The objective of the present study is then limited to investigate the parasitic fauna of marine fishes from Ensenada, Baja California, and to compile in a single manuscript all data (Host-Parasite list, Parasite-Host list, and distribution of parasites) on digenea previously reported from the Mexican Pacific and the Gulf of California.

Examination of 154 fishes representing 45 species from the Jamaican north shore yielded 43 species of digenea in 12 families.

Four new species of Hurleytrematoides Y amaguti, 1954 are described: H. fl}iensis from Heniochus acuminatus pnd Chaetodon citrinellus, H. prevoti from Chaetodon melannotus; H bartolii from Heniochus acuminatus and H monoceros, and H. zebrasomae from Zebrasoma scopas. The hurleytrematine genera Hurleytrema, Hurleytrematoides, Pseudohurleytrema and Parahurleytrema are briefly discussed and their validity accepted based chiefly on the structure of the male and female terminal structures. Hurleytrema pyriforme Overstreet, 1969 and H. catarinensis Amato, 1982 are transferred to Pseudohur/eytrema as new combinations. The generic diagnosis of Hurleytrematoides is emended to include cirrus with large and extensive spines or small ones with limited distribution, and a spiny or aspinose unipartite terminal organ. A key to the hurleytrematine genera with single testis and their species is given. A parasite-host list of all monorchiid species reported to date is included.

six species of gyliauchenids are reported in this study, five in the genus Gyliauchen and one in Apharyngogyliauchen. G. pomacentri n.sp. is described from a single specimen recovered from one of one Pomacentrus philippinus, G. parapapillatus n.sp. is described from 42 specimens in one of one Siganus virgatus. Gyliauchen zancli n.sp. is described from a single specimen in one of one Zanclus cornutus. Gyliauchen nahaensis Ozaki, 1937 is redescribed from 189 specimens in one of two siganus punctatus and establishes a new locality record, and in one of one zanclas cornutus, a new host record. Gyliauchen sp. is described from two specimens of two of four Siganus spinus.

Local and regional patterns of distribution and abundance are documented in marine rocky-reef fishes. Chapter one describes limits of distribution and patterns of density variation of two fishes in a northern Gulf of California intertidal shore. The density of Sonora gobies (Gobiosoma chiquita) increases with tidal height over its intertidal range (-1.2 to 0.9 m), whereas the density of patchscale gobies (Gobiosoma sp.) decreases from the subtidal zone to 0.6 m above mean low water level. Both species exhibit higher densities during the warmer season when intertidal temperature gradients are weaker than during the colder season. Sonora gobies show a broader range of temperature tolerance than patchscale gobies but there is no evidence of shifts in distribution between seasons suggesting that the distributions of these species are not determined by temperature. Interspecific interactions may contribute to the patterns of intertidal distribution and abundance in these species despite the rigorous physical environment of the area. Chapter two documents a positive correlation between average local abundance and extent of geographic distribution in rocky-shore fishes from the Gulf of California. This correlation is not an artifact of sampling an arbitrarily defined region and is unlikely to be an artifact of sampling bias. The occurrence of this relationship in a variety of organisms suggests that the processes responsible for this pattern are likely to be similar in both terrestrial and marine environments despite fundamental differences between the two. Chapter three demonstrates that egg type and adult body size explain a considerable portion of the variation in extent of geographic range in marine reef fishes. Species with pelagic eggs have larger geographic ranges, longer larval lives, and larger body sizes than species with non-pelagic eggs. Small species with non-pelagic eggs show smaller geographic ranges than any other combination of body size and egg type. These biogeographic patterns predict a greater degree of genetic isolation among populations, and a greater species turnover over evolutionary time in clades of small species with non-pelagic eggs than in clades of species with other combinations of body size and egg type.

Convergence in body form and discrete morphological characters among fishes of similar habits is widespread in both freshwater and marine habitats. The identification of adaptive types of fishes alludes to predictive relationships between morphology and lifestyle. Now, a challenge confronting

Goatfishes inhabit inshore reefs and corals and are commercially important across their distribution in the Western Indian Ocean (WIO). The biogeography of these species in the WIO has not been explored with regards to their levels of diversity and relationships among regions. The genetic connectivity and differentiation of three goatfishes of the genus Parupeneus (P. barberinus, P. macronemus and P. rubescens) was studied using two mitochondrial genes (ND2 and 16S rRNA) and one nuclear gene (RAG1) using specimens from East and southern Africa, islands around the Mascarene plateau, Oman, Maldives and the Red Sea. Haplotype diversities, networks and AMOVA were used to measure genetic variance among localities and defined regional groups. There were high haplotype (HD > 0.9) and low nucleotide diversities (< 0.006) among all species for all gene regions, suggesting high levels of genetic differentiation among different areas, except for the mtDNA 16S data for P. macronemus and P. rubescens. For all three species, the FST population pairwise values revealed significant differentiation in all datasets for most population pairwise comparisons with the Maldives and genetic connectivity with haplotypes being shared among other localities. The 16S and RAG1, AMOVA for P. barberinus revealed a significant (P < 0.05) strong genetic structure among groups, for example P = 0.00 was estimated in the 16S data for four groups (the Maldives, WIO islands, Kenya and eastern mainland). This study found evidence for regional differentiation within the WIO for these three species supporting the presence of genetic breaks among areas. This differentiation could be either due to the historical isolation among areas or due to geographic and oceanic barriers such as the Mascarene Plateau and the Agulhas Current eddies in the Mozambique Channel. The effects of oceanographic features and physical barriers in the species distribution range and the dispersal potential based on the life history features of the species can have an influence on the genetic structuring of a population. It is also important to note that the length of the pelagic larval phase is just one factor affecting dispersal in marine organisms that can also explain the difference in genetic population structure. Unfortunately there is no specific information on the larval dispersal of these three goatfish. Therefore, studies are needed to be conducted on the specific biology and life history strategies of each Parupeneus species. These results suggest the importance of other factors, such as currents, and larval retention that may cause strong differentiation. These factors should also be considered when observing larval dispersal and its effect on population genetic structure. This study support the hypotheses that physical factors, processes (geographic barriers and oceanographic characteristics) and life history parameters need to be studied to understand the genetic differentiation of these Parupeneus reef fishes.

Allozyme frequencies and general protein patterns were surveyed among selected Texas marine fishes and shellfishes to illustrate the application of biochemical genetic techniques to stock and species identification in fisheries management.

Six species of haplosplanchnids are reported in this study. Haplosplanchnus caudatus (Srivastava, 1939) Skrjabin and Guschanskaja, 1955 was found in large numbers in 8 of 9 Mugil cephalus. H. purii Srivastava, 1939 was found in small numbers in 2 of 9 Liza vaigiensis and 1 of 9 Mugil cephalus. Both of these findings represent a new locality record. Schikhobalotrema southi n. sp. is described from a single specimen from Scarus rivulatus. S. scari n. sp. from the same host is also described from a single specimen. Schikhobalotrema sp. is described but not named because of insufficient data. Hymenocotta mulli Manter, 1961 from Mugil cephalus and Liza vaigiensis is also reported, based on one specimen from each host. New synonyms: Haplosplanchnus stunkardi Gupta and Ahmad, 1979 is a synonym of H. caudatus (Srivastava, 1939) Skrjabin and Guschanskaja, 1955. H. otolithi Gupta and Ahmad, 1979 is a synonym of H. purii Srivastava, 1939. Neohaplosplanchnus ablennis Abdul-Salam and Khalil, 1987 is transferred to the genus Schikhobalotrema becoming S. ablennis n. comb. A key to the genus Schikhobalotrema including the new species is included.

The following seven species of hemiurid trematodes, some with new host records, are reported in this study: Dissosaccus laevis, Genolinea laticauda, Lecithaster salmonis, Parahemiurus merus, Sterrhurus exodicus, Sterrhurus monticelli and Tubulovesicula lindbergi. Dissosaocus laeyis and Sterrhurus monticelli are reported for the first time from the West Coast of North America. Genolinea oncorhynohi Adams and Margolis 1958 is placed in synonymy with Genolinea laticauda Manter 1925. Keys for Genolinea and Tubulovesicula species, modified from Manter (1954) are included. Two tables, one summarizing the hemiurids reported from the West Coast of North America, the other a summary of hemiurids from Monterey Bay, California, encountered in this study, are also included.