Geographic differences in recruitment and population structure of a temperate reef fish

Abstract

The purpose of this study. was to assess the importance of pre-and post-settlement processes in the temperate reef fish Tautogolabrus adspersus at multiple spatial scales and in 2 distinct regions, Newfoundland, Canada, and the Gulf of Maine, USA. We examined a total of 20 sites (separated by 100 to 1000 m) nested within 10 locations (separated by ca 10 km). Greater numbers of adult fish were observed in Newfoundland than in the Gulf of Maine; however, higher abundances of newly recruited fish occurred in the Gulf of Maine. An experiment in which we provided standardized habitats in both regions also revealed that recruitment was higher in the Gulf of Maine than Newfoundland. In the Gulf of Maine, variation in the densities of adults and newly recruited fish was most pronounced among sites, but in Newfoundland we detected pronounced variability at both the site and location scales. Algal height was not associated with among-site variability in the abundances of recruits or adults. Algal coverage, however, was an important predictor of variability of fish abundance in the Gulf of Maine but not in Newfoundland. The age structure of Newfoundland populations suggests that strong recruitment years are rare, while in the Gulf of Maine the age structure is consistent with the expectation of declining abundance with age. Our data suggest that pre-settlement processes are not of primary importance to cunner populations in the Gulf of Maine. Rather, we hypothesize that habitatrelated differences in post-settlement processes are the most significant factors affecting these populat i o n~. However, in Newfoundland the evidence gathered thus far supports the hypothesis that episodic settlement is responsible for much of the variation in population size in this region.

Fish-seaweed association on temperate reefs: do small-scale experiments predict large-scale patterns?

“…Similarly, Caselle & Warner (1996) demonstrated a correlation between microhabitat attributes and recruitment of Thalassoma bifasciatum that was not evident among sites around St Croix, US Virgin Islands. On temperate reefs, Levin (1991Levin ( , 1993 showed that the wrasse Tautogolabrus adspersus selected microhabitats with high coverage of filamentous algae at settlement, but among-reef variability in filamentous algae did not predict large-scale patterns of recruitment (Levin et al 1997). The inability to scale-up may occur because of low variability of the preferred substratum (Tolimieri 1995) or because the habitat signal may be scale-dependent (Syms 1995, Syms & Jones 1999.…”

“…Moreover, large-scale patterns of fish abundance often correlate with habitat characteristics of reefs (e.g. Levin et al 1997). While the literature is replete with studies of fish-habitat associations, most of these studies are conducted at a single spatial scale.…”

Evidence for density-dependent mortality in recruitment of a temperate reef fish, cunner Tautogolabrus adspersus, among similar reefs in the vicinity of an anthropogenic disturbance

“…We coded habitat characteristics into 2 functional groups, structure (filamentous and fleshy algae types) and non-structure (sand, gravel, and crustose algae), because these characteristics of the habitat are known to be important for recruitment in cunner (Levin 1991, Levin et al 1997). We define 'gravel' as rocks less then 5 cm in diameter with no algal cover.…”

“…It is also important to note that after settlement an overall decrease in recruit abundance at a reef was assumed to be mortality since cunner recruits possess very limited movement (Tupper & Boutilier 1995a, 1997. Numerous studies have found that differences in macroalgae type and structure are essential determinants of recruitment in temperate reef fish species (Jones 1984, Carr 1989, Connell & Jones 1991, Levin 1991, 1994b, Levin et al 1997. For example, structural quality of habitat is known to be an important determinant of post-settlement recruit abundance in cunner (Levin 1993, 1994b, Tupper & Boutilier 1995a.…”

Fish assemblages along a morphodynamic continuum on three tropical beaches

“…One of the primary bases for understanding fish assemblages is the knowledge of their distribution and abundance and their relationship with abiotic factors (Inoue et al, 2008), as well as factors that will limit or affect a change in population (Levin et al, 1997). Several studies from different regions have emphasized abiotic factors, such as temperature and salinity (Harrison & Whitfield, 2006), salinity and turbidity (Cyrus & Blaber, 1992;Barletta et al, 2005), turbidity (Cyrus & Blaber, 1987;Abou-Seedo et al, 1990), morphodynamic models (Inui et al, 2010), and input of freshwater and river flow (Barletta et al, 2005;Vinagre et al, 2009;Baptista et al, 2010;Castillo-Rivera, 2013) as factors that influence the abundance of young fish in these shallow water habitats.…”