. Bulletin. Science. MISSION BAY BENTHOS 141 A) I Total Macrofauna (#+l/m^) 0000-: â Musculista senhousia (#+ l/m^) XS. â - - â Number of Species (# / station) 1 1000-1 V ""X^^ J ⢠» ⢠t ' t â % ⢠t ⢠\ ⢠« t t 100 â¢: 10- 1- « % % % % % 4 t % % ^ , A i" » ⦠. » / » ⢠# ⢠. » / ⢠⢠'. , V . V ... â â V â \ \ â t â t â t 1 \ 1 ⢠âr â - -%â « . t , % . % â % ' » ' « ⢠t ⢠1 ⢠⢠1 â 1 ⢠1 1 » t % ⢠t t . â '*'' 1 ⢠B) 10000-1 IOOOt g 100- 10 Deposit Feeders (#+l/m^) Suspension Feeders (#+l/m^). I I I 1970 1975 T 1 1 T 1980 1 1 1 r 1985 âIâ^ 19
. Bulletin. Science. MISSION BAY BENTHOS 141 A) I Total Macrofauna (#+l/m^) 0000-: â Musculista senhousia (#+ l/m^) XS. â - - â Number of Species (# / station) 1 1000-1 V ""X^^ J ⢠» ⢠t ' t â % ⢠t ⢠\ ⢠« t t 100 â¢: 10- 1- « % % % % % 4 t % % ^ , A i" » ⦠. » / » ⢠# ⢠. » / ⢠⢠'. , V . V ... â â V â \ \ â t â t â t 1 \ 1 ⢠âr â - -%â « . t , % . % â % ' » ' « ⢠t ⢠1 ⢠⢠1 â 1 ⢠1 1 » t % ⢠t t . â '*'' 1 ⢠B) 10000-1 IOOOt g 100- 10 Deposit Feeders (#+l/m^) Suspension Feeders (#+l/m^). I I I 1970 1975 T 1 1 T 1980 1 1 1 r 1985 âIâ^ 1990 1995 Year Fig. 8. Station B from 1970-1996. A) Average total densities (number m"^), total number of Musculista senhousia (number m^), and species richness (number per station). B) Average densities of suspension and deposit feeders characteristic of the reported flushing regimes (Fairey et al. 1997). In the back bay, combustible organic matter is high () and sediment grain sizes are small (78-93% fine sediments < 63fxm). Nearer the entrance of the bay, there is less organic matter () and grain sizes are larger (33% fines) (Fairey et al. 1997). Gradients in physical conditions such as those reported in Mission Bay can affect benthic assemblages, and organic enrichment (both natural and anthropo- genic) are particularly important in structuring these communities (Pearson and Rosenberg 1978; Long and Chapman 1985; Jensen 1986; Brown et al. 1987; Friligos and Zenetos 1988; Help 1995). Typically, communities in areas with low flushing and sources of organic input have low diversities and are dominated by opportunistic species (Pearson and Rosenberg 1978; Weston 1990). Such char- acteristics are found at Station E (nearest the mouth of Tecolote Creek), where species richness is low and the fauna is dominated by the exotic Musculista sen- housia (Table 1; Fig. 3). Nearer the front of
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