Review of the book titled "Ecology of Estuarine Fishes: Temperate Waters of the Western North Atlantic" by Kenneth Able and Michael Fahay.
Throughout, the authors emphasize the transitional nature of estuaries and the diversity of life stage of estuaries by fish. The authors note that the majority of estuarine species are transient (not even including rare strays), with a minority of species resident in estuaries for their entire life. The authors distinguish ten different patterns of life history, based on spawning location and season and estuarine use by different life stages, and there is considerable variation among species within groups.
The book has two sections, an 11-chapter overview of ecological topics and accounts of the life history of 93 species. The geographic scope of the book is the mid-Atlantic Bight, Cape Cod to Cape Hatteras (these are the temperate waters of the title), but the heart of the work is Great Bay, where Able and Fahay have conducted much of their research. There are references to habitat use outside the mid-Atlantic Bight, but usually no detailed summary of data from these areas. There are some data from other estuaries in the Bight. There is little discussion of how the very different topographies of Great Bay and other estuaries (e.g., the Delaware or Hudson) may affect movements of life stages between fresh water, estuary, and ocean.
The initial chapters provide introductory material and syntheses of topics across all fish species. These chapters cover broad topics and cite an extensive literature in both tabular and text formats. The first four chapters are introductory, with a formal introduction, a summary of the physical and chemical oceanography of the study area, including currents as they may affect fish dispersal, an outline (approach chapter) of the various individual studies in terms of spatial and temporal scope and gear, with more detailed methods on new material (patterns of scale formation in postlarval fish), and an introduction to the temperate ichthyofauna. The following five chapters parallel sections of the individual species accounts, with sections on reproduction and development, larval movement and growth, habitat use, trophic relationships, and migrations. These chapters are informative, but they often read more like short papers than reviews, with introductory literature reviews and results of specific studies. The introductory sections often have broad statements and a number of citations, but little detail on individual studies or explanation for differences among different studies. Most detail is reserved for work from Able's lab. For example, discussions of methods of larval transport are summarized in less than a quarter of a page (in the chapter on development, rather than the chapter on larval supply), while several pages present results of larval sampling programs in Great Bay. A section on "Environmental Effects on Larval Supply" contains two introductory paragraphs and about four pages on the authors' study of effects of coastal upwellings on larval ingress to estuaries (apparently unpublished). These chapters also include several large tables which will serve as very useful references: a checklist of species; ranked abundances of larvae at Little Inlet from 1989-2006; life history characteristics, spawning location, and development; occurrence of different life stages in specific estuaries; average larval abundance in five estuaries (Little Egg Inlet to Beaufort Inlet; and a matrix of important foods of young-of-year of different species. The bibliography cites about 1050 references, almost all to the primary literature; no attempt is made to judge or review any gray literature.
In the last topic chapter, Future Directions, the authors discuss both new concepts and new techniques to apply to old concepts. This chapter mentions many of the types of studies that I missed in the rest of the text: telemetry, otolith microchemistry, metapopulation dynamics and inter-estuarine movements, stable isotope analyses, trophic cascades and biotic interactions, behavioral variability within species (e.g., among individuals, contingents, and cohorts), effects of parasites and diseases, use of remote sensing and continuous in situ monitoring of physico-chemical variables, and investigation of various anthropogenic effects. They also note that basic life history information is missing for many species. Some things not on the list (or in the text) which seem relevant: genetic analyses (for understanding spatial structure of population, adaptation, etc.), aging, and modeling (population, ecosystem, oceanographic, climatic, etc.).
Throughout the text, the authors use sidebars to present anecdotal observations, preliminary analyses, and speculative hypotheses. For example, these include notes on oophagy by eels, consumption of eel leptocephali by bluefish, and taxonomy of Cyprinodon. It is noteworthy that the authors are able to maintain consistent long term sampling programs while keeping an eye out for unusual natural history observations.
The writing is generally clear and straight-forward. The various topics of these chapters are closely related, and organization of the massive amount of material is sometimes problematic. I've had to search around several chapters to find or re-find a particular discussion, figure or table of interest. The parallel structure of overview and species accounts covering the same topics builds in a certain amount of duplication. There is further duplication of some material. For example, a possible relationship between glass eel abundance and freshwater inflows is mentioned repeatedly: as a sidebar, in the section on environmental effects on larval supply, as illustration of potential effects of climate change via changes in precipitation, and briefly in the eel species account.
The penultimate overview chapter is on climate change, noting potential effects of changes in seasonal temperatures, precipitation and sea level. This chapter provides data on trends in water temperatures and analyses of trends in abundance over the 1989-2006 Great Bay sampling programs. Abundance and species richness of larvae of southern species increase over the period (abundance mainly from 2003-2006 and richness mainly in the 1990's), while northern species showed a different patterns, with an apparent broad peak in the 1990's. The chapter uses a model for Atlantic croaker (Microponias undulates) abundance as related to winter temperatures and overwinter mortality as a case study of potential effects of climate change.
In the individual species accounts, the authors include a picture of a juvenile of each species, a conceptual graph of the seasonal use of the estuary and ocean by life stages, information on egg and larval appearance (but rightly cite Fahay's 2007 work for details), monthly length-frequency histograms keyed to estuarine and oceanic occurrence, graphs of temporal trends of abundance of larvae (for 37 species) and sometimes juveniles, season-by-year graphs of abundance, maps of occurrence of YOY and older juveniles in the Bight (in place of the maps of larval occurrence in AF98), and discuss ecology of different life stages. The quantitative data derive from the extensive field work of Able and students in Great Bay and the adjacent Atlantic, and the NOAA surveys for the distributional information over the entire Bight. The temporal trend graphs are exciting, especially since they include non-commercial species for which relatively little other trend data exist. The recent book includes 24 accounts that were not in AF98, covers a larger range of sizes of each species, includes a great amount of new data (for example, length frequency histograms for bay anchovy in the new book are based on over 400,000 specimens, in comparison to 14,000 in AF98), and presents temporal trend information.
I have a major criticism of the length-frequency (actually log-transformed cpue) histograms. These show size distributions of fish in different months, with stacked bars to indicate collection in the bay and ocean. Unfortunately, these give a false sense of quantitative certainty. They combine data from many collecting techniques, with a range in size selectivities from small fish bias of plankton nets to larger fish bias of trawls. While use of a variety of gears should give a better picture of size distribution than a single technique with low efficiency for many sizes, construction of accurate histograms is tricky, especially when sample size differs among gear types. It's not explained how catch rates per unit effort are combined across very different gear types. The figure legends indicate how many samples by each technique are represented in all the graphs, but there is no further breakout of data. With no information on the size distribution of collections of each species by various techniques, the graphed size distributions probably give only a general impression of abundance of various sizes. For some species, some modes are narrow, suggesting collection by a single technique, but many distributions are broad and relatively flat. There is no way to know whether this represents the actual distribution or is an artifact of different size contributions by different gears. Since fish may have been collected by different gear in the bay and ocean, the relative size of the ocean and bay bars for any size are difficult to interpret. A figure in the introduction shows overall size distributions by some of the gears, demonstrating modal differences with considerable overlap. The issue of gear size selectivity is mentioned in the text, but there is no discussion of effects on sampling results. In AF98, the authors' note that their goal was to effectively sample every size of fish present at any time, but they don't discuss how this use of multiple gear affects their analysis in either work. The graphs already distinguish two types of data, (estuarine or oceanic occurrence by paired bars), so adding another level to differentiate catches by gear could simultaneously make the graphs more confusing and more meaningful.
In the species accounts, much of the explanatory text on early life stages is taken directly from AF98. This is occasionally misleading. For example, reading that American shad showed declines in the early part of the century led me to expect a discussion of the recent controversy about shad trends, until I realized the text was a holdover from AF98 referring to the early 20th Century. Species accounts have been updated, although the numbers of citations after 1997 to papers outside of Able's lab seem somewhat sparse (for example, I counted about 11 for striped bass, 7 for weakfish, and one for shortnose sturgeon). Citations to AF98 are uneven; sometimes, AF98 is given as a citation, even when the new text contains the same information as the earlier text, while most uses of earlier text are not cited. I had relatively few quibbles with the statements in the accounts; many of these related to current conditions in the Delaware estuary.
With the exception of the chapter on potential effects of climate change and a section on anthropogenic influences, the book emphasizes "natural" patterns. The reader will get little sense that the species discussed have been the center of long controversies on overfishing, regulation, commercial versus recreational fisheries, bycatch, cooling water mortality, contamination, and predator/prey interactions. The section on anthropogenic influences is about three pages long, which gives most attention to effects of piers and Phragmites, issues in which the authors have been involved. For example, with respect to dredging, there is a statement that dredging is one of the most common human influences on estuaries, a statement that relatively little is known of effects of dredging, and a statement summarizing Able's work on effects of dredging of a boat basin on mummichogs. Concerns and research about deepening of the Delaware Estuary navigation channel or about PCBs and dredging of the Hudson River are not mentioned. This book will provide the foundations for understanding where, when and at what stages various species might be vulnerable to various human impacts, but the reader will need to look elsewhere to understand these issues and potential effects on long term trends in abundance. Similarly, the book is distinctly salty. While occurrence of diadromous fish in freshwater is mentioned in the accounts, there is little detail on life history of these fish in freshwater.
This book will serve as an important reference on a variety of aspects of estuarine fishes of the area and as a basis for comparison with other areas. The introductory chapters will provide excellent background and introduction to parts of the literature. For students, thesis topics virtually drip from the pages. I think most readers will find something new in it. This is true even if the reader is familiar with all the papers from Able's lab (assuming this is possible), since it contains unpublished material and synthesis. In short, this book will often be the first place I look for information on these fishes. It won't he the last, but first is pretty good.
DR. RICHARD J. HORWITZ
FISHERIES, THE ACADEMY OF NATURAL SCIENCES OF DREXEL UNIVERSITY, 1900 BENJAMIN FRANKLIN PARKWAY, PHILADELPHIA, PA 19103
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|Author:||Horwitz, Richard J.|
|Publication:||Bulletin of the New Jersey Academy of Science|
|Article Type:||Book review|
|Date:||Sep 22, 2011|
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