Macrofaunal Spatial Patterns in Relationship to Environmental Variables in the Richibucto Estuary, New Brunswick, Canada

Abstract

Estuarine macrobenthos respond to a variety of environmental gradients such as sediment type and salinity, and organic enrichment. A relatively new influence, organic loading from suspended bivalve culture, has the potential to alter this response. A study on soft-bottom macrobenthic communities was carried out in the Richibucto estuary (46°4 0′N, 64°50′W), New Brunswick, Canada, with samples collected from 18 stations in late September and early October 2006. The site consisted of a large tidal channel originating upstream in a small river. The channel was punctuated by bag culture of oysters along its length. A total of 88 species were recorded. The mean values of abundance, species richness, and diversity (H′) of macrofauna were 11,199 ind. m −2 (ranged from 4,371 to 19,930 ind. m −2 ), 23.4 species grab −1 and 3.29 grab −1 , respectively. In general species richness and H′ increased from the upper estuary to the estuarine mouth. Multivariate analyses clearly exhibited the spatial distribution in community structure, which coincided with the locations along the estuary (the upper, the lower and the mouth), as well as inside and outside the channel. Species richness and diversity H′ showed strong positive correlations with salinity (21.2-25.2 ppt), and abundance was positively correlated with water depth (1.0-4.5 m). Abundance and species richness were negatively correlated with both of silt-clay fraction (3.3-24.8%) and sorting (σ I ). Species richness was also negatively correlated with organic content (1.9-12.7%). The BIO-ENV analyses identified silt-clay fraction, σ I and salinity as the major environmental variable combination influencing the macrofaunal patterns, and siltclay fraction as the single best-correlated variable.

Analysis of Benthic Invertebrate Communities as a Function of Distance from Two Fish-Processing Plant Effluent Discharges in New Brunswick, Canada

“…The abundance of invertebrates in this study was well within the range described by Shaw (1998) (mean abundance of 135-887 individual/m 2 ) for a comprehensive study of benthic invertebrates in PEI estuaries. The number of taxa found in our study was within the range found by Mallet et al (2006) and Lu et al (2008) at the furthest sampling stations (Tracadie and Lamèque 100 m). All other sites in this study had a lower number of taxa than those of the other studies by Lu et al (2008) and Mallet et al (2006), but those other sites had similar number of species found by Miron et al (2005) where 53% of the station sampled contained less than five species.…”

“…The number of taxa found in our study was within the range found by Mallet et al (2006) and Lu et al (2008) at the furthest sampling stations (Tracadie and Lamèque 100 m). All other sites in this study had a lower number of taxa than those of the other studies by Lu et al (2008) and Mallet et al (2006), but those other sites had similar number of species found by Miron et al (2005) where 53% of the station sampled contained less than five species. The TOC concentrations we measured (mean 25.3 ± 15 g/kg, n = 7) at both sites were similar to those measured by Parker (2008) (mean 22.4 ± 12.1 g/kg) at proximal sites.…”

“…ND not determined invertebrate abundance (1,261-19,930 individuals/m 2 ) than those of this study and a range of taxa from 2-35 depending on the sampling location. All of the sites sampled by Miron et al (2005), Mallet et al (2006), and Lu et al (2008) were similar to those sampled in our study, i.e., the main anthropogenic influence was from waters draining low-density agricultural and residential areas as well as forested areas (based on aerial photography and site visits). Those sites were also influenced by some oyster aquaculture (Miron et al 2005;Mallet et al 2006;Lu et al 2008).…”

“…All of the sites sampled by Miron et al (2005), Mallet et al (2006), and Lu et al (2008) were similar to those sampled in our study, i.e., the main anthropogenic influence was from waters draining low-density agricultural and residential areas as well as forested areas (based on aerial photography and site visits). Those sites were also influenced by some oyster aquaculture (Miron et al 2005;Mallet et al 2006;Lu et al 2008). The density of invertebrates at some of our sampling stations was greater than those of Mallet et al (2006) and less than those of Lu et al (2008).…”

“…Those sites were also influenced by some oyster aquaculture (Miron et al 2005;Mallet et al 2006;Lu et al 2008). The density of invertebrates at some of our sampling stations was greater than those of Mallet et al (2006) and less than those of Lu et al (2008). The abundance of invertebrates in this study was well within the range described by Shaw (1998) (mean abundance of 135-887 individual/m 2 ) for a comprehensive study of benthic invertebrates in PEI estuaries.…”