Abundance, condition, and diet of juvenile Pacific ocean perch (Sebastes alutus) in the Aleutian Islands

T he relative value of pelagic habitat for three size classes of juvenile Pacific ocean perch (Sebastes alutus) was investigated by comparing their abundance and condition in two areas of the Aleutian Islands. Diet, zooplankton biomass, and water column temperatures were examined as potential factors affecting observed differences. Juvenile Pacific ocean perch abundance and condition, and zooplankton biomass varied significantly between areas, whereas juvenile Pacific ocean perch diet varied only by size class. Observed differences in fish condition may have been due to the quantity or quality of pelagic prey items consumed. For the delineation of essential demersal fish habitat, important ecological features of the pelagic habitat must therefore be considered.

Decline in condition of northern bluefin tuna (Thunnus thynnus) in the Gulf of Maine

The northern bluefin tuna (Thunnus thynnus) is a highly mobile apex predator in the Gulf of Maine. Despite current stock assessments that indicate historically high abundance of its main prey, Atlantic herring (Clupea harengus), commercial fishermen have observed declines in the somatic condition of northern bluefin tuna during the last decade. We examined this claim by reviewing detailed logbooks of northern bluefin tuna condition from a local fishermen’s cooperative and applying multinomial regression, a robust tool for exploring how a categorical variable may be related to other variables of interest. The data set contained >3082 observations of condition (fat and oil content and fish shape) from fish landed between 1991 and 2004. Energy from stored lipids is used for migration and reproduction; therefore a reduction in energy acquisition on bluefin tuna feeding grounds could diminish allocations to growth and gamete production and have detrimental consequences for rebuilding the western Atlantic population. A decline in northern bluefin tuna somatic condition could indicate substantial changes in the bottom-up transfer of energy in the Gulf of Maine, shifts in their reproductive or migratory patterns, impacts of fishing pressure, or synergistic effects from multiple causes.

Length-weight relationship and relative condition of Heterobranchus longifilis (Valenciennes) from Idodo River, Nigeria

Length-weight relationship parameters of Heterobranchus longifilis males, females and combined sexes are given. The samples were collected from Idodo River, with size ranging from 123 mm total length, L, to 936 mm L. The values obtained for the mean L by sex show that males were significantly (p<0.05) larger than females. The results show that the slope (b) is significantly (p<0.05) below 3.0 for the male, female and pooled sample. The species exhibit a negative allometric growth pattern. The relative condition of fish shows seasonal variation, with females generally being in better condition than the males.

Distribution, feeding condition, and growth of Japanese Spanish mackerel (Scomberomorus niphonius) larvae in the Seto Inland Sea

Distribution of eggs and larvae and feeding and growth of larvae of Japanese Spanish mackerel (Scomberomorus niphonius) were investigated in relation to their prey in the Sea of Hiuchi, the Seto Inland Sea, Japan, in 1995 and 1996. The abundance of S. niphonius eggs and larvae peaked in late May, corresponding with that of clupeid larvae, the major prey organisms of S. niphonius larvae. The eggs were abundant in the northwestern waters and the larvae were abundant in the southern waters in late May in both years, indicating a southward drift during egg and yolksac stages by residual f low in the central part of the Sea of Hiuchi. Abundance of clupeid larvae in southern waters, where S. niphonius larvae were abundant, may indicate a spawning strategy on the part of first-feeding S. niphonius larvae to encounter the spatial and temporal peak in ichthyoplankton prey abundance in the Seto Inland Sea. Abundance of the clupeid larvae was higher in 1995 than in 1996. Feeding incidence (percentage of stomachs with food; 85.3% in 1995 and 67.7% in 1996) and mean growth rate estimated from otolith daily increments (1.05 mm/d in 1995 and 0.85 mm/d in 1996) of S. niphonius larvae in late May were significantly higher in 1995. Young-of-the-year S. niphonius abundance and catch per unit of fishing effort of 1-year-old S. niphonius in the Sea of Hiuchi was higher in 1995, indicating a more successful recruitment in this year. Spatial and temporal correspondence with high ichthyoplankton prey concentration was considered one of the important determinants for the feeding success, growth, and survival of S. niphonius larvae.

The ecological condition of estuaries in the Gulf of Mexico

This document is intended for use by scientists and other citizens concerned with the ecological condition of estuaries, as well as by managers and lawmakers interested in the sustained use of estuaries for commercial and recreational purposes. It also addresses public concerns about the aesthetic quality of coastal areas vital to tourism and recreation. By producing this report on the ecological condition of estuaries in the Gulf of Mexico, we have taken one step in assessing the health of this environmental resource. We have produced an environmental report card to be used as a guide in the evaluation of management decisions and research directions. This report is organized in three parts: (1) an introduction that gives background information on the Gulf of Mexico, estuarine ecology, and the factors that impact estuaries in the gulf, (2) the main section on priority ecological indicators used to measure the condition of estuaries in the gulf and (3) an ecological report card that summarizes the data on ecological indicators and provides a rating of the condition of estuaries in each gulf state and for gulf estuaries overall. Many of the ratings were based on the percent area of estuaries in each state exhibiting degraded or adverse levels of an indicator.

Effects of pot fishing on the physical condition of snow crab (Chionoecetes opilio) and southern Tanner crab (Chionoecetes bairdi)

The effects of commercial fishing with crab pots on the physical condition of the snow crab (Chionoecetes opilio) and southern Tanner crab (C. bairdi) were investigated in the Bering Sea and in Russian waters of the Sea of Okhotsk. In crabs that were subjected to pot hauling, the presence of gas embolism and the deformation of gill lamellae were found in histopathological investigations. Crab vitality, which was characterized subjectively through observation of behavioral responses, depended on not only the number of pot hauls but also the time between hauls. Immediately after repeated pot hauls at short time intervals (≤3 days), we observed a rapid decline in vitality of crabs. When hauling intervals were increased to >3 days, the condition of crabs did not significantly change. After repeated pot hauls, concentration of the respiratory pigment hemocyanin ([Hc]) was often lower in the hemolymph of crabs than in the hemolymph of freshly caught animals. Our research indicated that changes in [Hc] in crabs after repeated pot hauls were caused by the effects of decompression and not by starvation of crabs in pots or exposure of crabs to air. We suggest that the decrease in [Hc] in hemolymph of snow and southern Tanner crabs was a response to the adverse effects of decompression and air-bubble disease. The decrease in [Hc] in affected crabs may be a result of mechanisms that regulate internal pressure in damaged gills to optimize respiratory circulation.

Using measurements of muscle cell nuclear RNA with flow cytometry to improve assessment of larval condition of Walleye Pollock (Gadus chalcogrammus)

Nuclear RNA and DNA in muscle cell nuclei of laboratory-reared larvae of Walleye Pollock (Gadus chalcogrammus) were simultaneously measured through the use of flow cytometry for cell-cycle analysis during 2009–11. The addition of nuclear RNA as a covariate increased by 4% the classification accuracy of a discriminant analysis model that used cell-cycle, temperature, and standard length to measure larval condition, compared with a model without it. The greatest improvement, a 7% increase in accuracy, was observed for small larvae (<6.00 mm). Nuclear RNA content varied with rearing temperature, increasing as temperature decreased. There was a loss of DNA when larvae were frozen and thawed because the percentage of cells in the DNA synthesis cell-cycle phase decreased, but DNA content was stable during storage of frozen tissue.

Ecological condition of coastal ocean and estuarine waters of the U.S. South Atlantic Bight: 2000-2004

In March-April 2004, the National Oceanic and Atmospheric Administration (NOAA), U.S. Environmental Protection Agency (EPA), and State of Florida (FL) conducted a study to assess the status of ecological condition and stressor impacts throughout the South Atlantic Bight (SAB) portion of the U.S. continental shelf and to provide this information as a baseline for evaluating future changes due to natural or human-induced disturbances. The boundaries of the study region extended from Cape Hatteras, North Carolina to West Palm Beach, Florida and from navigable depths along the shoreline seaward to the shelf break (~100m). The study incorporated standard methods and indicators applied in previous national coastal monitoring programs — Environmental Monitoring and Assessment Program (EMAP) and National Coastal Assessment (NCA) — including multiple measures of water quality, sediment quality, and biological condition. Synoptic sampling of the various indicators provided an integrative weight-of-evidence approach to assessing condition at each station and a basis for examining potential associations between presence of stressors and biological responses. A probabilistic sampling design, which included 50 stations distributed randomly throughout the region, was used to provide a basis for estimating the spatial extent of condition relative to the various measured indicators and corresponding assessment endpoints (where available). Conditions of these offshore waters are compared to those of southeastern estuaries, based on data from similar EMAP/NCA surveys conducted in 2000-2004 by EPA, NOAA, and partnering southeastern states (Florida, Georgia, South Carolina, North Carolina, Virginia) (NCA database for estuaries, EPA Gulf Ecology Division, Gulf Breeze FL). Data from a total of 747 estuarine stations are included in this database. As for the offshore sites, the estuarine samples were collected using standard methods and indicators applied in previous coastal EMAP/NCA surveys including the probabilistic sampling design and multiple indicators of water quality, sediment quality, and biological condition (benthos and fish). The majority of the SAB had high levels of DO in near-bottom water (> 5 mg L-1) indicative of "good" water quality. DO levels in bottom waters exceeded this upper threshold at all sites throughout the coastal-ocean survey area and in 76% of estuarine waters. Twenty-one percent of estuarine bottom waters had moderate levels of DO between 2 and 5 mg L-1 and 3% had DO levels below 2 mg L-1. The majority of sites with DO in the low range considered to be hypoxic (< 2 mg L-1) occurred in North Carolina estuaries. There also was a notable concentration of stations with moderate DO levels (2 – 5 mg L-1) in Georgia and South Carolina estuaries. Approximately 58% of the estuarine area had moderate levels of chlorophyll a (5-10 μg L-1) and about 8% of the area had higher levels, in excess of 10 μg L-1, indicative of eutrophication. The elevated chlorophyll a levels appeared to be widespread throughout the estuaries of the region. In contrast, offshore waters throughout the region had relatively low levels of chlorophyll a with 100% of the offshore survey area having values < 5 μg L-1.

Ecological condition of coastal ocean waters of the northwestern Gulf of Mexico: 2011

In August 2011, the NOAA National Ocean Service (NOS) conducted an assessment of the status of ecological condition of soft-bottom habitat and overlying waters of the continental shelf in the northwestern Gulf of Mexico (GOM). The original sampling design included 50 randomly selected sites from the Mississippi River delta to the U.S./Mexican border, representing a total area of 111,162 square kilometers; however, vessel failures and inclement weather precluded sampling at 16 sites in the western-most part of the study region. Sampling was completed at the remaining 34 sites in offshore waters between the Mississippi River delta and Freeport, Texas, representing an estimated 75,591 square kilometers. Field sampling followed standard methods and indicators applied in prior NOAA coastal studies and EPA’s Environmental Monitoring and Assessment Program (EMAP) and National Coastal Assessment (NCA). A key feature adopted from these studies was the incorporation of a random probabilistic sampling design. Such a design provides a basis for making unbiased statistical estimates of the spatial extent of ecological condition relative to various measured indicators and corresponding thresholds of concern. Indicators included multiple measures of water quality, sediment quality, and biological condition (benthic fauna, fish tissue contaminant levels). Water depths ranged from 13 – 83 m throughout the study area. About 9 % of the area had sediments composed of sands (< 20 % silt+clay), 47 % of the area was composed of intermediate muddy sands (20 – 80 % silt+clay), and 44 % of the sampled area consisted of mud (> 80 % silt+clay). About 50 % of the area (represented by 17 sites) had sediment total organic carbon (TOC) concentrations < 5 mg/g and all of the sites sampled had levels of TOC < 20 mg/g, well below the range associated with potentially harmful effects to benthic fauna (> 50 mg/g). Surface salinities ranged from 23.4 – 36.5 psu, with salinity generally increasing with distance west of the Mississippi River delta. Bottom salinities varied between 31.1 and 36.5 psu, with lowest values occurring at shallow, inner-shelf stations. Surface-water temperatures varied between 29.8 and 31.5 ºC, while near-bottom waters ranged in temperature from 19.4 – 31 ºC. An index of density stratification (Δσt) indicated that portions of coastal shelf waters in the northwestern GOM at the time of this sampling were strongly stratified. Values of Δσt at 19 of the 34 sites sampled in this study (56 % of the study area) ranged from 2.2 to 12.4, which is within the range considered to be indicative of strong vertical stratification (Δσt > 2). Stratification was strongest close to the Mississippi River delta, and decreased with distance west of the delta.

Ecological condition of coastal ocean waters of the U.S. continental shelf off South Florida: 2007

A study was initiated with field work in May 2007 to assess the status of ecological condition and stressor impacts throughout the U.S. continental shelf off South Florida, focusing on soft-bottom habitats, and to provide this information as a baseline for evaluating future changes due to natural or human-induced disturbances. The boundaries of the study region extended from Anclote Key on the western coast of Florida to West Palm Beach on the eastern coast of Florida, inclusive of the Florida Keys National Marine Sanctuary (FKNMS), and from navigable depths along the shoreline seaward to the shelf break (~100m). The study incorporated standard methods and indicators applied in previous national coastal monitoring programs — U.S. Environmental Protection Agency’s (EPA) Environmental Monitoring and Assessment Program (EMAP) and National Coastal Assessment (NCA) — including multiple measures of water quality, sediment quality, and biological condition. Synoptic sampling of the various indicators provided an integrative weight-of-evidence approach to assessing condition at each station and a basis for examining potential associations between presence of stressors and biological responses. A probabilistic sampling design, which included 50 stations distributed randomly throughout the region, was used to provide a basis for estimating the spatial extent of condition relative to the various measured indicators and corresponding assessment endpoints (where available). The study was conducted through a large cooperative effort by National Oceanic and Atmospheric Administration (NOAA)/National Centers for Coastal Ocean Science (NCCOS), EPA, U.S. Geological Survey (USGS), NOAA/Oceanic and Atmospheric Research (OAR)/Atlantic Oceanographic and Meteorological Laboratory in Miami, FKNMS, and the Florida Fish and Wildlife Conservation Commission (FWC). The majority of the South Florida shelf had high levels of dissolved oxygen (DO) in near-bottom water (> 5 mg L-1) indicative of “good” water quality.. DO levels in bottom waters exceeded this upper threshold at 98.8% throughout the coastal-ocean survey area. Only 1.2% of the region had moderate DO levels (2-5 mg/L) and no part of the survey area had DO <2.0 mg/L. In addition, offshore waters throughout the region had relatively low levels of total suspended solids (TSS), nutrients, and chlorophyll a indicative of oligotrophic conditions. Results suggested good sediment quality as well. Sediments throughout the region, which ranged from sands to intermediate muddy sands, had low levels of total organic carbon (TOC) below bioeffect guidelines for benthic organisms. Chemical contaminants in sediments were also mostly at low, background levels. For example, none of the stations had chemicals in excess of corresponding Effects-Range Median (ERM) probable bioeffect values or more than one chemical in excess of lower-threshold Effects-Range Low (ERL) values. Cadmium was the only chemical that occurred at moderate concentrations between corresponding ERL and ERM values. Sixty fish samples from 28 stations were collected and analyzed for chemical contaminants. Eleven of these samples (39% of sites) had moderate levels of contaminants, between lower and upper non-cancer human-health thresholds, and ten (36% of sites) had high levels of contaminants above the upper threshold.

Saline-saturated DMSO-EDTA as a storage medium for microbial DNA analysis from coral mucus swab samples

The mucus surface layer of corals plays a number of integral roles in their overall health and fitness. This mucopolysaccharide coating serves as vehicle to capture food, a protective barrier against physical invasions and trauma, and serves as a medium to host a community of microorganisms distinct from the surrounding seawater. In healthy corals the associated microbial communities are known to provide antibiotics that contribute to the coral’s innate immunity and function metabolic activities such as biogeochemical cycling. Culture-dependent (Ducklow and Mitchell, 1979; Ritchie, 2006) and culture-independent methods (Rohwer, et al., 2001; Rohwer et al., 2002; Sekar et al., 2006; Hansson et al., 2009; Kellogg et al., 2009) have shown that coral mucus-associated microbial communities can change with changes in the environment and health condition of the coral. These changes may suggest that changes in the microbial associates not only reflect health status but also may assist corals in acclimating to changing environmental conditions. With the increasing availability of molecular biology tools, culture-independent methods are being used more frequently for evaluating the health of the animal host. Although culture-independent methods are able to provide more in-depth insights into the constituents of the coral surface mucus layer’s microbial community, their reliability and reproducibility rely on the initial sample collection maintaining sample integrity. In general, a sample of mucus is collected from a coral colony, either by sterile syringe or swab method (Woodley, et al., 2008), and immediately placed in a cryovial. In the case of a syringe sample, the mucus is decanted into the cryovial and the sealed tube is immediately flash-frozen in a liquid nitrogen vapor shipper (a.k.a., dry shipper). Swabs with mucus are placed in a cryovial, and the end of the swab is broken off before sealing and placing the vial in the dry shipper. The samples are then sent to a laboratory for analysis. After the initial collection and preservation of the sample, the duration of the sample voyage to a recipient laboratory is often another critical part of the sampling process, as unanticipated delays may exceed the length of time a dry shipper can remain cold, or mishandling of the shipper can cause it to exhaust prematurely. In remote areas, service by international shipping companies may be non-existent, which requires the use of an alternative preservation medium. Other methods for preserving environmental samples for microbial DNA analysis include drying on various matrices (DNA cards, swabs), or placing samples in liquid preservatives (e.g., chloroform/phenol/isoamyl alcohol, TRIzol reagent, ethanol). These methodologies eliminate the need for cold storage, however, they add expense and permitting requirements for hazardous liquid components, and the retrieval of intact microbial DNA often can be inconsistent (Dawson, et al., 1998; Rissanen et al., 2010). A method to preserve coral mucus samples without cold storage or use of hazardous solvents, while maintaining microbial DNA integrity, would be an invaluable tool for coral biologists, especially those in remote areas. Saline-saturated dimethylsulfoxide-ethylenediaminetetraacetic acid (20% DMSO-0.25M EDTA, pH 8.0), or SSDE, is a solution that has been reported to be a means of storing tissue of marine invertebrates at ambient temperatures without significant loss of nucleic acid integrity (Dawson et al., 1998, Concepcion et al., 2007). While this methodology would be a facile and inexpensive way to transport coral tissue samples, it is unclear whether the coral microbiota DNA would be adversely affected by this storage medium either by degradation of the DNA, or a bias in the DNA recovered during the extraction process created by variations in extraction efficiencies among the various community members. Tests to determine the efficacy of SSDE as an ambient temperature storage medium for coral mucus samples are presented here.