Pressures on the biota in the aquatic ecosystem of (Chi) Cross River National Park, Okwango Division

A preliminary survey of Cross River National Park (Nigeria), Okwangwo Division was carried out. The combined natural and human pressures being exerted on the aquatic resources were also investigated. Information on the existing fishing communities in and around the park area are given. The fishermen, their fishing methods and fishing grounds were identified. Limiting factors (natural and human) to the fisheries production, are analysed. Positive measures for conservation, protection and management of healthy and natural aquatic environment are suggested

Soft-bottom benthic assemblages and levels of contaminants in sediments and biota at Gray's Reef National Marine Sanctuary and nearby shelf waters off the coast of Georgia (2000 and 2001)

A series of studies was initiated to assess the condition of benthic macroinfauna and chemical contaminant levels in sediments and biota of the Gray’s Reef National Marine Sanctuary (GRNMS) and nearby shelf waters off the coast of Georgia. Four key objectives of the research are (1) to document existing environmental conditions within the sanctuary in order to provide a quantitative benchmark for tracking any future changes due to either natural or human disturbances; (2) to examine broader cross-shelf spatial patterns in benthic fauna and sediment contaminant concentrations and to identify potential controlling factors associated with the observed patterns; (3) to assess any between-year temporal variability in benthic fauna; and (4) to evaluate the importance of benthic fauna as prey for higher trophic levels. Such questions are being addressed to help fulfill long-term science and management goals of the GRNMS. However, it is anticipated that the information will be of additional value in broadening our understanding of the surrounding South Atlantic Bight (SAB) ecosystem and in bringing the knowledge to bear on related resourcemanagement issues of the region. We have begun to address the first three of these objectives with data from samples collected in spring 2000 at stations within GRNMS, and in spring 2001 at stations within the sanctuary and along three cross-shelf transects extending from the mouths of Sapelo, Doboy, and Altamaha Sounds out to sanctuary depths (about 17-20 m). This report provides a description of baseline conditions within the sanctuary, based on results of the spring 2000 survey (Section II), and uses data from both 2000 and 2001 to examine overall spatial and temporal patterns in biological and chemical variables within the sanctuary and surrounding inner-shelf environment (Section III). (PDF contains 65 pages)

2002-03 Florida Keys National Marine Sanctuary science report: An ecosystem report card after five years of marine zoning

Executive Summary: Circulation and Exchange of Florida Bay and South Florida Coastal Waters The coastal ecosystem of South Florida is comprised of distinct marine environments. Circulation of surface waters and exchange processes, which respond to both local and regional forcings, interconnect different coastal environments. In addition, re-circulating current systems within the South Florida coastal ecosystem such as the Tortugas Gyre contribute to retention of locally spawned larvae. Variability in salinity, chlorophyll, and light transmittance occurs on a wide range of temporal and spatial scales, in response to both natural forcing, such as seasonal precipitation and evaporation and interannual “El Niño” climate signals, and anthropogenic forcing, such as water management practices in south Florida. The full time series of surface property maps are posted at www.aoml.noaa.gov/sfp. Regional surface circulation patterns, shown by satellite-tracked surface drifters, respond to large-scale forcing such as wind variability and sea level slopes. Recent patterns include slow flow from near the mouth of the Shark River to the Lower Keys, rapid flow from the Tortugas to the shelf of the Carolinas, and flow from the Tortugas around the Tortugas Gyre and out of the Florida Straits. The Southwest Florida Shelf and the Atlantic side of the Florida Keys coastal zone are directly connected by passages between the islands of the Middle and Lower Keys. Movement of water between these regions depends on a combination of local wind-forced currents and gravitydriven transports through the passages, produced by cross-Key sea level differences on time scales of several days to weeks, which arise because of differences in physical characteristics (shape, orientation, and depth) of the shelf on either side of the Keys. A southeastward mean flow transports water from western Florida Bay, which undergoes large variations in water quality, to the reef tract. Adequate sampling of oceanographic events requires both the capability of near real-time recognition of these events, and the flexibility to rapidly stage targeted field sampling. Capacity to respond to events is increasing, as demonstrated by investigations of the 2002 “blackwater” event and a 2003 entrainment of Mississippi River water to the Tortugas. (PDF contains 364 pages.)

Distribution and sighting frequency of reef fishes in the Florida Keys National Marine Sanctuary

This study analyzed species richness, distribution, and sighting frequency of selected reef fishes to describe species assemblage composition, abundance, and spatial distribution patterns among sites and regions (Upper Keys, Middle Keys, Lower Keys, and Dry Tortugas) within the Florida Keys National Marine Sanctuary (FKNMS) barrier reef ecosystem. Data were obtained from the Reef Environmental Education Foundation (REEF) Fish Survey Project, a volunteer fish-monitoring program. A total of 4,324 visual fish surveys conducted at 112 sites throughout the FKNMS were used in these analyses. The data set contained sighting information on 341 fish species comprising 68 families. Species richness was generally highest in the Upper Keys sites (maximum was 220 species at Molasses Reef) and lowest in the Dry Tortugas sites. Encounter rates differed among regions, with the Dry Tortugas having the highest rate, potentially a result of differences in the evenness in fishes and the lower diversity of habitat types in the Dry Tortugas region. Geographic coverage maps were developed for 29 frequently observed species. Fourteen of these species showed significant regional variation in mean sighting frequency (%SF). Six species had significantly lower mean %SF and eight species had significantly higher mean %SF in the Dry Tortugas compared with other regions. Hierarchical clustering based on species composition (presence-absence) and species % SF revealed interesting patterns of similarities among sites that varied across spatial scales. Results presented here indicate that phenomena affecting reef fish composition in the FKNMS operate at multiple spatial scales, including a biogeographic scale that defines the character of the region as a whole, a reef scale (~50-100 km) that include meso-scale physical oceanographic processes and regional variation in reef structure and associated reef habitats, and a local scale that includes level of protection, cross-shelf location and a suite of physical characteristics of a given reef. It is likely that at both regional and local scales, species habitat requirements strongly influence the patterns revealed in this study, and are particularly limiting for species that are less frequently observed in the Dry Tortugas. The results of this report serve as a benchmark for the current status of the reef fishes in the FKNMS. In addition, these data provide the basis for analyses on reserve effects and the biogeographic coupling of benthic habitats and fish assemblages that are currently underway. (PDF contains 61 pages.)

A review of the crayfish fishery of Nigeria with special reference to the Cross River State

The fishery for crayfish is of considerable importance in the maritime region of the Cross River State, Nigeria, where it forms an important occupation of a host of fishermen. Crayfish landings from this State contributed 11% to the national marine fish landings within the period 1980 to 1984 and also in the same period the volume of crayfish alone formed 26% of the marine fish landings within the State. The species exploited as crayfish include Palaemon hastatus; Hippolysmata hastatoides, and Macrobrachium sp; mixed with the larval, and juveniles of pink shrimp Panaeus dourarum. They are generally small in size ranging from 7 cm (maximum) to 2.5 cm. Crayfish are caught all year round along the Niger Delta, but particularly along the river estuaries and littoral waters of the Cross River State with the highest production occurring in March to May. Crayfish are usually smoked, and occasionally sun-dried, and they form an indispensable food item in the diet of the people of the entire southern States in particular and Nigeria in general. It appears that crayfish landings could be substantially increased without depleting the stock, if a proper exploratory survey is undertaken of the Niger delta, and the Cross River estuaries to chart potentially rich grounds of this resource

A review of bonga fisheries of the Cross River State, Nigeria

The Nigerian pelagic fishery contributes about two-thirds of the total marine fishery resources of the country. The main components of this fishery are the clupeid (Ethmalosa, and Sardinella spp) and the scombroid (jacks, barracuda and tuna) fisheries. In 1979 to 1983, fish production from the national inshore and brackishwater zones was 1,702,685 tonnes. Bonga (Ethmalosa fimbriata) which dominates the pelagic fishery in the Cross River State of Nigeria, contributed about 158,612 tonnes (i.e. 9.3%) of this national marine fish catch. Although bonga is caught along the entire Nigerian coast, a significant fishery exists mostly in the wider estuary of the Cross River State, which borders on the Cameroon Republic. In the Cross River State, and within the period, bonga contributed 24% to the marine fish landings. Bonga is supported by a single species (E. fimbriata). The species forms an important fishery all the year-round in the open sea off these estuaries, whenever the canoes venture to sea, but these open sea fisheries are affected by whether conditions. The best, and most suitable gear for bonga are the gill nets, cast nets, boat seines, and shore seines. Dried and smoked bonga are a common market commodity in the southern parts of the country generally, but particularly in the Cross State where it is a readily available and acceptable food item

Cross-shelf and seasonal variation in larval fish assemblages on the southeast United States continental shelf off the coast of Georgia

Seasonal and cross-shelf patterns were investigated in larval fish assemblages on the continental shelf off the coast of Georgia. The influence of environmental factors on larval distributions also was examined, and larval transport processes on the shelf were considered. Ichthyoplankton and environmental data were collected approximately every other month from spring 2000 to winter 2002. Ten stations were repeatedly sampled along a 110-km cross-shelf transect, including four stations in the vicinity of Gray’s Reef National Marine Sanctuary. Correspondence analysis (CA) on untransformed community data identified two seasonal (warm weather [spring, summer, and fall] and winter) and three cross-shelf larval assemblages (inner-, mid-, and outer-shelf ). Five environmental factors (temperature, salinity, density, depth of the water column, and stratification) were related to larval cross-shelf distribution. Specifically, increased water column stratification was associated with the outer-shelf assemblage in spring, summer, and fall. The inner shelf assemblage was associated with generally lower temperatures and lower salinities in the spring and summer and higher salinities in the winter. The three cross-shelf regions indicated by the three assemblages coincided with the location of three primary water masses on the shelf. However, taxa occurring together within an assemblage were transported to different parts of the shelf; thus, transport across the continental shelf off the coast of Georgia cannot be explained solely by twodimensional physical factors.

National Centers for Coastal Ocean Science (NCCOS) research highlights in the Chesapeake Bay

The Chesapeake Bay is the largest estuary in the United States. It is a unique and valuable national treasure because of its ecological, recreational, economic and cultural benefits. The problems facing the Bay are well known and extensively documented, and are largely related to human uses of the watershed and resources within the Bay. Over the past several decades as the origins of the Chesapeake’s problems became clear, citizens groups and Federal, State, and local governments have entered into agreements and worked together to restore the Bay’s productivity and ecological health. In May 2010, President Barack Obama signed Executive Order number 13508 that tasked a team of Federal agencies to develop a way forward in the protection and restoration of the Chesapeake watershed. Success of both State and Federal efforts will depend on having relevant, sound information regarding the ecology and function of the system as the basis of management and decision making. In response to the executive order, the National Oceanic and Atmospheric Administration’s National Centers for Coastal Ocean Science (NCCOS) has compiled an overview of its research in Chesapeake Bay watershed. NCCOS has a long history of Chesapeake Bay research, investigating the causes and consequences of changes throughout the watershed’s ecosystems. This document presents a cross section of research results that have advanced the understanding of the structure and function of the Chesapeake and enabled the accurate and timely prediction of events with the potential to impact both human communities and ecosystems. There are three main focus areas: changes in land use patterns in the watershed and the related impacts on contaminant and pathogen distribution and concentrations; nutrient inputs and algal bloom events; and habitat use and life history patterns of species in the watershed. Land use changes in the Chesapeake Bay watershed have dramatically changed how the system functions. A comparison of several subsystems within the Bay drainages has shown that water quality is directly related to land use and how the land use affects ecosystem health of the rivers and streams that enter the Chesapeake Bay. Across the Chesapeake as a whole, the rivers that drain developed areas, such as the Potomac and James rivers, tend to have much more highly contaminated sediments than does the mainstem of the Bay itself. In addition to what might be considered traditional contaminants, such as hydrocarbons, new contaminants are appearing in measurable amounts. At fourteen sites studied in the Bay, thirteen different pharmaceuticals were detected. The impact of pharmaceuticals on organisms and the people who eat them is still unknown. The effects of water borne infections on people and marine life are known, however, and the exposure to certain bacteria is a significant health risk. A model is now available that predicts the likelihood of occurrence of a strain of bacteria known as Vibrio vulnificus throughout Bay waters.