Marine biology of the Sierra Leone River Estuary. 1. The physical environment

The Sierra Leone River Estuary is a relatively young drowned river valley, it is shallow except for a deep channel which passes close to the Freetown shoreline. The upper reaches merge into a network of creeks and channels fringed by large areas of mangrove swamps. It is a tidal estuary of the semi-mixed type with the saline oceanic water entering it on a diurnal cycle. The climate of Sierra Leone is marked by a very distinct change between a very wet rainy season and a dry season. The tidal range of the Estuary (spring 3.03m; neap 2.28m) does not impede normal use of the harbour. The tidal variations can be felt as far as 42 miles inland along the water courses of the Sierra Leone River and its tributaries. The volume of fresh water entering the Estuary is large during the rainy season and greatly reduced during the dry season. Consequently there is a marked fall in salinity during the rainy season and higher salinities due to the marine influence prevailing during the dry season. The nature of the shores and bottom, the hydrography and chemistry of the estuarine system have been outlined in relation to the prevailing climatic conditions.

Hypoxic and low pH water in the nearshore marine environments of Monterey Bay, California: characterizing a decade of oxygen and pH, and drivers of variability.

A decade-long time series recorded in southern Monterey Bay, California demonstrates that the shallow, near-shore environment (17 m depth) is regularly inundated with pulses of cold, hypoxic and low pH water. During these episodes, oxygen can drop to biologically threatening levels, and pH levels were lower than expected. Weekly water chemistry monitoring revealed that the saturation state of aragonite (the more soluble form of calcium carbonate) was often below saturation and had a moderate positive relationship with pH, however, analytical and human error could be high. Pulses of hypoxia and low pH water with the greatest intensity arise at the onset of the spring upwelling season, and fluctuations are strongly semidurnal (tidal) and diurnal. Arrival of cold, hypoxic water on the inner shelf typically occurs 3 days after the arrival of a strong upwelling event and appears to be driven by upwelling modulated by internal tidal fluctuations. I found no relationship between the timing of low-oxygen events and the diel solar cycle nor with terrestrial nutrient input. These observations are consistent with advection of hypoxic water from the deep, offshore environment where water masses experience a general decline of temperature, oxygen and pH with depth, and inconsistent with biochemical forcing. Comparisons with concurrent temperature and oxygen time series taken ~20 km away at the head of the Monterey Canyon show similar patterns but even more intense hypoxic events due to stronger semidiurnal forcing there. Analysis of the durations of exposure to low oxygen levels establishes a framework for assessing the ecological relevance of these events. Increasing oceanic hypoxia and acidification of both surface and deep waters may increase the number, intensity, duration and spatial extent of future intrusions along the Pacific coast. Evaluation of the resiliency of nearshore ecosystems such as kelp forests, rocky reefs and sandy habitats, will require consideration of these events.

Evaluation of marine phytoplankton toxicity by application of marine invertebrate bioassays

The dinoflagellate Alexandrium minutum and the haptophyte Prymnesium parvum are well known for their toxin production and negative effects in marine coastal environments. A. minutum produces toxins which cause paralytic shellfish poisoning in humans and can affect copepods, shellfish and other marine organisms. Toxins of P. parvum are associated with massive fish mortalities resulting in negative impacts on the marine ecosystem and large economic losses in commercial aquaculture. The aim of this work is to improve our knowledge about the reliability of the use of marine invertebrate bioassays to detect microalgae toxicity, by performing: (i) a 24- to 48-h test with the brine shrimp Artemia franciscana; (ii) a 48-hour embryo-larval toxicity test with the sea urchin Paracentrotus lividus; and (iii) a 72-h test with the amphipod Corophium multisetosum. The results indicate that A. franciscana and P. lividus larvae are sensitive to the toxicity of A. minutum and P. parvum. LC50 comparison analysis between the tested organisms reveals that A. franciscana is the most sensitive organism for A. minutum. These findings suggest that the use of different organizational biological level bioassays appears to be a suitable tool for A. minutum and P. parvum toxicity assessment.

Integrated assessment of environmental pollution using diverse sentinel organisms within Basque marine environments

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Environmental quality standards to protect identified uses of controlled waters: salmonid fisheries, cyprinid fisheries, migratory fisheries, commercial harvesting of marine fish for public consumption, commercial harvesting of shellfish for for public consumption

This report considers the development of environmental quality standards (EQSs) for the salmonid fishery, cyprinid fishery, migratory fishery, commercial harvesting of marine fish for public consumption and commercial harvesting of shellfish for public consumption uses of controlled surface waters. Previous reports have been used to identify those parameters necessary for the maintenance of these five uses. Each water use is considered in a separate section within which identified parameters are discussed and standards proposed, a summary of the proposed standards is presented at the beginning of the relevant section. For salmonid, cyprinid and migratory fisheries, EQSs for substances in water have been proposed for the protection of these fisheries. For the commercial harvesting of marine fish and shellfish for public consumption uses 'Warning Levels' of substances in waters have been proposed. These 'Warning Levels' have been proposed by considering data on bioaccumulation and food standards and aim to prevent acceptable intake values and concentrations in fish/shellfish flesh exceeding statutory or recommended levels. For the commercial harvesting of marine fish for public consumption it has been concluded that the current EQSs for most List II substances for the protection of salt water life should be adequately stringent to protect this use, however for the commercial harvesting of shellfish for public consumption, these List II EQSs do not appear adequate to protect this use and more stringent 'Warning Levels' have been proposed. For all five uses considered in this report there has been found to be limited information on a number of the parameters considered and in general for indigenous species, this has been found to be especially so when considering migratory fisheries and the commercial harvesting of marine fish and shellfish.

Smoked marine fish from Western Region, Ghana: a value chain assessment

The value chain analysis of ths report focused on smoked marine fish- overwhelmingly the most important fish product originating in Western Region, Ghana. Smoked fish from Western Region is mainly destined for the domestic market where demand is very strong. Small quantities of smoked fish are destined for markets in Togo, Benin and Nigeria. The underlying objective of the fisheries value chain analysis is to identify opportunities for growth in the fisheries value chain, with an emphasis on those opportunities that have the potential to generate significant additional livelihoods, particularly at the level of the fishing communities and for low-income groups. The results from the value chain analysis will be used to identify pilot interventions to promote those livelihood outcomes. The main focus for the study is smoked fish (major species/product forms) destined for domestic markets. However, work will also be undertaken on the fresh fish trade and frozen fish to find out more about the significance of these value chains.

Estimating the abundance of clustered and cryptic marine macro-invertebrates in the Galápagos with particular reference to sea cucumbers

Estimating the abundance of marine macro-invertebrates is complicated by a variety of factors: 1) human factors, such as diver efficiency and diver error; and 2) biological factors, such as aggregation of organisms, crypsis, and nocturnal emergence behavior. Diver efficiency varied according to the detectability of an organism causing under-estimation of density by up to 50% in some species. All common species were aggregated at scales from 10-50 m. Transects need to be long enough to transcend the scale of patchiness to improve accuracy. Some species of sea urchins and sea cucumbers (pepinos) which are cryptic by day emerged at night so that daytime censuses underestimated their abundance by up to 10 times. In the sea cucumber fishery, estimates of abundance need to be made at the scale of the population, i.e. at hundreds of km. A strategy for this is proposed.

Creating a collection development model for a marine science library

The purpose of this article is to update and build on the approximate 10,000 item collection of the Harbor Branch Oceanographic Institute Library. This article will present a history of Harbor Branch and its library, and a literature review, outlining the collection development methods of other marine science libraries and academic libraries. The article will relate brief histories of three marine science libraries. A comparative table is constructed to compare Harbor Branch Library with three marine science libraries. The methodology, or how the table was created, is explained. The comparative table will be shown and analyzed, and the results of the table discussed. Finally, some recommendations for improvement of the Harbor Branch Library will be presented.

Revealing the appetite of the marine aquarium fish trade: the volume and biodiversity of fish imported into the United States

The aquarium trade and other wildlife consumers are at a crossroads forced by threats from global climate change and other anthropogenic stressors that have weakened coastal ecosystems. While the wildlife trade may put additional stress on coral reefs, it brings income into impoverished parts of the world and may stimulate interest in marine conservation. To better understand the influence of the trade, we must first be able to quantify coral reef fauna moving through it. Herein, we discuss the lack of a data system for monitoring the wildlife aquarium trade and analyze problems that arise when trying to monitor the trade using a system not specifically designed for this purpose. To do this, we examined an entire year of import records of marine tropical fish entering the United States in detail, and discuss the relationship between trade volume, biodiversity and introduction of non-native marine fishes. Our analyses showed that biodiversity levels are higher than previous estimates. Additionally, more than half of government importation forms have numerical or other reporting discrepancies resulting in the overestimation of trade volumes by 27%. While some commonly imported species have been introduced into the coastal waters of the USA (as expected), we also found that some uncommon species in the trade have also been introduced. This is the first study of aquarium trade imports to compare commercial invoices to government forms and provides a means to, routinely and in real time, examine the biodiversity of the trade in coral reef wildlife species.

Prey preference of lingcod (Ophiodon elongatus), a top marine predator: implications for ecosystem-based fisheries management

Many highly exploited ecosystems are managed on the basis of single-species demographic information. This management approach can exacerbate tensions among stakeholders with competing interests who in turn rely on data with notoriously high variance. In this case study, an application of diet and dive survey data was used to describe the prey preference of lingcod (Ophiodon elongatus) in a predictive framework on nearshore reefs off Oregon. The lingcod is a large, fast-growing generalist predator of invertebrates and fishes. In response to concerns that lingcod may significantly reduce diminished populations of rockfishes (Sebastes spp.), the diets of 375 lingcod on nearshore reefs along the Oregon Coast were compared with estimates of relative prey availability from dive surveys. In contrast to the transient pelagic fishes that comprised 46% of lingcod diet by number, rockfishes comprised at most 4.7% of prey items. Rockfishes were the most abundant potential prey observed in dive surveys, yet they were the least preferred. Ecosystem-based fisheries management (EBFM) requires information about primary trophic relationships, as well as relative abundance and distribution data for multiple species. This study shows that, at a minimum, predation relative to prey availability must be considered before predator effects can be understood in a management context.

Effects of starvation on energy density of juvenile chum salmon (Oncorhynchus keta) captured in marine waters of Southeastern Alaska

We conducted laboratory starvation experiments on juvenile chum salmon (Oncorhynchus keta) captured in the neritic marine waters of northern Southeast Alaska in June and July 2003. Temporal changes in fish energy density (whole body energy content [WBEC], cal/g dry weight), percent moisture content, wet weight (g), length (mm), and size-related condition residuals were measured in the laboratory and were then compared to long-term field data. Laboratory water temperatures and salinities averaged 9°C and 32 psu in both months. Trends in response variables were similar for both experimental groups, although sampling intervals were limited in July because fewer fish were available (n= 54) than in June (n=101). Overall, for June (45-d experimental period, 9 intervals), WBEC, wet weight, and condition residuals decreased and percent moisture content increased, whereas fork length did not change. For July (20-d experimental period, 5 intervals), WBEC and condition residuals decreased, percent moisture content and fork length increased, and wet weight did not change. WBEC, percent moisture content, and condition residuals fell outside the norm of longterm data ranges within 10–15 days of starvation, and may be more useful than fork length and wet weight for detecting fish condition responses to suboptimal environments.