Seasonal growth and reproduction of estuarine fucoid algae in New England

Estuarine populations of Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. var. spiralis Farlow from the Piscataqua River of the Great Bay Estuary System (New Hampshire-Maine) showed their maximum growth during the spring and fall of two consecutive years. The maximum growth rates (in terms of elongation) for Ascophyllum and Fucus were 3.5 and 3.6 cm/month, respectively, during 1973, and 3.2 and 2.3 cm/month in 1974. The average length of whole Fucus fronds showed a trend towards longer plants during the early spring and late summer-fall, while the average weight was significantly greater in the spring and early summer. Ascophyllum showed a distinct reproductive periodicity, with a maximum in March or April of both years; after the spring period of maximum reproduction, the receptacles dehisced simultaneously and the plants were vegetative during the summer. The reproductive periodicity of Fucus was not so distinct as that of Ascophyllum; even so, its maximum reproduction was in April of both years. The level of reproduction for Ascophyllum populations was three times greater in 1974 than in 1973. The reproduction and growth of the two fucoid algae are related to seasonal variations in temperature and light.     

Ecological studies of economic red algae. III. Growth and reproduction of natural and harvested populations of Gigartina stellata (Stackhouse) batters in New Hampshire

The growth in situ of populations of Gigartina stellata (Stackhouse) Batters has been recorded at three New Hampshire locations and correlated with seasonal and spatial variations of surface salinity, temperature, and nutrients. Annual growth began between February and May, depending upon the location and its hydrographic regime. Gigartina populations reached maximum biomass and size in August and September, and a general decrease in both occurred during the reproductive period from October to February. The period of fastest growth coincided with increasing summer temperatures, while maximum carpospore release occurred during the period of decreasing (coldest) temperatures. The largest plants and maximum biomass of Gigartina were found on the open coast (at a semi-exposed site) while smaller plants and reduced biomass were evident within the Great Bay Estuary System. Salinity is a dominant factor influencing both the local distribution and growth of the plant. Gigartina is primarily restricted to the littoral zone, and its maximum length and biomass occur between +0.45 and +1.0 m above M.L.W.     

The growth,reproductive phenology,and longevity of non-tide-pool Fucus distichus (L.) powell in New England

The growth, reproductive phenology, and longevity of in situ populations of Fucus distichus L. ssp. edentatus (De la Pylaie) Powell and F. distichus L. ssp. evanescens (C. Agardh) Powell were evaluated in New England. Both subspecies exhibited maximum growth during early summer, a slight decline in late summer, and a brief resurgence in the early fall. The maximum growth rates (in terms of elongation) for F. distichus ssp. edentatus and ssp. evanescens were 3.5 and 3.7 cm/28 days, respectively. Populations of both subspecies showed a distinct bimodal reproductive periodicity, with maxima in the spring and fall. Even so, individuals were either reproductive in the spring or fall but never in both seasons. After reproduction, receptacles dehisced and plants either became vegetative or died. Higher rates of plant attrition were observed during periods of reproduction than during non-reproductive periods.     

Seasonal influx and decomposition of autochthonous macrophyte litter in a north temperate estuary

An 18-month study was undertaken to determine the seasonal contribution and detrital processing of autochthonous plant litter in the Great Bay Estuary System of New-Hampshire-Maine, USA and adjacent open coast. Four species were studied: the halophytes, Spartina alterniflora Loisel. and Zostera marina L. and the seaweeds, Ascophyllum nodosum (L.) Le Jolis and Fucus vesiculosus L. v. spiralis Farlow. Monthly strand line collections at estuarine and open coastal sites provided information on the seasonal influx of litter derived from each species. Detrital inputs from S. alterniflora and Z. marina were maximal in the spring and summer, respectively. Seaweed litter was abundant (35 to 85% of the total strand line) throughout the year. The seaweeds contributed 1 to 3 times as much detrital material as the vascular plants within the Estuary, and 50 times as much on the open coast. In situ measurements of decomposition, using nylon, mesh bags, were made for each species under several environmental conditions. Seaweeds decomposed 3 to 10 times faster than vascular plant litter under similar conditions. Decomposition rates and changes in the nutrient content of litter were dependent on surrounding environmental conditions. Continual nutrient depletion occurred in litter within the strand line. Nitrogen and phosphorus enrichment were observed under submerged conditions and were attributed to microbial activity and rapid leaching of carbonaceous substrates. A computer simulation model was developed to validate the field data and to predict seasonal detrital carbon input by each species. The significance of autochthonous input is discussed in relation to other detrital sources.     

Factors controlling the lower limits of fucoid algae on the shore

Field and culture studies on fucoid alga of the upper shore showed that their lower limits of distribution were determined largely by interspecific competition. Pelvetia canaliculata (L.) Dcne. et Thur., which is strictly confined to the highest algal zone, grew much more slowly, both in culture and on the shore, than did Fucus spiralis L., which occupies the zone immediately below Pelvetia. When transplanted to the Fucus spiralis zone, macroscopic Pelvetia thalli grew normally, but Pelvetia zygotes which germinated within this zone reached macroscopic size only when competing Fucus spiralis was repeatedly removed.Both species required high light levels to grow in culture, yet their embryos remained viable for long periods in total darkness. Thus, Pelvetia cannot grow in the shade of Fucus spiralis, but actual removal of the Pelvetia germlings from the Fucus spiralis zone must be affected by some other factor.F. spiralis grew vigorously when transplanted to M.T.L., a level at which it is normally rare. In culture, its embryos grew more slowly than those of the species found lower on the shore such as F. vesiculosus L. and F. serratus L.; hence interspecific competition may again be involvedYoung Ascophyltum nodosum (L.) Le Jol. plants grew almost as slowly as those of Pelvetia, yet Ascophyllum dominates the middle shore. In culture it showed only slightly greater tolerance of low light intensity than other fucoids but, unlike Pelvetia, persisted and grew beneath a Fucus canopy in the field. The possibility that differences in life history and palatibility to grazing molluscs contribute to the disparate competitive abilities of Pelvetia and Ascophyllum is discussed.     

Factors controlling the upper limits of fucoid algae on the shore

Year-round observations on the condition of intertidal seaweeds growing in situ on the shore, show that the upper limits of the zones characterized by Pelvetia canaliculata (L.) Done et Thur., Fucus spiralis L. and Ascophyllum nodosum (L.) Le Jol. were periodically pruned back by environmental conditions. The uppermost plants of each species showed clear signs of tissue damage 21 to 28 days after a time when drying conditions coincided with neap tides which exposed the plant to aerial conditions for long periods. High air temperatures aggravated the damage, but neither frost nor prolonged rain had any obvious adverse effects. On spring tides the plants were wetted every day and no damage resulted regardless of the weather.These species clearly all reach up to their physiological limits on the shore investigated, but presumably Fucus vesiculosus L. and F. serratus L. do not, for they were never observed to show signs of tissue damage attributable to exposure to air. Transplant experiments did, however, prove that F. serratus cannot survive in the F. spiralis zone and nor can F. spiralis persist in the Pelvetia canaliculata zone.Laboratory experiments also demonstrated that the ability to tolerate desiccation and then to resume photosynthesis and growth when re-submerged was greatest in P. canaliculata, the species found highest on the shore, and was progressively less in species inhabiting successively lower levels.     

Annual variation in growth rate of perennial littoral fucoid algae from the west coast of Norway

The growth of apical segments of six perennial fucoid littoral algae (Pelvetia canaliculata (L.) Dec. et Thur., Ascophyllum nodosum (L.) Le Jol., Fucus spiralis L., F. vesiculosus L., F. serratus L. and F. distichus L. subsp. edentatus (Pyl.) Powell) was measured at approximately monthly intervals during 1 year.In winter, elongation was limited by temperature and light. Maximum growth in May–June coincided with minimum N concentration in the seawater, but with high N concentration in the apical tissue. Throughout summer, both growth and tissue N concentration decreased, indicating that the growth was nutrient limited.A close linear correlation is indicated between elongation and weight increase in apices of A. nodosum.     

Competitive interactions between Fucus spiralis L. and F. vesiculosus L. (Fucales,Phaeophyta)

Fucus spiralis forms a conspicuous belt in the upper intertidal on rocky shores of the NW Atlantic. The objective of this study was to determine whether competition among congeners plays a role in restricting the distribution of F. spiralis to the upper shore. A replacement series design was used to test the growth performance of F. spiralis and F. vesiculosus in monocultures and in mixtures set up in the mid shore level on an exposed rocky coast. For F. spiralis and F. vesiculosus, all individual and relative crowding coefficients were < 1 and > 1, respectively. Hence, F. vesiculosus succeeded relative to F. spiralis in all mixtures tested. This finding was confirmed by graphical analysis. Ratio diagrams showed that the outcome of long term interaction among the species is extinction of F. spiralis. The results lead to the conclusion that interaction among congeners is a major determinant of the restricted distribution of F. spiralis.     

Abundance of Latrodectus katipo Powell, 1871 is affected by vegetation type and season

The seasonal abundance of Latrodectus katipo Powell, 1871, a declining spider species endemic to coastal dunes in New Zealand, was observed in two different plant communities: an endemic sedge, Ficinia spiralis A. Rich. and an exotic grass, Ammophila arenaria (L.) Link. Using artificial cover objects (ACOs), presence/absence data was collected for L. katipo in the two plant communities. ACOs were positioned at Kaitorete Spit, which supports a healthy population of L. katipo, adjacent to F. spiralis or A. arenaria. ACOs were checked over four seasons. L. katipo were found significantly more often in ACOs placed next to F. spiralis as opposed to A. arenaria and its presence was highest in summer. Conserving L. katipo will involve reducing the amount of A. arenaria in New Zealand’s sand dunes. Studies monitoring L. katipo population dynamics should do so in summer when they are most abundant.     

Comparative studies on the biology of nerita atramentosa Reeve, bembicium nanum (Lamarck) and cellana tramoserica (Sowerby) (gastropoda: Prosobranchia) in S.E. Australia

Populations of three coexisting intertidal gastropods, Nerita atramentosa Reeve, Bembicium nanum (Lamarck) and Cellana tramoserica (Sowerby), were sampled from a shore in Botany Bay, New South Wales, from July 1972 to September 1973. The recruitment and growth rates of each species were analysed from size frequency distributions. Mortality of each age cohort, and longevity, were estimated from analyses of the densities of Nerita atramentosa and Bembicium nanum.Nerita atramentosa showed no significant mortality during the first two years on the shore, but high mortality (at an instantaneous rate of 0.084 deaths/individual/month) after reaching the age of reproductive maturity, which was 20 months from settlement and at a mean shell-length of 13.5 mm. No growth could be detected after reproductive maturity was reached. Longevity of N. atramentosa was estimated as 3–5.5 years. Bembicium nanum juveniles showed higher mortality (at an instantaneous rate of 0.233 deaths/individual/month) than reproductively mature animals (0.060 deaths/individual/month). Reproductive maturity was reached at a mean shell-breadth of 11.0mm, i.e., about ten months after settlement on the shore. Longevity was estimated as from 4–8 years. Cellana tramoserica showed different growth patterns depending on the time of settlement.The three species showed different patterns of growth and life history relating to variable recruitment (which was demonstrated in all three species) and different rates of mortality of age cohorts.     

Interactions of Patella and macroalgae with settling Semibalanus balanoides (L.)

Biological interactions affecting densities of settling and newly-settled Semibalanus balanoides (L.) have been investigated by manipulative field experiments on the Isle of Man.The effects of sweeping by fucoid clumps of different species and Patella browsing have been compared on moderately-exposed shores. Patella allowed barnacle settlement by preventing growth of competing green algae, but reduced post-settlement densities. Small clumps of Fucus spiralis L., F. vesiculosus L, and F. serratus L. all reduced settlement considerably more so than limpets. F. serratus had the greatest sweeping effect.Interactions between macroalgae and Semibalanus balanoides have been investigated at all levels on sheltered shores and low down on more exposed shores. In the Fucus spiralis and F. vesiculosus zones, post-settlement numbers were higher than in adjacent areas where the canopy was removed. Barnacles did not settle readily in the Ascophyllum zone in either experimental or control areas. Settlement occurred in the upper part of the Fucus serratus zone in experimental areas where the canopy was removed but not in control areas. No settlement occurred in either treatment or control areas lower in the F. serratus zone. At all levels on the shore fucoid canopies seemed to reduce cyprid settlement, but the effect was greatest amongst F. serratus where there was total prevention. High on the shore the effect of enhanced post-settlement survival under the canopy outweighs reduction of cyprid settlement thus there are greater numbers in the controls. Competition with red algal turfs was shown to set the lower limit of the barnacle zone on a vertical pier face.     

Microbial herbivory on the brown tide alga, Aureococcus anophagefferens: results from natural ecosystems, mesocosms and laboratory experiments

Experiments were conducted with natural plankton assemblages from two areas in Great South Bay (GSB) and the Peconic Bays Estuary System, NY, to compare the rates of growth and pelagic grazing mortality of Aureococcus anophagefferens with co-occurring phytoplankton. We hypothesized that A. anophagefferens would experience low mortality rates by microbial herbivores (relative to feeding pressure on other algae) thus providing it with a competitive advantage within the phytoplankton community. In fact, substantial rates of mortality were observed in nearly every experiment in our study. However, mortality rates of A. anophagefferens were less than intrinsic growth rates of the alga during late spring and early summer in Great South Bay, resulting in positive net growth rates for the alga during that period. This timing coincided with the development of a brown tide in this estuary. Similarly, growth rates of the alga also exceeded mortality rates during bloom development in natural plankton assemblages from the Peconic Bays Estuary System held in mesocosms. In contrast to the situation for A. anophagefferens, growth rates of the total phytoplankton assemblage, and another common picoplanktonic phytoplankter (Synechococcus spp.), were frequently less than their respective mortality rates. Mortality rates of A. anophagefferens in both systems were similar to growth rates of the alga during later stages of the bloom. Laboratory studies confirmed that species of phagotrophic protists that consume A. anophagefferens (at least in culture) are present during brown tides but preference for or against the alga appears to be species-specific among phagotrophic protists. We conclude that two scenarios may explain our results: (1) protistan species capable of consuming the brown tide alga were present at low abundances during bloom initiation and thus not able to respond rapidly to increases in the intrinsic growth rate of the alga, or (2) the brown tide alga produced substance(s) that inhibited or retarded protistan grazing activities during the period of bloom initiation. The latter scenario seems less likely given that significant mortality of A. anophagefferens was measured during our field study and mesocosm experiment. However, even a minor reduction in mortality rate due to feeding selectivity among herbivores might result in a mismatch between growth and grazing of A. anophagefferens that could give rise to significant net population growth of this HAB species. Either scenario infers an important role for trophic interactions within the plankton as a factor explaining the development of brown tides in natural ecosystems.     

The species composition and quantitative distribution of the diatom genus Pseudo-nitzschia H. Peragallo, 1990 in Russian waters of the Sea of Japan and the Sea of Okhotsk

This paper studies the species composition and quantitative distribution of diatoms that belong to the genus Pseudo-nitzschia in the Russian waters of the Sea of Japan and the Sea of Okhotsk. In total, 11 species of this genus were found in the area, including 7 that are known as being potentially toxic. The highest concentrations of Pseudo-nitzschia microalgae (1.4 × 10⁶–2.7 × 10⁶ cells/L) were found in the summer and autumn in the Peter the Great Bay of the Sea of Japan and the lowest concentrations (2.5 × 10²–1 × 10⁴ cells/L) were found in the Sakhalinsky and Akademiya bays of the Sea of Okhotsk. The species diversity of potentially toxic diatoms was greatest (seven species) and the cell concentrations highest (over 6 × 10⁵ cells/L) in the Peter the Great Bay, Sea of Japan, and in the Aniva Bay, Sea of Okhotsk. The density of potentially toxic species was highest near the northeastern coast of Sakhalin Island, in the Amur River estuary, and in adjacent waters. This paper also presents geographical distribution maps of Pseudo-nitzschia species and maps of the density distribution of potentially toxic microalgae over the studied area and identifies potential amnesic shellfish poisoning areas.     

Rhodobacteraceae on the marine brown alga Fucus spiralis are abundant and show physiological adaptation to an epiphytic lifestyle

Macroalgae harbour specific microbial communities on their surface that have functions related to host health and defence. In this study, the bacterial biofilm of the marine brown alga Fucus spiralis was investigated using 16S rRNA gene amplicon-based analysis and isolation of bacteria. Rhodobacteraceae (Alphaproteobacteria) were the predominant family constituting 23% of the epibacterial community. At the genus level, Sulfitobacter, Loktanella, Octadecabacter and a previously undescribed cluster were most abundant, and together they comprised 89% of the Rhodobacteraceae. Supported by a specific PCR approach, 23 different Rhodobacteraceae-affiliated strains were isolated from the surface of F. spiralis, which belonged to 12 established and three new genera. For seven strains, closely related sequences were detected in the 16S rRNA gene dataset. Growth experiments with substrates known to be produced by Fucus spp. showed that all of them were consumed by at least three strains, and vitamin B₁₂ was produced by 70% of the isolates. Since growth of F. spiralis depends on B₁₂ supplementation, bacteria may provide the alga with this vitamin. Most strains produced siderophores, which can enhance algal growth under iron-deficient conditions. Inhibiting properties against other bacteria were only observed when F. spiralis material was present in the medium. Thus, the physiological properties of the isolates indicated adaption to an epiphytic lifestyle.     

A genetic analysis of the beluga whale Delphinapterus leucas (Cetacea: Monodontidae) from summer aggregations in the Russian Far East

The genetic structure of four summer aggregations of the Beluga Whale, Delphinapterus leucas, in Sakhalin Bay and Udskaya Bay, off the western coast of Kamchatka in the Sea of Okhotsk and in the Anadyr Estuary of the Bering Sea was analyzed through nucleotide sequencing of the mtDNA control region and detection of the allelic composition of nine microsatellite loci in nuclear DNA. It has been shown that each of the aggregations features a unique set of maternal lines, which indicates a high degree of philopatry in this species. Beluga whales of the Anadyr Estuary are genetically isolated from those of the Sea of Okhotsk. Beluga whales of the summer aggregations of Sakhalin Bay and those from Udskaya Bay share a common gene pool and belong to a single population, while the whales that summer off western Kamchatka with great consistency may be attributed to a different population. Comparison of nucleotide sequences of the mtDNA in beluga whales from various waters of the Russian Far East and North America allowed us to propose a hypothesis about how the structure of beluga whale populations formed in the North Pacific during the postglacial period.     

Life History of the Barnacle Balanus Amphitrite Darwin and Its Role in Fouling Communities of Peter the Great Bay, Sea of Japan

The life history of the barnacle Balanus amphitrite Darwin and its role in fouling communities of Golden Horn Bay (Peter the Great Bay), which is subjected to thermal pollution, were studied. The warm-water B. amphitrite occurs as a common minor species on operational vessels and waterworks in Peter the Great Bay, where it was brought by ocean-going ships operating on Russia–Japan lines. Even in the conditions of the higher temperature regime of Golden Horn Bay, the reproductive season of B. amphitrite is confined to the summer and autumn months. The adult individuals brought by ships in summer produce 2–3 generations of larvae. The development of larvae and their settling on the substrate occurs from August to October within a broad temperature range from 22.5 up to 12°C. Even in the low temperatures of Golden Horn Bay the larvae attain a greater size than those in tropical and subtropical waters. The juveniles have time to reach maturity and to produce their own progeny, but most often they perish with winter drop in the water temperature. It was shown that in Peter the Great Bay there is dependent population of B. amphitrite inhabiting the anthropogenic substrates only in the warm season: water works, idle vessels, and operational offshore vessels. The water temperature is the limiting factor of successful acclimation of that species.     

Trichinella spiralis: Comparison with an Arctic isolate

The muscle phase of Trichinella spiralis and of Trichinella sp. isolated in the Arctic was compared in experimental and wild animals. Reproductive capacity indices (RCI) of the Trichinella sp. isolate were significantly lower in laboratory rodents but were similar to T. spiralis in wild rodents. Sprague-Dawley rats were the most refractory to the Trichinella sp. isolate of all laboratory rodents. Outbred strains of mice were more susceptible to both T. spiralis and the Trichinella sp. isolate than inbred strains of mice. T. spiralis muscle larvae survived longer in mice and the survival of both T. spiralis and the Trichinella sp. isolate larvae was higher in female mice. While single pair interbreeding experiments showed reproductive isolation between T. spiralis and the Trichinella sp. isolate, multiple pair and transplant breeding experiments showed reproductive compatibility. Male and female infective larvae of T. spiralis and the Trichinella sp. isolate differed morphometrically, but a convergence in size of worms was observed after prolonged passages of the parasites in mice. Passaging history of the isolate and host species was found to have a significant effect on Trichinella morphology. It is proposed that the Trichinella sp. isolate is a physiological variant of T. spiralis and not a distinct species.     

EFFECTS OF ICE ON ASCOPHYLLUM NODOSUM WITHIN THE GREAT BAY ESTUARY SYSTEM OF NEW HAMPSHIRE-MAINE12

The, effects of ice on Ascophyllum nodosum (L.) Le Jolis within the Great Bay Estuary System of New Hampshire-Maine, U.S.A. were assessed during the winter of 1980–81. Approximately 50% of the plants late fall standing crop, or an estimated 136 tonnes dry weight, was removed by ice-rafting. Pieces of Ascophyllum removed averaged 22 cm in length, 15 g in fresh weight and generally represented 2–3 years of growth. Although the winter of 1980–81 wax somewhat extreme, a similar pruning process probably occurs each year contributing to the characteristic bushy habit of attached inner estuarine plants. Ascophyllum fragments rafted in ice and deposited into salt marshes are suggested as a major source of the, ecad scorpioides (Hornemann) Hauck.     

Trichinella spiralis: comparison of stages in host intestine with those of an Arctic Trichinella sp

The intestinal phase of Trichinella spiralis and of Trichinella sp. isolated in the Arctic were compared in experimental animals. Reproductive capacity, pathogenicity, distribution, and persistence of adults in the small intestine, morphological measurements, and release of newborn larvae in vitro were examined. Numerous passages of 40 days each for T. spiralis and the Trichinella sp. isolate in mice did not affect reproductive capacity, distribution of adults in the small intestine, and size of worms. Reproductive capacity index for T. spiralis, I = 151.27 ± 27.30 was significantly higher compared to the Trichinella sp. isolate index, I = 63.46 ± 19.34. The Trichinella sp. isolate was more pathogenic to mice and wild rodents compared to T. spiralis during the intestinal phase. Both parasites were located in the anterior part of the small intestine but the position of T. spiralis adults (P = 17.08) differed from position of the Trichinella sp. isolate adults (P = 23.46) in the small intestine. Intestinal phase of T. spiralis was longer (20 days) compared to the Trichinella sp. isolate (15 days) but sex ratios (:♂) were similar for both parasites. T. spiralis females released significantly higher numbers of larvae in vitro/24 hr compared to the Trichinella sp. isolate. Release of larvae was continuous during the intestinal phase and the average fecundity for T. spiralis was 335 larvae/female and for the Trichinella sp. isolate 114 larvae/female. Adults of T. spiralis and the Trichinella sp. isolate were morphologically indistinguishable and did not differ in size. A comparative index for the intestinal phase is proposed for comparison of any Trichinella spp. isolates and standard T. spiralis.     

Can otoliths of <Emphasis Type="Italic">Genidens genidens</Emphasis> (Cuvier 1829) (Siluriformes: Ariidae) reveal differences in life strategies of males and females?

Determination of the growth parameters of a species is an indispensable requirement for understanding its biology and consequently the management of its fishery. In fisheries science, calculations of longevity, mortality rates and stock-assessment models depend on the availability of growth data. Genidens genidens, one of the most common ariid species in Brazil, is a potential sentinel species for biomonitoring in Guanabara Bay, one of the country’s most degraded estuarine ecosystems. The present study investigated the growth parameters of G. genidens, providing supporting information for its management. Individuals were measured, sexed, and the number of rings in the lapillus otolith counted. The periodicity in the formation of the rings was determined by the monthly ratio of the edge type. Individuals from 0 to 11.5 years old were captured, including some that were older than previously reported. Our results showed that this species forms two growth rings per year, one in summer and the other in winter; the summer ring is formed one month later in males than in females, due to the period of oropharyngeal incubation of the offspring. Sexual dimorphism was also observed in the growth rate: males grow faster, and consequently reach smaller sizes than females. We can conclude that the parental care carried out by males and the high energy expenditure in forming the large oocytes by females mark the otoliths and reveal life-cycle particularities differently in each sex.