scholarly journals Ecosystem structure in the Iceland Sea and recent changes to the capelin (Mallotus villosus) population

2012 ◽  
Vol 69 (7) ◽  
pp. 1242-1254 ◽  
Author(s):  
Ólafur K. Pálsson ◽  
Astthor Gislason ◽  
Hafsteinn G. Guðfinnsson ◽  
Björn Gunnarsson ◽  
Sólveig R. Ólafsdóttir ◽  
...  
Keyword(s):  
Seasonal Pattern ◽  
Fish Fauna ◽  
Late Summer ◽  
Pelagic Fish ◽  
Trophic Levels ◽  
Ecosystem Structure ◽  
Mallotus Villosus ◽  
Capelin Mallotus Villosus ◽  
History Of ◽  
Clear Seasonal Pattern

Abstract Pálsson, Ó. K., Gislason, A., Guðfinnsson,  H. G., Gunnarsson, B., Ólafsdóttir, S. R., Petursdottir, H., Sveinbjörnsson, S., Thorisson, K., and Valdimarsson, H. 2012. Ecosystem structure in the Iceland Sea and recent changes to the capelin (Mallotus villosus) population. – ICES Journal of Marine Science, 69: . The objective of the Iceland Sea Ecosystem Project was to analyse principal ecosystem patterns, including the life history of capelin. Ten surveys were conducted for this purpose between 2006 and 2008, and hydrographic data from 1970 to 2011 were analysed. Long-term temporal patterns indicate an increase in the temperature of surface and intermediate waters during recent years in the Iceland Sea. The phytoplankton consisted mainly of diatoms in spring, with flagellates and dinoflagellates appearing later in the year. Zooplankton and fish were dominated by a few species. In late summer, the pelagic foodweb ranged between trophic levels 2.4 and 3.6. Trends in nutrients and primary production showed a clear seasonal pattern with a spring bloom in late May, followed by a peak in secondary production in July/August. The spatial structure of the lower ecosystem levels in summer was stable across the 3 years, determined mainly by the structure of the water masses. The pelagic fish fauna consisted primarily of adult pelagic fish and transient numbers of larval species. The spatial pattern of capelin indicated northward displacement of 0-group capelin and westward displacement of older capelin in recent years. The annual biomass was estimated at 3.8 million tonnes of phytoplankton, ∼21 million tonnes of zooplankton, and 1.0 million tonnes of fish.

Gametogenesis in capelin, Mallotus villosus (Müller), in the northwest Atlantic Ocean

2003 ◽  
Vol 81 (9) ◽  
pp. 1511-1523 ◽  
Author(s):  
S R Flynn ◽  
M P.M Burton
Keyword(s):  
Atlantic Ocean ◽  
Reproductive Biology ◽  
Mallotus Villosus ◽  
Northwest Atlantic ◽  
Important Prey ◽  
Resource Managers ◽  
Capelin Mallotus Villosus ◽  
Ovarian Wall ◽  
History Of ◽  
Post Spawning

Capelin (Mallotus villosus) can be regarded as the most important prey item in the northwest Atlantic Ocean. The health and availability of this species are of fundamental importance for the successful growth and reproduction of many other fishes, whales, and birds. In spite of the clear need to understand this species, the life history of the capelin, especially its reproductive biology, is not well understood. This study substantially improves our knowledge of the reproductive biology of capelin and should be of particular interest to resource managers and administrators. Capelin gonads were analysed over three successive seasons using fish collected during beach spawning (June and July 1993, July 1994, July 1995) or trawled between spawnings, with 11 separate samples (fall, winter, and spring from October 1993 to June 1995). Few immature fish were collected in the trawls; 13/130 (10%) males and 3/150 (2%) females. No recovering (postspawning) males were found in the trawls, but 8/150 (5.3%) recovering females were identified on the basis of large residual oocytes (ovulated or unovulated) and (or) (in the fall) a thicker ovarian wall. Recovering females were identified as late as 10 months post spawning on the basis of residual oocytes. The essential semelparity of males was supported by a lack of apparent spermatogonia during advanced spermatogenesis, whereas the females' capacity to spawn in a subsequent year (iteroparity) was confirmed by the presence of small nonvitellogenic oocytes when other cells were in late oogenesis, in addition to the identification of recovering fish. Oocytes were separable into four stages (potential year classes) and changes occurred in all oocyte stages throughout the cycle of oogenesis. Gametogenesis was more advanced in longer fish, indicating that larger fish spawn earlier than smaller fish.

scholarly journals Spatial and temporal changes in assemblage structure of zooplankton and pelagic fish in the eastern Bering Sea across varying climate conditions

2015 ◽  
Vol 181 (2) ◽  
pp. 141-160
Author(s):  
Lisa B. Eisner ◽  
Elizabeth C. Siddon ◽  
Wesley W. Strasburger
Keyword(s):  
Bering Sea ◽  
Late Summer ◽  
Temporal Changes ◽  
Pelagic Fish ◽  
Small Copepod ◽  
Climate Conditions ◽  
Eastern Bering Sea ◽  
Fish Samples ◽  
Spatial And Temporal Changes ◽  
Capelin Mallotus Villosus

Zooplankton and pelagic fish samples collected on the eastern Bering Sea shelf in late summer 2003-2010 were used to evaluate spatial and temporal changes in the plankton and nekton community structure. The zooplankton were sampled by vertical towing of a Juday net (168 μm mesh) and oblique towing of a Bongo net (505 μm mesh), and pelagic fish were caught by midwater rope trawl. The communities were compared across climate regimes (in relatively warm and cold years), by latitude (in the northern and southern parts of the shelf), and by water depth (in the inner, middle, and outer domains of the shelf). Zooplankton were dominated by the small copepod Oithona spp. in warm years but relatively larger copepods Pseudocalanus spp. and Acartia spp. in cold years. Notably, the large copepod Calanus spp., an important energy-rich prey for fish, were more abundant in cold years than warm years. Age-0 walleye pollock Gadus chalcogrammus were more abundant in warm years, while capelin Mallotus villosus were abundant within cold-year communities over the northern shelf. Latitudinal variations in communities were more prominent in the cold years, particularly in 2007 and 2010. Cross-shelf variations were evident, particularly for large zooplankton and fish, with communities corresponding to specific oceanographic domains. Outer shelf communities varied less than inner and middle shelf communities between warm and cold periods, suggesting that this region may be less impacted by climate variability. An understanding of the overlap of zooplankton (prey) and fish communities within specific shelf regions or climate regimes may provide information for ecosystem-based approaches to fisheries management.

The life history of Hysterothylacium analarum Rye and Baker, 1984 (Nematoda: Anisakidae) in Lepomis gibbosus (Pisces: Centrarchidae) in southern Ontario, Canada

1992 ◽  
Vol 70 (8) ◽  
pp. 1576-1584
Author(s):  
Leslie A. Rye ◽  
Michael R. Baker
Keyword(s):  
Seasonal Pattern ◽  
Late Summer ◽  
Intestinal Lumen ◽  
Lepomis Gibbosus ◽  
Fourth Stage ◽  
Larval Stages ◽  
Second Stage ◽  
Third Stage ◽  
History Of ◽  
Gravid Females

Larval stages of Hysterothylacium analarum are described from Lepomis gibbosus in Dawson Pond, Ontario (45°10′N, 78°50′W). Second-stage larvae were easily distinguished from all other stages by the presence of a conical boring tooth. Third-stage larvae lacked both a boring tooth and lips. Fourth-stage larvae had well-developed lips. The ratio of ventricular appendage length to intestinal caecum length varied greatly between larval stages and adults. Prevalence and intensity of larval stages and adult H. analarum showed a distinct seasonal pattern, with one generation of adult worms per year. In spring, third-stage larvae left nodules on the intestinal serosa of L. gibbosus and migrated to the intestinal lumen, where they rapidly moulted to the fourth-stage and then to adult worms. Eggs collected from gravid females developed to second stage larvae in approximately 5 days under laboratory conditions. In natural infections in the late summer second-stage larvae were found in nodules on the serosa and in the mesentery. Larvae apparently moulted to the third stage and overwintered in the nodules as third-stage larvae.

Seasonal and Vertical Distribution and Growth of Juvenile and Adult Capelin (Mallotus villosus) in the St. Lawrence Estuary and Western Gulf of St. Lawrence

1977 ◽  
Vol 34 (11) ◽  
pp. 2015-2029 ◽  
Author(s):  
R. F. J. Bailey ◽  
K. W. Able ◽  
W. C. Leggett
Keyword(s):  
Vertical Distribution ◽  
Large Population ◽  
Food Resource ◽  
Late Summer ◽  
Rapid Decline ◽  
Lower Estuary ◽  
Mallotus Villosus ◽  
Lawrence Estuary ◽  
Capelin Mallotus Villosus ◽  
Saguenay River

The distribution of juvenile and adult capelin (Mallotus villosus) in the estuary and western Gulf of St. Lawrence was similar in 1974 and 1975. Juvenile (age 1 and 2) capelin were largely restricted to the western Gulf, which appears to serve as a nursery area for larval and juvenile capelin, throughout the summer and fall. During the summer and early fall capelin occurred in small schools which were widely distributed over most of the western Gulf. Concentration of juvenile and adult capelin into dense schools and their movement into the lower estuary in November were interpreted as the initiation of a contranatant migration to the spawning areas in the estuary. Spawning occurred first in the upper estuary (April–May) and was progressively later in the lower estuary and western Gulf. Postspawning mortality was high and resulted in a rapid decline in the abundance of adult capelin in the estuary and western Gulf following spawning. A concentration of juvenile capelin in and near the mouth of the Saguenay River throughout the year was apparently supported during the late summer by zooplankton production in the river. These fish, in turn, contribute heavily to the food resource of a large population of beluga whales that summer in the area. Capelin from the study area reach a greater mean size at the end of the 1st yr than do those from Newfoundland, Labrador, and Greenland. Subsequent growth was similar to that of stocks from southern Newfoundland but was faster than in stocks from northern Newfoundland and Labrador. Capelin populations in the estuary and western Gulf matured earlier and had younger mean ages than those from other areas in the Canadian Atlantic. Key words: capelin, Mallotus villosus, Gulf of St. Lawrence, seasonal distribution, vertical distribution, growth, spawning

scholarly journals The contrasting evolution of twin volcanic lakes (Monticchio, Mt. Vulture, Italy) inferred from literature records

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Renato Spicciarelli ◽  
Aldo Marchetto
Keyword(s):  
Algal Blooms ◽  
Trophic Status ◽  
Human Impacts ◽  
Seasonal Pattern ◽  
Nitrogen Concentration ◽  
Ecological Status ◽  
Late Summer ◽  
Lake Area ◽  
Special Area ◽  
History Of

Lago Piccolo and Lago Grande di Monticchio lie in the collapsed caldera of the volcanic structure of Mt. Vulture (Basilicata, Italy). In over two centuries, a number of studies on their water and on their submerged and riparian vegetation, were carried out, demonstrating an interesting biodiversity. The entire lake area, which is impacted by strong tourist pressure, is part of the "Monte Vulture" Special Area of Conservation (SAC IT9210210). The aim of this paper is to review the literature studies on these lakes, in order to identify the more suitable limnological parameters to infer the history of the trophic status of the two lakes. For this reason, we assess the current ecological status of the two lakes on the basis of physical, chemical and biological analyses deriving from two recent surveys carried out in 2005-2007 and in 2015, and compare these data with sparse, but relevant, historical records, in order to assess how human impacts affected both these lakes and to understand the differences in their present trophic status. Because of its peculiar water chemistry, Lago Piccolo is resulted in good and stable ecological conditions. On the contrary, water transparency of Lago Grande came out very low in summer, while total phosphorus and nitrogen concentration are proved high, leading to the persistence of critical environmental conditions in this lake, with high algal biomass and durable algal blooms in late summer, dominated by cyanobacteria. Finally, in absence of standard protocols and seasonal samplings, the macrophyte maximum growing depth should be considered the more reliable indicator of trophic status among those available for these specific lakes, being relatively independent from sampling methods and seasonal pattern.

scholarly journals Scyphomedusae and Ctenophora of the Eastern Adriatic: Historical Overview and New Data

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 186
Author(s):  
Branka Pestorić ◽  
Davor Lučić ◽  
Natalia Bojanić ◽  
Martin Vodopivec ◽  
Tjaša Kogovšek ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Seasonal Pattern ◽  
Geographical Location ◽  
Distribution Patterns ◽  
Mnemiopsis Leidyi ◽  
Future Studies ◽  
Phenological Data ◽  
Pelagia Noctiluca ◽  
Regional Trends ◽  
Clear Seasonal Pattern

One of the obstacles to detecting regional trends in jellyfish populations is the lack of a defined baseline. In the Adriatic Sea, the jellyfish fauna (Scyphozoa and Ctenophora) is poorly studied compared to other taxa. Therefore, our goal was to collect and systematize all available data and provide a baseline for future studies. Here we present phenological data and relative abundances of jellyfish based on 2010–2019 scientific surveys and a “citizen science” sighting program along the eastern Adriatic. Inter-annual variability, seasonality and spatial distribution patterns of Scyphomedusae and Ctenophore species were described and compared with existing historical literature. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for meroplanktonic Scyphomedusae Aurelia solida, Rhizostoma pulmo, and to a lesser extent Chrysaora hysoscella, Cotylorhiza tuberculata and Discomedusa lobata. Holoplanktonic Pelagia noctiluca also formed large aggregations, which were seasonally less predictable and restricted to the central and southern Adriatic. Four species of Ctenophora produced blooms limited to a few areas: Bolinopsis vitrea, Leucothea multicornis, Cestum veneris and the non-native Mnemiopsis leidyi. However, differences between Adriatic subregions have become less pronounced since 2014. Our results suggest that gelatinous organisms are assuming an increasingly important role in the Adriatic ecosystem, which may alter the balance of the food web and lead to harmful and undesirable effects.

scholarly journals Early life growth is affecting timing of spawning in the semelparous Barents Sea capelin (Mallotus villosus)

2021 ◽  
pp. 102614
Author(s):  
Florian Berg ◽  
Samina Shirajee ◽  
Arild Folkvord ◽  
Jane Aanestad Godiksen ◽  
Georg Skaret ◽  
...  
Keyword(s):  
Early Life ◽  
Barents Sea ◽  
Mallotus Villosus ◽  
Capelin Mallotus Villosus ◽  
Timing Of Spawning

Channel head dynamics: capelin (Mallotus villosus) aggregation in the tidally driven upwelling system of the Saguenay - St. Lawrence Marine Park's whale feeding ground

2002 ◽  
Vol 59 (2) ◽  
pp. 197-210 ◽  
Author(s):  
Yvan Simard ◽  
Diane Lavoie ◽  
François J Saucier
Keyword(s):  
Circulation Model ◽  
Feeding Strategies ◽  
Total Biomass ◽  
Balaenoptera Acutorostrata ◽  
Mallotus Villosus ◽  
Tidal Dynamics ◽  
Lawrence Estuary ◽  
Fin Whale ◽  
Capelin Mallotus Villosus ◽  
Tidally Driven

Capelin (Mallotus villosus) tridimensional distribution at the head of the Laurentian Channel in the St. Lawrence estuary was investigated using 38- and 120-kHz acoustic surveys in the summers of 1994, 1995, 1997, and 1998. The results are interpreted with the help of a high-resolution tridimensional tidal circulation model. Total biomasses were small (93–4583 t) and showed rapid fluctuations, whereas mesoscale distribution was more constant. Capelin tended to occupy the very end of the channel head, especially the slopes and shallows surrounding the basins. This pattern did not coincide with the krill distribution, but the two total biomass series were significantly correlated. Capelin tidal dynamics is characterized by herding of capelin against the channel head slopes by the starting flooding currents, followed by an upwelling over the sills and shallows during maximum flood currents, and a return to the channel by the surface outflow during ebb. Each side of the channel head has a distinct capelin retention tidal cycle involving passive advection, swimming, and the two-layer estuarine circulation. This capelin distribution and tidal dynamics closely match the local fin whale (Balaenoptera physalus) and minke whale (Balaenoptera acutorostrata) distributions observed from the whale-watching fleet and typical tidal feeding strategies at the channel head.

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