Macroramphosus

Abstract: Interspecific relationships of 4 dominant fish species of the Great Meteor seamount fish community (subtropical NE Atlantic, 30°N, 28.5°W), Macroramphosus spp. Lacepede 1803, Capros aper (L. 1758), Antigonia capros Lowe 1843 and Zenopsis conchifer (Lowe 1852) were analysed with respect to diet composition, habitat-dependent resource utilisation and niche overlap. For all 4 species, planktonic and micronektonic prey prevailed. In terms of the Relative Importance index (RI), the benthic share was 18.25% RI for Macroramphosus spp., 19% RI for C. aper and 20.38% RI for A. capros. Prey of Z. conchifer consisted of 48.57 % RI mesopelagic and pelagic fishes and of 47.7% RI bentho-pelagic fishes. For all fishes, a permutation test revealed significant selection of prey in plateau margins of the seamount. Unweighted and novel-weighted overlap indices combining prey composition, habitat use and prey utilisation within habitats revealed high overlap between the boarfishes A. capros and C. aper and smaller overlap between other pairs. The results are in support of the sound scattering layer interception hypothesis (Isaacs & Schwartzlose 1965), which implies: (1) primarily pelagic food utilisation for bentho-pelagic fishes; (2) increased habitat-dependent utilisation rates at locations of interception with the sound-scattering layer; (3) diel changes in utilisation rates due to availability of prey; (4) sufficient resource partitioning among species in order to avoid competitive exclusion.

Abstract: Quantitative data collected with different bottom trawls at the Great Meteor Seamount (subtropical NE Atlantic, 30°N; 28.5°W) in 1967, 1970 and 1998 are compared. Bootstrap estimates of total catch per unit effort increased from 6.96 and 10.8 ind. m–1 h–1 in 1967 and 1970, respectively, to 583.98 ind. m–1 h–1 in 1998. Gear effects and an effect of gear over time accounted for 47.1% and 20% of species variability. Further significant factors were time of day and habitat, while season was not significant. A total of 43 species was collected. Including supplementary species information, a grand total of 46 species was found associated with the Great Meteor Seamount. Diversity was higher in 1967 and 1970 (Shannon's diversity: H′=2.5 and 1.6) than in 1998 (H′=0.9). Species–environment relationships are discussed in terms of a sound-scattering layer–interception hypothesis, i.e. utilisation of prey from a diurnally moving sound-scattering layer for the bentho-pelagic community. This is probably augmented by concentration effects in a circular current around the seamount (Taylor-column). Long-term changes are discussed with respect to a decrease in biodiversity due to considerable increases in Macroramphosus scolopax and Capros aper. In 1998, the increase of abundance of Trachurus picturatus and the respective decreases for genuine benthic species were likely to have been caused by a change of gear.

Abstract: We studied the diet of the Common Tern (Sterna hirundo) in several islands of the Azores during 1994, based on the analysis of 777 food pellets. The diet of Common Terns was based on a few species of small pelagic fish. Trumpet Fish (Macroramphosus spp.) dominated the diet in terms of both frequency of occurrence (84%) and numerical frequency (69%). This species, together with Boarfish (Capros aper), Blue Jack Mackerel (Trachurus picturatus) and lantern fish (Families Myctophidae, Sternoptychidae, Diretmidae), accounted for more than 96% of the prey taken by Common Terns on all the islands. Insects occurred in 10% of all pellets analyzed and were present in almost 15% of the pellets from Corvo. Lantern fish represented an important fraction of the diet of Common Terns in the Azores and included several species previously undescribed as prey of seabirds in the region. Comparisons with dietary data obtained in subsequent years showed little inter-annual variability in the frequency of abundance of ...

Abstract: Among over 30 000 species of ray-finned fishes, seahorses and pipefishes have a unique feeding mechanism whereby the elastic recoil of tendons allows them to rotate their long snouts extremely rapi...