Subtropical Fauna Research Articles

Recent Progress in Taxonomic Studies, Biogeographic Analysis, and Revised Checklist of Reptiles in Indochina

The Indochinese Peninsula represents one of the key global biodiversity hotspots in Southeast Asia. The herpetofauna of Indochina (herein including Vietnam, Laos, Cambodia, and Thailand) currently (as by 10 August 2023) comprises 882 native and six invasive species of reptiles and is one of the richest in the world. About 40% of the Indochinese reptile species were discovered or recorded within the first two decades of the 21st century. We review the literature and our field data to assess all recent discoveries and taxonomic changes; we compile an annotated checklist of reptilian fauna of Indochina, including updated faunal lists for Vietnam and Thailand. Reptile species checklists for Laos and Cambodia are published for the first time. For each species we provide the following information: scientific name; recommended common name in English; information on type specimens; information on recognized subspecies; type locality; data on its distribution within Indochina and beyond; IUCN conservation status; taxonomic comments and the most important references. We review the distribution of each reptilian species across the 23 biogeographic subregions of Indochina, estimate the similarity among the regional faunas and evaluate their species richness and endemism. In total, we record 882 native reptile species belonging to three orders, 34 families and 163 genera; of them 408 species (46.3%) are endemic to Indochina. Comprising 512 known species, the reptilian fauna of Thailand is the richest (114 country endemics, 22.3%), followed by Vietnam with 496 species (157 endemics, 31.7%), Laos with 250 species (39 endemics, 15.6%), and Cambodia with 191 species (15 endemics, 7.9%). A cluster analysis of faunal similarity between the subregions revealed three major groupings, corresponding to the Sundaland fauna south of the Isthmus of Kra, the subtropical fauna of northeastern Indochina, and the tropical fauna of mainland Indochina. Within the latter grouping four clusters can be distinguished: (1) northern, central and southern Annamites, (2) western Indochinese subregions, (3) central-south Vietnam lowlands including the Bolaven Plateau and Cardamom Mountains, (4) and the depleted faunas of river deltas, coastal areas and offshore islands. We identify the Northern, Central and Southern Annamites, the Northwest Uplands of Vietnam, Laos and Thailand, Southern Tenasserim in Thailand as the major centers of reptilian diversity in Indochina. The highest number of Indochinese endemic reptilian species was recorded in Central-Southern Vietnam Lowlands, Northern Annamites, and Central Annamites. The analysis of reptilian distribution patterns suggests the presence of 20 clusters of species sharing similar distribution patterns across Indochina. Our results further underline the key role of Indochina as an important area for diversity and conservation of reptiles. Among 882 native species of Indochinese reptiles, 356 species (40.4%) are considered as Data Deficient (DD) or were Not Evaluated (NE) according to the IUCN Red List criteria, while 106 species (12.0%) were considered Vulnerable (VU), Endangered (EN) or Critically Endangered (CR), 17 species (1.9%) were considered to be Near Threatened (NT), and 403 species (45.7%) to be of the Least Concern (LC) status. Our work has implications for elaboration of further conservation efforts for Indochinese reptiles on regional and global levels, as well as for a better understanding of the biogeographic patterns of reptilian richness and endemism in Asia.

An update of the distribution of the stink bugs (Hemiptera: Pentatomidae) from Argentina

Pentatomidae is one of the largest families within Heteroptera, and it is represented in all zoogeographical regions, although the tropical and subtropical faunas are the most diverse. The field trips carried out in recent years in several localities in Argentina allow to update the distribution of stink bugs in the country. In this contribution, the genera Cataulax Spinola and Grazia Rolston, and the species Acledra breviscutata Breddin, Banasa peruana Thomas, Banasa dolabrata Thomas, Cataulax froeschneri Grazia, Campos & Becker, Grazia tincta (Distant), Mayrinia variegata (Distant), Mitripus acutus (Dallas), and Tylospilus peruvianus (Horváth), are recorded for the first time from Argentina. The characters used for the identification of these genera and species are provided. In addition, the geographic distribution of other 27 pentatomid species is expanded and new records of host plants are reported for Alveostethus pseudopolitus (Ruckes), Antiteuchus mixtus (Fabricius) and Pellaea stictica (Dallas)

The fossil record of the ocelot Leopardus pardalis (Carnivora, Felidae): a new record from the southern range of its distribution and its paleoenvironmental context

ABSTRACT Leopardus is a genus that, despite currently being widely distributed in South America, shows until now a fragmentary fossil record. Among Leopardus, L. pardalis is the largest species, having an historical range that includes tropical and subtropical habitats from southern U.S.A. to southern South America but, as usual in the ocelot lineage, fossil remains that can be interpreted with certainty are restricted to the Late Pleistocene of southern U.S.A. and Brazil. Here we present a new record (a fragment of right maxillary plus zygomatic with P4–M1; incomplete left mandible with the coronoid process, part of c1 alveolus and p3–m1; isolated right c1) from the Late Pleistocene of Arroyo Toropí, Corrientes province, Argentina. The bearing level was dated with Optically Stimulated Luminescence (OSL) to 98.4 ka (Marine Isotopic Stage, MIS 5c). Present environmental requirements of L. pardalis and climatic reconstructions carried out here suggest a compatible scenario with MIS 5 for this fossil, which is concordant with the associated dating (ca. 98.4 ka). Leopardus pardalis appears to be part of a subtropical fauna, with Tayassu pecari and Euphractus sexcinctus, which inhabited the region during warm and wet climatic events of MIS 5c. Phytoliths and other vertebrates are congruent with its presence, since the inferred conditions are similar to the present one. The new record is relevant not only because it is the first fossil record of the species for the Pleistocene of Argentina, but also because it is placed 1800 km south of the closest accurately identified published fossil.

Discovery of populations endemic to a marine biogeographical transition zone

AbstractAimBiogeographical transition zones are areas of overlap between the faunas of adjacent biogeographical entities. Particularly the well‐defined transition zones along linear coastlines are interesting natural laboratories to study dispersal and incipient speciation. Few studies have explored whether marine biogeographical transition zones harbour biodiversity that is distinct from that of the biogeographical entities they separate. The Wild Coast in eastern South Africa is a poorly studied transition zone between the region's warm‐temperate and subtropical faunas, and is generally considered to be an area of faunal overlap.LocationThe South African portion of the Western Indian Ocean.MethodsSequences of the DNA barcoding marker COI were generated from 306 estuarine sandprawns (Kraussillichirus kraussi) collected at 13 sites. Genetic structure and evolutionary history were assessed using a haplotype network and a Bayesian discrete phylogeographic analysis.ResultTwo populations were identified whose ranges are centred on the Wild Coast, a rare one in the northern portion and a more common one in the central and southern portion of this biogeographical transition zone. These populations are not closely related to each other, but descend from subtropical and warm‐temperate sister populations, respectively. Although genetic distances between populations were low, they exceeded within‐population distances, indicating the presence of a "barcoding gap."ConclusionsThis is the first study to indicate that the Wild Coast marine biogeographical transition zone is not merely an area of faunal overlap, and one of very few studies to have discovered genetically unique populations within a marine biogeographical transition zone. The Wild Coast may harbour additional unique biodiversity that remains to be discovered, including rare species that require protection. More research is required to understand how this environmentally dynamic marine biogeographical transition zone differs from the adjacent biogeographical provinces.

Mesoscale distribution and assemblage structure of fish larvae in the Kuroshio waters off eastern Taiwan

The mesoscale distribution of fish larvae and its relationships with oceanographic features were examined among six cruises from four seasons in the Kuroshio waters off eastern Taiwan between May 2003 and November 2004. A total of 389 taxa (including two morpho-types) of fish larvae belonging to 106 families and 204 genera were identified from the samples. Families with higher numbers of species were Myctophidae, Scombridae, Stomiidae, Paralepididae, and Gobiidae. Maurolicus japonicus (relative abundance, 7.8%), Vinciguerria nimbaria (7.4%), Sigmops gracilis (6.5%), Cyclothone alba (5.5%), and Diaphus stubby type (5.0%) were the five most abundant taxa. Fish larvae abundance was lower in February and August 2004 than in other cruises, but without spatial variation in distribution. Although the predominant species were similar among cruises, species number and diversity were higher in May 2003 and lower in August 2004. Two larval fish assemblages were distinguished, one containing mainly autumn, winter, and spring and the other mainly spring and summer collections. The taxonomically diverse larval fish assemblage demonstrated that the Kuroshio waters off eastern Taiwan are a major transition zone between tropical and subtropical faunas. These communities are enriched by northward advection of larvae and early juveniles of many tropical species into subtropical waters via the Kuroshio Current. In addition, offshore transport of neritic fish larvae also increased the diversity of the larval fish assemblage in Kuroshio waters. The distribution of fish larvae was related to oceanographic features, with surface salinity, chlorophyll, and food sources being correlated to the abundance of fish larvae.

Multiproxy studies of Early Miocene pedogenic calcretes in the Santa Cruz Formation of southern Patagonia, Argentina indicate the existence of a temperate warm vegetation adapted to a fluctuating water table

The Lower Miocene Santa Cruz Formation in southern Patagonia (Austral Basin, Argentina) contains several horizons of pedogenic calcretes, which record −17.5 myr old vegetation adapted to a shallow and fluctuating water table at paleolatitude of 56°S. To reconstruct the paleoenvironment, paleoclimate and paleoecosystem, we performed a multiproxy study of the calcretes examining abiotic and biotic components. The calcretes exhibit a variety of morphologies (horizontal and vertical rhizoliths, laminar structure, nodules, massive crusts), microfabrics (Beta- predominant over Alpha-microfabrics), and δ18O and δ13C values that fluctuate within each morphotype and throughout the analysed interval. Microfossils and phytoliths in the host material of the calcretes indicate fluctuating terrestrial, freshwater, and marine conditions, and record an ecosystem dominated by herbaceous plants and arboreal elements in association with a typical coastal “Santacrucian” vertebrate fauna. We propose that the calcretes developed in soils in a coastal/fluvial setting during pauses in floodplain aggradation that typically lasted between 8–25 ka and 400 ka years. Variable sedimentation rates in different parts of the coastal/fluvial floodplain, the fine texture of the host sediment, and the influence of a fluctuating water table also influenced the formation of the calcrete. A high water table in low relief areas of the floodplain created the conditions necessary to form a horizontally extended rhizolithic system that, jointly with the biotic proxy, can be correlated with a radicular pattern similar to the arboreal elements from coastal settings. Abiotic and biotic proxies of the studied interval attest to environmental fluctuations recorded at different scales that took place under temperate warm and subhumid climates with a marked rainfall seasonality, with a slight increase in the aridity towards the top of the studied interval. Under these conditions a subtropical fauna and a C3-dominated ecosystem developed coincident with the onset of the Mid-Miocene Climatic Optimum in Patagonia.

The palaeogeographic setting and the local environmental impact of the 130 ka Falconiera tuff-cone eruption (Ustica island, Italy)

This research focuses on the effects of the last eruption occurred at Ustica, which formed the Falconiera tuff-cone at around 130 ka BP in the north-eastern tip of the island. This eruption was mainly explosive and phreatomagmatic, with the emplacement of a series of pyroclastic-surge beds that determined the formation of an asymmetric tuff cone. This is the most easily recognizable Ustica volcanic edifice, although its north-eastern sector has been partially dismantled by the erosion. A section of the feeding conduit is exposed northward, showing the solidified lavas that fed the latest stages of the eruption. These were characterized by the formation of an intracrateric lava lake and a Strombolian scoria-fallout deposit. The eruption occurred during the Upper Pleistocene Marine Isotopic Substage 5.5, a warm period characterized by a high sea-level stand (6±3 m above the present sea level in stable areas) and the diffusion in the Mediterranean sea of subtropical flora and fauna. This eruption slightly modified the Ustica morphology, but impacted on both marine and terrestrial environments, burying beach deposits rich of mollusk shells (i.e. Strombus bubonius, Conus testudinarius, Brachidontes puniceus) , colonies of corals ( Cladocora caespitosa ) and subaerial plants ( Chamaerops humilis ). These organisms, found in some cases in their vital position, along with other lines of evidence, give information on the palaeogeography of this sector of the island at the time of the eruption, and on the local impact of this event on the environment.

Plio-Pleistocene climatic change had a major impact on the assembly and disassembly processes of Iberian rodent communities

Comprehension of changes in community composition through multiple spatio-temporal scales is a prime challenge in ecology and palaeobiology. However, assembly, structuring and disassembly of biotic metacommunities in deep-time is insufficiently known. To address this, we used the extensively sampled Iberian Plio-Pleistocene fossil record of rodent faunas as our model system to explore how global climatic events may alter metacommunity structure. Through factor analysis, we found five sets of genera, called faunal components, which co-vary in proportional diversity over time. These faunal components had different spatio-temporal distributions throughout the Plio-Pleistocene, resulting in non-random changes in species assemblages, particularly in response to the development of the Pleistocene glaciations. Three successive metacommunities with distinctive taxonomic structures were identified as a consequence of the differential responses of their members to global climatic change: (1) Ruscinian subtropical faunas (5.3–3.4 Ma) dominated by a faunal component that can be considered as a Miocene legacy; (2) transition faunas during the Villafranchian–Biharian (3.4–0.8 Ma) with a mixture of different faunal components; and (3) final dominance of the temperate Toringian faunas (0.8–0.01 Ma) that would lead to the modern Iberian assemblage. The influence of the cooling global temperature drove the reorganisation of these rodent metacommunities. Selective extinction processes due to this large-scale environmental disturbance progressively eliminated the subtropical specialist species from the early Pliocene metacommunity. This disassembly process was accompanied by the organisation of a diversified metacommunity with an increased importance of biome generalist species, and finally followed by the assembly during the middle–late Pleistocene of a new set of species specialised in the novel environments developed as a consequence of the glaciations.

Dynamics of abundance of eggs and larvae of common fish species in the central part of the Eastern Central Atlantic

Data on variation in the abundance of mass fish species at early stages of ontogenesis in different areas of the Eastern Central Atlantic in warm (June–November) and cold (December–May) seasons of 1994–2012 have been analyzed. The representatives of the mass species in the region are European pilchard Sardina pilchardus, common scad Trachurus trachurus, chub mackerel Scomber japonicus, round sardinella Sardinella aurita, Cunene horse mackerel T. trecae, and Atlantic bonito Sarda sarda. Within the economic zone of Morocco, variations in abundance of the representatives of the subtropical fauna (S. pilchardus, T. trachurus, and S. japonicus) at early stages of ontogenesis are similar over the entire area under study (32°–21°N). In the area of Mauritania (21°–16°N), variations in the abundance of the mass fish species of the tropical fauna (S. aurita, T. trecae, and S. sarda) at early stages of ontogenesis cannot be unambiguously compared with such variations in the area of Morocco because Senegal-Mauritanian populations of the species inhabit waters of different states and are not completely assessed by our surveys.

Descriptive and illustrated diagnosis of Ophiuroidea fauna (Echinodermata) in the shallow waters of North-eastern Brazil

In this study, we present descriptions, illustrations, comments, and bathymetric and geographic distributions of the brittle star species related to the estuary region of Camamu Bay, located in the State of Bahia, Brazil. The brittle star fauna lives on biological substrates, sand bottoms, mud and rubble in the Camamu Bay and comprises 12 species divided into five families. Almost all of them are common in the tropical and subtropical fauna of the regions of shallow water.Ophiophragmus filograneusis reported for the first time in Bahia, and nine other species are recorded for the first time in Camamu Bay:Amphipholis januarii, Amphipholis squamata, Ophiophragmus filograneus, Ophiostigma isocanthum,Ophioderma cinerea, Ophioderma januarii, Ophiactis lymani, Ophiactis savignyi andOphiocoma echinata.The results suggest that the ophiuroid assemblages are strongly affected by marine currents as well as by different kinds of bottom substrate.

Trematode communities in cockles (Cerastoderma edule) of the Ria de Aveiro (Portugal): Influence of inorganic contamination

This work aims to assess the trematode parasites infecting the edible cockle Cerastoderma edule, collected in the Ria de Aveiro lagoon, one of the most relevant biodiversity hotspots of the Western Iberia, and evaluate the relationship between the observed patterns and environmental descriptors. A total of 11 of the 16 trematode species known to infect C. edule were identified, including Himasthla continua and Psilostomum brevicolle as new occurrences in this lagoon. Parvatrema minutum was the most abundant and dominant species. Species richness and prevalence were high. The relationship between trematode species abundance, intensity and prevalence, and also environmental variables, showed that most parasites preferred muddy sand areas with euhaline conditions in opposition to areas with contamination and/or distant from the lagoon entrance. This study highlighted the good ecological status of the ecosystem and the transitional biogeographic characteristics of the western Portuguese coast where northern and subtropical faunas can coexist.

Global diversity and endemism in Early Silurian (Aeronian) brachiopods

Silurian brachiopods of Middle Llandovery (Aeronian) ages are reviewed, and 215 genera are identified here, compared with 109 in the preceding Early Llandovery (Rhuddanian), indicating a recovery-radiation interval after the end-Ordovician mass extinction. The chief regions in which they are found are the continents of South China, Avalonia-Baltica, Laurentia and Siberia, which were all at tropical latitudes with the exception of Avalonia. In addition, the very large superterrane of Gondwana, although with patchy brachiopod distribution, included temperate faunas, as well as subtropical faunas (in Iran and Afghanistan). Aeronian brachiopods greatly increased in diversity, with dominance of four major groups: orthides and strophomenides (which had flourished previously in the Rhuddanian), pentamerides and atrypides (which became dominant in the Aeronian), and many newly evolved taxa, and occupied deeper water and wider ecological niches (level bottom and reef) than those in the Rhuddanian. Each of the continents has some endemic genera, but there is a greater proportion of them in South China, where some groups (such as the pentamerides and atrypides) are more diverse and others, such as the orthides, are much less common than elsewhere. Affinity indices (AI) show that two megaunits can be recognized: South China and Avalonia-Baltica-Laurentia (ABL); Siberia seems to have been loosely connected with ABL and even more loosely to South China presumably because of its geographical separation in the Northern Hemisphere. The separation of South China from the other megaunits is further supported by cluster analysis.

Diversity, distribution and ecology of benthic molluscan communities on the Portuguese continental shelf

The diversity, ecology and distribution patterns of the Portuguese continental shelf malacofauna and its relationship with abiotic factors were studied from samples covering the western and the southern coast. A total of 2544 specimens were identified corresponding to 169 taxa, mostly bivalves (62% of the total taxa). Abra alba was the most abundant and the most frequent species. The alpha diversity ranged from one species to 21 spp. 0.1m−2. The highest abundance and diversity were obtained in coarser sediments. Multivariate analysis based on the abundance data identified five major malacological groups: (a) Angulus pygmaeus and Thracia villosiuscula in the coarser sediments of the western inner and mid shelf; (b) Calyptraea chinensis and Leptochiton cancellatus in the heterogeneous and organically enriched sediments of the southern shelf; (c) Angulus fabula, Spisula subtruncata and Pharus legumen in the near shore exposed fine sands; (d) A. alba in muddy fine sands, mainly in the northwestern shelf and (e) Saccella commutata in the southwestern deeper shelf. The malacofauna could be used as a proxy for the major benthic communities known to occur in this area, except in muddy patches, where molluscs were absent or low abundant. Median grain-size, gravel content, depth and hydrodynamic regime were the environmental factors best related to the malacofauna spatial distribution patterns. This study sets the first record of Astarte borealis, Leptochiton asellus, Mercenaria mercenaria and Montacuta phascolionis in the Portuguese shelf and the most northern limit for Anadara polii, Glycymeris nummaria, and Leptochiton algesirensis along the northwestern shelf. This study also gives new ecological insights for several species, in terms of bathymetric range distribution, as well as habitat type and highlighted the transitional characteristics of the molluscan communities from this particular northeastern Atlantic area where boreal, temperate and subtropical faunas can coexist.

Soft-bottom Portuguese continental shelf polychaetes: Diversity and distribution

This study fulfills a gap in the knowledge of the annelid polychaete fauna from most of the Western Iberian coast, a particular biogeographic area where boreal, cold temperate, warm temperate and subtropical faunas can co-occur. A total of 145 samples covering the entire Portuguese continental shelf were analyzed to study the diversity and spatial distribution of the polychaetes and to discuss the relationship between biological and environmental data. A total of 19,731 annelid polychaetes were identified corresponding to 319 species and belonging to 49 families. The species Mediomastus fragilis, Polygordius appendiculatus and Ampharete finmarchica were the most abundant and Ampharete finmarchica, Lumbrineris lusitanica and Aponuphis bilineata the most frequent. Abundance per site reached 620 individuals and alpha diversity ranged from 1 species to 65 spp. 0.1m−2. A total of 26 species were firstly recorded in the Portuguese shelf, one of them new for the Iberian coasts. A multivariate analysis based on the abundance of polychaetes revealed six affinity groups: (a) coarse sediments characterized by several species, mostly of the Order Phyllodocida, such as Pisione remota, Goniadella gracilis, Glycera lapidum, Sphaerosyllis bulbosa and Pisione parapari; (b) near shore shelf fine sands dominated by Magelona johnstoni, Magelona filiformis and Sigalion mathildae; (c) northwestern deep muddy sands characterized by Prionospio fallax, Lagis koreni and Owenia fusiformis; (d) southwestern deep muddy sands with Aphelochaeta sp., Galathowenia oculata and Monticellina heterochaeta; (e) southern midshelf muddy sands characterized by Euchone rubrocincta, Prionospio multibranchiata and several southern species; and (f) muds dominated by Nepthys incisa and characterized by Sternaspis scutata, Heteromastus filiformis, Ninoe armoricana and Glycera unicornis. Sediment grain-size and organic matter were the variables best related to the benthic polychaete spatial distribution patterns along the Portuguese continental shelf.

Diversity and spatial distribution patterns of the soft-bottom macrofauna communities on the Portuguese continental shelf

This study presents a comprehensive assessment of the diversity and spatial distribution of the soft-bottom benthic macrofauna communities along the Portuguese continental shelf and discusses the relationship between biological and environmental data. A total of 145 sites were sampled using a 0.1m2 Smith–McIntyre grab covering the whole west and south coast of Portugal, at depths ranging 13 and 195m. More than 30,000 specimens were identified corresponding to 737 taxa, mostly annelids (43% of the total taxa). The most frequent species were Ampharete finmarchica, Ampelisca sp. and Lumbrineris lusitanica while the most abundant were Mediomastus fragilis, Polygordius appendiculatus and Ampharete finmarchica. Abundance ranged between 7 and 1307 specimens per 0.1m2 and alpha diversity reached a maximum of 96 taxa per 0.1m2. Gravel sediments, and shallow and sheltered areas presented higher diversity values than mud sediments and deeper sites. Six major benthic assemblages were identified: (a) Coarse sediments, mostly located on the western shelf, with Protodorvillea kefersteini, Pisione remota, Angulus pygmaeus and several other interstitial species; (b) near shore fine sands with Magelona johnstoni, Urothoe pulchella and Angulus fabula; (c) Abra alba community in northwestern deep muddy sands; (d) Southwestern very deep muddy sands characterized by Galathowenia oculata, Lumbrinerides amoureuxi and other burrowers and tubicolous polychaetes; (e) Euchone rubrocincta, Nematonereis unicornis and other warmer water species in muddy sands of the southern and sheltered shelf; and (f) muds dominated by Sternaspis scutata, Heteromastus filiformis and Psammogammarus caecus. Sediment grain-size, organic matter, depth and hydrodynamic regime were the variables best related to the macrofauna distribution patterns, highlighting the transitional characteristics of this northeastern Atlantic area, where northern and subtropical faunas can coexist.

Highly diverse molluscan assemblages of Posidonia oceanica meadows in northwestern Alboran Sea (W Mediterranean): Seasonal dynamics and environmental drivers

The seasonal dynamics of the molluscan fauna associated with the westernmost populations of the Mediterranean seagrass Posidonia oceanica, has been studied throughout an annual cycle in the northwestern coasts of the Alboran Sea. Samples were collected seasonally (5 replicated per season) using a non-destructive sampling technique (airlift sampler) on quadrats of 50 × 50 cm at 2 sites located 7 km apart. Several environmental variables from the water column (temperature, chlorophyll a), the sediment (percentage of organic matter) and the seagrass meadows (shoot density, leaf height and width, number of leaves per shoot) were also measured in order to elucidate their relationships with the dynamics of the molluscan assemblages. In these meadows, a total of 17,416 individuals of molluscs were collected, belonging to 71 families and 171 species, being Rissoidae, Pyramidellidae and Trochidae the best-represented families, and Mytilidae, Nassaridae and Trochidae the dominant ones in terms of abundance. The assemblages were dominated by micro-algal grazers, filter feeders and ectoparasites (including those feeding on sessile preys). The species richness and the abundance displayed significant maximum values in summer, whereas evenness and diversity displayed maximum values in spring, being significant for the evenness. Both abundance and species richness values were positively correlated to seawater temperature and percentage organic matter, only for the latter, and negatively to leaf width. Significant seasonal groupings were obtained with multivariate analyses (MDS, Cluster, ANOSIM) using qualitative and quantitative data that could be mainly related to biological aspects (i.e. recruitment) of single species. The molluscan assemblages are influenced by the biogeographical location of the area (Alboran Sea), reflected in the absence or scarcity of most Mediterranean species strictly associated with P. oceanica (e.g. Tricolia speciosa, Rissoa ventricosa) and by the occurrence of subtropical fauna (e.g. Ungulina cuneata). The patchiness of the meadows, intercalated in other habitats like photophilous algae, and the strong hydrodynamism resulting from the unusually shallow setting, may promote the movement of species between these habitats and the seagrass and therefore enhance the species richness. This large faunistic list for the molluscan fauna associated with P. oceanica is therefore different than those observed in other meadows, and highlights the conservation value of these fragmented meadows located in their western distributional limit.

Seasonal and interannual variation of the ichthyoplankton off the coast of Northern Morocco

Changes in the qualitative and quantitative composition of the ichthyoplankton off the coast of Northern Morocco (36–28° N) are analyzed in different seasons of 1994–2008. Pelagic eggs and larvae of over 80 fish species belonging to 57 families are recorded. In cold periods at the Morocco coast, there is maximum spawning of fish belonging to the subtropical (Mediterranean-Atlantic) fauna, the dominant of which are European pilchard Sardina pilchardus, common scad Trachurus trachurus, and Atlantic mackerel Scomber japonicus. In warm periods, in addition to the aforementioned species, the ichthyopankton often comprises eggs and larvae of fish form the tropical fauna. Among the latter are round sardinella Sardinella aurita and West-African mackerel T. trecae dominate. The spawning biomass of principal commercial fish is also calculated by the quantity of eggs laid by females.

Seasonal and interannual variation of ichthyoplankton off the coast of the Moroccan Sahara

Changes in the qualitative and quantitative composition of ichthyoplankton off the coast of the Moroccan Sahara (21–28° N) in different seasons of 1994–2007 are analyzed. In this region, the pelagic eggs and larvae of over 100 fish species belonging to 62 families have been recorded. In cold periods, off the coast of the Moroccan Sahara there is peak in the spawning of fish of the subtropical fauna. The majority of them are European pilchard Sardina pilchardus, common scad Trachurus trachurus, and Atlantic mackerel Scomber japonicus. In warm periods there is intensive spawning of fish of the tropical fauna. Among them, dominants are round sardinella Sardinella aurita, West-African scad Trachurus trecae, and Atlantic bonito Sarda sarda. The spawning biomass of principal commercial fish is calculated by the quantity of eggs laid by females. The environmental factors are indicated that influence the fluctuation of abundance and distribution of ichthyoplankton in the region under consideration.

Pliocene climate and seasonality in North Atlantic shelf seas

This paper reviews North Atlantic shelf seas palaeoclimate during the interval 4-3Ma, prior to and incorporating the 'Mid-Pliocene warm period' (ca 3.29-2.97Ma). Fossil assemblages and stable isotope data demonstrate northwards extension of subtropical faunas along the coast of the Carolinas-Virginia (Yorktown and Duplin Formations) relative to the present day, suggesting a more vigorous Florida Current, with reduced seasonality and warm water extending north of Cape Hatteras (reconstructed annual range for Virginia 12-30 degrees C). This interpretation supports conceptual models of increased meridional heat transport for the Pliocene. Sea temperatures for Florida (Lower Pinecrest Beds) were similar to or slightly cooler than (summers 25-27 degrees C) today, and were probably influenced by seasonal upwelling of cold deep water. Reduced seasonality is also apparent in the Coralline Crag Formation of the southern North Sea, with ostracods suggesting winter sea temperatures of 10 degrees C (modern 4 degrees C). However, estimates from Pliocene bivalves (3.6-16.6 degrees C) are similar to or cooler than the present day. This 'mixed' signal is problematic given warmer seas in the Carolinas-Virginia, and climate model and oceanographic data that show warmer seas in the 'Mid-Pliocene' eastern North Atlantic. This may be because the Coralline Crag Formation was deposited prior to peak Mid-Pliocene warmth.

Assemblages of megabenthic gastropods from Uruguayan and northern Argentinean shelf: Spatial structure and environmental controls

We analyzed the structure of the megabenthic gastropod assemblages on the Uruguayan and northern Argentinean shelf and slope. Our analysis determined that there are two major biologically distinct assemblages which occurred in a 210,000 km 2 area showing conspicuous environmental gradients and large frontal areas: (a) an assemblage associated with the zone under the influence of the freshwater discharge of Río de la Plata and the shallow waters of the inner shelf and (b) an assemblage associated with marine zone in the outer shelf, which includes Magellanic (Subantarctic) and subtropical faunas. A multivariate analysis demonstrated a significant correlation between the environmental and biological matrix. This evidence suggests a noticeable effect of the physical environment on the spatial structure of the assemblage. We suggest that the current distribution patterns are caused by two different processes operating together: while processes operating at ecological time scales (e.g. differential tolerances to salinity and depth) determine most of the structure observed at the inner shelf, the presence of two contrasting water masses over the outer shelf determine a biogeographic boundary for the benthic fauna, linked to shifting climatic factors influencing species niche dynamics over evolutionary time scales. Thus, at the spatial scale here considered, ecological and historical processes must be considered when attempting to understand which factors determine the current structure of benthic assemblages at regional scales.