Age and growth of a sub-Antarctic notothenioid, Patagonotothen ramsayi (Regan 1913), from the Falkland Islands

The Falklands’ rockcod Patagonotothen ramsayi was aged successfully using whole and sectioned otoliths. Marginal increment analysis showed that one opaque and one translucent zone were laid down each year. Counting daily rings in juvenile fish and back calculating to their assumed hatch dates validated the first annulus. Readings taken from scales and otoliths showed good agreement with no significant difference between them (P>0.05). Inter- and intra-reader comparisons also showed good agreement. The maximum estimated age was found to be 14 years and the calculated von Bertalanffy growth curve L _T =33.77(1−e ^{−0.25year(t+1.07)}) showed that P. ramsayi is a relatively slow growing fish that attains 5–6 cm L _T in its first year and after which grows approximately 3 cm per year until 4 years. Males seemed to have a slightly lower growth rate but attained a greater maximum size than females. The formation of annuli in the otoliths of P. ramsayi seems to coincide with periods of high reproductive activity with both peaks in GSI and the prevalence of translucent margins occurring in July.     

Reproductive biology of Patagonotothen ramsayi (Regan, 1913) (Pisces: Nototheniidae) around the Falkland Islands

The reproductive biology of one of the most abundant notothenioids, Patagonotothen ramsayi, was investigated between February 2003 and November 2004 on the Falkland and Patagonian Shelves (Southwest Atlantic). Male and female P. ramsayi were mature at 27.6 and 24.8 cm L _T, respectively. P. ramsayi is a total spawner, with a total fecundity ranging between 24,300 and 76,700 eggs. Spawning occurs on the shelf breaks between June and August with the peak in gonado-somatic indices in June. Analysis of length frequency distributions over the year and sex ratios of mature fish during the spawning season may indicate the presence of a nesting and nest guarding behaviour in male fish, similar to other rockcods. Features of its reproductive strategy, which enabled P. ramsayi to dominate the medium-sized demersal fishes on the Patagonian shelf are discussed and compared with those of other nototheniids and cottid sculpins from the Northern Hemisphere.     

New species of Acanthochondria (Copepoda: Chondracanthidae) infecting the longtail southern cod, Patagonotothen ramsayi (Perciformes: Nototheniidae), from Patagonian waters, Argentina

Acanthochondria lilianae n. sp. (Copepoda: Chondracanthidae) is described and illustrated based on specimens of both sexes collected from inner surface of the operculum of the longtail southern cod, Patagonotothen ramsayi (Regan) (Perciformes: Nototheniidae), from the Patagonian Shelf, Argentina (42-48°S, 60-63°W). Acanthochondria lilianae n. sp. is characterized by the combination of a Type B-III antennule and Type A leg 2, in addition to both the cephalosome and the trunk being wider than long. The new species most closely resembles Acanthochondria incisa Shiino, 1955, Acanthochondria ophidii (Kr?yer, 1863), Acanthochondria priacanthi Shiino, 1964, and Acanthochondria tasmaniae Heegaard, 1962, but differs from these species in the general measurements and proportions of the body, shape and size of head, shape and size of genitoabdomen, and fine details of appendages such as the armature of antennule, ornamentation of both pairs of legs, number of teeth on mandible and maxilla, and ornamentation on maxilliped. This is the first Acanthochondria species recorded from a nototheniid and the second southernmost record of a species of this genus in the southwestern Atlantic Ocean.     

Diet and daily ration of two nototheniid fish on the shelf of the sub-Antarctic Prince Edward Islands

The seasonal dietary composition and estimates of daily consumption rate of Lepidonotothen larseni and Gobionotothen marionensis juveniles were obtained for the first time using fish collected near sub-Antarctic Prince Edward Islands during April 1999–2003. The diet of L. larseni consisted mainly of pelagic prey, with copepods and arrow worms making up the most significant prey groups and accounting for 46% and 40% of prey mass, respectively. The diet of G. marionensis was more diverse than that of L. larseni and was composed mainly of benthic prey, including bottom-dwelling decapods (Nauticaris marionis) and sedentary polychaetes, which accounted for 54% and 30% of prey mass, respectively. During the present study, dietary overlap between juveniles of L. larseni and G. marionensis was very low (<5%) indicating that competition for food resources between them was negligible. They not only relied on different prey species, both also exhibited different diel feeding regimes. Daily consumption rate of L. larseni and G. marionensis juveniles was estimated to be 4.5% and 5.2% of body dry mass, respectively. Stomach contents and stable isotope analyses suggested, that both L. larseni and G. marionensis occupy the forth-trophic level of the sub-Antarctic food web but depend mainly on allochthonous and autochthonous (kelp derived) organic matter, respectively.     

Spawning, egg development and early ontogenesis in rock cod Patagonotothen ramsayi (Regan, 1913) caught on the Patagonian Shelf and maintained in captivity

Rock cod Patagonotothen ramsayi (Regan, 1913) is one of the most abundant fish of the family Nototheniidae inhabiting the Patagonian Shelf and upper Slope in the southwest Atlantic. Recently, P. ramsayi became an important commercial species around the Falkland Islands with annual catch of 60,000–75,000 t. The present study aimed to reveal previously unknown aspects of reproductive biology of P. ramsayi during the first successful maintenance of adults for more than a year in an aquaculture facility with running seawater. The fish spawned at the end of austral winter. During spawning, males changed their coloration dramatically, occupied artificial shelters on the bottom and showed aggressive territorial behaviour. Egg masses were light-yellow to light-orange irregular spongiform. They were negatively buoyant, but located outside shelters and were ignored by males. Egg diameters varied between 2.1 and 2.3 mm, and the number of eggs per egg mass ranged from 26,800 to 123,400. Embryogenesis lasted 28–32 days. Total lengths of newly hatched larvae ranged from 6.2 to 6.7 mm. The yolk sac feeding period lasted approximately 11 days, during which the larvae showed negative phototaxis. One-month-old larvae attained 8.8–9.0 mm in length. This study confirms that P. ramsayi exhibit the reproductive strategy typical for nototheniid species occupying low-latitude peripheries of their distributional range, characterised by a combination of r-features (small eggs and larvae, high fecundity) and K-features (territorial behaviour and possible nest guarding).     

An impact of seasonal squid migrations and fishing on the feeding spectra of subantarctic notothenioids Patagonotothen ramsayi and Cottoperca gobio around the Falkland Islands

Seasonal changes in the diet of two abundant notothenioid fishes, rock cod Patagonotothen ramsayi (Nototheniidae) and frogmouth Cottoperca gobio (Bovichthidae) were studied on the Falkland Island shelf. The rock cod is a near-bottom browser, feeding mostly on gelatinous and crustacean plankton. The diet of juveniles [10–16 cm total length (TL)] includes mostly copepods in summer and comb jellies Mnemiopsis leydyi in winter. Adult rock cod (17–34 cm TL) in summer consumed mainly plankton, with comb jellies and salps being of primary importance. In winter they mainly took benthos, primarily ophiuroids and lobster krill ( Munida spp.), and the comb jelly. During the fishing season, rock cod also scavenge on fishing discards. The frogmouth is a benthic ambush predator; both small (11–30 cm) and large (31–80 cm) representatives feed on the rock cod throughout the year. During the seasonal offshore migration of the squid Loligo gahi (June–August), this prey predominated in the large frogmouth diet, with crab, Peltarion spinosulum , of secondary importance. The region is seasonally exploited by the squid trawl fishery. As the fishing season commences (August–September), discarded rock cod also becomes an important food item for the frogmouth. Seasonal offshore migrations of L. gahi into the common depth range of both notothenioids have a significant direct (change in the C. gobio diet) and indirect (scavenging on fishing discards and targeting bottom scavengers by P. ramsayi and C. gobio during the squid fishing) impact on their diets over the Falkland shelf. The niche breadth of rock cod varied from 2.63 to 3.21 and that of frogmouth varied from 2 to 6.29, depending on fish size and season.     

Moss-inhabiting diatom communities from Heard Island,sub-Antarctic

In this paper, we list 192 diatom taxa, collected from bryophyte samples from Heard Island (52°05S, 73°30E). The Heard Island diatom flora shows a marked similarity to those of the Crozet and Kerguelen archipelagos, and is quite dissimilar to the moss-dwelling diatom flora of Macquarie and Amsterdam Island. Based on species composition, three main groups of samples could be discerned. Each group represents a different habitat. Samples dominated by Diadesmis ingeae, Pinnularia borealis and several Psammothidium species seem to prefer the driest habitats. A special form of this community was found in shaded areas. Samples from wet habitats such as flush areas and pools were dominated by species such as Adlafia bryophila, Sellaphora tumida, Fragilaria capucina and Planothidium lanceolatum. An intermediate group was observed in more acid, but terrestrial, conditions, characterised by Eunotia paludosa and Chamaepinnularia soehrensis var. muscicola. These community patterns are similar to those found on other sub-Antarctic islands, and we suggest that a group of typical sub-Antarctic species and communities exists.     

Vegetation of the McDonald Islands, sub-Antarctic

The McDonald Islands (53°03^′S, 72°36^′E) are situated in the southern Indian Ocean, approximately 43 km west of Heard Island. These sub-Antarctic islands comprise McDonald Island itself, measuring ca.1 × 2 km, and two much smaller rocky outcrops, Flat Island and Meyer Rock. Five species of vascular plant occur on the islands. Only four species of moss were found, no hepatics, and eight species of lichen, together with algal and fungal species. Phanerogamic vegetation, comprising grassland and cushion-carpet herbfield, covers about one-third of the main island. Elsewhere, vegetation is absent or restricted to cryptogamic species. The distribution and occurrence of vegetation are strongly influenced by salt deposition, exposure to wind, substrate stability and biotic influences, particularly the very large assemblages of sea birds. The species-depauperate McDonald Islands are unique and have suffered negligible human impact. A management plan has been prepared; its implementation will be assisted by the information in this paper. The islands' protection will be further enhanced by an affirmative final decision on the current proposal for World Heritage Listing of Heard and the McDonald Islands. Received: 15 November 1996 / Accepted: 24 March 1997     

Boreascotia megavesicula n. g., n. sp. (Digenea: Hemiuridae: Lecithochiriinae) in the nototheniid fish Lepidonotothen macrophthalma (Norman) from the sub-Antarctic Atlantic

Boreascotia megavesicula n. g., n. sp. is described from the intestine of the fish Lepidonotothen macrophthalma from the North Scotia Ridge, Sub-Antarctic, Atlantic Ocean. The new genus has an ecsoma, placing it in the family Hemiuridae, and a distinct prostatic vesicle, placing it in the subfamily Lecithochiriinae, but is distinct from the other members of the subfamily in having an elongate, tubular seminal vesicle, which reaches well into the hindbody and overlaps the anterior testis.     

Biological traits of Xylella fastidiosa strains from grapes and almonds

Xylella fastidiosa is a xylem-limited bacterium that causes various diseases, among them Pierce's disease of grapevine (PD) and almond leaf scorch (ALS). PD and ALS have long been considered to be caused by the same strain of this pathogen, but recent genetic studies have revealed differences among X. fastidiosa isolated from these host plants. We tested the hypothesis that ALS is caused by PD and ALS strains in the field and found that both groups of X. fastidiosa caused ALS and overwintered within almonds after mechanical inoculation. Under greenhouse conditions, all isolates caused ALS and all isolates from grapes caused PD. However, isolates belonging to almond genetic groupings did not cause PD in inoculated grapes but systemically infected grapes with lower frequency and populations than those belonging to grape strains. Isolates able to cause both PD and ALS developed 10-fold-higher concentrations of X. fastidiosa in grapes than in almonds. In the laboratory, isolates from grapes overwintered with higher efficiency in grapes than in almonds and isolates from almonds overwintered better in almonds than in grapes. We assigned strains from almonds into groups I and II on the basis of their genetic characteristics, growth on PD3 solid medium, and bacterial populations within inoculated grapevines. Our results show that genetically distinct strains from grapes and almonds differ in population behavior and pathogenicity in grapes and in the ability to grow on two different media.     

Comparative study of the erythrocytes and haemoglobins in nototheniid fishes from Antarctica

The blood of seven Antarctic nototheniid species and representatives from three other families contained low haemoglobin concentrations compared with non-polar marine teleosts. Haematocrit values were slightly lower than values from other teleosts, while haemoglobin and erythrocyte counts were substantially reduced by comparison. Interspecific variation in haemoglobin concentration seemed to be a function of activity level. Mean corpuscular haemoglobin concentration of all Antarctic species was strikingly low by comparison with species from lower latitudes and was not correlated with the habits of the species. Haemoglobin componentry was compared using celluslose-acetate electrophoresis and, unlike many temperate species, only one major haemoprotein was isolated from each benthic species, but four components were evident in the pelagic species Trematomus borchgrevinki . The possible functional significance of these findings was discussed in relation to the ecology of each species.     

Biological traits of European pond macroinvertebrates

Whilst biological traits of river macroinvertebrates show unimodal responses to geographic changes in habitat conditions in Europe, we still do not know whether spatial turnover of species result in distinct combinations of biological traits for pond macroinvertebrates. Here, we used data on the occurrence of 204 macroinvertebrate taxa in 120 ponds from four biogeographic regions of Europe, to compare their biological traits. The Mediterranean, Atlantic, Alpine, and Continental regions have specific climate, vegetation and geology. Only two taxa were exclusively found in the Alpine and Continental regions, while 28 and 34 taxa were exclusively recorded in the Atlantic and Mediterranean regions, respectively. Invertebrates in the Mediterranean region allocated much energy to reproduction and resistance forms. Most Mediterranean invertebrate species had narrow thermal ranges. In Continental areas, invertebrates allocated lesser energy to reproduction and dispersal, and organisms were short lived with high diversity of feeding groups. These characteristics suggest higher resilience. The main difference between ponds in the Alpine and Atlantic regions was their elevation. Alpine conditions necessitate specific adaptations related to rapid temperature fluctuations, and low nutrient concentrations. Even if our samples did not cover the full range of pond conditions across Europe, our analyses suggest that changes in community composition have important impacts on pond ecosystem functions. Consistent information on a larger set of ponds across Europe would be much needed, but their low accessibility (unpublished data and/or not disclosed by authors) remains problematic. There is still, therefore, a pressing need for the incorporation of high quality data sets into a standardized database so that they can be further analyzed in an integrated European-wide manner.     

Biological traits of stream macroinvertebrates from a semi-arid catchment: patterns along complex environmental gradients

1. The relationships between biological traits of macroinvertebrates and environmental characteristics were investigated in streams with contrasting physical, chemical or landscape level attributes. We used an ordination technique, RLQ analysis, which links an environmental table (R) with traits table (Q) through an abundance table (L) to investigate the relationship between habitat characteristics and biological traits.
2. A major environmental axis explaining the distribution of species and their distinctive biological features was obtained. This axis included variables of anthropogenic pressure (agricultural and urban uses) and natural variability (climatic and geologic) that are strongly intercorrelated in the study area, with a clear spatial component.
3. The attributes of species from frequently disturbed systems (small size, multivoltinism, diapause, ovoviviparity, etc.) were associated with semi-arid areas whereas traits common in more stable and favourable environments (large body size, semi-voltinism, isolated eggs, etc.) were found in upland forested areas.
4. The natural climatic variation was proposed as a disturbance axis of a theoretical habitat templet (driven by the intense hydrological disturbances typical of semi-arid streams), while anthropogenic pressure (mainly intensive agriculture) and high salinity, a natural consequence of geology, was proposed as an adversity axis. Different life-histories associated with contrasting environmental features were superimposed in this habitat templet.
5. The ecological–evolutionary scenario in which stream macroinvertebrates have evolved and by which their communities are organized, is closely linked to disturbance, environmental harshness and human pressure.     

Biological traits and living conditions of Maya Indian and non Maya girls from Merida,Mexico

A total of 522 girls and their families from low and middle social strate were examined in the northern part of Merida (Yucatan) during 1988 and 1989. Marital radius in the parental generation was relatively long (146 km), and it was six times longer for non-Maya and mixed couples than Maya. Living and housing conditions were similar for both Maya and non-Maya (mixed couples typically had an intermediate condition), except for sewage system (sanitation). The Maya income was 64% lower. Maya men and women were short. The girls from Merida were short, hyper-brachycephalic (short headed), and europrosopic (broad face). Among them, Maya girls were even shorter, more round-headed, and more broad-faced than non-Maya girls. Menarche occurred on the average at an age of 12.6 years in mothers and 12.1 years in daughters. As the generation time was about 25 years, there was a slow acceleration of maturation (0.2 years per decade). Presumably, also stature has increased in recent years.     

Vaterite Otoliths from the Opah,Lampris immaculatus,and Two Species of Sunfish,Mola mola and M. ramsayi

The cosmopolitan opah Lampris immaculatus (also known as the moonfish or mariposa) occurs commonly in New Zealand waters. The otoliths of 23 individuals were examined by light microscopy. All three of the otoliths of the endolymphatic sac of the opah have the characteristic appearance of the Stolkowski crystal form of the vaterite morph of calcium carbonate. Five randomly chosen pairs of asterici and sagittae and two lapilli otoliths were shown by X-ray diffraction to be composed of vaterite. In addition to their mineral composition, the sagitta and astericus of the opah present an unusual combination of anatomical features found in both what are generally regarded as primitive and as advanced fish. Vaterite otoliths also occur in the sunfish Mola mola and M. ramsayi, but with a different crystalline habit to that found in the opah, and in a distinctively different anatomical arrangement of the endolymphatic sac. It is argued that, based on their otolith mineralogy and morphology, the opah and the sunfish are each side of one of the biochemical and anatomical boundaries involved in the separation of the teleosts from other actinopterygian fish (sturgeons, paddle fish, gars and bowfins).     

New records of Acari from the sub-Antarctic Prince Edward Islands

Sixty species of Acari are recorded from the sub-Antarctic Marion and Prince Edward Islands (the Prince Edward archipelago). Twenty of the 45 species collected on recent expeditions are new and currently undescribed. Other new taxa include a family of Mesostigmata, four new genera, and the first sub-Antarctic records of Cillibidae (Mesostigmata) and Eryngiopus (Prostigmata). Fifteen of the 31 species previously reported from the islands are confirmed, although eight of the previous accounts remain doubtful. The fauna, which shows a distinction between the shoreline and terrestrial components, comprises endemic, South Indian Ocean Province and sub-Antarctic mite species. Accepted: 18 July 1998     

Feeding ecology of two nototheniid fishes,Trematomus hansoni and Trematomus loennbergii,from Terra Nova Bay,Ross Sea

 A study of feeding ecology in Trematomus hansoni Boulenger 1902 and Trematomus loennbergii Regan 1913 was carried out from samples collected in the austral summer 1990–1991 off Terra Nova Bay, Ross Sea. T. hansoni was caught between 35 and 566 m and T loennbergii between 311 and 543 m. Stomach contents analysis shows that T. loennbergii relies on a wider range of prey than T. hansoni. Fish and decapods are the main food resources of T. loennbergii, which feeds also on epifaunal and tube-dwelling polychaetes. T. hansoni mostly relies on fish resources that are made up of juvenile stages of fish and eggs. Despite the common area occupied by the two species, the interspecific competition is mostly mitigated due either to taking different prey or to taking different amounts of the same prey. Received: 31 October 1995/Accepted: 20 February 1996     

Plant dispersal in the sub-Antarctic inferred from anisotropic genetic structure

Climatic conditions and landscape features often strongly affect species' local distribution patterns, dispersal, reproduction and survival and may therefore have considerable impacts on species' fine-scale spatial genetic structure (SGS). In this study, we demonstrate the efficacy of combining fine-scale SGS analyses with isotropic and anisotropic spatial autocorrelation techniques to infer the impact of wind patterns on plant dispersal processes. We genotyped 1304 Azorella selago (Apiaceae) specimens, a wind-pollinated and wind-dispersed plant, from four populations distributed across sub-Antarctic Marion Island. SGS was variable with Sp values ranging from 0.001 to 0.014, suggesting notable variability in dispersal distance and wind velocities between sites. Nonetheless, the data supported previous hypotheses of a strong NW-SE gradient in wind strength across the island. Anisotropic autocorrelation analyses further suggested that dispersal is strongly directional, but varying between sites depending on the local prevailing winds. Despite the high frequency of gale-force winds on Marion Island, gene dispersal distance estimates (σ) were surprisingly low (<10 m), most probably because of a low pollen dispersal efficiency. An SGS approach in association with isotropic and anisotropic analyses provides a powerful means to assess the relative influence of abiotic factors on dispersal and allow inferences that would not be possible without this combined approach.