Relationships between coastal wetland habitat and young of the year fish community characteristics, distribution, and growth.

摘要

Although wetlands are important habitat for the early life history stages of many fish species, little is known about how wetland habitat characteristics affect young of the year (YOY) fish. This study examines the effect of wetland habitat characteristics on YOY fish community composition, distribution, and growth at two spatial scales. At the macrohabitat scale, relationships between habitat characteristics (e.g. habitat complexity, wetland area, and percent cover of different vegetation types) and characteristics of the YOY fish community, including fish abundance, species richness, diversity, species composition, and fish growth, were examined. At the microhabitat scale, relationships between habitat characteristics (e.g. vegetation type and density, water depth, dissolved oxygen, and turbidity) and the distribution of YOY bluegill, banded killifish, yellow perch, and spottail shiners were examined. Additionally, two enclosure experiments were conducted to evaluate the growth of YOY bluegill under different microhabitat conditions. Young of year fish were responding to changes in wetland habitat characteristics at the macrohabitat and microhabitat scale. Habitat characteristics that had the largest influence on YOY fish included the abundance and type of wetland vegetation, and water depth. The amount of vegetation influenced species richness, diversity, community composition, and fish growth at the macrohabitat scale. The type of vegetation present influenced the presence or absence of banded killifish, and the presence or absence and growth of bluegill at the microhabitat scale. Wetlands that had areas of deeper wetland habitat had a higher diversity of YOY fish, and faster growth rates of bluegill. Within wetland areas, the presence or absence of YOY fish from three of the four fish species examined was positively correlated with increasing water depth within the 0 to 100 cm range sampled. Other macrohabitat characteristics that showed strong relationships with the YOY fish community included habitat complexity and the presence of islands, sand bars, or gravel bars. At the microhabitat scale, the presence or absence of resident wetland species was correlated with changes in the physical structure of the habitat, while the distribution of transient wetland species was correlated with changes in water quality. Results of the enclosure experiments indicated that YOY bluegill fed on both macroinvertebrates and zooplankton when confined to emergent vegetation, submersed vegetation, or open water habitats; however they consumed more zooplankton and less macroinvertebrates in open water than in vegetated habitats. Bluegill growth was influenced by the density of YOY fish as well as the type of vegetation present, growing faster at low densities, and in areas of submersed vegetation.