Subtidal invertebrate fouling communities of the British Columbian coast
| Autor: | Gartner, Heidi |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: | |
| Druh dokumentu: | Diplomová práce |
| Popis: | The British Columbian (BC) coast spans a 1000 km range of complex coastal geographic and oceanographic conditions that include thousands of islands, glacial carved fjords, exposed rocky coastline, and warm inlands seas. Very little is known about invertebrate fouling communities along the BC coast as studies are usually localised, focused in ports, or are conducted in the intertidal environment. This study provides the first high resolution study of invertebrate fouling communities of the BC coast by describing the identity, richness, diversity, and community composition of invertebrate fouling communities. Studying fouling communities on artificial surfaces was useful because the limiting resource (space) was defined, the researcher could control the timeframe, the samples were easily transported long distances, and the system can be easily replicated. Settlement structures were deployed in the spring of 2007 from the floating structures of marinas, docks, and aquaculture facilities. The deployment sites spanned a range of coastal environments from the Alaskan border to the southern tip of Vancouver Island, and included the Queen Charlotte Islands and Vancouver Island. The settlement arrays were collected roughly five months following deployment. Samples were transported back to the laboratory where all organisms present on the settlement arrays were identified to the lowest taxonomic level possible and their relative abundance recorded. The invertebrate fouling community was very species rich with 171 species identified and an additional 34 categories of unresolved taxa. This high richness may be attributed to the fact that the settlement arrays sampled the community as a whole, including motile and rare species. The richness per sample ranged from 1 to 29 species with the average being 12 species, of which more than one (1.25) was introduced to the BC coast. This invertebrate fouling community was dominated by relatively few species. Only 20% of the sessile species had an average cover over 1% and only 13% of the motile species had an average count over 0.5 individuals per sample. Of the sessile species, the Mytilus sp. complex was the most common with an average coverage of 35%. The Mytilus sp. complex was also found in 78% (126/162) of all samples. There were eleven introduced and twelve cryptogenic species identified in this study. Introduced species represented 30% of the dominant (=most abundant) sessile species and 20% of the dominant motile species study. The introduced and cryptogenic species were more abundant than native species when comparing abundance based on their distributions in the samples. The prominence and abundance of the introduced species in these communities may be an artefact of studying anthropogenic sites. However, it underscores the fact that the establishment and spread of non-native species are continuing along our coast, and that the strong competitive ability of a number of these species may have negative ecological and economic impacts. There were strong similarities in community composition across all geographic areas of the BC (Strait of Georgia-SOG, Juan de Fuca Strait- JFS, west coast of Vancouver Island-WCVI, Johnstone Strait-JS, and the north coast of the mainland-NC). The most common species assemblage was the Mytilus sp. complex and its associated species. The species assemblages observed across numerous geographic areas included species that were strong space competitors, had ranges that included the length of our study area, had key reproductive periods during the sampling period, and were able to recruit to artificial substrates. Anthropogenic structures may also be partially responsible for the strong similarities in community composition along the coast as we may be sampling species that are best adapted to these environments. Additionally, anthropogenic structures and activities may serve as vectors of species dispersal. Pairwise comparisons showed that the WCVI differed from the JFS and QCI in community composition in that the WCVI was strongly influenced by the Mytilus sp. community but the JFS and QCI were influenced by introduced and cryptogenic species. This study is the first to examine fouling communities that span the length of the BC coast. The data collected can be used as a baseline of comparison for future studies on subjects such as climate change, human mediated species introductions, and anthropogenic disasters. Graduate |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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