Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands,southern Indian Ocean

During three summer surveys at Prince Edward Island (PEI), southern Indian Ocean (2001, 2004 and 2008), 416 southern elephant seals Mirounga leonina were inspected for identification tags. In all, 42 seals that had been tagged as weaned pups at their natal site were found on Marion Island (MI), 38 of which could be individually identified by resighting their tag numbers. The majority of the MI-tagged seals were yearlings or subadults, and all but one were hauled out at PEI for the annual moult. The attendance rate of the known individuals at their natal island during the annual moult was only 40%, based on their resighting histories. This was significantly lower than the 77 ± 6% moult attendance rate estimated for a random MI population sample drawn from the same cohorts (based on 10 000 replications). Annual resight probabilities (considering all haulout phases) was 58% per annum for the MI seals seen at PEI, and 80 ± 4% for the simulation. Seasonal and annual absences of seals from MI violate the ‘homogeneity of capture’ assumption of mark-recapture models. When multiple sightings during any year are treated as a single sighting, resights during other haulouts (e.g. breeding) compensate only partially for absences during the moult. Therefore, mark-recapture studies undertaken in archipelagos should ideally include both marking and resighting of individuals on all islands which will allow discrimination between mortality and local migration.     

Foraging habitats of southern elephant seals,Mirounga leonina,from the Northern Antarctic Peninsula

Elephant Island (EI) is uniquely placed to provide southern elephant seals (SES) breeding there with potential access to foraging grounds in the Weddell Sea, the frontal zones of the South Atlantic Ocean, the Patagonian shelf and the Western Antarctic Peninsula (WAP). Quantifying where seals from EI forage therefore provides insights into the types of important habitats available, and which are of particular importance to elephant seals. Twenty nine SES (5 sub-adult males—SAM and 24 adult females—AF) were equipped with SMRU CTD-SLDRs during the post-breeding (PB 2008, 2009) and post-moulting (PM 2007, 2008, 2009, 2010) trips to sea. There were striking intra-annual and inter-sex differences in foraging areas, with most of the PB females remaining within 150 km of EI. One PB AF travelled down the WAP as did 16 out of the 20 PM females and foraged near the winter ice-edge. Most PM sub-adult males remained close to EI, in areas similar to those used by adult females several months earlier, although one SAM spent the early part of the winter foraging on the Patagonian Shelf. The waters of the Northern Antarctic Peninsula (NAP) contain abundant resources to support the majority of the Islands' SES for the summer and early winter, such that the animals from this population have shorter migrations than those from most other populations. Sub-adult males and PB females are certainly taking advantage of these resources. However, PM females did not remain there over the winter months, instead they used the same waters at the ice-edge in the southern WAP that females from both King George Island and South Georgia used. Females made more benthic dives than sub-adult males—again this contrasts with other sites where SAMs do more benthic diving. Unlike most other populations studied to date EI is a relatively southerly breeding colony located on the Antarctic continental shelf. EI seals are using shelf habitats more than other SES populations but some individuals still employ open water foraging strategies. Sea-ice was also very influential for PM females with more foraging occurring in heavier pack-ice. Larger females used areas with heavier ice-concentration than smaller females. The study demonstrates the importance of shelf and slope habitat to elephant seals, but also highlighted the influence of sea-ice and fine-scale bathymetry and local ocean condition in determining foraging habitat.     

New records of southern elephant seals Mirounga leonina L. on the coast of southern Africa

Systematic recording of elephant-seal sightings, including 92 hitherto unpublished records, has increased the number of records on the coast of southern Africa to 130. The data set is now the largest on record for any southern continent other than Antarctica. It provides an opportunity to examine the biological significance of such matters as seasonality, possible causes of haul-out, their possible origins and implications for interpretation of elephant-seal dispersal around their breeding colonies. The number of sightings has increased recently. The overall sex ratio is 52,4 per cent male to 21 per cent female, 26,6 per cent being of indeterminate sex. The seals haul out mainly from November to February, and indications are that males and females disperse straight after the breeding season and a few months later reach the coast of southern Africa. The most likely primary cause of haul-out for immature seals is to moult. It is postulated that the seals originated mainly from South Georgia. It is not clear if the seals recorded are true vagrants or the outer fringe of a normal dispersal. Of the sightings, 24 were tagged after arrival, and of these, 13 were sighted more than once and 6 showed a regular pattern of movement. There were 19 sightings of elephant seals at local fur-seal rookeries and, with one exception, the two species co-existed peacefully. There are three confirmed and two unconfirmed births on the coast. The ability to develop a preference for unfamiliar places and to pup outside their natal colonies could explain how they colonize new areas.     

Southern elephant seal trajectories, fronts and eddies in the Brazil/Malvinas Confluence

This study describes the association between transient, mesoscale hydrographic features along the axis of the Brazil–Malvinas Confluence, in the SW Atlantic, and the foraging behavior of 2–3-year-old (focal) juvenile southern elephant seals, Mirounga leonina, from Península Valdés, Argentina. Departing from the dominant pattern of foraging on predictable bathymetric fronts on the Patagonian shelf and slope, three females out of 12 satellite-tracked juveniles remained at the edge of young warm-core eddies and near the outer core of cold-core eddies, coinciding with the most productive areas of these temperature fronts. Seal trajectories along high-temperature gradients were always consistent with the speed and direction of surface currents inferred from the temperature distribution and confirmed by surface drifters. Movements of foraging seals were compared with those of surface drifters, coinciding in time and space and yielding independent and consistent data on regional water circulation parameters. The diving pattern recorded for one focal seal yielded shallower dives and a loose diel pattern in the eddy, and a marked diurnal cycle compatible with foraging on vertically migrating prey in the cold waters of the Malvinas Current. Pre-reproductive females that use the mesoscale fronts of the Argentine Basin as an alternative foraging area would benefit from lower competition with more experienced seals and with other top predators that reproduce along the coast of Patagonia.     

Population dynamics of southern elephant seals: a synthesis of three decades of demographic research at Marion Island

Southern elephant seal Mirounga leonina numbers declined precipitously throughout most of their circumpolar distribution since the 1950s. A long-term intensive demographic programme was initiated in 1983 on the relatively small population of southern elephant seals at sub-Antarctic Marion Island in an attempt to identify causative mechanisms associated with this decline. Weaned pups have been tagged annually since 1983, and this has produced a large number of individuals of known identity. A regular resighting programme yielded a mark-recapture dataset that has been subjected to numerous survival-based models. This ongoing programme produced a substantial body of scientific literature on population growth patterns, vital rates (survival and fecundity) and population regulation in southern elephant seals, which are reviewed in this synthesis. We briefly describe the analytical framework common to much of the demographic research, highlight important conclusions concerning population regulation of elephant seals at Marion Island, and discuss priorities for future research.     

Further birth records of elephant seals Mirounga leonina in New Zealand (note)

The second and third recorded births of southern elephant seals Mirounga leonina on the mainland of New Zealand occurred at Kaikoura in mid‐October 1976. One female pup died within 14 d of birth and the other (sex unknown) disappeared from the region with its mother on 19 November 1976.     

Deep divers in shallow seas: Southern elephant seals on the Patagonian shelf

Elephant seals are wide-ranging, pelagic, deep-diving (average of 400–600 m) predators that typically travel to open waters and continental shelf edges thousands of kilometers from their land breeding colonies. We report a less common pattern of foraging in the shallow waters of a continental shelf. Southern elephant seals, Mirounga leonina, that breed at Península Valdés (Argentina), face an extended (∼1,000,000 km²; 400–700 km-wide, depending on track), shallow (<150 m) and seasonally productive plateau, the Patagonian shelf. Adults of both sexes usually cross it in rapid transit to other potential foraging grounds on the shelf edge or in the Argentine Basin, but 2–4 year-old juveniles spread over the plateau and spent months in shallow waters. This behavior was recorded for 9 seals (5 males and 4 females) of 23 satellite-tracked juveniles (springs of 2004 and 2005) and for 2 subadult males studied in previous seasons. Trips included travel trajectories and time spent in areas where swim speed decreased, suggesting foraging. Preferred locations of juvenile females were in the proximity of the shelf break, where stratified waters had relatively high phytoplankton concentrations, but young and subadult males used the relatively cold (7–8 °C), low-salinity (∼33.3) mid-shelf waters, with depths of 105–120 m and a poorly stratified water column. Three of the latter seals, instrumented with time–depth recorders, showed dives compatible with benthic feeding and no diel pattern of depths distribution. Regions of the mid-shelf were used in different seasons and were associated with low chlorophyll-a concentration at the time of the visit, suggesting that surface productivity does not overlap with putative quality habitat for benthic foragers. Benthic diving on the shallow mid-shelf would be a resource partitioning strategy advantageous for young males prior to greater energetic demands of a high growth rate and a large body size. Later in life, the more predictable, bathymetry-forced, shelf-break front may offer the food resources that explain the uninterrupted increase of this population over several decades.     

Review of the current distribution of southern elephant seals in the eastern South Pacific

The eastern South Pacific southern elephant seal population was extinguished by extensive hunting and the current presence of this species in this area is not well understood. We reviewed existing records from the 1900s to 2014 in the eastern South Pacific, as well as tagged seals and movement records in order to assess the potential immigration source of these individuals. A total of 409 confirmed sightings were compiled, ranging from the southern tip of South America (Cape Horn Archipelago) as far north as Ecuador, including some oceanic island groups. The evidence shows also that recolonisation of its former Pacific distribution has started, with slow population growth in three incipient pupping sites in southern Chile (south of 51°S). Although the source of all of the individuals in the growing colonies is unknown, evidence from tags and satellite tagging indicates that some seals come from subpopulations on the Peninsula Valdes and the Falkland/Malvinas Islands, although mtDNA analysis showed, preliminarily, a greater genetic relationship only with the Falkland/Malvinas Islands rookery.     

Distribution,behaviour and photo-identification of Atlantic humpback dolphins Sousa teuszii off Flamingos,Angola

Atlantic humpback dolphins Sousa teuszii are a priority for research due to their restricted geographic range, narrow ecological niche and the paucity of existing information. The distribution and behaviour of S. teuszii off Flamingos, southern Angola, was investigated during summer and winter 2008 using boat- and shore-based surveys. In all, 71 S. teuszii sightings were recorded, ranging from one to eight animals. Sousa teuszii inhabited shallow, nearshore waters throughout the region, with the exception of southern areas adjacent to fishing villages. Small bays, sheltered waters behind reef-breaks and areas off dry river mouths were used for foraging/feeding behaviour, whereas most travelling occurred along exposed coast. Ten individual S. teuszii were photo-identified. Multiple resightings (and absence of unmarked animals) indicate that all individuals present at the time of the surveys were photocaptured, exhibited high site fidelity and had year-round occurrence. Association indices of 0.77-1.0 indicated strong social affiliation between eight individuals, particularly in winter. Off Flamingos, S. teuszii occurs in small numbers and exhibits high site fidelity to a relatively small stretch of nearshore habitat, making the species vulnerable to local extirpation. Wider-scale surveys and development of a management plan are crucial to ensuring the long-term conservation of S. teuszii off Flamingos.     

Assessing the competitive effects of marine mammal predation on commercial fisheries

Commercial fishermen in many parts of the world perceive marine mammals as competitors for a scarce resource: fish. The importance of predation by marine mammals can be evaluated crudely by considering the marine mammal as a rival fishery whose operation is constrained by physiology and energetic requirements, rather than by catch limits and gear restrictions. Evidence collected from grey seals Halichoerus grypus in the United Kingdom, southern elephant seals Mirounga leonina and beluga whales Delphinapterus leucas shows that published information on distribution, based on the location of breeding sites and sightings in shallow water, may give an unrealistic picture of foraging distribution. Studies of diet and distribution can give an impression of the static nature of the inter-action between a marine mammal and the fishery. However, it is the dynamics of the interaction which are important. A critical question to be posed is how will the consumption of a particular prey species vary with its availability to the predator?     

南极乔治王岛象海豹数量的初步估计

本文通过对南极乔治王岛象海豹数量的观察,初步估计了该处的种群数量;期望能为南极象海豹资源的开发和利用提供依据。     

Seasonal anecdysis and moulting synchrony in field populations of Palaemon elegans (Rathke)

A population of Palaemon elegans studied during 1978–1980 showed a characteristic moult cycle structure according to season, comprising a winter anecdysis, ‘epidemic’ spring moulting and synchrony of moult cycle development. The initiation of moulting in the spring was temperature-dependent, an estimated environmental temperature of 7–8 °C being necessary to allow moulting. Developmental synchrony during the moult cycle was observed following the initial spring moults, and it is thought that the degree and duration of moult synchrony is temperature-dependent. Synchrony is lost during the summer. Despite seasonal climatic differences between years, little difference in the time of appearance of berried females was seen. It is thought that oogenesis is controlled primarily by photoperiodic rather than temperature-dependent mechanisms. During egg development the moult cycle of ovigerous females was prolonged during intermoult stages and, during late vitellogenesis, premoult stages were prolonged.     

The effects of seal-swim activities on the New Zealand fur seal (Arctophoca australis forsteri) in the Bay of Plenty,New Zealand,and recommendations for a sustainable tourism industry

Wildlife tourism (including pinniped tourism) offers people the opportunity to see wildlife in their natural environment. It can provide positive outcomes for the animals, through improved resources for conservation, or negative outcomes, such as inducing the animals to move away. This study assessed the impacts and sustainability of a novel but growing tourism industry, swimming with seals, based on interactions with New Zealand fur seals (Arctophoca australis forsteri) in the Bay of Plenty, New Zealand, between December 2011 and March 2012. The behaviour of all seals in the water (interaction, neutral, and avoidance) was monitored at 1 min intervals, during 16 seal-swim events. Seals mostly ignored the swimmers (54% of records), some interacted with swimmers (41%); seals rarely avoided the swimmers (5%). Interactions peaked in frequency at 6 min into the swims, then declined. They occurred most frequently during December, corresponding with the pupping period when juvenile seals—the age class most likely to interact—are excluded from breeding areas and so spend much of their time in the water. Compliance of tour operators to regulations was also monitored during seal-swim activities and the industry was found to be highly compliant. The results suggest the activities monitored had minimal impact on seals in the water, and are likely to be sustainable in relation to seal conservation. Tourism can be site and time specific, and it is recommended that approaches such as those trialled here be adopted to monitor other wildlife tourism activities to ensure their sustainability. Further research needs to examine potential impacts of the tours on seals ashore.     

Growth rate in a population of the freshwater crayfish,Paranephrops planifrons white

Observations on growth increments at moult in a population of freshwater crayfish, Paranephrops planifrons, were made from periodic recaptures of marked animals. The growth increment increased with increasing size of crayfish up to about 20 mm carapace length (65 mm total length) after which a slight decrease was evident. By analysis of the size distributions in samples taken at different times of year it was found that four to five year classes were normally present. Growth of these age components could be followed through consecutive samples. Mean size at leaving the parent in December was 3.5 mm, after one year 11.4–11.8 mm, after two years 18.2–19.3 mm, after three years 22.1–23.8 mm, and after four years 26.7–29.6 mm, all sizes quoted as carapace lengths. After sexual maturity growth in the females was less than in the males. The number of moults completed by each year class was found by relating data on growth increment per moult to growth shown in consecutive quantitative samples. In the first year of life nine moults were completed, in the second year three moults, in the third year two moults, and in the fourth one moult. Independent data on moult frequency recorded from marked crayfish agreed well with these figures.     

3.7 Ma以来西菲律宾海XT-4孔沉积物元素特征及其古环境指示意义

对西菲律宾海盆南部XT-4孔柱状沉积物进行了元素地球化学分析,利用常量元素上地壳标准化图解和R型因子分析方法进行了物源探究,利用因子分析得出的陆源因子得分变化探讨了物源区的古环境演化。结果表明：XT-4常微量元素垂向上变化主要受控于亚洲内陆的风尘物质和周边火山物质的输入,海洋自生物质也有一定的贡献。以TiO₂和K₂O等元素为代表的陆源因子得分自3.7 Ma BP以来表现出阶段性上升的变化趋势,与中国黄土和北太平洋ODP 885/886站沉积物记录的东亚冬季风演化记录有着良好的对比性,同时与青藏高原主要的阶段性隆升时间相对应,响应了晚新生代以来青藏高原隆升对东亚冬季风加强的作用。本研究丰富了西菲律宾海盆的风尘沉积研究,为后续研究提供一定的认识基础。     

Size‐based differences in isotopic niche width (δ13C and δ15N) of green turtles (Chelonia mydas) nesting on Príncipe Island,Gulf of Guinea

Within the same population, nesting green turtles (Chelonia mydas) might exploit different niches by exhibiting polymorphic foraging strategies and/or inhabiting geographically distinct foraging areas. This is crucial information for the conservation of this species. Here, we used stable carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) to test for differences in a population of green turtles nesting on Príncipe Island (1°37′N; 7°24?′E), Central Africa. A total of 60 nesting females were sampled on the two main nesting beaches of the island in December 2012. Minimum curved carapace length (CCL) was recorded, and δ¹³C and δ¹⁵N values were measured in the epidermis of each individual. Overall, CCL varied from 87.0 to 108.0 cm (mean ± SD =100.0 ± 5.1), δ¹³C values from ?19.4 to ?8.6‰ (?17.3 ± 1.8) and δ¹⁵N values from 7.9 to 17.3‰ (13.6 ± 1.5). Despite the large variation in both isotopic ratios, their distributions were unimodal, showing an absence of polymorphic foraging strategies and isotopically distinct foraging areas. However, smaller females (< median, 100.8 cm) occupied a much larger isotopic niche (i.e., four times greater) than larger females. These results suggest that nesting green turtles may forage opportunistically on the resources available in each of their foraging home ranges, with smaller females venturing to more isotopic‐diversified areas and/or exhibiting broader foraging strategies than larger females. In addition, and in accordance with other studies, findings suggest that the foraging grounds used by the Príncipe green turtle nesting females are distributed mainly throughout the Gulf of Guinea.     

Reproductive cues in Panulirus ornatus

Two experiments were performed to assess the effect of photoperiod and temperature on spawning of Panulirus ornatus. In experiment 1, sexually mature lobsters taken from the wild during summer were held at one of two photoperiods, winter (13 Light: 11 Dark) and summer (14.5 Light:9.5 Dark). Additionally, lobsters were also exposed to either summer (29°C) or winter (24°C) average water temperatures. Spawning was significantly greater when animals were exposed to summer photoperiod than to winter photoperiod, irrespective of temperature. Although a higher percentage of lobsters spawned when placed under a higher temperature, this trend was not statistically significant. In experiment 2, sexually mature lobsters were taken from the wild during winter and exposed to the same two photoperiods as in experiment 1, at a summer equivalent temperature of 29°C. Breeding started earlier and was more successful at the summer photoperiod. Time to first breeding was 17 weeks after exposure to summer photoperiod, compared with less than 1 week in experiment 1, and did not occur until individuals had moulted. Moulting occurred in 81% of lobsters, primarily after an increase in temperature to 29°C. The time between moulting and mating was varied and there was no significant difference in moult frequency between the two experimental photoperiods. After the lobsters had moulted, breeding success was reached earlier if photoperiod was lengthened. Results suggest photoperiod is the primary cue for the onset of gonad maturity and mating activity, with temperature playing a less important role. Physiological rest and possibly a moult may be required between breeding seasons before spawning can occur. Furthermore, temperature may be an important cue for pre‐reproduction moulting.     

Structure of Haida Eddies and Their Transport of Nutrient from Coastal Margins into the NE Pacific Ocean

Anticyclonic mesoscale eddies form near shore each winter in the Gulf of Alaska. One site near the Queen Charlotte Islands is shown to produce eddies that transport from 3000 to 6000 km³ of coastal water up to 1000 km westward. Eddies carry shelf nutrients either into the high nutrient, low chlorophyll waters of the NE Pacific, or in a more southerly direction into seasonally nitrate depleted waters. A large eddy sampled in summer 1998 was found to have elevated particulate levels on its perimeter. Nitrate supplied to the euphotic zone by this eddy during its natal summer is estimated to be three times greater than the usual seasonal nutrient transport in the Gulf of Alaska. This revised version was published online in August 2006 with corrections to the Cover Date.     

Species composition,abundance and biomass of microphytoplankton in the KwaZulu-Natal Bight on the east coast of South Africa

Nearshore marine environments are influenced by an array of variables that can either be land-derived or of marine origin, and nearshore phytoplankton communities may differ in their taxonomic composition and biomass in response to such variables. The KwaZulu-Natal Bight (hereafter referred to as ‘the bight’) is an oligo-mesotrophic, nearshore oceanic environment, that is influenced by both terrestrial run-off and upwelling. A microphytoplankton survey of the bight conducted over several stations and depths and two seasons was conducted in order to ascertain species composition, abundance and biomass. Microphytoplankton abundance was generally low (a maximum of 180 000 cells l–1 was recorded) but differed considerably between sites and seasons. A total of 99 taxa of mainly Bacillariophyceae and some Dinophyceae, Prymnesiophyceae and Cyanophyceae were identified in the present study. In the central bight, higher abundance and biomass were measured in February (wet season), which may be a possible consequence of terrestrial nutrient inputs. In the northern and southern bight we measured higher abundance and biomass in August (dry season). Upwelling was not detected during the study, but an influence of terrestrial nutrient sources was detected at the coastal stations. Turbid conditions were specific to the site near the Thukela River mouth and possibly influenced abundance, biomass and species composition at this site. Historic data on microphytoplankton composition are scarce, but comparisons with surveys from the 1960s reveal that around 60% of the common diatoms recorded then also occurred in the present study. Small taxa [20–200 µm] dominated the microphytoplankton community. Community composition was fairly uniform throughout the bight in both seasons, dominated in general by Chaetoceros species, and on occasion co-dominated by Thalassionema nitzschioides and Dactyliosolen fragilissimus.     

Photo-identification and habitat use of Atlantic humpback dolphins Sousa teuszii around the Río Nuñez Estuary in Guinea,West Africa

Ecological data for the Atlantic humpback dolphin Sousa teuszii are scant. Six on-effort Sousa teuszii sightings were recorded during 817.6?km of boat-based effort in the Río Nuñez region of Guinea during October and November 2013. Two incidental sightings were also reported. Groups comprised 1–25 animals. Photo-identification produced a minimum population estimate of 47 animals. Most sightings (n = 5) were located close (<1?km) to shore along a 5.7?km stretch of coast on the west side of Île de Taïdi, primarily over shallow, sand–mud habitat. Two very distinctive individuals were present in all four Taïdi photo-identification encounters, suggesting high site fidelity and stable associations. Two sightings occurred in the outer Río Nuñez Estuary much farther from the coast (5–12?km) but in relatively shallow water (≤15?m) over sand–mud sediment. Focal follows (n = 5: 0.2–3.8?h duration) produced 9.02?h of behavioural data. Travel (51%), foraging (39%) and feeding (9.2%) dominated, with Taïdi dolphins spending more time foraging and feeding than the outer estuary groups. Three individuals had linear-severed dorsal fins consistent with injuries from fishing line. Some management implications of variation in habitat, site fidelity and movements of Sousa teuszii groups are discussed.