Larvae In Habitats Research Articles

Zooplankton community structure in the kelp beds of the sub-Antarctic Prince Edward Archipelago: are they a refuge for larval stages?

Kelp beds are thought to provide a refuge for a variety of marine organisms by damping waves, changing hydrodynamic flow, offering substrata for epiphytic species, and altering the abundances of predators and prey. At the sub-Antarctic Prince Edward Islands, a typical flow-through system, kelp beds have the potential of acting as a prime habitat for a variety of pelagic species that would otherwise be swept away and lost from the island ecosystem. The current study investigates the effects of kelp beds on the abundance and composition of zooplankton and microphytoplankton, with the main aim of determining whether kelp beds act as a repository for larval stages in general, and for the swimming prawn, Nauticaris marionis, in particular. Salinity gradients created by freshwater run-off indicated that kelp beds at Marion Island retain surface water and restrict water exchange with the open ocean. Both the abundance and diversity of zooplankton were greatest within the kelp beds. This was partially due to the high abundance of kelp-associated species, but also to the apparent retention of naupliar larvae within the kelp canopy. Unlike the larvae of ostracods and copepods, caridean zoeae were rare, indicating that kelp beds are not a prime habitat for larvae of N. marionis. The larval retention mechanism for this species, therefore, remains unknown. Apart from retaining water and certain species of zooplankton, chlorophyll a/phaeopigment ratios confirmed the existence of a substantial detrital pool within the kelp beds. This retention of detritus may explain the observed importance of kelp-derived matter in the diet of many nearshore animals. In contrast to the zooplankton, kelp beds seemed to have little effect on the abundance and composition of microphytoplankton, and chlorophyll a values were low at all stations.

Spatio-Temporal Distribution of Larval and Adult Tiger Beetles (Coleoptera: Cicindelidae) from Open Areas in Central Amazonian Floodplains (Brazil)

We investigated the regional occurrence and guild structure of tiger beetle species from open areas in Central Amazonian floodplains. Populations of larvae and adult beetles were observed during monthly field excursions from 1997–1999 to reveal life cycles, habitats, diel activity patterns, and other behavioral traits. One of the eight species found in open areas of Central Amazonia is represented by two subspecies. All except one species were found to reproduce in either white- or blackwater floodplains (6 and 4 species/subspecies, respectively). Habitats of larvae and adult beetles, diel activity patterns, as well as life cycles are given for all species. As a result of different life cycles (seasonal temporal segregation), diel activity patterns (diel temporal segregation), (micro-)habitats (spatial segregation), and behavior, intraspecific segregation of larvae and adult beetles was common. Its extent varied between species, ranging from almost complete segregation to partial overlap. Interspecific segregation was extensive. In larvae this was mainly due to different (micro-)habitat preferences (spatial separation). In adult beetles it was related to different life cycles, activity patterns and (micro-)habitats (seasonal, diel temporal, and spatial segregation). In addition, mandible gapes of adult beetles were different in species within guilds. Larvae of solely one or two pairs of species and adult beetles of only two pairs were found to live steadily together. Hence, guild structures showed strong niche separation. Possible implications for a better understanding of coexistence of tropical tiger beetles as well as for mechanisms mediating coexistence in general are discussed.

Spatial and Temporal Growth Rate Variation of Bay Anchovy (Anchoa mitchilli) Larvae in the mid Hudson River Estuary

Estuaries are critical habitats for larvae and juveniles of many marine fishes, possibly because they promote high growth rates and survival rates. We investigated spatial and temporal changes in growth rate of larval bay anchovy (Anchoa mitchilli), in the middle Hudson River estuary where abundance of larvae is high. In two consecutive summer seasons, we sampled larvae at 4 sites evenly spaced over 45 km, at weekly intervals for up to a month. We examined otoliths to determine age in days and then used age-length regressions to estimate growth rate. In 1995, larval anchovy growth rates varied from 0.39 to 0.88 mm d−1 (median=0.48 mm d−1). In 1996, growth rates varied from 0.41 to 0.77 mm d−1 (median=0.55 mm d−1). In both years, we found significant spatial and temporal variation in growth rate. Larvae collected in the upper portion of Haverstraw Bay tended to grow more slowly than larvae collected in other sites. The dates on which the most rapidly growing larvae were collected varied from site to site. Neither temperature nor salinity variations explained growth rate differences. Growth rate variation, probably governed by patches of zooplankton, occurred on temporal scales of a week and spatial scales of 15 km.

Phylogeny of the central-western Pacific subgenus Inseliellum (Diptera: Simuliidae)

Subgenus-level groups of western and central Pacific Simuliidae are briefly assessed using phylogenetic principles. Inseliellum and Nevermannia (ruficorne-group) are established as sister taxa. Detailed morphological analysis of 32 species of Inseliellum shows that the Micronesian Simulium trukense is the basal lineage. Austral and Cook islands species, plus those of the Marquesas Islands, form the next basal clade. Simulium malardei is the sister taxon of all other Society Islands species, including Simulium adamsoni from the Marquesas Islands. There are three clades: the tahitiense-group, which is weakly supported, the castaneum-group, which is moderately well supported, and the oviceps-group, which is strongly supported. One of two most parsimonious phylogenies that is in agreement with independent cytological information is presented. Habitat preference and larval behaviour are optimized on this phylogeny, providing information about evolutionary trends. Brief comments are made regarding geological development of the habitats of larvae of some species.

Forest Canopy Closure and Juvenile Emigration by Pool-Breeding Amphibians in Maine

For amphibians that breed in temporary pools, juvenile emigration is an important life-history movement linking the aquatic habitat of larvae to the surrounding upland habitats occupied by maturing animals and adults. However, little is known regarding the habitat preferences and sensitivity to disturbance of newly metamorphosed amphibians. We examined whether selection occurs for closed-canopy forest conditions during emigration by using pitfall traps and drift fences to sample naturally occurring populations of wood frogs (Rand sylvatica) and spotted salamanders (Ambystoma maculatum) along recently created forest-clearcut edges in central Maine. Habitat preferences during emigration were further investigated via an experimental approach that quantified movements of newly metamorphosed wood frogs cultured in artificial pools located along an abrupt forest-power line edge. Among natural populations, the abundance of juveniles and adults of both species declined sharply across a gradient running from relatively mature forest-interior habitat (70-90 yr old) to recently clearcut habitat (2-11 yr old). Similarly, in the power line experiment, juvenile wood frogs showed an emigration preference for closed-canopy habitat immediately upon metamorphosis, with the highest capture rates occurring in microhabitats characterized by dense foliage in both the understory and canopy layers. Our results suggest populations of wood frogs, spotted salamanders, and other amphibian species breeding in temporary pools are likely to benefit from efforts to maintain connectivity between upland forest habitats and aquatic breeding sites. Seminatural field experiments provide a valuable manipulative approach for studying the potential effects of habitat fragmentation on populations of migratory amphibians.

Anopheles albimanus (Diptera: Culicidae) and Cyanobacteria: An Example of Larval Habitat Selection

Northern Belize has extensive herbaceous wetlands. Those dominated by sparse emergent macrophytes, rushes (Eleocharis spp.) and sawgrass (Cladium jamaicense Crantz), often develop floating mats of cyanobacteria (blue-green algae). These mats provide suitable habitat for larvae of the malaria transmitting mosquito Anopheles albimanus Wiedemann. Presence/absence of A. albimanus larvae and cyanobacterial mats was assessed in marshes located throughout northern Belize. Of the 21 marshes examined during the 1993 wet and 1994 dry seasons, cyanobacterial mats were found in 11 and A. albimanus larvae were detected in 9 of these 11 marshes. No A. albimanus larvae were found in marshes without cyanobacterial mats. Mosquito larvae were collected along two 1,000 m long transects in both the wet season (August 1993) and the dry season (March 1994) to delineate larval distribution in marshes with cyanobacterial mats. A. albimanus larval densities in cyanobacterial mats were relatively high in both seasons: 2.8 and 2.3 larvae per dip in the wet and dry seasons, respectively, in Chan Chen marsh; and 0.8 and 1.02 larvae per dip in Buena Vista marsh. Numbers of larvae per dip did not significantly change with increasing distance from houses/pastures or margins of the marsh. A field experiment showed a strong preference of ovipositing A. albimanus for cyanobacterial mats. Higher temperatures and higher CO2 emissions from cyanobacterial mats are possible ovipositional cues.

Feeding preferences and their modification in early and late instar larvae of the bagworm,Thyridopteryx ephemeraeformis (Lepidoptera: Psychidae)

Feeding preferences in naive first instar and penultimate-final instar bagworm (Thyridopteryx ephemeraeformis)larvae were investigated using two choice tests. Naive first instar larvae showed a general (though not exclusive) preference for black willow (Salix nigra)over other hosts tested, regardless of the host of origin. Penultimate-final instar larvae showed strong preferences for the previous rearing host, suggesting induction of host preference; there was no evidence of host origin effects. The ability to discriminate among hosts is important if it is actually used to make host choices based on host quality. In bagworms, where host choices (if any) must be made by larvae in habitats where several hosts are often present, host discriminatory ability is likely important.

The Absence of Antipredator Behaviour in the Larvae of Leucorrhinia dubia (Odonata) and the Consequences for Their Distribution

Acidified bog ponds were the only previously reported habitat of larvae of the dragonfly Leucorrhinia dubia (Van der Lind.) (Odonata: Libellulidae). To study its present range of habitats, twenty lakes in southwestern Sweden were sampled. Ten of the lakes supported fish, the other ten lakes were fishless and acidified. L. dubia was found to occur in all ten fishless lakes but in none of the lakes which contained fish. To test the hypothesis that fish predation was the factor behind the distribution of L. dubia, a laboratory study was made where perch (Perca fluviatilis L.) was shown to discover and catch significantly more L. dubia than other dragonfly larvae from lakes with fish. When exposed to a simulated fish attack larvae of L. dubia tried to escape, whereas most larvae of two other genera from lakes with fish feigned death. This result, together with earlier studies on diel activity of L. dubia, supports my opinion that L. dubia is more susceptible to fish predation than are larvae of certain other genera from lakes with fish.

Bromeliáceas como espacio vital para larvas de Conocephalidae y Copiphoridae (Insecta, Saltatoria, Ensifera, Tettigonioidea)

The inner part of ground growing or epiphytic Bromeliads filled with water can be the habitat of larvae of Conocephalidae and Copiphoridae. These grasshoppers dive into the water when disturbed. This is enabled by the anatomy of the stigmata. From the waiting position half submerged they ambush for prey, organisms which may come from the upper part of the plant.

Mountain Mosquitoes of the Gothic, Colorado, Area

Mosquito species inhabiting a high mountain area (9000 to 12,000 feet) in south-central Colorado west of the Continental Divide comprised 11 Aedes, 4 Culiseta, 1 Culex, and 3 chaoborines. They can be placed by altitudinal associations in two major groups: 1) mountain species, subdivided into alpine (A. impiger) and subalpine (A. cataphylla, communis, hexodontus, implicatus, and pullatus; Culiseta incidens, impatiens, inornata; probably Aedes fitchii and Culiseta alaskaensis), and 2) valley and foothill species (Aedes cinereus, dorsalis, increpitus, spencerii idahoensis, and Culex tarsalis). Seasonal development, abundance, and species dominance, as shown by four seasons of collecting, are discussed and illustrated by charts; notes on habits of adults and habitats of larvae, with associated species and collection records, are given for each species, along with pertinent taxonomic observations. The origin of the faunal elements represented by the 28 species of the Colorado Rockies is discussed. One species of mosquito (Aedes trichurus Dyar), taken east of the study area, and one chaoborine (Eucorethra underwoodi Und.) are listed as new state records.

A CONTRIBUTION TO THE BIONOMICS OF THE MOSQUITOES OF ALGONQUIN PARK

The results of one season's mosquito collecting in Algonquin Park are presented giving data on relative abundance, seasonal distribution, and habitat of larvae and adults.General correlations between mosquito distribution and vegetation, and distribution and exposure are mentioned.The list of species found in the Park now includes 3 species of Anopheles, 17 of Aedes, 3 of Culiseta, 2 of Culex, 1 of Wyeomia, and 1 of Mansonia. Twenty-one of these 27 species have been taken biting man. Of these the most common in order of time of peak abundance were Aedes communis, Aedes punctor, Mansonia perturbans, and Aedes canadensis.

Distribution, Life History, and Morphological Variations of the Southern Brook Lamprey, Ichthyomyzon gagei

SINCE its original description, the southern brook lamprey, Ichthyomyzon gagei Hubbs and Trautman (1937), has received little attention. The original description was based on 10 adults and 2 ammocoetes from Alabama, Louisiana, and Oklahoma. Additional data have been added by the few brief papers mentioned below, which supply some information on geographical distribution, size, and habitat. This paper summarizes the available information regarding extensions of the known range of the species, and presents a description of the habitats of larvae and of spawning areas, observations on spawning habits and fecundity, notes on the growth and development of ammocoetes, and morphological variations within the species. Acknowledgements.-Reeve M. Bailey, University of Michigan Museum of Zoology (UMMZ), confirmed the identification of the specimens collected in 1948. Robert R. Miller loaned specimens for study. Ernest C. Lachner examined type material in the U. S. National Museum (USNM). Edgar Evans, of Tallahassee, Florida, loaned his material and gave permission to use data in his unpublished master's thesis. Other persons who loaned specimens were William M. McLane, Florida Game and Freshwater Fish Commission; Edward C. Raney, Cornell University (CU); Ralph W. Yerger, Florida State University (FSU); Royal D. Suttkus, Tulane University (TU); and Clark Hubbs, University of Texas (UT).