Predicting Success of Range-Expanding Coral Reef Fish in Temperate Habitats Using Temperature-Abundance Relationships

Abstract

An 18-year database of coral reef fish expatriation poleward in South East Australia was used to estimate persistence of coal reef fish recruits on temperate reefs. Surveys have identified over 150 coral reef fish species recruiting to temperate reefs at latitudes of 34 • S (Sydney) and 60 species to 37 • S (Merimbula) with 20 and 5 species respectively overwintering in at least 1 year over the study duration. We developed indices of vulnerability of key species to drops in water temperatures, by relating drops in abundances of species to temperature drops. Twenty species were ranked according to their temperature vulnerability. Overall, the families Chaetodontidae (butterflyfishes), Acanthuridae (surgeonfishes), Labridae (wrasses) and Pomacetnridae (damselfishes) had similar cold-water tolerance. However, there was considerable variability within families, for instance in the Pomacentridae, species from the genus Abudefduf appeared to have better cold-temperature tolerance than the other species. Predicted minimum overwintering temperature varied from 15.6 • C to 19.8 • C, with some species showing lower Tzero at Merimbula, the more poleward location. There was general concordance between a species' tolerance to cold-water and its tendency to occur as an overwinter but also notable exceptions. So while this work demonstrates the potential utility of tolerance to seasonal temperature drops as a means to predict range expansion capacity of vagrant species, the exceptional cases serve to highlight alternative factors. Specifically, tolerance to seasonal cooling of water is not the only important factor when predicting the range expansion capacity of a species. Factors affecting the general abundance of the vagrants, such as habitat suitability and competitor/predator environments will also be critical where overwinter survival becomes a lottery.

Trophic niche segregation allows range‐extending coral reef fishes to co‐exist with temperate species under climate change

“…The remainder of the tropical species were not observed as far south as Sydney. Furthermore, the peak temperatures (below which abundances start to decline) of all the selected tropical species (Booth, Beretta, Brown, & Figueira, 2018) are lower than the mean winter temperatures at these two study sites (Table S2). All species studied are omnivorous (Lieske & Myers, 1994;Myers, 1991;Randall, 1985).…”

The shape of abundance distributions across temperature gradients in reef fishes

“…The relationship between temperature and maximum abundance suggests at least partial predictability of species‐level maximum abundance response to future temperature changes (Booth et al . ), and the opportunity to predict changes in maximum abundance across species ranges (Lenoir & Svenning ; Martinez‐Gutierrez et al . ).…”

“…The relationship between temperature and maximum abundance suggests at least partial predictability of species-level maximum abundance response to future temperature changes (Booth et al 2018), and the opportunity to predict changes in maximum abundance across species ranges (Lenoir & Svenning 2013;Martinez-Gutierrez et al 2018). Such approaches add to estimates of biodiversity change in response to warming that are generally based on changes in occupancy probabilities changes in abundance are an important component of temperature-driven biodiversity change, as well as changes in ecosystem function and services (Waldock et al 2018).…”

Conservation value of a subtropical reef in south-eastern Queensland, Australia, highlighted by citizen-science efforts

“…Although subtropical reefs may have lower coral diversity than do tropical reefs and do not rapidly form an accreting reef structure (McIlroy et al 2019), the live coral cover forming subtropical reefs can be comparable to that of tropical reefs in some locations (Harrison et al 1998;Wallace and Rosen 2006;Dalton and Roff 2013). Subtropical reefs offer important ecological habitat for migratory marine life such as humpback whales and recruiting coral reef fish (Booth et al 2018;Noad et al 2019). They also have social, cultural and economic value through activities such as fishing and tourism (Ross et al 2019;Ruhanen et al 2019).…”