Chapter 6. Demersal Fishes and Megabenthic Invertebrates

INTRODUCTION TheCityofSanDiegoOceanMonitoringProgramwas designedtomonitortheeffectsofthePointLomaOcean Demersal fishes and megabenthics are conspicuous Outfall (PLOO) on the local marine environment. members of continental shelf and slope habitats, This chapter presents analyses and interpretation and assessment of their communities has become of demersal fish and megabenthic invertebrate data an important focus of ocean monitoring programs collectedunderthis programduring 2005.Along-term throughout the world. Such assemblages have analysis of changes in these communities from 1991 been sampled for more than 30 years on the through 2005 is also presented. mainland shelf of the Southern California Bight (SCB), primarily by programs associated with municipal wastewater and power plant discharges MATERIALS AND METHODS (Cross and Allen 1993). More than 100 species of demersal fish inhabit the SCB, while the Field Sampling megabenthic invertebrate fauna consists of more than 200 species (Allen 1982, Allen et al. 1998). A total of 12 trawls were performed during 2 surveys For the region surrounding the Point Loma off Point Loma in 2005. The trawling area extends Ocean Outfall (PLOO), the most common trawl- from about 8 km north to 9 km south of the PLOO. caught fishes include Pacific sanddab, longfin Six stations (SD7, SD8, SD10, SD12, SD13, SD14) sanddab, Dover sole, hornyhead turbot, California are located along the 100-m contour and were tonguefish, plainfin midshipman, and yellowchin sampled during January andL a J o l lJuly a (Figure 6.1). A sculpin. Common trawl-caught invertebrates single trawl was performed at each station using a include relatively large taxa such as sea urchins 7.6-m Marinovich otter trawl fitted with a 1.3-cm and sea stars. cod-end mesh net. The net was towed for 10 minutes

San Diego River The structure of these communities is inherently S a n D i e g o SD14 ! variableandmaybeinfluencedbybothanthropogenic

L o m a B and natural factors. Anthropogenic factors, such as SD13 i eg o ay ! D an inputs from ocean outfalls and storm drain runoff, P o i n t S can impact demersal fishes and megabenthic C o r o n a d o

SD12 invertebrates because they live in close proximity ! ll to sediments potentially altered by these inputs. Point Loma Outfa 10 m

Natural factors include prey availability (Cross et al. SD10 ! 1985), bottom relief and sediment structure (Helvey SD8 and Smith 1985), and changes in water temperature ! associated with large scale oceanographic events LA5 such as El Niños (Karinen et al. 1985). These natural SD7 ! factors can impact the migration of adult fish or the 150 m LA4 4 km

100

0m80 20 150 m 60 0 1 2 3 4 5

recruitment of juveniles into an area (Murawski m m m 1993). Population fluctuations that affect diversity and abundance may also be due to the mobile nature Figure 6.1 of many species (e.g., schools of fish or aggregations Otter trawl station locations, Point Loma Ocean Outfall Monitoring Program. of urchins). 61 bottom time at a speed of about 2.5 knots along a of classification (cluster analysis) by hierarchical predeterminedheading. Detailed methods for locating agglomerative clustering with group-average the stations and conducting trawls are described in the linking. The fish abundance data were square- City ofSanDiego QualityAssurancePlan(Cityof San root transformed and the Bray-Curtis measure of Diego in prep). dissimilarity was used as the basis for classification. The SIMPER (“similarity percentages”) analysis Trawl catches were brought on board ship for sorting was used to identify individual species that and inspection. All organisms were identified to determined inter- and intra- group differences. species or to the lowest taxon possible. If an animal could not be identified in the field, it was returned to the laboratory for further identification. For fish, RESULTS the total number of individuals and total biomass (wet weight, kg) were recorded for each species. Fish Community Additionally, each individual fish was inspected for the presence of external parasites or physical Thirty-five species of fish were collected in the area anomalies (e.g., tumors, fin erosion, discoloration) surrounding the PLOO during 2005 (Table 6.1). The and measured to the nearest centimeter according to total catchforthe yearwas7596fishes representingan standard protocols (see City of San Diego in prep). average of 633 individuals/haul. Halfbanded rockfish When extremely large hauls of fish were obtained, a was the overall most abundant taxon collected in 10 kg subsample was size classed. Total abundance 2005, although most of the individuals occurred in was then estimated by multiplying the number of just 2 hauls. The 2 trawls collected at stations SD10 individuals per 1.0 kg by the total fish biomass, and and SD12 in January included 2537 hafbanded the number of fish per size class was estimated based rockfish, representing 1/3 of the total catch. Only 292 on the proportion of each size class in the measured other halfbanded rockfish were collected from the fish. For invertebrates, the total number of individuals remaining10trawls.Overallthisspeciesaccountedfor was recorded per species. When the white sea urchin, 37% of the total catch. Pacific sanddab, typically the Lytechinus pictus, was collected in large numbers, its most abundant fish in this area, was the second most abundance was estimated by multiplying the total abundant species (2532 individuals) and comprised number of individuals per 1.0 kg subsample by the 33% of the total catch. These 2 species, as well as total urchin biomass. Dover sole, yellowchin sculpin, plainfin midshipman, and shortspine combfish occurred in every haul. Data Analyses Other common fishes present in at least half of the hauls were longspine combfish, slender sole, English Populations of each fish and invertebrate species were sole, pink seaperch, stripetail rockfish, greenstriped summarizedin terms of percent abundance, frequency rockfish, California tonguefish, roughback sculpin, of occurrence and mean abundance per occurrence. In greenspotted rockfish, and hornyhead turbot. These addition, species richness (number of species), total 10 species tended to be relatively small with average abundance, and Shannon diversity index (H') were lengths <20 cm (Appendix C.1). calculated for both fish and invertebrate assemblages at each station. Total biomass was also calculated for Fish abundance and biomass were highly variable each fish species by station. during 2005. Mean abundance ranged from 288 to 1368 fish per haul (Table 6.2).The largest hauls were Multivariate analyses were performed on the collected at both of the nearfield stations, SD10 and 6 stations using PRIMER software to examine SD12, due to the large halfbanded rockfish catches spatio-temporal patterns in the overall similarity described above. Among the farfield station pairs, of fish assemblages in the region (see Clarke abundances at northern stations SD13 and SD14 was 1993, Warwick 1993). These analyses consisted nearly twice that of southern stations SD7 and SD8.

62 Table 6.1 Table 6.2 Demersal fish species collected in 12 trawls in the Summary of demersal fish community parameters PLOO region during 2005. Data for each species are for PLOO stations sampled during 2005. Data are expressed as: percent abundance (PA); frequency of presented for cumulative (total) and mean number of occurrence (FO); mean abundance per occurrence species, abundance, diversity (H'), and biomass (BM) (MAO). (kg, wet weight); n=2 for each station. Species PA FO MAO No. of Species Halfbanded rockfish 37 100 236 Station Total Mean Abund H' BM Pacific sanddab 33 100 211 Longspine combfish 8 92 52 SD7 19 15 288 1.40 4.4 Dover sole 7 100 47 SD8 22 17 315 1.48 5.7 Yellowchin sculpin 5 100 31 SD10 24 18 1368 1.03 24.6 Plainfin midshipman 2 100 10 SD12 22 17 762 1.56 11.3 Shortspine combfish 1 100 7 SD13 26 19 562 1.66 10.3 Slender sole 1 50 12 SD14 23 18 506 1.55 14.3 English sole 1 83 6 Pink seaperch 1 92 5 For example, the highest biomass of any haul Stripetail rockfish 1 50 9 Greenstriped rockfish 1 92 4 (38.1 kg) occurred at station SD10 in January and was Spotfin sculpin <1 25 9 due to large numbers (1929) of halfbanded rockfish California tonguefish <1 58 4 weighing approximately 33 kg. Squarespot rockfish <1 17 13 Roughback sculpin <1 58 3 In contrast to abundance and biomass, values for Blacktip poacher <1 33 5 species richness and diversity (H') varied little Greenspotted rockfish <1 50 4 and were relatively low in 2005 (Table 6.2). The Greenblotched rockfish <1 42 3 mean number of species ranged from 15 to 19 Hornyhead turbot <1 67 2 Bigfin eelpout <1 17 6 per haul, while the (cumulative) total number of Blackbelly eelpout <1 25 3 species was less than 30 at all stations over the year. Juvenile rockfish <1 17 2 Diversity values were less than 2 at all stations. Pygmy poacher <1 33 2 These relatively low diversity values are due to the California skate <1 33 2 predominance of Pacific sanddabs or, in the case of Spotted cuskeel <1 33 2 SD10 and SD12, halfbanded rockfish. Chilipepper rockfish <1 8 4 Bigmouth sole <1 25 1 Fluctuating populations of dominant species have Bluespotted poacher <1 17 1 Juvenile sanddab <1 8 2 been the primary factor contributing to variation Pacific argentine <1 17 1 in the structure of the fish community off Point Bay goby <1 8 1 Loma since 1992 (Figure 6.2, Figure 6.3). For Bluebanded ronquil <1 8 1 example, mean species richness has remained fairly Flag rockfish <1 8 1 consistent over the years, ranging from 10 to 20 Longfin sanddab <1 8 1 species per station, while mean abundances have Pink rockfish <1 8 1 fluctuated substantially (e.g., 93–1368 individuals) Shiner perch <1 8 1 (Figure 6.2). These fluctuations in abundance have As in past years, this difference was primarily due been greatest at stations SD10, SD12, SD13, SD14 to substantial numbers of Pacific sanddab present at and generally reflect differences in populations of SD13 and SD14 (Appendix C.2). The wide range in several dominant species, especially the Pacific total fish biomass per haul (mean=4.4–24.6 kg) was sanddab (Figure 6.3). Overall, none of the observed generally due to large hauls of halfbanded rockfish changes appear to be associated with wastewater and Pacific sanddabs, which resulted in relatively discharge from the Point Loma outfall. high biomass where they occurred in high numbers. 63 collected from1992through 2005;n=41992-2002,n=3in2003,andn=2during 2004-2005. species fish abundant most seven the for station PLOO per individuals) of (number abundance mean Annual Figure 6.3 of demersalfishcollectedfrom1992through2005;n=41992-2002,n=3in2003,andn=2during2004-2005. station PLOO per individuals) of (number abundance and species) of (number richness species mean Annual Figure 6.2 Abundance 1000 150 200 100 2 1 150 200 400 Species Richness 500 1 2 3 400 25 10 15 20 50 50 00 00 50 00 00 00 00 5 0 0 0 0 0 Longspine combfish L Halfbanded rockfish Halfbanded rockfish Pacific sanddab ongfin sanddab

92 92 93 93

94 94

95 95

96 96 97 97 98 98 99

99 South farfield 00 00 01

01 02 SD8 SD7 02 03 03 04 04 05

64 05 Nearfield 150 200 100 100 200 150 400 100 200 300 500 50

50 50

SD12 SD10 Abundance 1 1250 1500 South farfield 0 0 0 000 500 750 250 0 Doversole Plainfin midshipman Yellowchin sculpin 92 SD8 SD7 North farfield 93

92

94 93 SD13 SD14 95 94

Nearfield 96 95 97 96 SD12 SD10 98 97 99 98 00 99

North farfield 00 01 01 02

02

SD14 SD13 03 03 04 04 05 05 80

40 Distance of Dissimilarity

0 ABCDEFGH I J

Station Groups

Year 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 SD7 SD8 SD10 SD12 SD13 SD14 Figure 6.4 Results of ordination and classification analysis of demersal fish collected at PLOO stations SD7–SD14 between 1991 and 2005 (July surveys only). Data are also presented as a matrix showing distribution over time.

Classification analyses of fish data from July entities. Each of these groups was unique in surveys between 1991 and 2005 resulted in terms of size (i.e., lower species richness and 10 major cluster groups (station groups A–J) abundances) and/or composition (e.g., fewer (see Figure 6.4). All of the assemblages were of the more common flatfish such as Pacific dominated by Pacific sanddabs and were sanddabs). Groups A, B, and C were all fairly differentiated by relative abundances of this small, averaging 7–11 species and less than 75 and other common species, or by the presence individuals per haul. Pacific sanddabs dominated of rare species. None of these differences appear the assemblages represented by groups A–C, but to be associated with the PLOO discharge during average abundance was low relative to the other 2005 or in years past. Instead, differences in fish assemblages. Other important species in these assemblages seem to be related to oceanographic groups included halfbanded rockfish (group A), events (e.g., El Niño conditions in 1991/1992 bigmouth sole and yellowchin sculpin (group and 1998) or location. For example, stations B), and Dover sole (group C). Groups D, E, SD7, SD8, and SD12 frequently grouped apart and F were composed solely of station SD12 from the remaining stations. Characteristic in 1998, 1997, and 2003–2004, respectively. species for each station group are described These 3 station groups were similar in size to the below (Table 6.3). remaining 4 groups (G, H, I, J) but differed in composition. For example, group E was unique Station groups A–F comprised 6 unique due to the presence of squarespot rockfish and assemblages formed by 1 or 2 station/survey vermilion rockfish (Table 6.3).

65 Table 6.3 Summary of the most abundant species comprising station groups A–J defined in Figure 6.4. Data include number of hauls, overall similarity within each group, mean species richness, and mean abundance for each station group, as well as the mean abundance of species that together account for 90% of the similarity (or 90% of total abundance for groups with n < 2). Values in bold type indicate the species that are most representative of a station group (i.e., 3 highest similarity/SD values > 2 for groups with n > 2, or highest abundance for groups with n

Number of hauls 1 2 2 1 1 2 9 12 15 45 Overall similarity na 57 62 na na 70 65 60 61 63 Mean species richness 7 11 11 16 19 15 12 12 16 15 Mean abundance 44 68 74 261 231 274 217 100 209 376

Species Mean Abundance

Bigmouth sole 3 Blackbelly eelpout 6 California tonguefish 4 3 Dover sole 6 36 32 14 9 14 30 Juv sanddab 2 Greenblotched rockfish 2 8 Greenspotted rockfish 1 Greenstriped rockfish 1 Gulf sanddab 1 Halfbanded rockfish 16 60 27 3 7 Longfin sanddab 1 3 4 6 3 8 Longspine combfish 2 7 34 2 15 Pacific sanddab 23 46 48 75 110 105 118 61 143 247 Pink seaperch 1 2 5 Plainfin midshipman 2 116 41 5 2 9 Roughback sculpin 2 Shortspine combfish 12 2 6 Slender sole 27 6 Spotfin sculpin 1 6 Spotted cuskeel 2 Squarespot rockfish 23 Stripetail rockfish 22 15 Vermilion rockfish 6 Yellowchin sculpin 5 4 9 16

Station group G comprised most stations sampled Station groups H and I included some hauls from during the 1991/1992 El Niño, as well as station stations SD10 and SD12, but consisted primarily SD10 sampled in 1995. This assemblage averaged of fish assemblages from the southern farfield 12 species and 217 individuals per haul and was stations SD7 and SD8 during two different dominated by Pacific sanddabs, Dover sole, and temperature regimes. Group H contained one or plainfin midshipman. It differed from the other both of these stations from 1992, 1995–1998, assemblages in the relative contributions of gulf and 2002 while group I contained one or both of sanddab, greenblotched rockfish, greenstriped these stations from 1991–1996 and 2003–2005. rockfish, and shortspine combfish. Group H averaged 12 species and an abundance

66 with n 2 for groups with n > 2, or highest abundance for groups of total abundance for groups with n < 2). Values in bold type indicate the species that are most representative station group, as well as the mean abundance of species that each together account for for abundance 90% of mean the include and similarity (or richness, 90% species Data mean group, 6.4. each within Figure similarity overall hauls, in of number defined A–J groups station comprising species abundant most the of Summary Table 6.3 Longfin sanddab Longfin Halfbanded rockfish Gulf sanddab Greenstriped rockfish Greenspotted rockfish Greenblotched rockfish Juv sanddab Dover sole California tonguefish Blackbelly eelpout Bigmouth sole Species Mean abundance Mean speciesrichness Overall similarity Number ofhauls Longspine combfish Yellowchin sculpin Vermilion rockfish Stripetail rockfish Squarespot rockfish Spotted cuskeel Spotfin sculpin Slender sole Shortspine combfish Roughback sculpin midshipman Plainfin Pink seaperch Pacific sanddab

16 63 376 61 209 60 100 217 65 274 70 231 261 na 74 na 68 62 44 57 na 34 87 1 0 1 113247 143 61 118 105 110 75 48 46 23 1 45 15 1 15 16 12 1 12 9 12 2 15 19 1 16 1 11 2 11 7 2 1 1 1 Group A 3 3 5 2 Group B 63 491 30 14 9 14 32 1 2 36 6 2 2 Group C 116 Mean Abundance 7 Group D 60 23 8 6 Group E 27 34 27 12 6 2 Group F 22 41 2 4 Group G 3 4 6 9 4 9 2 2 5 Group H 7 3 8 3 15 2 6 6 5 2 Group I 16 15 6 Group J not been associated with degraded environments. not with environments. been degraded associated are have and infection tumors specific Dover a from these Project likely Research communication), Water (personal Coastal Southern the of California Allen J. M. Dr. to According tumors. have to found were population) Dover For 2005. 1% of the than (less soles 2 only Dover example, during Loma Point off populations comprising J group Station others. the from group this differentiated also abundances rockfish halfbanded and sole Dover of contribution relative The years. these during of numbers higher sanddabs, with reflecting the cooler water but temperatures by sole, Dover and represented sanddabs Pacific by dominated also was assemblage I group The significantly declined. water, colder prefer to tends that conditions when Niño populations of Pacifics, El a species 1998 with associated water warmer to group H (see Table 6.3). This is pattern likely due at abundance average lower the caused sanddabs Pacific of numbers low the A–C, groups with As substantially lower than at the other station groups. the hauls in this station group, their numbers were of proportion large a comprised sanddab Pacific Although sole. Dover and rockfish, combfish, halfbanded shortspine of contributions relative the in assemblages other the from differed They by dominated was Pacific sanddab, Dover sole, and longfin group sanddab. this by represented assemblage The haul. per individuals 100 just of p other of occurrences the and absent, was rot Fin from the others. group this in stations distinguish species yellowchin sculpin. and The relatively high sole, numbers of these Dover three sanddabs, Pacific by dominated was the and abundance had mean highest group This SD14. and SD13 stations, northernmost 2 the from collected samples most located around or north of the outfall, and included through 2005. This group comprised sites primarily hysical abnormalities were generally low in were generally fish abnormalities hysical

Physical Abnormalities andParasitism

45 station/survey entities from 1993 from entities station/survey 45

was the largest station group, group, station largest the was

67

the sea cucumbersea the and sea hare sea the remaining stations demonstrated large peaks large demonstrated stations remaining the were consistently catches low at stations SD13 and invertebrate SD14, while annual average The stations. among greatly differed have abundance in changes contrast, In stations. among similar been have change of patterns the although 1992, since species 20 to 5 from averaged has richness throughout theSCB. a As with the fishes, invertebrate abundances varied spider pen sea the included Acanthoptilum hauls the of 1/2 in least at occurred that species common Other catch. trawls and accounted allfor in present92% was ofIt species.captured thefrequently total invertebrate Lytechinus ( invertebrates, r megabenthic 24,069 of total A surveys. all during and was at collected present all sanddabs stations cincinnatus Dominance urchin. of this of dominance numerical the to due area entire the for (<1) low extremely also were large to urchin the of numbers due primarily SD12, and SD10, SD8, hauls (in terms of abundance) occurred at stations averaged from 473 to 4740 individuals. The largest station per abundance while 16, to 9 from ranged station per species of number mean the example, relatively uniform (Table were C.5 6.5,Appendix diversity and richness species while year, sc yellowchin single a on found also was tumor A v Invertebrate species richness and abundance have epresenting 42 species, were collected during 2005 Table6.4 mong stations and between surveys during the the during surveys between and stations mong re oe tm ( time over aried

ulpin. The copepod eye parasite

Luidia

Nymphon

Pleurobranchaea

foliolata ,

pictus Invertebrate Community

AppendixC.4

occurred on 2% of the Pacific Pacific the of 2% on occurred L.

sp, the sea stars

pixellae pictus

was the most abundant and most Parastichopus , the brittle star

iue 6.5 Figure

is typical of similar habitats . Diversity values Diversity pictus. L. .

). The white sea urchinseawhite The ).

california

Astropecten ). Annual species species Annual ). Ophiura

californicus Phrixocephalus

, and the sea the and ,

luetkenii,

verrilli ). For , the ,

Table 6.4 Table 6.5 Megabenthic invertebrate species collected in 12 Summary of megabenthic invertebrate community trawls in the PLOO region during 2005. Data for each parameters for PLOO stations sampled during 2005. species are expressed as: percent abundance (PA); Data are presented for cumulative (total) and mean frequency of occurrence (FO); mean abundance per number of species, abundance, diversity (H'), and occurrence (MAO). biomass (BM) (kg, wet weight); n=2 for each station.

Species PA FO MAO No. of Species Lytechinus pictus 92 100 1842 Station Total Mean Abund H’ Acanthoptilum sp 5 75 125 Allocentrotus fragilis 2 25 184 SD7 19 14 888 0.49 Astropecten verrilli <1 83 6 SD8 22 16 4740 0.07 Parastichopus californicus <1 83 4 SD10 17 11 3242 0.09 Luidia foliolata <1 75 3 SD12 14 9 2099 0.55 Pleurobranchaea californica <1 92 3 SD13 15 12 593 0.61 Sicyonia ingentis <1 42 3 SD14 12 9 473 0.44 Ophiura luetkenii <1 58 2 in abundance at various times. These fluctuations Metridium farcimen <1 42 2 Octopus rubescens <1 42 2 typically reflect changes in L. pictus, as well as Florometra serratissima <1 25 3 the urchin Allocentrotus fragilis, and the sea pen Luidia asthenosoma <1 25 3 Acanthoptilum sp to a lesser degree (Figure 6.6). Nymphon pixellae <1 50 1 The abundances of these 3 taxa is much lower at Platymera gaudichaudii <1 33 1 the 2 northern sites, and likely reflects differences Luidia armata <1 25 1 in the sediment composition (e.g., fine sands Ophiopholis bakeri <1 17 2 vs. mixed coarse/fine sediments). None of the Thesea sp B <1 25 1 observed variability in the invertebrate community Astropecten ornatissimus <1 8 3 Megasurcula carpenteriana <1 17 2 could be attributed to the discharge of wastewater Adelogorgia phyllosclera <1 17 1 from the PLOO. Cancellaria crawfordiana <1 8 2 Loligo opalescens <1 8 2 Loxorhynchus crispatus <1 8 2 SUMMARY AND CONCLUSIONS Ophiuroidea <1 8 2 PORIFERA <1 17 1 As in previous years, Pacific sanddabs continued Tritonia diomedea <1 8 2 to dominate fish assemblages surrounding the Acanthodoris brunnea <1 8 1 Amphichondrius granulatus <1 8 1 Point Loma Ocean Outfall during 2005. They Amphipholis squamata <1 8 1 were present in relatively high numbers at all Asterina miniata <1 8 1 stations. However, 2005 was unique in that 2 Crangon alaskensis <1 8 1 very large hauls of halfbanded rockfish were Henricia sp <1 8 1 collected near the outfall in January, which made Mediaster aequalis <1 8 1 this species the most abundant overall. Other Neosimnia barbarensis <1 8 1 characteristic, but less abundant species, included Ophionereis eurybrachiplax <1 8 1 Ophiothrix spiculata <1 8 1 Dover sole, longspine combfish, slender sole, Paguristes bakeri <1 8 1 English sole, pink seaperch, stripetail rockfish, Paguroidea <1 8 1 greenstriped rockfish, California tonguefish, Philine auriformis <1 8 1 roughback sculpin, greenspotted rockfish, and Pteropurpura macroptera <1 8 1 hornyhead turbot. Although the composition and Pyromaia tuberculata <1 8 1 structure of the fish assemblages varied among Rathbunaster californicus <1 8 1 stations, most differences were due to fluctuations Rossia pacifica <1 8 1 in Pacific sanddab populations. Spatangus californicus <1 8 1

68 10000 25 8000 Lytechinus pictus 20 6000 15 4000 10 2000 5 0

Species Richness Species 0 600 Acanthoptilum sp 6000 400 4000 200 2000 0 Abundance 0 200 150 Allocentrotus fragilis 92 93 94 95 96 97 98 99 00 01 02 03 04 05 100 South farfield Nearfield North farfield 50 SD7 SD10 SD13 0 Abundance SD8 SD12 SD14 100 80 Sicyonia ingentis Figure 6.5 60 Annual mean species richness (number of species) Abundance 40 and abundance (number of individuals) per PLOO 20 station of megabenthic invertebrates collected from 0 1992 through 2005; n=4 1992-2002, n=3 in 2003, and n=2 during 2004-2005. 50 40 Astropectin verrilli Assemblages of megabenthic invertebrates were 30 also dominated by a single prominent species, the 20 white sea urchin Lytechinus pictus. Other common 10 species included the sea pen Acanthoptilum sp, the 0 92 93 94 95 96 97 98 99 00 01 02 03 04 05 sea stars Astropecten verrilli and Luidia foliolata, the brittle star Ophiura luetkenii, the sea cucumber Nearfield Parastichopus californicus, the sea hare South farfield North farfield Pleurobranchaea california, and the sea spider SD7 SD10 SD13 Nymphon pixellae. Although megabenthic community SD8 SD12 SD14 structure varied between sites, these assemblages Figure 6.6 were generally characterized by low species richness Annual mean abundance (number of individuals) per and diversity. Abundance and biomass proportional to PLOO station for the five most abundant megabenthic the number of L. pictus collected in each haul. invertebrate species collected from 1992 through 2005; n=4 1992-2002, n=3 in 2003, and n=2 during 2004-2005. Analyses of 15 years of fish data from July surveys demonstrated that spatial and temporal differences are located in slightly shallower (~95–100 m) in the fish assemblages were not associated with sediments that are poorly sorted (i.e., of varied the PLOO discharge. Instead, changes in these sizes), and are subject to influences from dredge assemblages seem to be related oceanographic spoils disposal. Station SD7 is located near LA-4, events (e.g., El Niño conditions) or location. a the defunct dredge spoils disposal site, and SD8 For example, the southern farfield stations, SD7 is located near LA-5, an active disposal site. Both and SD8, frequently group apart from the outfall locations have coarse sediments and are subject and the northern outfall stations. These stations to disturbance (see Chapter 4, City of San Diego

69 2006). Additionally, species collected at station Department, Environmental Monitoring and SD12 tended to differ (at least on occasion) Technical Services Division, San Diego, CA. from the other nearfield station (SD10) and the northern farfield stations. This may be because of City of San Diego. (in prep). EMTS Division its location just north of the outfall, where extra Laboratory Quality Assurance Project Plan. relief from ballast rock in the area, or the outfall City of San Diego Ocean Monitoring Program, pipe may be providing refuge for resident fishes Metropolitan Wastewater Department, against the prevailing northward currents. Environmental Monitoring and Technical Services Division, San Diego, CA. Overall,resultsofthetrawl surveys conductedin2005 provide no evidence that the discharge of wastewater Clarke, K.R. (1993). Non-parametric multivariate from the Point Loma Ocean Outfall affected fish analyses of changes in community structure. or megabenthic invertebrate communities in the Aust. J. Ecol., 18: 117–143. region during the year. Although highly variable, patterns in the abundance and distrubtion of species Cross, J.N., and L.G. Allen. (1993). Chapter were similar at stations located near the outfall and 9. Fishes. In: Dailey, M.D., D.J. Reish, further away. Changes in these communities that have and J.W. Anderson, eds. Ecology of the occurred over time appear to be more likely due to Southern California Bight: A Synthesis and natural factors such as changes in water temperature Interpretation. University of California Press, associated with large scale oceanographic events (El Berkeley, CA. p. 459–540. Nino), sediment conditions, and the mobile nature of many of the species collected. Finally, the general Cross, J.N., J.N. Roney, and G.S. Kleppel. (1985). absence of disease or physical abnormalities on local Fish food habitats along a pollution gradient. fishes suggests that populations in the area continue California Fish and Game, 71: 28–39. to be healthy. Helvey,M.,andR.W.Smith.(1985).Influenceofhabitat structureonthefishassemblagesassociatedwith LITERATURE CITED two cooling-water intake structures in southern California. Bull. Mar. Sci., 37: 189–199. Allen,M.J.(1982).Functionalstructureofsoft-bottom fishcommunitiesofthesouthernCaliforniashelf. Karinen, J.B., B.L. Wing, and R.R. Straty. (1985). Ph.D. dissertation. University of California, San Records and sightings of fish and invertebrates Diego. La Jolla, CA. 577 pp. in the eastern Gulf of Alaska and oceanic phenomena related to the 1983 El Niño event. Allen, M.J., S.L. Moore, K.C. Schiff, S.B. Weisberg, In: Wooster, W.S. and D.L. Fluharty, eds. El D. Diener, J.K. Stull, A. Groce, J. Mubarak, Niño North: El Niño Effects in the Eastern C.L. Tang, and R. Gartman. (1998). Southern Subarctic Pacific Ocean. Washington Sea California Bight 1994 Pilot Project: Chapter V. Grant Program. p. 253–267. DemersalFishesandMegabenthicInvertebrates. Southern California Coastal Water Research Murawski, S.A. (1993). Climate change and Project, Westminister, CA. 324 pp. marine fish distribution: forecasting from historical analogy. Trans. Amer. Fish. Soc., City of San Diego. (2006). Annual Receiving 122: 647–658. Waters Monitoring Report for the South Bay Ocean Outfall (South Bay Water Reclamation Warwick, R.M. (1993). Environmental impact Plant), 2005. City of San Diego Ocean studies on marine communities: pragmatical Monitoring Program,MetropolitanWastewater considerations. Aust. J. Ecol., 18: 63–80.

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