Changes in spatial and temporal variability of prey affect functional connectivity of larval and juvenile cod

2017 ◽  
Vol 74 (6) ◽  
pp. 1826-1837 ◽  
Author(s):  
R. Gregory Lough ◽  
Elisabeth A. Broughton ◽  
Trond Kristiansen
Keyword(s):  
Spatial Distribution ◽  
Functional Connectivity ◽  
Early Life ◽  
Gut Contents ◽  
Life Stages ◽  
Early Life Stages ◽  
Potential Growth ◽  
Growth And Survival ◽  
Important Prey ◽  
Pelagic Juveniles

Abstract Changes in structural connectivity as it can affect functional connectivity, the biological and behavioural responses of an organism, has been examined here over 2 contrasting years when the spatial distribution of larval and juvenile cod and their prey shifted from the flank to the crest on Georges Bank. New data on the gut contents of pelagic juvenile cod are compared with known prey distributions, potential growth and how climate warming can change connectivity in this region. Centropages spp. was the most important prey for pelagic juveniles, especially in June 1987 when they had high abundance on the crest and were dominant in the cod stomachs. In June 1986, copepod abundance was low where the juveniles were distributed along the flank. The potential growth of juvenile cod was greater in June 1987, consistent with the higher abundance of Centropages spp., and with higher recruitment survival, compared with June 1986. Annual changes in the spatial distribution of cod early life stages within the environment of cold or warm years can have different impacts on their growth and survival. Whereas the small copepods, Pseudocalanus spp., are primary prey for cod larvae and very abundant in cold years, larger copepods, Calanus finmarchicus and Centropages spp., are important prey for the pelagic juveniles and the latter species can have a high impact in warm years on the crest. The different spatial structure during cold or warm years provides an explanation why different year classes respond differently to environmental change. Depending on the presence or absence of specific prey, the functional connectivity response changes pathways that determine the growth and survival of early life stages and ultimately a role in recruitment.

Feeding ecology of early life stages of striped bass (Morone saxatilis) along an estuarine salinity-turbidity gradient, St. Lawrence Estuary, Canada

2019 ◽  
Vol 41 (4) ◽  
pp. 507-520 ◽  
Author(s):  
L Vanalderweireldt ◽  
P Sirois ◽  
M Mingelbier ◽  
G Winkler
Keyword(s):  
Striped Bass ◽  
Feeding Ecology ◽  
Early Life ◽  
Morone Saxatilis ◽  
Early Summer ◽  
Gut Contents ◽  
Life Stages ◽  
Early Life Stages ◽  
Lawrence Estuary ◽  
Feeding Niche

Abstract After being extirpated from the St. Lawrence River in the 1960s, striped bass (Morone saxatilis) were reintroduced to the estuary in 2002 and by 2008, they were naturally reproducing. To document the habitat use and feeding ecology of this reintroduced population, we examined the gut contents of 333 larvae and juveniles. Samples were collected in four estuarine habitats in 2014: the upstream freshwater section (UP), the oligohaline (O-ETM) and the mesohaline (M-ETM) estuarine turbidity maximum zones, and the downstream polyhaline section (DOWN). In June, pelagic larvae developed in the UP and the O-ETM, feeding mainly on copepods such as Eurytemora affinis. The O-ETM exhibited better suitable feeding conditions compared to the UP, likely due to the presence of Bosmina sp. as a primary prey. After July, striped bass shifted to larger prey items, consuming mainly dipteran pupa in upstream littoral habitats and gammarids and mysids in downstream habitats. In the early summer, the UP provided a high-quality nursery habitat and as the season progressed, the smallest juveniles dispersed downstream and improved their feeding success by exploiting a new feeding niche. This observation suggests that being distributed throughout the estuary may increase the potential survival of striped bass early life stages.

Influence of environmental conditions on spatial distribution and abundance of early life stages of Antarctic silverfish,Pleuragramma antarcticum(Nototheniidae), in the Ross Sea

2010 ◽  
Vol 22 (3) ◽  
pp. 243-254 ◽  
Author(s):  
Mario La Mesa ◽  
Barbara Catalano ◽  
Aniello Russo ◽  
Silvio Greco ◽  
Marino Vacchi ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Early Life ◽  
General Circulation ◽  
Ross Sea ◽  
Life Stages ◽  
Early Life Stages ◽  
Pleuragramma Antarcticum ◽  
Antarctic Silverfish ◽  
The Antarctic ◽  
Western Ross Sea

AbstractThe Antarctic silverfishPleuragramma antarcticumBoulenger is the dominant fish species in the high Antarctic zone, playing a key role in the Ross Sea midwater shelf ecosystem. Unlike other notothenioids, it is holoplanktonic species, spending its entire life cycle in the water column. Early life stages ofP. antarcticumare generally found in the upper 200 m and their spatial distribution is largely affected by water masses and general circulation. To understand better the mechanisms involved in the geographical distribution of the Antarctic silverfish within the western Ross Sea, an analysis of abundance and distribution was carried out in relation to oceanographic conditions. Samples were collected in summer during the 1998, 2000 and 2004 Italian cruises, covering the majority of the western sector of the Ross Sea. Overall 127 stations were sampled using standard plankton nets for biological samples and CTD and XBT to record abiotic parameters. Although all surveys were in December–January, the yearly results differed in terms of relative abundance of larval developmental stages and of oceanographic characteristics. The 1997–98 samples were characterized by very low abundance overall and by the virtual absence of early larvae. In summers 1999–2000 and 2003–04 the abundance ofP. antarcticumwas one order of magnitude higher than in the earlier season. In 1999–2000 catches were mainly composed of pre-flexion larvae and late postlarvae, while in 2003–04 catches were made up of pre-flexion larvae and juveniles. In January 2000 the Ross Sea summer polynya was fully open as the pack ice was almost completely melted, whereas in January 1998 and 2004 the opening of the polynya was considerably delayed. As a consequence, a delay in phytoplankton blooms and a decrease in primary production were observed in the summer seasons 1998 and 2004 with respect to 2000. The spatial distribution of early life stages, that were confined to the continental shelf and shelf break of the Ross Sea, generally appeared to be positively influenced by transition zones (oceanographic fronts). In addition, most of catches were recorded on or in close proximity to the banks (Pennell, Mawson, Ross and Crary) that characterize the continental shelf of the Ross Sea. On the basis of present findings and literature data, a link between the general circulation in the western Ross Sea and the distribution pattern of the early life stages ofP. antarcticumhas been developed.

Spatial distribution of Atlantic salmon (Salmo salar) breeders: among- and within-river variation and predicted consequences for offspring habitat availability

2010 ◽  
Vol 67 (12) ◽  
pp. 1993-2001 ◽  
Author(s):  
Anders Gravbrøt Finstad ◽  
Sigurd Einum ◽  
Leif Magnus Sættem ◽  
Bjart Are Hellen
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Early Life ◽  
Skewed Distribution ◽  
Habitat Availability ◽  
Life Stages ◽  
Early Life Stages ◽  
Juvenile Dispersal ◽  
Atlantic Salmon Salmo Salar

The spatial distribution of breeders within populations may have important implications for offspring habitat availability in species where mobility of early life stages is restricted. Here we address this issue using time series of spawner distributions from eight Norwegian Atlantic salmon ( Salmo salar ) populations. Whereas spawners distribute themselves uniformly along the length of the rivers in some populations, others show a heavily skewed distribution. Linear mixed models identified pronounced and temporally consistent among-population differences in spawner distributions. Using a model of limited juvenile dispersal from nests following emergence, we show that the observed spawner distributions are predicted to result in significant proportions of rivers being inaccessible for young of the year during early life stages, and the magnitude of this effect differs among populations (e.g., ranging from 27% to 59% for dispersal distance of 250 m). Thus, assuming population regulation during early but not later juvenile stages, consistent differences in spawner distributions among populations such as those observed here may translate into differences in productivity (i.e., carrying capacity) as well as egg densities required for populations to reach their spawning targets.

Contrasting links between growth and survival in the early life stages of two flatfish species

2021 ◽  
Vol 254 ◽  
pp. 107314
Author(s):  
Ana Lígia Primo ◽  
Ana Catarina Vaz ◽  
Daniel Crespo ◽  
Filipe Costa ◽  
Miguel Pardal ◽  
...  
Keyword(s):  
Early Life ◽  
Life Stages ◽  
Early Life Stages ◽  
Growth And Survival ◽  
Flatfish Species

scholarly journals Spatial distribution of sardine and anchovy early life stages along the eastern Adriatic Sea

2015 ◽  
Vol 2 ◽  
Author(s):  
Zorica Barbara ◽  
Cikes Kec Vanja ◽  
Brzulja Goran ◽  
Kraljević Viktor
Keyword(s):  
Spatial Distribution ◽  
Early Life ◽  
Adriatic Sea ◽  
Life Stages ◽  
Early Life Stages
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