Neritina granosa 

Scope:Global
Status_ne_offStatus_dd_offStatus_lc_offStatus_nt_offStatus_vu_onStatus_en_offStatus_cr_offStatus_ew_offStatus_ex_off

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Gastropoda Cycloneritimorpha Neritidae

Scientific Name: Neritina granosa
Species Authority: Sowerby, 1825
Taxonomic Source(s): Johnson, P.D., Bogan, A.E., Brown, K.M., Burkhead, N.M., Cordeiro, J.R., Garner, J.T., Hartfield, P.D., Lepitzki, D.A.W., Mackie, G.L., Pip, E., Tarpley, T.A., Tiemann, J.S., Whelan, N.V. and Strong, E.E. 2013. Conservation Status of Freshwater Gastropods of Canada and the United States. Fisheries 38(6): 247-282.

Assessment Information [top]

Red List Category & Criteria: Vulnerable B1ab(ii,iii,iv) ver 3.1
Year Published: 2012
Date Assessed: 2012-03-05
Assessor(s): Cordeiro, J. & Perez, K.
Reviewer(s): Bohm, M., Collen, B. & Seddon, M.
Contributor(s): Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S., Duncan, C. & Richman, N.
Justification:
Neritina granosa has been assessed as Vulnerable under criterion B1ab(i,ii,iii,iv) due to its restricted distribution. It has an estimated extent of occurrence of less than 20,000 km2, a severely fragmented distribution, is unlikely to occur in more than ten locations (based on current knowledge of stream occupancy) and shows a decline in habitat quality, number of locations, and AOO. It is extirpated from some islands. If it were possible to estimate population declines (or use a proxy), then this species may qualify for a higher threat category.

Geographic Range [top]

Range Description:This species is found in high quality streams on four Hawaiian islands. It was historically on all the islands of Kaui, Maui, Molokai, Hawaii and Oahu, restricted to high-quality streams (Hawaii Biological Survey 2010). It is likely now to be present in around six to ten locations, based on known stream occurrences (see population section), and is only confirmed from four of the Hawaiian islands, Maui, Hawaii, Kaui, and Oahu (Hodges 1992, Hodges and Allendorf 1998, Fitzsimons et al. 2005, Hau 2007, Hawaii Watershed Atlas 2008, Kido 2008, Hawaii Biological Survey 2010). Its estimated extent of occurrence is less than 20,000 km2.
Countries occurrence:
Native:
United States (Hawaiian Is.)
Additional data:
Number of Locations:5-10Continuing decline in number of locations:Yes
Upper elevation limit (metres):400
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species was formerly common in Hawaii, but has declined throughout its range and is now present in only a few relatively pristine streams (Brooks 2009).

Maui: Hodges (1992) and Hodges and Allendorf (1998) reported populations ranging from 70,000 to 350,000 individuals in three streams on Maui and many other stream populations probably were of a similar size, although some may have been larger. Monthly counts were from 576 in ├Ćao Stream (1999-2004) while Honoman├╝ Stream counts were from 67912 (Hau 2007). Known number of locations is at least three (three streams), but may be more.

Hawaii: Recent surveys on Kawainui stream, Hawaii island, found this species in densities of 9.5 ind m-2 in the middle part of the stream (Hawaii Watershed Atlas 2008). Known number of locations is at least one (Kawainui stream), but may be more.

Kaui: In a stream on Kaui, this species extended from the stream mouth to 259 m asl (although it has been recorded up to 400 m asl), being most abundant in the lower stretch. Densities ranged from 0.01 to 0.02 ind. per sq. m (Kido 2008). Known number of locations is at least one (one stream on Kaui), but may be more.

Oahu: Here, the species is uncommon (Hawaii Biological Survey 2010). A recent survey on a stream in Oahu recorded only two individuals (Fitzsimons et al. 2005). Known number of locations is at least one (one stream on Oahu).
Current Population Trend:Decreasing
Additional data:
Population severely fragmented:Yes

Habitat and Ecology [top]

Habitat and Ecology:This amphidromous species (migrates between salt and freshwater for reproduction) inhabits relatively pristine, fast-flowing streams with boulders and gravel substrates (Hawaii Biological Survey 2010). Adults feed on algae in the benthic zone (Brooks 2009). It may also occur under waterfalls (Pyron and Covich 2003).
Systems:Freshwater; Marine
Continuing decline in area, extent and/or quality of habitat:Yes

Use and Trade [top]

Use and Trade: This large snail is an important food item for Native Hawaiians (Hodges and Allendorf 1998).

Threats [top]

Major Threat(s): A variety of threats have caused past declines in this species. These include: impoundment; water diversion and changes in stream flow; urbanisation; and habitat alteration or shading brought about by non-native riparian vegetation (Brooks 2009). Further threats that may impact this species include siltation via erosion of disturbed watersheds, direct or indirect pollution of surface or groundwater, and introduction of invasive species that may predate on or compete with native species (Gon III 2006).

Impediments to natural flow and saline water encroachment are the greatest threats, however natural flow restoration is possible (Hau 2007). Such diversions in Iao and Honomanu Streams on the island of Maui have reduced stream flow, and with it the reproductive success of this species (Hau 2007). This means the snails are unable to complete their migration upstream and are restricted to estuaries, where they are vulnerable to tidal action and desiccation (Hau 2007). They are limited in their upstream migration by low stream flows and instream obstructions (HI NHP pers. comm. 2008).

Amphidromous species are also vulnerable to deterioration in more than one habitat, such as freshwater, estuaries and the open sea (Hodges and Allendorf 1998). Reduced stream quality on Oahu island has meant that populations there have declined (Hawaii Biological Survey 2010). This large snail is also an important food item for Native Hawaiians (Hodges and Allendorf 1998). Flooding also results in overflowing sewage plants entering streams (Goodwin 2006).

Extensive flooding - resulting in high sedimentation, turbidity, nutrients, trash and other pollutants emptying into streams, rivers, estuaries, and oceans is also a major threat. The recent flooding event caused wastewater treatment plants to overflow - causing hundreds of thousands of gallons of raw and untreated sewage to enter streams inhabited by this species (Goodwin 2006).

Conservation Actions [top]

Conservation Actions: This species has a Global Heritage Status of G1 - Critically Imperiled (NatureServe 2009). Few populations are protected, although restocking efforts are underway in some parts of its range (Goodwin 2006).

Surveys to establish population size, distribution and trends on all islands in the Hawaiian Archipelago are recommended. Stream restoration, management and protection are vital to ensure continued viability of most populations of this species.

Classifications [top]

5. Wetlands (inland) -> 5.1. Wetlands (inland) - Permanent Rivers/Streams/Creeks (includes waterfalls)
suitability: Suitable  major importance:Yes
9. Marine Neritic -> 9.10. Marine Neritic - Estuaries
suitability: Suitable  major importance:Yes
2. Land/water management -> 2.1. Site/area management
2. Land/water management -> 2.3. Habitat & natural process restoration
3. Species management -> 3.2. Species recovery
5. Law & policy -> 5.1. Legislation -> 5.1.2. National level

In-Place Research, Monitoring and Planning
In-Place Land/Water Protection and Management
In-Place Species Management
  Successfully reintroduced or introduced beningly:Yes
In-Place Education
5. Biological resource use -> 5.4. Fishing & harvesting aquatic resources -> 5.4.1. Intentional use: (subsistence/small scale)
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

7. Natural system modifications -> 7.2. Dams & water management/use -> 7.2.4. Abstraction of surface water (unknown use)
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

7. Natural system modifications -> 7.2. Dams & water management/use -> 7.2.8. Abstraction of ground water (unknown use)
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

7. Natural system modifications -> 7.3. Other ecosystem modifications
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive & other problematic species & genes -> 8.1. Invasive non-native/alien species -> 8.1.1. Unspecified species
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

9. Pollution -> 9.1. Domestic & urban waste water -> 9.1.3. Type Unknown/Unrecorded
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

9. Pollution -> 9.3. Agricultural & forestry effluents -> 9.3.2. Soil erosion, sedimentation
♦ timing: Ongoing ♦ scope: Unknown ♦ severity: Unknown ⇒ Impact score: Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

1. Research -> 1.2. Population size, distribution & trends

♦  Food - human
 National : ✓ 

Bibliography [top]

Brooks, S. 2009. Effects of non-native riparian vegetation on hihiwai (Neritina granosa) ecology in Honoli'i stream, Hawaii. Hilo, Hawaii, US.

Fitzsimons, Y.M., Parham, Y.E., Benson, L.K., McRae, M.G. and Nishimoto, R.T. 2005. Biological assessment of Kahana stream, island of O'ahu, Hawai'i: an application of PABITRA survey methods. Pacific Science 59(2): 273-281.

Gon. III. S.M. 2006. Hawaiian continuous perennial streams. Available at: http://www.hawaiiecoregionplan.info/home.html.

Goodwin, D.R. 2006. The discovery of Neritina (theodoxus) cariosa (Wood, 1928) on the island of Maui, Hawaii (Gastropoda: eritidae). Visaya Net.

Hau, S. 2007. Hihiwai ( Neritina granosa Sowerby) Recruitment in Iao and Honomanu streams on the island of Maui, Hawai'i. Biology of Hawaiian Streams and Estuaries 3: 171-181.

Hawaii Biological Survey. 2010. Neritina granosa . Available at: http://hbs.bishopmuseum.org/waipio/index.html.

Hawaii Watershed Atlas. 2008. Atlas of Hawaiian watersheds and their aquatic resources.

Hodges, M.H. 1992. Population biology and genetics of the endemic Hawaiian stream gastropod Neritina granosa (Prosobranchia: Neritidae): implications for conservation. MS Thesis, University of Montana.

Hodges, M.H. and Allendorf, F.W. 1998. Population genetics and pattern of larval dispersal of the endemic Hawaiian freshwater amphidromous gastropod Neritina granosa (Prosobranchia: Neritidae). Pacific Science 52(3): 237-249.

IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1). Available at: http://www.iucnredlist.org. (Accessed: 19 June 2012).

Kido, M.H. 2008. A persistent species assemblage structure along a Hawaiian stream from catchment-to-sea. Environmental Biology of Fishes 82: 223-235.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. Internet

Pyron, M. and Covich, A.P. 2003. Migration patterns, densities, and growth of Neritina punctulata snails in Rio Espiritu Sato and Rio Mameyes, Northeastern Puerto Rico. Caribbean Journal of Science 39(3): 338-347.


Citation: Cordeiro, J. & Perez, K. 2012. Neritina granosa. In: The IUCN Red List of Threatened Species 2012: e.T189675A1932107. . Downloaded on 23 July 2016.
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