Intertidal zone of Svalbard 3. Littoral of a subarctic, oceanic island: Bjornoya

Twenty-two stations in the intertidal and shallow sublittoral of Bjornoya (74 °N, 19 °E) were studied in August 1994 revealing a large and diverse standing crop of macro-algae (16 species) and littoral macrofauna (at least 17 species). In most places the biomass of littoral macroorganisms exceeded 100 g ww/m². In the shallow sublittoral, between 2 and 20 m, 45 animal taxa and 23 algae species were collected. Littoral coarse sand meiofauna was dominated by Turbellaria, while, on algae, Halacaridae and Harpacticoida predominated. Meiofauna densities ranged from 0 to 169 ind./10 cm² and biomass from 0 to 0.4 g dw/m². The abundance of littoral species and their zoogeographic origin resemble that of Spitsbergen more than that of the northern Scandinavian coast, although both are of equal distance from Bjornoya. The first record of the boreal bivalve Mytilus edulis from the island is presented. Another striking feature was the presence of the arctic amphipod Gammarus setosus and the absence of its boreal sibling species G.oceanicus. Received: 19 March 1996 / Accepted: 1 December 1996     

Intertidal zone of svalbard

Summary In summer 1985–1991, the intertidal zone of the Svalbard archipelago was sampled in 242 localities. Thirty seven laxa of macrofauna and 22 of macrophytes were considered as littoral zone inhabitants. Four major littoral assemblages are described: Fucus-Balanus, Gammarus, Onisimus and Oligochaeta communities. More than 80% of the investigated coast is occupied by the Oligochaeta assemblage with mean biomass values less than 1 kJ/m². The richest benthos was found at Fucus-Balanus sites (8% of the coast line) with biomass values exceeding 2000 kJ/m². The southern tip of Spitsbergen is part of a major zoogeographical border in the littoral fauna distribution. Subarctic species like barnacles, periwinkles and Gammarus oceanieus predominate on the western coast whereas, on the Arctic East coast barren beaches, G. setosus predomination was found.     

Intertidal meiofauna of a high-latitude glacial Arctic fjord (Kongsfjorden, Svalbard) with emphasis on the structure of free-living nematode communities

Meiofauna communities of four intertidal sites, two sheltered and two more exposed, in Kongsfjorden (Svalbard) were investigated in summer 2001 at two different tidal levels (i.e. the low-water line and close below the driftline, referred to as mid-water (MW) level). A total of seven meiofaunal higher taxa were recorded with nematodes, oligochaetes and turbellarians being numerically dominant. Mean total meiofaunal densities ranged between 50 ind. 10 cm⁻² and 903 ind. 10 cm⁻². Our data showed a clear decrease in total meiofaunal densities with increasing coarseness of the sediment. Total meiofaunal biomass varied from 0.2 g dwt m⁻² to 2 g dwt m⁻² and, in general, was high even at low meiofaunal densities, i.e. larger interstitial spaces in coarser sediments supported larger meiofauna, especially turbellarians. The results on the vertical distribution of meiofauna contrasted sharply with typical meiobenthic depth profiles on other beaches, probably in response to ice-scouring and concomitant salinity fluctuations. Oligochaetes were the most abundant taxon, with a peak density of 641 ind. 10 cm⁻² at Breoyane Island. They were mainly comprised of juvenile Enchytraeidae, which prohibited identification to species/genus level. Nematode densities ranged between 4 ind. 10 cm⁻² and 327 ind. 10 cm⁻². Nematodes were identified up to genus level and assigned to trophic guilds. In total, 28 nematode genera were identified. Oncholaimus and Theristus were the most abundant genera. The composition of the nematode community and a dominance of predators and deposit feeders were in agreement with results from other arctic and temperate beaches. Nematode genus diversity was higher at the more sheltered beaches than at the more exposed ones. Low-water level stations also tended to harbour a more diverse nematode communities than stations at the MW level. Differences in nematode community structure between low- and MW stations of single beaches were more pronounced than community differences between different beaches and were mainly related to resources quality and availability.     

南麂列岛潮间带大型底栖动物群落优势种生态位

为了解南麂列岛潮间带大型底栖动物的群落特征及其物种间相互作用情况,于2012年5月至2013年2月对南麂列岛保护区内的12个资源位点(潮间带3个潮区的4个季节采样)进行了调查。共采集和鉴定出大型底栖动物354种,其中,18个优势种分别隶属于3门5纲12科。通过对优势种生态位的宽度、重叠度和相似比例的分析,发现:1)带偏顶蛤Modiolus comptus、条纹隔贻贝Septifer virgatus和异须沙蚕Nereis heterocirrata的生态位宽度较宽,均大于0.9;白条地藤壶Euraphia withersi和白脊藤壶Fistulobalanus albicostatus的生态位宽度则较窄,均小于0.5。2)各优势种群的生态位重叠度较低而生态位相似比例较高,生态位宽度值较高的物种对其他物种的生态位重叠值和生态位相似比例也较高,反之则较低。3)Bray-Curtis相似性聚类分析和非度量多维尺度排序(NMDS)结果表明,这些优势种基本属于同一生态类群,没有表现出明显的群落差异。经分析,潮间带大型底栖动物各优势种生态位宽度的分化是由于其对环境的适应能力和迁移能力的不同所导致的,而生态位重叠度较低情况的出现主要是由于各物种占据潮间带上不同的潮区,减小了种间竞争的压力。     

Acclimation of Intertidal Crabs

SVXOPSIS. Intertidal crabs are subjected to marked fluctuationsin environmental factors. Temperature and salinity influencethe distribution of organisms both on a latitudinal basis andalong a subtidal to terrestrial gradient. These factors areoperative on all stages of the life history. Resistance-adaptations. Adult fiddler crabs (genus Uca) fromthe temperate zone are more resistant to low temperature thantropical species. Also, the tolerance to low temperature ofcrabs from the temperate zone is greatly influenced by thermalacclimation, i.e. cold-acclimated crabs are more resistant thanwarm-acclimated animals. In contrast, tropical species havelimited adaptive ability. At elevated temperatures no consistentdifference in the lethal limits of crabs from tropical and temperatezones is observed. In contrast with the adults, larvae of tropicalspecies are cold-resistant. However, the larvae of all speciestested are more sensitive to reduced salinities than are theadults. Capacity-adaptatioyis. Subtidal species of crabs tend to havea lower level of respiratory performance, as measured by variousindices, than crabs from the intertidal zone. The metabolicresponse of fiddler crabs from the temperate zone is more labileat low temperature than in species from the tropical zone. Atelevated temperature the reverse response is observed. On aninterspecific basis, differences in the metabolictemperaturepatterns of acclimation of latitudinally separated populationsof U. pugilator are observed when based on the hypotheticalschemes of Bullock, Precht, and Prosser.     

Linking Intertidal and Subtidal Food Webs: Consumer-Mediated Transport of Intertidal Benthic Microalgal Carbon

We examined stable carbon and nitrogen isotope ratios for a large variety of consumers in intertidal and subtidal habitats, and their potential primary food sources [i.e., microphytobenthos (MPB), phytoplankton, and Phragmites australis] in a coastal bay system, Yeoja Bay of Korea, to test the hypothesis that the transfer of intertidal MPB-derived organic carbon to the subtidal food web can be mediated by motile consumers. Compared to a narrow δ¹³C range (−18 to −16‰) of offshore consumers, a broad δ¹³C range (−18 to −12‰) of both intertidal and subtidal consumers indicated that ¹³C-enriched sources of organic matter are an important trophic source to coastal consumers. In the intertidal areas, δ¹³C of most consumers overlapped with or was ¹³C-enriched relative to MPB. Despite the scarcity of MPB in the subtidal, highly motile consumers in subtidal habitat had nearly identical δ¹³C range with many intertidal foragers (including crustaceans and fish), overlapping with the range of MPB. In contrast, δ¹³C values of many sedentary benthic invertebrates in the subtidal areas were similar to those of offshore consumers and more ¹³C-depleted than motile foragers, indicating high dependence on phytoplankton-derived carbon. The isotopic mixing model calculation confirms that the majority of motile consumers and also some of subtidal sedentary ones depend on intertidal MPB for more than a half of their tissue carbon. Finally, although further quantitative estimates are needed, these results suggest that direct foraging by motile consumers on intertidal areas, and thereby biological transport of MPB-derived organic carbon to the subtidal areas, may provide important trophic connection between intertidal production and the nearshore shallow subtidal food webs.     

Mortality in Svalbard reindeer

Mortality rates in Svalbard reindeer followed the "U"-shaped pattern, with higher mortality rate among calves and old animals than in middle aged individuals. Assuming a stable population size, the mortality data predict a 16.2% annual mortality and recruitment rate among 6 months and older animals, and a male:female sex ratio of 48.5:51.5 among 1-yr old and older. Both predictions are supported by field data. Female mortality rate increased and differed from the male rate in the age interval 2-4 yr, while the male rate increased sharply and differed permanently from the female rate in the age interval above 6 yr. First and last breeding are thought to cause the increased mortality among 2–4 and 11–13 yr-old females. Increased involvement in rutting activities with age associated with lower grazing activity and depletion of fat reserves probably cause the increasing mortality rate among the 6+ yr males. Maximum life span was 17 yr in females and 12 yr in males. Apart from the unknown but possibly high neonatal calf-mortality, only few animals died during summer or during the rut in autumn. Death among calves, yearlings and most of the females occurred before antler-shedding in May-June. Most of the 2-yr and older males died after antler shedding, which occurs from December among the oldest and during April-May among the younger males. Hence, the major part of the mortality takes place in spring. The lack of visible subcutaneous and femur fat in most carcasses indicated starvation as the major mortality cause.     

Respiratory Adaptations in Intertidal Fish

SYNOPSIS: Intertidal rockpools provide a challenging environmentfor rockpool fish with rapid changes taking place in many environmentalparameters over a tidal cycle. Intertidal fish exhibit a numberof behavioural adaptations such as the avoidance of hypoxicsituations or remaining inactive during aerial "stranding."Other species are, however, well adapted to breathe air andexhibit morphological adaptations such as smaller gill areas,specialized buccopharyngeal epithelia and a proliferation ofcutaneous blood vessels in the skin. Oxygen consumption in rockpoolfish is comparable to non-intertidal fish and responds in asimilar manner to temperature changes. The ability to regulateoxygen consumption down to oxygen tensions below 40 Torr is,however, marked in rockpool species. Aerial and aquatic ratesof respiration are similar in those species which are able tobreathe air and the respiratory quotient normally remains between0.7 and 0.9. A number of intertidal fish are well adapted forcutaneous respiration, satisfying over half of their oxygenand carbon dioxide exchange through the skin. Ventilatory responsesto increased temperature, hyperoxia and hypoxia are similarto those of other fish but cardiac responses may differ in thatno change in heart rate is seen under hypoxia or hyperoxia.Ventilatory and cardiac responses to aerial respiration arewell adapted in some species maintaining ventilation and perfusionduring aerial exposure. A marked Bohr effect, low temperaturesensitivity and a temperature dependent Haldane effect havebeen measured in the haemoglobolin of some intertidal fish.These properties may assist oxygen transport and carbon dioxideexchange during cyclical changes in environmental parameterswithin an intertidal rockpool.     

Behavioral Adaptations of Intertidal Hermit Grabs

SYNOPSIS. AS an ecotone, the littoral environment is often complexand is generally rich in numbers and species of organisms. Thedisadvantages of the biotope in terms of exposure to physicalfactors of both the marine and terrestrial environments arepatent, but the advantages are not so evident. The continualreplenishment of food brought from the sea, particularly fordetritus-feeding animals such as hermit crabs, coupled withthe possibility and ability to establish microhabitatswith microclimaticconditions may constitute the principal advantage. Escape fromspecialized predators may also be important. Hermit crabs havesuccessfully exploited most intertidal environments. As membersof the "benthic detritus-feeding guild" food is abundant, andby utilizing their shells in conjunction with movements withinthe littoral zone they have met successfully most of the rigorsof the environment. The shell also provides some protectionfrom predation, particularly from non-specialized predators.Indeed,the behavioral patterns associated with living in shells whichpermit the shell to serve as a microhabitat constitute the majoradaptation enabling the hermit crabs to exploit the intertidalenvironment so successfully.     

Rapid Assessment of Intertidal Wetland Sediments

Urbanization of coastal areas poses a severe threat to ecologically valuable intertidal wetlands. This paper presents a pragmatic approach called Rapid Assessment for Intertidal Wetland Sediments (RAITWS) for evaluating the sediment quality of intertidal wetlands. RAITWS involves construction of reference groups, selection of a subset of environmental variables, matching of test sites to reference groups, prediction of the benthic fauna community structure (e.g. of macroinvertebrates) at test sites, evaluation of the Observation to Expectation ratio (O/E ratio), quantification of environmental variables with series of dynamic numerical models, and interpretation of the O/E findings. The proposed method extends the existing rapid biological assessment approach from static to dynamic applications. In particular, RAITWS provides a fast method of assessing intertidal wetland sites which are undergoing ecological change due to nearby coastal development.     

Salinity--stress and Desiccation in Intertidal Worms

SYNOPSIS. Intertidal worms (oligochaetes, polychaetes, sipunculids)inhabiting beaches and tidal fiats both on the open sea coastand in estuaries may be exposed to significant tidal as wellas seasonal variations in salinity. However, there are veryfew measurements of the actual variations in salinity encounteredby worms in nature. Behavior (irrigation of burrow, verticalmovements in burrows, migration in gradients of salinity)maybe important in determining to which of the available salinitiesin a tidal cycle the worms may be exposed. In response to rapidlowering of salinity, worms gain water and lose salts, theseprocesses combining in diluting the internal fluids. Internalilution occurs more slowly in euryhaline species than in stenohalinespecies. Worms fully adapted to salinities lower than 30 % seawater may be hyperosmotic (demonstrated for six species of Nereidae).Mechanisms involved in hyperosmotic regulation include activetransport of salts(demonstrated in Nereis diversicolor), reductionofthe permeability of the body surface to salts and perhapsto water, and perhaps production of hypo—osmotic urine.Sipunculids can tolerate considerable loss of water rom dehydrationand concomitant increases in osmotic concentration of the bodyfluids. It is suggested that worms exposed to significant tidalvariations in salinity may seldom be in osmotic equilibriumwith their external medium.     

Intertidal seawalls as habitats for molluscs

Coastal urbanization changes intertidal shorelines, by alterationand destruction of natural habitat and addition of new builthabitat. In Sydney Harbour, New South Wales, Australia, up to50% of the shoreline is composed of constructed habitat, particularlyseawalls. Research has shown that many components of intertidalassemblages live on seawalls, but patterns of abundance anddiversity are very variable. Seawalls differ physically fromnatural shores in a number of ways that are likely to influencedistribution and abundances of intertidal molluscs, which arevery important determinants of structure of intertidal assemblages. This study examined diversity, abundances and frequencies ofoccurrence of intertidal molluscs on seawalls and on naturalhorizontal and vertical shores in numerous locations in SydneyHarbour and in natural boulder-fields and artificial boulder-fieldscreated from rubble of seawalls. On seawalls, assemblages variedbetween tidal heights and among locations, but when data werecombined across locations, there were some general patterns.Sessile bivalves (oysters and mussels) and many limpets werefound in similar numbers on both habitats, or patterns variedinconsistently. Many coiled snails, in contrast, including whelksand grazing gastropods, plus opisthobranchs, which were eithercommon or relatively sparse on horizontal shores, were not foundon seawalls and found in intermediate frequencies on verticalshores. Similarly, common species of molluscs were found innatural and artificial boulder-fields in similar numbers, orpatterns were not consistent, although rarer species were notfound in these boulder-fields. Because molluscs are such importantcontributors to intertidal dynamics, these results have importantimplications for management of intertidal biodiversity in urbanizedand altered environments. (Received 18 July 2005; accepted 9 November 2005)     

Factors Affecting the Respiration of Intertidal Invertebrates

The nature and rate of gas exchange in intertidal organismsis variable and is the product of an extremely complex environmentalsituation. Such influences may be grouped into tidal-dependentfactors such as the proportion of time spent exposed to air,the magnitude of environmental temperature fluctuations, andthe availability of food. Factors which may be regarded as generallyoperating independently of tidal level include latitudinal variationsin environmental temperature. Superimposed upon such spatialenvironmental variations are seasonal factors such as temperatureand photoperiod, which impose a temporal cycle upon the metabolicrate. Finally, there are numerous endogenous factors such asbody size, activity level, and stage of development which profoundlyinfluence the rate of respiration. It can be shown that somefactors, such as aerial or aquatic conditions, may affect respirationqualitatively. Under aquatic conditions gas exchange is withthe surrounding sea water, but with increasing exposure to airintertidal invertebrates are able to respire aerially and towithstand the water loss associated with this process. Manyare also able to respire anaerobically under conditions of stress.In contrast, factors such as activity level, body size, nutritionalconditions, and exposure temperature affect respiration quantitativelyand are often interdependent. The metabolism of intertidal animalsis then endowed with considerable flexibility between the extremesset by the active and standard rates of respiration. This activerate of respiration is markedly temperature-dependent in mostinstances, whereas the standard rate, which is characteristicof quiescent animals, is not only lower but often has a lowtemperature coefficient. A reduction in respiration conservesmetabolic reserves during periods of stress, and the low temperaturecoefficient further minimizes depletion of such reserves despitethe high environmental temperatures which often prevail duringthe intertidal period.     

A Suite of Adaptations for Intertidal Spawning

Salt marshes and similar tide-dominated habitats present anunusual challenge for reproduction of resident aquatic organisms.Strong currents, siltation and hypoxia can potentially contributeto reproductive failure through mortality of the eggs or flushingof the eggs and larvae from the habitat. Fundulus heteroclitus,a small brackish water killifish, is a common resident of tidalmarshes along the east coast of North America from Newfoundlandto Florida. The reproductive strategy of this and related speciesis based on aerial incubation of eggs in the high intertidalzone. The eggs are resistant to desiccation and, when fullydeveloped, hatch on immersion. Copulatory behavior and anatomyof accessory reproductive structures are adapted to placementof eggs in protected incubation sites. The gonads of both malesand females mature rhythmically with an endogenous circasemilunarperiod, which is synchronized with the "spring" tides of newand full moons. Spawning occurs on high tides. Embryos developin 9–15 days, and usually hatch on the succeeding springtide series. Reproductive cyclicity in F. heteroclitus and relatedfishes ensures that spawning fish will have access to the highintertidal zone, thereby permitting aerial incubation of eggs.     

Predation of Svalbard reindeer by polar bears

Polar bears (Ursus maritimus) are believed to be obligate predators on marine mammals, and particularly, on two species of seals. This paper reports on observations of polar bears preying (n=7) and scavenging (n=6) on Svalbard reindeer (Rangifer tarandus platyrhyncus). Similar to their closest evolutionary ancestor, the brown bear (U. arctos), polar bears are opportunistic and will prey on ungulates. Reindeer are likely of minor importance to the foraging ecology of polar bears in Svalbard, but the observations suggest behavioural plasticity in response to a novel prey item. Accepted: 26 March 2000     

Why don't Svalbard reindeer migrate?

Reindeer and caribou are best known as migratory, seasonally nomadic animals; many continental populations, for example, travel between distinct summer and winter ranges which may lie hundreds of km apart. Much less is known about the movements of animals belonging to island populations. This paper describes seasonal and annual movements of wild reindeer Rangifer tarandus platyrhynchus on the high arctic archipelago of Svalbard, based on observations of nine animals captured and individually marked in Adventdalen, Spitsbergen, between 1977 and 1982. Four ear-tagged reindeer (one male and three females) were followed extensively for between four and seven years. Five radio-collared females were followed intensively for seven months in 1982. Svalbard reindeer seem neither to undertake long migrations nor to be nomadic within seasons like mountain reindeer or barren-ground caribou. They appear instead to use small, traditional, seasonal home ranges more, for example, like red deer or wild sheep. This atypical behaviour is discussed in relation to the dispersion of reindeers' resources in Svalbard.     

Bird feather fungi from Svalbard Arctic

Despite feather fungi being an important component of the Arctic fungal flora, their ecological role and diversity are not fully known. In the current study, fungal cultures were isolated from feathers (barnacle goose, common eider, and glaucous gull) collected in the Ny-Ålesund region, Svalbard. Isolates were identified by ITS region sequences, which include the ITS1, ITS2, and 5.8S rRNA. The result showed culturable yeast and filamentous fungi belonging to three classes: Ascomycota (Pyrenochaetopsis pratorum, Cladosporium herbarum, Thelebolus microsporus, Aspergillus versicolor, Penicillium commune, and Venturia sp.), Basidiomycota (Mrakia blollopis and Rhodotorula mucilaginosa), and Zygomycota (Mucor flavus). Most of the fungal isolates appeared to be cold-tolerant, and about 60 % of the isolates showed keratinase activity. The reasonably low fungal diversity colonizing feathers indicates that the birds of Svalbard are casual carriers of fungi which may result in a negligible impact on their health. To the best of our knowledge, this is the first record of fungal communities present on the feathers of birds in the high Arctic.     

Intertidal ecosystems of the seas of the USSR

Composition and distribution of intertidal ecosystem of rocky and unconsolidated facies were quantitatively studied from 1951 to 1975 in about 40 regions of the White, Barents, Bering, Okchotsk and Japan Seas. According to the degree of similarity (or to the degree of relationship), the investigated intertidal communities can be divided into the following 4 groups: (1) Uniform communities with identical forms as dominant species. A series of uniform communities constitutes a single association. (2) Parallel or vicarious communities with closely related vicarious forms as dominant species. A series of parallel communities constitutes a single formation. (3) Convergent or isomorphic communities with dominant species of the same, although not closely related life forms. A series of convergent communities constitutes a single formation type, or biome. (4) Anisomorphic, yet functionally analogous communities. Parallel communities ofFucus disticbus (northern Atlantic Ocean) andF. evanescens (northern Pacific Ocean), and uniform communities ofF. evanescens from various biogeographic provinces (southern Kuriles and eastern Kamchatka) are used for demonstrating the structure of intertidal biocenoses. In parallel communities, vicarious species are shown to dominate in number of species and, especially, in biomass. In uniform communities, common species are found to be leading forms.