Distribution Of Ichthyoplankton Research Articles

Abundance and Distribution of Ichthyoplankton in Narragansett Bay, Rhode Island, 1989-1990

An ichthyoplankton survey (18 stations in seven sampling sectors) was conducted in Narragansett Bay in 1990 to provide information on abundance, distribution, and seasonal occurrence of eggs and larvae of estuarine fishes, including seasonal migrants. An additional goal was to examine changes in species composition, abundance, and distribution occurring since the last baywide survey in 1972–73. The taxonomic composition of eggs and larvae in 1990 (41 species in 25 families from 684 plankton samples) and in 1972–73 (43 species in 28 families from 6900 samples) was similar. Maximum abundance of fish eggs occurred in June and larvae in July, minimum abundance in September to February. Species diversity was greatest in May–July and lowest during January in both surveys. However, egg and larval densities in 1990 were considerably lower than in 1972–73. Bay anchovy, tautog, and cunner accounted for 86% of the eggs and 87% of the larvae in the bay in 1990. These three species accounted for only 55% of the eggs and 51% of the larvae in 1972–73, with menhaden accounting for another 18% of the eggs and 34% of the larvae. Searobins, scup, and butterfish eggs were common in 1973 (19%) but rare in 1990 (2%). Ichthyoplankton abundance for several of the most abundant species was significantly lower (p<0.05) in the Providence River, upper bay, and Greenwich Bay in 1990 than in 1972–73. Density of fish eggs and larvae in the lower portions of the bay was lower in 1990 for some species but not others. Distribution data suggested a general down-bay shift in density in 1990. *** DIRECT SUPPORT *** A01BY085 00015

Cross-frontal transport and distribution of ichthyoplankton associated with Chesapeake Bay plume dynamics

Cross-frontal transport associated with upwelling conditions was responsible for modifying ichthyoplankton distributions across the inner continental shelf waters off the Chesapeake Bay during late August 1988. Two ichthyoplankton assemblages characteristic of the Chesapeake Bay plume and inner-continental shelf waters were defined using multivariate analysis. Members of the plume assemblage ( Anchoa spp., Menticirrhus spp., and Micropogonias undulatus) were not retained within the Chesapeake Bay plume, but were instead advected 60 km onto the shelf within a low-salinity water mass. A second assemblage, dominated by several shelf-spawned taxa including Etropus microstomus, Prionotus spp. and Centropristis striata was distributed across the shelf. Atlantic croaker, M. undulatus, previously thought to be shelf-spawned exhibited a length-frequency distribution that increased from inshore to offshore, and paralleled that of Anchoa spp. This cross-shelf distribution, and the abundance of small (<3.5 mm), pre-flexion larvae inshore suggests that M. undulatus spawned near the plume front and were subsequently transported offshore with the plume assemblage. A mechanism for rapid cross-frontal transport is described. These findings suggest that the transport and recruitment patterns previously described for this taxon in Chesapeake Bay need to be re-examined. Larval survival and recruitment success of shelf-spawned estuarine species, like M. undulatus, are likely tied to oceanographic conditions on the inner shelf related to upwelling and downwelling conditions and plume dynamics, rather than to simple, wind-driven recruitment mechanisms.

Short term variability in larval fish assemblages of the Sydney shelf:tracers of hydrographic variability

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 178:1-15 (1999) - doi:10.3354/meps178001 Short term variability in larval fish assemblages of the Sydney shelf: tracers of hydrographic variability Kimberley A. Smith1,*, Mark T. Gibbs2,3, Jason H. Middleton2, Iain M. Suthers1 1School of Biological Science, University of New South Wales, Sydney, New South Wales 2052, Australia 2School of Mathematics, University of New South Wales, Sydney, New South Wales 2052, Australia 3Department of Marine Science, University of Otago, PO Box 56, Dunedin, New Zealand *E-mail: marsci@unsw.edu.au ABSTRACT: The among- and within-night changes in the vertical and horizontal distribution of ichthyoplankton assemblages across the Sydney continental shelf, SE Australia, were examined in relation to concurrent changes in hydrography. Of the environmental factors examined, spatial position (sampling depth, distance from shore), water temperature and sampling depth relative to the base of the mixed layer gave the best explanation for variability in assemblage distributions. There was good agreement between observed changes in ichthyoplankton distributions and among-night variability in the cross-shelf temperature and current fields. Ichthyoplankton assemblages functioned as short term, biological tracers of hydrographic variability. Our observations suggest several cross-shelf advective processes, including a recirculation cell over the shelf, could retain passively drifting ichthyoplankton within the shelf region and also minimise longshore drift. The multivariate analysis used was an effective method of examining patterns within and between large, highly variable biological and environmental data sets. KEY WORDS: Ichthyoplankton · Hydrography · Biological tracer · Larval retention · Multivariate Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 178. Publication date: March 17, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

The effect of environmental conditions on the distribution of eggs and larvae of anchovy (Engraulis encrasicolus L.) in the Black Sea

Abstract Recent events in the Black Sea have had a severe impact on all compartments of the ecosystem, including ichthyoplankton. The distribution of eggs and larvae of the anchovy, the major commercial fish species, was investigated in relation to ambient conditions in the southern Black Sea during July 1992, August 1993, and June–July 1996. Average highest egg and larva numbers were observed in June–July 1996. Ichthyoplankton distribution was closely connected with the hydrography. Besides surface temperature and salinity, among the numerous biotic parameters tested, abundance of fodder zooplankton and of the ctenophore Mnemiopsis leidyi showed significant correlations with the distribution of either eggs or larvae of the anchovy. The results help in explaining the shift observed in the spawning grounds.

Drift of ichthyoplankton in two channels of the Paraná River, between Paraná and Mato Grosso do Sul states, Brazil

Analysis of drift of ichthyoplankton in two channels in the River Paraná, Brazil, were made. Sampling was undertaken from October 1995 to April 1996 during nychthemeral cycles. Water samples were collected to determine several environmental variables. Eggs densities largely differed to layers, times of day and months. In both the channels, highest occurrence of eggs was detected between January and March; greater concentrations at the bottom, during night. With regard to larvae, densities were significantly different in channels, times of days and months. Maximum occurrences were seen in the right channel, in both layers, with largest capture between January and March. Surface of the both channels presented highest density of larvae during night. Water temperature, electrical conductivity and flux velocity were different in the two channels, however, these variables and larvae density didn't showed correlations. This indicates that there was another possible factor, might be influencing the distribution of ichthyoplankton.

Displacement of diverse ichthyoplankton assemblages by a coastal upwelling event on the Sydney shelf

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 176:49-62 (1999) - doi:10.3354/meps176049 Displacement of diverse ichthyoplankton assemblages by a coastal upwelling event on the Sydney shelf Kimberley A. Smith*, Iain M. Suthers School of Biological Science, University of New South Wales, Sydney, New South Wales 2052, Australia *E-mail: marsci@unsw.edu.au ABSTRACT: The influences of upwelling-favourable winds and thermocline displacement on the distribution of temperate/tropical ichthyoplankton assemblages were determined from vertically stratified plankton hauls across the Sydney shelf, southeastern Australia. Five stations were sampled along a shore-normal transect off Sydney, Australia, on 3 or 4 consecutive nights during January and April 1994. High taxonomic diversity (111 ichthyoplankton families) was attributed to the convergence of temperate and tropical waters in this region. Total larval abundance was higher in January than in April, reflecting the spawning times of many coastal taxa. In both months, highest larval density and taxonomic diversity were associated with the interface between the mixed layer and the thermocline. In April, a period of upwelling-favourable winds resulted in the offshore displacement of the nearshore mixed layer, as well as numerous shelf-spawned larvae (e.g. Centroberyx affinis, Chromis hypsilepsis, Arripis trutta) from the nearshore region, and coincided with the injection of deeply distributed mesopelagic larvae into the nearshore zone (e.g. Scopelosaurus sp., Melamphaes sp.). Shelf-spawned larvae were displaced to the outer shelf, where they were still associated with the mixed layer/thermocline interface. Dynamic ichthyoplankton distributions are interpretable, at least at a scale of weeks, by considering larvae as tracers of the local hydrography. KEY WORDS: Ichthyoplankton assemblages · Hydrography · Upwelling · Thermocline Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 176. Publication date: January 18, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Influence de la circulation à long terme sur la répartition des organismes zooplanctoniques dans la Baie de Campeche, Mexique

A space-time approach is adopted in an attempt to understand the long-term influence of currents on the spatial pattern distribution of zooplankton, ichthyoplankton, and fish larvae communities in the Bay of Campeche, Mexico. The analysis is performed using results of a hydrodynamic numerical model, and zooplankton and ichthyoplankton abundances. Three fish larvae communities were identified in the Bay, on the basis of its physiography, i.e.: “neritic fluvio lagoon influence”, “neritic” and “oceanic” communities. A cyclonic eddy is formed in the Bay and drifts westward, facilitating transport and distribution of planktonic organisms. The eddy provides larvae transport from oceanic areas to the coastal areas and vice-versa. The seasonal distribution of fish larvae is highly influenced by the position of the eddy. The biomass pattern and fish larvae density observed in the coastal area off the Grijalva-Usumacinta delta are governed by the coastal front.

Beyond hydrography: daily ichthyoplankton variability and short term oceanographic events on the Sydney continental shelf

Surface ichthyoplankton concentrations along a shore-normal transect across the Sydney continental shelf and upper slope changed between three replicate nights in January and April of 1994. Over 70 families of fish were recorded, which, during January, included: Myctophidae (49% of individuals), Carangidae (14%), Gonostomatidae (11%) and Pomacentridae (8%); and during April included: Gonorhynchidae (43%), Myctophidae (10%), Berycidae (11%) and Serranidae (6%). Multidimensional scaling analysis identified inshore and offshore communities, which nightly moved between the nearshore and mid-shelf stations. During January no distinct near-surface water masses could be identified from the temperature-salinity data, although the shelf waters were under the influence of forcing by the local wind stress and the East Australian Current. Good agreement between the cross-shore transport in the near-surface layer and the temporal variability of the icthyoplankton was nevertheless found. The sampling during April was performed during a period of relatively steady oceanographic conditions, and two water masses were identified from the hydrographic data. Temporal ichthyoplankton variability at any station was correspondingly less during the April period and stable inshore and offshore communities were identified, that shifted with characteristic water masses. The results presented in this paper demonstrate that the large variance often associated with ichthyoplankton distribution within a similar water mass may be interpreted by the dynamics in cross-shelf flows, which has implications for the selection of control sites used when studying environmental impacts of coastal outfalls.

Dynamics of Ichthyoplankton in the Kanawha River, West Virginia

ABSTRACT Ichthyoplankton distribution and abundance were examined in the upper Kanawha River in the main channel, main-channel border (nearshore), and shoreline habitats. Drift of larval fish was comprised of 25 taxa distributed among 11 families and occurred from early April to late August, with peak densities in early June. Fish larvae appeared and densities peaked at water temperatures of 8.5°C and 22°C, respectively. Larval freshwater drum (Aplodinotus grunniens) was the most abundant taxa followed by Clupeidae, common carp (Cyprinus carpio), and other Cyprinidae. Clupeidae, common carp, and freshwater drum dominated main channel and nearshore collections. Cyprinidae, Catostomidae, and bluegill sunfish (Lepomis macrochirus) dominated shoreline collections. Most fish larvae (99%) collected in the main channel and nearshore habitats were protolarvae, while the larger larvae, meso- and metalarvae, were more abundant along the shoreline. In the main channel, fish larvae and eggs were generally distributed throughout the water column, but at times were more abundant on the bottom. Generally, larval fish densities were lower in the main channel compared to nearshore habitats.

Ichthyoplankton distribution and dispersal in the Tsitsikamma National Park marine reserve, South Africa

The nature of ichthyoplankton distribution within the Tsitsikamma National Park marine reserve was investigated in an attempt to evaluate the potential for export of larvae of commercially and recreationally important reef species to adjacent, exploited areas. Monthly, inshore ichthyoplankton samples were taken using Bongo nets over an 18-month period. Sampling sites were located over areas of high-profile reef and sand, Current-meter measurements of the area were used to determine current velocity, direction and reversal periodicity. Statistical analysis of the data was performed independently for larvae from four families: Blenniidae, Gobiesocidae, Sparidae and Engraulidae. Results suggested that blenniid and gobiesocid larvae practised active position retention throughout their pelagic phase, while this feature was less defined in sparid and engraulid larval distribution. Using larval distribution and current-meter information, projected dispersal distances for spa rid larvae, the family containing the most target commercial and recreational angling species, were estimated. The results suggest that sparid larvae are exported from the reserve to adjacent, exploited areas.

Ichthyoplankton distribution and abundance off the west coast of Ireland

The larval stages of 72 fish species were identified from plankton samples taken from off the west coast of Ireland to the Porcupine Bank during April to July 1980 and April to June 1983. Three species, pearl-side (Maurolicus muelleri), mackerel (Scomber scombrus) and blue whiting (Micromesistius poutassou), accounted for 75% of the total numbers of fish larvae. All of the major species were more abundant in 1983 than in 1980, some significantly so. Several species had their peak abundance earlier in 1983 than in 1980. Twelve species of chaetognath were also identified and their distribution and abundances indicated movements and origins of water masses.

Larval fish distribution and abundance in the Antarctic Peninsula region and adjacent waters

The spatial distribution, species composition and abundance of ichthyoplankton in the Bransfield Strait and adjacent waters were studied during two cruises in the Antarctic spring 1991/92 and summer 1992/93 seasons. A multiple plankton net (Bioness) and a Bongo net were used to collect samples at 35 stations in 1991/92 and 75 stations in 1992/93. Early larval stages (14 species) and juveniles (13 species) representing the known Bransfield Strait ichthyofauna were present in the water column. The nototheniids predominated in the entire study area. The greatest species diversity was found in the uppermost 200 m of the water column in the Bransfield Strait. Notothenia gibberifrons and Nototheniops larseni dominated in spring, whilst in summer Pleuragramma antarcticum dominated in association with N. larseni. The dominant species in the Gerlache Strait were P. antarcticum and Notothenia kempi, while P. antarcticum and Trematomus scotti were predominant in the Bellingshausen Sea area.

Is There a Separate Stock of Atlantic Cod in the Western Side of the Bay of Fundy/

Abstract Atlantic cod Gadus morhua in the Bay of Fundy are currently managed by Canada as part of a single management unit known as North Atlantic Fisheries Organization (NAFO) division 4X, although it has long been suspected that many stocks occur in that region. Through analyses of fishery and egg and larval distributions, abundance indices from research vessel surveys, tagging results adjusted for effort, and available literature, we examined the hypothesis that a separate stock of Atlantic cod occurs in the western half of the Bay of Fundy (NAFO unit areas 4Xs and 5Yb). The ichthyoplankton and fishery distribution data supported the hypothesis. In particular, ichthyoplankton data indicated spawning activity in the western side of the Bay of Fundy. The tagging data, however, indicated a high rate of exchange between the east and west sides of the Bay of Fundy. Given such interchange, creation of a separate management unit in the western Bay of Fundy will likely not yield benefits in terms of improved s...

A Preliminary Analysis of Ichthyoplankton on the Kuroshio Edge Exchange Area

Ichthyoplankton in the water column off northeastern Taiwan in the Kuroshio edge exchange area was sampled by round-mouthed ichthyoplankton net in June 1989 to understand the ichthyoplankton community structure and its linkage with the Kuroshio edge exchange process. The distribution of ichthyoplankton exhibited a pattern of: a) high density in the northwest near the East China Sea; b) low density in the southern area of the Kuroshio Current proper; and c) moderate density in the intermediate area. Canonical correlation analysis indicated a significant correlation between hydrological and biological factors.

Horizontal and vertical distribution patterns of ichthyoplankton under intense upwelling regimes off Namibia

Horizontal and vertical distribution patterns of eggs and larvae of selected fish species in the waters off Namibia during intense upwelling seasons are discussed. The material was collected in the course of several cruises carried out off Namibia during winter and spring. The coastal area was under the influence of strong upwelling, characterized by surface isotherms running parallel to the coast and, except for some slope stations, the water column from the surface to 200 m deep showed almost no stratification. Analysis of vertical distributions showed that eggs and larvae of all species were widely distributed throughout the water column, with a maximum within the upper 100 m. Spatial patterns of ichthyoplankton distributions in the northern Benguela during intense upwelling seasons show clear segregation into coast and slope (oceanic) areas. Two species, lanternfish Lampanyctodes hectoris and lightfish Maurolicus muelleri, dominated the oceanic area. In the coastal area, the most abundant species was ...

Composition, distribution and abundance of neustonic ichthyoplankton off northeastern New Zealand

Patterns in the distribution and abundance of ichthyoplankton off the northeastern coast of New Zealand were investigated. Neuston samples were collected monthly between November 1986–November 1987 at stations located 0·5, 3·2 and 6·0 km offshore from each of three locations that were separated by 3–5 km. Three abundant taxa, tripterygiids ( Forsterygion spp.), an engraulid ( Engraulis australis ) and a clupeoid ( Sardinops neopilchardus ) accounted for 80% of the total catch. Ichthyoplankton was at least three times more abundant during the winter month of July than in any other month, primarily due to the large numbers of tripterygiids. Low densities of fish larvae were found during the spring and summer, but many taxa had peaks in abundance at this time. Patterns of along-shore distribution were inconsistent; they varied between months for most taxa. In general, more fish larvae were caught at the sampling stations that were 3·2 or 6·0 km from the shore.

Spatial patterns of ichthyoplankton distribution in relation to hydrographic features in the Northern Benguela region

The spatial distribution of the most abundant eggs and larvae of teleost fish species on the continental shelf and slope off the northern Benguela region was studied in April 1986. The horizontal and vertical distribution of eggs and larvae were analysed together with environmental data, in order to determine patterns of ichthyoplankton distribution. Both species composition and relative egg and larval abundance levels exhibited important latitudinal differences during a period of quiescent upwelling with an intense intrusion of Angolan water into the system. Larval diversity was higher in the northern part of the study area, where, because of the intrusion of the warmer Angolan water, the water column was more stratified than in the southern part, where the affect of upwelling of South Atlantic Central Water was continuous and only a few species spawned. The frontal zone appeared to be a nursery ground for the most important pelagic species of the region:Trachurus trachurus capensis, Engraulis capensis, andSardinops ocellatus. Vertical egg and larval distributions showed evidence of stratification, with highest concentrations located in the uppermost 50 m. In comparison, during periods of intense upwelling, longitudinal gradients were responsible for the horizontal distribution of ichthyoplankton, and the vertical distribution of eggs and larvae were much more extensive because of the greater mixing of the water column.

Distribution and Abundance of Ichthyoplankton in the Manicouagan River Estuary, a Tributary of the Lower St. Lawrence Estuary

The species composition and relative abundance of ichthyoplankton were investigated during summer 1986 at four stations along the salinity gradient in the Manicouagan River estuary, a tributary of the lower St. Lawrence estuary. Physical characteristics of water masses indicated the presence of a strong saline front (>10‰ per km) delineating the freshwater and marine section of the Manicouagan estuary. The estuary supports a depauperate ichthyoplankton community, including four species of pelagic fish eggs and eight species of fish larvae. Species richness increased with salinity. The ichthyoplankton fauna can be divided into two distinct groups: freshwater and marine. These two groups result initially from spawning preferences exhibited by the different species abundance of freshwater larvae was maximal at the head of the estuary and marine larvae were most abundant at the most saline station. The length frequency distribution suggests that marine larvae are not effectively retained within the estuary. The Manicouagan estuary cannot be considered as a major spawning site nor an important nursery zone for any fish found in this area.

Composition, distribution and abundance of ichthyoplankton in the Sundays River Estuary

The species composition, distribution and seasonal abundance of ichthyoplankton in the Sundays River estuary was investigated at five stations from March 1986 to March 1987. Two estuarine taxa, the clupeid Gilchristella aestuaria and gobies Caffrogobius spp., accounted for 86% of the ichthyoplankton community, while the marine Mugilidae and sparid Rhabdosargus holubi together comprised 12% of the total catch. Ichthyoplankton densities were highest in the middle and upper reaches of the estuary where zooplankton stocks were greatest. Juvenile G. aestuaria predominated in the bottom waters throughout the system but the larvae were more evenly distributed (vertically) within the water column. In contrast, the mugilids were concentrated in surface waters throughout the estuary. Larvae were most abundant during spring and summer months, coinciding with the documented spawning period of most species and the peak in zooplankton biomass.

Temporal distribution of ichthyoplankton near Beaufort Inlet, North Carolina

Temporal distribution of ichthyoplankton near Beaufort Inlet, North Carolina