Responses of the sand dollar <Emphasis Type="Italic">Scaphechinus mirabilis</Emphasis> to extreme environmental changes

The survival ability of the adult sand dollar Scaphechinus mirabilis (Agassiz) in varying environments was studied. In an experiment on a hard substrate, 88% of the animals survived for 40 days (August–September) during variation of sea water temperature from 21.0 to 16.5°C and variation of salinity from 33.3 to 31.5‰. At 17°C, the salinity tolerance range was 34–24‰. At the same temperature. 100% of the animals remained alive for 14 days within a salinity range from 34 to 18‰; at 16 and 14‰ the ratio of surviving sea urchins was 30 and 20% respectively. Thus, S. mirabilis has considerable adaptive capabilities and is able to survive for a long time under extreme environmental changes.     

Adaptive responses of embryos and larvae of the heart-shaped sea urchin <Emphasis Type="Italic">Echinocardium cordatum</Emphasis> to temperature and salinity changes

The combined effects of temperature (8, 12, 14, 17, 20, 22 and 25°C) and a salinity decrease from 36 to 12‰ on the development of the sea urchin Echinocardium cordatum (Pennant) were studied. Embryonic development proved to be the process most vulnerable to a salinity decrease. It was completed successfully at 8–20°C within a narrow salinity range of 36–28‰ Larvae at the most resistant stage, the blastula, survived at 12–22°C and a salinity of 36–18‰. Larvae at the most sensitive stage, pluteus I with the first pair of arms, died even in a favorable environment, a temperature of 17–20°C and a salinity of 34–28‰. That may be related to qualitative alterations during skeleton formation and to transition to phytoplankton feeding. The resistance of larvae to variations in environmental factors gradually increased in the pluteus II and III stages; however, it significantly decreased before the settling of the larvae. Larvae that were 37 days old survived at a temperature of 14–20°C within a salinity range of 36–22‰ and at 22 and 25°C, they survived at a salinity of 36–24‰; however, all the larvae became abnormal at 25°C. The larvae settled earlier on sand inhabited by adult individuals of E. cordatum than on sand from other locations, and they settled faster at 20–25°C, than at 14 and 17°C. The juveniles, if lacking an opportunity to burrow in the sand, died within 14 days after settling.     

The effect of temperature-salinity combinations on the functional well-being of adult Lytechinus variegatus (Lamarck) (Echlnodermata,Echinoldea)

The activity coefficient (1000/righting time in sec) was measured to indicate the functional state of Lytechinus variegatus (Lamarck) after exposure to combinations of temperature (22°, 28°, and 34°C) and salinity (25, 30, 35, and 40 ‰). Environmental levels of these variables were 30–33°C and 34–35 ‰. The results indicate that the species lives closer to the upper than lower lethal limits of temperature and salinity. The maximal activity coefficient (18 ± 8) was at 28°C and 35 ‰. A reduction in salinity was probably responsible for a recent mass mortality of the echinoid reported in the eastern Gulf of Mexico.     

Temperature,salinity tolerance,and buoyancy during early development and starvation of Clyde and North Sea herring,cod, and flounder larvae

Tolerance limits, at which 50% of larvae could survive high temperature and low salinity for 24 h, were determined for the yolk-sac larvae of Clyde and North Sea herring (Clupea harengus L.), cod (Gadus morhua L.) and flounder (Platichthys flesus L.) during early development and starvation. Clyde and North Sea herring, cod and flounder from hatching to the end of the yolk-sac stage, could withstand 21–23.5 °C, 20.5–23 °C, 15.5–18 °C and 21.5–24°C, respectively. The temperature tolerance was reduced by about 3.5–4 °C for Clyde herring and cod, 4–4.5 °C for North Sea herring and 8–8.5 °C for flounder when the larvae reached the point-of-no-return (PNR, when 50% of larvae, although still alive, are no longer strong enough to feed). The lowest salinity tolerance between hatching and the end of yolk-sac stage was 1–1.5‰ for Clyde and North Sea herring, 2–3‰ for cod and 0–1‰ for flounder. In no instance was there a loss of tolerance to low salinity during starvation. In fact, tolerance improved somewhat until the larvae became moribund. At hatching Clyde and North Sea herring larvae were negatively buoyant with a sinking rate of 0.35–0.4cm · s⁻¹ which steadily decreased until the larvae became moribund. Cod and flounder larvae, however, were positively buoyant at hatching but became progressively less buoyant and, by the end of the yolk-sac stage they were negatively buoyant with a sinking rate of 0.06–0.07 cm · s⁻¹. This sinking rate then decreased slightly until the PNR stage. The low salinity tolerance of all three species varied in a similar fashion to buoyancy.     

The combined effect of temperature and salinity on development of the sea star Asterina pectinifera

The effect of various combinations of temperature, which increases from 14°C up to 25°C in the summer season, and salinity, which varies from 34 to 12‰ in the early stages of development of the sea star Asterina (= Patiria) pectinifera (Müller et Troschel) from Vostok Bay, Sea of Japan, was studied. The most vulnerable process in the early ontogenesis of A. pectinifera is its embryonal development, which is completed successfully within narrow ranges of temperature (20–22°C) and salinity (34–26‰). The ability of gametes to fertilize was retained in wider ranges of temperature and salinity. The dipleurula was the most responsive of the larval stages; the resistance of blastula, bipinnaria, and brachiolaria at ages of 12.5 and 15.5 days was almost the same for fluctuations of temperature from 14 up to 25°C and salinity from 34 to 18 and 16‰ Settling of the brachiolaria and completion of metamorphosis were also responsive to variations in the environmental factors. Settling of the larvae was faster at 17°C without illumination (on the 22nd–24th days of development) than at 22°C with the day-night mode (27th–28th day of development). The lack of light apparently had a positive effect on the settling of the brachiolaria.     

The combined effects of temperature,salinity, and declining oxygen tension on oxygen consumption in the marine pulmonate Amphibola crenata (Gmelin, 1791)

Oxygen consumption of Amphibola crenata (Gmelin) was measured in various salinity-temperature combinations (< 0.1‰ to 41‰ salinity and 5 to 30°C) in air, and following exposure to declining oxygen tensions. In all experimental conditions, respiration varied with the 0.44 power of the body weight (sd = 0.14). The aquatic rate was consistently higher than the aerial rate of oxygen consumption, although at 30 °C the two rates were similar. Oxygen consumption increased with temperature up to 25 °C in all salinities; the lowest values were recorded at temperatures below 10 °C and at 30 °C in the most dilute medium. At all exposure temperatures, the oxygen consumption of Amphibola decreased regularly with salinity down to 0.1 ‰, and following exposure to concentrated sea water (41‰). Salinity had the least effect at 15 °C which was the acclimation temperature. In general, all of the temperature coefficients (Q₁₀ values) were low, < 1.65. However, Q₁₀ values above 2.8 were recorded at a salinity of 17.8‰ between 10 and 15 °C. Oxygen consumption of all size classes of Amphibola was more temperature dependent in air than in water and small individuals show a greater difference between their aerial and aquatic rates than larger snails. The rates of oxygen consumption in declining oxygen tensions were expressed as fractions of the rates in air saturated sea water at each experimental salinity-temperature combination. The quadratic coefficient B₂ becomes increasingly more negative with both decreasing salinity and temperatures up to 20 °C. At higher temperatures (25 and 30 °C) the response is reversed such that O₂ uptake in snails becomes increasingly independent of declining oxygen tensions at higher salinities. On exposure to a salinity of 4‰, Amphibola showed no systematic response to declining oxygen tension with respect to temperature. The ability of Amphibola to maintain its rate of oxygen consumption in a wide range of environmental conditions is discussed in relation to its potential for invading terrestrial habitats and its widespread distribution on New Zealand's intertidal mudflats.     

Temperature and salinity effects on the respiratory metabolism of the first zoeal stage of Macrobrachium holthuisi Genofre & Lobão (decapoda: Palaemonidae)

Oxygen consumption rates of stage I Macrobrachium holthuisi Genofre & Lobão zoeae were measured in 24 different temperature and salinity combinations using Cartesian diver microrespirometers. Metabolic rates varied little with salinity at 15°C while at 20°C a marked elevation occurred in 0 and 35‰ At 25°C, a slight elevation occurred in 0‰; rates remained constant, however, in the other salinities. At 30°C, respiratory rates were similar to those recorded at 25°C except for decreases at 0 and 28‰ salinity. Q₁₀ values in the different salinities were usually highest between 15 and 20°C. Statistical analyses showed that while both temperature, salinity and their interaction significantly influenced larval respiratory rates, temperature had the more pronouced effect. Larval metabolism is salinity independent over the salinity range encountered in the larval biotope (7–21‰) at temperatures of 15–30°C.     

Exposure of goldsinny, rock cook and corkwing wrasse to low temperature and low salinity: survival, blood physiology and seasonal variation

Wrasse used as cleaner fish with farmed Atlantic salmon Salmo salar can be subjected to large and rapid temperature and salinity fluctuations in late autumn and early winter, when summer-warmed surface water is affected by early snowmelt episodes. Because of their containment in sea cages, wrasse which are essentially acclimated to summer temperatures may be rapidly exposed to winter conditions. Short-term tolerance of low temperature and low salinity by three species of wrasse, goldsinny Ctenolabrus rupestris rock cook Centrolabrus exoletus corkwing Crenilabrus melops caught during the summer, and winter-caught corkwing, was investigated. A 3–day period at 30 or 32‰ salinity and temperature 8, 6 or 4° C (for summer-caught fish; 4° C only for winter-caught) was followed by a decline in salinity to 24, 16 or 8‰ over c. 36 h, followed by a further 24 h at these salinities held constant, at each of the three temperatures. Controls in 30 or 32‰ were maintained at 8, 6 or 4° C. Mortality of summer-caught corkwing and rock cook was high at 4° C, whereas the influence of salinity on mortality was small. Mortality of goldsinny was low or zero in all treatments. Surviving corkwing and rock cook after 3 days at 4° C and 32‰ salinity had elevated plasma osmolality: in summer-caught corkwing, plasma [Cl°] and [Na⁺] were high, whereas in rock cook only [Na⁺] was high. Haematocrit was low in summer-caught corkwing, high in rock cook. In survivors of all three species at the end of the experiment, values of all these parameters were comparable with those of fish at the beginning of the experiment, except that survivors at low salinity (8, 16‰) had low plasma osmolality, at all temperatures, and in surviving rock cook in these treatments haematocrit was high and plasma [Cl^?] was low. Winter-caught corkwing had higher osmolality, [Na⁺] and [Cl^?] than summer-caught corkwing; there was no difference in haematocrit. Survival of wintercaught corkwing exposed to four salinities at 4° C was much higher than that of summercaught corkwing under the same conditions. Little change in blood physiology was recorded for winter-caught corkwing, with only fish subjected to 8‰ and 4° C showing signs of osmoregulatory stress. The interspecific and seasonal differences in survival and blood physiology at low temperature and low salinity are discussed in relation to wrasse survival over winter, both in the field and in salmon farms.     

Adaptivity of the bivalve Mytilus trossulus larvae to short-and long-term changes in water temperature and salinity

Adaptivity to short-term and long-term changes in water temperature and salinity was studied in larvae of the bivalve mollusk Mytilus trossulus. It was shown that water temperature of 4°C mostly suppressed growth and development of larvae. A temperature of 20°C promoted an enhanced larval growth and development. Though a temperature of 20°C caused enhanced larval growth, the temperature was not optimal, while its effect caused quality diversity of larval development, owing to the difference in their growth rates. Such diversity was not observed at moderate temperatures of 10 and 15°C. At 20°C, fast-growing mussel larvae were very sensitive to temperature drops. Growth of slowly-growing individuals did not depend on temperature in the range of 10 to 20°C. Daily temperature variations by 3–8°C did not markedly affect growth and development of the larvae. A continuous 24-h exposure to temperature drops by 3–8°C did not influence these very important physiological characteristics either. A salinity drop down to 8‰ exerted an adverse effect only on early larvae. Later on, the larvae showed their ability to adapt to such a strong desalination. The negative effect of reduced salinity (to 8‰) upon mussel larvae was increased at a temperature increase to 20°C.     

Effects of temperature and salinity on the eggs and early larvae of Caranx mate (Cuv. & Valenc.) (pisces: carangidae) in Hawaii

Eggs and larvae of the carangid fish, Caranx mate (Cuv. & Valenc.), were incubated at various temperature (17.2 to 33.1 °C) and salinity (10 to 42 ‰) combinations in five experiments. The following rates were directly proportional to temperature: embryonic development, yolk absorption, eye and jaw development, and increase in length. Unfed C. mate larvae attained a maximum size at 25 °C and 20 ‰ Eyes and jaws of larvae were functional by the end of the yolk sac stage at all temperature and salinity levels tested.Hatching success and larval survival at the end of the yolk sac stage were generally greater than 50 % between 22° and 32°C. Hatching success and larval survival at the end of the yolk sac stage were reduced at salinity extremes, especially in low temperature-low salinity and high temperature-high salinity combinations. The frequency of morphological abnormalities was also high at extreme temperatures and salinities.The incipient upper thermal TL_m for unfed C. mate larvae acclimated to 23.8°C increased from 31.5°C for newly hatched larvae, to 34.2°C for 72 h larvae, but decreased to 32.0°C for starving larvae after the exhaustion of the yolk supply.     

Responses of Embryos and Larvae of the Starfish <Emphasis Type="Italic">Asterias amurensis</Emphasis> to Changes in Temperature and Salinity

We studied the effects of different combinations of temperature (5, 10, 14, 17, 20, and 22°C) and salinity (from 32 to 8‰) on the development of the starfish Asterias amurensis Lutken from Vostok Bay, Sea of Japan. Embryonic development is the most vulnerable stage; it passes successfully at 10–17°C and the salinity range of 32 to 26‰. Blastulae are the most tolerant of changing environmental factors. They survive and develop at the temperatures of 5–17°C and in the salinity range of 32–18‰. Gastrulae and bipinnariae survive under higher temperature values and salinity from 32 to 20‰. The tolerance for decreased salinity during the process of fertilization and in the latest stage of development, the brachiolaria with the developing juvenile starfish, was confined to the salinity range of 32–22‰, which agrees with the tolerance of adult starfish Asterias amurensis. Thus, for normal development of the Amur starfish in the early stages, some particular conditions of temperature and salinity are required. This is, probably, due to adaptive capabilities of each developmental stage and the peculiarities of the ecological conditions at particular depths.     

Effects of temperature and salinity on the larvae of two species of rhizocephalan (Crustacea: Cirripedia)

Summary

Responses of larvae of two rhizocephalan species to changes in seawater temperature and salinity were studied under laboratory conditions. Peltogasterella gracilis parasitizes the hermit crab Pagurus pectinatus, which occurs at stable salinity and gradually changing temperature in summer. Sacculina polygenea is a parasite of the crab Hemigrapsus sanguineus, which lives in the intertidal zone in summer where salinity and temperature can fluctuate during the day. The development of both species is comprised of five naupliar stages and the cyprid stage, and it was considered successful if more than 50% of the nauplii attained the cyprid stage. P. gracilis nauplii successfully developed at 12–20°C and 30–34‰, but at 22°C successful development occurred in a narrower salinity range (32–34‰). All nauplii died both at 25°C and in 26‰. S. polygenea nauplii successfully reached the cyprid stage at higher temperatures (18–25°C) and a wider salinity range (18–34‰) than P. gracilis nauplii, but at 12°C and 16‰ larval development of S. polygenea was suppressed. Under favorable conditions, naupliar development lasted 3.5 days in P. gracilis and 2–3 days in S. polygenea. The cyprids of both rhizocephalan species demonstrated a greater resistance to temperature and salinity changes than nauplii. However, P. gracilis cyprids were active in a narrower salinity range (16–34‰), as compared to S. polygenea cyprids (8–34‰). Under favorable conditions the cyprids of both species survived for 6 to 10 days.     

Acetylcholinesterase activity of the polychaete Nereis diversicolor: effects of temperature and salinity

In order to estimate the potential use of the mean wholebody acetylcholinesterase (AChE) activity from the ragworm Nereis diversicolor for the biological assessment of pollution by anticholinesterase agents in estuarine areas, we measured the effects of the main abiotic factors (i.e. temperature and salinity) on AChE activity. We report here that AChE activity tends to decrease in individuals sampled in tanks at a salinity of 30‰ as temperature increases. No tendencies in the evolution of AChE activity were observed in individuals sampled in tanks at a salinity of 15‰. In contrast, salinity seems to have a greater effect on AChE activity than temperature. At a temperature of 12°C, a salinity of 30‰ provokes a significant transient increase of AChE 2 days after the beginning of the maintenance period compared with a salinity of 15‰. The effects are short-term stress effects. We noticed only a transient increase of AChE activity between 2 days for individuals maintained in tanks at temperature of 20°C and salinity of 15 and 30‰, respectively, and 8 days for individuals maintained in tanks at salinity of 30‰ and at a temperature of 12°C after the beginning of the maintenance period, confirming the more pronounced effect of salinity over temperature.     

The Influence of Salinity and Temperature on Seed Germination in Salicornia bigelovii

Seeds of Salicornia bigelovii were germinated at 4.4°C, 15.5°C, and 26.6°C in saline solution containing from 0% to 8.08% sea salt. At 4.4°C, germination was delayed until the 26th day, but the final germination per cent was high in all salinities. At 15.5°C, germination was delayed until the 19th day, and the germination per cent was higher in the higher salinities. At 26.6°C, the germination began within one day and the germination per cent was higher at the lower salinities. With the exception of 26.6°C data, the maximum germination occurred at a sea salt concentration at 4.04 % which is very close to the salinity of the sea.     

Respiratory and osmoregulatory responses of the hermit crab, Clibanarius vittatus (Bosc), to salinity changes

Intertidal hermit crabs were stepwise acclimated to 10, 20, and 30‰ salinity (S) and 21 ± 1 °C. Hemolymph osmolality, sodium, chloride, and magnesium were isosmotic (isoionic) to ambient sea water at 30‰ and hyperosmotic (hyperionic) at 20 and 10‰ S, while hemolymph potassium was significantly hyperionic in all acclimation salinities. Total body water did not differ significantly at any acclimation salinity. Oxygen uptake rates were higher in summer-than winter-adapted crabs. No salinity effect on oxygen consumption occurred in winter-adapted individuals. Summer-adapted, 30‰ acclimated crabs had a significantly lower oxygen consumption rate than those acclimated 10 and 20‰ S. Crabs exposed to 30 10 30‰ and 10 30 10‰ semidiurnal (12 h) and diurnal (24.8 h) fluctuating salinity regimes showed variable osmoregulatory and respiratory responses. Hemolymph osmolality followed the osmolality of the fluctuating ambient sea water in all cases, but was regulated hyperosmotically. Hemolymph sodium, chloride, and magnesium concentrations were similar to hemolymph osmolality changes. Sodium levels fluctuated the least. Hemolymph potassium was regulated hyperionically during all fluctuation patters, but corresponded to sea water potassium only under diurnal conditions. The osmoregulatory ability of Clibanarius vittatus (Bosc) resembles that reported for several euryhaline brachyuran species. The time course of normalized oxygen consumption rate changed inversely with salinity under semidiurnal and diurnal 10 30 10‰ S fluctuations. Patterns of 30 10 30‰ S cycles had no effect on oxygen consumption rate time course changes. The average hourly oxygen consumption rates during both semidiurnal fluctuations were significantly lower than respective control rates, but no statistical difference was observed under diurnal conditions.     

Environmental factors affecting hatching of rotifer (Brachionus plicatilis) resting eggs

Hatching experiments were carried out on a population of Brachionus plicatilis (Dor strain) resting eggs produced in batch laboratory cultures under controlled conditions and then stored for at least one month at 4 °C in the dark. Light was found to be obligatory for termination of dormancy. Over the temperature range of 10–30 °C (at 9.0‰ salinity), hatching was optimal (40–70%) at 10–15 °C and decreased linearly with the rise in incubation temperature. Resting eggs incubated over a salinity range of 9–40‰ (at 15 °C) showed optimal hatching at 16‰. Incubation of resting eggs in distilled water permitted normal embryonic development, but neonates died at eclosion. Presence of algae, Chlorella stigmatophora (0.5 × 10⁶ cell ml^?1), was found to aid hatching.     

Effects of light,temperature and salinity on the growth rate of harmful marine diatoms,Chaetoceros convolutus and C. concavicornis that kill netpen salmon

Chaetoceros convolutus and C. concavicornis have been implicated in the death of salmon in netpens in the Pacific Northwest by damaging the salmon's gills. To better understand how environmental factors affect the distribution of these two species, the interacting effects of light, temperature and salinity on growth rate were examined by growing these species under a range of temperatures (4–18 °C), light (10–175 μmol photon m⁻² s⁻¹) and salinities (10–30‰). For C. convolutus, the growth rate showed a hyperbolic relationship with irradiance at 8, 14 and 18 °C and light saturation occurred at 9, 14 and 20 μmol photon m^t s⁻¹ respectively. At 4 °C for C. convolutus and 8 °C for C. concavicornis, cells grew at μ_max, even at the lowest irradiances tested (10 μmol photon m⁻² s⁻¹). For C. convolutus, the amount of light required to saturate growth rate increased with temperature in an approximately linear fashion. The Q₁₀ was 1.88, calculated by averaging over both species. C. concavicornis was the more euryhaline species growing at salinities as low as 17.5‰, while C. convolutus grew only at 25‰ and above.     

Hydromineral regulation in the saline water corixid Trichocorixa reticulata (Hemiptera: Corixidae)

The aquatic corixid Trichocorixa reticulata (Guerin-Meneville) inhabits coastal marshes, brackish water ponds and salt ponds of high salinity, suggesting the presence of well developed mechanisms for hydromineral regulation.Groups of corixids acclimated in salinities ranging from fresh water to just above 300% sea water (100‰) were analyzed for total body water content, haemolymph ionic and osmotic levels, and haemolymph free amino acids.Results indicate an excellent ability to maintain haemolymph Na⁺, Cl^?, Mg²⁺ and K⁺ hyperosmotic to the medium at low salinities and hyposmotic at high salinities. Calcium appears to conform closely to changes in external medium, becoming hyposmotic at very high salinities (80‰).Total haemolymph osmotic pressure was well regulated, the freezing point depression varying from 0.75°C in distilled water to 1.15°C in salinities of 100‰. Total body water was maintained at approx. 75% of the total animal wet weight at all salinities tested.Free amino acids were maintained between 40–60 mM in all tests and did not appear to change with salinity.     

Growth, maturation and photosynthesis of the brackish water alga Rhizoclonium sp. (Cladophoraceae, Chlorophyta) in relation to salinity

The effects of salinity on growth, maturation and photosynthesis were examined in the filamentous alga Rhizoclonium sp. (Cladophoraceae, Chlorophyta) growing in a brackish water habitat in a canal draining into Tokyo Bay, Japan. In this habitat Rhizoclonium sp. was exposed to a wide salinity range, both daily, 5–23‰ during November 1996, and hourly, 6–24‰ during the spring tide day. From the results of culture experiments, growth and maturation of Rhizoclonium sp. occurred in the wide salinity range of 10–40‰ at 20 μmol photons m‐²s‐¹ at 20°C, but did not occur at salinity of 0‰. Light saturation on the photosynthesis‐irradiance curve at 20°C at 20‰ was reached at 100 μmol photons m‐²s‐¹, which is characteristic for shade‐adapted algae. On the photosynthesis‐salinity curve at 20°C at saturated irradiance (160 μmol photons m‐²s‐¹), the net photosynthetic rate increased with increasing salinity up to 30‰ but decreased at 40‰. On the photosynthesis–salinity curve at 20°C at 20 μmol photons m‐²s‐¹ (at near in situ irradiance), the photosynthetic rates were almost the same in the salinity range from 0 to 40‰. Therefore, this species is able to grow, reproduce and photosynthesize with a relative efficiency in a wide salinity range, which shows that it is well adapted to a brackish water environment.     

Kulturverfahren zur Bestimmung der Salz- und Über-flutungsverträglichkeit vonPuccinellia spp. (Gramineae)

In the ecology ofPuccinellia species (P. maritima, P. distans, P. retroflexa andP. limosa of the German flora described to date) two environmental factors seem to be very important: the salinity of the soil or of the tidal sea water and, especially in regard toP. maritima, the periodical inundation during the tidal cycle. The latter species forms an important community (Puccinellietum maritimae) a few decimetres above the middle tide level. The other species seem to be specialized to localities of higher levels. Some 450 natural localities covered withP. maritima on the western coasts of Schleswig-Holstein (W. Germany) have been analysed with respect to the type of plant community, dominance ofP. maritima, frequency of inundations, level above or below middle tide level, and soil factors (for instance: Cl-ion content, electrical conductivity, pH, clay content, etc.). Physiological experiments have been carried out in greenhouses, experimental grounds, and culture-rooms to test the effects onP. maritima (number 57 from the optimal level within the Puccinellietum maritimae of the banks of the River Eider) of soil composition, light intensity and daylength, temperature, inundation, etc.P. maritima grows with long creeping stolons at daylengths of 16 hrs and more; it forms a caespitose tufted plant at daylengths of 12 hrs and less (light intensity: 10,000 lux and more). Optimal growth occurs between 17° and 23° C and under conditions of artificial flooding up to soil surface twice a day (for about 10 minutes) by artificial sea water of 25 ‰ S. Two culture techniques have been developed for testing growth and survival after 8 weeks under greenhouse conditions (20° C or more; 10,000 lux or more; 15 hrs daylength or more, after comparable pre-cultivation over 8 weeks under 12 hrs day and artificial light conditions; sand + 3 % peat). The first technique has been used for testing salt tolerances between 0 and 60 ‰ S (artificial sea water), the second for testing inundation tolerances (0–2.5 hrs inundation twice a day; artificial sea water of 25 ‰ S). Considering different proveniences ofPuccinellia species on German coasts, it became clear thatPuccinellia exhibits broader ecological and morphological than taxonomical variabilities. WithinP. maritima, for example, several ecological types can be separated. This finding indicates the possibility of isolating different ecological types for specific localities in land reclamation areas.