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Invasive rats on tropical islands: their population biology and impacts on native species
BRB
Available Online

Bunbury, Nancy

,

Harper, Grant. A,

2015
The three most invasive rat species, black or ship rat Rattus rattus, brown or Norway rats, R. norvegicus and Pacific rat, R. exulans have been incrementally introduced to islands as humans have explored the world’s oceans. They have caused serious deleterious effects through predation and competition, and extinction of many species on tropical islands, many of which are biodiversity hotspots. All three rat species are found in virtually all habitat types, including mangrove and arid shrub land. Black rats tend to dominate the literature but despite this the population biology of invasive rats, particularly Norway rats, is poorly researched on tropical islands. Pacific rats can often exceed population densities of well over 100 rats ha?1 and black rats can attain densities of 119 rats ha?1, which is much higher than recorded on most temperate islands. High densities are possibly due to high recruitment of young although the data to support this are limited. The generally aseasonally warm climate can lead to year-round breeding but can be restricted by either density-dependent effects interacting with resource constraints often due to aridity. Apparent adverse impacts on birds have been well recorded and almost all tropical seabirds and land birds can be affected by rats. On the Pacific islands, black rats have added to declines and extinctions of land birds caused initially by Pacific rats. Rats have likely caused unrecorded extinctions of native species on tropical islands. Further research required on invasive rats on tropical islands includes the drivers of population growth and carrying capacities that result in high densities and how these differ to temperate islands, habitat use of rats in tropical vegetation types and interactions with other tropical species, particularly the reptiles and invertebrates, including crustaceans.
Lime juice and vinegar injections as a cheap and natural alternative to control COTS outbreaks
BRB
Available Online

Moutardler, Gregoire ... et al.

2015
Outbreaks of the corallivorous crown-of-thorns seastar Acanthaster planci (COTS) represent one of the greatest disturbances to coral reef ecosystems in the Indo-Pacific, affecting not only coral reefs but also the coastal communities which rely on their resources. While injection approaches are increasingly used in an attempt to control COTS densities, most of them display severe drawbacks including logistical challenges, high residual environmental impacts or low cost-effectiveness. We tested a new alternative control method based upon acidic injections of cheap, 100% natural products. We investigated the lethal doses, intraand inter-specific disease transmission and immune responses of COTS when injected with fresh lime juice (extracted from local Citrus arantifolia) and white spirit vinegar. High COTS mortality was achieved with small volumes: 10–20 ml per seastar induced death in 89%/ 97% of injected specimens after an average 34.3 h/29.8 h for lime juice and vinegar respectively. Highest efficiency was reached for both solutions with double shots of (2 × 10 ml) in two different areas on the body: 100% mortality occurred within 12–24 h, which is similar or faster compared with other current injection methods. Multiple immune measures suggested that death was very likely caused by pH stress from the acidic solutions rather than a bacterial infection. Contagion to either conspecifics or a variety of other reef species was not observed, even at COTS densities 15 times higher than the highest naturally reported. 10 to 20 l lime juice/vinegar could kill up to a thousand COTS at a cost of less than 0.05 USD per specimen; no permits or special handling procedures are required. We conclude that injections of lime juice and vinegar offer great advantages when compared to current best practises and constitute a cheap and natural option for all reefs affected by COTS
Taking the sting out of the Little Fire Ant in Hawaii
BRB

Lee, Donna J.

,

Leung, PingSun

,

Motoki, Michael

,

Nakamoto, Stuart T.

,

Vanderwoude, Casper

2015
Inthe1990's,LittleFireAnts(LFAs)founditswaytotheislandofHawaii,mostlikelytravelingwithashipmentof potted plantsfrom Florida.These plants weresubsequentlysold toconsumers along theeastcoast of theIsland, alongwithLittleFireAntcolonieslivinginthepottingmedium.LFAisnowthrivingandcontinuestospread.Fifteenyearsaftertheinitialdetectionin1999,LFAhasspreadtoover4000locationsontheislandofHawaiiandhas beenfoundinisolatedlocationsonKauai,Maui,andOahuIslands.Currenteffortsareexpectedtocontaintheinfestations on the otherislands but signi cant additional investment isneeded tohalt therapid spread of LFA on the island of Hawaii. Increased management expenditures can suppress infestations; reduce spread between sectors; and decrease long-term management costs, damages, and stings.| Animmediateexpenditureof$8millioninthenext2–3yearsplusfollow-upprevention,monitoring,andmitigation treatments will yield $1.210 billion in reduced control costs, $129 million in lowered economic damages, 315 million fewer human sting incidents, and 102 million less pet sting incidents over 10 years.| Over35years,thebene tsinclude$5.496billioninreducedcontrolcosts,$538millionlesseconomicdamages, 2.161 billion fewer human sting incidents, and 762 million fewer pet sting incidents.