Hydrocarbon effects on fouling assemblages: the importance of taxonomic differences, seasonal, and tidal variation

Effects of hydrocarbon-contaminated substrata on recruitment of three species of fouling organisms were studied along the Louisiana gulf coast. Clay tiles (232 cm2) were exposed to crude oil, 10% water soluble fraction of crude oil, or 25 g/kg artificial seawater, and placed out at two locations, in two seasons, and at two tidal levels in an estuary near Port Fourchon, Louisiana. Bryozoan (Membranipora savartii) recruitment was significantly reduced in all experiments on crude oil-exposed tiles. However, oysters (Crassostrea virginica) and barnacles (Balanus eburneus) exhibited recruitment facilitation, and oysters grew to larger size, on crude oil-exposed tiles in 1-4 of the five experiments. When oyster larvae were exposed to the same treatments in the laboratory, settlement was, however, significantly depressed on crude oil-exposed tiles as compared with controls, although oyster size was larger on crude-oil exposed tiles. Recruitment on tiles exposed to the water soluble fraction of crude oil was similar to control tiles in nearly all experiments for all taxa. We suggest naturally occurring biofilms (which hydrocarbons facilitate) may promote or inhibit recruitment, depending on the taxon, because hydrocarbons facilitated recruitment only in field experiments, not in lab experiments without biofilms. However, stronger currents in the field experiments may have more rapidly diluted hydrocarbons, and hydrocarbon effects were not large in comparison with natural seasonal and tidal variation in recruitment.     

Visualization of spatial patterns and temporal trends for aerial surveillance of illegal oil discharges in western Canadian marine waters

This paper examines the use of exploratory spatial analysis for identifying hotspots of shipping-based oil pollution in the Pacific Region of Canada’s Exclusive Economic Zone. It makes use of data collected from fiscal years 1997/1998 to 2005/2006 by the National Aerial Surveillance Program, the primary tool for monitoring and enforcing the provisions imposed by MARPOL 73/78. First, we present oil spill data as points in a “dot map” relative to coastlines, harbors and the aerial surveillance distribution. Then, we explore the intensity of oil spill events using the Quadrat Count method, and the Kernel Density Estimation methods with both fixed and adaptive bandwidths. We found that oil spill hotspots where more clearly defined using Kernel Density Estimation with an adaptive bandwidth, probably because of the “clustered” distribution of oil spill occurrences. Finally, we discuss the importance of standardizing oil spill data by controlling for surveillance effort to provide a better understanding of the distribution of illegal oil spills, and how these results can ultimately benefit a monitoring program.     

Northern fulmars as biological monitors of trends of plastic pollution in the eastern North Pacific

Marine plastic debris is a global issue, which highlights the need for internationally standardized methods of monitoring plastic pollution. The stomach contents of beached northern fulmar (Fulmarus glacialis) have proven a cost-effective biomonitor in Europe. However, recent information on northern fulmar plastic ingestion is lacking in the North Pacific. We quantified the stomach contents of 67 fulmars from beaches in the eastern North Pacific in 2009-2010 and found that 92.5% of fulmars had ingested an average of 36.8 pieces, or 0.385g of plastic. Plastic ingestion in these fulmars is among the highest recorded globally. Compared to earlier studies in the North Pacific, our findings indicate an increase in plastic ingestion over the past 40years. This study substantiates the use of northern fulmar as biomonitors of plastic pollution in the North Pacific and suggests that the high levels of plastic pollution in this region warrant further monitoring.     

Entanglement of Australian sea lions and New Zealand fur seals in lost fishing gear and other marine debris before and after Government and industry attempts to reduce the problem

In recent years, Australian governments and fishing industry associations have developed guiding principles aimed at reducing the impact of fishing on non-target species and the benthos and increasing community awareness of their efforts. To determine whether they reduced seal entanglement in lost fishing gear and other marine debris, we analysed Australian sea lion and New Zealand fur seal entanglement data collected from Kangaroo Island, South Australia. Contrary to our expectations, we found that entanglement rates did not decrease in recent years. The Australian sea lion entanglement rate (1.3% in 2002) and the New Zealand fur seal entanglement rate (0.9% in 2002) are the third and fourth highest reported for any seal species. Australian sea lions were most frequently entangled in monofilament gillnet that most likely originated from the shark fishery, which operates in the region where sea lions forage--south and east of Kangaroo Island. In contrast, New Zealand fur seals were most commonly entangled in loops of packing tape and trawl net fragments suspected to be from regional rock lobster and trawl fisheries. Based on recent entanglement studies, we estimate that 1478 seals die from entanglement each year in Australia. We discuss remedies such as education programs and government incentives that may reduce entanglements.     

Water quality and fisheries in the Mersey estuary, England: A historical perspective

The Mersey estuary, NW England, once had a prolific fishery but in the aftermath of the industrial revolution water quality and fisheries declined and the Mersey became infamous as one of the most polluted rivers in Europe. Until relatively recently, almost all industrial and domestic effluents were discharged without treatment resulting in abominable fouling of the shoreline, and long anoxic reaches in the upper estuary during the summer. In addition, there were unknown biological impacts resulting from a complex mixture of dangerous substances present in the river. Over 1000 million pound has been spent to remedy this situation and there is unequivocal evidence that this has had the desired effect. Dissolved oxygen is now generally >60% saturation, salmon are now found at the tidal-limit and the estuary is becoming ever more popular for sea angling. The river is no longer an embarrassing liability but is now perceived as an important asset in the economic regeneration of this region of the United Kingdom.