Edward M. Hulburt

The effects of enriching Sargasso sea water on the production and species composition of the phytoplankton

Abstract The technique of artificial enrichment of sea water has been used in an attempt to define nutrients critically limiting the growth of phytoplankton in the Sargasso Sea. It is shown that final population growth achieved with different enrichment is a function of time. In 3-day experiments, iron appeared essential while in 7-day experiments nitrogen and phosphorus alone produced large populations. It is postulated that the influence of iron may be catalytic since enrichment with aluminium produced identical growth curves. In addition the final population resulting from enrichment in terms of species composition was shown to be a function of the addition of specific nutrients.

Gulf stream cold core rings: large-scale interaction sites for open ocean plankton communities*

Abstract Gulf Stream cold core rings are major oceanographic features in the northwestern Atlantic Ocean. During formation, cold water of Slope origin and the associated flora and fauna are entrapped within a ring of Gulf Stream water. These systems generally move southwesterly into the Sargasso Sea and are of biological interest because they offer a unique opportunity to assess the relative importance of physical and biotic factors in determining the distribution and abundance of plankton organisms. In effect, the formation and consequent decay of a cold core ring represents a large-scale ecological field experiment wherein major environmental changes are gradually imposed on a plankton community. Four cruises have been made to sample Gulf Stream rings and the surrounding Sargasso Sea. Biomass has been estimated and selected species of Zooplankton, phytoplankton, and midwater fish populations have been assessed. Concurrent hydrocasts have yielded physical-chemical data. Although a ring may remain physically identifiable for as long as two years, decay of the initially distinct biological community appears to be more rapid. A Zooplankton assemblage appears to persist longer than a phytoplankton assemblage. The season of formation appears to be critical in determining the biological changes of a Gulf Stream ring. The rapid demise of the Slope Water species assemblages in the rings may be the result of biological interactions with the Sargasso Sea assemblage initiated by the rapid modification of physical and chemical properties of ring surface waters.

Selective feeding by Balanion sp. (Ciliata: Balanionidae) on phytoplankton that best support its growth

Abstract The planktonic ciliate, Balanion sp., feeds preferentially on certain dinoflagellates when confronted with mixtures of microalgae. The preferred prey are species which support its fastest growth (≈ 3 div./day at 15°C). At high food densities, Balanion can grow as rapidly in algal mixtures which contain its preferred prey as its corresponding monocultures. Balanion are found year-round in estuaries in which dinoflagellates are common but are only occasionally the dominant phytoplankters. Preferential ingestion of suitable dinoflagellate prey may thus increase the growth rate of this ciliate in situ.

Competition for Nutrients by Marine Phytoplankton in Oceanic, Castal, and Estuarine Regions

Fluctuations in the densities of marine phytoplankton species in the open and coastal ocean follow a sequence wherein one or several species may increase in abundance very much without causing a reduction in abundance of other forms. Theoretical calculations of the maximum size of nutrient—depleted zones about the plankton cells show that overlapping of these zones cannot occur at cell densities less than 3 x 108/liter. Since densities rarely exceed 106/liter in the open and coastal ocean, there is no possibility of an abundant species monopolizing the nutrient supply and forcing a less abundant form to extinction. The change from a coccolithophore—dominated plankton in the Sargasso Sea to the diatom—dominated plankton in the coastal water off New York cannot, therefore, be attributed to competition for nutrients by the two types of cells. But in some very shallow estuaries, Great South Bay and Moriches Bay near New York and Salt Pond at Woods Hole, the dominant forms sink considerably more slowly than the coastal and oceanic species and would thus be at an advantage over the latter. Plankton concentrations in the estuaries may come close to or exceed 109/litter, and monopolization of the nutrient supply should aid in the continued dominance of the abundant forms, eventually bringing about the extinction of many of the residual forms. This sequence is considered to be a real possibility in these estuaries and to be the reason for the reduced diversity of species observed there.

The Relationship of the Distribution of the Diatom Skeletonema Tropicum to Temperature

Skeletonema tropicum is distinguished from S. Costatum in possessing a greater number of chromatophores than the latter. S. tropicum is to be found north of the equator as far as latitude 30° in the western Atlantic Ocean, whereas the ubiquitous S. costatum extends into the cold waters farther north. The reason for the limited distribution of S. tropicum, as determined by growth of unialgal cultures, is its inability to live at temperatures less than 13°C.

Downward Transport of Particulate Matter in the Peru Coastal Upwelling: Role of the Anchoveta, Engraulis Ringens

Anchoveta fecal material links production and sedimentation of particulate matter, including organic carbon, organic nitrogen and diatom frustules, in the Peruvian coastal upwelling ecosystem. Longterm fluctuations in anchoveta stock could, therefore, affect the quantity and composition of particulate matter input to the benthos and thereby to the sediment record.

FLAGELLATES FROM BRACKISH WATERS IN THE VICINITY OF WOODS HOLE, MASSACHUSETTS1

The following marine chrysomonads, originally described by Carter, are redescribed: Pseudopedinella pyriforme, Ochromonas oblonga, and Pyrmnesium parvum. Parachrysiclalis n.g. is set up for P. estuariale, with a flattened body and 2 equal flagella inserted in the middle of one side. Redescribed Xanthophy‐cean species include Nephrochloris salina and Olis‐thocliscus luteus. Olisthodiscus carterae and O. magnus are new species, the first distinguished by the position of the flagella and large number of chromatophores, O. magnus by its size (30‐18 μ X 15‐25 μ) and anteriorly inserted but posteriorly trailing flagellum. Among Cryptophyceae, Chroomonas vectensis Carter, Rhodomonas amphioxeia Conrad, and Cryptomonas salina and C. stigmatica Wislouch are redescribed along with Rhodomonas minuta v. apyrenoidosa var. nov. Redescribed Chlorophyta are Bipedinomonas pyriformis Carter, Pyramimonas obovata Carter, P. amylifera Conrad, and what may be Tetra‐selmis suecica (Kylin) Butcher. The loricate, probably colorless Calycomonas gracilis (Lohmann) Wulff is redescribed.

Phytohydrography, Gulf Stream rings, and herbivore habitat contrasts

Abstract The Gulf Stream constitutes a major ecological discontinuity separating two distinct phytohydrographic provinces: the Slope Water and the Northern Sargasso Sea. Differences between phytoplankton assemblages are maximal above well-established seasonal thermoclines. Due to systematic differences in the composition, quantity, distribution, and variability of their phytoplankton assemblages, the upper euphotic zones of the Slope Water and the Northern Sargasso Sea represent very different herbivore habitats. Although the Northern Sargasso Sea has been thought to be a relatively monotonous biogeographic province, within its geographic boundaries Gulf Stream cold core rings constitute largescale floral non-homogeneities. The rings observed differed markedly in species composition from both the Slope Water and the Northern Sargasso Sea. Although species groups isolated by correspondence analysis were not strictly confined to one or another phytohydrographic province they represented ecotypes differing in their apparent ‘responsiveness’ to variation in nutrient concentration.

Attributes of the plankton flora at Bushehr, Iran

The plankton flora on the northeastern coast of the Gulf of Persia consists of many diatom species, the coccolithophores Gephyrocapsa oceanica and Coccolithus huxleyi, and the blue-green alga, Trichodesmium thiebautii. These are prevalent throughout the year and always at low concentrations, with an average maximum in January of 14463 cells/liter and minimum in June of 802/liter. Such comparative constancy suggests that the flora has the attribute of stability. The individual species fluctuate in a patternless, uncorrelated manner, so that the flora is characterized by the attribute of unpredictability. The turbidity of the shallow water reduces the light so that light is usually neither limiting nor inhibitory. There is a small amount of nitrate always available and ample phosphate and silicate. Pure culture studies of several species show growth from about 12° to 34°. The water was 34° in August of 1977. The floras responsiveness to these light, nutrient, and temperature quantities makes possible its recovery to normal after advective disturbance in June 1977.

The four principles of adaptation

There are four principles of adaptation. The first is that if two quite different entities occur under the same condition, then one is adapted and the other is not adapted to this condition. Thus the warm-blooded vertebrate is adapted to year-round temperature in temperate regions because it is behaviorally active year-round, whereas the cold-blooded vertebrate is not adapted to year-round temperature because it is not active year-round. The second principle is that if one entity occurs under two quite different conditions, then it is adapted to one condition but is not adapted to the other condition. Thus the North American forest is adapted to moist conditions in the east and west, but is not adapted to the non-moist, semi-desert regions of the southwest. The third principle is that if one entity is adapted to a second, then the second is adapted to the first. Thus the white spruce was adapted to an expanding locale between 12 000 and 9000 years ago in the mid-west of North America, and this locale was adapted to the spruce. The fourth principle is that two quite different entities occur under two quite different conditions, and one is adapted to its condition and the other is adapted to its condition. Thus, there is a tendency (an entity) toward many boned toes in the paddle limbs of aquatic vertebrates and this is an adaptation to swimming, and there is a tendency toward two or one toes in land vertebrates and this is an adaptation to running. The four principles have a logically valid structure. An example is: if an animal is behaviorally active under year-round temperate temperature, P, then the animal is adapted to year-round temperate temperature, Q; equivalent to: if the animal is not year-round adapted, ∼Q, then the animal is not year-round active, ∼P(P⊃Q)≡(∼Q⊃∼P). Generation of this formula from the axioms of Logic for Mathematicians (Rosser, 1953) p. 530 takes a number of proofs. When it is said that an entity is behaviorally active, it is meant that the entity has the property of being behaviorally active. When it is said that an entity is adapted (to year-round temperature), it is meant that the entity has the property of being adapted, the property of adaptedness (to year-round temperature). This is the philosophical realist view. So by empirical justification and logical and philosophical ramification, an integrated model of the principles of adaptation is sought.