Temporal and spatial variation in macrofauna community composition imposed by ghost shrimp Callianassa filholi bioturbation

Abstract

The impact of bioturbation by the burrowing ghost shrimp Callianassa filholi on benthic community composition was examined in relation to seasonal and small-scale spatial changes. Sites of naturally occurring low and high densities of C. filholi on an intertidal sandflat represented hfferences in bioturbation activity throughout the year. Univariate and multivariate analyses showed significant differences in community composition between high-and low-density sites. The total number of species and total number of individuals were lower at high-density sites. A corophiid amphipod, Paracorophium escavatum and a small bivalve, Perrierina turneri, appeared to have the greatest discriminating significance wlth lower abundances of both species at sites of high C. filholi density. Even though differences between sites of different dens~ty pers~sted throughout the year, the impact of bioturbation depended on season. Bioturbation had the highest maximum correlation to changes in macrofauna1 community composition in winter, spring and, in association with seagrass blomass (Zostera novazelandica), in autumn. During summer, however, seagrass biomass contnbuted the most to observed differences and appeared to compensate for generally high bioturbation activity. The results imply that bioturbation impacted on macrofauna community composition over a small spatial scale and, although its impact varied seasonally, imposed patterns persisted throughout the year. As such, C. filholi can be considered a keystone species.

Effects of Callianassa kraussi on microbial biofilms and recruitment of macrofauna: a novel hypothesis for adult–juvenile interactions

“…The advantage of 'natural experiments' over manipulative caging experiments is that results are not influenced by experimental artifacts such as caging, which may confound the interpretation of results (Berkenbusch et al 2000). However, results from natural experiments can easily be misinterpreted due to high levels of natural variability, or by failing to take into account the affects of factors outside those being investigated.…”

“…that they have been cited as 'ecosystem engineers', but interactions among adult stages have dominated such research (Branch & Pringle 1987, Berkenbusch et al 2000, Berkenbusch & Rowden 2003, Siebert & Branch 2005, 2006.…”

Intertidal facilitation and indirect effects: causes and consequences of crawling in the New Zealand cockle

“…1A) has been shown to depress the density and abundance of smaller infaunal organisms (Berkenbusch et al 2000). However, C. filholi also coexists with larger macrofaunal organisms such as the New Zealand cockle Austrovenus stutchburyi (Veneridae) that may also be negatively affected by the presence of ghost shrimps.…”

“…In the intertidal zone, where physical stresses or biogenic disturbances are common and the community impact of predation and competition is relaxed, facilitation may be an important albeit hitherto largely overlooked structur-ing force (Bertness 1999). Soft-sediment environments, for instance, can be greatly affected by bioturbation or related biogenic disturbances that significantly depress the density and number of other benthic organisms (Rhoads & Young 1970, Brenchley 1981, Wilson 1981, Reise 1983, Suchanek 1983, DeWitt & Levinton 1985, Posey 1986, Flach 1993, Berkenbusch et al 2000, Bolam et al 2000. In such habitats, facilitation processes typically involve the immigration of a disturbance-resistant organism that stabilises the substrate and thereby paves the way for a range of otherwise excluded disturbance-sensitive species (Bertness 1999 and references therein).…”

Intraspecific burrow plasticity of an intertidal population ofCallianassa filholi(Crustacea: Decapoda: Thalassinidea) in relation to environmental conditions

“…The present study aims to address this shortfall by assessing burrow plasticity of the ghost shrimp Callianassa filholi Milne-Edwards, 1878 in relation to time and associated environmental factors. C. filholi is endemic to New Zealand and is one of the few Southern Hemisphere temperate species of callianassid shrimp to have received any biological investigation (Berkenbusch & Rowden 1998Berkenbusch et al 2000). To date, information on the burrow morphology has been limited to general observations (Devine 1966).…”