The end of an 80-million year experiment: a review of evidence describing the impact of introduced rodents on New Zealand’s ‘mammal-free’ invertebrate fauna

Since separating from its super-continental origin 80 million years ago, New Zealand has effectively been isolated from the impacts of terrestrial mammals. The arrival of Polynesians in 13th C heralded the end of this era, with the introduction of kiore, (Rattus exulans, or Pacific rat), which had far-reaching effects on plant regeneration, survival of small ground vertebrates, larger invertebrates, and seabird breeding colonies. This paper reviews the evidence available from raptor nest sites and Quaternary beetle fossils to summarise extinctions thought to be caused by kiore in New Zealand. It also utilises invertebrate comparisons between islands with and without rats, or where rats have been eradicated, in order to document the impacts of rats (R. exulans, R. norvegicus) on invertebrate abundance, body mass, and the behavioural responses of some large New Zealand insects to the presence of rats. The role of a ‘mammal-free’ evolutionary history is discussed.     

Rapid community change at a tropical upwelling site in the Galápagos Marine Reserve

The high biodiversity of tropical marine communities has attractedconsiderable interest, yet we still lack a clear understanding of the tempo ofdiversity change in these systems []. Knowledge of the conditions associated with fast or slow community assembly inthe tropics would enhance our ability to predict recovery from natural andanthropogenic disturbance and to conserve biodiversity. Here we report anunusually rapid doubling of species richness within a year in a tropical,subtidal sessile invertebrate community in a protected (non-extractive) zone ofthe Galápagos Marine Reserve (GMR). Diversity changes in the rock wallcommunity were accompanied by large increases in the percent cover, densityand/or biomass of sponges, barnacles, ascidians, and an ahermatypic coral,Tubastrea coccinea, over the 1-year studyperiod (1999–2000). Barnacle (Megabalanuspeninsularis) and ascidian (Didemnum cineraceum)biomasses increased by an order of magnitude from 1999 to 2000. The greaterabundance of sessile invertebrate prey was accompanied by significant increasesin the abundance of barnacle and Tubastrea predators(Hexaplex princeps, Asperiscalabilleeana). An estimated 37% of barnacle tissue biomass productionwas consumed in 1 year. Temperature monitoring during the studyperiod showed that this site is characterized by strong upwelling, where rapid,3.0–9.0 °C decreases in temperature occurred at harmonicsof the semi-diurnal tidal periodicity during warm (January–February), butnot during cool months (June–July). Short-term acoustic current metermeasurements revealed strong, highly variable upwelling at the study site, withevents ranging from 2–111 min in duration and maximumupwelling velocities of 32.3 cm s^–1. Thesefindings suggest that the turnover of diversity and biomass may be unusuallyrapid at tropical upwelling sites, especially where invertebrate predators areprotected from harvesting. Consequently, upwelling sites may warrant specialconsideration in the planning of marine reserves to ensure the conservation ofbiodiversity.     

A new species of Erebonectes (Copepoda,Calanoida) from marine caves on Caicos Islands,West Indies

The insects of a small and cold aestival stream in northern Sweden were studied from semiquantitative kick-samples taken every ten days throughout the ice-free season in 1987. The stream froze solid at least in some sections in some winters. In addition to dipterans that were only identified to the family level, five ephemeropteran, four plecopteran, 11 coleopteran (Dytiscidae), and four trichopteran (Limnephilidae) species were found. Baetis bundyae Lemkuhl, Heptagenia orbiticola Kluge (Ephemeroptera), Nemoura cinerea (Retzius) (Plecoptera), Hydroporus palustris (L), Agabus setulosus (J. Sahlberg) (Coleoptera), Anabolia concentrica (Zetterstedt), Limnephilus coenosus Curtis, and Micopterna sequax McLachlan (Trichoptera) were all common. Malaise trap data are given for Plecoptera. The two ephemeropteran species Heptagenia orbiticola and Metretopus alter Bengtsson, and the plecopteran species Nemoura viki Lillehammer were recorded for the first time in Sweden. The remarkable species composition was attributed to the harsh abiotic and poorly studied environment. We predicted that the larval composition of this stream was representative for aestival streams in northernmost Fennoscandia.     

Denitrification in Bahia Darwin (Galapagos Islands) an intermittent anoxic basin in the tropics

Changes in oxygen and nitrate in Bahia Darwin between July 1968 and March 1969 indicate that denitrification occurred in the deeper waters of this tropical, intermittently anoxic basin. Assuming constant rates of oxidation of organic matter in equally spaced depth intervals below the pycnocline depth, the rate of denitrification was estimated to be about 62.0 µg-atom NO₃-N/liter/year. This rate is attributable to denitrification in the water column because a smaller rate was estimated for strata closer to the sediment water interface.Contribution No. 3193 from the Woods Hole Oceanographic Institution. Woods Hole, Massachusetts 02543. This study was supported in part by the National Science Foundation Grants GA 29303 and GB 6870. Reprints should be requested from the second author.     

Moth hearing on the Faeroe Islands, an area without bats

ABSTRACT. The ultrasound-sensitive ears found in several families of moths are believed to be part of a predator (bat) specific defence strategy; the moth's evasive responses, elicited by the calls of bats, reduce its chances of being caught. Bats have never been found on the Faeroe Islands, whereas moths migrated there before the last Ice Age, and have since been isolated from areas with bats. For this reason, the hearing characteristics of moths from the Faeroes are investigated in this study. All noctuid moths caught there have functional ears sensitive to ultrasound. Audiograms are determined for thirty-two individuals of four noctuid species: Cerapteryx gramminis L., Apamea crenata Hūfn., Apamea maillardi Gey. and Diarsia mendica F. The auditory characteristics of the moths from the Faeroes resemble those of moths from other temperate zones where bats are abundant. The audiograms revealed best frequencies between 20 and 45 kHz, relatively broad turnings (Q_10dB around 1), and thresholds of 35–50 dB SPL at the best frequency. The fact that the moths on the Faeroes possess such sensitive ears is explained by the large time spans which might be required for reduction of a character which is not directly opposed by a selection pressure.     

Hawaii: an ideal model for international aerobiological research

Future aerobiological studies important to mankind's understanding of our planet must demonstrate the ecological interrelationships between the aerial biota of island ecosystems and meteorological, chemical, physical and geographic factors. For example, air quality as related to human health and plant pathology can be more easily ascertained using oceanic islands such as Hawaii with the establishment of an international interdisciplinary aerobiological research team. This revised version was published online in June 2006 with corrections to the Cover Date.