Life-history variation in Rhodophysema elegans (Palmariales, Rhodophyta) from the North Atlantic and crustose Rhodophysema spp. from the North Pacific

1989 ◽  
Vol 67 (10) ◽  
pp. 2857-2872 ◽  
Author(s):  
G. W. Saunders ◽  
C. A. Maggs ◽  
J. L. McLachlan
Keyword(s):  
Life History ◽  
North Atlantic ◽  
Life Histories ◽  
North Atlantic Ocean ◽  
Sexual Life ◽  
Type I ◽  
Life History Variation ◽  
The North ◽  
The Pacific ◽  
The North Atlantic

Two life histories have been established for Rhodophysema elegans from the North Atlantic Ocean by field and culture studies. These are entirely distinct and occur, respectively, in (i) sexual, tetrasporangial and (ii) asexual, bisporangial populations. In tetrasporangial isolates, a sexual life history was unequivocally indicated by chromosome numbers of n = 18 in vegetative cells and 18 pairs during meiotic tetrasporocyte division. Bisporangial plants, interpreted as polyploid gametophytes (2x = 36), undergo a direct, mitotic bispore to bisporophyte life history and also produce diploid spermatia. The sexual life history in North Atlantic R. elegans differed in several respects from that reported in a Californian isolate. A taxonomic study of crustose Rhodophysema species from the Pacific Ocean in comparison with type material of R. elegans from France indicated that two entities have been reported from Pacific North America under this name, but neither corresponds with the type. (i) Crusts epiphytic on the seagrass Phyllospadix and algal fronds are identified as Rhodophysema odonthaliae, described from Japan. Evidence of both sexual and direct, mitotic tetrasporangial life histories has been observed in field collections of this species, (ii) Larger plants, with much larger spermatangia, collected on pebbles and brown algal stipes are considered as being growth forms of the monostromatic Californian species Rhodophysema minus.

scholarly journals Otolith chemistry as an indicator of movements of albacore (Thunnus alalunga) in the North Atlantic Ocean

2016 ◽  
Vol 67 (7) ◽  
pp. 1002 ◽  
Author(s):  
Igaratza Fraile ◽  
Haritz Arrizabalaga ◽  
Josu Santiago ◽  
Nicolas Goñi ◽  
Igor Arregi ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Life History ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The North ◽  
Otolith Core ◽  
Thunnus Alalunga ◽  
The North Atlantic ◽  
Migratory Patterns

Albacore (Thunnus alalunga) in the North Atlantic Ocean is currently managed as a single well-mixed stock, although this assumption remains contentious. We measured stable isotopes (δ13C and δ18O) and trace elements (Mg, Mn, Sr, Ba) in otoliths of albacore collected from two feeding grounds, namely the Bay of Biscay and Atlantic offshore waters, and compared them among sampling locations and life history stages. Measurements in otolith core, post-core and edge were used to determine whether albacore from these two regions have the same nursery origin and migratory patterns. We found no clear evidence of distinct nursery grounds based on otolith core chemistry, but Sr:Ca and Mg:Ca were different in the post-core portions of albacore from the two locations, suggesting residency in different regions during the early juvenile stage. Otolith edge chemistry, particularly stable isotopes and Sr:Ca, proved to be a valuable tool for classifying individuals to their capture locations. Annual cycles of Sr:Ca ratios were visible along life history transects, likely reflecting migratory patterns between water masses of differing salinity, but the timing of Sr:Ca cycles differed between the two groups. Differentiation in trace element concentrations in the otolith post-core and the timing of Sr:Ca cycles suggest the occurrence of two migratory contingents of albacore in the north-east Atlantic Ocean.

scholarly journals The North Atlantic Ocean as habitat for Calanus finmarchicus: Environmental factors and life history traits

2014 ◽  
Vol 129 ◽  
pp. 244-284 ◽  
Author(s):  
Webjørn Melle ◽  
Jeffrey Runge ◽  
Erica Head ◽  
Stéphane Plourde ◽  
Claudia Castellani ◽  
...  
Keyword(s):  
Life History ◽  
Environmental Factors ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Life History Traits ◽  
North Atlantic Ocean ◽  
Calanus Finmarchicus ◽  
The North ◽  
The North Atlantic

The Salinity of the North Atlantic Ocean and the Next Glaciation

1972 ◽  
Vol 2 (3) ◽  
pp. 399-400
Author(s):  
Peter K. Weyl
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Surface Salinity ◽  
The North ◽  
Isthmus Of Panama ◽  
The Pacific ◽  
Salinity Reduction ◽  
Caribbean Area ◽  
The Caribbean ◽  
The North Atlantic

A reduction in the surface salinity of the North Atlantic, by causing an extension of sea ice, could initiate the next Glacial period. Such a salinity reduction could be the result of a slight persistent change in surface pressure in the Caribbean area, that reduces the transfer of water vapor from the Atlantic to the Pacific across the Isthmus of Panama.

scholarly journals Was the North Atlantic Ocean well-ventilated during Oceanic Anoxic Event 2 in the mid-Cretaceous?

2013 ◽  
Vol 10 (8) ◽  
pp. 13231-13276
Author(s):  
I. Ruvalcaba-Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
North Atlantic Ocean ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

Palmaria mollis stat. nov.: a newly recognized species of Palmaria (Rhodophyceae) from the northeast Pacific Ocean

1985 ◽  
Vol 63 (3) ◽  
pp. 398-403 ◽  
Author(s):  
John P. van der Meer ◽  
Carolyn J. Bird
Keyword(s):  
Pacific Ocean ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
North Pacific Ocean ◽  
Palmaria Palmata ◽  
Cytological Examination ◽  
The North ◽  
The Pacific ◽  
The North Atlantic

Attempts were made to hybridize Palmaria palmata (L.) O. Kuntze from the North Atlantic Ocean with Palmaria palmata f. mollis (Setchell and Gardner) Guiry from the eastern North Pacific Ocean. No hybrids were obtained in reciprocal crosses, although fertilization was readily achieved for control crosses within each taxon. The number and placement of carpogonia on well-developed female gametophytes (disc diameter, 100–150 μm) was different for the two taxa. The Atlantic plants had comparatively few carpogonia (1–10), which were always found at the center of the holdfast disc or on young upright fronds, whereas the Pacific plants had many carpogonia (15–60), which were most commonly located away from the centermost portion of the disc and were never observed on developing fronds. The two taxa also differed in their susceptibility to a small parasitic Oomycete of the genus Petersenia Sparrow, which is pathogenic for f. mollis but did not infect the Atlantic plants. Cytological examination revealed that f. mollis has n = 21 chromosomes, the same as P. palmata from the north Atlantic Ocean. In view of the genetic isolation between the two forms, P. palmata f. mollis is raised to specific status as Palmaria mollis (Setchell & Gardner) van der Meer & Bird.

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