasts with previous descriptions for the species and it may be rare, but it exemplifies the variability of the colouration of True’s beaked whales in the North Atlantic, further confirmed here by live sightings data. The recording of several observations of this species in deep but relatively coastal waters off the Azores and the Canary Islands suggests that these archipelagos may be unique locations to study the behaviour of the enigmatic True’s beaked whale.

Diversity in the Globally Distributed Diatom Genus Chaetoceros (Bacillariophyceae): Three New Species from Warm-Temperate Waters

Chaetoceros is one of the most species rich, widespread and abundant diatom genera in marine and brackish habitats worldwide. It therefore forms an excellent model for in-depth biodiversity studies, assessing morphological and genetic differentiation among groups of strains. The global Chaetoceros lorenzianus complex presently comprises three species known to science. However, our recent studies have shown that the group includes several previously unknown species. In this article, 50 strains, mainly from high latitudes and from warm-temperate waters, were examined morphologically and genetically and the results compared with those of field studies from elsewhere. The strains clustered into five groups, two of which are formed by C. decipiens Cleve and C. mitra (Bailey) Cleve, respectively. Their species descriptions are emended based on samples collected close to the type localities. The three other groups are formed by new species, C. elegans sp. nov., C. laevisporus sp. nov. and C. mannaii sp. nov. Characters used to distinguish each species are: orientation of setae, shape and size of the apertures, shape, size and density of the poroids on the setae and, at least in some species, characters of the resting spores. Our aim is to cover the global species diversity in this complex, as correct species delineation is the basis for exploring biodiversity, distribution of organisms, interactions in the food web and effects of environmental changes.

Global population genetic dynamics of a highly migratory, apex predator shark.

Knowledge of genetic connectivity dynamics in the world's large-bodied, highly migratory, apex predator sharks across their global ranges is limited. One such species, the tiger shark (Galeocerdo cuvier), occurs worldwide in warm temperate and tropical waters, uses remarkably diverse habitats (nearshore to pelagic) and possesses a generalist diet that can structure marine ecosystems through top-down processes. We investigated the phylogeography and the global population structure of this exploited, phylogenetically enigmatic shark by using 10 nuclear microsatellites (n=380) and sequences from the mitochondrial control region (CR, n=340) and cytochrome oxidase I gene (n=100). All three marker classes showed the genetic differentiation between tiger sharks from the western Atlantic and Indo-Pacific ocean basins (microsatellite FST >0.129; CR ΦST >0.497), the presence of North vs. southwestern Atlantic differentiation and the isolation of tiger sharks sampled from Hawaii from other surveyed locations. Furthermore, mitochondrial DNA revealed high levels of intraocean basin matrilineal population structure, suggesting female philopatry and sex-biased gene flow. Coalescent- and genetic distance-based estimates of divergence from CR sequences were largely congruent (dcorr =0.0015-0.0050), indicating a separation of Indo-Pacific and western Atlantic tiger sharks <1million years ago. Mitochondrial haplotype relationships suggested that the western South Atlantic Ocean was likely a historical connection for interocean basin linkages via the dispersal around South Africa. Together, the results reveal unexpectedly high levels of population structure in a highly migratory, behaviourally generalist, cosmopolitan ocean predator, calling for management and conservation on smaller-than-anticipated spatial scales.

Population ecology of the invasive kelp Undaria pinnatifida towards the upper extreme of its temperature range

Understanding how the growth and life cycle of an invasive species relate to temperature is fundamental to predicting potential distribution and impacts. This paper investigates how the population ecology of the invasive kelp Undaria pinnatifida relates to water temperature in the warm-temperate waters of north-eastern New Zealand, one of the warmest water populations in the world and a region previously thought to be suboptimal for U. pinnatifida colonisation. Monitoring of U. pinnatifida on artificial structures over three growth seasons revealed an annual growth cycle, with one main recruitment event in winter ~2 months after water temperatures dropped below ~15 °C. Sporophyte growth rates peaked in late winter, density and sporophyte length peaked in spring and declined rapidly in summer. Density was strongly negatively related to water temperatures 8 weeks prior to sampling, whereas relative change in density was most strongly related to water temperature on the day of sampling, with largest declines when temperatures exceeded 20 °C. Densities remained low for varying periods depending on how long temperatures remained above 20 °C. Overall, sporophyte size and growth rates were comparable to those of cooler water populations, but the seasonal cycle was compressed into a shorter period when temperatures were cool enough for recruitment and growth. In warm-temperate and subtropical regions summer temperatures limit the seasonal presence while winter temperatures will ultimately determine the distribution of U. pinnatifida. The strong coupling between U. pinnatifida density and water temperature provides a basis for predicting the future distribution and related impacts of this species under changing climatic conditions.

Effects of light, temperature and stocking density on Halopteris scoparia growth

Halopteris scoparia (Linnaeus) Sauvageau is a cosmopolitan species, common in warm and cold temperate waters around Europe. Several studies have revealed the importance of the genus Halopteris to the nutraceutical and cosmetics industries due to its biological activities. The overexploitation of this natural resource must be prevented, both with sustainable harvesting and cultivation practices. This study investigated the effect of different stocking densities (SD) on the relative growth rate (RGR) and productivity of H. scoparia. A factorial experiment, using the best SD, was then run to test the combined effects of temperature and irradiance on the in vitro vegetative growth of H. scoparia. Overall, obtained results indicate H. scoparia appears to be a potential target species for aquaculture exploitation. It can grow in a wide range of temperatures (14 to 24 °C) providing irradiance is maintained under 150 μmol photons m−2 s−1 in order to restrain the development of epiphytes. Although promising, the methodologies adopted here require demonstration at larger-scale cultivation conditions, before moving to their effective implementation.

Distribution, habitat and movement of juvenile smooth hammerhead sharks (Sphyrna zygaena) in northern New Zealand

ABSTRACTThe smooth hammerhead shark, Sphyrna zygaena, occurs in warm temperate waters around the northern North Island of New Zealand. Commercial fishing records and research trawl survey data were used to determine their distribution. Highest catch rates were recorded in relatively sheltered bays and coastlines along the northeast coast of North Island. Neonate and juvenile sharks use shallow coastal waters and large harbours and estuaries as nursery areas up to an age of two years and total length of 150 cm. Five sharks were electronically tagged but two apparently died and three (137–160 cm total length) returned useful data. Two tagged sharks remained in or near the Bay of Islands for 6–55 days after tagging, moving extensively through the bay. A third shark moved about 155 km southeast in 250 days. That shark spent 70 days mostly shallower than 10 m (94% of time) with occasional dives to 40 m. Thereafter, it oscillated between the surface and depths of 60−80 m, with most time (55%) being spent at 40−60 m. Maximum recorded depth was 144 m.

A Pleistocene (MIS 5e) mollusk assemblage from Ezeiza (Buenos Aires Province, Argentina)

A fossil assemblage collected around 3.5 m amsl from Ezeiza, Buenos Aires province, have AMS 14C ages of ca. 33,000 to ca. 40,000 yr BP, whereas in the literature is a report of a conventional 14C age of >43,000 yr BP. An OSL age from the overlying deposit corresponds to ca. 22,000 yr. The samples contain marine fossils: mollusks, balanids and corals (Astrangia). La Coronilla (Uruguay, attributed to MIS 5e) is the locality most related to Ezeiza faunistically, despite is not the nearest one. In consequence, the relationship should be addressed to a more similar age and environment than others. The fauna indicates a higher water temperature than today. In Ezeiza exclusively cold water taxa are absent, and we found seven warm taxa with their southern distribution limit displaced northwards today, plus other six at their southern distribution limit. Around 60% of all the species and more than 70% of the individuals are of warm-temperate waters. In sum, although prima facie the numerical ages would locate the deposit in MIS3, faunistic, temperature, and height evidences show that the Ezeiza mollusk assemblage belong to MIS5e. A stronger than presently Brazil warm current, reaching Southern latitudes, may explain the changes in geographical ranges.

Evaluation of Chemical Defense and Chemical Diversity in the Exotic Bryozoan Amathia verticillata

The present investigation tests the effects against feeding by fishes of crude extracts obtained from eleven distinct populations of the bryozoan Amathia verticillata, an invasive species found globally in tropical to warm-temperate waters. Investigation of extracts from 11 populations of A. verticillata led to the identification and quantification of the known indole alkaloid 2,5,6-tribromo-N-methylgramine and isolation and identification of the new indole alkaloid, 2,6-dibromo-N-methylgramine. One extract of A. verticillata from Brazil significantly deterred feeding, while other extracts of A. verticillata from Florida significantly stimulated feeding by fishes, in field assays performed in Brazil. The same extracts of Florida samples showed variable effects on feeding, ranging from attraction to deterrence, in assays carried out in Florida. The absence of broad chemical defenses against feeding by fish suggests that the establishment of A. verticillata as an invasive species into new areas may be due to reasons other than defensive chemistry.

Differences in oscillatory whistles produced by spinner (Stenella longirostris) and pantropical spotted (Stenella attenuata) dolphins

AbstractAcoustic recordings of two closely related species, spinner dolphin (Stenella longirostris) and pantropical spotted dolphin (Stenella attenuata), were investigated from four different geographic locations: two in the Central Tropical Pacific, one in the Eastern Tropical Pacific and one in the Indian Ocean. The two delphinid species occur in tropical and warm temperate waters, with overlapping ranges. They produce very similar vocalizations, but at the same time their calls exhibit a certain degree of intraspecific variation among different geographic locations as has been observed in other delphinid species. Oscillatory whistles (whistles with at least two oscillations in their frequency contours) were identified and manually extracted from the recordings. Whistles with four or more maxima (oscillations) occurred only in spinner dolphins and they were present in all geographic regions investigated. In addition, the oscillatory whistles with two and three maxima were significantly more frequent in spinner than in spotted dolphins. The differences in oscillatory whistles for these two species seem to be consistent across study areas and therefore, could be used in addition to other whistle features to help distinguish between them.

Morphological and genetic variability among Ecklonia cava (Laminariales, Phaeophyceae) populations in Korea

Ecklonia cava Kjellman is a common kelp found in shallow subtidal in warm-temperate waters in the northwest Pacific Ocean. This species has shown substantial morphological variation along with subsistence in different locations and local environments. We quantified the magnitude of morphological variation of E. cava from six populations along ~700 km of coastline from Jeju Island to Dokdo in Korea. In addition, we examined genetic distance among the populations using random amplified polymorphic DNA (RAPD) analysis. Most morphological characteristics investigated were significantly different among locations. Multivariate analyses indicated two phenetically distinct groups (nearshore, sheltered vs. offshore, exposed), indicating wave exposure with turbidity are presumably major factors for the separation. With RAPD data, results of Nei's diversity (H) and AMOVA showed considerable variations in within- and between-populations. Pairwise <TEX>${\Phi}_{ST}$</TEX> and <TEX>$N_m$</TEX> values indicated moderate gene flow between the six locations. Results of Nei's analysis revealed three genetically distinct groups, not consistent with the morphological groupings, indicating that a time gap may exist between morphological and genetic variations. This study also suggests dispersal distance of this kelp may be longer than what is commonly thought and genetic similarity in the populations was largely reflected by the direction of ocean current rather than just geographical distance.

Marine palynology of the Oceanic Anoxic Event 3 (OAE3, Coniacian – Santonian) at Tarfaya, Morocco, NW Africa – transition from preservation to production controlled accumulation of marine organic carbon

The paper presented is the first comprehensive, fully quantitative, high resolution study of marine palynology from an OAE3 black-shale environment. It is based on 175 m core spanning the upper Turonian to lower Santonian at Tarfaya, Morocco, NW Africa, which has been sampled from centimetre to 3 m intervals. The results are integrated and discussed with lithology and geochemistry data to (1) distinguish between potential changes in production and preservation of total organic carbon (TOC) accumulation and (2) constrain the stratigraphic position of the Oceanic Anoxic Event 3 (OAE3).The succession is characterized by increased total organic carbon (TOC), varying between 1% and 19% (average about 6%). Distinct black-shale horizons of variable thickness appear episodically throughout the succession, with higher frequency in the late Turonian. Higher TOC contents do not strictly correlate to lithologic black-shales or peaks of a specific taxon of organic-walled algae. The palynomorph spectrum is strongly dominated by organic-walled algae, with the ratio of terrigenous sporomorphs to organic-walled algae (t/m index) varying between zero and 0.05 (average 0.01). The dominance of algal organic matter is corroborated by the prevalence of Type I kerogen identified using Rock-Eval pyrolysis. Dinocyst diversity is low, with the absolute taxa number varying from 7 to 27 between single samples. The peridinioid/gonyaulacoid ratio of dinocysts (p/g ratio) shows strong fluctuations, varying between 1 and 283 (average of about 100).The upper Turonian interval is dominated by Bosedinia spp., a dinocyst taxon formerly described as abundant only in lacustrine sediments from the Oligocene and Miocene of SE Asia. This dominance is episodically modified by the increase of the warm-temperate waters dinocysts fraction, here mainly represented by the genera Alterbidinium, Isabelidinium and Spinidinium. Within the Coniacian-Santonian, black-shale horizons are limited in number and are concentrated within the upper Coniacian to lower Santonian interval. The dinocysts show alternating, prominent peak abundances of Palaeohystrichophora spp. and the warm-temperate water dinocysts fraction, here mainly represented by the genera Trithyrodinium and Chatangiella. However, a final episode of increased proportions of Bosedinia spp. is confined to a 5 m thick black-shale horizon closely spanning the Coniacian-Santonian boundary.Changes in the ratio of total sulphur to total organic carbon (TS/TOC) reflect fluctuating oxygen contents of bottom waters throughout the late Turonian to Santonian. These are significantly parallelled by the alternation of dinocysts assemblages suggestive of enhanced upwelling and water column stratification respectively, probably reflecting changes in the mode of TOC accumulation. Accordingly, preservation largely prevails during the late Turonian interval and changes towards increased production within the Coniacian-Santonian. However, a final preservation-event is probably represented by the black-shale horizon closely spanning the Coniacian-Santonian boundary (top Dicarinella concavata foraminifera zone), which may reflect an episodic shutdown of a major upwelling cell. It is thus proposed, that the “culmination” of the OAE3 at Tarfaya may represent intermittent preservation of TOC within an otherwise high productivity environment related to a global cooling trend.

Paleobiogeography of the Danian molluscan assemblages of Patagonia (Argentina)

A detailed quantitative analysis of bivalves and gastropods reported from Danian marine rocks of Patagonia (Argentina) allowed the identification of three molluscan biogeographic units that, from north to south, are identified as the Rocaguelian, Salamancan, and Dorotean Bioprovinces. Molluscan assemblages comprise Cosmopolitan, Paleoaustral, Gulf Coastal Plain and Endemic genera, which collectively give this fauna a distinctive signature, preventing them to be considered as related to any other assemblages recorded in the high latitudes of the Southern Hemisphere. Results obtained through the present research support the idea that the Weddellian Province did not extend to Patagonia during Danian times, proving that the geographic isolation of this region during that interval was enough to allow the development of separate biogeographic units from other austral regions. Moreover, it is demonstrated that, although significant even in northern Patagonia, Paleoaustral taxa were not dominant elements of Danian faunas. Composition of the molluscan faunas reflects the presence of warm-temperate waters in the region, and records a latitudinal temperature trend with slightly higher values in northern Patagonia than in the south. In addition, a discussion of the age of the Paleocene faunas has been incorporated. The assemblages contained in the Dorotea formation (Austral Basin), Lefipán and Roca formations (Cañadón Asfalto Basin), and Salamanca formation (Cañadón Asfalto and Golfo San Jorge basins) have been placed in the early Danian, based on the correlation with the accurately dated molluscan faunas of the Roca formation exposed in the Neuquina–Colorado Basin, and that of the Sobral and López de Bertodano formations (Antarctica).

Not all fish are equal: functional biodiversity of cartilaginous fishes (Elasmobranchii and Holocephali) in Chile.

A review of the primary literature on the cartilaginous fishes (sharks, skates, rays and chimaeras), together with new information suggests that 106 species occur in Chilean waters, comprising 58 sharks, 30 skates, 13 rays and five chimaeras. The presence of 93 species was confirmed, although 30 species were encountered rarely, through validated catch records and sightings made in artisanal and commercial fisheries and on specific research cruises. Overall, only 63 species appear to have a range distribution that normally includes Chilean waters. Actual reliable records of occurrence are lacking for 13 species. Chile has a cartilaginous fish fauna that is relatively impoverished compared with the global species inventory, but conservative compared with countries in South America with warm-temperate waters. The region of highest species richness occurs in the mid-Chilean latitudes of c. 30-40° S. This region represents a transition zone with a mix of species related to both the warm-temperate Peruvian province to the north and cold-temperate Magellan province to the south. This study provides clarification of species occurrence and the functional biodiversity of Chile's cartilaginous fish fauna.