In this course, taught at the Pymatuning Laboratory of Ecology in northwest Pennsylvania, students will explore the population, community, and ecosystem ecology of fishes. We will conduct field investigations in streams, lakes, and marshes. Students will attend background lectures, conduct experiments and field surveys, participate in data collection and analysis, and gain experience in the interpretation and presentation of results. We will learn how to integrate math, physics, chemistry, and biology in our study of fishes. In addition, we seek to expose students to current research in fish ecology. Students will participate in the design of experiments, data analysis, and hone their presentation skills. Most importantly, they will leave the course with a greater knowledge of and appreciation for Pennsylvania’s rich diversity of fishes.

Ecology of fishes

https://munin.uit.no/bitstream/handle/10037/8602/article.pdf;sequence=5

In the dark: A review of ecosystem processes during the Arctic polar night

The fate of ice-bottom algae, before and after release from the first-year sea ice into the water column, was assessed during the period of ice-algal growth and decline in Resolute Passage (Canadian Arctic). During spring 1992 (from April to June), algae in the bottom ice layer and those suspended and sinking in the upper water column (top 15 m) were sampled approximately every 4 days. Ice-bottom chlorophyll a reached a maximum concentration of 160 mg m−2 in mid-May, after which it decreased to lower values. In the water column, chlorophyll a concentrations were low until the period of ice-algal decline (∼0.1 mg m−3), with most biomass in the 65% of total export) and that ice-algae were ingested by under-ice grazers after release from the ice. These results stress the importance of ice algae for pelagic consumers during the early stages of ice melt and show that the transfer of ice algae to higher trophic levels extends beyond the period of maximum algal production in the ice bottom.

Carbon budget of sea‐ice algae in spring: Evidence of a significant transfer to zooplankton grazers

We review intrinsic traits of the early life stages of marine fishes to gain a better understanding of how climate-driven changes in abiotic (temperature) and biotic (match–mismatch dynamics with prey) factors may differ among taxonomic groups and/or habitats (from low to high latitudes). Intrinsic traits related to the thermal sensitivity of development of endogenously feeding life stages included the time required for eggs to hatch (58 species, 26 families), the size of larvae at hatch (31 spp., 15 families) and the time required for young larvae to deplete energy reserves (48 spp., 22 families). These intrinsic factors will influence spatiotemporal match–mismatch dynamics at first feeding, a critical period for growth and survival. In exogenously feeding larvae, key intrinsic traits reviewed included differences in early morphology and developmental trajectories (64 spp., 20 families) and the foraging ability of marine fish larvae. Routine and critical swimming speeds were 5–10 times higher in the larvae of species from low (tropical) versus higher (temperate/polar) latitudes. Based solely on routine metabolic losses (26 spp., 15 families), sevenfold increases in larval foraging requirements were estimated between 5 and 25 °C to offset starvation. Finally, a thorough review of larval diets (57 spp., 20 families) found clear differences (particularly at first feeding) by taxon and habitat. Our review and synthesis highlights gaps in knowledge and recommends future research directions to stengthen how larval development, feeding, and growth are depicted within individual-based models, which are useful tools for examining climate-driven processes affecting marine fishes and how intrinsic properties and extrinsic factors interact to influence survival. We argue that thorough, taxonomic and habitat-based comparisons of intrinsic properties of fish larvae are required to adequately project potential impacts of climate change on the distribution and productivity of marine fish species.

Chapter 3 – Intrinsic and Extrinsic Factors Driving Match–Mismatch Dynamics During the Early Life History of Marine Fishes

In the warming Arctic, aquatic habitats are in flux and salmon are exploring their options. Adult Pacific salmon, including sockeye (Oncorhynchus nerka), coho (O. kisutch), Chinook (O. tshawytscha), pink (O. gorbuscha) and chum (O. keta) have been captured throughout the Arctic. Pink and chum salmon are the most common species found in the Arctic today. These species are less dependent on freshwater habitats as juveniles and grow quickly in marine hab- itats. Putative spawning populations are rare in the North American Arctic and limited to pink salmon in drainages north of Point Hope, Alaska, chum salmon spawning rivers draining to the northwestern Beaufort Sea, and small populations of chum and pink salmon in Canada's Mackenzie River. Pacific salmon have colonized several large river basins draining to the Kara, Laptev and East Siberian seas in the Russian Arctic. These populations probably developed from hatchery supplementation efforts in the 1960's. Hundreds of populations of Arctic Atlantic salmon (Salmo salar) are found in Russia, Norway and Finland. Atlantic salmon have extended their range eastward as far as the Kara Sea in central Russian. A small native population of Atlantic salmon is found in Canada's Ungava Bay. The northern tip of Quebec seems to be an Atlantic salmon migration barrier for other North American stocks. Compatibility between life history requirements and ecological conditions are prerequisite for salmon colonizing Arctic habitats. Broad-scale predictive models of climate change in the Arctic give little information about feedback pro- cesses contributing to local conditions, especially in freshwater systems. This paper reviews the recent history of salmon in the Arctic and explores various patterns of climate change that may influence range expansions and future sustainability of salmon in Arc- tic habitats. A summary of the research needs that will allow informed expectation of further Arctic coloniza- tion by salmon is given.

Adaptive strategies and life history characteristics in a warming climate: salmon in the Arctic?

From 1988 to 1990, fish larvae were sampled before, during, and after ice breakup within and outside the plume of the Great Whale River off Kuujjuarapik, southeastern Hudson Bay, Canada. Arctic cod (Boreogadus saida) and sand lance (Ammodytes spp.) were the most abundant larvae. Half of the larval fish taxa emerged before the ice broke up in the Bay. The highest densities of Arctic cod, sand lance, slender eelblenny, and gelatinous snailfish larvae were in salinities exceeding 25 practical salinity units (p.s.u.). Arctic shanny, sculpins, and capelin larvae were more abundant at salinities between 1 and 25 p.s.u.. Burbot and coregonid larvae were clearly associated with fresh or brackish waters even when caught in the Bay. The timing and extent of the Great Whale River freshet influenced the distribution of marine fish larvae in southeastern Hudson Bay and determined the moment when the larvae of anadromous and freshwater species entered the Bay.

/pdf/production-and-dispersion-of-freshwater-anadromous-and-3w2ks51olm.pdf

J.A. Gagné

Papers

Production and dispersion of freshwater, anadromous, and marine fish larvae in and around a river plume in subarctic Hudson Bay, Canada