Range extensions in anemonefishes and host sea anemones in eastern Australia: potential constraints to tropicalisation

2017 ◽  
Vol 68 (7) ◽  
pp. 1224 ◽  
Author(s):  
Hamish Malcolm ◽  
Anna Scott
Keyword(s):  
Seawater Temperature ◽  
Eastern Coast ◽  
Sea Anemones ◽  
Rocky Reefs ◽  
Factors Influencing ◽  
Eastern Australia ◽  
Usage Patterns ◽  
Distribution Limits ◽  
Host Sea Anemones ◽  
Entacmaea Quadricolor

Species distributions at range edges show complex shifts with climate change. The present study examined anemonefish and host sea anemone abundance at their southern distribution limits on the eastern coast of Australia, to identify factors influencing the geographic responses of the symbiosis. Roaming surveys (30min) were conducted at 21 sites (~30.01–30.95°S) on rocky reefs in a tropical–temperate transition zone. Two species of host anemones (Entacmaea quadricolor and Heteractis crispa) and anemonefishes (Amphiprion akindynos and A. latezonatus) were found, along with Dascyllus trimaculatus. Nearly all anemones and anemonefishes (>99.5%) were associated with vegetated islands and rocky islets, and abundance was influenced by seawater temperature. Greater numbers of H. crispa and A. akindynos than E. quadricolor and A. latezonatus were found; however, most A. akindynos were juveniles. H. crispa provided nursery habitat for both fishes, whereas adult fishes utilised only E. quadricolor. A southern range extension was found for E. quadricolor, and overwintering of A. latezonatus had extended poleward since the mid-1990s. The paucity of islands and rocky islets south of our surveys, and host-usage patterns, could constrain future range extensions. These findings showed climate-driven latitudinal shifts are complex and are likely to be variably constrained for different species.

Factors influencing population dynamics in island and mainland populations of the swamp antechinus (Antechinus minimus)

2008 ◽  
Vol 56 (3) ◽  
pp. 187 ◽  
Author(s):  
Michael G. Sale ◽  
Barbara A. Wilson ◽  
John P. Y. Arnould
Keyword(s):  
Island Population ◽  
Nutrient Inputs ◽  
Demographic Differences ◽  
Island Populations ◽  
Juvenile Recruitment ◽  
Factors Influencing ◽  
Eastern Australia ◽  
Demographic Processes ◽  
Island Habitats ◽  
Individual Body

Simultaneously analysing demographic processes of small mammals living in different ecological contexts may help to understand mechanisms that influence the growth and decline of these populations. The size and demography of swamp antechinus (Antechinus minimus) populations located in a coastal mainland habitat and on a small offshore island in south-eastern Australia were investigated. Large demographic differences occurred between the two ecosystems, with the island population density often 100 times greater than that on the mainland. The swamp antechinus in the mainland habitat was influenced by extrinsic climatic forces, with juvenile recruitment, individual body mass and overall population size being affected by rainfall, a factor likely to influence food availability for the species. However, the island population did not appear to be affected by drought to the same degree where allochthonous marine nutrient inputs may have offset any drought-induced reduction in primary production. Significantly greater juvenile recruitment in the island habitats combined with restricted emigration and potentially reduced predation and interspecific competition are likely to be responsible for the high population densities on the island. Although island populations appear robust, future conservation efforts should focus on mainland populations given the genetic deficiencies in the island populations.

scholarly journals The Ecological Importance of Toxicity: Sea Anemones Maintain Toxic Defence When Bleached

Toxins ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 266 ◽  
Author(s):  
Cassie M. Hoepner ◽  
Catherine A. Abbott ◽  
Karen Burke da Silva
Keyword(s):  
Food Source ◽  
Environmental Stressors ◽  
Sea Anemones ◽  
Venomous Animals ◽  
Ecological Importance ◽  
Endosymbiotic Algae ◽  
Entacmaea Quadricolor ◽  
Impacts Of Climate Change

Cnidarians are amongst the most venomous animals on the planet. They are also under significant threat due to the impacts of climate change. Corals and anemones undergo climate-induced bleaching during extreme environmental conditions, where a loss of symbiotic photosynthetic algae (zooxanthellae) causes whitening in colour, loss of internal food supply, and reduction in health, which can ultimately lead to death. What has yet to be determined is whether bleaching causes a reduction in the production or quality of venom. In this study, the sea anemone Entacmaea quadricolor was exposed to long-term light-induced bleaching to examine the effect that bleaching has on venom. Venom quality and quantity, as determined through lethality and haemolysis measures and nematocyst production was highly preserved over the five-month imposed bleaching event. Maintenance of venom and nematocyst production, despite a loss of an internal food source provided by endosymbiotic algae, indicates both the ecological importance of maintaining toxicity and a remarkable resilience that anemones have to major environmental stressors.

Modelling the factors influencing Sambar Deer (Rusa unicolor) occurrence in the wet eucalypt forests of south-eastern Australia

2020 ◽  
Author(s):  
S. Sotorra ◽  
D. Blair ◽  
W. Blanchard ◽  
D. Lindenmayer
Keyword(s):  
National Parks ◽  
Negative Binomial ◽  
Negative Binomial Regression ◽  
South Eastern ◽  
Factors Influencing ◽  
Eastern Australia ◽  
Mountain Ash ◽  
Sambar Deer ◽  
Central Highlands ◽  
South Eastern Australia

Many invasive species have had negative effects on the Australian environment, including the introduced Sambar Deer (Rusa unicolor). However, there is a paucity of information on the factors influencing the fine scale distribution and abundance patterns of Sambar Deer in south-eastern Australia. We present the results of a field survey of Sambar Deer in the Critically Endangered Mountain Ash ( Eucalyptus regnans) forests of the Central Highlands, Victoria. Our key question was: What factors influence detections of Sambar deer (based on scat counts) within the Mountain Ash forests of the Victorian Central Highlands? We surveyed 86 long-term field sites and detected a total of 245 groups of Sambar Deer pellets on 42% of these sites. Negative binomial regression modelling identified three factors associated with the occurrence of deer pellets. We recorded more pellets: (1) in 30 and 80 year old forest that remained unburned in fires that occurred in 2009, (2) on sites within closed National Parks relative to sites in State Forest, and (3) close to streams.

Temporal and spatial differences in the reproductive biology of the sea urchin Arbacia dufresnii

2015 ◽  
Vol 66 (4) ◽  
pp. 329 ◽  
Author(s):  
Lucia Epherra ◽  
Damián G. Gil ◽  
Tamara Rubilar ◽  
Soledad Perez-Gallo ◽  
M. Belén Reartes ◽  
...  
Keyword(s):  
Sea Urchins ◽  
Seasonal Pattern ◽  
Seawater Temperature ◽  
Reproductive Traits ◽  
Wide Distribution ◽  
Eastern Coast ◽  
Spawning Period ◽  
Spatial Differences ◽  
Different Seasons ◽  
Temporal And Spatial

The reproductive cycle of Arbacia dufresnii was studied in two contrasting populations on the eastern coast of Patagonia (Nuevo Gulf and San Jorge Gulf) from January 2008 to August 2010. Sea urchins from San Jorge Gulf had larger test diameter and heavier gonads than did sea urchins from Nuevo Gulf. A. dufresnii showed an annual cycle in both populations, with gametogenesis occurring mainly in the autumn and the winter. An extended spawning period took place during the spring and the summer. Sea urchins from Nuevo Gulf had a strong seasonal pattern of reproduction, with presence of gonadal stages showing re-absortion and accumulation of reserves in nutritive cells at different seasons, whereas individuals from San Jorge Gulf had mature gametes during most of the year. Interannual variation of seawater temperature affected the gamete production and spawning duration in both populations. Higher temperatures during gametogenesis enhanced gonadal growth and gametes were released early. The major population differences found in gonadal cell composition highlight the plasticity in reproductive traits of A. dufresnii, and may be responsible for the wide distribution of A. dufresnii in different environments.

Consistency of faunal and floral assemblages within temperate subtidal rocky reef habitats

2001 ◽  
Vol 52 (6) ◽  
pp. 853 ◽  
Author(s):  
T. D. O'Hara
Keyword(s):  
Environmental Heterogeneity ◽  
Rocky Reef ◽  
Multivariate Statistical Analyses ◽  
Multivariate Statistical ◽  
Faunal Assemblages ◽  
Rocky Reefs ◽  
Macrobenthic Assemblages ◽  
Eastern Australia ◽  
Subtidal Rocky Reefs ◽  
Taxonomic Groups

Habitats defined by various biological and environmental variables are increasingly assumed to be surrogates for biodiversity. This study tested this assumption for temperate subtidal rocky reefs off south-eastern Australia by investigating the consistency of floral and faunal macrobenthic assemblages within habitats defined by dominant vegetation, substratum lithology, depth, wave exposure and region. Taxonomic groups included seagrasses, rhodophytes, chlorophytes, phaeophytes, hydroids, bryozoans, molluscs, polychaetes, pycnogonids and echinoderms. The results from multivariate statistical analyses indicated that, although variation between replicate samples is high, habitats as defined by dominant vegetation and, to a lesser extent, region supported consistent floral and faunal assemblages. The patterns did not emphasize a broad-scale biogeographic gradient, but rather the environmental heterogeneity of the coastline at scales of 10–100 km.

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