VERIFYING SUCCESS OF ARTIFICIAL REEFS IN THE HURON-ERIE CORRIDOR FOR LAKE STURGEON

Lake sturgeon (Acipenser fulvescens) were historically abundant in the Huron-Erie Corridor (HEC), a 160 km river/channel network composed of the St. Clair River, Lake St. Clair, and the Detroit River that connects Lake Huron to Lake Erie. In the HEC, most natural lake sturgeon spawning substrates have been eliminated or degraded as a result of channelization and dredging. To address significant habitat loss in HEC, multi-agency restoration efforts are underway to restore spawning substrate by constructing artificial spawning reefs. The main objective of this study was to conduct post-construction monitoring of lake sturgeon egg deposition and larval emergence near two of these artificial reef projects; Fighting Island Reef in the Detroit River, and Middle Channel Spawning Reef in the lower St. Clair River. We also investigated seasonal and nightly timing of larval emergence, growth, and vertical distribution in the water column at these sites, and an additional site in the St. Clair River where lake sturgeon are known to spawn on a bed of ~100 year old coal clinkers. From 2010-12, we collected viable eggs and larvae at all three sites indicating that these artificial reefs are creating conditions suitable for egg deposition, fertilization, incubation, and larval emergence. The construction methods and materials, and physical site conditions present in HEC artificial reef projects can be used to inform future spawning habitat restoration or enhancement efforts. The results from this study have also identified the likelihood of additional uncharacterized natural spawning sites in the St. Clair River. In addition to the field study, we conducted a laboratory experiment involving actual substrate materials that have been used in artificial reef construction in this system. Although coal clinkers are chemically inert, some trace elements can be reincorporated with the clinker material during the combustion process. Since lake sturgeon eggs and larvae are developing in close proximity to this material, it is important to measure the concentration of potentially toxic trace elements. This study focused on arsenic, which occurs naturally in coal and can be toxic to fishes. Total arsenic concentration was measured in samples taken from four substrate treatments submerged in distilled water; limestone cobble, rinsed limestone cobble, coal clinker, and rinsed coal clinker. Samples were taken at three time intervals: 24 hours, 11 days, and 21 days. ICP-MS analysis showed that concentrations of total arsenic were below the EPA drinking water standard (10 ppb) for all samples. However, at the 24 hour sampling interval, a two way repeated measures ANOVA with a Holm-Sidak post hoc analysis (α= 0.05) showed that the mean arsenic concentration was significantly higher in the coal clinker substrate treatment then in the rinsed coal clinker treatment (p=0.006), the limestone cobble treatment (p

Comparative Behavior of Wild and Hatchery Reared White Sea Bream (Diplodus sargus) Released on Artificial Reefs Off the Algarve (Southern Portugal)

Three hatchery produced and reared (HPR) and five wild white sea bream (Diplodus sargus) were double tagged with Vemco V8SC-2L acoustic transmitters and Floy Tag T-bar anchor tags, and released on artificial reefs located near a natural reef off the southern coast of Portugal. Passive telemetry was used to monitor movements of the white sea bream over a nine week period from April to June 2007. Differences in behavior at release, habitat association (artificial vs. natural reef), and in daily movements were registered. Wild fish moved from one habitat to the other with increased preference for the artificial habitat during the day, whereas HPR fish showed no site fidelity or consistent daily movement pattern and left the release site soon after release. Comparison of Minimum Convex Polygon (MCP) showed a higher area usage by wild fish. This experiment shows that these artificial reefs are used on a daily basis by wild white sea bream but apparently are not optimal release locations for hatchery produced white sea bream.

Residency, movements and habitat use of adult white seabream (Diplodus sargus) between natural and artificial reefs

Artificial reefs are used as management tools for coastal fisheries and ecosystems and the knowledge of habitat use and fish movements around them is necessary to understand their performance and improve their design and location. In this study wild specimens of Diplodus sargus were tagged with acoustic tags and their movements were tracked using passive acoustic telemetry. The monitored area enclosed a natural rocky reef, an adjacent artificial reef (AR) and shallower sandy bottoms. Most of the fish were close to full time residents in the monitored area. Results revealed that D. sargus use the natural reef areas on a more frequent basis than the AR. However, excursions to the adjacent AR and sandy bottoms were frequently detected, essentially during daytime. The use of acoustic telemetry allowed a better understanding of the use of artificial reef structures and its adjacent areas by wild D. sargus providing information that is helpful towards the improvement of AR design and location. (c) 2013 Elsevier Ltd. All rights reserved.

The comparative effects of habitat complexity on faunal assemblages of northern temperate artificial and natural reefs

Several north temperate marine species were recorded on subtidal hard-substratum reef sites selected to produce a gradient of structural complexity. The study employed an established scuba-based census method, the belt transect. The three types of reef examined, with a measured gradient of increasing structural complexity, were natural rocky reef, artificial reef constructed of solid concrete blocks, and artificial reef made of concrete blocks with voids. Surveys were undertaken monthly over a calendar year using randomly placed fixed rope transects. For a number of conspicuous species of fish and invertebrates, significant differences were found between the levels of habitat complexity and abundance. Overall abundance for many of the species examined was 2-3 times higher on the complex artificial habitats than on simple artificial or natural reef habitats. The enhanced habitat availability produced by the increased structural complexity delivered through specifically designed artificial reefs may have the potential to augment faunal abundance while promoting species diversity. 

Artificial Habitats for Fisheries Enhancement in the Australian Region

This paper outlines developments over about 20 years in the construction of and ecological research on artificial reefs, fish aggregation devices (FAD's), and other artificial habitats designed to enhance fish populations and fisheries in the Australian region (including New Zealand and Papua New Guinea). Work was initially carried out on multicomponent reefs using a variety of waste materials, as well as some specially constructed concrete and steel structures. Later studies concentrated on single-component reefs, again mainly using waste materials. Although no definitive conclusions were reached on the relative effectiveness of the different materials used, waste motor vehicle tires and derelict ships were generally judged to be the best all-around materials for single-component reef construction in sheltered estuarine and offshore marine environments, respectively, in this region. FAD's comprising polyvinylchloride pipe sparbuoys (or in some areas polyurethane foam floats) attached to railroad car wheel anchors by polyethylene rope and chain, and supporting attractor drapes of synthetic mesh webbing, also provedtobegenerallysuccessfulin thisarea. Overall conclusions for the Australian region include the predominant use of waste materials in artificial reef construction, which has been primarily aimed at recreational fisheries enhancement; the successful use of FAD's for both recreational and commercial fisheries enhancement; the need for further and better planned research into and monitoring of the effectiveness of both of these enhancement methods; and the need for future research into the effectiveness of unfished "artificial habitat reserves" in enhancing fisheries production from surrounding fished areas.

Assessment of Natural and Manmade Materials in US Artificial Reef Programs

Natural coral reefs are in a state of serious decline worldwide. The pressures of over fishing, recreational activities, environmental pollutants, and global warming have stressed these marine ecosystems to the breaking point. One of the oldest methods of augmenting natural reef systems is the implementation of artificial reefs. These projects are not as simple as dumping waste or scrap materials in offshore areas. Proper material selection is vital to produce a healthy artificial marine habitat that is completed on schedule and on budget. This Capstone Project will evaluate the most commonly used materials and provide a comparison of their strengths and weaknesses. This comparison provides a valuable tool for project managers as they begin the reef planning process.