Trawl Communities and Organism Health
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chapter 6 TRAWL COMMUNITIES AND ORGANISM HEALTH Chapter 6 TRAWL COMMUNITIES AND ORGANISM HEALTH INTRODUCTION (Paralichthys californicus), white croaker (Genyonemus lineatus), California The Orange County Sanitation District scorpionfish (Scorpaena guttata), ridgeback (District) Ocean Monitoring Program (OMP) rockshrimp (Sicyonia ingentis), sea samples the demersal (bottom-dwelling) cucumbers (Parastichopus spp.), and crabs fish and epibenthic macroinvertebrate (= (Cancridae species). large invertebrates that live on the bottom) organisms to assess effects of the Past monitoring findings have shown that wastewater discharge on these epibenthic the wastewater outfall has two primary communities and the health of the individual impacts to the biota of the receiving waters: fish within the monitoring area (Figure 6-1). reef and discharge effects (OCSD 2001, The District’s National Pollutant Discharge 2004). Reef effects are changes related to Elimination System (NPDES) permit the habitat modification by the physical requires evaluation of these organisms to presence of the outfall structure and demonstrate that the biological community associated rock ballast. This structure within the influence of the discharge is not provides a three dimensional hard substrate degraded and that the outfall is not an habitat that harbors a different suite of epicenter of diseased fish (see box). The species than that found on the surrounding monitoring area includes populations of soft bottom. As a result, the area near the commercially and recreationally important outfall pipe can have greater species species, such as California halibut diversity. Compliance criteria pertaining to trawl communities and organism health contained in the District’s NPDES Ocean Discharge Permit (Order No. R8-2004-0062, Permit No. CAO110604). Criteria Description C.5.a Marine Communities Marine communities, including vertebrates, invertebrates, and algae shall not be degraded. C.5.b Marine Resources The natural taste, odor, and color of fish, shellfish, or other marine resources used for human consumption shall not be altered. C.5.c Human Health Concerns The concentration of organic materials in fish, shellfish, or other marine resources used for human consumption shall not bioaccumulate to levels that are harmful to human health. 6.1 Discharge effects are changes in water and the monitoring area generally healthy? sediment quality caused by the release of treated effluent. Organic effluent particles sink to the ocean bottom where they METHODS become available as a food resource for many invertebrate species. If these Field Methods particles contain elevated contaminate loads, then the contaminants can Demersal fish and epibenthic bioaccumulate in these invertebrates. macroinvertebrates (EMI) species were Many demersal fish (e.g., bottom dwelling) collected in August 2010 and January 2011 feed directly or indirectly on these using a 7.6 meter wide, Marinovich, semi- invertebrates. Additionally, demersal fish balloon otter trawl net fitted with a 0.64 cm live in close association with these cod-end mesh net. The net was towed on sediments and consequently, have an the ocean bottom for 450 m at approximately increased probability of direct exposure to 2 knots along a pre-determined course. sediments containing discharged particles. Sampling was conducted at nine permit This transfer of chemical contaminants stations: inner shelf (36 m) Stations T2 and through consumption and adsorption make T6; middle shelf (60 m) Stations T1, T3, T11, demersal fish species particularly T12, and T13; and outer shelf (137 m) susceptible to physical abnormalities and Stations T10 and T14 (Figure 6-1). Two diseases (Johnson et al. 1992, 1993; Moore replicate hauls were conducted at the inner et al. 1997; Myers et al. 1993; Stehr et al. and outer shelf stations and three replicate 1997, 1998). hauls were conducted at the middle shelf stations during both surveys. These contaminants, especially lipid- soluble (lipophilic) compounds, such as Trawl caught specimens were identified to chlorinated pesticides (e.g., DDT) and the lowest possible taxon, typically to polychlorinated biphenyls (PCBs) that species. A minimum of 30 individuals of accumulate in organisms may be each fish species were measured transferred up the food chain to other fish, individually to the nearest millimeter and mammals, and birds at concentrations weighed to the nearest gram. Fish in excess several orders of magnitude higher than in of 30 individuals were enumerated in 1-cm surrounding sediments or water through the size classes and batch weighed. All fish process of biomagnification. Whether specimens were examined for external bioaccumulated or biomagnified, high tissue tumors, other lesions, and parasites since contaminant concentrations may result in gross external manifestations may indicate greater susceptibility to disease or contaminated sediments (Murchelano 1982). reproductive impairment (Arkoosh et al. The first 100 EMI were also enumerated by 1998). species and weighed to the nearest gram. Specimens with abundance greater than To assess these issues, the District uses 100 individuals were weighed in batches and tissue contaminant data to evaluate the abundance calculated based on the following aspects of permit compliance: 1) weight/abundance ratio. Fish and EMI are there temporal and/or spatial patterns in specimens that could not be identified in the the animal communities relative to the field were retained for further identification ocean outfall; 2); are contaminant and weighed and measured in the concentrations in fish muscle tissue laboratory. sufficient to pose a potential human health concern and 3) are the marine organisms in Fish from four target species were kept for 6.3 tissue chemistry (bioaccumulation) was used to examine the spatial patterns of analysis. These were: hornyhead turbot the fish assemblages in the District’s (Pleuronichthys verticalis), English sole monitoring area (Clarke 1993, Warwick (Parophrys vetulus), bigmouth sole 1993). Analyses included hierarchical (Hippoglossina stomata) and Pacific clustering with group-average linking based sanddab (Citharichthys sordidus). Pacific on Bray-Curtis similarity indices, and sanddabs were collected and analyzed as ordination clustering of the data using non- composite samples. The sampling metric multidimensional scaling (MDS). objective was to collect 10 individuals of at Data were averaged by station and least three of the four target species at both truncated to include only the middle shelf (60 outfall (T1/T12) and farfield (T11/T13) sites. m) stations since depth is a strong Muscle and liver contaminant environmental factor in delineating species concentrations from hornyhead turbot, clusters (OCSD 2004, 2011). Clarke and English sole, and the whole-body tissue of Warwick (2001) warn that clustering is less Pacific sanddabs were measured at both useful and may be misleading where there is outfall and farfield stations. Three size a strong environmental forcing, such as classes (length ranges) of Pacific sanddabs depth. Also, data outliers, such as species were tested: 0 (5–8 cm), 1 (9–13 cm), and 2 with random and/or patchy distributions that (14–16 cm). The analytes include mercury, can artificially skew community assessments total DDT (tDDT; the sum of six7 DDT (i.e., halfbanded rockfish) were removed isomers), total PCB (tPCB; the sum of 45 from the dataset for classification and PCB congeners), and 12 other chlorinated ordination analyses. Prior to the calculation pesticides. Organic analyte data was lipid of the Bray-Curtis indices, the data were normalized to reduce within sample square-root transformed in order to down- variability; organics concentrate in lipid weight the highly abundant species and tissue and lipid tissue concentration varies incorporate the importance of the less considerably between fish. A complete list common species (Clarke and Warwick of analytes tested is presented in Appendix 2001). The SIMPER (“similarity A. percentages”) routine was also used to determine inter- and intra-group species Data Analyses differences. Fish and EMI populations were summarized Community measures from Station T1 and in terms of total abundance and species, Station T11 were evaluated for long-term percent abundance, frequency of temporal and spatial patterns, and compared occurrence, and mean abundance per haul. with regional reference values from the 1994 In addition, mean number of species, Southern California Bight Pilot Project number of individuals, biomass, and (SCBPP), Bight’98, Bight’03, and Bight’08 diversity indices including Shannon-Wiener regional monitoring programs (Allen et al. (H’), Margalef’s Species Richness (d), and 1998, 2002, 2007). Swartz’s 75% Dominance (Dominance) were calculated for both fish and EMI. Fish biointegrity was assessed using the Dominance (the minimum number of fish response index (FRI). The Fish species accounting for 75% of abundance) Response Index is a biointegrity index is inversely proportional to numerical developed by Allen et al. (2001). The index dominance, such that low index values was developed using the abundances of all indicate high dominance (i.e., communities species relative to the pollution gradient are dominated by a few species). away from the Palos Verdes shelf during PRIMER v6 multivariate statistical software the 1970s. Allen et al. (2001) noted that the 6.4 FRI was an effective surrogate of fish other species comprised 5% or less of the community assemblages,