Factors influencing patterns in distribution, abundance and diversity of sedimentary macrofauna in deep, muddy sediments of Placentia Bay, Newfoundland and the adjacent shelf

A nested sampling design and multivariate analyses were used to examine the community structure and spatial distribution of macrofauna on muddy substrates in Placentia Bay, Newfoundland and the adjacent shelf. The goal was to determine how macrofaunal communities are related to water column (e.g., surface productivity) and sediment characteristics (e.g., carbon and nitrogen content). Box core samples were collected at 10 sites (June & July of 1998) that were distributed from the head of the bay through the Eastern and Western Channels to the edge of the continental shelf. This is the first comprehensive study of Placentia Bay infauna and it is divided into three main components. Chapter 1 examines broad-scale patterns in community composition, diversity and abundance along an inshore/offshore gradient. Results indicate that the bay contains distinct inshore and offshore regions and benthic patterns are largely influenced by surface oceanography. Chapter 2 focuses on finer-scale patterns of distribution and abundance within the inshore region of the bay and reveals spatial patterns that were not evident in the analyses of broad-scale patterns in the previous chapter. Sediment-related factors and depth were important in explaining variation in inshore benthic patterns. Thus, contrasting the results of these two chapters suggests that different variables structure these communities at different scales. Because little biological sampling for benthos has been undertaken in this area, Chapter 3 provides a guide to the polychaetes, which are the dominant group of infauna in the study. Digital photographs of the key characteristics used to identify each species are provided to help bridge identification guides developed for other areas.