Dynamics and biological cycle of a Melinna palmata (Ampharetidae) population during the recolonisation of a dredged area in the vicinity of the harbour of Brest (France)

The reproductive cycle and growth parameters were studied in a Melinna palmata population, for 3 yr after dredging, in the vicinity of the harbour of Brest, France. This species first settled in May 1979, 8 mo after dredging had ceased. Measurements of the diameter of coelomic oocytes indicated that spawning took place from August to October and settlement in autumn and early winter. The first settled cohort displayed a high growth rate (0.25 mm width mo^-1 in summer) and a low longevity (22 mo); the growth rate of the second settled cohort was not significantly different from the first, but its longevity was higher (28 mo); the third settled cohort had a lower growth rate (0.15 mm width per month), but lower mortality and therefore a longer life expectancy. A fourth cohort appeared in August 1981 but was not followed because of the termination of the study. M. palmata colonised the dredged area in two ways: by settlement of juveniles in autumn and by probable immigration of young and adults in May. The population increased in number and biomass from the end of dredging (August, 1978) to June 1981 and decreased after this period. The demographic strategy of this species changed from r- to K-selection during this recolonization as a result of intraspecific and interspecific competition.     

Reproductive biology of the lanternfish Benthosema pterotum from the Indian Ocean

Samples of Benthosema pterotum (Alcock) were obtained from the Arabian Sea (1976, 1979, 1981, 1983, 1984), off Mozambique (1978) and from the Bay of Bengal (1979). The sexual maturity stages are described. For females, the size of the largest oocytes was found to be most useful for size of the largest oocytes was found to be most useful for assessing maturity. Mature and spawning fish were found in all seasons. Samples from November 1983 differed from all others in having very few mature females. A few apparently spent fish were observed in July to August 1979 and November 1983. Some females mature at 25 mm and males at 20 mm, whereas others can still be immature at 45 and 40 mm, respectively. Of the total number of stations, four had significantly more males than females, twelve significantly more females, and forty-seven displayed no difference in the sex ratios. The vertical migration of the mature and spawning fish did not differ significantly from that of other individuals. Batch fecundity ranged from ca. 200 to 3 000 eggs fish ranging from 27 to 52 mm, relative fecundity from ca. 2 000 to 7 000 eggs g^-1 maternal dry weight. There are indications that B. pterotum spawns only once, but no firm conclusions could be drawn.     

Reproduction in Amphiura filiformis (Echinodermata: Ophiuroidea): Seasonality in gonad development

The burrowing ophiuroid Amphiura filiformis (O. F. Müller) (Echinodermata: Ophiuroidea) colonises an extensive area and is a numerically dominant member of the macrofauna in Galway Bay on the west coast of Ireland. There, it has a discrete, relatively short annual breeding period, from June to September, with peak activity in the month of August. The breeding period approximates in timing those of other European populations. The oocytes of a particular year are laid down in the autumn of the previous year; they begin to develop in spring, with the period of fastest growth in May/June. Gonad growth corresponds quite closely to the annual rise in water temperature, with spawning taking place during the warmest months of the year. The species is polytelic, and it is suggested that the long-lived Galway Bay individuals may breed every year for several years. The relationship between spawning and population dynamics is discussed in the light of current, available literature concerning A. filiformis from other parts of Europe. The role of so-called ultimate factors in the process of ophiuroid maturation and spawning is discussed.     

Population dynamics and secondary production in Melinna palmata (Polychaeta: Ampharetidae)

A Southampton Water (England) population of Melinna palmata Malmgren was studied from July 1978 to March 1980. M. palmata is a gregarious sedentary polychaete living in muddy substratum. The distribution of the polychaete in Southampton Water was related to the silt content of the sediment. The species occurs in sediments of <60% silt, it is dioecious, and the gametes are shed during a prolonged breeding season throughout the year, with peaks in March and July. Mature oocytes measure between 180 and 240 m in diameter at spawning, and fertilization is external. Unshed oocytes are resorbed. Annual secondary ary production was 0.42 gC m^–2yr^–1 and the P:B ratio was 2.19.     

Reproductive cycle,development and recruitment of two geographically separated populations of the dendrochirote holothurian Aslia lefevrei

The boreo-mediterranean holothurian Aslia lefevrei (Barrois) occupies cryptic habitats from low-water mark to ca. 20 m. During the present work specimens were collected from the west coast of Ireland (February 1979 to August 1980), where A. lefevreiis a prominent element in two discrete epibenthic assemblages, and from the north-west of Spain (September 1981 to August 1982), where this holothurian is densely aggregated in association with raft cultivation of the mussel Mytilus edulis. Its reproductive cycle, spawning process, embryological development, settlement, and early growth rates have been documented by means of laboratory and field studies. Depending on geographic location, spawning in the wild occurs between January and May. Development to the gastrula takes some 3 to 4 d. Uniformly ciliated dipleurula/auricularia hatch 12 to 24 h after gastrulation. The pentactula stage is attained approximately 7 d after fertilization, following which the larva settles. Newly settled individuals utilize the five primary tentacles for both feeding and locomotion. With the advent of small numbers of podia in the ambulacral regions, two of the primary tentacles prolong their locomotory and anchorage capabilities while the remaining tentacles develop adult characteristics and function solely in feeding. Growth was followed for an estimated 30 mo period using length-frequency analyses. In the first year of life, A. lefevrei attain an average length of 3.4 cm; individuals on the sea floor can attain up to 18 cm, indicating a possible life expectancy of 10 yr or more.Contribution No. 301 from the School of Marine Sciences, University College Galway, Ireland     

Population dynamics and reproductive cycle of Pholoë minuta (Polychaeta: Sigalionidae) in Galway Bay

Pholoë minuta (Fabricius) is a prominent member of the Amphiura filiformis (O.F. Müller) subcommunity in Galway Bay, Ireland. The aim of the present investigation was to study the population dynamics and reproductive cycle of P. minuta in this area. Monthly sampling over a 2 yr period (November 1978–October 1980), at a permanent station (18 m) with a fine sand substrate, revealed a mean density of 96 individuals per 0.1 m². The width of the fifth elytron was correlated with total body length and was used as a basis for analysing population structure. Four distinct year classes were evident and estimates of recruitment levels and growth rates were calculated. P. minuta is polytelic and reproduces for the first time when approaching 3 yr of age. Spawning occurred in March—April and appeared to be associated with a seasonal low in bottom-water temperature.     

Growth,mortality and recruitment of the yellow clam Mesodesma mactroides on Uruguayan beaches

We studied some aspects of the population dynamics of the yellow clam Mesodesma mactroides (Deshayes, 1854) which inhabits the eastern sandy beaches of Uruguay. Observations were made from March 1983 through March 1985 (harvesting season), and additional data from January 1988 to December 1989 (closed season) were also included in the analyses. Parameters of growth and mortality were estimated by methods that make use of age or length information. An age/length relationship was constructed by counting growth rings. Results were consistent with those obtained with modal class progression analysis and other length/frequency methods. The growth curve obtained from the age/length relationship did not account for seasonality in growth rate, and a seasonal growth model explained growth oscillations in a better way. The instantaneous coefficient of natural mortality (M) estimated for the closed season was 1.64, whereas an increase in fishing mortality (F) was observed during 1984. Age composition did not change during the 2 yr of study, and the first 6 mm class accounted for over 50% of the population. The main contribution of recruits was observed between late summer and early fall (February to April), and the recruitment pattern suggested one main settlement period per year. Growth and recruitment success appeared to be regulated by density-dependence processes. Some implications for management are considered in this context. Methodological aspects concerning the reliability of empirical equations and programs for estimating growth and mortality are discussed.     

Effects of the 1983-El Niño on growth and carbon and nitrogen metabolism ofPleurophycus gardneri (Phaeopyceae: Laminariales) in the northeastern Pacific

Growth and compounds of carbon and nitrogen of the northeast Pacific kelpPleurophycus gardneri (Laminariales, Laminariaceae) were assessed before, during and after the 1983-El Niño Souther Oscillation event. This 2-yr study provides evidence that reduced ambient levels of nitrate and phosphate from March until August/September, 1983, in combination with elevated seawater temperature, caused a significant impairment of growth. Blade surface area, blade length, total fresh weight, and dry weight on an areal basis were significantly reduced in 1983 compared to 1982 (P<0.01). They were also significantly smaller in 1984 than in 1983 (P<0.05). The C:N values obtained both in May and July 1983 were considerably higher than in 1982, while those in May 1984 were strikingly smaller than in both 1982 and 1983. Mannitol content of the mibrid in May 1983, exhibited the highest levels recorded during the 2-yr study period, with ca. 19% dry weight and significantly exceeded mannitol content measured in May 1982 (average: 13%) and in May 1984 (average: 8%). The concentration factor for internal vs external nitrate in the midrib was 700 x ambient in May 1982 and 1984 compared with 20 x in May 1983. Ninhydrin positive substances (NPS) averaged 117 mol g dry wt^-1 in May 1984 compared with ca. 50 mol in May 1982 and 1983. The pigment ratios chlorophyllc: chlorophylla and fucoxanthin: chlorophylla in May 1983 were similar to those obtained in 1982, but were significantly different in May 1984. It is suggested that the interactive effects of temperature stress and nutrient limitation in 1983 caused a disruptive influence on C- and N-metabolism ofPleurophycus gardneri, which still affected growth performance in 1984.     

Effects of salinity and adult extract on settlement of the oligohaline barnacle Balanus subalbidus

Balanus subalbidus (Henry) has the most oligohaline distribution of three congeneric barnacles in Chesapeake Bay and tolerates prolonged exposure to fresh water. We studied larval settlement (i.e., permanent attachment and metamorphosis) of B. subaldius in the laboratory, over a 3 yr period, May 1989 to March 1992, under the following conditions: (1) across an array of salinities at 25°C in the presence and absence of settlement factor consisting of adult B. subalbidus extract; (2) in the presence of conspecific or congeneric settlement factors; and (3) cyprids which were, and were not, induced to delay metamorphosis were compared in their capacities to settle in a range of salinities. Discrepancies between salinity profiles of larval settlement in the laboratory and adult oligohaline distribution in the estuary were striking, and there was a significant interaction between salinity and settlement factor. Averaging results of four different batches of larvae, although peak settlement (87±9%) of B. subalbidus occurred at 2 ppt salinity in the presence of adult cue, substantial settlement also occurred at higher salinities: >70% at 5, 10 and 15 ppt; and 47% at 20 and 25 ppt. In addition, settlement in the absence of settlement factor was relatively high (>50%) and peaked at mid-salinity ranges (e.g. 56±10% at 15 ppt). Variation observed in settlement among larval batches reflected detailed differences in settlement between adjacent test salinities. No difference in settlement occurred between replicate aliquots of cyprids within a batch. Cyprids of B. subalbidus settled most abundantly in the presence of settlement factor extracted from conspecifics, followed in decreasing order by settlement factor extracted from B. improvisus and B. eburneus. Delay of metamorphosis produced by keeping B. subalbidus cyprids for 8 d at 5°C resulted in a decreased level of settlement, but settlement frequency patterns of delayed and non-delayed cyprids were indistinguishable relative to salinity. These results indicate that the oligohaline distribution of adult B. subalbidus is probably not determined by larval behavior at settlement. We suggest that pre-settlement behavior, resulting in larval retention in low saline waters, could be an important factor in determining distribution of this species.     

Demography of Pholoe minuta (Polychaeta: Sigalionidae) in Galway Bay,west coast of Ireland,with special reference to settlement and recruitment patterns

Pholoe minuta is a numerically dominant member of the Amphiura filiformis subcommunity in Galway Bay. A longterm (5 yr) assessment of its population structure highlighted the shortfall in information regarding juvenile stages in the post-spawning months. Additional remote and in situ sampling programmes (including the use of a Muus sampling device), covering two successive postspawning periods, were undertaken to provide information on the juvenile recruits. Estimates of density levels (130 to 680 m^-2), growth rates (doubling in size in 2 mo) and mortalities (80%) were calculated for the newly settled P. minuta. Mean monthly densities, seasonal population structure, recruitment levels (21.1%), growth (1 mm per annum) and survivorship patterns of the adult population were evaluated using the dorsal width of the fifth chaetiger, which is shown to be a suitable parameter of total body size. The success of grab sampling as a method for examining early settlement of P. minuta is critically reviewed, and a recommendation for future benthic population studies is proposed.     

The reproductive biology of Nautilus pompilius in the Philippines

Records of Nautilus pompilius trapped in the Tañon Strait, Negros Oriental, Philippines were kept for a 1 year period from August 1971 through August 1972, and ovaries of mature females collected from August 1971 through March 1972. Females averaged only 8% of the catch during the year of study, but were more abundant in catches from January through May. The male:female ratio was not markedly altered at any depth in the trapping range (61 to 300 m). During the 8 month period, there was no trend apparent in the changes in average size of the ovaries collected; however, oocytes within varied markedly in their maximum weight. Encapsulated spermatophores are stored above the buccal cone on the male, and are attached unencapsulated below the ventral cirri of the female. N. pompilius pairs kept at 80 m remained healthy but laid no eggs from September 1971 through May 1972.     

Population dynamics and reproduction of Mysella bidentata (Bivalvia: Galeommatacea) in Galway Bay,Irish west coast

Mysella bidentata (Montagu) is found in high densities in an Amphiura filiformis (O. F. Müller) community in Inner Galway Bay, west coast of Ireland. As part of an ongoing investigation at one station within this community, the population dynamics and reproductive pattern of this bivalve were investigated during the period November 1978-December 1981. Monthly sampling over the 3 yr period revealed a mean population density of 745±672 individuals m^-2. Recruitment occurred during August-October and three year-classes were identified. Growth rates were assessed by analysis of length-frequency histograms and winter growth checks. Individuals from the Y1 and Y2 year-classes functioned as hermaphrodites during the 1980 and 1981 reproductive seasons. The Y0 year-class contained both males and hermaphrodites. Results are compared with available information on the same species from other locations.Contribution No. 225 from the School of Marine Sciences, University College, Galway Ireland     

Reproduction of the Antarctic fish Nototheniops nudifrons

The reproductive biology of the Antarctic fish Nototheniops nudifrons (Lönnberg, 1905) was analyzed by examination of the gonads of fish collected in March and April 1985 in trawls near Low Island, Antarctic Peninsula, and compared to direct observations of reproduction and early larval development in the laboratory from March to October of the same year. Males and females reached sexual maturity at an age of 4 to 5 yr. Mature males differed in coloration from females and immature males. Ovaries of sexually mature females contained two distinct size modes of vitellogenic oocytes, representing two separate clutches of developing eggs. Females spawned 100 to 3 500 demersal eggs, which were laid in a nest in crevices or under rocks, and guarded by the male for about 4 mo. Females did not assist in nest defense or egg care. Most spawning in the field and in the laboratory occurred in late fall and early winter (May to June). A second clutch may be spawned in spring (November and December). Eggs hatched after 124 d, and larvae were raised for 38 d. Otoliths of larvae contain internal microincrements, which are deposited in a daily fashion, and are visible by light microscopy. The otoliths of 32 adult fish were examined by scanning electron microscope, and counts of microincrements in these otoliths allowed the backcalculation of hatching dates. Estimated hatching dates were between September and May.     

Spread ofCyclope neritea (Mollusca: Gastropoda) along the north-eastern Atlantic coasts in relation to oyster culture and to climatic fluctuations

The geographic distribution ofCyclope neritea (Linné) (Mollusca: Gastropoda) along the Atlantic coasts of Portugal, Spain and France is reported. Analysis of information published over the last 90 yr indicates that, since 1983,C. neritea has extended its range northwards from Arcachon Bay along the coast of the Bay of Biscay. The spread of this small gastropod is directly related to the commercial transport of the Pacific cup oyster (Crassostrea gigas Thunberg) to the Atlantic from Mediterranean oyster-culture sites, and to its encountering climatic conditions suitable for its settlement and reproduction in its new habitat. Its transport by human intervention explains the rapid spread ofCyclope neritea during 1983 and 1984, despite its lack of a planktonic stage or of effective natural migration by adults. Climatic conditions in the southern parts of the Bay of Biscay are similar to those of the French Mediterranean lagoons, explaining the easy acclimatization of this eurythermic gastropod. Also, coastal air and sea-surface temperature records over the last two decades (1971–1988) have revealed a slight warming of the southern parts of the Bay of Biscay. This has resulted in a more strongly marked latitudinal thermal gradient along the Bay of Biscay and has furthered survival and reproduction ofCyclope neritea emigrants. A detailed analysis of commercial supplies of cup oysters to the Bay of Biscay from the Mediterranean coast indicates that theC. neritea emigrants undoubtedly originated from the salt-water lagoons of Salse-Leucate and Thau (French Mediterranean coast).     

Movements of lobsters (Homarus americanus) tagged in the Bay of Fundy,Canada

Of the 18 359 American lobsters (Homarus americanus) tagged and released at three locations in the Bay of Fundy during 1977–1980, 5 375 lobsters (29.3%) were recaptured within 6 yr of release. Mature lobsters (95-mm carapace length, CL) on average moved significantly greater distances than immature lobsters (<95-mm CL). Many (16.4%) of the mature lobsters were recaptured >92.6 km (50 nautical miles) from the release sites; the farthest distance moved was 798 km for a male at liberty for 3.5 yr. Examination of the direction of movements indicates some intermixing of lobsters within the Bay of Fundy, and throughout the Gulf of Maine and the adjoining Continental Shelf and slopes. Mature lobsters were recaptured in deeper waters during winter than during summer. The seasonal shallow-deep migration of mature lobsters in the Bay of Fundy is possibly associated with maximizing degree-days for molting, growth, gonadal development, and egg development. In some areas, mature females on average moved farther and seasonally earlier into deeper waters than mature males. Although the seasonal migration resulted in many lobsters returning to the original release area year after year, some lobsters made extensive long-distance movements away from the Bay of Fundy. Temperature-dependent, seasonal deep-shallow migration can explain both the local returns and the long distance migrations of mature lobsters in the Bay of Fundy and the Gulf of Maine. To achieve appropriate seasonal temperature regimes, mature lobsters have to move different distances and directions, depending on local topography.     

Field survey of the occurrence and significance of regeneration in Amphiura filiformis (Echinodermata: Ophiuroidea) from Galway Bay,west coast of Ireland

The Boreo-Mediterranean amphiurid Amphiura filiformis (O. F. Müller) occurs in high densities within Galway Bay. This burrowing species consistently shows signs of recent regeneration (of both arms and disc “cap”) at the above locality. Specimens were collected by SCUBA in March, April and May 1980, May 1981, and April 1982. Biomass assays have revealed that individuals with up to 50% (mean ca. 25%) of their entire body weight consisting of regenerated tissue are not uncommon. The occurrence of arm breakage and regrowth was found to be more frequent in the proximal (basal) and mid-arm regions than in the exposed arm tip portions. Roughly 3% of the population were found to be in the process of regenerating the disc “cap” or covering. Preliminary results from gut analyses of potential predators at the sampling station indicate that young flatfish (plaice and dab) actively “crop” the arms of A. filiformis. Records from north western Europe of this species occurring in the diets of fish and invertebrates are considered. In this long-lived species, the continual necessity to regenerate is deemed to be a major drain on bodily resources.     

The ichthyoneuston of Galway Bay (Ireland)

The ichthyofauna of the neustal (0 to 10 cm) and immediate subsurface water (12 to 48 cm) of Galway Bay was sampled during the day from June 1983 to September 1984 and at night from May to September 1984. Species diversity (H) and the number of species per sample were significantly higher at night. The density of larvae at night was higher only during May. Thirty-nine of the more common species were grouped by factor analysis resulting in 13 species groups with distinct spatial and temporal distributions. Three main time periods, February to April, May to July and July to September and three spatially defined station categories, each of which had distinct species groups, were also isolated by factor analysis. Station categories were contiguous and hydrographically and topographically distinct. Eight species groups showed evidence of vertical migration. Five groups were most abundant from July to September compared with three during May to June and one to two at other times. Eighty-one species or other taxomonic entity (genus or family) were recorded. The majority were pseudoneustonic and represented by early larvae and post-larvae. Euneustonic species (Ciliata mustela, Ciliata septentrionalis, Crenimugil labrosus, Gaidropsaurus mediterraneus, Gasterosteus aculeatus, Liza sp., Rhinonemus cimbrius, Scophthalmus maximus) were all present as late post-larvae or juveniles and all except Ciliata spp occurred during autumn. Facultatively neustonic species (Ammodytes marinus, Belone belone, Ctenolabrus rupestris, Entelurus aequoreus, Nerophis lumbriciformis, Sprattus sprattus, Trachinus vipera) were, except for Belone belone and Ctenolabrus rupestris, all represented by juveniles. All except Ammodytes marinus and Sprattus sprattus were common only in autumn.     

Reproduction of<Emphasis Type="Italic"> Ophiactis resiliens</Emphasis> (Echinodermata: Ophiuroidea) in New South Wales with observations on recruitment

Reproduction of the ophiuroid Ophiactis resiliens Lyman 1879, a common species in the shallow waters around Australia, was examined over 1 year in two populations near Sydney, New South Wales. Gametogenesis was documented by histological examination of the gonads. Vitellogenesis in females and spermatocyte proliferation in males started in February and March. O. resiliens had an annual spawning period from May to September/October with peak gamete release from May to July. Thereafter, spawning occurred in some specimens through November. Gravid gonads were present for approximately 2 months longer in O. resiliens from Clovelly Bay than in those from Little Bay. At both sites spawning was episodic and gametogenesis continued through most of the spawning season. Most specimens (50–100%) collected from November to March had indeterminate/recovery stage gonads, the sex of which, could not be determined. The timing of gametogenic renewal during these months varied among individuals. O. resiliens has a 3-month planktonic stage and the presence of juveniles, 0.5 –1.5 mm disk diameter, in the coralline algal turf at Little Bay from February to May, suggests that settlement occurs in summer and autumn at this site. In contrast, juveniles were rarely encountered in coralline turf at Clovelly.     

Long-term changes in populations of subtidal bivalves (Abra alba and A. prismatica) from the Bay of Morlaix (Western English Channel)

Two populations of Abra alba (Wood) and one of A. prismatica (Montagu) (Mollusca: Bivalvia) were studied over a 10 yr period (1977–1987) in two muddy fine-sand subtidal communities of the Bay of Morlaix, France. The survey provided an example of long-term changes in the three Abra spp. populations, which displayed synchronized changes, with a regular annual cycle and increasing densities during 1979–1980 related to the higher concentration of organic matter resulting from the Amoco Cadiz oil spill in March 1978. A. alba rapidly adapts its demographic strategy to eutrophic conditions by increasing its reproductive potential, growth, and abundance. During times of eutrophication, A. alba has three spawning periods and three recruitments per year as opposed to two spawning periods and two recruitments per year during oligotrophic conditions. Growth of the juveniles of this species is insignificant until spring for individuals recruited in the autumn, whereas individuals which settle during spring or summer display immediate rapid growth. A. prismatica has a low capacity to adapt to eutrophic conditions. It has one annual period of sexual maturation at the end of the summer, with spawning in September–October and settlement beginning in mid-November. Growth of the juveniles after settlement is also insignificant until April. These results enable comparison of the demographic strategies of these two sympatric species.     

Population ecology and secondary production of the polychaete Loimia medusa (Terebellidae)

In soft-sediment marine and estuarine habitats, population dynamics of resident species are an important aspect of commnity structure and function, yet the population dynamics of many members of these communities remain poorly studied. The population dynamics and secondary production of the infaunal terebellid polychaete Loimia medusa (Savigny) were investigated in a shallow sand habitat of the York River, Chesapeake Bay, Virginia, between June 1989 and December 1990. Monthly sampling throughout 1 yr revealed that individuals were present year-round with maximum densities of 60 ind m^-2 and a life span of 1 yr. Abundances were highest from August through September when two cohorts recruited to the population. Mean individual growth was highest in summer, and appeared to be a function of temperature rather than food limitation. Adults were reproductive from May through October and exhibited high fecundity; the number of oocytes segment^-1 ranged from 201 to 15840 among worms. Larvae initially appeared approximately 1 mo after gametes were first observed in adult L. medusa, and these larvae appeared to spend less than 1 mo in the plankton. Abundances of larvae in the water column were significantly higher around new moon, suggesting lunar spawning periodicity. New recruits attained sexual maturity within 2 mo of settlement. Secondary production was 3.3 g ash-free dry wt m^-2 yr^-1 and the P/B (production/biomass) ratio was 3.0. Despite equilibrium species characteristics such as large size, high fecundity, and planktonic larvae, L. medusa exhibits some characteristics typically ascribed to opportunistic species, namely, the capacity for rapid growth and maturation, a short life span and a relatively high P/B ratio. This mixture of life history characteristics emphasizes that there is no simple dichotomy between opportunistic and equilibrium species. We caution that the dominance of large infaunal polychaetes in soft-bottom estuarine and marine environments may not be a useful indicator of undisturbed habitats.