Sturgeons and the Aral Sea ecological catastrophe

Zholdasova, Iliya

doi:10.1007/0-306-46854-9_25

Cited by 15 publications

(11 citation statements)

References 2 publications

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“…The main point of this study then, is not to present new information on how giant kelp populations are organized during non-El Niño years or even how these populations are impacted by El Niños, but rather to demonstrate how a single comprehensive study done at multiple scales can provide substantial insight into the scale-dependent nature of ecosystem regulation, with particular attention to how an ecosystem's competitive dominant and primary habitat-forming species can be impacted by and recover from a large-scale environmental disturbance. Whether such an approach can be generalized to other ecosystems is unclear, but it is clear that many disturbances occur over large geographic areas (Zholdasova 1997;Carpenter 1998;Romme et al 1998;Turner and Dale 1998) and that ecological research on their impacts will benefit by incorporating scale-dependent analyses (Dayton and Tegner 1984a;Levin 1992Levin , 2000. Linking processes at various scales to their corresponding forcing factors (e.g.…”

Section: Discussionmentioning

confidence: 99%

Estimating scale-dependency in disturbance impacts: El Ni�os and giant kelp forests in the northeast Pacific

2004

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Recent discussions on scaling issues in ecology have emphasized that processes acting at a wide range of spatial and temporal scales influence ecosystems and thus there is no appropriate single scale at which ecological processes should be studied. This may be particularly true for environmental disturbances (e.g. El Niño) that occur over large geographic areas and encompass a wide range of scales relevant to ecosystem function. However, it may be possible to identify the scale(s) at which ecosystems are most strongly impacted by disturbances, and thus provide a measure by which their impacts can be most clearly described, by assessing scale-dependent changes in the patterns of variability in species abundance and distribution. This, in turn, may yield significant insight into the relative importance of the various forcing factors responsible for generating these impacts. The 1997-98 El Niño was one of the strongest El Niños ever recorded. I examined how this event impacted giant kelp populations in the northeast Pacific Ocean at 90 sites ranging from central Baja California, Mexico to central California, USA. These sites spanned the geographic range of giant kelp in the Northeast Pacific and were surveyed just before, immediately following, several months after, more than 1 year after, and nearly 2 years after the El Niño. I used a hierarchical sample design to compare these impacts at five spatial scales spanning six orders of magnitude, from a few meters to more than 1,000 km. Variance Components Analyses revealed that the El Niño shifted control over giant kelp abundance from factors acting at the scale of a few meters (local control) to factors operating over hundreds to thousands of kilometers (regional control). Moreover, El Niño resulted in the near-complete loss of all giant kelp throughout one-half of the species' range in the northeast Pacific Ocean. Giant kelp recovery following El Niño was far more complex and variable at multiple spatial scales, presumably driven by numerous factors acting at those scales. Recovery returned local control of giant kelp populations within 6 months in southern California, and within 2 years in Baja California.

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Section: Discussionmentioning

confidence: 99%

Estimating scale-dependency in disturbance impacts: El Ni�os and giant kelp forests in the northeast Pacific

2004

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“…According to our molecular hypothesis (Fig. 3), the European, Asian, and American species have complicated interre- Berg, 1948b;Vlasenko et al, 1989a A. nudiventris Black, Azov, Caspian, and Aral 1 seas Berg, 1948b;Sokolov and Vasil'ev, 1989a A. persicus Caspian and Black seas Berg, 1948b;Vlasenko et al, 1989b A. stellatus Caspian, Azov, Black, and Aegean 2 seas Berg, 1948b;Shubina et al, 1989 Huso huso Adriatic, 3 Black, Azov, and Caspian seas Berg, 1948b;Pirogovskii et al, 1989 1 Acipenser nudiventris is extinct now in the Aral Sea region because of drying of this sea (Salikhov and Kamilov, 1995;Zholdasova, 1997). 2 Acipenser stellatus is practically extinct in the Aegean Sea: there were no reports on it in this sea since the 1970s (Papakonstantinou, 1988).…”

Section: Figmentioning

confidence: 96%

Molecular Phylogeny of Acipenserinae

Birstein

DeSalle

1998

Molecular Phylogenetics and Evolution

183

112

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“…This species may reach over 2 m in total length, although they are more commonly found to be about 1 m in length (Shubina et al 1989). Pseudoscaphirhynchus kauffmani (Bogdanov 1874), the large Amu-Dar shovelnose sturgeon, is endemic to the Amu-Darya River and its tributaries (Birstein 1997) and has been a victim of the drying of the Aral Sea (Zholdasova 1997). There are two forms of P. kaufmanni, a dark colored dwarf form and a light colored normal form (Salnikov et al 1996); the forms also differ in position of fins (Birstein 1997).…”

Section: Introductionmentioning

confidence: 97%

Observations on the skulls of sturgeons (Acipenseridae): shared similarities of Pseudoscaphirhynchus kaufmanni and juvenile specimens of Acipenser stellatus

Hilton

2005

Environ Biol Fish

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A novel hypothesis uniting Acipenser stellatus and Pseudoscaphirhynchus as sister groups has recently been proposed based on analysis of DNA sequences. In this paper I compare specimens of A. stellatus and P. kaufmanni, and show that they share several putatively derived similarities in the structure of their skulls, including: the presence of large spines on the dermal bones of skull; lateral extrascapular bones that enclose the confluence of the posttemporal, supratemporal, and otic sensory canals; elongate dorsal rostral bones; border rostral bones distinct in shape from dorsal rostral bones; greatly enlarged jugal that lacks a median flange; rostral canal bones that loop posteriorly at the anterior commissure of the rostral sensory canals; and the presence of an elongate, flat, and broad posterior ventral rostral bone. These similarities support a close relationship between A. stellatus and Pseudoscaphirhynchus, but still remain to be critically tested.

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Sturgeons and the Aral Sea ecological catastrophe

Cited by 15 publications

References 2 publications

Estimating scale-dependency in disturbance impacts: El Ni�os and giant kelp forests in the northeast Pacific

Estimating scale-dependency in disturbance impacts: El Ni�os and giant kelp forests in the northeast Pacific

Molecular Phylogeny of Acipenserinae

Observations on the skulls of sturgeons (Acipenseridae): shared similarities of Pseudoscaphirhynchus kaufmanni and juvenile specimens of Acipenser stellatus

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