consume detritus, small shrimp, and other small 

 crustaceans. As suggested by its common name, 

 the bay anchovy, A. mitchilli, is common in 

 brackish waters, whereas .-1. hepsetus is charac- 

 teristic ot fully saline environments. Along with 

 silversides, the anchovies are the most numerous 

 of the small baitfishes found in shallow waters 

 along the North Carolina coast. 



Like anchovies, juvenile silversides {Menidia 

 menidta, M. beryllina, Membras martinica) are 

 also planktivores, feeding largely on zooplankton 

 (Darnell 1958). Silversides also show some habitat 

 segregation along a salinity gradient, with M. men- 

 idia in fully saline waters and M. beryllina in 

 brackish areas. As adults, silversides become more 

 omnivorous, feeding on detritus and polychaetes, 

 small shrimp, amphipods, and other small crusta- 

 ceans. This omnivorous diet closely resembles the 

 diet of another type of baitfish common on inter- 

 tidal flats, the killifishes {Fundulus majalis, F. 

 heteroclitus, Cyprinodon variegatus). Where 

 deeper tide pools are found on the flats, F. heter- 

 oclitus and C. variegatus are year-round residents 

 of shallow waters in North Carolina, although 

 most individuals spend the winters in deep-water 

 habitats. Fundulus majalis tends to be found in 

 sandy sediments and in high salinities, while F. 

 heteroclitus prefers muddier habitats and toler- 

 ates lower salinities. Some authors have suggested 

 that F. heteroclitus feeds only in salt marshes at 

 high tide (Vince et al. 1976). Even if F. heter- 

 oclitus also feeds on unvegetated tidal flats, F. 

 majalis is by far the most important killifish in 

 the unvegetated intertidal flat environment. 



The mullets [Mugil cephalus and M. curema) 

 represent the last baitfish group of importance 

 remaining to be mentioned. Mugil cephalus, the 

 striped mullet, is by far the most abundant mul- 

 let in North Carolina. Mullets are almost pure de- 

 tritivores, taking mouthfuls of surface sediments 

 and digesting what they can. Juvenile mullets 

 grow up in shallow waters of sounds, estuaries, 

 and lagoons along the North Carolina coast. In 

 the fall, young mullets form massive schools 

 which migrate south. This mullet migration coin- 

 cides with what is called a mullet blow in North 

 Carolina, a shift of the winds into the north in- 

 duced by the passage of a cold front. Schools of 

 migrating mullets, with each individual almost 

 geometrically positioned and equally spaced from 

 its nearest neighbors in the school, are a common 



sight in the sounds of North Carolina during Sep- 

 tember and October. Although many mullets join 

 this southward migration in the fall, mullets are 

 still common in North Carolina's estuaries during 

 the winter. Mugil cephalus is also known as the 

 jumping mullet for its tendency to leap from the 

 water, although the less common white mullet {M. 

 curema) probably jumps also. Smaller mullets 

 clearly jump as a response to being disturbed or 

 chased by predators. Larger mullets also jump, 

 and some authors have suggested that such 

 leaping may help remove external parasites. 



Other fishes occasionally consume detritus 

 from the surface of North Carolina's intertidal 

 flats. Of these, the pinfish (Lagodon rhomboides) 

 is the most common. The pinfish is generally con- 

 sidered a grass-bed species when it occurs in estu- 

 aries. Its normal diet encompasses the encrusting 

 fauna and flora found on firm substrates such as 

 grass blades. Yet pinfish are so universally abun- 

 dant in North Carolina's sounds and estuaries that 

 they can be found feeding on all types of bottoms 

 including unvegetated intertidal flats. The filefish 

 [Monacanthus hispidus) feeds in a similar fashion 

 in grass beds, and like the pinfish, can also be 

 found feeding over intertidal flats. The filefish is 

 much less abundant than pinfish, which is the 

 most characteristic benthic feeder in North Caro- 

 lina's estuaries. 



4.3 PREDATORS ON BENTHIC FAUNA, 



MOBILE EPIBENTHIC INVERTEBRATES, 

 AND FISHES 



The vast majority of the fish species listed in 

 Tables 2 and 3 are predators either (1) on the 

 benthic infauna and small epibenthos or (2) on 

 fishes and larger epibenthic animals. These two 

 trophic categories include two groups of fishes 

 which, along with some of the smaller baitfishes 

 discussed above, are perhaps the most characteris- 

 tic fishes of intertidal flat habitats worldwide: 

 (1) the rays and skates and (2) the flatfishes. 



Rays are prominent on intertidal flats around 

 the world. They dig pits in the sediments in their 

 search for clams and other buried infauna. 

 Flapping their "wings," the fleshy parts of their 

 extensive pectoral fins, enables rays to excavate 

 substantial craters. The roots of marine grasses 

 help to inhibit excavations by rays in the same 

 way that they interfere with the activities of blue 



43 



