Comparisons of fauna among natural and transplanted eelgrass Zostera marIna meadows: criteria for mitigation

Abstract

Numencal abundance, species composition and size of fish and shrimp were compared among (1) unvegetated, (2) transplanted (3) recently seed-colonized and (4) matule, natural eelgrass habitats to determine the equivalence of transplanted eelgrass beds to their natural counterparts In general, fish and shrimp were most abundant in mature natulal eelgrass habitats and least abundant in unvegetated habitats We developed a vector-graphical analysls that shows eplbenthic faunal abundance to be closely coupled with eelgrass bed development In an area where transplants performed poorly, the faunal component had a different composition and significantly lower numerical abundance In companson to natural beds Fauna1 abundance and composition in a 1 9-yr-old transplanted bed and a 6-mo-old seed-developed bed were indistinguishable from mature natural eelgrass beds Our data Indicate that recruitment of fish and shrimp to eelglass habitats established through transplantahon can occur in time, though not as rapidly as with naturally-seeded beds Area1 shoot density may serve as an inexpensive diagnostic parameter of functional equivalence for most resident macroeplfauna Abundance data need to be interpreted through functional mechanisms such as predation which act to produce the observed abundances in older to separate habitat function from dysfunchon Restored seagrass habitats have the potential to make substantial contributions to fish and shrimp production provided the habitats persist

Seascape ecology of coastal biogenic habitats: advances, gaps, and challenges

“…When time has explicitly been incorporated as an explanatory variable, usually strong interactions have been found between spatial pattern metrics and time (Hovel & Lipcius 2001, Johnson & Heck 2006. For instance, edge effects in seagrasses may show inconsistent patterns among months (Fonseca et al 1990, Horinouchi 2009, and strong diurnal variation of fish abundance may break down associations between fish and seagrass seascape configuration (Jackson et al 2006a). In addition, inconsistent effects of seascape configuration demonstrated by interactions between time and patch size appear to be common across species (fish and decapods) and habitats (seagrass meadows, oyster reefs, and coral reefs) (Molles 1978, Eggleston et al 1998, Jelbart et al 2006, Johnson & Heck 2006.…”

Development of planted seagrass beds in Tampa Bay, Florida, USA. II. Faunal components

“…Entry level = 0.05 and retent~on = 0.10 (p values). Only vanables that were retained are shown Fauna1 composition: Animal composition was compared among pairs of treatments by computing percentage similarity (Whittaker & Fairbanks 1958), as used by Holmquist et al (1989) and Fonseca et al (1990) Table 2). The and T. testudinum 5.9 species m-' over the course of numbers of taxa m-' in all treatments are shown in the study; Fig.…”

“…Three randomly selected 1 m' locations (replicates) were chosen for plant and animal sampling within each plot at each sample time. Upon completion of shoot counts at each location, 1 X 1 m dropnets similar to those used by Fonseca et al (1990) were deployed directly over each of the replicate areas. The nets were supported by 4 poles with release pins which were triggered from -10 m away.…”

“…These studies generally conclude that some functions of seagrass beds can be restored as the result of planting operations (but see Smith et al 1989). These few studies, some of which experienced poor planting success (Fonseca et al 1990) or lacked control comparisons (McLaughlin et al 3.983), do not constitute sufficient data upon which to make many management decisions regarding the efficacy of seagrass restoration or mitigation. In addition, requiring data collection of a wide variety of seagrass bed functions as success criteria under mitigation can be difficult to enforce except in very large, expensive projects (pers.…”

“…The resource value of natural seagrass beds has been well documented (Zleman 1982, Phillips 1984, Thayer et al 1984, Hoffman 1986, Larkum et al 1989, however there have been few studies to evaluate the assumption that restoring or creating seagrass beds provides a concomitant recovery of commercially and recreationally valuable animal species and/or their food sources (Nessmith 1980, Homziak et al 1982, McLaughlin et al 1983, Smith et al 1989, Fonseca et al 1990). These studies generally conclude that some functions of seagrass beds can be restored as the result of planting operations (but see Smith et al 1989).…”