Tropical forest history of the Ecuadorian Andes over the last 34,000 years: preliminary results from pollen and oxygen isotope analyses of Trident 163-13 from the eastern equatorial Pacific [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Pollen from the upper 2.75 m of a core taken 200 km west of the Golfo de Guayaquil, Ecuador (Trident 163-13, 3° S, 84° W, 3,000 m water depth) documents changes in Andean vegetation and climate of the Cordillera Occidental for ~17,000 years before and after the last glacial maximum.

Reducing sea turtle bycatch in trawl nets: a history of NMFS turtle excluder device (TED) research

Thirty-six years ago, NOAA’s National Marine Fisheries Service began research on how to reduce mortality of sea turtles, Chelonioidea, in shrimp trawls. As a result of efforts of NMFS and many stakeholders, including domestic and foreign fishermen, environmentalists, Sea Grant agents, and government agencies, many trawl fisheries around the world use a version of the turtle excluder device (TED). This article chronicles the contributions of NMFS to this effort, much of which occurred at the NMFS Mississippi Laboratories in Pascagoula. Specifically, it summarizes the impetus for and results of major developments and little known events in the TED research and discusses how these influenced the course of subsequent research.

Life history of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) (Richardson, 1836) off the southeastern United States

The life history of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) was described from 1093 specimens collected from Virginia to northern Florida between April 1997 and March 1999. Longitudinally sectioned vertebral centra were used to age each specimen, and the periodicity of circuli deposition was verified through marginal increment analysis and focus-to-increment frequency distributions. Rhizoprionodon terraenovae reached a maximum size of 828 mm precaudal length (PCL) and a maximum age of 11+ years. Mean back-calculated lengths-at-age ranged from 445 mm PCL at age one to 785 mm PCL at age ten for females, and 448 mm PCL at age one to 747 mm PCL at age nine for males. Observed lengthat-age data (estimated to 0.1 year) yielded the following von Bertalanffy parameters estimates: L∞= 749 mm PCL (SE=4.60), K = 0.49 (SE=0.020), and t0= –0.94 (SE=0.046) for females; and L∞= 745 mm PCL (SE = 5.93), K = 0.50 (SE=0.024), and t0= –0.91 (SE = 0.052) for males. Sexual maturity was reached at age three and 611 mm PCL for females, and age three and 615 mm PCL for males. Rhizoprionodon terraenovae reproduced annually and had a gestation period of approximately 11 months. Litter size ranged from one to eight (mean=3.85) embyros, and increased with female PCL.

The early life history of swordfish (Xiphias gladius) in the western North Atlantic

Lengths and ages of sword-fish (Xiphias gladius) estimated from increments on otoliths of larvae collected in the Caribbean Sea, Florida Straits, and off the southeastern United States, indicated two growth phases. Larvae complete yolk and oil globule absorption 5 to 6 days after hatching (DAH). Larvae <13 mm preserved standard length (PSL) grow slowly (~0.3 mm/d); larvae from 13 to 115 mm PSL grow rapidly (~6 mm/d). The acceleration in growth rate at 13 days follows an abrupt (within 3 days) change in diet, and in jaw and alimentary canal structure. The diet of swordfish larvae is limited. Larvae <8 mm PSL from the Caribbean, Gulf of Mexico, and off the southeastern United States eat exclusively copepods, primarily of one genus, Corycaeus. Larvae 9 to 11 mm eat copepods and chaetognaths; larvae >11 mm eat exclusively neustonic fish larvae. This diet indicates that young larvae <11 mm occupy the near-surface pelagia, whereas, older and longer larvae are neustonic. Spawning dates for larvae collected in various regions of the western North Atlantic, along with the abundance and spatial distribution of the youngest larvae, indicate that spawning peaks in three seasons and in five regions. Swordfish spawn in the Caribbean Sea, or possibly to the east, in winter, and in the western Gulf of Mexico in spring. Elsewhere swordfish spawn year-round, but spawning peaks in the spring in the north-central Gulf of Mexico, in the summer off southern Florida, and in the spring and early summer off the southeastern United States. The western Gulf Stream frontal zone is the focus of spawning off the southeastern coast of the United States, whereas spawning in the Gulf of Mexico seems to be focused in the vicinity of the Gulf Loop Current. Larvae may use the Gulf of Mexico and the outer continental shelf off the east coast of the United States as nursery areas. Some larvae may be transported northward, but trans-Atlantic transport of larvae is unlikely.

Life history of South African snoek, Thyrsites atun (Pisces: Gempylidae): a pelagic predator of the Benguela ecosystem

Snoek (Thyrsites atun) is a valuable commercial species and an important predator of small pelagic fishes in the Benguela ecosystem. The South African population attains 50% sexual maturity at a fork length of ca.73.0 cm (3 years). Spawning occurs offshore during winter−spring, along the shelf break (150–400 m) of the western Agulhas Bank and the South African west coast. Prevailing currents transport eggs and larvae to a primary nursery ground north of Cape Columbine and to a secondary nursery area to the east of Danger Point; both shallower than 150 m. Juveniles remain on the nursery grounds until maturity, growing to between 33 and 44 cm in the first year (3.25 cm/month). Onshore– offshore distribution (between 5- and 150-m isobaths) of juveniles is deter-mined largely by prey availability and includes a seasonal inshore migration in autumn in response to clupeoid recruitment. Adults are found through-out the distribution range of the species, and although they move offshore to spawn—there is some southward dispersion as the spawning season progresses—longshore movement is apparently random and without a seasonal basis. Relative condition of both sexes declined dramatically with the onset of spawning. Mesenteric fat loss was, however, higher in females, despite a greater rate of prey consumption. Spatial differences in sex ratios and indices of prey consumption suggest that females on the west coast move inshore to feed between spawning events, but that those found farther south along the western Agulhas Bank remain on the spawning ground throughout the spawning season. This regional difference in female behavior is attributed to higher offshore abundance of clupeid prey on the western Agulhas Bank, as determined from both diet and rates of prey consumption.

Interactions between climatic variables controlling subalpine tree growth: implications for climatic history of the Sierra Nevada, California

EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring records from foxtail pine (Pinus balfouriana) and western juniper (Juniperus occidentalis) growing near tree line in the eastern Sierra Nevada, California, show strong correlations with summer temperature and winter precipitation. Response surfaces portraying tree growth as a function of summer temperature and winter precipitation indicate a strong interaction between these variables in controlling growth. ... Above average growth for both foxtail pine and western juniper from AD 1480 to 1570 can be interpreted as indicating an extended period of warm, moist conditions unequalled during the 20th century.

Holocene history of the El Niño phenomenon as recorded in flood sediments of northern coastal Peru

EXTRACT (SEE PDF FOR FULL ABSTRACT): The Holocene history of flooding in northern coastal Peru is believed to be a proxy record for the El Niño phenomenon. A recently completed set of 30 radiocarbon dates on overbank flood deposits and a tsunami deposit from the Casma region (Figure 1 and Table 1) establishes a chronology for the largest events that have occurred during the last 3500 years. ... The data presented here indicate that events much larger than the one in 1982-1983 may occur with a frequency of about once every 1000 years.

Life history of prawns: a review of recent studies with special reference to Indian species

The paper contains a brief review of the studies on the life histories of Indian species of prawns chiefly belonging to the family Penaeidae. References to similar work carried out outside India are furnished where significant variations have been observed. The three main larval stages viz., Nauplius, Protozoea and Zoea (Mysis) and their important characteristics, including modes of locomotion, are described. The post-larval development of one species that has been studied in detail (Metapenaeus dobsoni) is indicated in outline. Some aspects of the bionomics of these prawns, especially breeding and migration, are also briefly dealt with in view of their relevance in their life cycle. An outline of the life histories of some Palaemonid prawns of both fresh water and marine habitats is added at the end and the need for well- planned investigations in regard to species of such economic value as Palaemon carcinus (Macrobrachium rosenbergii) is indicated.

Ecology and life history of penaeid shrimps

Fourteen species of penaeid shrimps with commercial value in Batan Bay and Tigbauan-Guimbal waters were identified as follows: Penaeus monodon, P.semisulcatus, P.japonicus, Metapenaeus ensis, M.burkenroadi, M.endeavouri, Metapenaeopsis palmensis, M.stridulans, Trachypenaeus fulvus, and Parapenaeus longipes. Among the 14 penaeids, P.semisulcatus, M.ensis and M.palmensis were found to be the dominant species within each genus. There are seven existing fishing gears for shrimping in the Batan Bay and Tigbauan-Guimbal waters: fish corrals, lift net, filter net, gill net, skimming net, baby trawler and commercial trawler. In general, female penaeids are larger than males. The largest P.monodon female measured was 81 mm in carapace length with 23 g in body weight. The largest male measuring 59 mm in carapace length with 119 g of body weight was caught in Batan Bay. Judging from spermatozoa occurrence on both sexes of P.monodon, the biological minimum size for male is 37 mm in carapace length and 49 mm for female. A total of 133 Penaeus postlarvae obtained from the offshore were identified by comparison with those reared in the laboratory. The postlarvae of P.japonicus-latisulcatus complex were quite dominant (60 . 2%), followed by P.semisulcatus (18 . 0%), and P.merguiensis-indicus complex (17 . 3%). The number of P.monodon postlarvae was relatively small (4 . 5%). The modal carapace length of P.monodon postlarvae from the offshore was 1 . 3 mm with three or four dorsal and no ventral spines on the rostrum, while P.monodon fry from the shoreline had 2 . 3 mm with five or six dorsal and one or two ventral spines.

Developmental and ecological stages in the life history of milkfish Chanos chanos Forsskal

Seven stages in the life history of the milkfish C. chanos , are recognized and suggested: A, embryonic; B, yolksac larval; C, larval; D, postlarval; E, juvenile; F, subadult; G. adult. An outline is presented of the life history. It is concluded that the milkfish, throughout the known stages of their life history are well adapted and equipped for optimal survival. High swimming performance, broad flexibility in feeding habits, high adaptability to a wide range of physicochemical conditions of the environment are but a few of the adaptations. The main driving force in all developmental stages is the evolutionary response to food distribution and availability followed by predation pressure.

The natural life history of milkfish

Following brief descriptions of the various phases in the natural life history of the milkfish (Chanos chanos), namely adults, eggs and embryos, larvae, fry and metamorphosis, juveniles and sub-adults, a summary is provided of the life history, providing also a schematic diagram.

The history of fish communities, biodiversity and environment of Lake Victoria and the lessons learnt

The first fishery survey of Lake Victoria was conducted between 1927 and 1928 (Graham 1929). Atthat time, the lake had a diverse fish fauna and the fishery was dominated by two endemic tilapiine cichlids; Oreochromis esculentus (Graham 1929) and O. variabilis (Boulenger 1906). There were a number of other species such as Protopterus aethiopicus Heckel 1851, Bagrus docmac (Forsk.) 1775, Clarias gariepinus (Burchell), Barbus species, mormyrids, Synodontis spp, Schilbe intermedius (Linn.) 1762 and Rastrineobola argentea Pellegrin, 1904 that were also abundant in the lake most of which made a significant contribution to the fishery (Graham 1929, Worthington 1929, 1932, Kudhongania & Cordone 1974). Haplochromine cichlids were represented by at least 300 species more than 99% of them endemic (Greenwood, 1974; Witte et al., 1992 a & b). The fishery of Lake Victoria was similar to that of lakes Kyoga and Nabugabo (Worthington 1929; Trewavas 1933; Greenwood 1965, 1966; Beadle 1962, 1981). There were also important fisheries on the inflowing rivers of Lake Victoria, the most important of which were Labeo victorianus and Barbus altianalis (Cadwallader 1965). The small sized species notably Rastrineobola argentea and haplochromines cichlids were not originally commercially exploited.