Distinguishing resident from transient species along marine artificial reefs

Abstract

Even if artificial reef studies heavily refer to the distinction between resident and transient species, there is still no widely-shared available method to distinguish objectively these two groups. Such an absence makes any comparison between studies difficult. This study aims to test whether the four objective distinction methods successfully applied to a 21-year-long time-series on fish assemblage in an English estuary may be as successful when applied to marine artificial reefs. For such a purpose, we tested each distinction tool separately with reference to four different artificial reef fish assemblage datasets. Three of them were drawn from the literature. Results indicate that none of these tools, used either individually or collectively, provide an efficient solution to distinguish resident species for the four datasets considered. We suggest that one of the major reasons for this failure may lie in the relative sampling size. Nonetheless, as these four datasets are representative of the datasets generally reported in the literature, tools capable of distinguishing reliably and efficiently resident from transient species along artificial reefs have yet to be developed. However, such a development requires fish residence to be previously and accurately defined by artificial reef scientists and managers.

Core and occasional species: A new way forward

“…This was not significantly different from the 29 core and 18 transient species suggested by Boisnier et al (2010) ( 2 1 = 2.100, p = 0.147) (Figure 4f).…”

“…6. Boisnier et al (2010) also used a second dataset, from a study of fish from an artificial marine reef in Australia. The data from table 2 in Branden et al (1994).…”

“…A 12th order model best described the pattern in the abundance ranked data. The glm model was as follows: y = −1.550 + 2.142x − 2.508e −4 x 4 + 3.125e −5 x 5 − 1.662e −6 x 6 + 4.796e −8 x 7 − 8.237e −10 x 8 + 8.684e −12 x 9 − 5.523e −14 x 10 + 1.948e −16 x 11 − 2.9 31e −19 x 12 There were four core groups (C1 = 9, C2 = 3, C3 = 11 and C4 = 16) totaling 39 species and including 95.0% of all individuals, and three oc- Artificial reef fish, Australia (Boisnier et al, 2010) y = −10.690 + 20.220x − 11.650x 2 + 3.492x 3 − 5.659e −1 x 4 + 5.4 05e −2 x 5 − 3.225e −3 x 6 + 1.237e −4 x 7 − 3.051e −6 x 8 + 4.678e −8 x 9 − 4.06 0e −10 x 10 + 1.524e −12 x 11 Lake fish, Wisconsin, USA (Hansen & Carey, 2015) y = 9.970 − 13.930x + 7.086x 2 − 1.356x 3 + 1.298e −1 x 4 − 6.905e −3…”

“…Some have used a single frequency point to divide communities into two groups (Barnes et al, 2016;Dolan et al, 2009;, while others have considered the presence of intermediate species (Boss & Silva, 2014;Supp et al, 2015). Alternative methods have included using species' variance to mean ratio, calculating Simpson's index for subgroups of species and fitting mathematical models to community data (Boisnier et al, 2010;van der Gast et al, 2011;Gray et al, 2005).…”

“…There has been criticism that many approaches have been arbitrary and a potential source of artifacts, although some studies have tried to use biological characteristics of the communities to help improve the reliability of species groupings (Barlow et al, 2010;Boisnier et al, 2010;Whittaker, 2015). As well as arbitrariness, any attempt to divide a community into core and occasional species presupposes the hypothesis that a binary division best describes a community.…”