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Hemiboeckella powellensis

Hemiboeckella powellensis, is a zooplankton copepod of which only four of its kind have ever been observed. "Hemiboeckella" refers to this genus being a subvariant of Boeckella,[3] whilst “powellensis” refers to Lake Powell in Western Australia, the region it is endemic to. Its existence was initially recorded in May and June 1977, and has not been observed since.[4]

Hemiboeckella powellensis
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Subphylum:
Crustacea
Class:
Maxillopoda
Subclass:
Copepoda
Order:
Calanoida
Family:
Centropagidae
Genus:
Hemiboeckella
Species:
H. powellensis
Binomial name
Hemiboeckella powellensis
Bayly, 1979 [2]

Description

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Hemiboeckella powellensis is a small crustacean that ranges from 0.67 to 1.16mm.[5] Like all crustaceans, it has a segmented exoskeleton. It also has a copepod's characteristically round shaped body. The head consists of two setae on the anterior face, along with segmented maxillipeds. Protruding from its anterior, there are two antennae that are longer than its abdomen, with another smaller antennule.[6] It has nautical eye, a characteristic trait of copepods.[7] However, it does not appear to be used as a visual aid. It has four legs that are segmented three times, along with a curved claw on its right side near its head, and a much shorter exopodite limb on its left. Said claw contains small spines on the inside, a trait shared with species such as Karukinka fueguina and Hemiboeckella searli.[8] The rear end (urosome) is slimmer than its body, a trait consistent with most copepods.[9]

Since there have been no observed females, the sex differences are unknown. However, it is a defining trait of species within the Hemiboeckella genus to have significant differences between the genders.[10]

Habitat and distribution

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H.powellensis has only ever been observed in Lake Powell,[11] which is a 4 km^2 estuary near Albany, and is a part of the Torbay Lake system, which in turn is part of the Warren bioregion.[12] In particular, this species was observed in vegetation near the lake’s shore.[13] Being part of a lake system, the species habitat is subjected to water flows from nearby creeks, as well as freshwater runoff from other local estuaries.[14] The water level is generally quite shallow, due to a high sediment buildup. Said sediments are a mixture of sand, silt and nutrient dense soils, caused by runoff from nearby estuary drains. The water is somewhat acidic, unsalty and of moderate temperatures.[15] Whilst the lake is considered stagnant freshwater, due to the presence of marine copepod Gladioferens imparipes, and the lake's proximity to the ocean, it can be inferred that there is some tidal influence over the region.[16]

Prior to human intervention, Lake Powell would dry up in the summer. However, due to nearby residents concerned with flooding, creeks and other estuaries flowing into Lake Powell would be blocked, and water would be let in manually. Due to this, the Lake no longer dries up during the summer. The effect that this has had on H.Powellensis is unknown.[17]

Origins

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In general, Western Australia, particularly southern Western Australia, is home to a lot of endemic copepods similar to H.powellensis. It is theorised that this occurred when water levels started to recede during the Cretaceous period, leaving behind estuaries filled with unique copepod species.[18]

Behaviour and adaptations

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Not much has been directly observed on the behaviour of H.powellensis. However, its physical attributes indicate some of its behavioural tendencies.

Feeding

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As a freshwater zooplankton that is a part of the calanoida order, H.powellensis most likely feeds on the abundant phytoplankton present in Lake Powell.[19] The maxillipeds move around in the water to produce a current, leading to prey flowing towards H.powellensis. Its remaining limbs grasp its prey to be placed into its body for digestion.[20] Some of its potential prey include Nodularia spumigena, Anabaena circinalis and Microcystis aeruginosa, since they are very abundant in Lake Powell.[21] The right-side claw can also be used to obtain resources.[22]

Reproduction

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Genital segments have also been observed on the species, indicating the ability to sexually reproduce.[23] Other attributes such as the mechanism of reproduction, fertilisation and the species lifecycle have yet to be observed.

Adaptations

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The antennules on its face are typically used to find members of its species, or to locate and avoid predators. H.powellensis most likely utilises four of its legs for swimming, a trait consistent with other calanoida order copepods.[24]

Conservation status

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Due to H.powellensis being endemic to such a precise region,[25] the IUCN Red List of Endangered Species lists it as “vulnerable”. The niche distribution of the species means that if Lake Powell is threatened, then the species could be in serious danger of extinction.[26]

Erosion, salinisation and urbanisation due to European settlement may all pose a risk to their habitat. An increase in human activity has led to acid-sulphate soils to run into the lake, which led to the water increasing in acidity, and therefore damaging the organism populations in the lake.[27] As well as this, the three creeks supplying water into Lake Powell have their water flows artificially controlled by human interference, which has permanently altered the composition of the lake.[28] As a result, cyanobacteria and typhus blooms[29] have both been documented in the area. The poor water quality of the lake is of concern, but stakeholders have been making efforts to improve H.powellensis's habitat.[30]

In 1977, attempts to collect more specimens on H.powellesis were made by collecting samples from Lake Powell and nearby estuaries, but none were found.[31]

Similar species

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Hemiboeckella powellensis is one of three different species found in the Hemiboeckella genus. The other two, Hemiboeckella searli and Hemiboeckella andersonae, are also endemic to Australia.[32] The three species are all very similar, but can be differentiated by claw size, limb length and number of exoskeleton segments. Unlike H.powellensis, both H.searli and H.andersonae are distributed throughout the eastern and western coasts of Australia.[33]

Hemiboeckella was named after the genus Boeckella due to both species being very similar. Due to this, there has been debate as to whether these two genera should be considered unique to one another,[34] or if Hemiboeckella is a subgenus of Boeckella.[35]

H.powellensis also retains a lot of similarities to most species of calanoida copepods, particularly between species located in Australia and New Zealand. This could be due to both continents being a part of the supercontinent Gondwana. Once this continent separated due to continental drift, the copepod species became more geographically isolated.

References

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  1. ^ Reid, J.W. (1996). "Hemiboeckella powellensis". IUCN Red List of Threatened Species. 1996: e.T9870A13023265. doi:10.2305/IUCN.UK.1996.RLTS.T9870A13023265.en. Retrieved 6 October 2021.
  2. ^ T. Chad Walter (2010). Walter TC, Boxshall G (eds.). "Hemiboeckella powellensis Bayly, 1979". World of Copepods database. World Register of Marine Species. Retrieved June 28, 2012.
  3. ^ Bayly, I.A.E. (1974). A NEW SPECIES OF HEMIBOECKELLA (FRESHWATER COPEPODA CALANOIDA) FROM WESTERN AUSTRALIA. Museum of Western Australia, [online] 3(2). Available at: https://museum.wa.gov.au/sites/default/files/A%20NEW%20SPECIES%20OF%20HEMIBOECKELLA%20(FRESHWATER%20COPEPODA%20CALANOIDA)%20FROM%20WESTERN%20AUSTRALIA.pdf [Accessed 4 Apr. 2022].
  4. ^ Bayly, I. (1979). Further Contributions to a Knowledge of the Centropagid Genera Boeckella, Hemiboeckella and Calamoecia (Athalassic Calanoid Copepods). Marine And Freshwater Research, 30(1), 103. https://doi.org/10.1071/mf9790103
  5. ^ Bayly, I. (1979). Further Contributions to a Knowledge of the Centropagid Genera Boeckella, Hemiboeckella and Calamoecia (Athalassic Calanoid Copepods). Marine And Freshwater Research, 30(1), 103. https://doi.org/10.1071/mf9790103
  6. ^ Bayly, I.A.E. (1974). A NEW SPECIES OF HEMIBOECKELLA (FRESHWATER COPEPODA CALANOIDA) FROM WESTERN AUSTRALIA. Museum of Western Australia, [online] 3(2). Available at: https://museum.wa.gov.au/sites/default/files/A%20NEW%20SPECIES%20OF%20HEMIBOECKELLA%20(FRESHWATER%20COPEPODA%20CALANOIDA)%20FROM%20WESTERN%20AUSTRALIA.pdf [Accessed 4 Apr. 2022]
  7. ^ Bradford-Grieve, J. M. (2013, June 18). Calanoidea: Families - Index. Crustaceans.net; National Institute of Water and Atmospheric Research. https://web.archive.org/web/20130618054223/http://www.crustacea.net/crustace/calanoida/
  8. ^ (Menu-Marque, S. (2002). KARUKINKA FUEGUINA N. GEN., N. SP. (COPEPODA, CALANOIDA, CENTROPAGIDAE) FROM TIERRA DEL FUEGO. Crustaceana, 75(10), 1229–1240. https://doi.org/10.1163/156854002321518162)
  9. ^ Bayly, I. (1979). Further Contributions to a Knowledge of the Centropagid Genera Boeckella, Hemiboeckella and Calamoecia (Athalassic Calanoid Copepods). Marine And Freshwater Research, 30(1), 103. https://doi.org/10.1071/mf9790103
  10. ^ Bayly, I.A.E. (1974). A NEW SPECIES OF HEMIBOECKELLA (FRESHWATER COPEPODA CALANOIDA) FROM WESTERN AUSTRALIA. Museum of Western Australia, [online] 3(2). Available at: https://museum.wa.gov.au/sites/default/files/A%20NEW%20SPECIES%20OF%20HEMIBOECKELLA%20(FRESHWATER%20COPEPODA%20CALANOIDA)%20FROM%20WESTERN%20AUSTRALIA.pdf [Accessed 4 Apr. 2022].
  11. ^ Maly, E., Halse, S., & Maly, M. (1997). Distribution and incidence patterns of Boeckella, Calamoecia, and Hemiboeckella (Copepoda : Calanoida) in Western Australia. Marine And Freshwater Research, 48(7), 615. https://doi.org/10.1071/mf97015
  12. ^ Trayler, K., Davis, J., Horwitz, P., & Morgan, D. (1996). Aquatic fauna of the Warren bioregion, south-west Western Australia: Does reservation guarantee preservation? The Journal Of The Royal Society Of Western Australia, 79. Retrieved 17 March 2022.
  13. ^ Bayly, I. (1979). Further Contributions to a Knowledge of the Centropagid Genera Boeckella, Hemiboeckella and Calamoecia (Athalassic Calanoid Copepods). Marine And Freshwater Research, 30(1), 103. https://doi.org/10.1071/mf9790103
  14. ^ Murray, E., Smith, C., Smith, J., Haese, R. and Heggie, D. (2005). Nutrient Release from Sediments of the Torbay Drainage System, South-Western Australia Record 2005/14 GEOSCIENCE AUSTRALIA. [online] Available at: https://d28rz98at9flks.cloudfront.net/63572/Rec2005_014.pdf [Accessed 14 Apr. 2022].
  15. ^ Adeny, J.A. (2001). Cyanobacterial Issues in the Lake Powell/Torbay Inlet Drainage System. Unpublished CSIRO Land and Water Technical Report, 44(01).
  16. ^ Bayly, I.A.E. (1974). A NEW SPECIES OF HEMIBOECKELLA (FRESHWATER COPEPODA CALANOIDA) FROM WESTERN AUSTRALIA. Museum of Western Australia, [online] 3(2). Available at: https://museum.wa.gov.au/sites/default/files/A%20NEW%20SPECIES%20OF%20HEMIBOECKELLA%20(FRESHWATER%20COPEPODA%20CALANOIDA)%20FROM%20WESTERN%20AUSTRALIA.pdf [Accessed 4 Apr. 2022].
  17. ^ The Torbay Lake System. (n.d.). Torbay Catchment Group; Torbay Catchment Group. Retrieved April 12, 2022, from https://torbaycatchment.org.au/the-torbay-lake-system/
  18. ^ Bayly, I. A. E. (1992). The Microcrustea and Physico-chemical Features of Temporary Ponds near Northcliff, Western Australia. Journal of the Royal Society of Western Australia, 75(1992).
  19. ^ Bradford-Grieve, J. M. (2013, June 18). Calanoidea: Families - Index. Crustaceans.net; National Institute of Water and Atmospheric Research. https://web.archive.org/web/20130618054223/http://www.crustacea.net/crustace/calanoida/
  20. ^ Bradford-Grieve, J. M. (2013, June 18). Calanoidea: Families - Index. Crustaceans.net; National Institute of Water and Atmospheric Research. https://web.archive.org/web/20130618054223/http://www.crustacea.net/crustace/calanoida/
  21. ^ Adeny, J.A. (2001). Cyanobacterial Issues in the Lake Powell/Torbay Inlet Drainage System. Unpublished CSIRO Land and Water Technical Report, 44(01).
  22. ^ Bradford-Grieve, J. M. (2013, June 18). Calanoidea: Families - Index. Crustaceans.net; National Institute of Water and Atmospheric Research. https://web.archive.org/web/20130618054223/http://www.crustacea.net/crustace/calanoida/
  23. ^ Bayly, I.A.E. (1974). A NEW SPECIES OF HEMIBOECKELLA (FRESHWATER COPEPODA CALANOIDA) FROM WESTERN AUSTRALIA. Museum of Western Australia, [online] 3(2). Available at: https://museum.wa.gov.au/sites/default/files/A%20NEW%20SPECIES%20OF%20HEMIBOECKELLA%20(FRESHWATER%20COPEPODA%20CALANOIDA)%20FROM%20WESTERN%20AUSTRALIA.pdf [Accessed 4 Apr. 2022].
  24. ^ Bradford-Grieve, J. M. (2013, June 18). Calanoidea: Families - Index. Crustaceans.net; National Institute of Water and Atmospheric Research. https://web.archive.org/web/20130618054223/http://www.crustacea.net/crustace/calanoida/
  25. ^ Pennifold, M., 2018. Identifying Priority Species Within the South-western Australian Aquatic Invertebrate Fauna. [online] Library.dbca.wa.gov.au. Available at: <https://library.dbca.wa.gov.au/static/FullTextFiles/072273.pdf> [Accessed 17 March 2022].
  26. ^ Reid, J. (1996). IUCN Red List of Threatened Species: Hemiboeckella powellensis. IUCN Red List of Threatened Species. Retrieved 15 March 2022, from https://www.iucnredlist.org/species/9870/13023265#population.
  27. ^ Adeny, J.A. (2001). Cyanobacterial Issues in the Lake Powell/Torbay Inlet Drainage System. Unpublished CSIRO Land and Water Technical Report, 44(01).
  28. ^ The Torbay Lake System. (n.d.). Torbay Catchment Group; Torbay Catchment Group. Retrieved April 12, 2022, from https://torbaycatchment.org.au/the-torbay-lake-system/
  29. ^ Bourne, M. (2002). Typha orientalis invasion of Lake Powell : causes and consequences. Murdoch University These. [online] Available at: https://prospero.murdoch.edu.au/search~S1?/Xlake+powell&searchscope=1&SORT=D/Xlake+powell&searchscope=1&SORT=D&SUBKEY=lake+powell/1%2C13%2C13%2CB/frameset&FF=Xlake+powell&searchscope=1&SORT=D&1%2C1%2C [Accessed Apr. 2022].
  30. ^ Murray, E., Smith, C., Smith, J., Haese, R. and Heggie, D. (2005). Nutrient Release from Sediments of the Torbay Drainage System, South-Western Australia Record 2005/14 GEOSCIENCE AUSTRALIA. [online] Available at: https://d28rz98at9flks.cloudfront.net/63572/Rec2005_014.pdf [Accessed 14 Apr. 2022].
  31. ^ Bayly, I. (1979). Further Contributions to a Knowledge of the Centropagid Genera Boeckella, Hemiboeckella and Calamoecia (Athalassic Calanoid Copepods). Marine And Freshwater Research, 30(1), 103. https://doi.org/10.1071/mf9790103
  32. ^ Bayly, I.A.E. (1974). A NEW SPECIES OF HEMIBOECKELLA (FRESHWATER COPEPODA CALANOIDA) FROM WESTERN AUSTRALIA. Museum of Western Australia, [online] 3(2). Available at: https://museum.wa.gov.au/sites/default/files/A%20NEW%20SPECIES%20OF%20HEMIBOECKELLA%20(FRESHWATER%20COPEPODA%20CALANOIDA)%20FROM%20WESTERN%20AUSTRALIA.pdf [Accessed 4 Apr. 2022].
  33. ^ Bayly, I. (1979). Further Contributions to a Knowledge of the Centropagid Genera Boeckella, Hemiboeckella and Calamoecia (Athalassic Calanoid Copepods). Marine And Freshwater Research, 30(1), 103. https://doi.org/10.1071/mf9790103
  34. ^ C D Marsh. (1924). A synopsis of the species of Boeckella and Pseudoboeckella with a key to the genera of the fresh-water Centropagidae. In Internet Archive. US National Museum. https://archive.org/stream/biostor-79668/biostor-79668_djvu.txt
  35. ^ Bayly, I. (1964). A revision of the Australasian species of the freshwater genera Boeckella and Hemiboeckella (Copepoda: Calanoida). Marine and Freshwater Research, 15(2), 180. https://doi.org/10.1071/mf9640180
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